冬季和夏季达乌尔黄鼠下丘脑c-Fos、nNOS和NPY表达及血清激素水平比较

Comparison of Hypothalamic c-Fos-,nNOS-and NPY-IR Expression and Serum Hormones Level of Daurian Ground Squirrel Between Winter and Summer

动物通过中枢和外周信号的相互作用调节食欲,达乌尔黄鼠(Spermophilus dauricus)是一种典型的贮脂类冬眠动物。为探究动物冬眠期调节食欲的神经内分泌反应与夏季活动期相比有何不同,通过免疫组织化学方法比较冬季和夏季达乌尔黄鼠下丘脑c-Fos、神经元型一氧化氮合酶(n NOS)以及神经肽Y(NPY)表达,同时用酶联免疫方法检测血清中调节食欲的胃饥饿素(GHRL)和促肾上腺激素释放激素(CRH)浓度。结果发现:冬季达乌尔黄鼠下丘脑弓状核(ARC)、室旁核(PVN)、腹内侧核(VMH)、下丘脑外侧区(LHA)和背内侧核(DMH)的c-Fos-IR神经元表达显著低于夏季;除ARC外,n NOS-IR神经元在其他脑区表达也显著低于夏季;冬季ARC和VMH的NPY-IR神经元表达显著低于夏季,但LHA表达高于夏季;冬季血清GHRL浓度显著低于夏季,但CRH浓度高于夏季。这些结果表明冬季达乌尔黄鼠下丘脑神经元活动减弱,NO、NPY、GHRL和CRH释放水平与夏季不同,呈现出对冬眠的生理性适应。该结果有助于认识冬眠动物中枢和外周对食欲的季节性调节。

Appetite is regulated by an interaction between central and peripheral signals.The Daurian ground squirrel(Spermophilus dauricus)is a typical fat-storing hibernating animal.To explore the difference in appetite related neuroendo⁃crine response in hibernating animal between winter(hibernating period)and summer(active period),the immunoreactive(IR)neuron expression of c-Fos,neuronal nitric oxide synthase(nNOS),neuropeptide Y(NPY)of the hypothalamus us⁃ing immunohisochemistry methods,and the concentration of serum ghrelin(GHRL)and corticotropin releasing hormone(CRH)using enzyme-linked immunosorbent assay(ELISA)methods were examined in Daurian ground squirrels during summer and winter.In contrast to summer,c-Fos-IR expression in the arcuate nucleus(ARC),paraventricular nucleus(PVN),ventromedial hypothalamus(VMH),lateral hypothalamic area(LHA),and dorsomedial hypothalamic nucleus(DMH)decreased significantly in winter.The nNOS-IR neurons were expressed in the same way except for the ARC.The NPY-IR neurons in the ARC and VMH in winter were significantly lower than those in summer,while the LHA NPY-IR neu⁃rons in winter was significantly higher than those in summer.Furthermore,the serum GHRL concentration in winter were significantly lower than that in summer,while the serum CRH concentration in winter were significantly higher than that in summer.These results suggest that the Daurian ground squirrel exhibits weak neuronal activation in the hypothalamus dur⁃ing winter,and the release of nitric oxide,NPY,GHRL and CRH exhibit a flexible physiological adaptation to hibernation.These findings will allow us to better comprehend the seasonal modulation of appetite by central and peripheral system in hi⁃bernating animals.