Effect of glucocorticoids on spermiation and testosterone production in toad testes

E. REGUEIRA AND N. R. CEBALLOS

Genova, Italia

Conferencia; 24th Conference of European Comparative Endocrinologist; 2008

In rat, glucocorticoids (GC) inhibit testosterone (T) synthesis through the glucocorticoid receptors (GR). In toad testes, a GR with similar properties than rat receptor was described. The aim of this work is to analyze the effect of GC on spermiation and steroidogenesis by culturing testes with dexamethasone (DEX), corticosterone (B), with or without RU486 (antagonist of type 2 GR) and glycyrrhetinic acid (GA), an 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD-2) inhibitor. After 24-hr treatment with GC, hCG-induced spermiation and basal as well as hCG-stimulated T production were assayed. T was measured by RIA while hCG-induced spermiation by counting spermatozoa in the incubation media. GC decreases T secretion in a doses-dependent manner, the effect being abolished by RU486. However, the ratio hCG-induced/basal T production was not modified. The effect of low doses of GC was enhanced by GA, suggesting that 11betaHSD-2 modulates the effect. After GC treatment, hCG-induced spermiation decreased but in the presence of 15 nM DEX or 15 and 150 nM B spermiation was similar to control. These results suggest that low concentrations of CORT could abolish the negative effect of preincubation on spermiation. The presence of GA did not modify the effect of CORT on hCG-induced spermiation while RU486 completely abolished the effect of CORT, suggesting that the action of GC on spermiation and T production is due to its interaction with the GR on different cell types.