Insulin resistance is the decreased ability of insulin to mediate metabolic actions. In the ovary, insulin controls ovulation and oocyte quality. Alterations in ovarian insulin signaling pathway could compromise ovarian physiology. Here, we aimed to investigate the effects of fetal programming on ovarian insulin signaling and evaluate the effect of metformin treatment. Pregnant rats were hyperandrogenized with testosterone and female offspring born to those dams were employed; at adulthood, prenatally hyperandrogenized (PH) offspring presented two phenotypes: irregular ovulatory (PHiov) and anovulatory (PHanov). Half of each group was orally treated with metformin. Metformin treatment improved the estrous cyclicity in both PH groups. Both PH groups showed low mRNA levels of Ir, Irs1 and Glut4. Irs2 was decreased only in PHanov. Metformin upregulated the mRNA levels of some of the mediators studied. Protein expression of IR, IRS1/2 and GLUT4 was decreased in both PH groups. In PHiov, metformin restored the expression of all the mediators, whereas in PHanov, metformin restored only that of IR and IRS1/2. IRS1 phosphorylation was measured in tyrosine residues, which activates the pathway, and in serine residues, which impairs insulin action. PHiov presented high IRS1 phosphorylation on tyrosine and serine residues, whereas PHanov showed high serine phosphorylation and low tyrosine phosphorylation. Metformin treatment lowered serine phosphorylation only in PHanov rats. Our results suggest that PHanov rats have a defective insulin action, partially restored with metformin. PHiov rats had less severe alterations, and metformin treatment was more effective in this phenotype.
María Florencia Heber, Silvana Rocío Ferreira, Giselle Adriana Abruzzese, Raíces Trinidad, Omar P Pignataro, Margarita Vega, and Alicia B Motta
Giselle Adriana Abruzzese, Maria Florencia Heber, Silvana Rocío Ferreira, María José Ferrer, and Alicia Beatriz Motta
Prenatal androgen exposure affects reproductive functions and has been proposed as an underlying cause of polycystic ovary syndrome (PCOS). In this study, we aimed to investigate the impact of prenatal androgen exposure on ovarian lipid metabolism and to deepen our understanding of steroidogenesis regulation during adulthood. Pregnant rats were hyperandrogenized with testosterone and female offspring were studied when adult. This treatment leads to two different phenotypes: irregular ovulatory and anovulatory animals. Our results showed that prenatally hyperandrogenized (PH) animals displayed altered lipid and hormonal profile together with alterations in steroidogenesis and ovarian lipid metabolism. Moreover, PH animals showed alterations in the PPARg system, impaired mRNA levels of cholesterol receptors (Ldlr and Srb1) and decreased expression of the rate-limiting enzyme of de novo cholesterol production (Hmgcr). Anovulatory PH animals presented an increase of ovarian cholesteryl esters levels and lipid peroxidation index. Together with alterations in cholesterol metabolism, we found an impairment of the steroidogenic pathway in PH animals in a phenotype-specific manner. Regarding fatty acid metabolism, our results showed, in PH animals, an altered expression of Srebp1 and Atgl, which are involved in fatty acid metabolism and triglycerides hydrolysis, respectively. In conclusion, fatty acid and cholesterol metabolism, which are key players in steroidogenesis acting as a source of energy and substrate for steroid production, were affected in animals exposed to androgens during gestation. These results suggest that prenatal androgen exposure leads to long-term effects that affect ovary lipid metabolism and ovarian steroid formation from the very first steps.
Giselle Adriana Abruzzese, Maria Florencia Heber, Silvana Rocio Ferreira, Leandro Martin Velez, Roxana Reynoso, Omar Pedro Pignataro, and Alicia Beatriz Motta
Prenatal hyperandrogenism is hypothesized as one of the main factors contributing to the development of polycystic ovary syndrome (PCOS). PCOS patients have high risk of developing fatty liver and steatosis. This study aimed to evaluate the role of prenatal hyperandrogenism in liver lipid metabolism and fatty liver development. Pregnant rats were hyperandrogenized with testosterone. At pubertal age, the prenatally hyperandrogenized (PH) female offspring displayed both ovulatory (PHov) and anovulatory (PHanov) phenotypes that mimic human PCOS features. We evaluated hepatic transferases, liver lipid content, the balance between lipogenesis and fatty acid oxidation pathway, oxidant/antioxidant balance and proinflammatory status. We also evaluated the general metabolic status through growth rate curve, basal glucose and insulin levels, glucose tolerance test, HOMA-IR index and serum lipid profile. Although neither PH group showed signs of liver lipid content, the lipogenesis and fatty oxidation pathways were altered. The PH groups also showed impaired oxidant/antioxidant balance, a decrease in the proinflammatory pathway (measured by prostaglandin E2 and cyclooxygenase-2 levels), decreased glucose tolerance, imbalance of circulating lipids and increased risk of metabolic syndrome. We conclude that prenatal hyperandrogenism generates both PHov and PHanov phenotypes with signs of liver alterations, imbalance in lipid metabolism and increased risk of developing metabolic syndrome. The anovulatory phenotype showed more alterations in liver lipogenesis and a more impaired balance of insulin and glucose metabolism, being more susceptible to the development of steatosis.