GABA改变额叶皮层机能状态对PAG神经元电针效应的影响

EFFECT OF CHANGING THE FUNCTIONAL STATE OF FRONTAL CORTEX BY GABA ON THE ACUPUNCTURE EFFECT OF PAG NEURONS

大脑皮层体感Ⅰ区、Ⅱ区、额叶皮层等参与疼痛及针刺镇痛的研究已有不少报导。也有研究表明PAG是电刺激脑、和吗啡、内啡肽、脑内微量注射产生镇痛作用的最有效部位。PAG内阿片受体分布密集,内啡肽含量很高。电刺激大鼠PAG能进一步增强针刺镇痛的效果。损毁大鼠的PAG后,针刺镇痛效应明显降低,因而认为PAG参与针刺镇痛。

The aim of this paper is to investigate the corticofugal modulation of nucleus periaqueductal gray(PAG) after electroacupuncture by topical administration of GABA on frontal cortex. Experiments were carried out on restrained rabbits immobilized with gallamine. Electrial stimulation of the n. suralis was used as the noxious stimulation. Single unit activites of PAG neurons were record with glass microelectrodes extracellularly.'Zusanli' and'Huantiao' points were stimulated by the electroacupuncture bilaterally. GABA was applied topically by means of 3×3mm^2 filter paper and placed on the frontal cortex. It was shown that the responses of most PAG neurons evoked by noxious stimulation were inhibited after simple electroacupuncture. On the contrary, the acupuncture effect on PAG neurons was abolished when GABA was administed on frontal cortex. However, the effect of saline control resembled that of simple acupuncture. This result suggested that the corticofugal modulation from frontal cortex may play a role in acupuncture analgesia.