Fiszman M L, Barker J L, Jones S V
Laboratory of Neurophysiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.
Brain Res. 1991 Aug 23;557(1-2):1-4. doi: 10.1016/0006-8993(91)90108-8.
Electrophysiological recordings of responses to muscarinic receptor stimulation in cultured embryonic hippocampal neurons have been largely unsuccessful to date. In this study muscarinic receptor binding was demonstrated in 2-week-old embryonic rat hippocampal cultures. Using whole-cell patch-clamp recording we found that 1-5 microM carbachol produced multiple effects including depolarization, increased action potential firing rate, increased synaptic activity and a reduction in the amplitude of medium-duration afterhyperpolarizations. Voltage-clamp analysis revealed a time-dependent current relaxation with hyperpolarizing steps from a holding potential of about -40 mV which was inhibited by 10 microM muscarine or 50 microM carbachol and had characteristics similar to those of the m-current. Both atropine and pirenzepine inhibited all of these effects indicating that these cholinergic actions were mediated by muscarinic receptors. This study shows that muscarinic responses obtained classically in hippocampal brain slices can also be produced in cultured hippocampus.
迄今为止，在培养的胚胎海马神经元中对毒蕈碱受体刺激反应的电生理记录在很大程度上并不成功。在本研究中，在2周龄的胚胎大鼠海马培养物中证实了毒蕈碱受体结合。使用全细胞膜片钳记录，我们发现1-5微摩尔的卡巴胆碱产生多种效应，包括去极化、动作电位发放率增加、突触活动增加以及中等时程超极化后电位幅度减小。电压钳分析显示，从约-40毫伏的钳制电位进行超极化步阶时，电流随时间依赖性松弛，该松弛被10微摩尔的毒蕈碱或50微摩尔的卡巴胆碱抑制，并且具有与M电流相似的特征。阿托品和哌仑西平均抑制所有这些效应，表明这些胆碱能作用是由毒蕈碱受体介导的。这项研究表明，经典地在海马脑片中获得的毒蕈碱反应也可以在培养的海马中产生。
