Dual effect of advanced glycation end products in pancreatic islet apoptosis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Background Loss of -cell function hastens deterioration of metabolic control in type 2 diabetes patients. Besides amyloid deposit and glucolipotoxicity, advanced glycation end products (AGEs) acting through their receptors (RAGE) seem to contribute to this process by promoting islet apoptosis. In order to investigate the role of AGEs in -cell deterioration, we evaluated the temporal and dose effects of AGE compounds on apoptosis rate, reactive oxygen species generation and expression of pro-apoptotic and anti-apoptotic genes in cultured islets. Methods Rat pancreatic islets were exposed or not for 24, 48, 72 and 96h to albumin modified by glycoaldehyde. Apoptosis, reactive oxygen species and superoxide content and NADPH oxidase activity were evaluated as well as RNA expression of the genes Ager (codes for RAGE), Bax, Bcl2 and Nfkb1. Results In 24 and 48h, glycoaldehyde elicited a decrease in apoptosis rate in comparison with the control condition concomitantly with a reduction in Bax/Bcl2 RNA ratio and in Nfkb1 RNA expression. In contrast, after 72 and 96h, glycoaldehyde promoted an increase in apoptosis rate concomitantly with an increase in Bax/Bcl2 RNA ratio and in Nfkb1 RNA expression. In 24h, glycoaldehyde elicited a decrease in the islet content of reactive oxygen species, whereas after 48 and 72h, it promoted an opposite effect, increasing superoxide generation. The NADPH oxidase inhibitor VAS2870 attenuated superoxide production, implicating NADPH oxidase as an important source of reactive oxygen species in islets exposed to AGEs. Conclusions Albumin modified by glycoaldehyde exerted a dual effect in cultured pancreatic islets, being protective against apoptosis after short exposure but pro-apoptotic after prolonged exposure. Copyright (c) 2013 John Wiley & Sons, Ltd.294296307Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [07/53870-1