The effect of 17β Estradiol on the growth hormone secretion by the pituitary of common carp was studied by using in vitro perifusion system for pituitary fragments. The basal GH release rose significantly 30 min after the introduction of E2(1 μmol/L) to the pituitary fragments of sexually mature common carp(GSI:15 6%~25 4%)

and reached the highest value of (377 8±99 5) ng/mL after 2 h. Then it reduced to (188 6±65 2) ng/mL without significant difference to the value before the E2 was introducted after 240 min of the E2 treatment.In this study

overnight E2 treatment did not alter the basal GH release. But it indicated that the effects of prolonged E2 exposure on LHRH stimulated and TRH stimulated GH release in common carp can be exerted directly at the pituitary level. E2 played an inhibition role in the LHRH stimulated GH release but a promoting role in the TRH stimulated one.