Intrafollicular application of ACTH in dairy cows delay ovulation without changes in follicular blood flow.

BELOTTI EM; ETCHEVERS; FILIPPA E; AMWEG AN, ; ORMAECHEA NE; CHIARAVIGLIO JA; NOTARO US; ORTEGA HH; SALVETTI NR

Mar del Plata, Buenos Aires Argentina.

Congreso; Reunión Conjunta SAIC, SAI, FAIC, SAFIS 2022. LXVII Reunión Anual de la Sociedad Argentina de Investigación Clínica (SAIC). 16 al 19 de noviembre de 2022.; 2022

SAIC

Dairy cattle are subjected to stressfulsituations some of which can be associated to reproductive disruptions. In theovary, follicles receive blood supply through a complex network of bloodvessels. Functional and structural changes occur mainly in microvasculature ofthe follicular-luteal complex and have important roles in folliculogenesis andovulation. Under stressful conditions, the microenvironment of the ovary ismodified, affecting normal follicular dynamic. Previous studies have determinedthat adrenocorticotropic hormone (ACTH) is able to stimulate cortisol secretionin follicular wall in vitro and, additionally follicular cells express MC2Rreceptors. The aim of this study was to evaluate time to ovulation andhemodynamic changes in the ovulatory follicles after intrafollicular ACTHadministration. Multiparous Holstein x Jersey cows without reproductive diseasechecked by US were included on the study. Estrous cycles were synchronized byG6G protocol. Then, ACTH (10IU in 0.1mL) was administered two days beforeexpected day of ovulation, by US-guided intrafollicular injection (AG; N=5).Control group (CG; N=4) received 0.1 mL of physiological solution. PowerDoppler US was performed once a day during proestrus until ovulation.Follicular blood flow was quantified by Image J Software and a repeated- measuresanalysis was performed using the Generalized Linear Model approach to evaluatefollicular 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 onfollicular cells, it is likely that the delay in ovulation could be related toeffects of this hormone at local level. More studies for confirmation of thisdelayed ovulation and changes at molecular level must be carried out, howeverit can be proposed that these results are consistent with possible localeffects of ACTH on mechanisms involved in ovulation.