多巴胺受体在大鼠胃和十二指肠的定位及表达

Localization and expression of dopamine receptors in stomach and duodenum in rats

通过定量原位杂交技术，检测胃十二指肠中是否存在多巴胺受体，以及多巴胺５个亚型受体的定位和表达情况。方法参照文献选定核苷酸序列、制备寡核苷酸探针，并以末端脱氧核苷转移酶末端标记３５Ｓ，然后与新鲜冰冻组织胺Ｙｏｕｎｇ方法行原位杂交、曝光、显影。银粒密度由电子图象分析系统计数并行统计学处理。结果多巴胺５个亚型受体均存在于胃肠道，但表达水平高低不一；多巴胺受体分布于胃的粘膜固有层，沿粘膜肌层分布，而十二指肠的多巴胺受体则弥散分布于粘膜固有层及绒毛间质内。结论胃肠道多巴胺通过受体发挥作用；在５个亚型受体中，介导胃肠道生理功能者主要是Ｄ５亚型，Ｄ４受体可能起调节作用。

Dopamine is an important neurotransmitter which may contribute to the regulation of gastrointestinal function,but its mechanism remains elusive.Objective The existence, localization and expression of dopamine receptor mRNAs in rat stomach and duodenum were examined by in situ hybridization.Methods The oligonucleotide probes were selected and synthesized according to the previous work.All the probes were labelled with alphaS35dATP using the terminal deoxynucleotide transferase,then were hybridized with the frozen,fixed preparation of rat stomach and duodenum.The density of silver granules were counted and analyzed by the image analysis computer system.Results It was found that all five subtypes of dopamine receptor mRNAs existed in the stomach and duodenum with greatly different expression.The distribution of dopamine mRNAs in the stomach were mainly localized in the lamina propria near the lamina muscularis mucosae and parallel to the longitudinal axis of the tract.Whereas,all five mRNAs were spread over the entire layer of the duodenal mucosa. With the image analysis system, abundant expressing levels of D 5 and D 4 mRNAs were documented unexpectedly. Conclusion All these results suggest that dopamine produced its effect via dopamine receptors especially D 5 subtype and D 4 receptor might be act as a modulator.