In vitro effect of cortisol and urotensin I on arginine vasotocin and isotocin secretion from pituitary cells of gilthead sea bream Sparus aurata

This study aimed at determining whether in vitro secretion of two neuropeptides, arginine vasotocin ( AVT ) and isotocin ( IT ), from pituitary cells of gilthead sea bream Sparus aurata was affected by cortisol and urotensin ( UI ). Pituitary cells were exposed to 1·4 × 10 −8 , 1·4 × 10 −7 and 0·4 × 10 −6  M cortisol and 10 −12 , 10 −10 and 10 −8  M UI for 6, 24 and 48 h, respectively. AVT and IT contents were determined in the culture media by high‐performance liquid chromatography ( HPLC ). An increase in AVT secretion and a decrease in IT secretion were observed at all cortisol doses. UI increased AVT secretion after 6 h of incubation at all doses. After 24 h, however, only the highest dose of UI still displayed an effect. IT secretion was not influenced by UI . It was thus demonstrated that cortisol does influence AVT and IT secretion from S. aurata pituitary cells, while UI regulates AVT secretion, as a component of hypothalamic–pituitary–interrenal ( HPI ) axis in this species.