Selective Serotonin Reuptake Inhibitors (SSRIs) Inhibit Insulin Secretion and Action in Pancreatic Beta Cells
OPEN The Journal of biological chemistry | 1 Jan 2013
R Isaac, S Boura-Halfon, D Gurevitch, A Shainskaya, Y Levkovitz and Y Zick
Selective serotonin reuptake inhibitors (SSRIs) are antidepressants used for the treatment of mood and anxiety disorders. Here we demonstrate that incubation (2 h) of murine islets or Min6 β cell line with the SSRIs paroxetine, fluoxetine or sertraline inhibited insulin-induced Tyr phosphorylation of insulin receptor substrate (IRS)-2 protein and the activation of its downstream targets Akt and S6K1. Inhibition was dose-dependent with half-maximal effects at ~15-20 μM. It correlated with a rapid phosphorylation and activation of the IRS kinase GSK3β. Introduction of GSK3β-siRNAs eliminated the inhibitory effects of the SSRIs. Inhibition of IRS-2 action by 30 μM SSRIs was associated with a marked inhibition of glucose-stimulated insulin secretion from murine and human pancreatic islets. Secretion induced by basic secretagogues (KCl and Arg) was not affected by these drugs. Prolonged treatment (16h) of Min6 cells with sertraline resulted in the induction of iNOS; activation of an ER stress and the initiation of the Unfolded Protein Response (UPR), manifested by enhanced transcription of ATF4 and CHOP. This triggered an apoptotic process, manifested by enhanced caspase 3/7 activity, that resulted in beta cell death. These findings implicate SSRIs as inhibitors of IRS protein function and insulin action through the activation of GSK3β. They further suggest that SSRIs inhibit insulin secretion; induce the UPR; activate an apoptotic process and trigger beta cell death. Given that SSRIs promote insulin resistance while inhibiting insulin secretion, these drugs might accelerate the transition from an insulin resistant state to overt diabetes.
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