STIMULATION OF MACROPHAGE PHAGOCYTOSIS AND LYMPHOCYTE COUNT BY EXOGENOUS PROLACTIN ADMINISTRATION IN SILVER SEA BREAM (SPARUS-SARBA) ADAPTED TO HYPEROSMOTIC AND HYPOOSMOTIC SALINITIES

Juvenile silver sea bream (Sparus sarba) were adapted to hyper-(33 ppt ) and hypo-osmotic (6 ppt) salinities for 3 weeks and injected daily w ith ovine prolactin (1 mu g/g body weight i.p.) during the last 7 days of the adaptation period. Fish injected with prolactin exhibited sign ificant increases in percent phagocytosis and phagocytic index of both pronephric and splenic macrophages regardless of salinity. Prolactin injection also resulted in elevated blood lymphocyte counts in both hy per-and hypo-osmotically adapted sea bream. The present results provid e further evidence for the existence of a neuroendocrine-immune link i n teleosts. (C) 1998 Elsevier Science B.V.