锌原卟啉对糖尿病大鼠结肠动力及Cajal细胞的影响

Effects of zinc protoporphyrin on the colonic interstitial cells of Cajal and dysfunction in diabetic rats

目的探讨血红素氧合酶（HO）阻滞剂锌原卟啉（ZnPP）对糖尿病（DM）大鼠结肠动力和Cajal间质细胞（ICC）的影响。方法雄性SD大鼠腹腔注射链脲佐菌素（STZ），3d后选取成功造模大鼠24只作为DM组，另取正常大鼠16只作为对照组。饲养6周时，选取DM组大鼠和对照组大鼠各8只，行碳末推进实验，确认有无胃肠动力障碍。剩余DM组大鼠第6周起予以干预，DM未干预组（8只）0．1mol／L磷酸盐缓冲液腹腔注射，隔日1次，连续3周；DM＋ZnPP组（8只），ZnPP 10μmol／kg腹腔注射，隔日1次，连续3周。对照组（8只）予以膜腔注射0．1mmol／L磷酸盐缓冲液。Western印迹法检测结肠组织HO-1、HO-2和c-kit表达。免疫组化法测定结肠组织HO-1、HO-2和c—kit阳性细胞面积。结果DM未干预组胃肠推进指数为（63．0±1．2）％，较对照组显著减低[（71．8±2．0）％，P〈0．05]；而DM＋ZnPP组胃肠推进指数为（72．5±2．6）％，较DM未干预组明显改善（P〈0．05），且与对照组差异无统计学意义（P〉0．05）。DM＋ZnPP组近、远端结肠HO-1表达明显下降（P〈0．05）。DM未干预组和DM4-ZnPP组近端结肠HO-2表达均较对照组显著减少（P〈0．05）。DM未干预组近、远端结肠组织c-kit较对照组显著减少（P〈0．05）；DM＋ZnPP组c—kit的表达较DM未干预组明显改善（P〈0．05），且与对照组间差异无统计学意义（P〉0．05）。结论ZnPP可能通过阻滞HO-1对DM大鼠结肠Cajal间质细胞有保护作用，并改善其结肠动力障碍。

Objective To assess the effects of zinc protoporphyrin （ZnPP）, an inhibitor of the heme oxygenase （HO）, on the colonic interstitial cells of Cajal （ICC） of diabetic rats with colonic slow transit. Methods Diabetes mellitus （DM） model was induced by intraperitoneal injection of streptozotocin （STZ） in Sprague-Dawley rats. Twenty four successfully established DM rats were selected, and 16 healthy rats were served as controls. Six weeks later, gastrointestional （GI） dysfunction was observed by charcoal propulsion experiment in 8 DM rats and 8 controls. The rest rats in DM group were divided into 2 groups： DM rats intraperitoneal injected with PBS （n= 8） or with 10μmol/kg of ZnPP （n=8） every other day for 3 weeks. The rats in control group （n=8） were intraperitoneally injected with PBS. The levels of HO and c-kit （the special receptor of ICC） expression were detected by Western blotting. The distribution of ICC was observed by immunohistochemistry and the area of c-kit positive cells was counted. Results The GI propulsion rate in DM rats interfered with PBS was significantly declined compared to that in the controls （63.0±1.2 vs 71.8±2.0%, P〈0.05）. But it was improved in DM rats interfered with ZnPP （72.5±2.6%, P〈0.05）, which showed no significant differentce with that in control group （P〉0.05）. The expression of HO-1 in close and distant colon of DM rats interfered with ZnPP was decreased （P〈 0.05）. The expression of HO-2 in close colon and the area of c-kit positive cells of DM rats interfered with PBS was reduced compared with that in controls （P〈0.05）, but both were improved in DM rats interfered with ZnPP （P〈0.05）. Conclusion Administration of ZnPP might be able to protect ICC by its blockage of HO-1 in DM rats with gastrointestinal dysfunction.