The presence of 3β-hydroxysteroid dehydrogenase in the ovarian follicles and corpora lutea of pregnant swine

Steroid hormones play an essential role in the ovarian cyclicity control and the progress of pregnancy. One of the crucial enzymes in the steroidogenesis is 3 beta-hydroxysteroid dehydrogenase/Delta 5-Delta 4 isomerase (3 beta HSD). The aim of the present study was to localize both 3 beta HSD mRNA and protein in the ovary of pregnant swine. The immunolocalization of 3 beta HSD was performed on paraplast sections of follicles and corpora lutea obtained on various days of gestation: 10, 18, 32, 50, 71 and 90 post coitum (p.c.). The obtained results were compared with those concerning follicular and luteal development in the ovaries of the cycling pig. Differences in 3 beta HSD distribution between the ovarian follicles of cycling and pregnant pigs were concerned mainly in the pattern of immunostaining of the theca interna cells. In the porcine ovaries obtained on various days of pregnancy, some follicles exhibited positive immunostaining in most theca interna cells, while in other follicles this enzyme was expressed only in a relatively small percentage of theca interna cells. In the corpora lutea of the estrous cycle and pregnancy changes in the pattern of immunostaining were observed. At early and mid pregnancy (up to 71 day p.c.) 3 beta HSD was observed in the large luteal cells while on day 71 p.c. the enzyme was present exclusively in the small luteal cells. The expression of 3 beta HSD mRNA was detected by the use of RT-PCR technique in all investigated samples isolated at different stages of pregnancy.