Williams L M, Adam C L, Mercer J G, Moar K M, Slater D, Hunter L, Findlay P A, Hoggard N
Molecular Neuroendocrinology Unit, Rowett Research Institute, Bucksburn, Aberdeen, UK.
J Neuroendocrinol. 1999 Mar;11(3):165-9. doi: 10.1046/j.1365-2826.1999.00293.x.
Leptin, a protein secretory product of adipocytes, is important in appetite control, energy balance and reproduction. In rodents, the physiological effects of leptin are centrally mediated, in part via the neuropeptide Y (NPY) system in the hypothalamus. The role of leptin in ruminants, where appropriate nutrition and reproductive status are of major economic concern, is largely unknown. To elucidate the function of leptin in sheep we have investigated putative sites of action for leptin in the brain and pituitary gland using both in-situ hybridization to detect expression of the signalling form of the leptin receptor (OB-Rb) and in-vitro autoradiography using (125I)leptin to detect sites of specific leptin binding. OB-Rb gene expression occurred in the hippocampus, cerebral cortex, preoptic area, stria terminalis and choroid plexus, and within the hypothalamus in the paraventricular (PVN), ventromedial (VHM) and arcuate (ARC) nuclei. OB-Rb gene expression in the ovine pituitary gland was not detected by in-situ hybridization. Sites of OB-Rb and NPY gene expression were compared using both in-situ hybridization on adjacent sections containing the arcuate and ventromedial nuclei, and dual in-situ hybridization on sections containing these areas. In serial sections, OB-Rb expression was found to correspond closely with that of NPY over the arcuate nuclei. Using dual in-situ hybridization, NPY expressing neurones in the arcuate nuclei were also positive for OB-Rb gene expression. Therefore, it appears that leptin may partly act via OB-Rb located on NPY neurones in the sheep hypothalamus as in the rodent.
瘦素是脂肪细胞分泌的一种蛋白质产物，在食欲控制、能量平衡和生殖过程中发挥着重要作用。在啮齿动物中，瘦素的生理作用部分是通过下丘脑的神经肽Y（NPY）系统进行中枢调节的。在反刍动物中，适当的营养和繁殖状况是主要的经济关注点，而瘦素在其中的作用很大程度上尚不明确。为了阐明瘦素在绵羊中的功能，我们使用原位杂交技术检测瘦素受体信号形式（OB-Rb）的表达，以及使用（125I）瘦素进行体外放射自显影来检测瘦素特异性结合位点，从而研究了瘦素在绵羊大脑和垂体中的假定作用位点。OB-Rb基因表达出现在海马体、大脑皮层、视前区、终纹床核和脉络丛，以及下丘脑的室旁核（PVN）、腹内侧核（VHM）和弓状核（ARC）。原位杂交未检测到绵羊垂体中OB-Rb基因的表达。我们使用包含弓状核和腹内侧核的相邻切片进行原位杂交，以及在包含这些区域的切片上进行双重原位杂交，比较了OB-Rb和NPY基因的表达位点。在连续切片中，发现弓状核上OB-Rb的表达与NPY的表达密切对应。使用双重原位杂交技术，弓状核中表达NPY的神经元对OB-Rb基因表达也呈阳性。因此，与啮齿动物一样，瘦素可能部分通过位于绵羊下丘脑NPY神经元上的OB-Rb发挥作用。
