氯沙坦对血管紧张素Ⅱ损伤RIN-m细胞胰岛素分泌功能的保护及机制探讨

Protective effect of losartan on insulin secretion function of RIN-m cells against angiotensin II-induced injury and the mechanism

目的观察氯沙坦对血管紧张素Ⅱ(AngⅡ)损伤β细胞(RIN-m)功能的保护,并对其机制进行探讨。方法常规培养RIN-m细胞,分为空白对照组、100nmol/LAngⅡ组和氯沙坦预处理组,各组干预24h后使用放射免疫法检测基础(3.3mmol/L)和葡萄糖(16.7mmol/L)刺激下RIN-m细胞胰岛素分泌量;DCFH-DA染色流式细胞仪检测细胞内活性氧(ROS)水平;RT-PCR和Western blotting分别检测RIN-m细胞解偶联蛋白2(UCP2)mRNA和蛋白的表达。结果①各组基础胰岛分泌没有显著差异(P>0.05),在高糖刺激下,100nmol/LAngⅡ组胰岛素分泌量明显低于空白对照组(P<0.001),氯沙坦预处理组胰岛素分泌量与空白对照组无显著差异(P>0.05),但较AngⅡ组明显增加(P<0.001);②100nmol/LAngⅡ组细胞内ROS水平、UCP2mRNA和蛋白表达均较空白对照组明显增加(P<0.001),氯沙坦预处理组与空白对照组无显著差异(P>0.05),但较100nmol/LAngⅡ组显著降低(P<0.001)。结论AngⅡ损伤β细胞葡萄糖刺激胰岛素分泌(GSIS)功能,氯沙坦预处理可以拮抗AngⅡ的作用,减少β细胞内ROS水平,下调UCP2表达,最终对β细胞起到保护作用。

Objective To investigate the protective effect of losartan against angiotensin II （AngII）-induced β cell （RIN-m） impairment and explore its mechanism. Methods In vitro cultured RIN-m cells were divided into control group, 100 nmol/L AngII group and losartan pretreatment group. After cell incubation with the corresponding agents for 24 h, the amount of basal （3.3 mmol/L） and glucose-stimulated （16.7 mmol/L） insulin secretion （GSIS） was detected by radioimmunoassay, and the cellular reactive oxygen species （ROS） was assayed by flow cytometry with DCFH-DA staining; the mRNA and protein expressions of uncoupling protein 2 （UCP2） were determined by RT-PCR and Western blotting, respectively. Results The basal insulin secretion showed no significant differences between the 3 groups （P0.05）. The GSIS in 100 nmol/L AngII group was significantly lower than that of the control group （P0.001）, but losartan pretreatment markedly restored the insulin secretion function to a level comparable to that of the control group （P0.05）. Compared with the control group, 100 nmol/L AngII significantly increased the cellular ROS level and the mRNA and protein expressions of UCP2 （P0.05）, and these changes were eliminated by losartan pretreatment. Conclusions Losartan pretreatment offers protective effect against AngII-induced impairment of the GSIS of β cells possibly by antagonizing the effects of AngII that causes increased ROS level and UCP2 expressions in β-cells.