CHANGES OF SEX STEROIDS IN MONOPTERUS ALBUS DURING ITS SPAWNING INDUCED WITH INJECTION OF LHRH-A

This paper reports, for the first time, the changes in concentrations of estra-diol(E2), progesterone(P)and testosterone(T)in serum of Monoptcrus albus du-ring the spawning induced with injection of LHRH-A(mammalian luteinizing hor-mone-releasing hOrmone analogues). The female fish injected with LHRH-A(0.3μg/gram body weight)exhibited a significant increase(P0.05)in serum E2 con-tent seven hrs after injection(A.I.).The E2 content reached its peak level 24 hrsA.I. The progesterone content showed also a similar increase: a significant rise inserum P content was observed 24 hrs A.I.(P0.05)and a more significant rise 48hrs A.I(P0.01). However, during the course of ovulation concentrations of E2and P decreased gradually towards their levels observed before injection. Changesin testosterone concentration showed a somewhat different pattern in serum of themale fish injected with LHRH-A: the peak concentration level of T was detected24 hrs A.I when spermiation took place and the T content decreased to its originallevel after spermiation. The theoretical basis was therefore presented on the useof sex steroids as an agent to induce spawning of M. albus.