PROSCAR(AT) (FINASTERIDE) INHIBITS 5-ALPHA-REDUCTASE ACTIVITY IN THE OVARIES AND TESTES OF LYTECHINUS-VARIEGATUS LAMARCK (ECHINODERMATA, ECHINOIDEA)

Recent investigations into the steroid metabolic pathway in the echino id Lytechinus variegatus demonstrated the capacity of the gonads to co nvert androstenedione, the classical mammalian precursor to bioactive androgens, into testosterone and a variety of 5 alpha-reduced androgen s including 5 alpha-androstane-3 beta,17 beta-diol and 5 alpha-androst ane-3 alpha,17 beta-diol. The synthesis of these steroids, which requi res 5 alpha-reductase activity, varies with sex and reproductive state in L. variegatus, suggesting that these steroids may be involved in r eproductive processes. The classical method of castration followed by steroid replacement therapy to determine the biological role of steroi ds in the gonads of higher vertebrates is not possible in echinoids. T herefore, this study was designed to determine the efficacy of finaste ride, a selective 5 alpha-reductase inhibitor in the mammalian prostat e gland, on 5 alpha-reductase activity in the gonads of L. variegatus. Finasteride inhibits echinoid 5 alpha-reductase in a dose-dependent m anner with IC50 approximate to 2.7 mu M for both ovaries and testes. T hese echinoid IC(50)s are significantly higher than those reported for humans and rats. In addition, oral administration of finasteride to t he echinoids appeared to inhibit 5 alpha-reductase with no apparent st ress (no spine loss) to the animals. These data suggest that finasteri de may be used to selectively and chemically ablate 5 alpha-reduced an drogen synthesis in the gonads of L. variegatus. (C) 1998 Elsevier Sci ence Inc. All rights reserved.