Placental expression and localization of endothelin-1 system and nitric oxide synthases during bovine pregnancy

This study aimed to investigate mRNA expression of the endothelin-1 (EDN1) system (preproEDN1; precursor, ECE-1; converting enzyme, EDNRA and EDNRB; receptor subtypes A and B) and endothelial and inducible nitric oxide synthases (eNOS and iNOS) in the bovine utero-placental unit during pregnancy. We also investigated the cellular localization of mRNA and protein of components of the EDN1 system in the placentome. The bovine utero-placental unit on Day 60, 100, 150, 200 and 250 of gestation was separated into carunclar areas (CAR), intercaruncular areas (ICAR), cotyledonary villi (COT) and intercotyledonary areas (ICOT). PreproEDN1, ECE1, EDNRA, EDNRB, eNOS and iNOS mRNA expression was determined by real-time quantitative RT-PCR. In situ hybridization and immunohistochemistry were performed using placentomes on Day 94 or Day 250 of gestation. PreproEDN1 and ECE1 mRNA expression was higher on Day 100 than on other gestation days. The mRNA expression for EDNRA in COT and ICOT and eNOS in COT, CAR and ICAR were higher on Day 150 than on other gestation days. EDNRB mRNA expression increased from Day 60 to Day 150 then decreased. iNOS mRNA expression in COT and CAR was higher on Day 250 than on other gestation days. PreproEDN1, ECE1 and EDNRA mRNA was localized in the caruncular epithelial cells (CEs) and the COT. EDNRB mRNA was found in the CEs and the trophoblast binucleate giant cells (BNCs). PreproEDN1, EDNRA and EDNRB proteins were detected in COT and CEs, whereas ECE-1 was found in the BNCs. Our results demonstrate that differential cell-specific and spatiotemporal expression of the EDN1 system and NOS in the bovine utero-placental unit may be associated with regulation of vascular and cellular functions during pregnancy.