Release and steroidogenic actions of polyunsaturated fatty acids in the goldfish testis

The aim of the present study was to examine the role of several polyunsaturated fatty acids (PUFA) in the control of steroidogenesis in the goldfish testis. The release of fatty acids from testis tissue in response to the protein kinase C activator phorbol-12-myristate-13-acetate (PMA) and calcium ionophore A23187 was studied. After a 2-h incubation, goldfish testis tissue released detectable amounts of several fatty acids, particularly docosahexaenoic acid (DHA). Treatment with PMA (100 nM) and A23187 (1 microM) increased the release of arachidonic acid (AA) and, to a lesser extent, of eicosapentaenoic acid (EPA). Further experiments showed that AA (100 and 400 microM) and, to a lesser extent, eicosatrienoic acid (ETA; 400 microM)--but not EPA or DHA (both 400 microM)--stimulated testicular testosterone (T) production via an indomethacin (INDO; 40 microM)--sensitive pathway, suggesting that these effects may be mediated through conversion to prostaglandins (PG). E-series PGs formed directly from ETA, AA, or EPA (PGE1, PGE2, or PGE3, respectively) all stimulate T production, with relative potencies of PGE2 > PGE1 > PGE3. The inability to detect ETA release from testis incubates and the limited effect of EPA on steroid production suggest that PGE2 represents the predominant E-series PG formed under physiological conditions in the goldfish testis. The steroidogenic action of AA was blocked by treatment with EPA or DHA, and this effect is due, partly, to inhibition of PGE2 formation from AA.(ABSTRACT TRUNCATED AT 250 WORDS)