大蒜素对链脲佐菌素所致糖尿病大鼠胰岛的保护作用

摘要

Objective To investigate the prote ctive effects of allicin (diallyl thiosulfinate) on islet tissue in diabetic rats induced by streptozotocin (STZ). Methods A hundred diabetic rat models induced by intraperitoneal injecting STZ were randomly devided into five groups:diabetic model control group, allicin(5,10 and 20 mg/kg) treated groups and metformin hydrochloride 200 mg/kg treated group. Another 20 same-aged rats were used as normal group. Each week before and after the drug was given, the levels of blood sugar and insulin were determined. Four weeks later, the histopathological changes in pancreatic tissue and islet cells apoptosis were observed, and the apoptosis index (AI) was analyzed; the level of T-AOC and the content of MDA in serum were determined; the activities of SOD, GSH-Px, CAT in pancreatic tissue were also determined. Results Compared with the diabetic model control group, the levels of insulin in allicin 10, 20 mg/kg treated groups were significantly increased and the blood sugar level was significantly decreased (P<0.05, P<0.01); the pancreatic tissue histopathological changes and islet cells apoptosis were obviously improved, the AI was significantly decreased (P<0.01); the content of MDA in serum was significantly decreased; the activities of SOD and CAT in pancreatic tissue were significantly increased(P<0.05, P<0.01). The level of T-AOC in allicin 20 mg/kg treated group was significantly increased (P<0.05), and the activity of GSH-PX in pancreatic tissue was significantly increased (P<0.05). Compared with Metformin hydrochloride 200 mg/kg treated group, the level of insulin in allicin 20 mg/kg treated groups was significantly increased (P<0.05), the level of T-AOC in serum was significantly increased (P<0.05), the activity of SOD, GSH-Px,CAT in pancreatic tissue were also significantly increased (P<0.05, P<0.01). Conclusion Allicin could effectively improve insulin secretion, lower blood sugar, depress the pancreatic tissue histopathological changes and islet cells apoptosis, suggesting that allicin has dose-dependent protective effects on islet tissue in diabetic rats induced by STZ, which is perhaps related to its effects of improving antioxidant ability and inhibiting the oxidative stress.%目的 研究大蒜素(diallyl thiosulfinate, allicin)对链脲佐菌素(streptozotocin,STZ)所致糖尿病大鼠胰岛的保护作用.方法 实验用SD大鼠经高脂高糖饲料喂养8周后,通过腹腔注射STZ的方法诱导糖尿病大鼠模型,选取100只随机分为:糖尿病模型组、大蒜素(5、10和20 mg/kg)治疗组和盐酸二甲双胍(200 mg/kg)治疗组,每组20只,并另设正常对照组.大蒜素各治疗组通过腹腔注射给药,盐酸二甲双胍治疗组灌胃给药,正常对照组和糖尿病模型对照组腹腔注射给予等体积的生理盐水,每天1次,疗程4周. 分别于给药前和给药后每周测定各组大鼠空腹血糖和胰岛素水平;4周后,通过HE染色观察胰腺组织病变;通过TUNEL染色观察胰岛细胞凋亡并计算凋亡指数(apoptosis index, AI);测定血清中总抗氧化能力(T-AOC)水平和丙二醛(MDA)含量;测定胰腺组织中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-PX)、过氧化氢酶(CAT)活性. 结果 与糖尿病模型组比较,大蒜素治疗组大鼠胰腺组织病变程度和胰岛细胞凋亡状况明显得到改善,其中大蒜素10、20 mg/kg治疗组大鼠胰岛细胞AI指数明显降低(P<0.01)、大鼠空腹血糖水平显著降低、胰岛素水平显著升高(P<0.05,P<0.01)、血清中MDA含量显著降低、胰腺组织中SOD、CAT活性显著升高(P<0.05,P<0.01),大蒜素20 mg/kg治疗组大鼠血清中T-AOC水平显著升高、胰腺组织中GSH-PX活性显著升高(P<0.05);大蒜素20 mg/kg治疗组,较盐酸二甲双胍治疗组大鼠胰岛素水平显著升高、血清中T-AOC水平显著升高、胰腺组织中SOD、GSH-Px和CAT活性显著升高(P<0.05,P<0.01). 结论 大蒜素能有效提高胰岛素分泌、降低血糖、改善胰腺组织病变并抑制胰岛细胞凋亡,提示大蒜素对STZ素所致糖尿病大鼠胰岛具有剂量依赖性的保护作用,其作用机制可能与大蒜素能有效改善抗氧化酶活性、提高自由基清除能力、抑制氧化应激损伤有关.