微电泳荷包牡丹碱对联合皮层抑制C类纤维传入诱发皮层单位放电的影响

INFLUENCE OF MICOIONTOPHORESIS OF BICUCULLINE ON THE INHIBITION OF ASSOCIATION CORTEX UPON CORTICAL UNIT DISCHARGES EVOKED BY C-FIBERS INPUTS

电刺激大脑皮层前外侧回联合(ALA)对隐神经C类纤维传入诱发的体感皮层单位放电(C-CED)有明显的抑制作用,能使C-CED的积分值显著减小,提示大脑皮层联合区可能对C-CED有调制作用;在体感皮层内微电泳γ-氨基丁酸(GABA)能使C-CED明显减小,积分值衰减,呈剂量效应依赖关系,表明GABA能直接抑制体感皮层内对C类纤维传入反应的神经元,提示这些神经元可能有GABA受体存在;微电泳GABA受体阻断剂荷包牡丹碱(BCL)能使ALA对C-CED的抑制作用显著地减弱,进一步提示电刺激ALA可能引起脑内释放GABA,直接作用体感皮层内对C类纤维传入发生反应的神经元,对C-CED产生抑制作用。

Experiments were performed on cats, anaesthetized with chloralose and immobilized by flaxidil. The results showed that electrical stimulation of cerebral anterior lateral association area(ALA) had an obvious inhibitory effect on the cortical unit discharges which were evoked by C-fibers inputs of saphenous nerve (C-CED) and recorded in the primary somato-sensory cortex(S I), the integration of C-CED being reduction. It was suggested that cerebral association area might play a role in the modulation of C-CED. During microiontophoresis of y-aminobutyric acid(GABA) in S I, C-CED was decreased considerably and its integration reduced, this inhibition was in a dose dependent fashion, indicating that GABA could depress directly the neurons of somatosensory cortex responding to C-fibers inputs and that there were GABA receptors on these neurons. Microiontophoresis of bicuculline(BCL), an antagonist of GABA receptors, could block the inhibitory effect of ALA stimulation on C-CED remarkably, showing further that electrical stimulation of ALA could cause brain to release GABA which acted directly on the neurons of somatosensory cortex responding to C-fibers inputs.