Development of a salmon growth hormone radioimmunoassay

This study describes the development of a growth hormone (GH) radioimmunoassay (RIA) using chum salmon ( Oncorhynchus keta) GH and an antiserum raised against this preparation. The assay does not cross-react with salmon prolactin and is valid for the genera Salmo and Oncorhynchus. Hypophysectomy of coho salmon ( O. kisutch) reduced plasma immunoreactivity to nondetectable levels in seven of eight individuals. Handling stress had no effect upon GH levels in the rainbow trout ( Salmo gairdneri) whereas starvation (3 weeks) induced a ninefold increase in plasma immunoreactivity. Plasma GH levels in trout were positively correlated, following a lag-phase of 1 week, with the weekly changes in growth rate displayed by this species.