Evaluation of steroidogenic enzymes in a model of follicular persistence in dairy cows

CATTANEO MOREYRA ML; GAREIS NC; HEIN GJ; ANGELI E; ORTEGA HH; SALVETTI NR; RODRÍGUEZ FM; REY F

Mar del Plata

Congreso; Reunión Anual de Sociedades de Biociencias; 2022

In dairy cows with cystic ovariandisease, steroid hormones and proteinlevels of steroidogenic enzymes have been reported to be altered. Furthermore, in cows with ovarian follicularpersistence, alteredconcentrations of estradiol in serum and follicular fluid were observed. Therefore, we aimed to evaluate the proteinexpression of enzymes involved inthe synthesis of steroid hormones (StAR, CYP19, CYP17 and 3β-HSD) in ovarian tissue of cows with follicular persistence. Holando Argentino cows with healthyreproductive tract (n=25) weresubjected to estrous cycles synchronization with a G6G-Ovsynch protocol. While cows of the control group(CG, n= 5) were only synchronized,cows of the experimental groups with 0 (P0, n=5), 5 (P5, n=5), 10 (P10; n=5) and 15 days ofpersistence (P15; n=5), were alsotreated with progesterone intravaginally (P4). Finally, the ovaries were obtained by bilateral ovariectomy.Histological ovarian sections wereused for the indirect immunohistochemistry to localize and quantify in situ protein expression of StAR,CYP19, CYP17 and 3β-HSD in persistent and control follicles. Protein expression of CYP17 in theca cells and StAR in granulosa andtheca cells was similar in theanalysed groups (p>0.05). Lower CYP19 expression was detected in the P5 and P15 groupscompared to the control group(p<0.05). The expression of 3β-HSD was greater in granulosa and theca cells in the persistentfollicles of P15 group compared tofollicles of P0 group (p<0.05). In addition, in granulosa cells, a greater expression was detected in the P10group compared to the P0 group(p<0.05). These results show a local alteration of the enzymes involved in the steroidogenic pathway duringpersistence. Considering the resultsregistered in cows with cysts, we could infer that the alterations in CYP19 and 3β-HSD occur before the cysts development.