Yamakawa Takao, Kurauchi Yuki, Hisatsune Akinori, Seki Takahiro, Katsuki Hiroshi
Department of Chemico-Pharmacological Sciences, Graduate School of Pharmaceutical Sciences, Kumamoto University.
Program for Leading Graduate Schools "HIGO (Health life science: Interdisciplinary and Glocal Oriented) Program," Priority Organization for Innovation and Excellence, Kumamoto University.
Biol Pharm Bull. 2018;41(12):1859-1865. doi: 10.1248/bpb.b18-00633.
The lateral hypothalamic area contains neurons expressing neuronal nitric oxide synthase (nNOS), in addition to orexin neurons. Here we examined whether the activity of orexin neurons was regulated by endogenous nitric oxide (NO) in male C57BL/6 mice. Caffeine (30 mg/kg, intraperitoneally (i.p.)) increased the number of orexin neurons positive for c-Fos, a marker of neuronal activity, and also increased the number of NOS/c-Fos-positive cells as identified by reduced nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry and c-Fos immunohistochemistry. Diphenhydramine hydrochloride (10 mg/kg. i.p.) decreased c-Fos-positive orexin neurons but had no significant effect on the number of c-Fos-positive NOS neurons. nNOS inhibitor 7-nitroindazole (25 mg/kg, i.p.) alone increased c-Fos-positive orexin neurons, and combined treatment with caffeine and 7-nitroindazole did not show additive effect in the number of c-Fos-positive orexin neurons. In contrast, 7-nitroindazole decreased c-Fos-positive NOS neurons and attenuated caffeine-induced increase in c-Fos-positive NOS neurons. Sleep deprivation increased c-Fos-positive cells in both orexin neurons and NOS neurons, and 7-nitroindazole did not show additive effect with sleep deprivation in the activation of orexin neurons. Together, these results suggest that endogenous NO negatively regulates the activity of a subset of orexin neurons, and this subset of orexin neurons overlaps with that activated by awakening stimuli.
除了食欲素神经元外，外侧下丘脑区域还含有表达神经元型一氧化氮合酶（nNOS）的神经元。在此，我们研究了雄性C57BL/6小鼠中食欲素神经元的活动是否受内源性一氧化氮（NO）的调节。咖啡因（30mg/kg，腹腔注射（i.p.））增加了c-Fos阳性的食欲素神经元数量（c-Fos是神经元活动的标志物），并且还增加了通过还原型烟酰胺腺嘌呤二核苷酸磷酸（NADPH）黄递酶组织化学和c-Fos免疫组织化学鉴定的NOS/c-Fos阳性细胞数量。盐酸苯海拉明（10mg/kg，i.p.）减少了c-Fos阳性的食欲素神经元，但对c-Fos阳性的NOS神经元数量没有显著影响。单独使用nNOS抑制剂7-硝基吲唑（25mg/kg，i.p.）增加了c-Fos阳性的食欲素神经元，并且咖啡因与7-硝基吲唑联合处理在c-Fos阳性的食欲素神经元数量上未显示出相加效应。相反，7-硝基吲唑减少了c-Fos阳性的NOS神经元，并减弱了咖啡因诱导的c-Fos阳性的NOS神经元增加。睡眠剥夺增加了食欲素神经元和NOS神经元中c-Fos阳性细胞的数量，并且7-硝基吲唑在睡眠剥夺对食欲素神经元的激活作用中未显示出相加效应。总之，这些结果表明内源性NO对一部分食欲素神经元的活动具有负调节作用，并且这部分食欲素神经元与被觉醒刺激激活的神经元部分重叠。
