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.