The expression of angiotensin and endothelin system members in bovine corpus luteum during estrous cycle and pregnancy

The aim of this study was to determine the changing profiles of the mRNA expression of members of angiotensin and endothelin system in bovine corpus luteum (CL) from different stages of the estrous cycle and pregnancy. Corpora lutea were accordingly assigned to the following stages; d 1-2, 3-4, 5-7, 8-12, 13-18, >18 (after regression) of estrous cycle and of early and late pregnancy (<4 and >4 mo). The block RT-PCR analysis of CL showed a significantly higher angiotensin converting enzyme (ACE) mRNA expression during mid and late luteal phases as well as after regression, but lower levels during pregnancy. Full quantitative real-time RT-PCR (LightCycler) confirmed this pattern of ACE mRNA expression. The angiotensin receptor type I (AT1 R) mRNA expression was relatively stable throughout the periods examined. In contrast, AT2R mRNA temporarily decreased on d 8-12, followed by an increase to the highest levels during late luteal phase, and it remained at high levels during regression and pregnancy. Concentration of angiotensin II (Ang II) peptide in luteal tissue was highest after ovulation (d 1-2), decreased afterward, increased again during late luteal phase, and decreased to lower levels during regression and pregnancy. The mRNA expression and peptide concentration of endothelin 1 (ET-1) was high after ovulation followed by a decrease during mid and late luteal phases and increased again to the highest level after regression. The endothelin receptor type B (ETR-B) mRNA expression increased during late luteal phase and further after regression. In contrast, ETR-A and endothelin converting enzyme 1 (ECE-1) mRNA expression were relatively constant during all stages examined. In conclusion, the regulatory changes of both angiotensin and endothelin family members during early luteal phase and again during late luteal phase suggest a possible modulatory role of these vasoactive peptide families for bovine CL formation and regression.