Androgens and estradiol-17β production by porcine uterine cells: In vitro study

Porcine (Sus scrofa domestica) uterine slices harvested during both early pregnancy and luteolysis produce steroid hormones. The aim of the present study was to determine (1) which porcine separated uterine cells secrete androgens: androstenedione (A4) and testosterone (T), and estradiol-17β (E2) in culture; (2) if the production of A4, T and E2 in the uterine cells is regulated by P4 and OT; (3) if uterine tissues expressed cytochrome P450arom gene (CYP19). Uteri were collected on Days 14 to 16 of early pregnancy and the estrous cycle. Enzymatically separated epithelial cells, stromal cells, and myocytes were cultured in vitro for 2, 6, and 12 h with control medium, progesterone (P4; 10–5 M), oxytocin (OT; 10–7 M), and both hormones (P4 + OT). The studied cells secreted A4, T, and E2 in vitro. Progesterone served as a substrate for steroid synthesis in the uterine cells. Isolated uterine cells, cultured separately, contributed in equal portion to the basal production of androgens (A4 and T) during both early pregnancy and luteolysis. In pregnant pigs, the epithelial and stromal cells were rich sources of E2 compared with myocytes. Myocytes produced E2 mainly during luteolysis. Pregnant porcine endometrium and myometrium expressed the gene CYP19, which encodes for P450 aromatase, a steroidogenic enzyme. The results indicate an active steroidogenic pathway in porcine uterine cells. The epithelial cells, stromal cells, and myocytes participate in steroid production as an alternative source for their action in pigs.