他克莫司对大鼠肝脏组织蛋白磷酸酶2A和P-AKT表达的影响

目的 通过观察他克莫司对大鼠血糖、胰岛素水平、肝脏组织蛋白磷酸酶2A和磷酸化AKT表达的影响，进一步探究他克莫司导致血糖升高的机制。方法 将60只雄性SD大鼠（89.83?.44g）随机均分为他克莫司组和对照组，他克莫司组（n=40），每日空腹（禁食水8小时）灌胃给药，剂量为4mg/kg?d；对照组（n=20），每日空腹灌胃给予等量生理盐水，每月测量大鼠体重、空腹血糖, 5个月后处死大鼠，心脏穿刺取血，；取胰腺组织和肝脏组织，测大鼠血清胰岛素水平，行胰腺组织病理组织学观察，并对肝脏行组织处理和免疫组织化学技术检测肝细胞浆质中蛋白磷酸酶2A和磷酸化AKT的表达。结果 用药2个月后，他克莫司组大鼠的血糖水平明显高于对照组（P＜0.05），他克莫司组大鼠的胰岛素分泌指数、胰岛素敏感指数和均明显低于对照组（P＜0.05）；胰岛素抵抗指数明显增高（P＜0.05）。他克莫司组大鼠与对照组相比，其肝细胞浆质内PP2A表达明显增加，磷酸化的AKT表达明显减少。结论 他克莫司导致胰岛细胞坏死，胰岛细胞数量减少，胰岛素的分泌降低、胰岛素敏感性下降、胰岛素抵抗增加，从而导致大鼠血糖升高。他克莫司增加大鼠肝脏组织PP2A的表达，减少肝脏组织磷酸化的AKT的表达，可能通过PI3K/AKT信号转导途径参与胰岛细胞凋亡和胰岛素抵抗，引起血糖的升高。

Effects of tacrolimus on the expression of protein phosphatase 2A and P-AKT in rat hepatocytes

Objective To observe the effects of tacrolimus on blood glucose, insulin, expressions of protein phosphatase 2A and P-AKT in rats in order to explore the mechanism of hyperglycemic action of tacrolimus. Methods Sixty male SD rats (body weight 89.83±4.44 g) were randomly divided into tacrolimus group (n=40) and control group (n=20). The rats in the tacrolimus group were administrated with tacrolimus 4 mg/kg daily. The rats in the control group were given the same amount of normal drinking water daily. The rat body weight, fasting blood glucose concentration and blood concentration of tacrolimus were measured monthly. All rats were killed at 5 months after the tacrolimus administration. The serum insulin levels were detected by radioimmunoassay method. The expressions of PP2A and P-AKT in liver tissues were assessed by immunohistochemistry. Results After two months of administration, the blood glucose levels in the tacrolimus group were significantly higher than those in the control group. The HOMA-IR in tacrolimus group was significantly higher than that in the control group P < 0.05). ISI was significantly lower than that in the control group (P < 0.05). Immunohistochemical examination showed that the expression of PP2A in hepatocytes in the tacrolimus group was increased compared with the control group, while expression of P-AKT in hepatocytes of the tacrolimus group was decreased than that in the control group. Conclusions Tacrolimus can induce necrosis of islet cells, decrease of the amount of islet cells and insulin secretion, decease of sensitivity to insulin, and increase the resistance to insulin, therefore, leading to increase the blood glucose level in rats. The expression of PP2A in hepatocytes in the tacrolimus group is increased, while the expression of P-AKT is decreased. Interfering of insulin signal transduction pathways may be involved in the hyperglycemic effects of tacrolimus.