Effects of gonadotropin-releasing hormone analog (GnRHa) on steroidogenic factor-1 (SF-1) and estrogen receptor beta (ERbeta) gene expression in the black porgy (Acanthopagrus schlegeli).

We examined effects of GnRHa on expression of steroidogenic factor-1 (SF-1) and estrogen receptor beta (ERbeta) in the pituitary and gonad of protandrous black porgy (Acanthopagrus schlegeli). Fish were intraperitoneally injected with 0.2 microg GnRHa/g fish and then pituitary, gonad and plasma were sampled at 0, 6, 12, 24 and 48 h after injection. In gonad, the mRNA levels of the SF-1 were high at 6 h post injection, and then continuously decreased until 24 h; high expression of ERbeta mRNA levels was only observed at 12 h. In contrast, pituitary SF-1 mRNA levels were very low during the experimental period. GnRHa stimulation caused a significant increase of plasma testosterone (T) and estradiol-17beta (E(2)) after 24 h. We suggest that SF-1 and ERbeta play an important role in the development of gonad and these genes are involved with sex change in fish.