Institute of Pharmacology, Toxicology and Clinical Pharmacy, Technische Universität Braunschweig, D-38106, Braunschweig, Germany.
Institute of Medicinal and Pharmaceutical Chemistry, Technische Universität Braunschweig, D-38106, Braunschweig, Germany.
Naunyn Schmiedebergs Arch Pharmacol. 2021 Jun;394(6):1133-1142. doi: 10.1007/s00210-020-02046-2. Epub 2021 Jan 19.
Apparently, both a decrease in beta cell function and in beta cell mass contribute to the progressive worsening of type 2 diabetes. So, it is of particular interest to define factors which are relevant for the regulation of insulin secretion and at the same time for the maintenance of beta cell mass. The NADPH-thioredoxin system has a candidate role for such a dual function. Here, we have characterized the effects of a highly specific inhibitor of thioredoxin reductase, AM12, on the viability and function of insulin-secreting MIN6 cells and isolated NMRI mouse islets. Viability was checked by MTT testing and the fluorescent live-dead assay. Apoptosis was assessed by annexin V assay. Insulin secretion of perifused islets was measured by ELISA. The cytosolic Ca concentration was measured by the Fura technique. Acute exposure of perifused pancreatic islets to 5 μM AM12 was without significant effect on insulin secretion. Islets cultured for 24 h in 0.5 or 5 μM AM12 showed unchanged basal secretion during perifusion, but the response to 30 mM glucose was significantly enhanced by 5 μM. Twenty-four-hour exposure to 5 μM AM12 proved to be without effect on the viability of MIN6 cells, whereas longer exposure was clearly toxic. Islets were more susceptible, showing initial signs of apoptosis after 24-h exposure to 5 μM AM12. The activity of the NADPH-thioredoxin system is indispensable for beta cell viability but may have a limiting effect on glucose-induced insulin secretion.
显然，β细胞功能下降和β细胞数量减少都导致 2 型糖尿病逐渐恶化。因此，确定与胰岛素分泌调节有关且同时与β细胞数量维持有关的因素具有特别的意义。NADPH-硫氧还蛋白系统可能具有这种双重功能的候选作用。在这里，我们描述了一种高度特异性的硫氧还蛋白还原酶抑制剂 AM12 对胰岛素分泌 MIN6 细胞和分离的 NMRI 胰岛的活力和功能的影响。通过 MTT 检测和荧光死活检测来检查活力。通过 Annexin V 测定法评估细胞凋亡。通过 ELISA 测量灌流胰岛的胰岛素分泌。通过 Fura 技术测量胞质 Ca 浓度。急性暴露于 5 μM AM12 的灌流胰岛对胰岛素分泌没有显著影响。在 0.5 或 5 μM AM12 中培养 24 小时的胰岛在灌流期间基础分泌保持不变，但对 30 mM 葡萄糖的反应明显增强。24 小时暴露于 5 μM AM12 对 MIN6 细胞的活力没有影响，而长时间暴露则明显有毒。胰岛更敏感，在 5 μM AM12 暴露 24 小时后出现凋亡的初始迹象。NADPH-硫氧还蛋白系统的活性对于β细胞活力是必不可少的，但可能对葡萄糖诱导的胰岛素分泌有一定的限制作用。
