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目的：观察第三脑室微量注射甲硫－脑啡肽（ｍｅｔ－ｅｎｋｅｐｈａｌｉｎ，Ｍｅｔ－Ｅｎｋ）对脾交感神经放电活动的影响。方法：用ｕｒｅｔｈａｎｅ和α－ｃｈｌｏｒａｌｏｓｅ麻醉的雄性Ｓｐｒａｇｕｅ－Ｄａｗｌｅｙ大鼠，于第三脑室分别微量注射Ｍｅｔ－Ｅｎｋ１μｇ和１００μｇ。结果：脾交感神经放电活动的双向调节作用，即微量注射１μｇＭｅｔ－Ｅｎｋ时脾交感神经冲动数会减少，而注射１００μｇＭｅｔ－Ｅｎｋ时脾交感神经冲动数会增多。事先静脉注射阿片受体阻断剂纳络酮（ｎａｌｏｘｏｎｅ，Ｎａｌ）均可以阻断这两种效应，但单独使用Ｎａｌ对脾交感神经兴奋性没有影响。随脾交感神经冲动数的增多和减少，血压亦有一定程度的升高和降低，但体温无明显变化。结论：Ｍｅｔ－Ｅｎｋ可以在中枢神经系统内通过阿片受体介导的通路调节脾交感神经的兴奋性。
Objective: To observe the effects of microinjection of met-enkephalin (Met-Enk) on splenic sympathetic nerve activity in the third ventricle. Methods: Male Sprague-Dawley rats anesthetized with urethane and α-chloralose were injected with 1 μg and 100 μg Met-Enk in the third ventricle respectively. RESULTS: The bi-directional modulation of splenic sympathetic nerve activity decreased the number of splenic sympathetic impulses at 1 μg Met-Enk and increased the number of splenic sympathetic impulses upon injection of 100 μg Met-Enk. Prior intravenous opioid receptor blocker naloxone (Nal) blocked both effects, but Nalpha alone had no effect on splenic sympathetic excitability. With the spleen sympathetic nerve impulses increased and decreased, blood pressure also increased and decreased to some extent, but no significant changes in body temperature. Conclusion: Met-Enk regulates the excitability of splenic sympathetic nerve via the opioid receptor-mediated pathway in the central nervous system.