Expression of vascular endothelial growth factor (VEGF) and hypoxia inducible factors (HİFS) in the goat uterine and ovarian tissues during different pregnancy stages

Hypoxia-inducible factors (HIFs) and vascular endothelial growth factor (VEGF) play important roles in the establishment and maintenance of pregnancy. It is thought that these growth factors play important roles in vascular development, luteal development, implantation, and placentation in the gestation process. The objective of this study was to investigate expression level changes of HIFs (HIF-1A, HIF-2A, HIF-3A) and VEGF at mRNA and protein levels in goat uterine and ovarian tissues during different pregnancy stages. In this study, 42 female Hair goats were used as animal material. Female goats were divided into six different groups as embryo positive (Group 1; G1, 6-7th days post copulation), early pregnancy (Group 2; G2, 17-18th days post copulation), mid-pregnancy (Group 3; G3, 30th-day post copulation), late pregnancy (Group 4; G4, 60th-day post copulation), oocyte positive (Group 5; G1, 6-7th days after estrus (control group 1)) and diestrus group; G6, 16-17th days after estrus (control group 2)). The mRNA expression levels of the examined genes were evaluated by real-time quantitative polymerase chain reaction (RT-qPCR), and protein level changes were evaluated by immunohistochemistry. Beta actin and YWHAZ were used as housekeeping genes for the normalization of RT-qPCR data. In this study, it was detected that HIF-1A expression was higher in G1, G2, and G4 compared to mid-pregnancy (G3) in caruncules. No significant changes were observed in the expression of HIF-2A, HIF-3A, and VEGF between pregnancy groups. Expression of HIF-1A and HIF-2A was higher in G1 compared to G5. In cotyledons, the expression of HIF-1A and HIF-2A was higher during early (G2) and mid-term pregnancy (G3), compared to late pregnancy (G4). In the corpus luteum, it was detected that the expression of HIF-1A was higher in the process of rapid luteal development (G1, G2) compared to other pregnancy periods (G3 and G4). HIF-3A expression was higher in the late luteal stage (G6) than early luteal stage (G5). In immunohistochemical analysis, it was observed that HIF-1A immunoreactions increase with implantation and reach the highest level in mid-term pregnancy in the uterus. HIF-3A and VEGF immunoreactions were found to increase after implantation. HIF-1A and VEGF immunoreactions were higher during early luteal period in the corpus luteum. As a result, it was concluded that HIFs and VEGF play an important role in implantation, placentation, and luteal development processes in goats.