Orexin gene expression and regulation by photoperiod in the sheep hypothalamus
Orexin gene expression and regulation by photoperiod in the sheep hypothalamus
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DOI：
10.1016/s0167-0115(01)00347-0
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发表时间：
2002-03-15
影响因子：
--
通讯作者：
Adam, CL
中科院分区：
文献类型：
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作者：
Archer, ZA;Findlay, PA;Adam, CL
反刍动物下丘脑食欲素基因的表达尚未见报道。在这里，我们描述了本地化的preproorexin mRNA在绵羊下丘脑外侧区（LHA）和不确定性（ZI）使用原位杂交。下丘脑的食欲素基因表达的定位是相似的，在绵羊啮齿动物模型。由于绵羊的食欲是季节性的（光周期性）调节，我们比较了自由饲养（食物摄入量比SD高20%，LD）和食物限制绵羊（50%活重维持11周）的长（LD）和短日（SD）光周期之间的preproorexin mRNA的量。基因表达在SDs高于LDs，但不受慢性食物限制。在第二项研究中，去势羊下丘脑食欲素基因表达不受4天禁食的影响，与性腺类固醇（雌二醇）替代无关，也不受性腺类固醇本身的影响。结果表明食欲素基因表达对光周期的敏感性，但当食欲特征性低且对食物摄入量的变化不敏感时，在SD中发生上调。这支持了食欲素在食欲调节和纠正负能量平衡中可能不起主要作用的概念，但由于绵羊只在SD中繁殖，因此它们在季节性生殖激活中的作用值得进一步研究。(C)2002 Elsevier Science B.V.保留所有权利。
Hypothalamic orexin gene expression has not been reported in the ruminant. Here, we describe the localization of preproorexin mRNA in the ovine lateral hypothalamic area (LHA) and zona incerta (ZI) using in situ hybridization. The hypothalamic localization of the orexin gene expression was similar in sheep to rodent models. Since appetite in sheep is seasonally (photoperiodically) regulated, we compared the amounts of preproorexin mRNA between long- (LD) and short-day (SD) photoperiods in both freely feeding (food intake is 20% higher in LD than SD) and Food-restricted sheep (50% liveweight maintenance for 11 weeks). Gene expression was higher in SDs than in LDs but was not affected by chronic food restriction. In a second study, hypothalamic orexin gene expression in castrate sheep was not affected by a 4-day fast, irrespective of gonadal steroid (estradiol) replacement, and was not affected by the gonadal steroid per se. The results demonstrate the sensitivity of orexin gene expression to photoperiod, but up-regulation occurs in SDs when the appetite is characteristically low and no sensitivity to imposed changes in food intake. This supports the concept that orexins may not have a primary role in appetite regulation and correction of negative energy balance but since the sheep breed only in SDs, their role in seasonal reproductive activation deserves further study. (C) 2002 Elsevier Science B.V. All rights reserved.