Sexually mature Long-Evans male rats show a strict preference for odors of receptive females over those of males or ovariectomized females. Our previous study demonstrated that castration induces transient reversal of sex orientation (preferring males to females), which is diminished during the course of observation over a 3-week period (Xiao et al., 2003). In this study, we investigated the effects of testosterone (T), or dihydrotestosterone (DHT) on sex-orientation in castrated males using cholesterol (C) as control. Another group in which intact males were treated with an aromatase inhibitor, formestane (4-hydroxyandrostenedione, 4-OHA). Subcutaneous implantation of Silastic capsule containing T, DHT and 4-OHA, but not C, produced obvious male-typical orientation along with male sexual behavior. Males with T also preferred castrated males to sexually active males, whereas males with DHT or 4-OHA had no preference for castrated males. After the removal of the capsule or castration of 4-OHA males, T males showed transient reversal of sex orientation for 2-3 weeks, even though they showed male sexual behavior when placed with receptive females. In contrast, DHT and 4-OHA males had no preference at all after the removal of the capsule or castration. The results indicate that estrogen generated by aromatization of testosterone induces female-like sex orientation in the castrated males. [Jpn J Physiol 55 Suppl:S213 (2005)]

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ERβ mRNA and protein were visualized in the adult rat forebrain by non-isotopic, digoxigenin-labeled in situ hybridization histochemistry and immunohistochemistry. All ERβ-mRNA positive cells expressed ERβ protein. In the ventromedial hypothalamic nucleus (VMN) of gonadectomized males and females, ERβ positive cells scattered along the rostrocaudal axis with an increasing number toward the caudal, ventrolateral portion. In gonadectomized animals, females had contained a significantly larger number of ERβ-positive cells than males. Estrogen supplement caused significant reductions in the number of ERβ positive cells in both sexes. Infusion of a retrograde tracer, Fluoro-Gold in the midbrain central gray (CG) at the mid-collicular level labeled about 30% of ERβ positive cells in the caudal portion of the VMN. Sex-difference in the number of ERβ-positive cells with CG projection suggests sex-specific modulation of autonomic sensory or behavioral function of estrogen through ERβ. [Jpn J Physiol 55 Suppl:S213 (2005)]

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In primates including humans, it is believed that there is no sex difference in the function of the hypothalamus associated with the induction of LH surge, because estrogen can induce a surge-like LH scretion in castrated males. We examined whether P could induce a surge-like LH secretion in estrogen-primed TG and TS women. Control women (N=4, 27-39 yr), TG women (N=3, 29-32 yr), and TS women (N=3, 23-29 yr) provided written informed consent. TG and TS women were diagnosed as gender identity disorder by medical specialists, and had not received any hormonal treatment. Except one in TS women, others had a regular menstrual cycle, based on the basal body temperature and the menstruation. Subjects were administered orally with 50 μg of ethinylestradiol (E) twice per day for 5 days from day 3. On day 7, subjects were injected s.c. with 12.5 mg of P. Blood samples were collected before and 3, 6, 9, 12, and 24 hour after the injetion. Serum concentrations of LH were assayed with a commercial LH kit. In control and TG women, P injection induced a surge-like LH secretion, but LH levels before P injection in TG women were slightly lower than in control women. In 2 of 3 TS women, P injection decreased LH levels, not inducing a surge-like secretion. One TS woman showed a surge-like LH secretion similar to those in TG women. We conclude that there is a sex difference in the central mechanism controlling the surge of LH secretion even in humans. [Jpn J Physiol 55 Suppl:S214 (2005)]

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Sexual differentiation of the brain is regulated by the action of steroid hormones on target tissues during critical periods. These periods are associated with peaks of testosterone secretion in males to differentiate the brain sexually. We determined whether the proliferation of the neural stem cells (NSCs) during critical period contribute to the formation of the sexually dimorphic nucleus (AVPv, SDN-POA, BSTpr, SCN, VMH and MePD) or not. Neonatal rats were treated with 5-bromo-2'-deoxyuridine (BrdU; 100 mg/kg) 12 h, 24 h and 36 h after birth because testosterone secretion peaks occur 2 h after birth. Neonatal rat brains were removed on postnatal day 3 (P3) and were processed for Nissl staining or immunohistochemistry for BrdU. We found that the number of BrdU-labeled cells in the BSTpr and MePD was significantly higher in males than in females, which may lead to sexual differentiation of the brain during the development. These results suggest that the sex difference in proliferation activity of NSCs in BSTpr and MePD may result in the difference in the nuclear volume in the BSTpr and MePD in adulthood. [Jpn J Physiol 55 Suppl:S214 (2005)]

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In the liver of new born rats, the rate of DNA synthesis is very high and decreases to very low in the adult. The hepatic cells in the adult are thought to be present in the G₀ phase (or G₁ arrest) in the cell cycle. After 70% partial hepatectomy (PHx), the cells in the remnant liver reenter the cell cycle. They pass through G₁ phase, complete S phases (DNA synthesis) and enter M phase (cell division). Efforts have been made to identify the triggers that induce the hepatic cell proliferation after PHx. Some cytokines or growth factor such as IL6 or HGF are nominated as candidates for triggers , but molecular mechanisms of the trigger action are not identified yet. In the course of liver regeneration, expressions of immediate early genes are well documented, however, analyses of gene products in the early time period after PHx are not clearly understood. In the present experiment, we tried to pick up protein species that fluctuate during the liver regeneration after PHx using SELD-proteinchip system®. We detected several proteins those concentrations were increased or decreased after PHx. As for the protein concentrations were increased, four kind of protein species that reached a maximum successively at thirty minutes, 1 hour, 2 hour or 4 hour after PHx were identified. The protein that concentration was increased 4 hours after PHx was identified as the gene product of growth-related immediate early gene PC3/hep1. These findings may find a clue to understand the molecular events that occurred in hepatic cells during the course of liver regeneration. Identification of proteins obtained are now underway. [Jpn J Physiol 55 Suppl:S214 (2005)]

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The most studies have estimated the neural differentiation of neural stem cells (NSCs) by examining the neuron-specific maker protein expression. In the present study, we examined the functional differentiation of NSCs by electrophysiological recording using Multi-channel Extracellular Recording System (MED System) and measuring concurrent gene expression of several proneural bHLH transcription factors. The NSCs derived from the striatum of E15.5 mice were cultured by neurosphere method using EGF (20 ng/ml) as a mitogen. The NSC differentiation were induced by 1% FBS and the spontaneous action potential of cells were recorded through day 1 to day10 after the differentiation induction. Furthermore, the relative amount of proneural bHLH transcription factor mRNA (Ngn1, Ngn2, Mash1, Math3 and Math5) were measured by RT-PCR. Neurons from NSCs started to show firing 3 days after differentiation induction. Moreover, the number of action potential-recorded channels reached the maximum level 10 days after treatment. The gene expression of Ngn1, Ngn2 and Math3 increased transiently with peaks of 24 hours after. On the other hand, Math5 gene expression gradually began to increase from 3 days after the differentiation induction. The time course of Math5 gene expression was parallel to those of action potential. Thus, Math5 might play an important role in the functional differentiation of the NSCs. [Jpn J Physiol 55 Suppl:S215 (2005)]

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Glucagon-like peptide-1 (GLP-1) is secreted by L-cells in the mucosa of the ileum and colon in response to nutrient ingestion, and intravenous (iv) or intracerebroventricular (icv) administration of GLP-1 inhibits feeding behavior of rodents. Administration of GLP-1 (50 pmol-20 nmol, iv) elicited dose-dependent increases in the rate of whole body O₂ consumption (VO₂), an index of thermogenesis, and heart rate of urethane-anesthetized rats. The colonic temperature increased up to 0.3°C without accompanying alteration of tail skin temperature. Icv administration of GLP-1 induced a slower and smaller increase in VO₂ than the intravenous administration. Decerebration had no effect on the thermogenic responses induced by the iv administration of GLP-1, suggesting no contribution of the forebrain to these responses. However, cervical spinal transection greatly attenuated the responses, suggesting the critical involvement of the lower brainstem. Adrenalectomy or pretreatment with an autonomic ganglion blocker, hexamethonium, or a β-adrenergic blocker, propranolol, also significantly attenuated the thermogenic response. However, subdiaphragmatic vagotomy or celiac ganglionectomy had no effect. Rats made insulin-deficient by pretreatment with streptozotocin also exhibited the normal thermogenic response to GLP-1. These results suggest the involvement of the GLP-1 in postprandial thermogenesis, mediated by the lower brainstem and sympathoadrenal system. [Jpn J Physiol 55 Suppl:S215 (2005)]

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The levels of plasma HDL-cholesterol and apoA-I in NFkappaB p50 subunit-deficient mice were significantly higher than those in wild-type mice under regular and high-fat diets, without any significant difference in the level of total cholesterol. To examine the role of NFkappaB in lipid metabolism, we studied its effect on the regulation of apoA-I secretion from human hepatoma HepG2 cells. LPS-induced activation of NFkappaB reduced the expression of apoA-I mRNA and protein, while adenovirus-mediated expression of IkappaB alpha super-repressor ameliorated the reduction. This IkappaB alpha-induced apoA-I increase was blocked by preincubation with MK886, a selective inhibitor of PPARalpha, suggesting that NFkappaB inactivation induces apoA-I through activation of PPARalpha. To further support this idea, the expression of IkappaB alpha increased apoA-I promoter activity, and this increase was blocked by preincubation with MK886. Mutations in the putative PPARalpha-binding site in the apoA-I promoter or lack of the site abrogated these changes. Taking these results together, inhibition of NFkappaB increases apoA-I and HDL-cholesterol through activation of PPARalphain vivo and in vitro. Our data suggest a new aspect of lipid metabolism and may lead to a new paradigm for prevention and treatment of atherosclerotic disease. [Jpn J Physiol 55 Suppl:S215 (2005)]

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We recently reported an involvement of brain angiotensin II (ANG II) and AT1 receptors in the development of the brain interleukin-1 (IL-1) production induced in rats by an intracerebroventricular (i.c.v.) injection of lipopolysaccharide (LPS) in vivo. In the present study, we used the primary culture of cytokine-producing microglia to investigate whether ANG II contributes to LPS-induced microglial activations through its effect on the activation of proinflammatory transcription factors, NF-kB and AP-1. We examined the production of IL-1 and NO, and morphological changes of microglia for its activation. LPS-stimulated microglia showed increases in IL-1 and nitrite concentrations, and transformation from round to process-bearing microglias, the effects being significantly inhibited by treatment with AT1 antagonist. The activity of NF-kB and AP-1 was enhanced in LPS-stimulated microglia, that were significantly suppressed by AT1 antagonist. These results suggest that microglia is involved in the mechanism underlying the enhancement by ANG II of cytokine production in the brain in vivo, and that ANG II enhances microglial activities (production of IL-1 and NO, and morphological changes) through the stimulation of microglial receptor, AT1, which evokes activation of transcription factors, NF-kB and AP-1. [Jpn J Physiol 55 Suppl:S216 (2005)]

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It is known that zinc deficient (ZnX) rats enhance their preference to sodium solution (Komai et al., 2000). In the present study, we conducted behavioral and electrophysiological experiments to investigate whether taste play a role for this situation or not. Results were as follows; (1) In the long-term (48 h) two-bottle preference test, the preference percents to 0.1 and 0.3M NaCl in the ZnX rats were higher than those in the control rats. But in the short-term (10 min) test, there was no significant difference in the preference percents between ZnX and control rats. (2) There was also no significant difference in the neural responses of chorda tympani nerves to sodium solution between ZnX and control rats. These results suggest that taste may not play a role for enhancement of preference to sodium in zinc deficiency animals. [Jpn J Physiol 55 Suppl:S216 (2005)]

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Long-term cold exposure causes increase in non-shivering thermogenesis to maintain body temperature. The energy metabolism changes remarkably. It results in increase in food intake, inhibition of increase in body weight and increase in mass of brown adipose tissue (BAT) with morphological changes. Changes in morphological appearance of liver were also observed during cold acclimation. In Zucker fatty rats, food intake did not increase and weight-reducing effect was more conspicuous during cold acclimation. Changes in liver and BAT during cold acclimation differ from those in lean rats. To analyze the mechanism of adaptive changes in Zucker fatty rats during cold acclimation, proteins of liver and BAT induced by cold acclimation were analyzed and they were compared with those of lean rats. Methods: Male Zucker fatty rats and lean rats were housed at 25°C or 10°C for 11 weeks. The liver and interscapular BATs were dissected and immediately frozen. Proteins were analyzed by 2D-PAGE and identified using MALDI-TOF mass spectrometry after in-gel digestion of the proteins. Results: During cold acclimation, approximately 60 different proteins in BAT were changed. They were classified into proteins related to energy metabolism, stress proteins and others. Some proteins related to carbohydrate metabolism were changed in the liver during cold acclimation. Expressions of proteins in these tissues were somewhat different between Zucker fatty rats and lean rats. [Jpn J Physiol 55 Suppl:S216 (2005)]

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We examined the effect of microinjection of orexin into the hypothalamus on tissue glucose uptake in unanesthetized rats or mice, assessing in vivo by 2-[³H]deoxyglucose (2DG) method. Microinjection of low dose of orexin A (5 pmol) into the medial hypothalamus increased the net uptake of 2DG in skeletal muscle (soleus, red part of gastrocnemius) and heart, but not in brown or white adipose tissue, 2 hours after the injection. These effects of orexin A were not observed when injected into other hypothalamic areas such as paraventricular and lateral hypothalamus. 2DG uptake in response to i.v. insulin was also enhanced in muscle (1.4-2.3 fold) six hours after the injection of orexin A into the medial hypothalamus. In order to explore the mechanism of orexin A-induced glucose uptake in muscle, we examined the role of the sympathetic nervous system. Hypothalamic orexin A increased norepinephrine turnover in skeletal muscle and heart preferentially. Furthermore, pretreatment with guanethidine abolished 2DG uptake by skeletal muscle in response to orexin A. Microinjection of low dose of orexin A (5 pmol) into the medial hypothalamus did not change spontaneous motor activity and food intake of these animals. These results suggest that hypothalamic orexin A plays an important role of glucose uptake and insulin sensitivity in skeletal muscle and heart. These effects appear to be at least partly mediated by the medial hypothalamus-sympathetic nervous system. [Jpn J Physiol 55 Suppl:S216 (2005)]

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An investigation on the effects of age and the relationship between plasma leptin concentration and fat weight in iron deficiency anemia was conducted on male Wistar rats, age 3 weeks weighting 40 to 50 g and 15 weeks weighting 330 to 350 g. The rats were fed either an iron deficient diet containing about 3 ppm Fe or a control diet containing about 358 ppm Fe in the form of ferric citrate and distilled water ad libitum for 8 weeks. The animals are divided into 4 groups with their diet intakes and body weights measured weekly. Plasma leptin concentration and blood characteristics were measured in 8 weeks after initial observation were conducted. Body weights, diet intake, RBC, Hb, Hct, MCV and serum Fe of the group kept on the iron deficient diet from 3 weeks old were less than those of the group kept on the control diet of the same aged group. Similarly, body weights, MCV and Fe level of the group kept on an iron deficient diet from 15 weeks old (15w-iron) were less than that of the group kept on the control diet of the same aged group (15w-cont). There was no change in the diet intake, RBC, Hb and Hct between the 15w-iron and 15w-cont groups. However, plasma leptin concentration showed significant correlation with fat weight in both groups (R²=0.804) with a regression line of y=0.59x-1.96, with the slope its line in the group kept from 15 weeks old being sharper than that in the group kept from 3 weeks. Present results suggest that the responsiveness of plasma leptin concentration to fat weight becomes augmented as the rats' age. [Jpn J Physiol 55 Suppl:S217 (2005)]

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Previously, studies in our laboratory have demonstrated that transforming growth factor-beta (TGF-beta) which was activated in the brain during exercise suppressed the spontaneous motor activities of mice. This suggested that TGF-beta in the brain contributes to the emergence of a feeling of fatigue. However, it has not clarified yet on which site activated TGF-beta acted in the brain. It seemed very important to identify where TGF-beta acts in order to elucidate the role that TGF-beta plays in the manifestation of central fatigue. Three types of TGF-beta receptors (TbR) have been identified so far. Several studies indicated that type 1 and type 2 receptors were the signaling components. Type 1 and type 2 TbR mRNA expressions were found in all brain regions. However high intensity of TbR protein immunoreactivity especially type 1 receptor was found in the paraventricular hypothalamic nucleus (PVH). Although TbR protein was found in neuronal cell bodies, it has not been reported that TGF-beta induced neuronal activation. Therefore, with Ca2⁺ imaging we investigated whether TGF-beta could activate neurons. In neuronal cells acutely dissociated from hypothalamus, we found TGF-beta responsive cells that increased cellular Ca2⁺ concentration in response to TGF-beta stimulation. Since PVH is important component in the regulation of neuroendocrine, behavioral and autonomic functions, it is reasonable that PVH is related to central fatigue induced by TGF-beta. [Jpn J Physiol 55 Suppl:S217 (2005)]

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At cenothermia the carbons molecules in glucose and other energy substrates are utilized in cellular metabolism and biosynthesis. In hamsters, a hibernation bout lasts for a week and during this time body temperature is maintained at 6 °C and whole body metabolism is reduced by 98%. Hibernating hamsters maintain sensory vigilance to hypercapnia, environmental temperature and external tactile stimulation yet many sensory and organ functions are suppressed. However during hibernation, cellular biosynthesis appears to cease globally because initiation of protein, mRNA and DNA synthesis stops. These specialized adaptations suggest the existence of hibernation specific metabolic pathways that, unlike cenothermic metabolic pathways, do not have a component that includes cellular biosynthesis. We investigated in vivo glucose metabolism in de-proteinated homogenates of brain, liver, brown fat, heart, muscle and blood from hibernating hamsters using ¹³C nuclear magnetic resonance spectroscopy. Preliminary results demonstrate that plasma glucose concentration is actively regulated during the hibernation bout with uptake of intravenously infused ¹³C-glucose (200mg/kg) occurring continuously during 60 hr of the hibernation bout. Tissue metabolic products derived from ¹³C-glucose metabolism are being determined. This study was supported by JSPS Grant-in-Aid for Scientific Research (B) 16390057 to MH. [Jpn J Physiol 55 Suppl:S217 (2005)]

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In this study, I investigated the influence of inhaling un-sensible fragrance which remained below sensory threshold on the autonomic nervous system by power spectral analysis of R-R intervals of heartbeats. 6 volunteers were chosen as the subjects by the reason that they felt sensible fragrance generated from 3000ppb aqueous R-linalool comfortable. The subjects were smelled three kinds of fragrance, control(without R-linalool), sensible(30ppb aqueous R-linalool), un-sensible(depended on the volunteers). R-R intervals were measured while subjects were sitting and keeping their respiration at a constant rate. When the subjects inhaled sensible fragrance, a significant increase was observed (P<0.05) in spectral integrated values (areas under the curve) of high frequency power (high component, HC). On the other hands, when the subjects inhaled un-sensible fragrance, this increase of HC, indicating the dominational parasympathetic nervous system, was not detect. These results suggest that there is relaxation effect in sensible fragrance of R-linalool, but not in un-sensible fragrance of R-linalool. In other words, some effects that generate by aroma therapy may be no more than the change of feeling given by fragrance. [Jpn J Physiol 55 Suppl:S217 (2005)]

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To examine the difference of thermoregulatory responses in upper- and lower- body work in healthy male volunteers in the hot environments, we observed thermal responses during cycle (BE) and arm crank (AC) exercises due to different criteria of work intensities, 1.2 l/min oxygen uptake (VO₂, Exp 1) and percent of maximal heart rate (%HR_max, Exp 2). Tympanic (T_ty) and skin (T_sk) temperatures, skin blood flow (SkBF), local sweat rate (LSR) and heart rate (HR) were continuously measured. In Exp 1, seven male subjects performed BE and AC of 40 min in a chamber with T_a of 32°C (rh, 50%). Increase of T_ty (DT_ty), SkBF and HR in the AC were significantly higher than those in the BE. No significant differences were observed in LSR, T_ty, mean T_sk and metabolic rate. In contrast, work efficiency was significantly higher in the BE than in the AC. In Exp 2, we examined difference of thermal responses during BE and AC under heat stress (34°C, rh, 45%) in seventeen males. They completed three consecutive sessions (rest, 30-40 and 60-70% of%HR_max) for 10 min. Final T_ty, DT_ty and T_sk in BE were significantly higher than those of AC. SkBF was significantly higher in AC than in BE at the initial and final stages of the exercise. We found that effector responses to loss heat due to sweating and SkBF was likely to dependence of percent of maximal oxygen uptake and in upper and lower-body work with identical%HR_max, T_ty and T_sk and sweating in the leg work are markedly increased. The present study suggests that there are differential effector responses between the upper- and lower-body work, based on relative work intensities. [Jpn J Physiol 55 Suppl:S218 (2005)]

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Cold constitution is a condition in which the patient feels uncomfortably chilly especially the fingers, legs, and waist. A number of Japanese women have this condition. Cold constitution might be mainly related to the disorder of autonomic nervous system and a lack of female hormone. We investigated the relationships between the peripheral circulatory function evaluated by the accelerated plethysmogram (APG) and the cold constitution in female students. The measurements of the APG in fingers were performed, using a plethysmography (Futurewave, Japan). The APG waveforms were classified into seven types (A∼G). Type A might be considered to be a good circulation, but type G, a poor circulation. In addition, the APG score was also calculated. Four hundred and fourteen students (mean age of 19.6±0.8 yrs.) participated in this study. About a half of the females (n=200; Cold group) recognized the existence of cold constitution. Furthermore, the Cold group was divided into three subgroups (weak; n=161, medium; n=30, strong; n=9), dependent on the conditions. In general, the females without the cold constitution (Normal group) belonged to the types of good circulation (type A, B), and higher APG scores. However, there were many females having the types of poor circulation and lower APG scores in Cold group, compared to Normal group. Among the Cold group, the females who have poor waveforms and lower APG scores tended to have severe cold constitution. These findings suggest that the existence and the degree of cold constitution are, at least in part, able to be evaluated by the APG. [Jpn J Physiol 55 Suppl:S218 (2005)]

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Fever is mediated by prostaglandin E₂ (PGE₂) produced in brain endothelial cells. Among PGE₂-synthesizing enzymes, the roles and cellular localization of cyclooxygenase-2 (COX-2) and microsomal-type PGE synthase (mPGES) in fever are well established. However, the type and localization of phospholipase A₂ (PLA₂) working in the upstream of COX-2 is unknown. We here show a possible involvement of calcium-independent PLA₂ (iPLA₂) in LPS-induced fever and other inflammatory responses. Male rats pretreated with an inhibitor of iPLA₂ (BEL, 20 mg/kg, i.p.) showed significantly suppressed fever response to LPS (10 μg/kg i.v.) administered 2 h later. PGE₂ concentration in the cerebrospinal fluid sampled 2 h after LPS injection was significantly lower in BEL-treated rats than that in vehicle-treated rats. Subarachnoidal blood vessels isolated from BEL-treated rats 2 h after LPS injection and incubated ex vivo released less amount of PGE₂ than those from vehicle-treated rats. LPS-induced expression of COX-2 and mPGES in brain endothelial cells were suppressed in BEL-treated rats. Moreover, plasma levels of inflammatory cytokines such as IL-1β and TNFα were also lower in BEL-treated rats. These results suggest that iPLA₂ is involved in fever and brain PGE₂ production in response to LPS. Contrary to our initial expectation, iPLA₂ seems to play a proinflammatory role in the earlier stage of LPS-induced responses rather than just upstream of COX-2 in brain endothelial cells. [Jpn J Physiol 55 Suppl:S218 (2005)]

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Our laboratory has reported that TGF-beta in the brain was activated during swimming exercise and that the intracranial administration of TGF-beta suppressed the spontaneous motor activities in rats and mice. However, little is known about the effects of regulation of central TGF-beta on energy metabolisms of peripheral tissues. After injection of TGF-beta into cisterna magna of the rat, respiratory exchange ratio immediately decreased, that meant the increase in the fat oxidation and decrease in the carbohydrate, while energy expenditure didn't change significantly. To elucidate in particular the mechanisms of the increase of fat oxidation, we collected the blood via cannulae implanted beforehand in the right atrium of heart, postcaval vein, and hepatic vein of rats at scheduled time points after intracranial administration of TGF-beta under isoflurane anesthesia and analyzed the samples. In consequence, the output of ketone body from the liver significantly increased just after the administration and that of nonesterified fatty acid from the lower body increased after 30min. No significant changes were observed in the concentration of glucose and lactate in plasma and those of glycogen in the liver and skeletal muscles. These results are of very interest because TGF-beta in the brain exclusively changed the concentration of substrates relevant to fat metabolism without affecting those to carbohydrate. [Jpn J Physiol 55 Suppl:S218 (2005)]

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Fever is mediated by prostaglandin E₂ (PGE₂) in the brain. Fever-causing PGE₂ is produced through the enzymatic actions of cyclooxygenase-2 (COX-2) and microsomal PGE synthase-1 (mPGES-1). In rats, COX-2 and mPGES-1 are co-induced in brain endothelial cells during fever. However, it remains unclear if the results in rats could be generalized to other species. We, therefore, immunohistochemically localized COX-2 and mPGES-1 in mouse brain, and also examined PGE₂ production in isolated brain tissues. Similarly to rats, COX-2 was induced in brain endothelial cells in mice 3 h after lipopolysaccharide (LPS) intraperitoneal injection. On the other hand, mPGES-1 was not induced there but was constitutively expressed in leptomeninges (LM) and choroid plexus (CP). In LM, COX-2-immunoreactive (ir) endothelial cells were located in the vicinity of mPGES-1-ir non-endothelial cells. When incubated ex vivo, a complex of LM-subarachnoidal blood vessels from LPS-treated mice produced significantly higher levels of PGE₂ than that from saline-treated mice. PGE₂ biosynthesis in this tissue was almost completely eliminated by COX-2 inhibition or mPGES-1 gene disruption. In CP, mPGES-1-ir non-endothelial cells were found adjacent to COX-1-ir endothelial cells. However, CP produced low levels of PGE₂ even in those from LPS-challenged mice. These results indicate that COX-2 and mPGES-1, which are expressed in distinct cellular groups in mouse brain, are necessary for LPS-induced PGE₂ biosynthesis, and implicated that PGE₂ is biosynthesized in a transcellular manner. [Jpn J Physiol 55 Suppl:S219 (2005)]

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In our previous study, we reported that the radiation increased skin blood flow and influenced exercise duration during exercise in the heat. In the present study, we identified the main factor limiting exercise duration in the heat, especially in the condition included radiation. To assess this problem, we investigated the relationship between temperature responses and exercise duration. Some healthy male subjects dressing shorts remained seated resting for at least more than 40 min, and performed 20 min or more of cycle ergometer at several intensities in climatic chamber (Ta = 33°C, 40%RH). The dorsal aspect of trunk was irradiated by infrared heater with main emissivity intermediate-infrared (MIR; 1.5-5.8μm) regions. Esophageal (Tes) and skin (Tsk) temperatures, heart rate (HR) were measured continually throughout the experiment. Expired air was collected for calculation of oxygen consumption (VO₂). Significant effects of radiation were observed on Tsk at irradiated region and exercise duration. Tes at the end of exercise was significantly related to increase in exercise performance time (r=0.71, p<0.05) in a trial with radiation. This study demonstrates that there is an influence of radiation on exercise duration and that a factor limiting exercise duration may be Tes in a hot environment with radiation. [Jpn J Physiol 55 Suppl:S219 (2005)]

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Hamsters arousing from hibernation demonstrate pronounced regional heterothermy with the rostral half of the body warming faster than the caudal half. This heterothermy probably involves restriction of the blood supply to the caudal half of the body. We investigated the mechanisms controlling regional heterothermy during arousal from hibernation. We used laser Doppler flowmetry to measure hind-foot blood flow and gamma imaging of technetium labeled albumin to measure blood volume distribution in hamsters arousing from hibernation. Hibernating hamster responded to mechanical stimulation with rapid reduction (73%) of hind foot blood flow suggesting peripheral vasoconstriction, and the vasoconstriction was maintained from the onset of arousal until late in arousal when rectal temperature is rapidly increased. Alpha-adrenergic blockade early in arousal increased hind-foot blood flow by 700%. Gamma imaging revealed that by the early phase of arousal from hibernation, the blood volume of the body below the liver is greatly reduced while that of the thorax and head is much greater than in anesthetized hamsters. As arousal progresses and cardiac activity increases, this pattern of regional blood volume redistribution is largely maintained however blood volume slowly decreases in the thoracic region and slowly increases in shoulder/head regions. The last stage of arousal is characterized by a reduction in sympathetic tone in the hind body that results the movement of warm blood into the caudal half of the body and a compensatory reduction of blood volume in the neck and head regions. [Jpn J Physiol 55 Suppl:S219 (2005)]

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We recently demonstrated that two experimental groups exposed to alternatively changing ambient temperatures (ACAT, repeated temperature changes between 4°C-1h and 27°C-1h) and constant ambient temperature (CAT, 4°C) exhibited significantly higher levels of plasma corticosterone than the control group (25°C). Moreover, levels of plasma corticosterone in the ACAT group were higher than the CAT group at 1, 2, 4 and 10 days after the exposure. We concluded that frequently changing, but not constant, ambient temperature may have induced a stronger stress in the rats. The purpose of this study was to examine the influence of stress induced by exposure of differing ambient temperatures on the mechanism of cell-mediated immunity in rats. We analyzed whether fever caused by the intraperitoneal injection of LPS was different between the ACAT and CAT groups. It was found that LPS-induced fever in the ACAT group was significantly higher than the CAT group. Enhanced fever in the two groups was maintained even after corticosterone returned to the control levels during 24h exposure at 25°C. The present results may suggest that enhancement of LPS-induced fever was larger when stress in terms of corticosterone was stronger. [Jpn J Physiol 55 Suppl:S219 (2005)]

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The main pathway of ethanol metabolism in the liver is known to involve a 1-st oxidation step of ethanol to acetaldehyde via alcohol dehydrogenase (ADH) followed by a 2-nd oxidation step of acetaldehyde to acetate by aldehyde dehydrogenase (ALDH). ADH and ALDH activities in rats are affected by nutritional or dietary status. Further, fasting decreases the rate of liver ethanol metabolism in vivo. However, the age-related effects of fasting on liver ADH and ALDH activities are not sufficiently understood. Therefore, the age-related effects of fasting on rat liver cytosolic ADH and mitochondrial ALDH activities were studied in infant (3wks), adult (8wks) and aged (32wks) SD male rats. Fasting on infant, adult and aged rats were maintained for 2, 5 and 13 days, respectively. Total cytosolic ADH activities per body weight in fasting (FAS) group were 0.46-0.60 times significantly lower than those in control (CON) group in three life stages. Mean decreased rates of ADH activities were in the following order : infant >> adult>aged rats. Total mitochondrial ALDH activities per body weight in FAS group were 0.38-0.54 times lower than those in CON group in three life stages. Mean decreased rates of ALDH activities were in the following order : adult>infant≥aged rats. In conclusion, fasting-induced decreased actions of rat liver cytosolic ADH and mitochondrial ALDH activities are age-dependent and the decreased actions are associated with the age-related difference in turnover of ADH and ALDH molecules. [Jpn J Physiol 55 Suppl:S220 (2005)]

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Food intake causes the dramatic change of metabolic patterns. Further, remarkable changes of metabolism occur in each developmental stage. However, the age-related effects of fasting on lipid metabolism, which plays a crucial role in supplying most of the energy, are not understood. Therefore, plasma total ketone body, β-hydroxybutyrate, acetoacetate, free fatty acid, triglyceride levels, and white adipose tissue levels in infant (3 wks), adult (8 wks) and aged (32 wks) Sprague Dawley male rats were investigated. Fasting of infant, adult and aged rats were maintained for 2, 5 and 13 consecutive days, respectively. Plasma total ketone body, β-hydroxybutyrate, acetoacetate and free fatty acid concentrations in three life-stage rats were increased significantly during fasting. The increased patterns of plasma ketone body and free fatty acid levels during fasting were larger in the order of aged, adult and infant rats. These results show that the magnitudes of ketone body and free fatty acid levels mobilized into plasma during fasting were clearly age-dependent. Further, the weights of perirenal and periepididymal white adipose tissues in three life-stage rats were significantly lower in fasting group than in control group. Mean decreased rates of two adipose tissues during fasting were in the order of infant, adult and aged rats. In conclusion, fasting-induced lipolytic actions are age-dependent and closely related to the differences in metabolic turnover rate and the energy storage in the body in each life-stage. [Jpn J Physiol 55 Suppl:S220 (2005)]

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It is well known that thermoregulation is different between male and female, although the mechanism remains unclear yet. The purpose of this study is to investigate the role of estrogen on thermoregulatory mechanisms for daily change of body temperature (T_b). Fist, we measured daily changes in Tb, metabolism, and body surface temperature in gonadectomized male and female rats (n=6 each) under 12:12h light-dark condition. Compared with normal rats, T_b in the female gonadectomized rats became unstable, showing 2-4 h irregular small oscillation, although chi-square analysis indicated that the period of the rhythm remained 24 h. However, there was no change in the T_b rhythm in the male gonadectomized rats. Second, silicon tubes containing E2 crystalline were subcutaneously implanted in the gonadectomized rats. In the female gonadectomized rats with the tubes, the T_b rhythm was restored to the normal pattern. However, there was no influence of E2 on the T_b rhythm in the male rats. The T_b change due to the gonadectomy is closely linked with both metabolism and body surface temperature. These results indicate that E2 is involved in the thermoregulation for daily change of T_b in female rats, but not in male rats. We also hypothesized that central neurons reacting both thermal and E2 stimuli would be closely associated with the mechanism. Therefore, histological analysis was conducted to test the hypothesis. [Jpn J Physiol 55 Suppl:S220 (2005)]

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The venous plexus in the spinal canal is an extensive vascular network that is valveless and extends along the entire length of the vertebral column. It parallels, joins and at the same time bypasses the longitudinal veins of the thoracic and abdominal cavities, and then unites the superior and inferior vena cava. The spinal column is a strong structure that protects its contents from the direct effect of intra-thoracic and intra-abdominal pressure changes and also protects the epidural venous plexus. Thus, the blood flow in the internal vertebral venous plexus is supposed to be in either direction depending on the changes of the intra-thoracic, intra-abdominal pressures and posture. However, little attention has been paid on the physiological role of the venous plexus. During lower leg exercise, blood flow to active muscles increases greatly. The blood passed through the muscles should be warmed and the blood with the highest temperature in the body returns to the heart. If some part of the venous blood would be conveyed through the vertebral venous plexus, it could warm the spine, which is one of the components of the thermoregulatory center, and induce thermoregulatory responses in the lower body. To assess this hypothesis, we investigated how venous blood from the leg returned to the central venous system by direct venography with magnetic resonance imaging. [Jpn J Physiol 55 Suppl:S220 (2005)]

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Free radical and reactive oxygen species (ROS) are involved in pathogenesis of several diseases, including artherosclerosis, chronic inflammatory diseases, and cancer. Therefore, the body possesses several antioxidant systems that are very important for the prevention of oxidative stress. We previously proposed a new simple 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay to evaluate the total FRSA in saliva. In the present study, we designed three different experiments as follows. 1 Total FRSA in saliva was determined by both DPPH method and AOP-490^TM general method using the reduction of copper. 2 FRSA in saliva sample and in serum sample of 21 healthy human volunteers ranging in age 20 to 26 years were measured by DPPH method. 3 Daily variation (circadian rhythm) in FRSA of three volunteers (male, 26 years; female, 34 years; female, 50 years) was evaluated by DPPH method at 30 min interval during am 6:00 to pm 11:00.In the result from Exp 1, the linear regression curve with the positive correlation (r= 0.768) were obtained between DPPH method and AOP method. Finding from Exp 2, showed also a positive correlation (r= 0.770) between saliva and serum, suggesting that FRSA in saliva is responsible for that in serum. From findings of Exp 3, eating and drinking or relaxation of stress increased FRSA and fatigue of working and exercise decreased it. In conclusion, DPPH measurement in saliva is simple, reproducible, and easy, and therefore, the monitoring of physical and mental stress might be reasonably expected by this method. [Jpn J Physiol 55 Suppl:S221 (2005)]

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The sensation related to temperature is complex in that there are two different kinds of sensation, subjective “thermal comfort” and objective “temperature sensation”, and in that we feel local as well as whole body sensations. And it is not clear how these different sensations are related with each other. To investigate this question we developed a new system to measure the distribution of whole body skin temperature and the two sensations in human. Skin temperatures (Tsk) of in total 50 points on both sides of the body were measured by thermocouples, and local heat flux was also measured at 25 points by heat flux sensors. Core temperature (Tcore) was measured by telemetric system (CoreTemp), the transmitter of which was swallowed by a subject. Temperature sensation (cold-neutral-hot) and thermal comfort (uncomfortable-neutral-comfortable) of 25 points of body surface, and those of the whole body were reported by the subject using a console with 52 dials for each sensation. Color-coded Tsk and sensations were displayed on the computer display. This system enables to see the distribution and change of Tsk and sensations over the body surface even with clothes on, and should be useful for the analysis of temperature-related sensations as well as the design of comfortable environment or clothes. [Jpn J Physiol 55 Suppl:S221 (2005)]

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Higher sweating in trained, compared to sedentary men has been attributed to differences in the peripheral sweating mechanisms, although such mechanisms have not been completely investigated in comparative terms. The aim of this study is to quantitatively investigate the peripheral sudomotor adaptive mechanisms attributed for greater sweating in endurance-trained athletes as opposed to sedentary men. To do this, we compared sudomotor activities to acetylcholin iontophoresed in the fore arm skins of trained versus untrained subjects. Directly activated and axon reflex–mediated sweating during ACh 10% iontophoresis (2mA*5min) were measured by capacitance hygrometer (Quantitative sudomotor axon reflex test: QSART). Changes in skin and body temperatures, sweating rate (sweat volume), sweat onset time, active sweat gland density (SGD), and single sweat gland output (SGO) were measured. Training-related differences were observed for sweat volume, onset-time, SGD, SGO and skin temperature. It was concluded that endurance trained athletes had higher sweat outputs due to the combinations of a higher sweat output per activated sweat gland and higher number of activated sweat glands. [Jpn J Physiol 55 Suppl:S221 (2005)]

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This study evaluated the effects of stretches and massage on economy class syndrome in normal subjects. 24 subjects (male n=12, female n=12) were randomized (after informed consent) into three groups (control, CON; stretching group, ST; massage group, MA). The treatment groups received stretches or massage in person according to guide, 10minutes every hour for 10 hours. Blood and urine were drawn before and after 10-hr flight-situated perform. The results are as follows. No differences were observed in electrolytes, D-dimer, creatinine, urinal protein, renin-aldosterone among groups. But, increase in ankle circumference in CON was significantly larger than that in MA. These results showed that flight edema, not economy class syndrome, was induced by physical problem such as less activity, circulation difficulty, fluid accumulation, etc. Massage or stretching have a possibility of attenuating edema. [Jpn J Physiol 55 Suppl:S221 (2005)]

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Gene expression decreased in hypothalamus and thermoregulatory response under cold and psychological stress in genetically heat-tolerant rats Furuyama, F1., Oiwa T1., and Nishino H1.1Dept. Neuro-Physiol. Brain Sci, Nagoya City Univ. Grad. Sch. Med. Sci., Nagoya; 2Dept. Physiol., Shimane Med. Univ., Izumo; 3Dept. Nurs., Nayoro City Coll., Nayoro; The FOK rat is genetically tolerant to acute heat challenge and to cold, and in addition shows specific changes in lipid profile. We studied, in the present study, gene expression which decreased in hypothalamus, and in addition thermoregulatory response to cold and psychological stress in freely-moving FOK rats. The order of decrease in expression was IGFBP3 > collagen α1 type 1 > 12 lipoxygenase > serine protease inhibitor > zinc finger protein > 8-oxo-dGTPase. These results suggested that the decreased were genes involved in brain growth and mutation, and in inhibition of locomotor activity and anxiety. Psychological stress-induced fever was larger in FOK rats than those in the others. At 0°C, body temperature of rats increased up to 1°Cwith repeated large rise and fall. Period of rise and fall cycle in body temperature of FOK rats was shorter than those in the other strains. These results were coincident with the functional trends in genes of which expression increased in FOK rats in the previous report. [Jpn J Physiol 55 Suppl:S222 (2005)]

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Previous reports have clarified that mechanical load is an effective countermeasure against hindlimb unloading (HU)-induced functional changes in antigravity skeletal muscles. The purpose of this study was to investigate the effectiveness of isometric resistance exercise (IRE) to HU-induced atrophy and shift to the faster isoform of myosin heavy chain (MHC). Fischer-344 female rats (4-month old) were assigned to either weight-bearing control or HU group. HU-rats had their hindlimbs suspended for 3 weeks with or without IRE. IRE (stationary support on a cylindrical wire mesh with 60 or 80 degree incline) was performed three times daily. An additional weight of 50-70% body mass was hung from the rat's tail during IRE. Each training bout lasted 10 min, for a total of 30 min/day. Myofibrillar protein and MHC isoform expression were measured in the soleus (SOL), plantaris (PLA), and medial gastrocnemius (MG) muscles.HU-induced atrophy was greater in the SOL than in the PLA and MG. HU increased MHC IIb and IIx isoforms with a concomitant decrease in MHC I isoform in the SOL. In the PLA and MG, HU increased MHC IIb isoform with a concomitant decrease in MHC IIa and I isoforms. IRE protected HU-induced atrophy and shift of MHC isoform expression, especially in the fast PLA and MG. These results demonstrate that IRE leads greater protection from atrophy and shift of MHC isoform expression with HU in the fast-twitch muscle than in the slow-twitch muscle. [Jpn J Physiol 55 Suppl:S222 (2005)]

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The effects of aging on the renal function (RF) following exhaustive exercise are unknown. This study was conducted to investigate these effects on 352 healthy subjects after an exhaustive treadmill run. The subjects were of both sexes, aged 8–76 years. Urinary excretion of protein (uTP), blood lactate [bLA], blood pressure (BP), and creatinine clearance (Ccr) as an index of GFR were measured. Ccr significantly decreased directly after the exercise and recovered to the pre-exercise level 30–60 min later. In comparison with different generations, Ccr in males under 25 years of age decreased to 55.3% of the pre-exercise level directly after the exercise. In males 25 to 50 years old and those over 50, Ccr decreased to 68.8% and 86.9% of the pre-exercise levels, respectively. Similar levels of decrease in Ccr were shown in females directly after exercise. The net decrease in Ccr directly after exercise (%Delta;Ccr) at every 10-year interval was remarkable in the younger generations, and it lowered on aging. However, no difference of ΔCcr was found in subjects under 40 years of age. Net [uTP] measured 30 min after exercise lowered in relation to aging. A significant coefficient of correlation(r = −0.695, p < 0.001) was shown between ΔCcr and maximal heart rate (HRmax). The present results show that the younger the subjects, the longer he or she could run before exhaustion. Consequently, a remarkable decrease in Ccr, and more increases in BP, [bLA], and HRmax were induced after exhaustive exercises by the younger generations. [Jpn J Physiol 55 Suppl:S222 (2005)]

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It is known that endurance training leads to an increase in the ability of glucose transport. However, whether the utilization of exogenous glucose (exoGLU) is increased in the trained state is still remained controversial. This study was aimed to investigate effects of physical fitness on the oxidation of exoGLU during moderate exercise by using ¹³C glucose. Substrate utilization during 60 min of cycling at a work rate corresponding to 80% anaerobic threshold (W₈₀) was studied in 7 endurance trained subjects (T; W₈₀ 134±12 W) and 9 sedentary subjects (UT; W₈₀ 90±13 W). After fasting for more than 12 hours, subjects ingested 3ml/kg of 5% glucose solution containing 0.25% ¹³C labeled glucose just before the exercise. Substrate oxidation was calculated for the final 30 min-period of exercise. A higher rate of fat oxidation was observed in T compared with UT (4.2±1.9 vs. 1.9±1.2 mg/min/kg, p<0.05), whereas endogenous glucose and exoGLU oxidation rates were not different between T and UT. The exoGLU recovery rate was significantly higher in T than in UT (31.3±4.1 vs. 25.4±6.6%, p<0.05), reflecting higher energy expenditure in T during exercise at the same relative intensity. However, relative proportion of exoGLU oxidation to total energy was not significantly higher but rather lower in T than in UT (20.3±4.7 vs. 23.8±3.0%). It is concluded that T subjects do not have an increased exoGLU oxidation at W₈₀. The smaller reliance on exoGLU in T may be in part due to the increase in fat oxidation and/or the saving of muscle glycogen. [Jpn J Physiol 55 Suppl:S223 (2005)]

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Purpose: High intensity resistance exercise increases growth hormone (GH) secretion. Ghrelin has been discovered to stimulate the secretion of GH. The purpose of this study was to examine the effects of acute resistance exercise on circulating acylated ghrelin concentrations. Methods: In preliminary observations, 1-RM (repetition maximum) loads for lat pull down, squat and bench press were measured in 6 male subjects. The subjects performed three sets of 10 repetitions for each exercise (item) at 80% of a 1-RM with 60-s intervals, in experimental trials. Additionally, all subjects also rested during the same time of the day in control trials. Results: Serum GH concentrations were significantly increased immediately after the exercise, compared with pre-exercise levels. However, plasma acylated ghrelin concentrations did not change by the high intensity resistance exercise. Conclusion: This study suggests that circulating acylated ghrelin levels are not related to exercise-induced GH secretion. [Jpn J Physiol 55 Suppl:S223 (2005)]

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In earlier studies, we have shown that the ratio of the first derivative (dP/dt) of carotid artery pulse (CAP) to the blood pressure (P), CAP (dP/dt)/P, is an easily measurable, noninvasive index of cardiac contractility even in moderate exercise (Ifuku et al. 1994). Using this cardiac index, we aimed to examine the regulatory mechanism of cardiac function during a cold pressor test in athletes. Seventeen healthy subjects (9 athletes, 8 untrained subjects) were subjected to the cold pressor test according to Hines and Brown's method, which required them to immerse the right hand in chilly water (4°C) for 1 min. Although the mean blood pressure increased significantly during cold stress in both athletes and untrained subjects (P<0.05), the cardiac function of different groups changed in different manners. In athletes, the cardiac index and heart rate increased significantly (P<0.05), so that resultant cardiac outputs increased significantly (P<0.05). However, in untrained subjects, the index tended to decrease and heart rate decreased significantly (P<0.05), so that cardiac outputs decreased significantly (P<0.05). After the offset of immersion, the index and heart rate decreased significantly in untrained subjects (P<0.05). These findings suggest that the cardiac contractility and heart rate during a cold pressor test are enhanced in athletes, but depressed in untrained subjects. [Jpn J Physiol 55 Suppl:S223 (2005)]

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The purpose of this study was to investigate the effects of chronic voluntary exercise on blood adiponectin concentrations. Male Otsuka Long Evans Tokushima Fatty (OLETF) rats (26-week-old) underwent regular 12-week wheel running exercise (EX) and food restriction (FR) to the same reduction of body weight. In this study, both EX and FR induced the same reduction of body weight, abdominal fat volume and serum leptin concentration compared to ad libitum control rats. Although FR induced the increase in serum level of adiponectin, EX induced no change at the end of the study period. Serum testosterone levels were higher in EX rats compared to other groups, and there was a strong inversely relationship between serum level of adiponectin and testosterone for all groups. Our results suggested that 12-week voluntary wheel running exercise might induce different effects on the serum level of adiponectin compared to food restriction in spite of the same reduction in body weight, fat tissue mass and serum leptin concentration, and we speculated that the elevated serum testosterone concentration may set off the increasing effect on serum adiponectin concentration induced by weight and fat volume reduction in exercising rats. [Jpn J Physiol 55 Suppl:S223 (2005)]

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Purpose: The purpose of this study is to evaluate the relationship between physical fitness and dental health status in the 80-year-old population, followed-up five-years data. Methods: In 1998, physical fitness and oral health status were examined for 697 (275 male, 422 female) who were 80-year-old and for 207 (90 male, 117 female) among them in 2003. Informed consent was obtained. Hand-grip, leg strength, stepping rate and one-leg standing time were measured. Ability to chew the 15 foods was asked. Dental examinations were performed in the manner recommended by WHO. Results: At 80, the mean teeth was 8.1±9.0, the mean chewable foods was 11.6±3.6. At 85, 6.7±8.3, 10.6±4.1. The number of chewable foods was related significantly with the number of teeth. The number of chewable foods was positively related to leg strength and to one-leg standing time. The number of foods was correlated positively with all physical fitness test. A significant positive correlation was seen between the number of teeth and physical fitness test. When subjects were divided into four groups according to the number of chewable foods, or the number of teeth, hand-grip, leg strength, and one-leg standing time each increased significantly in groups with more foods chewed or more teeth. Conclusion: Chewing ability may be an independent predictor of physical fitness. [Jpn J Physiol 55 Suppl:S224 (2005)]

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We have reported an individual difference in exercise performance induced by artificially added dead space as a simulation method at high altitudes. The purpose of this study was to summarize the characteristics of circulation and respiration during repeated exercise testing with or without dead space. Healthy male students performed alternatively the graded sub-maximal exercise four times with or without additional horse, the volume of which was 820 ml to respiratory mask. The graded exercise testing using treadmill was started after interval for 30 minutes. The values of estimated maximal oxygen uptake with dead space were revision of wide range from 96 to 56 (mean: 80) percent of the maximal oxygen uptake without dead space as a control. These decreased values with dead space of 820 ml were equivalent to the reported values at an altitude of about 1,180–5,000 (mean: 3,340) meters. The observed individual percent of maximal oxygen uptake correlated negatively with the percent of ventilatory equivalent (expiratory gas volume / 100 mlO₂) with dead space/ control at above the low intensity of exercise, except that at rest. The individual regression line of heart rate and oxygen uptake shifted to the right by the effects of added dead space and repeated exercise testing. However, each value in percent of ventilatory equivalent was fixed with or without dead space, and it was not affected by repeated exercise testing. Therefore, it is necessary to analyze the ventiratory efficiency during exercise at high altitudes. [Jpn J Physiol 55 Suppl:S224 (2005)]

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The purpose of this study is to examine whether protein supplementation during 10-day aerobic training enhances the improvement of thermoregulatory capacity in young men. Fourteen subjects (age, 22 ± 4 (SD) yr; Vo_2,peak, 56.5 ± 4.4 (SD) ml/kg/min) were divided into two groups according to the composition of supplements; placebo (C, 0.0g protein/kg, n = 7) and protein (S, 0.18g protein/kg, n = 7). Subjects in both groups exercised on a cycle ergometer at 60% peak oxygen consumption rate (Vo_2,peak), 60 min/day, for 10 days, at 30°C of room temperature and 50% of relative humidity. They took protein or placebo within 30 min after exercise of each day. After training, Vo_2,peak increased by 5.1 ± 0.8(SE)% in S and 5.3 ± 0.8% in C, but with no significant differences between the groups. The esophageal temperature thresholds for forearm skin vasodilation and sweating were measured by having the subjects exercise with a cycle ergometer at pre-training 60% Vo_2,peak for 30-min in the same environment as during aerobic training. Both thresholds significantly decreased in S after training but not in C with significantly greater decreases in S than in C (P < 0.05). These results suggest that protein supplementation during 10-day aerobic training enhances the improvement of thermoregulatory capacity. [Jpn J Physiol 55 Suppl:S224 (2005)]

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We developed an endurance exercise training (ET) regimen by accelerometry to increase physical fitness for older people in the field. Three hundred older people aged ∼65 yr were divided into 3 groups (n= 100, each) according to ET regimens for 6 months: no-ET (C,), constant moderate velocity of walking (CMW), & low/ high velocity of walking (LHW). In CMW, subjects were oriented to walk at 40% of their maximal velocity (Vmax), for 60 min, above 5 days a wk, where steps was measured with a pedometer. In LHW, subjects were oriented to repeat10 sets of 3-min walk at 30% Vmax followed by 3-min walk at 70% Vmax, above 5 days a wk, where energy expenditure was monitored by accelerometry. Before & after ET, maximal isometric knee extension force (Fmax) was measured with Biodex, and peak aerobic power (VO2, peak) with cycle-ergometer. The daily steps and energy expenditure were electrically transported every 2 wks from terminals to a central computer through IT network. The number of subjects to accomplish the program was 10 in male (M) & 44 in female (F) for CMW, and 13 in M & 31 in F for LHW. Similarly, the number in C to keep sedentary life and receive the physical fitness tests was 5 in M & 39 in F. After ET, VO2, peak and Fmax increased by 8.6% (P<0.05) & 12.2% (P<0.01), respectively, in LHW, while remained unchanged in other groups (P>0.34). Thus, the low / high velocity of walking increases physical fitness in older people, which can be done by accelerometry & IT network. [Jpn J Physiol 55 Suppl:S224 (2005)]

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Skeletal muscles are capable of adapting themselves to a variety of exercise stimuli with varied changes in their mechanical and metabolic properties. Muscle hypertrophy is induced by stretching of matured muscles in vivo. On the contrary, muscle atrophy is induced by some models of reduced neuromuscular activity. However, little data are available for the intracellular changes of skeletal muscle hypertrophy and atrophy irrespective of a variety of techniques. Therefore, it is useful to use the β₂-agonist (clenbuterol : CLE)-induced muscle hypertrophy and whole body suspension (WBS)-induced muscle atrophy. Male SD rats were used and divided into the control (CON) groups and the CLE administered (ADM) or WBS groups. CLE (1mg/kg BW/day) was administered for 30 days. WBS was carried out for 10 days. SOL and GAS muscles were used for muscle RNA, DNA and protein assays. Protein/RNA ratios of both muscles increased by 16-19% in ADM group. Protein/DNA ratios of both muscles increased by 11-37% in ADM group. Protein/DNA ratios of both muscles decreased by 32-39% in WBS group. RNA/DNA ratios of both muscles decreased by 28-39% in WBS group. In conclusion, SOL muscle hypertrophy by CLE may be at least partly related to the increases in DNA transcription and protein synthesis (=RNA/DNA) and apparent cell volume (=Protein/DNA). WBS-induced muscle atrophy may be accompanied by the decreases in Protein/DNA ratio and RNA/DNA ratio without changing ribosomal capacity (=Protein/RNA). [Jpn J Physiol 55 Suppl:S225 (2005)]

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It is generally accepted that skeletal muscle atrophy is induced by hypokinesia and/or hypodynamia such as bed-rest, gypsum fixation, tenotomy, joint immobilization, suspensions and space-flight. On the other hand, skeletal muscle possessed multiple proteolytic systems, and cathepsin B is known to be one of the lysosomal proteases. Both the increased catabolism and decreased synthesis of protein in the muscles may be causally related to muscle atrophy occurring in suspension. Further, muscle atrophy may release muscle dipeptides, e.g., carnosine (CAR) or anserine (ANS). In the present study, therefore, the effects of whole body suspension (WBS) on the muscle protein, cathepsin B and dipeptide levels in rats were investigated. Male SD (n=24, 7wks old) rats were divided into the cage control (CON) group and WBS group. The WBS was carried out for 10 days. The relative weights of soleus (SOL) and gastrocnemius (GAS) muscles per BW were lower in the WBS than those in the CON. SOL and GAS muscle protein contents in the WBS were clearly lower than those in the CON. SOL muscle cathepsin B activities per BW were significantly higher in the WBS than in the CON. The WBS decreased muscle CAR concentrations in SOL and GAS muscles, and decreased muscle ANS concentrations in SOL muscles, compared with the CON. In conclusion, WBS-induced SOL muscle atrophy may be induced by increased breakdown of muscle proteins and/or decreased muscle buffering capacities. [Jpn J Physiol 55 Suppl:S225 (2005)]

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Strategies of humans with stress are divided into two major groups by means of the stress coping inventory (SCI) after Lazarus, i.e. an emotion-focused type (E-type) and a problem-focused type (C-type). We have examined whether responses to stress were different between college students with these two coping strategies. By means of SCI, coping styles of the college students volunteered were divided either into E-type or C-type. Cardiovascular and mucus immune responses to stress were compared between two groups. Waiting still for a sentence-completion test was regarded as an acute, passive stress. The secretion of secretory immunoglobulin A(sIgA) was decreased by the stress both in E-type and C-type students. However, covariance of heart beat intervals (CVPP) was decreased by the stress in C-type students but not in E-type students. A decrease in finger skin temperature, i.e. vasoconstriction of the cutaneous vasculatures, was observed only in C-type students. There was no difference in subjective reports on the strength of stress between two groups. In conclusion, acute, passive stress induced cardiovascular responses predominantly in C-type students, although caused a decrease in sIgA secretion both in E-type and C-type students. By these results, we have confirmed that stress responses are different between humans with different coping strategies with stress. [Jpn J Physiol 55 Suppl:S225 (2005)]

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We found in the previous experiments for the first time that lowering barometric pressure (27 hPa over 8 min) and lowering ambient temperature (7°C decrease from 22°C) intensify pain-related behaviors in rats rendered neuropathic or arthritic. We believe that these phenomena simulate weather-sensitive pain in humans, and some specific organs to sense barometric pressure must be present somewhere in the body. In the present study, the inner ear of rats rendered neuropathic was destroyed by an injection of arsenic (5 mg) into the middle ear to investigate the hypothesis that the barometric sensor is located in the inner ear. Neuropathy was made by a constriction injury on the sciatic nerve (CCI) or a spinal nerve (L5) ligation (SNL) in Sprague Dawley rats. To measure pain-related behaviors, innocuous (34.3 mN) and noxious (92.2 and 197.2 mN) bending force of von Frey filaments were applied ten times to the plantar skin, and the number of foot lifts (withdrawals) was counted. When the CCI and SNL rats were exposed to lowering barometric pressure (27 hPa over 8 min), the already increased number of foot lifts in response to the noxious filaments (hyperalgesia) was further increased, and foot lifts to the innocuous filament were induced (allodynia). In the CCI and SNL rats with inner ear destruction, on the other hand, lowering barometric pressure failed to augment the mechanical allodynia or hyperalgesia. These results demonstrate that barometric sensor and/or sensing system in rats is located in the inner ear. [Jpn J Physiol 55 Suppl:S226 (2005)]

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Coping strategies of humans with stress are divided into two major groups by means of stress coping inventory (SCI) after Lazarus, i.e. an emotion-focused type (E-type) and a problem-focused type (C-type). We examined whether these coping strategies and the perception of pain correlate in healthy subjects free from chronic pain. Scores for E-type (Em) and for C-type (Co) were separately counted up within an individual by SCI, and E-type tendency (ET) was calculated by an equation, ET=(Em –Co)/(Em + Co). Digital sensory branches of the radial nerve were electrically stimulated by a sequence of 16 pulses (pulse duration: 500 μsec; pulse interval 15 msec). Recognition threshold for pain and detection threshold to electrical stimulation were determined on the basis of stimulation intensity in mA. Weber's ratio in pain sensation was also registered. Regression analysis was then carried out between thresholds determined and ET. A positive correlation was found between recognition threshold to pain and ET (r²=0.319, p=0.028). Detection threshold to electrical stimulation also positively correlated with ET (r²=0.263, p=0.050). There was no correlation between Weber's ratio in pain sensation and ET (r²=0.011, p=0.704). It was concluded that individuals with a higher tendency to stress-coping strategy of E-type have higher thresholds to somatosensory stimulation. It was also shown that the sensitivity to the changes in stimulation intensity is not affected by the tendency of coping strategy. [Jpn J Physiol 55 Suppl:S226 (2005)]

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To investigate the effect of environmental enrichment on newly-born cells and migrating cells after 6-hydroxydopamine (6-OHDA) injection into the striatum (STR), male Wistar rats (P25) housed in normal or environmental-enriched cage (large cage with several equipments) for 5 weeks were injected with 6-OHDA (20μg) into the left STR and kept in each environment. Animals were received BrdU (daily, 50mg/kg, i.p.) for 3 days just before fixation at 1 or 2 weeks after 6-OHDA injection, and processed for immunostainings of BrdU and doublecortin (Dcx, a marker of migrating neuroblasts). In the subventricular zone, the number of BrdU(+) cells showed a tendency to decrease in both groups. Dcx(+) cells showed morphologies of non-migrating type (symmetric with several processes) in medial STR and migrating type (elongated and leading processes) in dorsal STR. Number of Dcx(+) cells increased in both medial and dorsal STR by 6-OHDA injection, and it was enhanced in dorsal STR of environmental-enriched group 1 week after the lesion. However, the increase of Dcx(+) cells was not seen in both environmental groups in case that 6-OHDA was injected into substantia nigra. Stronger STR damage by injection of higher dose of 6-OHDA or quinolic acid increased the number of Dcx(+) cells. Data suggest that environmental enrichment enhanced the response to increase Dcx(+) cells that was found in STR with relatively strong damage, indicating that environmental enrichment has, at least in part, effect on cell migration after brain damage. [Jpn J Physiol 55 Suppl:S226 (2005)]

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Vestibular and somatosensory systems are known as graviceptors. However, relationship between these sensors and circulatory systems has been unclear. In the study, we measured arterial pressure (AP) during 1G and microgravity condition induced by free drop. Conscious rats (n = 56) were divided into four groups, i.e., Intact, sino-aortic denervation (SAD) and vestibular lesion (VL), and SAD+VL. All groups were exposed to microgravity with and without body stabilizer (FLOAT and STAB, respectively), which is a septum in a cage to avoid body float or change in somatosensory input, without restriction during microgravity. With exposure to microgravity, AP in the FLOAT Intact rats raised 37± mmHg, compared to 1G condition, but the rise was depressed to 20± 2 mmHg in FLOAT VL rats. These changes were not seen in anesthetized rats. Moreover, the change significantly decreased in STAB rats (28 ± 3 and 7 ±5 mmHg for Intact and VL rats, respectively). No significant differences were observed between Intact and SAD rats, and between VL and SAD+VL rats. Arrhythmia, such as bigemia was observed in all FLOAT Intact rats, but the appearance rate was significantly decreased in FLOAT VL and STAB Intact rats. These results indicate that vestibular and somatosensory systems are playing important roles for controlling AP and heart rate during exposure to microgravity in conscious state. [Jpn J Physiol 55 Suppl:S226 (2005)]

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