iPLA2在人胰岛β细胞的表达和对胰岛素分泌功能的影响

Expression of iPLA2 in human pancreatic islets and its important role in glucose-stimulated insulin secretion

目的探讨Ca^2＋-非依赖性磷酸脂酶A2（iPLA2）在人胰岛的表达及在胰岛素分泌功能中的作用。方法正常人胰腺组织切片免疫组织化学染色及人胰岛Western印迹方法检测，观察iPLA2在人胰岛中的表达情况；随机分组对照研究iPLA2选择性抑制剂溴烯醇内酯（BEL）对离体人胰岛的葡萄糖刺激引起胰岛素分泌反应的影响。结果在人胰岛iPLA2高表达，与抗胰岛素染色分布一致，而外分泌腺很少表达；与对照组相比，BEL处理组胰岛素分泌反应明显减弱[（0．8285±0．0803）ng·胰岛^-1·h^-1，P〈0．01]，BEL通过抑制iPLA2活性抑制了葡萄糖刺激引起的离体人胰岛胰岛素分泌。结论iPLA2在人胰岛β细胞高表达并在葡萄糖刺激胰岛β细胞胰岛素分泌过程起到重要的作用。

Objective To assess the role of calcium-independent phospholipase A2 （ iPLA2 ） in human pancreatic islets. Methods The immunohistochemical analysis and Western blot were employed to examine iPLA2 expression in human pancreatic islets. Bromoenol lactone （ BEL）, a selective inhibitor of iPLA2, was used in a randomized controlled trial to compare its influence to glucose-stimulated insulin secretion. Results iPLA2 was expressed predominantly in islet ceils co-stained by insulin but was barely detected in the exocrine acinar cells. Western blot results indicated that islet cells expressed an iPLA2- immunoreactive band at the 80 000 region. Glucose-stimulated insulin secretory response was dramatically reduced in islets pretreated with BEL （0. 8285 ± 0. 0803 ng· islet- 1· h - 1 ） as compared with the control （ 1. 2264 ±0. 0568 ng · islet^-1· h^-1 ） （p 〈0. 01 ）. BEL inhibited glucose stimulated insulin secretion from isolated human islets. Conclusion iPLA2 signaling plays an important role in glucose-stimulated insulin secretion under the physiological conditions.