AMPK/SIRT1/PGC-1α/SIRT3 pathway - independent activation of GPx1 expression by metformin in the heart of a mouse model of endometriosis

Abstract

Endometriosis is a gynecological disease associated with an imbalance between oxidative species production and anti-oxidative defenses. In women, a correlation has been reported between endometriosis and incidence of cardiovascular events. As such, this study aimed to analyze the oxidation-responsive AMPK/SIRT1/PGC-1α/SIRT3 pathway in the heart of a mouse model of endometriosis. The effect of metformin, an insulin-sensitizing and anti-oxidative drug with already shown positive results in endometriotic tissue was also studied. Thirty-six female B6CBA/F1 mice were divided into 4 groups (Control-C, Surgery-induced Endometriosis and Metformin-EM (50 mg/Kg/day orally administrated for 3 months), Endometriosis-E and Metformin-M). Immunofluorescent labelling of SIRT1 and SIRT3 was performed in heart tissue. Assessment of expression of AMPKα, SIRT1, PGC-1α, SIRT3, SOD2, and GPx1 was carried out by Western Blotting. The quantification of microRNA(miR)-34a, miR-195, miR-217, miR-155 and miR-421, involved in the regulation of expression of SIRT1 and SIRT3, was performed by Real-Time PCR. Data showed an increase in phospho-AMPKα and in GPx1 expression in the EM group when compared to the C group, but not in the total AMPK, SIRT1, PGC-1α, SIRT3 and SOD2, suggesting a GPx1 expression increase independently of the AMPK/SIRT1/PGC-1α/SIRT3 pathway. MicroRNAs, excepting miR-217, showed a consistent trend of increase in the M group. Collectively, our study showed that endometriosis does not significantly affect the expression of the components of the AMPK/SIRT1/PGC-1α/SIRT3 pathway in the heart. However, it indicates that an oxidative condition underlying endometriosis is required for metformin to evidence a beneficial antioxidant effect by increasing the expression of the anti-oxidative enzyme GPx1.