INTRAFOLLICULAR APPLICATION OF ACTH IN DAIRY COWS DELAY OVULATION WITHOUT CHANGES IN FOLLICULAR BLOOD FLOW

BELOTTI, EM.; ETCHEVERS, L; FILIPPA, E; AMWEG, AN; ORMAECHEA, N; CHIARAVIGLIO, JA; NOTARO, U.S.; ORTEGA, HH; SALVETTI, N. R.

Congreso; LXVII Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica (SAIC).; 2022

Dairy cattle are subjected to stressful situations some of which can be associated to reproductive disruptions. In the ovary, follicles receive blood supply through a complex network of blood vessels. Functional and structural changes occur mainly in microvasculature of the follicular-luteal complex and have important roles in folliculogenesis and ovulation. Under stressful conditions, the Microenvironment of the ovary is modified, affecting normal follicular dynamic. Previous studies have determined that adrenocorticotropic hormone (ACTH) is able to stimulate cortisol secretion in follicular wall in vitro and, additionally follicular cells express MC2R receptors. The aim of this study was to evaluate time to ovulation and hemodynamic changes in the ovulatory follicles after Intrafollicular ACTH administration. Multiparous Holstein x Jersey cows without reproductive disease checked by US were included on the study. Estrous cycles were synchronized by G6G protocol. Then, ACTH (10IU in 0.1mL) was administered two days before expected day of ovulation, by US-guided intrafollicular injection (AG; N=5). Control group (CG; N=4) received 0.1 mL of Fhysiological solution. Power Doppler US was performed once a day during proestrus until ovulation. Follicular blood flow was quantified by Image J Software and a repeated-measures analysis was performed using the Generalized Linear Model approach to evaluate follicular blood flow. No differences were observed on follicular blood flow, although a delay on ovulation time (days) was observed on treated cows (CG=19.75 +/- 0.95 vs AG=22.5 +/- 3.1). Considering ACTH receptors on follicular cells, it is likely that the delay in ovulation could be related to effects of this hormone at local level. More studies for confirmation of this delayed ovulation and changes at molecular level must be carried out, however it can be proposed that these results are consistent with possible local effects of ACTH on mechanisms involved in ovulation.