Antioxidant effect of metformin in a murine model of hyperandrogenized pregnancy

Abstract

The aim of this work was to study the effects of metformin (M) on the nitric oxide system and the redox balance in a murine model of hyperandrogenized early pregnancy. Hyperandrogenization is a main clinical feature of polycystic ovary syndrome (PCOS). The biguanide M is a non-hormonal treatment used in PCOS, even during pregnancy, but its mechanism of action is not completely known. The experimental model used here involves early pregnant Balb/c mice hyperandrogenized by dehydroepiandrosterone (DHEA) and treated orally with metformin. We determined the nitric oxide synthases expression, nitric oxide production and redox parameters such as glutathione, superoxide dismutase, catalase and lipid peroxidation in implantation sites. We found that DHEA triggered an increase in the expression of iNOS and eNOS measured by immunohistochemistry and also in NO detected by the Griess method (p<0.001 in all cases), whereas in the group treated with DHEA and metformin (DHEA+M) it was similar to control. DHEA enhanced oxidative stress in uterine homogenates: lipid peroxidation measured by TBA-RS (p<0.01) and the content of the antioxidant metabolite glutathione detected by Tietze method (p<0.01). Lipid peroxidation was similar to control in DHEA+M, whereas glutathione was similar to DHEA group. The activities of the antioxidant enzymes superoxide dismutase and catalase did not show significant differences. We conclude that M avoids the effects of DHEA in implantation sites of DHEA - hyperandrogenized early pregnant Balb/c mice: oxidative stress and enhancement in the NO system.La hiperandrogenización es una de las características clínicas principales del síndrome de ovario poliquístico (SOP). La metformina (M) es un tratamiento no hormonal utilizado en el SOP incluso durante el embarazo. El objetivo fue estudiar los efectos de M sobre el balance redox y el sistema óxido nítrico (ON) en un modelo murino de preñez temprana hiperandrogenizada. Se utilizaron ratones Balb/ c hiperandrogenizados por dehidroepiandrosterona (DHEA) durante la preñez temprana y tratados oralmente con M. Se determinaron parámetros redox y del sistema ON en los sitios de implantación. La DHEA incrementó el estrés oxidativo: peroxidación lipídica (TBA-RS; p <0.01) y glutatión (Tietze; p <0.01). Con DHEA+M, TBA-RS fue similar al control y el glutatión fue similar al grupo DHEA. Las enzimas superóxido dismutasa y catalasa no mostraron diferencias. La DHEA provocó un aumento en la expresión de óxido nítrico sintetasa inducible (ONSi) y óxido nítrico sintetasa endotelial (ONSe) (inmunohistoquímica) y en ON (Griess; p <0,001 en todos los casos). Con DHEA+M fueron similares al control. Concluimos que M evita los efectos de DHEA sobre el estrés oxidativo y el sistema ON en los sitios de implantación de ratones Balb/ c durante la preñez temprana hiperandrogenizada.