IGF system: Involvement in the ovarian follicular persistence in cow

HUBER E; SALVETTI NR; GAREIS NC; ORTEGA HH; RODRÍGUEZ FM; STASSI AF; REY F

Mar del Plata

Congreso; Reunión anual de SAIC, SAI, SAFE; 2016

Ovarianfunctions are controlled by several hormones as insulin-like growth factor(IGF) system. It has been postulated that alterations in IGF system would beinvolved in cystic ovarian disease (COD) development. The aim of this study wasto evaluate the role of members of IGF system that were altered in COD, in theestablishment of bovine persistent ovarian follicles. Thus, IGF1, its receptorIGFR1, the binding protein IGFBP4 and the hydrolytic enzyme PAPP-A wereevaluated in ovarian samples. Estral cycles of non-lactating Holstein cows(n=25) were synchronized and then, animals were divided in five groups: control(without hormonal treatment) and 0 (day of ovulation), 5, 10 and 15 days offollicular persistence. Persistent follicles were obtained from cows treated withlong-term subluteal progesterone administration using an intravaginalprogesterone-releasing device. Concentrations of IGF1 determined byradioimmunoassay and levels IGFBP4 evaluated by western blot (WB) in follicularfluid (FF), were similar in all the stages of persistence and preovulatoryfollicles. IGFR1 expression analyzed by immunohistochemistry (IHC) was higherin the granulosa of persistent follicles of P0, P10 and P15 (p <0.05) thanin preovulatory follicles. IGFBP4 protein expression analyzed by IHC wasgreater in all the stages of persistence than in preovulatory follicles(p<0.05). No differences were detected by WB in PAPP- A secreted to FF inall persistent follicles compared with preovulatory follicles. Results of thisstudy showed that several changes previously determined in animals with COD arepresented at initial stages of follicular persistence. These alterations in IGFsystem affect the normal ovarian follicular development and could lead to thedevelopment of the COD. These data confirm an essential role of the IGF systemin the pathogenesis of COD in cattle.