Department of Physiology, Monash University, Clayton, VIC 3800, Australia.
Neuroendocrinology. 2010;91(3):223-38. doi: 10.1159/000262283. Epub 2009 Nov 25.
BACKGROUND/AIMS: The aim was to determine whether genetic selection of sheep for body composition could be accounted for by changes in the level of expression of genes for appetite-regulating peptides in the hypothalamus. We examined gene expression in the hypothalamus of genetically lean, normal and fat ewes (n = 5/group).
Plasma growth hormone (GH) and metabolic indicators were measured and gene expression in brains was quantified by in situ hybridization.
Body weight and voluntary food intake (VFI) were similar between groups, but lean and fat animals respectively had low and high indices of adiposity. GH levels were higher in lean and fat animals than in controls. In the arcuate nucleus (ARC), neuropeptide Y (NPY) expression/cell was higher in the lean animals than in normal animals, but overall NPY expression was similar in fat and normal animals. Pro-opiomelanocortin (POMC) and leptin receptor (ObRb) expression in the ARC was similar across groups. Orexin (ORX) and melanin-concentrating hormone (MCH) expression was inversely correlated to adiposity, being higher in lean and lower in fat animals.
Expression of genes for orexigenic neuropeptides is altered in a consistent way. Energy expenditure is reduced by MCH but increased by ORX, so increased expression of the latter may cause increased energy expenditure in the lean animals and vice versa in the fat animals.
背景/目的：本研究旨在确定通过改变下丘脑食欲调节肽基因的表达水平，是否可以对绵羊的体组成进行遗传选择。我们检测了遗传上瘦型、正常型和肥胖型绵羊（每组 5 只）下丘脑的基因表达。
测量了血浆生长激素（GH）和代谢指标，并通过原位杂交定量了脑内的基因表达。
各组间体重和自愿采食量（VFI）相似，但瘦型和肥胖型动物的肥胖指数分别较低和较高。GH 水平在瘦型和肥胖型动物中高于对照组。在弓状核（ARC）中，瘦型动物的神经肽 Y（NPY）表达/细胞高于正常型动物，但肥胖型和正常型动物的总 NPY 表达相似。ARC 中的促黑细胞激素（POMC）和瘦素受体（ObRb）表达在各组间相似。食欲肽（ORX）和黑色素浓缩激素（MCH）的表达与肥胖呈负相关，在瘦型动物中较高，在肥胖型动物中较低。
食欲肽基因的表达以一致的方式发生改变。MCH 降低能量消耗，但 ORX 增加能量消耗，因此后者的表达增加可能导致瘦型动物的能量消耗增加，反之亦然。
