Hormonal control of the IGF system in the sea bream ovary.

Numerous studies have described the presence of an intragonadal IGF system involved in regulation of gametogenesis in teleost fish. In the present study, the in vivo effects of estradiol-17beta (E2) and growth hormone (GH) exposure on IGF-I, IGF-II, IGF1R, and IGFBP2 gene expression in sea bream ovary were monitored by RT-PCR during prereproductive and reproductive periods. The evidence demonstrates that both hormones investigated here affect the ovarian IGF system, showing that it is not only under GH control, but also can be regulated by sexual hormones; this hormonal modulation is related to reproductive phase.