Ye J H, Ren J, Liu P L, McArdle J J
Department of Anesthesiology, New Jersey Medical School (UMDNJ), Newark 07103-2714, USA.
Brain Res. 1998 Jun 15;796(1-2):53-62. doi: 10.1016/s0006-8993(98)00317-5.
Properties of whole-cell glycine currents (IGly) of ventral tegmental area (VTA) neurons from 3- to 7-day old Sprague-Dawley rats were investigated with the patch-clamp technique. Ninety-three percent of the 126 neurons examined produced IGly in response to glycine. For 70% of these neurons, IGly did not decay in response to a threshold concentration of glycine (1-5 microM). At elevated glycine concentrations, IGly consistently decayed from a peak to a steady state (SS). IGly increased in amplitude sigmoidally as a function of the concentration of agonist with an EC50 of 32 microM. Strychnine (STR), when co-applied with glycine after a prepulse of STR, suppressed both the peak and SS IGly noncompetitively. In the absence of a prepulse, STR had a smaller effect on peak IGly while increasing its decay rate; the SS amplitude decreased. These STR effects were concentration dependent with an IC50 of 31 nM and 184 nM STR for the peak and SS IGly, with prepulse, respectively, and 732 nM and 193 nM for the peak and SS IGly, respectively, without prepulse. Picrotoxin (PTX) co-applied with glycine suppressed both the peak and the SS IGly with an IC50 of 25 microM. In contrast to STR, 1 min preincubation with PTX had no effect on IGly. Thus, PTX acts on the open channel. The inhibitory effects of both STR and PTX on IGly did not depend on the membrane potential.
采用膜片钳技术研究了3至7日龄Sprague-Dawley大鼠腹侧被盖区（VTA）神经元全细胞甘氨酸电流（IGly）的特性。在检测的126个神经元中，93%的神经元对甘氨酸产生IGly。在这些神经元中，70%的神经元对阈浓度的甘氨酸（1 - 5 microM）产生的IGly不衰减。在甘氨酸浓度升高时，IGly会从峰值持续衰减至稳态（SS）。IGly的幅度随激动剂浓度呈S形增加，EC50为32 microM。士的宁（STR）在预脉冲后与甘氨酸共同施加时，非竞争性地抑制IGly的峰值和稳态值。在没有预脉冲的情况下，STR对IGly峰值的影响较小，但会增加其衰减率；稳态幅度降低。这些STR效应具有浓度依赖性，预脉冲时对IGly峰值和稳态值的IC50分别为31 nM和184 nM STR，无预脉冲时分别为732 nM和193 nM STR。与甘氨酸共同施加的印防己毒素（PTX）抑制IGly的峰值和稳态值，IC50为25 microM。与STR不同，PTX预孵育1分钟对IGly无影响。因此，PTX作用于开放通道。STR和PTX对IGly的抑制作用均不依赖于膜电位。
