EFFECT OF METHALLIBURE ON GONADOTROPHIC CONTENT, OVARIAN 32P UPTAKE AND GONADOSOMATIC INDEX IN THE FRESHWATER CATFISH, HETEROPNEUSTES FOSSILIS (BLOCH)

Gonadotrophin content in the pituitary gland and blood serum as well as ovarian 32P uptake were studied in response to methallibure treatment in H. fossilis. There was a marked reduction in the gonadotrophic activity of the pituitary gland and blood serum within 3 weeks of methallibure treatment (100 microng/g). A simultaneous significant reduction was also recorded in the ovarian activity of these fish. The fall in ovarian activity caused by methallibure could not be prevented by the administration of LH, FSH or LH+FSH. After cessation of methallibure treatment, LH+FSH (50 microng each) administration restored ovarian activity. It is evident from these results that methallibure alters the secretion of gonadotrophin, and also prevents its action on the ovary.