Angiotensin II profile and mRNA encoding RAS proteins during bovine follicular wave

Angiotensin II (AngII) has a role in ovarian follicle development, ovulation, and oocyte meiotic resumption. The objective of the present study was to characterise the AngII profile and the mRNA encoding RAS proteins in a bovine follicular wave. Cows were ovariectomised when the size between the largest (F1) and the second largest follicle (F2) was not statistically different (day 2), slightly different (day 3), or markedly different (day 4). AngII was measured in the follicular fluid and the mRNA abundance of genes encoding angiotensin-converting enzyme (ACE), (pro)renin receptor, and renin-binding protein (RnBP) was evaluated in the follicular cells from F1 and F2. The AngII levels increased at the expected time of the follicular deviation in F1 but did not change in F2. However, the expression of the genes encoding ACE, (pro)renin receptor, and RnBP was not regulated in F1 but was upregulated during or after the follicular deviation in F2. Moreover, RnBP gene expression increased when the F1 was treated with the oestrogen receptor-antagonist in vivo. In conclusion, the AngII concentration increased in the follicular fluid of the dominant follicle during and after deviation and further supports our finding that RAS is present in the ovary regulating follicular dominance.