Steroidogenesis by gonads of a viviparous teleost, the sailfin molly ( Poecilia latipinna), in vitro and in vivo

Gonads of Poecilia latipinna transformed [ 3H]testosterone into a number of reduced and conjugated metabolites in high yield in vitro. In the male 5β-androstane-3α,17β-diol, 5β-androstane-3β,17β-diol, and their “sulphates” were identified. The only 11-oxygenated androgen detected was a compound tentatively identified as 5β-androstane-3β,11β,17β-triol. In ovarian incubates androstenedione, 5β-androstane-3α,17β-diol and its glucuronide, testosterone glucuronide, and 5β-androstane-3α,17β-diol glucuronide were identified. Highest yields of the ovarian glucuronides coincided with the termination of vitellogenesis which may indicate a possible pheromonal role of these conjugates. In vivo plasma levels of estradiol in the female were correlated with vitellogenesis and fell markedly after castration or hypophysectomy. In males the plasma concentrations of testosterone, 11-ketotestosterone and 11β-hydroxytestosterone and their conjugates were variable and not apparently correlated with testicular weight, but they were reduced to undetectable levels by castration and hypophysectomy. The results suggest that 5α- and 5β-reduced steroids may play a role in the reproductive endocrinology of P. latipinna and that measurements of only the “classical” steroid hormones in this and possibly other species may give only a partial and misleading picture of endocrine changes.