BIOACTIVITY OF STORED LUTEINIZING-HORMONE-RELEASING HORMONE ANALOG (LHRHA) IN SEA BASS, LATES-CALCARIFER BLOCH

The spawning induction activity of dissolved and pelleted (D-Ala(6), P ro(9) N ethylamide) luteinizing hormone-releasing hormone analogue (LH RHa) stored for various periods was assessed in mature female sea bass . The spawning response of mature fish was reduced significantly after injection of dissolved LHRHa (20 mu g kg(-1)) stored for more than 90 days in a refrigerator (4-10 degrees C) or for more than 30 days at r oom temperature (28-30 degrees C). Similar to fish administered fresh preparations of LHRHa, fish spawned successfully after injection of a solution of LHRHa previously frozen, subjected to alternate freezing a nd thawing, exposed to sunlight or implanted pelleted LHRHa (50 mu g k g(-1)) stored at room temperature for 30-120 days. Loss of hormone bio activity after prolonged storage may have been due to bacterial growth in solubilized preparations. Injection or implantation of stored LHRH a did not influence egg production among treated sea bass. These resul ts demonstrated the relatively prolonged shelf life of stored LHRHa.