泛素-蛋白酶体抑制剂MG132对糖尿病大鼠视网膜上Smad7表达的影响

Effects of ubiquitin-proteasome inhibitor MG132 on expression of Smad7 in retina of rats with diabetes mellitus

目的探讨泛素-蛋白酶体抑制剂MG132对链脲佐菌素(streptozotocin,STZ)诱导的糖尿病(diabetes mellitus,DM)大鼠模型视网膜上Smad7表达的影响,研究Smad7的表达与糖尿病视网膜病变(diabetic retinopathy,DR)的关系,为预防及早期治疗DR提供一种新思路。方法选择60只健康的雄性Wistar大鼠随机分为3组:正常对照组、DM+MG132组和DM组。采用一次性腹腔注射50mg.kg-1STZ的方法建立DM大鼠模型。自DM模型建立后第3天起,DM+MG132组大鼠每天给予0.1mg.kg-1MG132DMSO液腹腔注射,正常对照组和DM组每天给予0.1mg.kg-1DMSO液腹腔注射。于造模后8周和12周时处死各组大鼠,然后摘出眼球,制成眼杯,采用免疫组化的方法检测各组大鼠视网膜上Smad7蛋白的表达。各指标均采用均数±标准差表示,多组间均数比较采用单因素方差分析,组间的多重比较采用q检验法,以P<0.05为差异有统计学意义。结果在正常对照组大鼠视网膜上Smad7蛋白高表达;DM组造模后8周和12周时大鼠视网膜上Smad7的光密度(optical densi-ty,OD)值分别是0.3408±0.0007、0.1193±0.0028,明显低于正常对照组(分别为0.8793±0.0015和0.9605±0.0021)(均为P<0.01);DM+MG132组造模后8周和12周时大鼠视网膜上Smad7的OD值分别是0.4864±0.0015、0.5904±0.0122,亦明显低于正常对照组(均为P<0.01);DM+MG132组造模后8周和12周时大鼠视网膜上Smad7的表达较DM组明显增加(均为P<0.01)。结论泛素-蛋白酶体抑制剂MG132能够有效抑制Smad7的表达,对DM大鼠视网膜具有保护作用,因此有望成为DR的新的治疗手段。

Objective To investigate the effects of ubiquitin-proteasome inhibitor MG132 on Smad7 expression in the retina of rats with diabetes mellitus（DM） induced by streptozotocin,then further study the relationship of Smad7 and diabetic retinopathy （DR）, and provide a new way for prevention and early treatment of DR. Methods Sixty male Wistar rats were divided into three groups randomly： Normal control group, DM ＋ MG132 group and DM group. DM model was established by intraperitoneal injec- tion ofS0 mg · kg-1 STZ. 0. 1 mg· kg-1 of MG132 DMSO was intraperitoneal injected once per day in DM ＋ MG132 group and the same volume of DMSO was intraperitoneal injected once per day in normal control group and DM group after modeling 3 days. At 8 weeks and 12 weeks, the rats were sacrificed and removed eyeballs to make the eye cups. Smad7 protein expression was detected by immunohistochemistry in the retina. The results were showed by means plus or subtracting standard, the groups means was compared by ONE-WAY AONVA,the deviation of between groups means was compared by Student-Newman-Keuls. Results The Smad7 was expressed highly in rat retina of normal control group. The value of average optical density （OD） of Smad7 at 8 weeks and 12 weeks were 0. 340 8 ±0.000 7 and 0. 119 3 ±0.002 8 in rat retina of DM group,which were lower than those of normal control group （0. 879 3 ± 0.001 5 and 0. 960 5 ± 0. 002 1 ）,there were significant differences（both P 〈0.01 ）. The value of OD of Smad7 at 8 weeks and 12 weeks were 0. 486 4 ± 0.001 5 and 0. 590 4 ± 0.012 2 in rat retina of DM ＋ MG132 group, which were lower than those of normal control group, there were significant differences（ both P 〈0.01 ）. The expression of Smad7 was significantly elevated in DM ＋ MG132 group compared with DM group at 8 weeks and 12 weeks, there were significant differences （ both P 〈 0.01 ）. Conclusion The expression of Smad7 was effectively inhibited by MG132. MG132 is expected to become one of the new therapeutic methods because it has protective retina role in rat with DR.