Localization of acetylcholine receptor in Hirschsprung's disease

目前尚不清楚为什么巨结肠病的神经节结仍然受感染。我们对巨结肠病中乙酰胆碱酯酶活性的电镜研究显示该酶定位于外源性神经末梢和平滑肌细胞之间的间隙。我们的研究目的在于阐明乙酰胆碱受体是否存在于平滑肌细胞上接受外源性神经纤维的神经支配。方法：采用[3H]喹啉苄基苯甲酸酯放射自显像法研究正常大鼠和巨结肠大鼠肠内毒蕈碱乙酰胆碱受体的定位。结果：代表乙酰胆碱受体的银粒在正常大鼠粘膜和粘膜下层呈弥漫性分布，在肌层表面呈线性分布。在阿托品处理的大鼠中不识别颗粒，表明颗粒对毒蕈碱乙酰胆碱受体的特异性。在Hirschsprung大鼠的神经节结肠中也发现了毒蕈碱类乙酰胆碱受体。神经节结肠的银粒密度与正常结肠相差不大。结论：巨结肠大鼠神经节结肠与正常大鼠结肠一样存在毒蕈碱类乙酰胆碱受体。提示先天性巨结肠的神经节结平滑肌可能直接受增生的外源性神经支配。

It is not clearly defined why the aganglionic colon in Hirschsprung's disease remains contracted. Our electronmicroscopic study on acetylcholinesterase activity in Hirschsprung's disease revealed localization of the enzyme in the interspace between extrinsic nerve terminals and smooth muscle cells.Our research was aimed to clarify if the acetylcholine receptors exist on the smooth muscle cells to receive innervation of the extrinsic nerve fibers.Method: Localization of muscarinic acetylcholine receptors in the intestine of normal rats and Hirschsprung's rats was studied by autoradiography using [3H] quinuclidinyl benzilate.Results: Silver grains representing acetylcholine receptors were shown to distribute diffusely in the mucosa and submucosa, and linearly on the surface of muscular layers in normal rats. The grains were not recognized in the atropine-treated rats, indicating specificity of the grains to muscarinic acetylcholine receptors. Muscarinic acetycholine receptors were demonstrated also in the aganglionic colon of Hirschsprung's rats. The density of silver grains in the aganglionic colon did not differ much from that in the normal colon.Conclusions: Muscarinic acetylcholine receptors were present in the aganglionic colon of Hirschsprung's rat as in the normal rat colon. This finding indicates that smooth muscles of the aganglionic colon of Hirschsprung's disease may be directly innervated by the proliferated extrinsic nerves.