Cheng Shi-Bin, Kuchiiwa Satoshi, Gao Hong-Zhi, Kuchiiwa Toshiko, Nakagawa Shiro
Department of Anatomy, Faculty of Medicine, Kagoshima University, Sakuragaoka 8-35-1, Kagoshima 890-8520, Japan.
Neurosci Res. 2003 May;46(1):53-62. doi: 10.1016/s0168-0102(03)00026-9.
Orexins, novel neuropeptides, are exclusively localized in the hypothalamus and implicated in the regulation of a variety of activities, including food intake and energy balance. Nitric oxide (NO), an unconventional neurotransmitter, is widely present in numerous brain regions including the hypothalamus, and has similar physiological roles to those of the orexins. The present study was undertaken to examine the distribution of orexin neurons and the presence of neuronal nitric oxide synthase (nNOS) in the orexin neurons to clarify whether NO interacts with the orexins in the neuronal regulation activities in the Long-Evans rat. We used two double-labeling methods: nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) histochemistry in combination with orexin immunohistochemistry, and double-labeling fluorescent immunohistochemistry for orexin and nNOS. The majority of the orexin immunoreactive neurons were localized mainly in the areas of the dorsomedial hypothalamic nucleus (DMN), the dorsal part of the perifornical nucleus (PEF) and lateral hypothalamic area. The orexin immunoreactive cell bodies were medium in size, and triangular, round, elliptic, and fusiform in shape. The sizes and shapes of orexin neurons in the different parts were similar. Cell bodies coexpressing the orexin and nNOS or NADPH-d were present in the areas of the DMN and the PEF, and the nerve fibers containing orexin and nNOS were distributed in the DMN and PEF, arcuate nucleus (ARN) and ventromedial hypothalamic nucleus (VMH). These results provide morphological evidence that there exists a population of nNOS- or NADPH-d-/orexin-coexpressing neurons in the orexinergic cell group in the hypothalamus, and taken together with previous findings, suggest that NO may play a role in the mechanisms by which orexin neurons regulate food intake and energy balance.
食欲肽是一种新型神经肽，仅在下丘脑表达，参与多种活动的调节，包括食物摄入和能量平衡。一氧化氮（NO）作为一种非传统神经递质，广泛存在于包括下丘脑在内的众多脑区，其生理作用与食欲肽相似。本研究旨在检测食欲肽神经元的分布以及食欲肽神经元中神经元型一氧化氮合酶（nNOS）的表达情况，以阐明在Long-Evans大鼠的神经调节活动中NO是否与食欲肽相互作用。我们采用了两种双重标记方法：烟酰胺腺嘌呤二核苷酸磷酸黄递酶（NADPH-d）组织化学与食欲肽免疫组织化学相结合，以及食欲肽和nNOS的双重荧光免疫组织化学。大多数食欲肽免疫反应性神经元主要定位于下丘脑背内侧核（DMN）、穹窿周核背侧部（PEF）和下丘脑外侧区。食欲肽免疫反应性细胞体大小中等，呈三角形、圆形、椭圆形和梭形。不同部位的食欲肽神经元大小和形状相似。共表达食欲肽和nNOS或NADPH-d的细胞体存在于DMN和PEF区域，含有食欲肽和nNOS的神经纤维分布于DMN、PEF、弓状核（ARN）和下丘脑腹内侧核（VMH）。这些结果提供了形态学证据，表明下丘脑食欲肽能细胞群中存在一群共表达nNOS或NADPH-d与食欲肽的神经元，结合先前的研究结果表明，NO可能在食欲肽神经元调节食物摄入和能量平衡的机制中发挥作用。
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