中脑导水管周围灰质在肌梭传入镇痛中的作用

目的　分析PAG在肌梭传入镇痛中的作用及有关的神经递质。方法　以大鼠脊髓背角广动力型(WDR)神经元伤害性诱发反应(C-反应)为痛指标，采用细胞外记录单位放电、核团损毁及核团内微量注射药物的方法，观察静脉注射琥珀胆碱(SCH)所诱发的肌梭传入对WDR神经元C-反应的影响。结果　静脉注射SCH可兴奋大多数PAG神经元的自发放电活动，而对WDR神经元C-反应呈明显的抑制作用；损毁双侧PAG腹外侧区后，静脉注射SCH对WDR神经元C-反应呈明显的抑制作用；损毁双侧PAG腹外侧区后，静脉注射SCH对WDR神经元C-反应的抑制分别呈现减弱、减弱、增强作用。结论　PAG在肌梭传入镇痛中起着重要作用；阿片肽类物质及γ-氨基丁酸能神经元参与了PAG在肌梭传入镇痛中的作用。

The role of PAG in analgesia produced by muscle spindle afferent information

In the present experiment, the late train discharges(C-response) of the wide dynamic range(WDR) neurons evoked by intense electrial stimulation of the skin were taken as a nocicepive response.The effects of bilateral lesion of ventrolateral PAG and microinjection of naloxone, GABA or BICM into it on the inhibition produced by muscle spindle afferents impulse elicited by injecting introvenously succinylcholine (SCH) were observed.We found that the C-response of WDR neurons could be inhibited remarkably by introvenous injection of SCH,while the spontaneous discharge of most PAG neurons could be excited.After lesion of ventrolateral PAG,the inhibition induced by injection of SCH on the C-response of WDR neurons decreased remarkably.The results indicate that PAG plays an important role in the analgesia produced by muscle spindle afferent information.After bilateral microinjection of naloxone,GABA or BICM into PAG,the inhibition induced by injection of SCH decreased,decreased and increased respectively.The results show that the opiate transmitter and GABA ergic fibers take part in the process.