Levels of progesterone, testosterone, and estradiol, and androstenedione metabolism in the gonads of Lytechinus variegatus (Echinodermata : Echinoidea)

Levels of progesterone (P4), testosterone (T) and estradiol (E2) indicated significant variation among individual echinoids during the annual cycle, r eflecting generally the variation in gamete development that can be observe d among individuals. Testosterone and E2 levels in both the ovaries and tes tes were higher during the period of gonadal growth. Levels of all steroids were greatly reduced compared to those levels reported for asteroids. Diff erences in the levels of P4. T, and estrogens between asteroids and Lytechi nus variegatus may be related to differences in gonad morphology and nutrie nt storage capacity between asteroids and echinoids. It was hypothesized th at the low levels of steroids detected in L. varigatus reflect paracrine-li ke mechanisms in cell signaling as compared to endocrine-like mechanisms pr oposed to be involved in regulating gonad function in asteroids. Both the o varies and testes of L. variegatus had the capacity to synthesize T and a v ariety of 5 alpha-reduced androgens including 5 alpha-androstane-3 beta,17 beta-diol and 5 alpha-androstane-3 alpha, 17 beta-diol (5 alpha-adiols) fro m androstenedione (AD) in 8 h. Estrogen synthesis was not detected. The sex -specific pattern of accumulation of 5 alpha-adiols in the ovaries and test es suggests that the 5 alpha-adiols may affect processes related to reprodu ction in L. variegatus. (C) 2000 Elsevier Science Inc. All rights reserved.