Effect of sublethal hexavalent chromium exposure on the pituitary-ovarian axis of a teleost, Channa punctatus (Bloch).

Exposure to sublethal hexavalent chromium (as 2 and 4 mg L⁻¹ potassium dichromate for 1 and 2 months) during late preparatory to mid prespawning phase of annual reproductive cycle severely affected the pituitary-ovarian axis of a teleost Channa punctatus. Gonadosomatic index (GSI), ovarian histopathology, immunocytochemistry of the pituitary gonadotrophs (LHβ-immunoreactive cells), and serum 17β-estradiol level revealed distinct dose and duration-dependent effects. Gonadosomatic index was declined. Diameter of ovary as well as ovarian follicles was reduced along with a distinct variation in the percentage of follicles. The greater percentage of previtellogenic follicles (stage I) and decline in vitellogenic ones (stage II and stage III) compared to control indicated the arrest of follicular development. The percentage of atretic follicles was also increased indicating toxic impact of metal on ovary. Decreased serum level of ovarian steroid 17β-estradiol further indicated the same. Chromium interference of the pituitary was demonstrated as atrophy and less immunointensity of LH-immunoreactive gonadotrophs. Thus, the hexavalent chromium impaired the pituitary-ovarian axis affecting at the sites of both pituitary and ovary.