MC2R/MRAP2 activation could affect bovine ovarian steroidogenesis potential after ACTH treatment

ETCHEVERS L; BELOTTI EM; DÍAZ PU; RODRÍGUEZ FM; REY F; SALVETTI NR; ORTEGA HH; AMWEG AN

THERIOGENOLOGY

ELSEVIER SCIENCE INC

Lugar: Amsterdam; Año: 2021

0093-691X

Stressorsactivate the hypothalamicepituitaryeadrenal (HPA) axis, reducing fertility byinterfering with the mechanisms that regulate the timing of events within thefollicular phase of the estrous cycle. In the HPA axis, melanocortin 2 receptor(MC2R) mediates responses to adrenocorticotropic hormone (ACTH) in concert withmelanocortin receptor accessory protein 2 (MRAP2). The aims of the presentstudy were: (1) to evaluate the effects of ACTH administered in cows in thepreovulatory period on the expression of the MC2R/MRAP2 complex in the dominantfollicle; and (2) to analyze the involvement of Extracellular signal RegulatedKinase 1 (ERK1) signaling in the activation of MC2R and the expression of keyenzymes involved in the biosynthesis of glucocorticoids (GCs) in the dominantfollicle. To this end, 100 IU ACTH was administered to Holstein cows from alocal dairy farm during pro-estrus every 12 h for four days until ovariectomy,which was performed before ovulation. Protein immunostaining of MC2R was higherin the dominant follicles of ACTH-treated cows (p < 0.05). Also, Westernblot analysis showed higher activation of the ERK1 signaling pathway inACTH-treated cows (p < 0.05). Finally, immunohistochemistry performed in thedominant follicles of ACTH-treated cows detected higher expression of CYP17A1 andCYP21A2 (p < 0.05). These results suggest that the bovine ovary is able torespond locally to ACTH as a consequence of stress altering the expression ofrelevant steroidogenic enzymes. The results also confirm that the complete GCbiosynthesis pathway is present in bovine dominant follicle and therefore GCscould be produced locally.