大鼠低位脑干M受体亚型分析

放射受体结合试验表明脑桥、延髓存在M_1受体(约30～40％)和M_2受体(约60～70％);皮层海马M_1受体为主(约90％),小脑为M_2受体。东莨菪碱对皮层海马M_1受体的亲和力是小脑M_2受体亲和力的22.72倍,阿托品对小脑M_2受体亲和力是对皮层海马M_1受体亲和力的3.89倍。结果提示东莨菪碱、阿托品分别对M_1、M_2受体有一定的选择性。

ANALYSIS OF MUSCARINIC RECEPTOR SUBTYPES IN RAT BRAIN STEM

Radioligand binding experiments using 3H-QNB and 3H-PZ were Performed on the cortex and hippocampus, Pons, medulla oblongata and cerebellum of Wistar rat brains. It was found that the M1 cholinergic recePtor accounted for approximately 90% the total muscarinic receptors in the cortex and hiPPo-camPus, and the M2 accounted for only about 10%. In the Pons and medulla oblongata, the MI cholinergic receptor accounted for appoximately 30-40% the total muscarinic receptors in these 2 brain parts; and the M2 accounted for about 60-70%. When separate scoPolamine , atro,Pine , pirenzePine and AF-DX 116 were added to comPete against the 3H- labelled reagents in binding to the receptors in the four parts of brain, the Pki values obtained showed that the affinities of scoPolamine and PirenzePine for cortex-hiPPocamp-us ( Ml ) were 22.7 and 303.3 times higher than those for cerebellum ( M2 ) . The affinities of AF-DX 116 and atropine for cerebellum were respectively 31.6 times and 3.89 times higher than those for cortex-hiPPocamPus . These results suggest that scoPolamine has higher selectivity for the M1 than for the Mi, while the selectivity of atroPine is higher for the M2 than the M1.