吗啡依赖大鼠胃肠多巴胺递质和D2受体的改变

Changes of dopamine content and D2 receptor expression in gastrointestinal tissues of morphine-dependent rats

目的:探讨吗啡依赖胃肠损伤的多巴胺(dopamine,DA)能作用机制.方法:吗啡剂量递增皮下注射训练10 d,建立大鼠吗啡条件性位置偏爱(conditioned place preference,CPP)模型,生理盐水对照组(normal saline,NS)组和吗啡模型组(模型组)各取10只断头处死,取胃和十二指肠黏膜,荧光分光光度法检测其DA含量;另再取10只,采用Western blot检测其胃(胃贲门、胃体和幽门)和十二指肠组织多巴胺受体亚型2(dopamine D2 receptor,D2R)蛋白的表达.两组计量资料比较采用t检验.结果:模型组大鼠胃、十二指肠D A含量(18.41 n g/g±0.62 n g/g、9.01 n g/g±2.37ng/g)较NS组(32.01 ng/g±0.61 ng/g、17.31ng/g±2.58 ng/g)显著减少(胃:t=49.765,P=0.000;十二指肠:t=7.485,P=0.000);而模型组胃贲门、胃体和十二指肠的D2R平均光密度值(0.67±0.05、0.53±0.08和0.61±0.07)较NS组(0.43±0.08、0.33±0.07和0.44±0.05)明显升高(胃贲门:t=7.557,P=0.001;胃体:t=6.859,P=0.000;十二指肠:t=6.188,P=0.001);胃幽门变化差异无统计学意义(t=0.84,P=0.43).结论:吗啡依赖胃肠的损伤与胃肠DA系统的改变(递质和D2R受体)具有一定的相关性.

AIM： To investigate the mechanism of action of dopamine in gastrointestinal injury in morphine-dependent rats.METHODS： A conditioned place preference（CPP） model was established by injecting rats with increasing doses of morphine. The rats were divided into two groups： a model group（M） and a saline group（N）. Ten rats in each group were killed to detect the DA contents in the stomach and duodenum with a fluorescence spectrophotometer. The other 10 rats were used to test the expression levels of D2 receptor in the gastric cardia, body, pylorus and duodenum by Western blot. RESULTS： The expression of DA in the stomach and duodenum was significantly lower in the model group than in the control group（18.41 ng/g ± 0.62 ng/g vs 32.01 ng/g ± 0.61 ng/g, 9.01 ng/g ± 2.37 ng/g vs 17.31 ng/g ± 2.58 ng/g, P〈0.01）. The expression of D2 R in the gastric cardia, gastric body and duodenum was significantly higher in the morphine dependent group than in the control group（0.67 ± 0.05 vs 0.43 ± 0.08, 0.53 ± 0.08 vs 0.33 ± 0.07, 0.61 ± 0.07 vs 0.44 ± 0.05, P〈0.01）. CONCLUSION：There is an obvious link between the pathological injury in gastrointestinal tissue and the DA system change in morphine-dependent rats.