Estrogenic Regulation of Reproduction in Teleosts

Abstract

Teleost exhibits extreme plasticity in its sexuality, retaining the conserved vertebrate neuroendocrine regulation of reproduction. The sex hormonal milieu is a major driver of sexual development in an organism. In teleosts, 17β-estradiol (E2) and 11-ketotestosterone (11-KT) act as natural inducers of ovarian and testicular differentiation, respectively, and alteration in the sex steroid milieu can reverse their sex. Estrogen also exerts pleiotropic effects on other physiological processes, in addition to its reproductive role. Different research strategies have indicated that estradiol, from either peripheral or central origin, exerts nucleus- and membrane-initiated signalling mechanisms which cooperate with other signalling pathways to modulate biologic responses of both reproductive and non-reproductive nature. Sex steroids also maintain a self-regulating feedback loop along the brain-pituitary-gonadotropic axis for a stage- and sex-specific steroidogenesis and reproductive behavior, though the underlying molecular mechanisms remain elusive. Understanding the estrogen signalling will enhance our understanding of fish reproduction and its regulation and will provide opportunities for the development of new strategies useful to aquaculture.