Neural Subtype-dependent Cholinergic Modulation of Neural Activities by Activation of Muscarinic 2 Receptors and G Protein-activated Inwardly Rectifying Potassium Channel in Rat Periaqueductal Gray Neurons
Neural Subtype-dependent Cholinergic Modulation of Neural Activities by Activation of Muscarinic 2 Receptors and G Protein-activated Inwardly Rectifying Potassium Channel in Rat Periaqueductal Gray Neurons
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DOI：
10.1016/j.neuroscience.2022.10.012
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发表时间：
2022-10-29
期刊：
影响因子：
3.3
通讯作者：
Kobayashi，Masayuki
中科院分区：
文献类型：
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作者：
Sugawara，Shiori;Nakaya，Yuka;Kobayashi，Masayuki
乙酰胆碱通过调节中脑导水管周围灰质（vlPAG）的神经活动，在疼痛、睡眠和觉醒周期等功能的调节中起着关键作用。电生理研究表明，胆碱能效应是不一致的记录神经元，特别是在去极化和超极化的静息膜电位（RMP）。这种差异可能是由于RMP的神经亚型依赖性胆碱能调制。为了研究这种可能性，我们使用囊泡GABA转运体（VGAT）-Venus × ChAT-TdTomato大鼠对亚型鉴定的神经元进行全细胞膜片钳记录，并阐明胆碱能作用对RMP的细胞机制。卡巴胆碱的应用以剂量依赖性方式使胆碱能神经元的RMP超极化，但对其他神经亚型（包括GABA能/甘氨酸能和谷氨酸能神经元）的影响要小得多。胆碱能超极化伴随着输入电阻的降低。这些胆碱能效应被AF-DX 384或没食子胺阻断，并被槟榔碱丁-2-炔基酯甲苯磺酸盐模拟，表明卡巴胆碱诱导的胆碱能神经元RMP超极化是通过M2受体介导的。Tertiapin抑制卡巴胆碱诱导的G蛋白激活的内向整流钾通道（GIRK）电流和胆碱能神经元的RMP超极化。胞内应用GDP-β-S可阻断卡巴胆碱诱导的RMP超极化。新斯的明缓慢地使胆碱能神经元的RMP超极化。这些结果表明，VlPAG胆碱能神经元的神经放电被通过M2受体激活诱导的GIRK电流抑制，并且这种胆碱能神经元活动的负反馈调节可以由VlPAG内在释放的乙酰胆碱诱导。
Acetylcholine plays a pivotal role in the regulation of functions such as pain and the sleep and wake cycle by modulating neural activities of the ventrolateral periaqueductal gray (vlPAG). Electrophysiological studies have shown that cholinergic effects are inconsistent among recorded neurons, particularly in the depolarization and hyperpolarization of the resting membrane potential (RMP). This discrepancy may be due to the neural subtype-dependent cholinergic modulation of the RMP. To examine this possibility, we performed whole-cell patch-clamp recordings from subtype-identified neurons using vesicular GABA transporter (VGAT)-Venus × ChAT-TdTomato rats and elucidated cellular mechanisms of cholinergic effects on the RMP. The application of carbachol hyperpolarized the RMP of cholinergic neurons in a dose-dependent manner but had much less of an effect on other neural subtypes, including GABAergic/glycinergic and glutamatergic neurons. Cholinergic hyperpolarization was accompanied by a decrease in input resistance. These cholinergic effects were blocked by AF-DX384 or gallamine and were mimicked by arecaidine but-2-ynyl ester tosylate, suggesting that the carbachol-induced hyperpolarization of the RMP in cholinergic neurons is mediated via M2receptors. Tertiapin suppressed the carbachol-induced G protein-activated inwardly rectifying potassium channel (GIRK) currents and hyperpolarization of the RMP in cholinergic neurons. Intracellular application of GDP-β-S blocked the carbachol-induced hyperpolarization of the RMP. Neostigmine slowly hyperpolarized the RMP in cholinergic neurons. These results suggest that neural firing of vlPAG cholinergic neurons is suppressed by GIRK currents induced via M2receptor activation, and this negative feedback regulation of cholinergic neuronal activities can be induced by acetylcholine, which is intrinsically released in the vlPAG.