Possibility of inhibin as a regulator of androstenedione production by theovary during the period of delayed ovulation in a vespertilionid bat, Scotophilus heathi

The aim of the present study was to evaluate the role of inhibin in regulat ing androstenedione production by the ovary of Scotophilus heathi during th e period of delayed ovulation. Inhibin alone increased the androstenedione synthesis in vitro by the ovary during all reproductive phases, but augment ed the hCG induced androstenedione production only during November. The fol licles produced significantly higher androstenedione as compared to the str omal or granulosa cell in response to both hCG and inhibin. However, inhibi n augmented hCG stimulated androstenedione in the stromal cell only. Immuno reactivity of inhibin subtype alpha, beta A and beta B were mainly localize d in the thecal and interstitial cell from September to November and then d eclined during the preovulatory period. However, in granulosa cells weak to moderate immunoreactivity of all inhibin subtype was observed during these phases. These results indicate the possible role of inhibin in regulating androstenedione synthesis by the ovary and thus, may be indirectly responsi ble for causing delayed ovulation in S. heathi. (C) 1999 Elsevier Science I nc. All rights reserved.