Somatostatin inhibits growth of rainbow trout

Implantation of rainbow trout Oncorhynchus mykiss with somatostatin-14 (SS- 14) for 20 days resulted in reduced food conversion as well as significant growth retardation compared to controls. Relative growth as mass was reduce d by 20%, whereas relative growth by length was reduced by 45%. A single in traperitoneal injection of SS-14 reduced plasma levels of growth hormone (G H), insulin-like growth factor-1 (IGF-I) and insulin. SS-14 injection also reduced [S-35]-sulphate incorporation into gill cartilage compared to salin e-injected fish. In addition, br vitro incubation of gill cartilage with SS -14 reduced [S-35]-sulphate incorporation in a dose-related manner. These r esults indicate that SS-14 inhibits growth of rainbow trout and suggests th at SS-14. in addition to influencing GH, may play an extra-pituitary role i n the modulation of the GH-IGF-I axis. (C) 2001 The Fisheries society of th e British Isles.