Lamour Y, Dutar P, Jobert A
Brain Res. 1983 Dec 19;289(1-2):157-67. doi: 10.1016/0006-8993(83)90016-1.
The properties of two populations of acetylcholine-sensitive neurons, defined by their different laminar distribution (group A, layers V and upper VIa; group B, layer VIb and underlying white matter) were studied in the SmI cortex of urethane-anesthetized rats. The spontaneous activity of group B neurons was significantly lower than in group A. The proportion of neurons excited by iontophoretic acetylcholine, the duration and the pharmacological properties of the excitations were the same in both groups. The dose-response curves obtained for sets of neurons of both groups, recorded with the same electrode, had comparable slopes. Carbachol had a greater potency than acetylcholine in both groups. In contrast, the latency of the response to acetylcholine was significantly shorter in group B. The amount of current required to increase the spontaneous discharge rate of a given neuron by 200% was lower in group B than in group A. These data suggest that the relative change in firing frequency induced by a given cholinergic input is likely to be larger in group B than in group A. Finally, neuronal excitations could still be obtained in both groups when acetylcholine was applied 300 micron, but not 600 micron, from the cell body, suggesting that the spatial distribution of acetylcholine receptors is similar in groups A and B.
在乌拉坦麻醉大鼠的SmI皮质中，研究了两组乙酰胆碱敏感神经元的特性，这两组神经元由其不同的分层分布定义（A组，V层和VIa层上部；B组，VIb层及下方白质）。B组神经元的自发活动明显低于A组。两组中由离子电泳乙酰胆碱激发的神经元比例、激发的持续时间和药理特性相同。用同一电极记录的两组神经元的剂量-反应曲线斜率相当。在两组中，卡巴胆碱的效力均高于乙酰胆碱。相比之下，B组对乙酰胆碱反应的潜伏期明显更短。将给定神经元的自发放电率提高200%所需的电流量，B组低于A组。这些数据表明，给定胆碱能输入引起的放电频率相对变化在B组可能比在A组更大。最后，当从细胞体施加乙酰胆碱的距离为300微米而非600微米时，两组仍可获得神经元兴奋，这表明A组和B组中乙酰胆碱受体的空间分布相似。
