Effect of extracellular osmolality and ionic levels on pituitary prolactin release in euryhaline silver sea bream (Sparus sarba).

In many euryhaline fish, prolactin (PRL) plays a key role in freshwater adaptation. Consistent with this function, the present study showed a remarkable reduction in pituitary PRL content of silver sea bream abruptly transferred to low salinity (6ppt). This reduction in pituitary PRL content followed closely the temporal changes in serum osmolality and ion levels.