Experimental Animals
Online ISSN : 1881-7122
Print ISSN : 1341-1357
ISSN-L : 0007-5124
49 巻 , 4 号
選択された号の論文の12件中1~12を表示しています
Original
  • Terutake NAKAGAWA, Kiyoharu UKAI, Tadashi OHYAMA, Yutaka GOMITA, Hitos ...
    原稿種別: Original
    2000 年 49 巻 4 号 p. 239-249
    発行日: 2000年
    公開日: 2003/11/14
    ジャーナル フリー
    When the hypothalamic ventromedial nucleus and arcuate nucleus were destroyed in rats by treatment with monosodium glutamate in the neonatal stage, increase in the Lee index (body weight 1/3/body length) and in retroperitoneal fat as well as decreases in spontaneous motor activity, food consumption and growth hormone secretion function associated with hypothalamic low body length obesity (monosodium glutamate-treated obesity; MSG-OB) were observed as these rats grew. Treatment with sibutramine at 3 and 10 mg/kg p.o. once a day continuously for 14 days improved these parameters, and the degree of improvement was dose related. The plasma lipid values in MSG-OB rats, which were the same as those in normal rats, were decreased by consecutive administration of sibutramine. Levels of hypothalamic monoamines (MAs) such as norepinephrine, 5-HT (serotonin) and dopamine and their metabolites DOPAC, HVA and 5-HIAA were decreased in MSG-OB rats, and further decrease in them, though slight, was observed with consecutive daily administration of sibutramine, probably as a result of the feedback attributable to an increase in MA in synapses caused by inhibition of MA uptake by sibutramine. These results suggest that sibutramine can activate the MA nervous system by MA uptake inhibition in regions of the brain such as the lateral hypothalamic area and the paraventricular nucleus, which control food intake and sympathetic nerve activity, and the nigrostriatal area related to the extrapyramidal motor system, and thereby exhibit anti-obesity effects in the MSG-OB rat.
  • Shigeru KYUWA, Kazutaka OHSAWA, Hiroshi SATO, Toru URANO
    原稿種別: Original
    2000 年 49 巻 4 号 p. 251-257
    発行日: 2000年
    公開日: 2003/11/14
    ジャーナル フリー
    To understand the virus-cell interactions that occur during murine coronavirus infection, six murine cell lines (A3-1M, B16, CMT-93, DBT, IC-21 and J774A.1) were inoculated with eight murine coronaviruses, including prototype strains of both polytropic and enterotropic biotypes, and new isolates. All virus strains produced a cytopathic effect (CPE) with cell-to-cell fusion in B16, DBT, IC-21 and J774A.1 cells. The CPE was induced most rapidly in IC-21 cells and was visible microscopically in all cell lines tested. In contrast, the coronaviruses produced little CPE in A3-1M and CMT-93 cells. Although most virus-infected cells, except KQ3E-infected A3-1M, CMT-93 and J774A.1 cells, produced progeny viruses in the supernatants when assayed by plaque formation on DBT cells, the kinetics of viral replication were dependent on both the cell line and virus strain; replication of prototype strains was higher than that of new isolates. There was no significant difference in replication of enterotropic and polytropic strains. B16 cells supported the highest level of viral replication. To determine the sensitivity of the cell lines to murine coronaviruses, the 50% tissue culture infectious dose of the coronaviruses was determined with B16, DBT, IC-21 and J774A.1 cells, and compared to that with DBT cells. The results indicate that IC-21 cells were the most sensitive to murine coronaviruses. These data suggest that B16 and IC-21 cells are suitable for large-scale preparation and isolation of murine coronaviruses, respectively.
  • Jun YAMANOUCHI, Etsuko NISHIDA, Shin-ichi ITAGAKI, Seiji KAWAMURA, Kun ...
    原稿種別: Original
    2000 年 49 巻 4 号 p. 259-266
    発行日: 2000年
    公開日: 2003/11/14
    ジャーナル フリー
    To develop an adequate animal model for atherosclerosis in large vessels of patients with diabetes, i.e. diabetic macroangiopathy, we induced diabetes in APA hamsters with a single injection of streptozotocin (SZ) and examined the aorta histopathologically and immunohistochemically. As a result, hyperglycemia and hyperlipidemia were continuously observed for 26 weeks after the SZ injection (WAI) in APA hamsters. Fatty streaks characterized by a subendothelial accumulation of many foam cells were observed, limited to the aortic arches as early as 6 WAI. In addition to larger fatty streaks developing with the duration of diabetes, fibrous plaques and plaques containing calcium deposits or cholesterol clefts developed at 26 WAI. These lesions are generally similar to the atheromatous lesions developed in humans. Moreover, depositions of apolipoprotein E and advanced glycation end-products immunohistochemically detected in the lesions were very similar to those found in humans. The diabetic APA hamster is therefore considered to be a useful model for studying the formation of atheromatous lesions in diabetic patients.
  • Jun YAMANOUCHI, Atsushi TAKATORI, Shin-ichi ITAGAKI, Seiji KAWAMURA, Y ...
    原稿種別: Original
    2000 年 49 巻 4 号 p. 267-274
    発行日: 2000年
    公開日: 2003/11/14
    ジャーナル フリー
    Syrian hamsters of the APA strain (APA hamsters) have recently been shown to have atheromatous lesions in the aortic arches under diabetic condition induced by a single injection of streptozotocin (SZ). In that model, fatty streaks, which are the initial lesions of atherogenesis, develop by 6 weeks after the injection (WAI). In this study, we evaluated plasma lipid concentrations and lipoprotein profiles in diabetic APA hamsters at 6 WAI to reveal the early stage of atherogenesis clinicopathologically. As a result, by biochemical analysis, hyperglycemic APA hamsters showed signs of hypercholesterolemia and hypertriglyceridemia. Low-density lipoprotein (LDL) cholesterol significantly increased, but high-density lipoprotein (HDL) cholesterol significantly decreased. Agarose gel electrophoresis showed an obvious increase in the fractions of chylomicron, LDL and abnormal lipoprotein. Plasma LDL in diabetic animals was in a state more susceptible to oxidization. In addition, a significant increase in glycated LDL was also found in the diabetic animals by enzyme linked immunosorbent assay (ELISA). Moreover, lipid peroxidation product (4-hydroxynonenal (4 HNE))-adducted proteins and advanced glycation end-products (AGE) were immunohistochemically detected in the foam cells of the fatty streaks. These results revealed that diabetic APA hamsters had hyperlipidemia characterized by increases in chylomicron, LDL and abnormal lipoprotein, and suggested that oxidized LDL and/or glycated LDL might be actively uptaken by macrophages and play an important role in the initial stage of atherogenesis.
  • Takeo SATOH, Katsuhiro YAMAGUCHI
    原稿種別: Original
    2000 年 49 巻 4 号 p. 275-280
    発行日: 2000年
    公開日: 2003/11/14
    ジャーナル フリー
    The ocular fundi of the Royal College of Surgeons (RCS) dystrophic rats were examined by conventional fundus photography, fluorescein angiography (FA) and indocyanine green angiography (IA). In the fundus, a reddish colored background was observed in the RCS dystrophic rats at 3 weeks of age. At 9 weeks of age, the background had changed to pale in color. In FA, the RCS dystrophic rats at 3 week of age demonstrated background fluorescence with homogeneous brightness. Fluorescent dye leakage was observed in the late phase of the postinjection period at 9 weeks of age. In IA, the RCS dystrophic rats at 3 weeks of age had background fluorescence with homogeneous brightness, and at 5 weeks of age, spots of hyperfluorescence were scattered over the dark background. At 7 weeks of age, numerous delimited, irregular round spots of hyperfluorescence appeared over the dark background. Such hyperfluorescent lesions had further increased in number and size in the RCS dystrophic rats at 9 weeks of age. In this way, ocular findings related to abnormalities in the retinal pigment epithelium and choroid in the RCS dystrophic rat were demonstrated by fundus photography, fluorescein angiography and indocyanine green angiography.
  • InSurk JANG, KeunKi JUNG, JungSik CHO
    原稿種別: Original
    2000 年 49 巻 4 号 p. 281-287
    発行日: 2000年
    公開日: 2003/11/14
    ジャーナル フリー
    To examine age-related changes in the morphology of intestinal brush border membrane (BBM; microvilli) and specific activities of intestinal BBM enzymes including alkaline phosphatase (ALP), γ-glutamyl transpeptidase (γ-GT), and disacchridase, four groups of Wistar rats were sacrificed at 2.5 wk, 5 wk, 5 mon and 23 mon. In an electron microscopic examination, morphologically a less dense BBM structure in the duodenum of rats aged 23 mon was observed than that of rats aged 5 mon. Specific activity of ALP in the duodenum from 5-mon-old rats was significantly higher than from rats aged 2.5 wk and 23 mon. The mucosal tissues from 5-wk-old rats had significantly higher specific activity of γ-GT than did tissues from the other ages. In sucrase and maltase specific activities, 5-mon-old rats had higher activities of these enzymes than other age groups, especially 2.5-wk- and 23-mon-old rats. There was also a significant effect of site on intestinal BBM enzyme activities in post-weanling rats. Regional gradients of ALP and γ-GT along the entire small intestine (duodenum>jejunum>ileum) were remarkable. Disaccharidase activities peaked in the jejunum and declined toward both the duodenum and ileum. Taken together the result obtained here suggested that 5-mon-old rats had the most elevated intestinal function. This result also strongly indicated that the structure of the intestinal BBM and development of intestinal BBM enzymes in Wistar rats were markedly influenced by age during the postnatal period.
  • Hiroyuki NAITO, Maki INOUE, Junsiro MAKINO
    原稿種別: Original
    2000 年 49 巻 4 号 p. 289-294
    発行日: 2000年
    公開日: 2003/11/14
    ジャーナル フリー
    The present study was undertaken to investigate the relationship between the emotionality and the modulation of ultrasonic vocalizations in Tsukuba High Emotional (THE) and Tsukuba Low Emotional (TLE) strain rat pups 3-18 days old. The THE pups, while isolated from their dam and littermates and placed in a cold environment, emitted ultrasonic isolation calls at a high rate until day 15. In contrast, ultrasound production was at a consistently low level throughout the test period in the TLE pups. The ultrasonic isolation calls of THE pups were attenuated to the same level as those of the TLE pups after administration of diazepam (1 mg/kg, sc), a benzodiazepine receptor agonist, at 6 and 12 days of age. These findings suggest that the high emotionality of the rat pups was reflected largely by the emission of ultrasounds in response to isolation distress rather than the number of the benzodiazepine receptors in the brain that might play a role in physiologic mediation of the rat pup isolation call.
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