【摘要】 为探讨下丘脑 -垂体 -肾上腺轴在野生小哺乳动物产热中的调节作用 ,对正常及肾上腺去除的长爪沙鼠进行了冷暴露研究。正常雄性长爪沙鼠在急性冷暴露 ( 4± 1℃ ,1天 )条件下 ,下丘脑促肾上腺皮质激素释放激素的合成和释放没有显著变化 ,肾上腺皮质酮含量增加 4 5 8% ,差异显著 ,血清皮质酮水平有增加趋势 ;慢性冷暴露 ( 4± 1℃ ,3周 )后 ,肾上腺皮质酮含量增加到对照的 2 14倍 ,血清皮质酮含量维持较高水平。肾上腺去除的长爪沙鼠冷暴露 3周后 ,褐色脂肪组织 (BAT)产热 (细胞色素C氧化酶活力、线粒体GTP结合数量 )增加 ,下丘脑促甲状腺激素释放激素的合成和释放、血清三碘甲腺原氨酸水平以及血清去甲肾上腺素的浓度均有增加的趋势。表明冷暴露条件下长爪沙鼠肾上腺皮质酮的合成和释放增加 ,从而抑制BAT的产热 ,皮质酮对BAT产热的抑制部分是通过抑制下丘脑 -垂体 -甲状腺轴激素的合成和分泌以及抑制交感神经系统的活动而实现的。更多还原

【Abstract】 We studied the effect of hormones in hypothalamic pituitary adrenal (HPA) axis on thermogenesis of brown adipose tissue (BAT) in Mongolian gerbils ( Meriones unguiculatus ). In experiment 1, intact adult male Mongolian gerbils were divided into three groups randomly: a control group kept in room temperature (24±2℃) and acute and chronic cold exposed groups kept in 4±1℃ for 1 day and 3 weeks, respectively. Corticotropin releasing hormone (CRH) content in the hypothalamus and median eminence did not change significantly while corticosterone in adrenal increased by 45 8%, and corticosterone in serum tended to increase in the acute cold exposed animals as compared with controls. After 3 weeks of cold exposure, CRH in the median eminence and in hypothalamus showed no difference from that of control animals. CRH in median eminence was significantly lower than that of acute cold exposed animals, and corticosterone in adrenal was 114% more than acute cold exposed animals while corticosterone in serum kept at the same level as that of acute cold exposed animals. These results suggest that cold expose did not activate the secretion of CRH in hypothalamus, but stimulated the synthesis and release of corticosterone in the adrenal of Mongolian gerbils. In experiment 2, adrenalectomized and sham adrenalectomized gerbils were exposed to cold (4±1 ℃) for 3 weeks. Thermogenic parameters of BAT and concentrations of hormones in HPT axis and norepinephrine in serum were measured. In the adrenalectomized gerbils, the cytochrome C oxidase activity in BAT and liver, and the capacity of GTP binding to BAT mitochondria were higher markedly than that of sham adrenalectomized gerbils. Both TRH in median eminence and triiodothyronine in serum increased, as norepinephrine in serum. These results suggest that corticosterone may have restrained thermogenesis of BAT and liver in gerbils exposed to cold, and that the effects are partly due to the lower secretion of hormones in the HPT axis and the activity of sympathetic nervous system under cold conditions.更多还原