We have shown that there are sex differences in the response of melanin-concentrating hormone (MCH) neurons to glucose using phosphorylated cyclic AMP response element-binding protein (pCREB) as a marker of neural activity. That is, glucose injection in 48 h-fasted rats decreased the number of MCH neurons expressing pCREB more promptly in females than in males. We therefore suggest that MCH neurons play a role in sex differences in feeding behavior. In the present study, we examined changes in the activity of MCH neurons under normal (free) feeding condition. Male and female rats were killed at various time point and preparations were subjected to immunohistochemical processing for the double staining of MCH and pCREB. Approximately 10% of MCH neurons expressed pCREB between meals irrespective of sex. Next, we found that approximately 40% of MCH neurons expressed pCREB 10 sec after meal initiation irrespective of sex. Five min after meal termination, on the other hand, the number of MCH neurons expressing pCREB was significantly decreased only in females but not in males. No changes in the activity of orexin, cocaine and amphetamine-related transcript, and neuropeptide Y neurons were observed. The results further suggest MCH neurons play an important role not only in sex differences in feeding behavior but also in controlling feeding behavior per se. [J Physiol Sci. 2006;56 Suppl:S220]

抄録全体を表示

The early egg fertilization process requires a change in the intracellular calcium concentration. To understand the calcium-dependent molecular mechanisms of fertilization of eggs, we isolated a 26 kDa Ca²⁺-binding protein from Xenopus eggs, a homologue of Rana Catesbeiana p26 (renamed from p26olf) isolated from the olfactory epithelium. The primary structure of Xenopus p26 shows comparatively high amino acid identity (61%) to Rana p26, and consists of two S100-like regions aligned in tandem as seen in Rana p26. By ⁴⁵Ca blot analysis and flow dialysis experiments using ⁴⁵Ca, p26 was found to bind ∼4 Ca²⁺ with an apparent Kd value of ∼9.5 μM. Genomic Southern analysis implicated that Xenopus p26 is a unique orthologue of Rana. Northern blot analysis showed that Xenopus p26 is expressed in Xenopus eggs and also in other tissues. Immunohistochemical study revealed that Xenopus p26 is localized prominently in the cytoplasm of the cortex of both the animal and the vegetal hemisphere of Xenopus eggs. Blot overlay analysis showed that several egg proteins bind to Xenopus p26 in a Ca²⁺-dependent manner, indicating the presence of target proteins of Xenopus p26. These results indicated that Xenopus p26 is a novel S100-like protein in eggs and could be involved in the early Ca²⁺-dependent event during (or after) fertilization. [J Physiol Sci. 2006;56 Suppl:S220]

抄録全体を表示

Aging is associated with a progressive decrease in appetite and food intake. Orexin-A, NPY (neuropeptide Y), and ghrelin, which are appetite-stimulating peptides, are known to play a critical role in food intake. In this study, the stimulatory effect of intracerebroventricular administration of these peptides on food intake was compared among young (4-month-old), adult (11-month-old) and old (24-27-month-old) male Wistar rats. A stainless steel cannula was implanted stereotactically into the left lateral ventricle. After a 7-day recovery period, different doses of orexin-A (0 to 3 nmol), NPY and ghrelin (0 to 1 nmol) were injected into the left lateral ventricle without anesthesia. Food consumption was measured at 1, 2, and 4 hr after injection. We also examined the plasma levels of acylated and desacyl ghrelin in young and old rats by ELISA. Intracerebroventricular administration of orexin-A and NPY stimulated food intake in young and adult rats, but, no effects were observed at any dose in old rats. Ghrelin increased food intake in a dose-dependent manner in all groups and the effect of ghrelin was reduced with advancing age. Either acylated or desacyl plasma ghrelin level did not differ between young and old rats significantly. In conclusion, the result that the orexigenic effect of these peptides, orexin-A, NPY and ghrelin were diminished in old rats could be responsible for the age-related decrease in food intake. [J Physiol Sci. 2006;56 Suppl:S220]

抄録全体を表示

The nucleus locus coeruleus (LC) and the nucleus subcoeruleus (SC) have been confirmed to be involved in descending modulation of nociceptive transmission at the spinal cord dorsal horn. We examined the age-related difference in modulating nociceptive processing at the spinal dorsal horn. Four age groups (8, 20, 50 and 70 months old) of male SD rats were used. Each group of rats was divided into the following two subgroups: LC/SC-lesioned (DC, 1 mA, 20 s) and LC/SC-intact rats. In behavioral experiments, following hindpaw inflammation (carrageenan, 2 mg, 0.1 ml), there was a significant difference in the development of hyperalgesia between the LC/SC-lesioned and the LC/SC-intact rats in young age (8 and 20 months old) but not in old age groups (50 and 70 months old). In dorsal horn neuronal activity, following hindpaw inflammation, a significant difference in both spontaneous activity and heat-evoked response was observed between the LC/SC-lesioned and the LC/SC-intact rats in young age, but not in old age. Electrical stimulation of the LC/SC significantly inhibited heat-evoked responses of dorsal horn neurons in young age, while the inhibitory effect of LC/SC stimulation was not observed when applied in old age rats. The microinjection of S-glutamate (50 nmol, 0.5 μl) into the LC/SC produced an inhibition of heat-evoked responses of dorsal horn neurons in young age but not in old age rats. These results suggest that there is an age-related difference in the function of the coeruleospinal antinociception system. [J Physiol Sci. 2006;56 Suppl:S221]

抄録全体を表示

Age-related memory impairment (AMI) is one of the most significant phenotype of brain aging and experienced by elderly people even without showing symptoms of age-related neuronal disease such as Alzheimer disease (AD). Identification of genes underlying AMI could light on the molecular mechanisms of AMI and gives clues for therapeutic strategy. However, behavioral genetic for AMI has not been much carried out because of the long lifespan of animal models. Previously, we reported that memory mutant amnesiac (amn) does not show further memory decay upon aging. Since amn encodes neural peptide supposed to control adenylyl cyclase (AC) in mushroom bodies (MBs), neuronal center for memory, we screened mutants of the genes suspected or reported to express in MBs to isolate AMI mutants. Here, we found that heterozygous DC0-PKA mutants (DC0/+) sustain robust young normal memory into old age with no effect on lifespan and its expression level upon aging. Moreover, we found that long-lived mutant does show normal AMI. These findings suggest that DC0-PKA specifically regulate AMI, and extension of longevity is neither essential nor sufficient for suppression of AMI. [J Physiol Sci. 2006;56 Suppl:S221]

抄録全体を表示

Alzheimers disease (AD), the most common form of dementia in the elderly population, is characterized by an insidious onset with memory impairment and an inexorable progression of cognitive decline. Amyloid β peptide (Aβ) is a product of sequential cleaving of amyloid precursor protein (APP) by two proteolytic enzymes, β- and γ-secretases, which cleave the APP at the N and C terminus of Aβ, respectively. The age-related activities of these secretase may induce changes in turnover of Aβ and elevate the risk of AD. From a therapeutic point of view, there is increasing interest in using β- or γ-secretase inhibitor to treat AD. In addition, neurotrophin signaling is a critical mechanism involved in synaptic plasticity, learning and memory and neuronal health. Neurotrophins can also regulate proliferation and differentiation of neural stem cells. Thus, changes in neurotrophin signaling may also be involved in age-related memory impairment and induction of AD. We examined age-related changes of mRNA expressions in these proteins. The hippocampus and cerebral cortex were dissected from young (4 weeks old), adult (50 weeks old) and aged (95 weeks old) rats and the expressions of APP, β-site APP-cleaving enzyme (BACE), presenilin 1 (γ-secretase) and neprilysin mRNA for AD-related genes and neurotrophin receptor mRNA for neural stem cell growth-related genes in these tissues were measured by Real-Time PCR. [J Physiol Sci. 2006;56 Suppl:S221]

抄録全体を表示

Neuroblastoma is one of the most common pediatric solid tumors, and is quite conspicuous. Therefore, the therapy of neuroblastma is a critical problem for health for children. Generally, cancer cells essentially require more nutrients including serum to growth as compared to normal cell. To investigate what kind of molecular event occurs in neuroblastoma cells in response to low serum stimulation could be very useful for understanding the cancer cell and the therapy. Therefore, we have performed proteomic analysis of neuroblastoma cells, GOTO in response to from 10% to 1% serum. The cells were analyzed for differential expression by fluorescence differential two-dimensional electrophoresis (DIGE) and liquid chromatography-Tandem Mass Spectrometry (LC-MS/MS). MTT assay and trypan blue exclusion assay were also performed to check growth and viability of the cells. As a result, six proteins were identified as cell signaling regulating proteins, apoptosis-related proteins or cellular stress-related proteins. The cells simulated showed decreased viability and growth at the day 1 after stimulation, but recovery of them at second day and later. Taken together, we here describe novel six proteins, which may be involved in survival and growth in neuroblastoma cells, GOTO. [J Physiol Sci. 2006;56 Suppl:S221]

抄録全体を表示

Objective: The short-range order of crystallins has been reported to be necessary for lens transparency. Developmentally, lens fiber cells continue differentiating and the rate of protein synthesis changes dramatically. Therefore, we investigated the time course of X-ray diffraction patterns and protein concentrations in developing rat lens to reach a better understanding of the required conditions to keep transparency even with high protein concentration. Methods: We obtained X-ray diffraction patterns from excised whole rat lens and measured protein concentrations at postnatal day 5 (P5), P10, and P15. The X-ray experiments were performed at 37°C. The X-ray beam (wave length: 0.1 nm) passed lens-center in a direction parallel to optic axis. Protein concentrations of lenses were measured by Bicinchonianate method, using bovine serum albumin as standard. Lens volume was obtained from weight and specific gravity. Results and Discussion: Although scattering patterns of X-ray were observed at P5 and P10, the diffraction pattern of broad ring with a characteristic spacing of around 15 nm appeared at P15. Total protein concentration of the lens fiber cell cytoplasm significantly increased especially from P10 to P15 (274.4 ± 39.6, 347.4 ± 41.6, and 569.0 ± 60.7 [mg/ml lens volume] at P5, P10, and P15, respectively, mean ± SD, each group: n = 5). Conclusion: Short-range order of crystalline developed with a marked increase of protein concentration of the lens fiber cell cytoplasm in short time. [J Physiol Sci. 2006;56 Suppl:S222]

抄録全体を表示

Neuronal positioning is thought to be crucial for cerebral development, but little is known about the underlying regulatory mechanisms. We generated mice lacking the RP58 gene encoding a transcriptional repressor. In vivo labeling with BrdU revealed that presumptive subplate neurons are diffusely distributed in all cortical layers and that neuronal migration represents a reeler-like outside-in pattern in the mutant mice. In this study, we performed molecular marke analysis using Tbr-1, ER81 and mSorLA probes. In the RP58 deficient mice, ER81 positive layer V neurons, which were normally laminated above Tbr-1 positive layer VI neurons, were found beneath Tbr-1 positive cells. These results confirm the outside-in pattern of the mutant cortex. The mSorLA positive layer II-III neurons were not detected in the mutant mice. The result suggests that RP58 is essential for the differentiation of layer II-III neurons. [J Physiol Sci. 2006;56 Suppl:S222]

抄録全体を表示

The migration of immature neurons constitutes one of the major processes by which the central nervous system takes shape. Completing the migration at the final destination requires the loss of cell body motility, but little is known about the signaling mechanisms underlying this process. Here we show that a loss of transient Ca²⁺ elevations triggers the completion of cerebellar granule cell migration. Simultaneous observation of the intracellular Ca²⁺ levels and cell movement in cerebellar slices of the early postnatal mice revealed that granule cells exhibit distinct frequencies of the transient Ca²⁺ elevations as they migrate in different cortical layers, and complete the migration only after the loss of Ca²⁺ elevations. The reduction of the Ca²⁺ elevation frequency by decreasing Ca²⁺ influx, or by inhibiting the activity of PLC, PKC, or Ca²⁺/calmodulin, halted the granule cell movement prematurely. In contrast, increasing the Ca²⁺ elevation frequency by increasing Ca²⁺ release from internal stores, or by elevating intracellular cAMP levels, significantly delayed the completion of granule cell migration. The timing of the loss of Ca²⁺ elevations was intrinsically set in the granule cells and influenced by external cues. These results suggest that Ca²⁺ signaling, dictated by multiple signaling systems, functions as a mediator for completing the migration of immature neurons. [J Physiol Sci. 2006;56 Suppl:S222]

抄録全体を表示

Domoic acid (DA) is the structural analogs of Kainic acid (KA) belongs to a group of amino acid analogues called excitotoxins. DA is shown to be about 10 times more toxic than KA. In rodents, DA produces extensive neuronal damage in the hippocampal pyramidal neurons and behavioral effects ranging from inactivity to seizures and distinguishable by its unique ability to elicit a scratching response. In the case of intraperitoneal DA administration, neuronal damage was observed in a wide range. In this study we examined the neuronal damage after intraperitoneal DA administration and cell proliferation in the adult rat whole brain. The most extensive neuronal cell damage was observed in CA3 subfield as evaluated by HE staining. While many TUNEL positive cells were observed in the granular cell layer of cerebellum. The process of neuronal cell death was made up mingled necrosis and apoptosis. TUNEL histochemistry revealed a time dependent sequential apoptotic cell death after DA administration. During the first 2 days postinjection, apoptosis in the cerebellum was only evident in the brain. At 3 days, the entire hippocampus and cortex become apoptotic. The distribution of the BrdU positive cells were most abundant in the dentate gyrus and not correlated to the degree of the neuronal damage. [J Physiol Sci. 2006;56 Suppl:S222]

抄録全体を表示

It is known that role of GABA_A-R mediated actions is important for early CNS development. The radially migrating cells derived from the ventricular zone (VZ) may affected by the actions. GABA content in the brain of GAD67-GFP knock-in mouse decrease compared with the wild type mice. Therefore, in this study, we investigate the influence of the circumferential GABA concentration to radially migrating cells by using GAD67-GFP knock-in mice. Furthermore, as it was known that GABA_A-R is affected by taurine, the influence of taurine to radially migrating cells was also investigated.The radially migrating cells were labeled by means of in utero electroporation at E14. Three days after the electroporation, labeled cells located in CP, intermediate zone, and VZ were counted. There was no significant difference in distribution among genotypes of GAD67-GFP knock-in mice. GABA_A-R mediated currents were recorded by whole-cell recording from labeled cells. Evoked GABA current had dose-dependent manner and had no differences among genotypes. These results suggest that the cells generated in the VZ possess rather equivalent GABA_A-Rs and migrate radially independent of circumferential GABA concentration. Therefore, we have examined the influence of circumferential taurine to GABA_A-R mediate actions in vivo by using taurine metabolism blocker, D-cystein sulfinate. [J Physiol Sci. 2006;56 Suppl:S223]

抄録全体を表示

Galectins constitute a family of lectins that bind to β-galactoside and are present in a wide range of animal species. Although galectin-1 has been recently shown to promote axonal elongation in the PNS, it is unclear whether galectin-1 implicates in the CNS regeneration. Unlike the mammals, the fish optic nerve can regenerate their axons after transection, so we studied effects of galectin-1 on axonal regeneration after fish optic nerve transection. We isolated a cDNA fragment for goldfish galectin-1 with probes of PCR products amplified by a primer constructed from zebrafish sequence. We got a band of 396bp from goldfish retina. Since nucleotide sequence of this band was 98% homology to that of zebrafish galectin-1, we detected the transcripts of galectin-1 in the goldfish retina. Using this cDNA probe, in situ hybridization was performed in the goldfish retina following optic nerve injury. The level of the mRNA increased at 3days, and peaked at 10-20days, and then returned to the control level by 30days after nerve injury. The increase of the mRNA was located strongly in the ganglion cell layer, and weakly in the inner nuclear layer and outer nuclear layer. The levels of galectin-1 protein showed a similar expression pattern to that of the mRNA. The period of increased levels of galectin-1 mRNA and protein correlated well to the period when ganglion cells start to regrow their axons after lesion. So, we are now in progress to evaluate the effect of galectin-1 on neurite outgrowth in retinal explant culture. [J Physiol Sci. 2006;56 Suppl:S223]

抄録全体を表示

Fish optic nerve can regenerate after nerve transection. In this study, to evaluate the regeneration of visual function after nerve injury, we quantified the optokinetic and chasing behaviors of moving zebrafish with optic nerve transection by a computer image processing system. In an optokinetic movement, zebrafish can follow the rolling drum with black-and-white vertical stripes. In a chasing movement, one fish can chase the other. The optic nerve injury induced a complete loss of their movements in zebrafish. The recovery of optokinetic behavior in adult zebrafish was 25 days after nerve injury, whereas the recovery of chasing behavior in adult two zebrafish was 80-100 days after nerve injury. In the development, young zebrafish can gain the optokinetic and chasing behavior by 15 days and 60 days after hatching, respectively. Furthermore, we cloned some interesting genes upregulated in the retina during optic nerve regeneration. Purpurin and GAP-43 were very different in their expression pattern of the upregulated period. The expression of purpurin was very transient for less than 10 days, whereas that of GAP-43 was sustained for more than 100 days after optic nerve injury. Now, we compare their expression pattern in the developing zebrafish retina. Such a comparative study of molecular and behavioral phenotypes during development and regeneration might be useful for understanding molecular structure of zebrafish visual system. [J Physiol Sci. 2006;56 Suppl:S223]

抄録全体を表示

Our previous study demonstrated that zinc deficient (ZnX) rats fed zinc deficient diet during 4 weeks enhanced sodium preference (Futani et al., 2005). In the present study, we conducted behavioral experiment to investigate whether feeding period of zinc deficient diet affect this sodium preference or not. As the zinc deficient animals, male Wistar rats fed the zinc deficient diet during 1 week after the weaning were used. Results were as follows; (1) In the long-term (48 h) two-bottle preference test, the preference percents for 0.1 and 0.3M NaCl in some ZnX rats were higher than those in the control rats. (2) In the short-term (10 min) test, there was no significant difference in the preference percents between ZnX and control rats. These results suggest that 1 week is enough period for some rats to occur high sodium preference and taste may not play a role for enhancement of this sodium preference. [J Physiol Sci. 2006;56 Suppl:S224]

抄録全体を表示

Zinc is known to be an essential trace element for all organisms. In human subjects body growth and development is reported to be strictly dependent on zinc. The nervous, reproductive and immune systems are also particularly influenced by zinc deficiency. However, the effects of zinc deficiency on the number of immuno-responsible cells have not yet been fully elucidated. Therefore, we studied the effects of zinc deficiency on the number of white blood cells in rats. Four weeks old male Sprague Dawley rats were used, and randomly divided into the control diet group (CON: Zn=53.5mg/kg diet) and zinc deficient diet group (ZDD: Zn=1.9mg/kg diet) . Both group rats were fed in each diet for 26 days. During the experimental period, the numbers of white blood cells, neutrophils, eosinophils, basophils, lymphocytes and monocytes were analyzed with a flow-cytometer. The number of neutrophils in the ZDD in 18th to 26th days was significantly higher than those of the CON group. The numbers of eosinophils and basophils of the ZDD in 14th day were 2.0 and 5.2 times significantly higher, respectively, than those of the CON. The numbers of lymphocytes in the ZDD in 18th to 26th days were significantly lower than those of the CON. However, The numbers of total white blood cells and monocytes were not changed in both groups. These results suggest that zinc deficiency increases the number of natural immunity cells and decreases the number of acquired immunity cells in rats. [J Physiol Sci. 2006;56 Suppl:S224]

抄録全体を表示

Zinc has been shown to regulate the growth, acid-base equilibrium and oxygen transport functions. Zinc is also known to play an important role in red blood cell formation, which is related to the physiochemical properties of red blood cells (RBC), hematopoietic differentiation factors and hematopoietic hormones. However, the effects of zinc deficiency on the number and volume of RBC and hemoglobin levels are still unknown. Therefore, we examined zinc deficiency-induced changes of the number and volume of RBC and hemoglobin concentration in rats. Four weeks old male Sprague Dawley rats were divided into zinc deficient diet group (ZDD: zinc=1.9mg/kg diet) and the control group (CON: zinc=53.5mg/kg diet), and both group rats were fed for 26 days. During the experimental period, the number and volume of RBC and hemoglobin concentration in rats were analyzed by a flow-cytometer. Mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) in the ZDD were significantly lower than those in the CON. The number of RBC and mean corpuscular hemoglobin concentration (MCHC) in the ZDD were significantly higher than those in the CON. The peak of distribution of RBC in the ZDD was shifted to small size and the distribution width was significantly reduced, as compared with those in the CON. These results suggest that zinc deficiency in rats clearly induces the increase of RBC numbers, and the reduction and homogeneity in the volume of RBC. [J Physiol Sci. 2006;56 Suppl:S224]

抄録全体を表示

Zinc is an essential cofactor for many enzymes, including those that regulate the metabolism of vitamin A and ethanol in the liver. Alcohol dehydrogenase (ADH) is also a metalloenzyme in which zinc acts as a prosthetic group and a stabilizer of the quarternary protein structure. However, the effects of zinc deficiency diet (ZDD) on liver cytosolic ADH activity and the recovery effects from ZDD have not yet been fully elucidated. Therefore, we studied the effect of ZDD and the recovery effects on the liver ADH activity in rats. Four weeks old male Sprague Dawley rats (n=32) were divided into four groups : (a) ZDD (zinc=1.9mg/kg diet) for 26 days, (b) the control group (zinc=53.5mg/kg diet) for 26 days, (c) ZDD diet (zinc=1.9mg/kg diet) for 26 days and then replaced on the zinc supplemented control (zinc=53.5mg/kg diet) for 19 days, and (d) the control group for (c). Liver cytosolic ADH activities were assayed spectrophotometrically at 38°C, and liver cytosolic protein assays were performed by the method of Lowry et al. Liver cytosolic specific ADH activities were significantly reduced to about 1/4, by ZDD for 26 days. However, a significant reduction in the activity of liver cytosolic ADH was recovered to the control levels when zinc intake (zinc=53.5mg/kg diet) of the normal levels was supplemented for consequtive 19 days to the ZDD in rats. These results suggest that liver cytosolic ADH activity in rats regulated by the magnitude of zinc intake. [J Physiol Sci. 2006;56 Suppl:S225]

抄録全体を表示

Previous studies have demonstrated that zinc deficient rats drink 0.3M NaCl, avoided by normal animals, in preference to water. We investigated the participation of humoral factors in such salt intakes in zinc deficient rats by analyzing serum concentrations of aldosterone, angiotensin II and sodium. Animals were fed a zinc deficient diet (group 1) or the normal control diet (groups 2 and 3) ad libitum. Group 3 was pair fed with group 1. Serum constituents and preference for NaCl solutions (48-hr two-bottle choice test) were determined at one and four weeks after the onset of feeding. The intake of 0.3M NaCl solution in preference to water occurs in group 1, but not in groups 2 and 3, from one week after the onset of feeding. There was no significant difference in serum concentrations of sodium among all groups throughout experiments. However, estimates of group 1 tended to be lower than those of other two groups four weeks after the onset of feeding. Angiotensin II concentrations decreased significantly in group 1 compared with in two other groups, whereas aldosterone concentrations in group 1 were approximately two times as high as those of two other groups. These results suggest that in zinc deficient animals with low serum concentrations of sodium, aldosterone is upregulated through synthetic pathways different from rennin-angiotensin system. Increased central action of aldosterone may lead to increased sodium appetite. [J Physiol Sci. 2006;56 Suppl:S225]

抄録全体を表示

The neonatal hypoxic-ischemic encephalopathy (HIE) rat model, in which one of carotid arteries ligation followed by hypoxic insult, has been already established. However, differences of effects in the left and right carotid arteries ligations have not been yet clarified by behavioral study. In this study, we examined differences in the effects of left and right carotid arteries ligation on this HIE model by behavioral study. We ligated the left (L-group, n=12) and the right (R-group, n=8) carotid arteries of 7-day-old rats under inspired isoflurane anesthesia, then exposed the rats to 8% oxygen for 15 min at 37 degree, then returned the animals to their mothers. A sham operation group (S-group, n=7) was also prepared. Swimming direction test was performed between 3 and 6 weeks later. Each rat was put in the center of a circular pool (diameter, 150cm; water depth, 15cm). We assessed the rat's swimming direction (clockwise or counterclockwise) when the rat arrived at the pool wall on ten trials per day on different days. The L-group and R-group swam clockwise and counterclockwise respectively, significantly more frequent compared with the S-group. These findings imply that the effects of HIE insult may be easily assessed by a simple swimming direction test. [J Physiol Sci. 2006;56 Suppl:S225]

抄録全体を表示

Free radicals/reactive oxygen species (ROS) are related to various disorders including inflammation, aging, and cancer. However, living systems have essential antioxidant mechanisms by which these harmful radicals can be scavenged, i.e., free radical-scavenging activity (FRSA). In the present study, we examined how salivary FRSA is affected by physical and mental activities, which included 1) ingestion of green tea or coffee, 2) a swimming or dancing lesson, 3) watching a comic video or stimulation by lavender or isovaleric acid odors, and 4) smoking. The FRSA was determined by using the DPPH (1,1'-diphenyl-diphenyl-2-picrylhydrazyl) method. In the study on the individual activities, beverage ingestion increased FRSA, whereas exercise decreased it. Watching an amusing video program or stimulation by a pleasant aroma increased FRSA. In contrast, an unpleasant odor had no effect on FRSA. The FRSA decreased immediately after smoking, but thereafter increased after. Thus salivary FRSA was affected by not only physical activities, but also mental activities. The FRSA in saliva may be a parameter for reflecting the health status of individuals. [J Physiol Sci. 2006;56 Suppl:S225]

抄録全体を表示

We recently found that arial natriuretic peptide (ANP) inside and outside the blood-brain barrier inhibits the lipopolysaccharide (LPS)-induced fever in rats in vivo. Since ANP inhibits LPS-induced activation of transcription factors and subsequent production of pyrogenic cytokines in macrophages in vitro, it is possible that brain ANP inhibits the activities of the cytokine-producing brain macrophages, microglias, as well. In the present study, we used the primary culture of microglia to investigate whether ANP inhibit LPS-induced microglial activations through its effect on the activation of proinflammatory transcription factors, NF-κB and AP-1. We examined the production of interleukin-1β and nitric oxide and morphological changes of microglia for its activation. We have gotten interesting results, which we will report in the forthcoming "Meeting of the Physiological Society of Japan". [J Physiol Sci. 2006;56 Suppl:S226]

抄録全体を表示

Propolis, one of the oldest medicines, attracts much attention from the medical community, because of its antibiotic and anti-tumor activities. There are accumulating evidences indicating that propolis ingredients such as caffeic acid phenyl ethyl ester (CAPE) and quercetin (QU) have a variety of novel action including neuroprotective action in addition to well-known anti-tumor activities. It is of significance for the propolis study to elucidate molecular mechanisms underlying these novel actions of propolis. Propolis itself, however, cannot be used in in-vitro experiments that utilize cultured tissues because of its poor solubility in water. To circumvent this problem, we have carried out an in-vitro study of anti-tumor action of Brazilian propolis using water-dispersible form of propolis (WDP). Using rat C6 glioma cells, we have demonstrated a dose-dependent anti-tumor action of WDP. The effects of WDP are compared with those of active ingredients of propolis. Both QU and CAPE were found to inhibit cell-growth of C6 cells in serum-supplemented DMEM. However, QU failed to induce C6 cell death after serum-deprivation, while both WDP and CAPE killed C6 cells. Thus, the inhibition of C6 growth induced by WDP could be accounted on the basis of cytotoxic action of CAPE. QU does not kill C6 cells, but inhibits cell proliferation. [J Physiol Sci. 2006;56 Suppl:S226]

抄録全体を表示

Metabolic syndrome is more prevalent in men than in women. However, postmenopausal women became to have its higher incidence. We investigated whether insulin sensitivity is deteriorated in ovariectomized rats, and is improved by chronic estrogen replacement. Female Wistar rats aged 9 weeks were ovariectomized. After 4 weeks, the rats were assigned either to a placebo-treated (P) group (n=8) or a group treated with 17β-estradiol (E2) (n=8), subcutaneously implanted with either placebo- or 17β-estradiol (1.5 mg / 60-day release) pellets. After 4 weeks of estrogen or placebo treatment, the body weight, percent body fat and wet weights of visceral fat were increased in the P compared with the E2 group, while cumulative food intake per body weight was enhanced in the E2 group. During a 1 g/kg intravenous glucose tolerance test, the glucose and insulin responses (incremental areas under the curve) were greater in the P group than the E2 group. Plasma concentration of free fatty acid was marginally lower, and triglyceride was significantly lower in the P group than the E2 group. Plasma levels of leptin and TNF-α were not different between the two groups, but adiponectin was higher in the P group than the E2 group. These results suggest estrogen deficiency increases visceral fat mass, and deteriorates insulin sensitivity. [J Physiol Sci. 2006;56 Suppl:S226]

抄録全体を表示

It has been suggested that central serotonin is anorexigenic and this action is mediated, at least in part, by 5-HT2A/C receptors and activation of POMC neurons. This study examined the systemic effects of 5-HT2A/C receptor agonist on food intake, body weight and blood glucose levels in Zucker fatty rats in which leptin receptor is impaired. Fatty rats were intraperitoneally (i.p.) administered with a 5-HT2A/C agonist DOI at 1.0 mg/kg (n=4) or saline (n=4) from 7 to 10 weeks of age, and food intake, body weight and blood glucose levels were measured. Control Lean rats received the same treatment. In long term measurements, daily food intake and weight gain in Fatty rats were significantly decreased in DOI group as compared to control group. In Lean rats, neither food intake nor weight gain was significantly different between DOI and control groups. There were no difference in blood glucose levels between DOI and control groups both in Fatty and Lean rats. In Fatty rats, upon termination of i.p. DOI food intake was temporarily increased, however weight did not change significantly, indicative of increased energy consumption. In short term measurements, food intake was reduced at 1-2.5 hrs after i.p. DOI in Fatty but not Lean rats, and blood glucose level was lowered at 0.5-3 hrs both in Fatty and Lean rats. These results indicate that activation of 5-HT2A/C restricts feeding and ameliorates obesity in Fatty rats and that some of these effects may be produced by restoring the downstream signaling pathway of the leptin receptor impaired in Fatty rats. [J Physiol Sci. 2006;56 Suppl:S226]

抄録全体を表示

Heat shock proteins (HSP) are synthesized by cells of all organism resistance to internal and external cellular stresses including physical stress, metabolic stress, and disease. Exercise is a sufficient stimulus to induce and enhance the synthesis of HSP70 and prolonged endurance exercise also causes an inflammatory reaction. Exercise induced a transient elevation in circulating leukocytes, driven largely by a granulocytosis but also influenced by an increase monocytes and lymphocytes. Present study was designed to investigate the expression of HSP70 in human peripheral blood leukocytes after acute moderate intensity exercise in trained runners and untrained subjects. Ten male long distance runners (TR, n=10, 21.3 yrs) and untrained control subjects (UT, n=10, 22.4 yrs) participated in this study. Subjects ran on a treadmill for 1 hr at 70% of heart rate reserve (HRR). Blood were taken immediately before and immediately after exercise, and at 30 minutes after exercise. HSP protein was evaluated by immunoblotting. Baseline HSP70 protein levels in TR was significantly lower than that in UT. Although expression rate of exercise induced HSP70 in both groups were similar, but UT showed significant higher HSP70 levels versus TR after exercise and at 30 minutes after exercise. We conclude that 1 hr treadmill running at 70% HRR intensity (moderate to heavy) is a sufficient stimulus of leukocytosis, neutrocytosis, lymphocytosis, and HSP70 expression in leukocytes. Adaptation to training are observed in TR subjects [J Physiol Sci. 2006;56 Suppl:S227]

抄録全体を表示

We investigated effect of fluid intake on thermal and cardiovascular responses during 1-h recovery after exercise. Six subjects (five untrained males and one female) cycled (at 60%VO_2max) for 60 min in hot-humidity conditions to produce dehydration of 1-2.5% body weight. During the recovery at thermoneutral(at 28°C with rh 40%), the subjects underwent two trials of no fluid (C) and ingested water (F) of 500 ml (containing electrolytes and carbohydrates) after the exercise.We continuously measured weight loss as index of insensible perspiration, tympanic (T_ty), rectal (T_re), and skin (T_sk) temperatures, skin blood flow (SkBF), heart rate (HR, included R-R interval), systolic (SBP) and diastolic (DBP) blood pressures, palm sweat rate (SR). Mean arterial pressure (MAP) was calculated as (SBP+2×DBP)/3. Rate-pressure product (RPP) and cutaneous vascular conductance (CVC) calculated HR×SBP and SkBF divided by MAP, respectively. CVC, MAP, SkBF, T_re and mean T_sk were not significantly different between the tests. Insensible perspiration and R-R interval were significantly increased by fluid intake at the early stage. Palm SR and RPP in the F were significantly lowered at the early stage, and stable trend during the recovery, as compared with the C. T_ty also decreased in comparison with the C at the initiation of the recovery. The present results suggest that fluid ingestion is reduce thermal and cardiovascular strains after exercise-induced thermal dehydration, and may be to alleviate the autonomic regulatory responses during rehydration in humans. [J Physiol Sci. 2006;56 Suppl:S227]

抄録全体を表示

Recent instruments for the study of thermoregulation in rodents are usually large and often require troublesome trainings of animals. In this study, we designed, made and tested a new simple instrument for investigating rodents' behavioral thermoregulation. The apparatus was composed of two stainless-steel hollow plates (plate A and plate B) with a length of 20cm and width of 5cm. Each plate had an inlet and an outlet that were connected to a separate constant-temperature bath (bath 1 and bath 2). The water temperatures of the baths were controlled at one designated temperature within 10 and 45 degrees and pumped into the plates. A change switch for the water supply was inserted between both the plates and the baths. In the normal switch position, bath 1 supplied water plate A, and bath 2 supplied water plate 2, and in the reverse position, vice versa. Plates A and B were arranged and covered with a surrounding transparent fence 20cm high in a climatic chamber. A rodent stayed inside the fence and moved on plate A or plate B. The position of the rodent was observed by a video camera. We tested thermoregulatory behavior of eight male mice using this instrument. By shuffling the plate temperatures between 10 and 45 degree, the mice moved to the plates with a temperature close to the 35 degree. The findings implied our instrument might be useful as an apparatus for the study of behavioral thermoregulation. [J Physiol Sci. 2006;56 Suppl:S227]

抄録全体を表示

Effects of therapeutic hypothermia soon after hypoxic-ischemic (HI) insults in infants is now receiving attention in perinatology. Although the neonatal HI rat model is established in the experimental study, effects of therapeutic hypothermia in rats' actual motor activity has rarely been tested. In this study, we investigated the effects of therapeutic hypothermia in motor function of HI neonatal rat model using rotor rod test. We ligated the left common carotid artery in ten seven-day-old rats under inspired isoflurane anesthesia, then exposed the rats to 8% oxygen at 40 degrees for 15 min. Therapeutic hypothermia was induced in 5 of the rats (hypothermia group) immediately after the insult by maintaining the rats' body temperature at 30 degrees for 12 hrs. In the other the rats' body temperature was maintained around 36 degrees (normothermia group). Rotor rod test was performed two months after the HIE insults. On the 1st day of experiments, all rats fell from the rod rotating at 5 rpm within 60 sec. On the 2nd day, all rats in the hypothermia group stayed on the rotating rod for 60 sec, although all rats in the normothermia group again fell within 60 sec. On the 3rd day, all the rats stayed on the rod at 7 rpm for 60 sec. Hypothermia soon after HI insult may improve motor function compared to normothermia. [J Physiol Sci. 2006;56 Suppl:S227]

抄録全体を表示

Natriuretic peptide (NP) such as atrial NP (ANP), brain NP (BNP) or C-type NP (CNP) is a bioactive hormone well known to induce a decrease in blood-pressure, and natriuresis. By contrast, angiotensin II (ANG II), an another bioactive peptide, has the opposite effects such as an increase in blood pressure and a retention of sodium within the body. In other words, NP and ANG II participate in the blood pressure and body fluid regulation through the physiological mechanisms conflicting with each other. Recently, we have found that ANG II and its type 1 receptor are involved in the bacterial endotoxin (lipopolysaccharide; LPS)-induced fever. Since NP reportedly contributes to the inhibition of the inflammation, it is likely that NP has an opposite (inhibitory) effect on the fever to that of ANG II. We examined this possibility and have gotten interesting results, which we will report in the forthcoming "Meeting of the Physiological Society of Japan". [J Physiol Sci. 2006;56 Suppl:S228]

抄録全体を表示

Prostaglandin E₂ (PGE₂), the brain mediator of fever, is produced in brain endothelial cells through the actions of PGE₂-synthesizing enzymes including cyclooxygenase-2 (COX-2) and microsomal-type PGE synthase (mPGES). However, the type of phospholipase A₂ (PLA₂) working in the upstream of COX-2 is unknown. We have previously shown a possible involvement of calcium-independent PLA₂ (iPLA₂) in brain PGE₂ production during lipopolysaccharide (LPS)-induced fever, since systemic pretreatment of rats with an inhibitor of iPLA₂, BEL, suppressed fever and brain PGE₂ production. Here, we examined whether BEL directly acts on brain endothelial cells to suppress PGE₂ production using an ex vivo preparation of brain blood vessels. PGE₂ release from subarachnoidal blood vessels, which were isolated from LPS-injected rats and incubated ex vivo, was suppressed by BEL (10μM) added to the incubation medium. Unexpectedly, BEL also suppressed COX-2 expression in endothelial cells of isolated blood vessels. These results indicate that BEL directly acts on brain endothelial cells to suppress PGE₂ production, and suggest that arachidonic acid produced through the BEL-sensitive pathway might not only be a substrate for COX-2 but also be involved in the induction of COX-2. Our findings support the idea that iPLA₂ is working in the upstream of COX-2 in brain endothelial cells to produce PGE₂ during LPS-induced fever. [J Physiol Sci. 2006;56 Suppl:S228]

抄録全体を表示

The effect of thiol-reductant α-lipoic acid on diurnal temperature (Tc) changes and fever was assessed in pigeons (Columba livia) in ambient temperature of 26 ± 1°C, with lights on at 09:00 and off at 21:00. Intravenous (iv) injection of 10 μg/kg E. coli lipopolysaccharide (LPS) at 13:00 evoked after latency of 30 min first a variable decrease of Tc, followed by an increase starting 90 min later towards values which were 0.78 ± 0.04°C higher than control between 18:00 and 20:00. Tc decreased in the dark phase parallel to the decline of Tc of afebrile pigeons but with a flatter slope. Iv injections of 12.5, 25.0 and 37.5 mg/kg α-lipoic acid at 16:00 lowered Tc dose-dependently by 0.75 ± 0.09°C, 1.47 ± 0.14°C, and 1.90 ± 0.18°C, respectively, the hypothermic effects lasting 50, 90 or 140 min, respectively. Treatment with the non-competitive glutamate N-methyl-D-aspartate (NMDA) receptor antagonist dizocilpine maleate (MK801) blocked the α-lipoic acid-induced hypothermia. Injection of 25 mg/kg α-lipoic acid 3 h after LPS caused a decrease of Tc by 1.05 ± 0.20°C, lasting about 60 min. Tc then returned to level not significantly different from the afebrile state between 18:00 and 20:00. The hypothermic action of α-lipoic acid is assumed to be induced by reduction of vicinal thiol groups of the NMDA receptor, because the hypothermic effect is blocked by NMDA receptor antagonist MK801. The data support the hypothesis that the NMDA receptor is involved in thermoregulation of birds and that augmented oxidation of vicinal thiol groups attached to its ion channel leads to hyperthermia or causes fever. [J Physiol Sci. 2006;56 Suppl:S228]

抄録全体を表示

Exogenous aFGF given via the icv route activates the sympathetic outflow innervating interscapular brawn adipose tissue and adrenal medulla. We investigated the effect of exogenous aFGF given via the iv route on body temperature in rats (Wistar strain) under urethane-chloralose anesthesia using thermistor thermometer or in free moving animals using telemetry system. When animals were given aFGF (100 ng/kg) 30 min before the onset of dark period, nocturnal core temperature (Tc) elevated for 9 h after the aFGF challenge. Peak in Tc induced by aFGF was about 1.5 °C (39.6±0.2) higher than that (38.5±0.1) in animals given saline. Records of tail temperature in rats given aFGF showed three phasic thermal responses (two peaks followed by a trough). The aFGF-induced hyperthermia significantly reduced by a resection of the vagal hepatic branch and abolished completely by the combined hepatic vagotomy with bilateral gastric vagotomy. Furthermore, pretreatment with 30 mg/kg methylpredonisone, artificial glucocorticoid, given intraperitoneally significantly attenuated the aFGF-induced hyperthermia. These data suggest 1) that exogenous aFGF given via the iv route induces fever, and 2) that afferent signals from the hepatic and gastric vagus nerves play an important role in the aFGF -induced fever, 3) that aFGF-induced fever might be triggered by glococorticoid-sensitive inflammation processes within gastrointestinal regions. [J Physiol Sci. 2006;56 Suppl:S228]

抄録全体を表示

We investigated the effects of alcohol on thermoregulatory responses and thermal sensations during cold exposure in humans. Eight healthy men participated in this study. Experiments were conducted twice for each subject at a room temperature of 18 °C. After a 30-min resting period, the subject drank either 15% alcohol (alcohol session) at a dose of 0.36 g/kg body weight or an equal volume of water (control session). Deep body temperature gradually decreased throughout 90-min measurement both in the alcohol and control sessions (from 36.9 ± 0.1 °C to 36.6 ± 0.1 °C) without any statistically significant differences. Metabolic rate in the control session started to increase 30 min after the onset of measurement. On the other hand, in the alcohol session, metabolic rate remained unchanged in spite of a decrease in body core temperature. Whole body cold sensation became strong in the control session during cold exposure, whereas it changed to "not cold at all" after alcohol drinking, which would inhibit the behavioral regulation, if available. In the previous study we have already shown that both autonomic and behavioral thermoregulation is also modulated to decrease body temperature in hot environment (Yoda et al., 2005). Thus, alcohol influences all thermoregulatory mechanisms including behavior so as to decrease body core temperature. These results suggest that alcohol affects some elements common to all the effector mechanisms, most presumably thermosensitive neurons in the brain. [J Physiol Sci. 2006;56 Suppl:S229]

抄録全体を表示

It is known that stress-induced hyperthermia is attenuated by intraperitoneal administration of antipyretic drugs. To investigate the site of action of antipyretic drugs on stress-induced hyperthermia and motor activity, adult male rats were subjected to cage switch stress or 30-min immobilization and administrated intra-preoptic/anterior hypothalamic (PO/AH) or intraperitoneal antipyretic drugs. The intraperitoneal administration of sodium salicylate significantly attenuated the hyperthermia induced by cage switch compared with saline group, but the intra-PO/AH administration of sodium salicylate did not attenuate the hyperthermia induced by cage switch compared with saline group. The intraperitoneal administration of acetaminophen slightly attenuated the hyperthermia induced by cage switch compared with saline group, but there was no significant difference. When rats were subjected to 30-min immobilization, stress-induced hyperthermia was significantly attenuated by intraperitoneal administration of sodium salicylate compared with saline group. Furthermore, the intraperitoneal administration of sodium salicylate induced hypothermia during several hours. These data suggest that stress-induced hyperthermia is not mediated by central nervous system and the stronger stressor may induce the production of prostaglandin during several hours. [J Physiol Sci. 2006;56 Suppl:S229]

抄録全体を表示

Previously we and others reported enhanced sweat rate (SR) during passive cycling (PC) after moderate exercise. This response may have occurred due to a combination of accumulated metabolites coupled with mechanoreceptor stimulation. To test whether accumulated metabolites associated with dynamic exercise contribute to this response, 6 healthy males performed 15-minute bouts of supine right leg exercise on a tandem cycle ergometer (1.5 kpm at 50 rpm). Following this exercise bout, subjects performed one of the following conditions for 5 minutes per condition; 1) stopped exercise (NC), 2) PC of the exercised leg (PR), and 3) PC of the non-exercised leg (PL). These protocols were randomly assigned with at least 30 min rest between bouts. PC was accomplished via a second person cycling the tandem ergometer, which allows for mechanical stimulation of the muscle with minimal activation of central command. One-leg exercise increased heart rate, mean arterial pressure (MAP), esophageal temperature and SR. At the end of exercise there were no significant differences in these parameters among the exercise bouts. SR was greater during both PR and PL bouts relative to NC bout, although no significant difference was observed between PR and PL conditions. These results suggested that accumulated metabolites in the active muscle are unlikely to contribute to the enhanced sweating during mechanical stimulation following moderate exercise. [J Physiol Sci. 2006;56 Suppl:S229]

抄録全体を表示

We have demonstrated that the TGF-beta in the cerebrospinal fluid (CSF) was activated by poly I:C injection (i.p.) and the neutralization of TGF-beta with antibody partially suppressed the poly I:C-induced fever. We will now need to examine whether central TGF-beta itself induces fever. 2 hours after injection of TGF-beta into the cisterna magna of rat, significant elevation of core body temperature was observed. To elucidate the mechanism of TGF-beta-induced fever in detail, we examined the concentration of prostaglandin E2 (PGE2), the mediator of fever, in the CSF and the expression of cyclooxygenase-2 (COX-2), the enzyme producing PGE2, in the rat brain 5 hours after TGF-beta injection. The significant increase of PGE2 in the CSF and the induction of COX-2 in the endothelial cells in the rat brain were observed. Moreover, pretreatment with Nimesulide, a selective inhibitor of COX-2, significantly suppressed the elevation of core temperature induced by TGF-beta administration. These results suggest that central TGF-beta activated by poly I:C injection elevates core temperature through the COX-2–PGE2 pathway in brain. [J Physiol Sci. 2006;56 Suppl:S229]

抄録全体を表示

Previously, we have demonstrated that transforming growth factor-beta (TGF-beta) was activated in the brain and related to the central fatigue and energy metabolism during exercise. Infection of virus or bacteria elevates various kind of cytokine in the brain, and it has been known that some cytokines mediate sickness behavior including decreased food intake, lowered spontaneous motor activity, and fever. Similar symptoms are often observed after exercise. Then, we postulated that TGF-beta might also be activated in the brain and be associated with various physiological changes during infection. In the present study, we examined the relation between TGF-beta and physiological changes caused by viral infection. Intraperitoneal administration of double stranded synthetic RNA (Polyinosinic: polysytidylic acid: Poly I:C) was used as an experimental model of viral infection. When spontaneous motor activity began to decrease by Poly I:C, activated form of TGF-beta increased in cerebrospinal fluid. We next examined the role of TGF-beta activated by Poly I:C administration. Poly I:C-induced fever was partially inhibited by neutralization of TGF-beta using anti-TGF-beta neutralizing antibody. However anti TGF-beta antibody was not able to inhibit the decrease in spontaneous motor activity. These results indicated that in the brain TGF-beta, known to anti-inflammatory cytokine, might act as pro-inflammatory cytokine during infection. [J Physiol Sci. 2006;56 Suppl:S230]

抄録全体を表示

We have shown that when rats and humans were subjected to daily heat exposure limited to several hours at a fixed time of day and then transferred to a constant thermoneutral ambient temperature, the pattern of nycthemeral variations in their core temperature (T_cor) was altered so that T_cor fell for 3–4 hours during the period when they had previously been exposed to heat. In addition, heat acclimation-induced changes in thermoregulatory functions, e.g. enhancements of thermoregulatory responses to acute heat load, were clearly seen during the period of the previous heat exposure time. It has been well known that cutaneous blood flow has a crucial role in maintaining heat loss especially in hot environment. In this study, therefore, we examined effects of heat acclimation on function of the aorta and tail arteries and also investigated how repeated timed daily heat exposures affect the daily cycle of their function in rats. Wister rats were subjected to heat (33°C) only during the second half of the dark period for 10 consecutive days. After the heat exposure schedule, the aorta and tail artery were sampled at three points of a day, and in them NE-induced smooth muscle contraction, NE-induced release of adenyl nucleotides and adenosine, and expressions of mRNAs of several factors related to vasomotion were measured. [J Physiol Sci. 2006;56 Suppl:S230]

抄録全体を表示

We examined the effect of estrogen replacement on the circadian rhythms of feeding, activity and body temperature in ovariectomized rats. Seven-week-old female rats were ovariectomized and were assigned into estradiol- (E2-T) and cholesterol-treated (C-T) groups. Animals were implanted subcutaneously in the intrascapular space with Silastic tubing containing estradiol or cholesterol. A miniature temperature data logger was also implanted in the abdominal cavity. After the one-week recovery period, food intake, activity and intraperitoneal temperature (Tabd) were measured under 12:12h light-dark condition over a week. Daily food intake was significantly higher and daily total activity was lower in C-T rats than E2-T rats. Tabd during the late light phase and early dark phase was higher in C-T rats than E2-T rats, but was not different during the late dark phase and early light phase between the groups. The diurnal pattern of activity level was similar between E2-T and C-T groups, but activity was persistently higher in E2-T rats than C-T rats throughout the day. Food intake was also higher in the C-T rats than E2-T rats throughout the day, but the difference was more significant during the late light period and early dark period. Thus, E2 modifies the diurnal patterns of feeding and body temperature change differently from the activity pattern in ovarietomized rats. [J Physiol Sci. 2006;56 Suppl:S230]

抄録全体を表示

We studied the physiological functions of oxytocin receptor (OXTR) in energy homeostasis using OXTR deficient (oxtr-/-) mice, that we recently generated by genetic engineering.Male oxtr-/- mice developed obesity by 13-week-old. Histrogical analysis of adipose tissue in male oxtr-/- mice showed lipid accumulation in gonadal white adipose tissue (WAT), and most of cells in brown adipose tissue (BAT) were filled with large lipid droplets, suggesting a typical feature in dysfunction of thermogenesis.When oxtr-/- mice were exposed to cold, their rectal temperature rapidly dropped.In oxtr-/- mice, UCP1 expressed in BAT was increased normaly by cold exposure, but the ratio of expressions of α2 to β3 adrenergic receptors (ARs) was altered in comparison with that in wildtype animals. Since these ARs were known to have opposite effects on thermoregulation, the inbalance of ARs might cause this dysfunction.We predicted that OXT/OXTR systems act thermoregulation via central nervous or hormonal systems because both OXT and OXTR were not expressed in mature brown adipocyte, and analysed OXT mRNA expressions in thermogenic ceter of hypothalamus, but no alterations were observed after cold exposure.We further study about the thermoregulatory system controlled by OXT and OXTR. [J Physiol Sci. 2006;56 Suppl:S230]

抄録全体を表示

Heat loss responses are suppressed during dehydration, and hyperosmolality in the extracellular fluid is thought to be involved in this mechanism. In an in-vitro brain slice, warm-sensitive neurons in the medial preoptic area (MPA) are deactivated in a hyperosmotic medium. In contrast, neural activities in the median preoptic nucleus (MnPO) increase during both heat and osmotic stimuli. In the present study, we hypothesized that tail vasodilatation induced by local warming of the MPA in urethane-anesthetized rats would be suppressed by a selective infusion of hypertonic saline to the brain. In addition, rats with the MnPO lesion would lack this suppression. The MPA warming at ∼40 °C increased skin temperature at the tail. Hypertonic saline (1500 mM) infusion into the left internal carotid artery suppressed this response when the MPA was warmed in its dorsolateral area. In MnPO-lesioned rats, there was no effect of hypertonic-saline infusion on the tail skin temperature during the MPA warming. These results indicate that the tail vasodilatation elicited by MPA warming is suppressed during osmotic stimulus. Moreover, the dorsolateral area in the MPA is a crucial site for such a response. The MnPO is also involved in this mechanism. [J Physiol Sci. 2006;56 Suppl:S231]

抄録全体を表示

The neural mechanism of behavioral thermoregulation is poorly understood. In this study, we aimed to establish a new model to analyze behavioral thermoregulation using zebrafish. Zebrafish is a tropical fish living in fresh water. The body length of newborn fish is about 3 mm, and that of adult fish is about 2 cm. We can detect whole-body behavior of newborn fish under microscopic observation. Because the body of newborn fish is transparent, we can directly observe neurons in the brain. There are large numbers of transgenic lines. In addition, it is easy to inhibit the gene expression by injecting antisense morpholino oligonucleotide into embryo within a chorion. We investigated whether newborn fish (3–5 past fertilization) perform thermoregulatory behavior against heating. Breeding water temperature (control) was 28.5^oC. When water temperature was raised to 32.5–40 ^oC, locomotor activity (swimming) much increased. This suggests that fish performs thermoregulatory escape behavior. In conclusion, we established an effective new model to analyze behavioral thermoregulation. [J Physiol Sci. 2006;56 Suppl:S231]

抄録全体を表示

In preceding studies, we have shown that the ratio of the first derivative (dP/dt) of carotid artery pulse (CAP) to the 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 reported the regulatory mechanism of cardiac function during a cold pressor test in athletes last meeting. In the present study, we compared the time course of changes in this cardiac index with previous studies performed using muscle sympathetic nerve activity (MSNA) (Victor et al. 1987; Yamamoto et al. 1992). Fifteen healthy subjects were subjected to the cold pressor test which required them to immerse the right hand in chilly water (4 °C) for 2 min. Mean blood pressure and heart rate changed by almost following the time course as found with MSNA, whereas changes in the cardiac index showed a different time course from that of the latter. Cold stress maximally increased the mean blood pressure and MSNA during the second minute, however, it maximally increased the heart rate and the cardiac index during the 30-60 s period. The time course of change in the cardiac index also differed from that of the heart rate during the recovery period; the cardiac index returned toward the control value but the heart rate was significantly lower than the control value. The findings suggest that the cardiac contractility did not reflect the level of MSNA during a cold pressor test in terms of time course. [J Physiol Sci. 2006;56 Suppl:S231]

抄録全体を表示

Skeletal muscle atrophy occurs in response to unloading condition and is counteracted by mechanical stress to muscle during unloading condition. This study was designed to investigate whether myonuclear number regulates changes in muscle mass induced by altered loading conditions. Adult F344 female rats were assigned to either weight-bearing control or hindlimb-unloaded (HU) group. HU-rats had their hindlimbs suspended for 3 weeks with or without isometric resistance exercise (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. Myonuclear number and fiber size were measured in the medial gastrocnemius muscle using histochemical and immunohistochemical techniques. HU decreased muscle mass and fiber size of all types identified with myofibrillar ATPase staining. IRE ameliorated decrease of muscle mass by 49%. The decreases in fiber size were counteracted by IRE within the range from 33% to 86%. The IRE effectively prevented decrease in fiber size of type IIa (86%) and type IIx (74%) at type I predominant region. Myonuclear number decreased in all types of fibers with HU, but these decreases ameliorated by IRE. These results demonstrate that changes in myonuclear number are associated with changes in myofiber size induced by unloading or intermittent resistance-reloading. [J Physiol Sci. 2006;56 Suppl:S232]

抄録全体を表示

The present study was conducted to examine the effects of regular exercise in childhood and adolescent years on the body weight (BW),and indices of glucose-fatty metabolism in middle-age. Methods: Thirty seven rats were randomly assigned to a childhood exercise group (CEG), which exercised from 5 to 20 weeks of age, an adolescent exercise group (AEG), which exercised from 20 to 35 weeks of age, and a sedentary control group (SCG). The rats exercised voluntarily every day using a rotatory wheel.Result and discussion: Reduction of BW in the AEG was remarkable, and showed the largest reduction of BW 5 weeks following the start of exercise. After the exercise session, food intake in the CEG had a sharp decrease similar to that of the SCG, however a significantly heavier weight of food intake in the AEG continued. Recovery of BW after the ceasing of the exercise session was delayed in the CEG, but those in the AEG quickly recovered. Quick rebounding of BW after the midpoint of the exercise session, which was observed in the AEG, could be explained by both an increase in food intake and a decreased amount of voluntary exercise. Serum leptin concentration in the exercise groups were significantly lower compared to that of sedentary rats, might contribute to the acceleration of food intake. The current result indicated that regular exercise in childhood might be more highly recommended than in the adolescent period, to prevent the incidence of obese-diabetes in middle-age. [J Physiol Sci. 2006;56 Suppl:S232]

抄録全体を表示

We have reported that the net oxygen uptake during outdoor running was about 0.2 lO₂/kg.km independent of running speed in adult students. The purpose of this study was to investigate the effect of artificially increased dead space on the net oxygen uptake during running and recovery on a treadmill. Twelve healthy students performed the graded sub-maximal exercise twice with or without an additional hose. The volume of the hose which was connected to the respiratory mask was 820 ml. The graded exercise tests consisted of running for 10 minutes and recovery for 2 minutes. The values of the net oxygen uptake during treadmill running were almost constant; between 0.167–0.172 lO₂/kg.km, at running speeds of 7.9–11.9 km/h. However, in the results using dead space, the values of net oxygen uptake decreased with an increase in running speed from 0.170 lO₂/kg.km at 9.0 km/h to 0.105 lO₂/kg.km at 12 km/min. These individual net oxygen uptakes at a running speed of 12 km/h were correlated with the percentage values of the maximal oxygen uptake at heart rate 160 beats/min using dead space. The early recovery in oxygen uptake after exercise was not affected by the artificially increased dead space. The results of the present study indicate that the decrease in net oxygen uptake with dead space during running at a faster speed is caused by the decreased capacity in individual respiratory function. Also the effect of the artificially added dead space on oxygen uptake disappears during the early recovery period after exercise. [J Physiol Sci. 2006;56 Suppl:S232]

抄録全体を表示

It is known that exercise training improves high blood pressure in humans. The exercise therapy is recommended to the mild hypertensive patients in the drug treatment. However, the effect of execise is not known in details. Therefore we focused on the action of antihypertensive peptide, atrial natriuretic peptide (ANP). We designed protocol to evaluate the effect of combination of drug treatment and exercise training. Captopril was used as drug, and swimming was used as exercise training. 4 week-old male Wistar rats were purchased for the experiment. They were randomly divided into control group (C), hypertension group (H), captopril administration group (D), swim training group (T) and captopril administration group with swim training (DT). To develop DOCA (deoxycorticosteroneacetate) -salt hypertension, DOCA was administered i.m. to all the groups except C at a dose of 20 mg every week for 2 weeks. Thereafter captopril was orally administered to D and DT at a dose of 50 mg/kg twice a week. T and DT swam for 15 min/day three times a week. The swimming time was increased gradually over the 1-week period from 15 min/day to 90 min/day. They continued swim training for 9 weeks. DOCA-salt hypertensive rats were supplied with 1% saline for drinking water for 11 weeks. After 11 weeks, rats were anesthetized with pentbarbital. And tissue samples were excised. The ANP concentrations in the left ventricule (LV) tended to be higher in T and DT. The heart-to-body weight ratio (HW/BW) of LV was significantly higher in T and DT. These results seems to represent effect of exercise. [J Physiol Sci. 2006;56 Suppl:S232]

抄録全体を表示

It is known that estrogen affects endothelial function, and that the vasodilatory response to reactive hyperemia is enhanced by estrogen. It is still unknown whether the female reproductive hormones have an influence in the regulation of muscle blood flow to the exercising muscle. We hypothesize that estrogen improves muscle blood flow to the exercising muscle under reduced perfusion pressure via improved endothelial function. In the present study, we examined the muscle blood flow response to static handgrip exercise (20% MVC) under reduced perfusion pressure in female and male subjects. In female subjects, we conducted experiments three times; ovulatory (O), luteal (L), and menstrual (M) phases. Perfusion pressure during exercise was reduced by inflating upper arm cuff at 20 or 40 mmHg. We also measured blood flow response following forearm ischemia (upper arm cuff at 200 mmHg for 5 min) in order to evaluate endothelial function. The reduction of blood flow to the exercising muscle induced by the reduction of perfusion pressure was relatively small in O and L than in M and male subjects. The blood flow response following forearm ischemia was higher in O than other conditions. These results suggest that female reproductive hormones might play a role in the regulation of muscle blood flow to the exercising muscle. [J Physiol Sci. 2006;56 Suppl:S233]

抄録全体を表示

The purpose of this study is to detecte the defference between a decline of the attention by the mental fatigue and one by the physical fatigue by event-related potentials (ERPs). Ten healthy college students (mean age: 20 years old) performed a multi steps exercise loading test using a treadmill (physical task) and a continuous additional task using Uchida-Kreperin test paper (mental task). In physical task, the loading strength was increased stepwisely until the heart rate of the subjects reached expected maximum. In the mental task, the subjects were loaded with the continuous additional task for 2 hrs. In this study, audito EPRs and the concentrations of lactic acid in blood, MHPG (3-methoxy-4-hydroxyphenylglycol), and interleukin 6 (IL-6) were adopted as parameters of the fatigue. Audito EPRs were led by source derivation (SD) method. Parameters mentioned above were obtained just before and after each task, and then, 1hr and 2hrs after. The amplitudes of P3a decreased in both of tasks. Lactic acid increased only just after the physical task but MHPG was kept high after the mental task. However, IL-6 did not change in both tasks. These results suggest that a decline of attention in a transient physical fatigue is caused by laktazidose and a decline of attention in transient mental fatigue is caused by the excess-consumption of monoamine in brain. [J Physiol Sci. 2006;56 Suppl:S233]

抄録全体を表示