糖基化终末产物和磷酸化肌球蛋白轻链在糖尿病结肠动力障碍中的作用

Effects of Advanced Glycation End Products and Phosphorylated Myosin Light Chain on Diabetic Colonic Dysmotility

背景:结肠动力障碍是糖尿病(DM)的常见并发症。糖基化终末产物(AGEs)在DM患者体内显著升高,然而其在DM结肠动力障碍中的作用尚未完全明确。目的:探讨AGEs和磷酸化肌球蛋白轻链(p-MLC)在DM结肠动力障碍中的作用。方法:将Sprague-Dawley大鼠随机分为DM组和正常对照组,以链脲菌素腹腔注射建立DM模型,8周后处死所有大鼠,取远端结肠组织。检测离体结肠肌条肌张力;以免疫组化染色检测结肠组织p-MLC表达;以蛋白质印迹法检测结肠组织p-MLC、总肌球蛋白轻链(t-MLC)表达。分离培养结肠平滑肌细胞(SMCs),以不同浓度、不同作用时间AGEs作用于SMCs,以蛋白质印迹法检测SMCs的p-MLC、t-MLC表达。结果:与正常对照组相比,DM组大鼠结肠平滑肌张力显著减弱[(0.89±0.09)g对(1.98±0.12)g,P<0.05],DM组大鼠结肠组织pMLC/t-MLC/β-actin水平显著降低(0.98±0.10对1.61±0.12,P<0.05)。SMCs经不同浓度、不同作用时间AGEs干预后,p-MLC/t-MLC/β-actin水平显著降低。结论:DM结肠动力障碍可能由AGEs抑制SMCs中MLC磷酸化所致。

Colonic dysmotility is a common complication of diabetes mellitus （DM）. Advanced glycation end products （AGEs） is significantly increased in patients with DM, however, its effect on diabetic colonic dysmotility has not yet been fully clarified. Aims ： To investigate the effects of AGEs and phosphorylated myosin light chain （ p-MLC ） on diabetic colonic dysmotility. Methods： Sprague-Dawley rats were randomly divided into DM group and normal control group. DM model was established by intraperitoneal injection of streptozotocin. Rat were sacrificed 8 weeks later and specimens of distal colon were obtained. The contraction ability of colonic smooth muscle was assessed, and expression of p-MLC in colonic tissue was determined by immunohistoehemistry ; expressions of p-MLC and total myosin light chain （ t- MLC） were determined by Western blotting. Colonic smooth muscle cells （SMCs） were isolated and treated with different concentrations and different time durations of AGEs. Expressions of p-MLC and t-MLC in SMCs were determined by Western blotting. Results： Muscle tonus of colonic smooth muscle was significantly weaker in DM group than that in normal control group [ （0.89 _＋ 0.09 ） g vs. （ 1.98 ＋ 0.12） g, P 〈 0.05 ]. Expression of p-MLC/t-MLC/13-aetin was significantly decreased in colonic tissue in DM group than that in normal control group （0.98 ± 0.10 vs. 1.61 ± 0. 12, P 〈 0.05 ）. Expression of p-MLC/t-MLC/13-actin was significantly decreased in SMCs treated with different concentrations and different time durations of AGEs. Conclusions： AGEs can inhibit phosphorylation of MLC in SMCs, which may lead to colonic dysmotility in DM.