In order to study the dual endocrine effect on the gonadotropin release of pituitary in the ancient Chondrostei fish,luteinizing hormone releasing hormone analog(LHRH-A)and dopamine(DA)were used in vitro to research their effect on gonadotropin release of pituitary fragment in Amur sturgeon(A.schrenckii).Two experiments were designed to study how the LHRH-A and DA affect the GtH release of pituitary fragment:Three times repetitive pulse stimulation of 10,100 and 1 000 nmol/L different dosages of LHRH-A were introduced every one hour for five minutes,perfusion;And then after two hours,perfusion of 200 nmol/L DA,1 000 nmol/L LHRH-stimulation was introduced for five minutes.The perfusate was collected every five minutes to test the GtH content using Radio Immunoassay(RIA)method.The results showed that repetitive pulse administration of LHRH-A was able to be stimulating GtH release from the pituitary fragments in vitro in Amur sturgeon,without dose-dependent manner at the dosage from 10 nmol/L to 1 000 nmol/L.It seemed LHRH-A at high concentration restrained the release of GtH by itself.Dopamine(DA)had no obvious effect on basal GtH secretion of pituitary while it could restrain the GtH release of pituitary fragment induced by LHRH-A.It proved that dual endocrine regulation of GtH release also existed in sturgeon.