SYNTHESIS OF 17,20-ALPHA-DIHYDROXY-4-PREGNEN-3-ONE AND 17,20-BETA-DIHYDROXY-4-PREGNEN-3-ONE, 11-KETOTESTOSTERONE AND THEIR CONJUGATES BY GILLS OF TELEOST FISH

Goldfish, carp and trout gills were incubated with H-3-17-hydroxyproge sterone (17P). With goldfish gills, the metabolites were 17,20 alpha-d ihydroxy-4-pregnen-3-one (17,20 alpha P; 82%), 17,20 beta-dihydroxy-4- pregnen-3-one (17,20 beta P; 8%), 11-ketotestosterone (KT) glucuronide (5.4%) and 17,20 alpha P glucuronide (0.2%). Sulfates were not detect ed. Carp gills converted 17P into 17,20 alpha P (11.2%), 17,20 beta P (9.6%), KT (8.4%), glucuronides of 17,20 alpha P (1.3%) and 17,20 beta P (1.6%) and sulfates of 17,20 alpha P (5.1%) and 17,20 beta P (7.2%) . 17,20 beta P (38% free, 1.8% glucuronide and 21.1% sulfate) was the sole metabolite of H-3-17P in trout gill incubations. In the presence of high (10 mu g ml(-1)) substrate concentration, cyprinid gills gave predominantly free 17,20 alpha P, while trout gills yielded only free 17,20 beta P. Production of 17,20 beta P, predominantly as its sulfate , from endogenous precursors was demonstrated in trout gills but was n ot stimulated by trout primary extract. Our results demonstrate for th e first time the steroidogenic potential of teleost gills and suggest that they may play a role in secretion of pheromones in some species.