γ—氨基丁酸在联合皮层抑制C类纤维皮层诱发电位效应中的作用

电刺激猫大脑皮层前外侧回联合区(ALA)对隐神经C类纤维传入引起的体感皮层(SI)诱发电位(C-CEP)有明显的抑制作用;侧脑室注射γ-氨基丁酸(GABA)能使C-CEP的幅值显著变小,潜伏期延长,表明GABA对C-CEP也有抑制作用;侧脑室注射GABA受体拮抗剂荷包牡丹硷后,电刺激ALA对C-CEP的抑制作用明显减弱,提示内源性GABA的释放可能参与大脑皮层联合区对C-CEP的调制过程。

ROLE OF GABA IN THE INHIBITORY EFFECT OF ASSOCIATION CORTEX ON THE CORTICAL EVOKED POTENTIALS ELICITED BY C-FIBER INPUTS

The experiments were carried out on cats anaesthetized by chloralose and immobilized by flaxedil. The inhibition of cortical potentials, which were evoked by C-fiber inputs of saphenous nerve (C-CEP) and recorded on somatosensory cortex (SI), induced by electrical stimulation of anterior lateral association area (ALA) was observed. In order to study whether gama-aminobutyric acid(GABA) had an inhibitory effect on C-CEP and involved in the inhibition of C-CEP produced by ALA stimulation, bicuculline and GABA were injected intraventricularly. The results showed that GABA could decrease the amplitude of C-CEP in a dose-dependent manner and increase its latency. The stimulation of ALA had also an inhibitory effect on C-CEP, and bicuculline, an antagonist of GABA receptor, could partially block this effect. It was suggested that both ALA stimulation and GABA could inhibit C-CEP and endogenous GABA might associate with the inhibitory effect of association cortex on C-CEP.