Intra-adrenal interactions in fish: catecholamine stimulated cortisol release in sea bass (Dicentrarchus labrax L.).

The effect of the catecholamines, adrenaline and noradrenaline, on sea bass (Dicentrarchus labrax) and sea bream (Sparus auratus) interrenal cortisol production was studied in vitro using a dynamic superfusion system technique. Increasing concentrations of catecholamines (10(-6), 10(-8) and 10(-10) M) stimulated cortisol production in a dose-dependent manner, in sea bass only. The increase in cortisol production stimulated by adrenaline (10(-6) M) and noradrenaline (10(-6) M) was inhibited by sotalol (2 x 10(-5) M), but not by prazosin suggesting that catecholamines stimulate cortisol release through the beta-receptor subtype. To evaluate catecholamine-induced signal transduction in head kidney cells, measurements of cAMP production and [H3]myo-inositol incorporation were determined in head kidney cell suspensions. Adrenaline and noradrenaline (10(-6) M) increased cAMP production, but had no effect on total inositol phosphate accumulation. These results indicate that catecholamines released from the chromaffin cells within the interrenal tissue may act as a paracrine factor to stimulate interrenal steroidogenesis in the sea bass.