多巴胺受体在大鼠结肠黏膜下神经丛的表达和细胞分布

摘要

Objective Dopamine (DA) plays an important role in the regulation of intestinal motility,secretion and mucosal barrier by binding to its receptors.It has been shown that submucosal neurons are involved in the regulation effect of DA on the mucosa function.However the expressions of DA receptors in submucosal neurons are not clear.The aim of the present study is to investigate the distribution of DA receptors in vasoactive intestinal peptide (VIP) neurons and cholinergic neurons in the submucosa.Methods The mRNA and protein expression of DA receptors was measured by RT-PCR and Western blotting.Immunofluorescent double labeling of DA receptors with submucosal VIP neurons and cholinergic neurons were observed under confocal laser scanning microscope.Results Both the mRNA and protein of DA receptors D1,D2 and D5 were expressed in the colonic submucosal layer.In the submucosal plexus,D1 positive VIP-positive neurons accounting for 58.94％ ± 2.245％,D2 for 52.03％ ± 9.384％,and D5 for 86.21％ ± 2.902％.The number of D5 positive neurons was significantly higher than that of D1 and D2.In the submucosal plexus,D1 positive cholinergic neurons accounted for 87.75％ ±7.307％,D2 for 88.50％ ±8.761％,and D5 for 89.25％ ± 10.75％,and the distribution of the three types of DA receptors in the cholinergic neurons had no significant difference.Conclusion DA receptors D1,D2 and D5 are expressed in the submucosal layer of the rat colon.And they all are distributed in the submucosal VIP and cholinergic neurons,and D5 expression was higher than D1 and D2 in VIP-positive neurons.Our study provides a morphological basis for the regulation of DA on the colonic mucosal function.%目的 多巴胺(dopamine,DA)与其受体结合调节肠道动力、黏膜分泌及屏障等,黏膜下神经元参与DA对黏膜的生理调节,但其受体的具体分布尚不明了.通过检测DA受体在大鼠结肠黏膜下层的蛋白和mRNA表达及细胞分布,为DA调节大鼠结肠病理生理机制提供依据.方法 用RT-PCR和Western blotting方法定性测定DA受体在大鼠结肠黏膜下层的mRNA和蛋白的表达;免疫荧光双染色后在激光共聚焦显微镜下观察DA受体在黏膜下血管活性肠肽(vasoactive intestinal peptide,VIP)能和胆碱能神经元上的分布.结果 在大鼠结肠黏膜下层,DA受体D1、D2、D5的mRNA及蛋白均有表达;在黏膜下神经丛VIP能阳性的神经元中有大量分布,其中D1阳性的神经元占58.94％±2.245％,D2阳性神经元占52.03％±9.384％,D5阳性神经元占86.21％±2.902％,且D5阳性神经元数量显著高于D1和D2;在黏膜下神经丛胆碱能阳性的神经元广泛表达DA受体,其中D1阳性神经元占87.75％ ±7.307％,D2阳性神经元占88.50％±8.761％,D5阳性神经元占89.25％±10.75％.结论 DA受体在大鼠结肠黏膜下层有D1、D2及D5的表达,且在VIP能及胆碱能神经元上均有分布,其中D5受体在VIP能神经元上的分布显著高于D1及D2受体.本研究可为深入探讨DA调节结肠黏膜生理及病理机制提供形态学依据.