氯化锌在低糖和高糖浓度下培养的大鼠胰岛中的保护抗氧化和抗细胞凋亡作用。

AIM/HYPOTHESIS: Rat pancreatic islet cell apoptosis is minimal after prolonged culture in 10 mmol/l glucose (G10), largely increased in 5 mmol/l glucose (G5) and moderately increased in 30 mmol/l glucose (G30). This glucose-dependent asymmetric V-shaped profile is preceded by parallel changes in the mRNA levels of oxidative stress-response genes like Metallothionein 1a (Mt1a). In this study, we tested the effect of ZnCl(2), a potent inducer of Mt1a, on apoptosis, mitochondrial oxidative stress and alterations of glucose-induced insulin secretion (GSIS) induced by prolonged exposure to low and high vs. intermediate glucose concentrations. METHODS: Male Wistar rat islets were cultured in RPMI medium. Islet gene mRNA levels were measured by RTq-PCR. Apoptosis was quantified by measuring islet cytosolic histone-associated DNA fragments and the percentage of TUNEL-positive β-cells. Mitochondrial thiol oxidation was measured in rat islet cell clusters expressing "redox sensitive GFP" targeted to the mitochondria (mt-roGFP1). Insulin secretion was measured by RIA. RESULTS: As observed for Mt1a mRNA levels, β-cell apoptosis and loss of GSIS, culture in either G5 or G30 vs. G10 significantly increased mt-roGFP1 oxidation. While TPEN decreased Mt1a/2a mRNA induction by G5, addition of 50-100 µM ZnCl(2) to the culture medium strongly increased Mt1a/2a mRNA and protein levels, reduced early mt-roGFP oxidation and significantly decreased late β-cell apoptosis after prolonged culture in G5 or G30 vs. G10. It did not, however, prevent the loss of GSIS under these culture conditions. CONCLUSION: ZnCl(2) reduces mitochondrial oxidative stress and improves rat β-cell survival during culture in the presence of low and high vs. intermediate glucose concentrations without improving their acute GSIS.

目的/假设：在 10mmol/L 葡萄糖（G10）中长时间培养后，大鼠胰岛细胞凋亡很少，在 5mmol/L 葡萄糖（G5）中明显增加，在 30mmol/L 葡萄糖（G30）中中度增加。这种葡萄糖依赖性不对称 V 形分布先于氧化应激反应基因如 Metallothionein 1a（Mt1a）的 mRNA 水平的平行变化。在这项研究中，我们测试了 ZnCl2（一种强烈诱导 Mt1a 的物质）对凋亡、线粒体氧化应激和延长暴露于低、高与中间葡萄糖浓度下诱导的葡萄糖诱导胰岛素分泌（GSIS）的影响。

方法：雄性 Wistar 大鼠胰岛在 RPMI 培养基中培养。通过 RTq-PCR 测量胰岛基因的 mRNA 水平。通过测量胰岛细胞胞浆中与组蛋白相关的 DNA 片段和 TUNEL 阳性β细胞的百分比来量化细胞凋亡。使用靶向线粒体的“氧化还原敏感 GFP”（mt-roGFP1）表达的大鼠胰岛细胞簇测量线粒体硫醇氧化。通过 RIA 测量胰岛素分泌。

结果：与 Mt1a mRNA 水平一样，β细胞凋亡和 GSIS 丧失，与 G10 相比，在 G5 或 G30 中培养显著增加了 mt-roGFP1 的氧化。虽然 TPEN 降低了 G5 诱导的 Mt1a/2a mRNA 诱导，但在培养基中添加 50-100µM ZnCl2 强烈增加了 Mt1a/2a mRNA 和蛋白水平，减少了延长培养在 G5 或 G30 时早期的 mt-roGFP 氧化，并显著降低了晚期β细胞凋亡，与 G10 相比。然而，它并没有防止在这些培养条件下 GSIS 的丧失。

结论：ZnCl2 在存在低、高与中间葡萄糖浓度时减少线粒体氧化应激并改善大鼠β细胞的存活，而不改善其急性 GSIS。