Alterations in the insulin signaling pathway in bovine ovaries with experimentally induced follicular persistence

GAREIS, NATALIA CAROLINA; STASSI, ANTONELA FLORENCIA; HUBER, EMILIA; RODRÍGUEZ, FERNANDA MARIEL; CATTANEO MOREYRA, MARÍA LUCÍA; SALVETTI, NATALIA RAQUEL; ORTEGA, HUGO HÉCTOR; HEIN, GUSTAVO JUAN; REY, FLORENCIA

THERIOGENOLOGY

ELSEVIER SCIENCE INC

Año: 2020 vol. 158 p. 158 - 167

0093-691X

Reproductive diseases in dairy cows as cystic ovarian disease (COD) represent a major problem thatimpacts on dairy production. COD is characterized by anovulation, persistence of the dominant follicle,and interruption of normal estrous cycles. Anovulation is attributable to a failure in the LH surge, due toendocrine imbalances and alterations in local factors, such as the insulin signaling pathway. Thus, theaim of this study was to examine the expression of critical nodes of the insulin pathway, including insulinreceptor (IR), IR substrate (IRS), phosphatidylinositol-3-kinase (PI3K), and protein kinase B (also knownas Akt or pan-Akt), in ovarian follicular structures of cows during the development of follicular persistenceinduced by long-term progesterone administration. Immunoexpression of IR, p-IR, IRS1, p-IRS1,PI3K, pan-Akt and p-pan-Akt was evaluated in situ by immunohistochemistry and the concentration ofinsulin in serum and follicular fluid was determined by radioimmunoassay. p-IR, p-IRS1, PI3K and p-pan-Akt expression was decreased in follicles at different times of persistence in relation to the controldominant follicles, in both granulosa and theca cells, whereas IR and IRS1 immunoexpression wasdecreased in persistent follicles at 5 and 15 days of persistence in granulosa cells. Serum and follicularfluid insulin concentrationwas higher in cows with persistent follicles than in control cows. These resultsshow that decreased expression and/or activation of the receptors and other intermediates of the insulinsignaling pathway in persistent follicles indicates that reduced response/resistance to insulin rather thanthe concentration of insulin per se may be one of the important molecular mechanisms in the developmentof persistent follicles in dairy cows.