Molecular characterization and regulation of the angiotensin-converting enzyme type 2/Angiotensin-(1-7)/MAS receptor axis during the ovulation process in cattle

The objective of this study was to characterize the profiles of Ang-(1-7), MAS receptor, ACE₂, NEP and PEP during the ovulatory process in cattle. For this study, 40 synchronized cows with follicular diameter ≥ 12 mm were ovariectomized at different time-points (0, 3, 6, 12 and 24 h) after i.m. application of gonadotropin-releasing hormone (GnRH) to induce a luteinizing hormone surge. Follicular fluid was collected for measuring Ang-(1-7) by radioimmunoassay. Theca and granulosa cells were isolated from the preovulatory follicles to evaluate the gene expression of MAS receptor, ACE₂, NEP and PEP by qRT-PCR assay. Cross-contamination between theca and granulosa cells was tested by RT-PCR to detect cytochrome P450 aromatase (CYP19A1) and 17α-hydroxylase (CYP17A1) mRNA. Ang-(1-7) levels were constant until 12 h and then increased (p < 0.05) at 24 h after GnRH. Messenger RNA expression of MAS, ACE₂, NEP and PEP was detected in theca and granulosa cells at all time-points after GnRH. In granulosa cells, ACE₂, NEP and PEP were differentially expressed after GnRH treatment (p < 0.05). In conclusion, the Ang-(1-7), MAS receptor, ACE₂, NEP and PEP profiles in preovulatory follicles indicate that Ang-(1-7) plays a role in the regulation of the ovulatory process in cattle.