Effects of LHRH-A and HCG on the steroid profiles of bisexual and mature male and female protandrous black porgy, Acanthopagrus schlegeli

Abstract

The major objective was to investigate plasma steroid profiles after stimulation with LHRH-A or HCG during the bisexual, mature male and female phases in black porgy, Acanthopagrus schlegeli, a marine protandrous hermaphrodite. The responses of milt volume and oocyte diameters were also studied. Two-year-old black porgy during the non-spawning (bisexual stage) and spawning season (male phase), and wild-captured mature females, were injected with a superactive analogue of mammalian luteinizing hormone releasing hormone (LHRH-A) and human chorionic gonadotropin (HCG). Plasma samples were taken from fish before and after injection. Milt volume and oocyte diameters were also measured in mature males and females. Plasma testosterone in the bisexual and mature male phase increased significantly after treatment with LHRH-A or HCG. Plasma estradiol-17 β and testosterone also increased in mature females after treatment. Peak levels of plasma testosterone occurred earlier in the mature male phase than in the bisexual stage. Spermiation and oocyte maturation were also stimulated during the spawning season after injection of LHRH-A and HCG. Peak levels of plasma progesterone and 17 α-hydroxyprogesterone were not found after stimulation.