P物质抑制培养大鼠海马大锥体细胞GABA—激活电流

研究主要探讨P物质（SP）对GABA－激活电流的调制。实验在培养的新生大鼠海马大锥体细胞上进行。应用全细胞膜片箝技术记录GABA激活的内向电流。在被检的大锥体细胞中,有72％（66／92）的神经元对GABA和SP同时敏感,预后SP后,GABA激活电流明显地被抑制,此抑制作用是呈剂量依赖性的。在预加10^-8,10^-7,10^-6,10^-5mol/LSP后,GABA的激活电流分别降低18％,24．8％,25．9％和28％,用SP的拮抗剂 spantide能阻断此种抑制作用,在电极中灌注H7（PKC抑制剂）能取消此抑制作用,上述结果提示：SP对GABA激活电流的抑制作用是SP作用于SP受体,通过胞内第二信使,使GABAA受体通道复合体胞内磷酸化所致。

Substance P depresses GABA-activated currents in cultured hippocampal pyramidal neurons of rats

The purpose of the present study was to explore whether substance P (SP) modulates the response mediated by GABA A receptors. Experiments were carried out on cultured hippocampal pyramidal neurons of rats. GABA activated inward currents were recorded using the whole cell patch clamp techique. The majority of the neurons examined (66/92, 72%) were sensitive to both GABA and SP. When the neurons were treated with SP prior to application of GABA, the GABA activated current ( I GABA ) was inhibited markedly, which was concentration dependent and could be blocked by spantide, an NK1 receptor antagonist. With 10 -8 , 10 -7 , 10 -6 and 10 -5 mol/L SP, L GABA was inhibited by 18%,24.8%,25.9%and 28% respectively,Intracellular application of H7,a potent inhibitor of PKC,abolished inhibition of L GABA by SP,suggesting that the inhibition of L GABA by SP may be a result of intracellular phosphorylation of the GABA A receptor.