REGULATION OF PROSTAGLANDIN-E AND PROSTAGLANDIN-F PRODUCTION IN THE GOLDFISH TESTIS

The present studies have investigated the putative role of activators of different signal transduction pathways in the regulation of prostaglandin (PG) production by goldfish testis pieces in vitro. The protein kinase C activator (PKC) phorbol 12-myristate 13-acetate (PMA: 1.56-400 nM) and calcium ionophore A23187 (62.5-4000 nM) stimulated PGE and F production in a dose and time-dependent fashion. There was no synergism between A23187 and PMA in stimulating PG production. PGE levels were at least 4.5 times higher than PGF levels. The phorbol ester 4alpha phorbol didecanoate (400 nM), which does not activate PKC, had no effect on PGE production. The synthetic diacylglycerol 1-oleoyl-2-acetyl-sn-glycerol (100 muM), but not 1,2-dioctanoyl-sn-glycerol (100 muM), stimulated PGE production. Although the gonadotropin analog human chorionic gonadotropin (1 IU/ml), adenylate cyclase activator forskolin (2 muM) and testosterone (5 ng/ml) had no effect, the cyclic nucleotide phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (1 mM) and cyclic adenosine-3',5'-monophosphate analog dibutyryladenosine-3',5'-monophosphate (2 mM) inhibited PMA (400 nM) and A23187 (1 muM)-stimulated PGE production. PMA and A23187 (400 nM and 1 muM, respectively) -stimulated PGE production was inhibited by phospholipase A2 inhibitors 4-bromophenacyl bromide, quinacrine and chloroquine (all 6.25-400 muM) and by diacylglycerol lipase inhibitor RHC 80267 (10-100 muM), suggesting that both lipases are involved in the release of precursor fatty acids for PG synthesis by goldfish testis tissue. These data, in conjunction with earlier studies showing that PGE stimulates testosterone production by goldfish testis pieces, lend support to the contention that locally produced PGs of the E series modulate testicular steroidogenesis in teleosts.