Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico.
Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Ciudad de México 04510, Mexico.
Prog Neurobiol. 2024 Nov;242:102682. doi: 10.1016/j.pneurobio.2024.102682. Epub 2024 Oct 26.
The hypothalamic arcuate nucleus (ARC) contains two main populations of neurons essential for energy homeostasis: neuropeptide Y (NPY) neurons, which are orexigenic and stimulate food intake, and proopiomelanocortin (POMC) neurons, which have an anorexigenic effect. Located near the blood-brain barrier, ARC neurons sense blood-borne signals such as leptin, insulin, and glucose. Exogenous substances, such as nicotine, can also alter ARC neuron activity and energy balance. Nicotine, an addictive drug used worldwide, inhibits appetite, and reduces body weight, although its mechanisms in regulating ARC neurons are not well understood. Using electrophysiological techniques in brain slices, we investigated the effects of nicotine on POMC and NPY neurons at physiological glucose concentrations. We found that nicotine increased the firing rate of POMC and inhibited NPY neurons. Additionally, nicotine-enhanced glutamatergic inputs to POMC cells and GABAergic inputs to NPY neurons, mediated by α7 and α4β2 nicotinic acetylcholine receptors (nAChRs), respectively. These findings can contribute to the understanding of the anorexigenic effects of nicotine in smokers.
下丘脑弓状核(ARC)包含两个对能量稳态至关重要的主要神经元群体:神经肽 Y(NPY)神经元,它是食欲刺激物,刺激食物摄入,和前阿黑皮素原(POMC)神经元,它具有抑制食欲的作用。ARC 神经元位于血脑屏障附近,可感知血液中的信号,如瘦素、胰岛素和葡萄糖。外源性物质,如尼古丁,也可以改变 ARC 神经元的活动和能量平衡。尼古丁是一种在全球范围内被滥用的成瘾性药物,它可以抑制食欲,减轻体重,尽管其调节 ARC 神经元的机制尚不清楚。我们使用脑片的电生理技术,在生理葡萄糖浓度下研究了尼古丁对 POMC 和 NPY 神经元的影响。我们发现尼古丁增加了 POMC 神经元的放电率,并抑制了 NPY 神经元。此外,尼古丁增强了 POMC 细胞的谷氨酸能传入和 NPY 神经元的 GABA 能传入,分别由α7 和α4β2 烟碱型乙酰胆碱受体(nAChRs)介导。这些发现有助于理解尼古丁在吸烟者中的抑制食欲作用。