老年大鼠脑M_1亚型受体的变化及黄芪的调节作用

The Regulatory Action of Astragalus membranaceus on Brain M1 Subtype Cholinoceptor of Aged Rats

目的：观察老年大鼠不同脑区胆碱能Ｍ１亚型受体的变化和黄芪对其的调节作用。方法：采用放射自显影技术显示大鼠脑Ｍ１受体，并用图像分析仪进行灰度分析，以反映Ｍ１受体在不同脑区的相对定量分布。结果：所得脑切片自显影灰度层次清晰，主要分布在大脑皮质、海马、纹状体部位，非特异结合灰度很低，老年大鼠皮质、海马、纹状体的灰度显著低于青年鼠，分别降低１５７８％，８６９％，１２３６％（Ｐ＜００５），老年服黄芪组三个部位的灰度均明显高于老年对照组，分别升高１６６３％，９８１％，１０３２％，（Ｐ＜００５）。结论：黄芪对老年大鼠降低的脑胆碱能Ｍ１亚型受体具有上调作用。

Objective: To study the change of brain M1 subtype cholinoceptor density in aged rats and the regulatory action of Astragalus membranaceus.Methods: An autoradiographic technique with 3 HPZ (pirizepine) as radioactive probe was used to study the change of M1 receptor density in brain slices.Results:It was found that the specific binding was mainly localized in cerebral cortex,hippocampus and striatum.The mean grey of the specific binding of the above three brain areas of aged rats,with the non-specific binding subtracted by using a computered image-analysis system,were significantly lower than those of young rats.The decrease was about 15.87% in cortex, 8.69% in hippocampus and 12.36% in striatum (P<0.05).Parallel experiments revealed that when aged rats were treated for 6 months by daily oral administration of Astragalus merbranaceus from 20 months old,the M1 subtype cholinoceptor densities of cortex,hyppocampus and striatum were significantly higher than untreated aged rats.The increase was about 16.63%,9.81%,10.32% respectively (P<0.05).Conclusion: Astragalus merbranaceus has an upregulatory effect on the M1 subtype cholinoceptor densities of cortex,hippocampus and striatum of aged rats.