Progesterone metabolism in the ovaries and testes of the echinoid Lytechinus variegatus Lamarck (Echinodermata)

In the present study we examined the metabolic fate of progesterone (P4) in homogenate and tissue minces of the ovaries and testes of Lytechinus varie gatus. P4 was metabolized primarily into Su.-reduced metabolites including, 5 alpha -pregnane-3,20-dione (DHP),3 beta -hydroxy-5 alpha -pregnan-20-one (3 beta ,20-one), 5 alpha -pregnane-3 beta ,20 alpha -diol (3 beta ,20 alp ha -diol): 5 alpha -pregnane-3 beta ,20 beta -diol (3 beta ,20 beta -diol), and 5 alpha -pregnane-3 alpha ,20 alpha -diol (3 alpha ,20 alpha -diol) by both the ovaries and testes. The capacity to metabolize P4 did not differ between the ovaries and testes. However, the relative quantity of 5 alpha - pregnane-3 beta ,20 xi -diol synthesized from ovary and testis tissue mince s was about 3.3-fold higher than from homogenate preparations. Differences in the synthesis of 3 beta ,20-one and 3 alpha ,20 alpha -diol in both ovar y and testis minces were dependent on reproductive state. This study demons trates the pathway of P4 conversion in the ovaries and testes of L. variega tus and indicates the rapid conversion of P4 into 5 alpha -reduced metaboli tes in these tissues. Although P4 metabolism is not sex specific, sex-speci fic responses to P4 metabolites have been demonstrated previously. We hypot hesize that the sex-specific responses of the ovaries and the testes to P4 may be associated with receptor-level regulatory processes. (C) 2000 Elsevi er Science Inc. All rights reserved.