Ovarian expression of inhibin-subunits, 3β-hydroxysteroid dehydrogenase, and cytochrome P450 aromatase during the estrous cycle and pregnancy of shiba goats (Capra hircus).

The cellular localization of the inhibin subunits (α, β(A), and β (B)), steroidogenic enzymes (3β-hydroxysteroid dehydrogenase (3βHSD) and cytochrome P450 aromatase (P450arom) were evaluated in the ovaries of cyclic (n=6) and pregnant (n=2) Shiba goats (Capra Hircus). The immunointensity of inhibin α and β(A) subunits showed an increase in the granulosa cells (GC) of developing follicles. Inhibin β(B) subunit and P450arom showed high expression in GC of antral follicles. 3βHSD immunoreactivity was uniform in preantral and antral follicles. In follicular phase and late pregnancy, there was a strong expression of inhibin α subunit in GC of antral follicles. Although in mid pregnancy, antral follicles GC showed moderate immunostaining of inhibin β subunits, the immunoreactivity of inhibin β(A) and β(B) subunits was high during the follicular and luteal stages, respectively. While, immunoreactivity of GC to P450arom was moderate during all studied stages, and 3βHSD immunoreactivity was plentiful in antral follicles during the luteal phase. The immunoreactivity to inhibin α subunit and P450arom was abundant during mid pregnancy in the luteal tissues. Immunoreaction to inhibin β subunits was faint-to-moderate in cyclic and pregnancy corpora lutea. Immunoexpression of 3βHSD was maximal in late pregnancy corpora lutea. The present results suggest that, in goats, the GC of antral follicles are the main source of dimeric inhibins and that corpora lutea may partially participate in the secretion of inhibin. Changes in ovarian hormonal levels might depend on the synthesizing capacity of hormones in the follicles and corpora lutea to regulate the goat's reproductive stages.