Development and validation of a carp growth hormone radioimmunoassay

Purified growth hormone (GH), isolated from pituitary glands of the common carp (Cyprinus carpio), was shown to have biochemical and immunological properties in common with other teleost GH preparations. Intraperitoneal injections of the carp GH, at a dose of 1 microgram/g body wt, resulted in significant increases in body weight in goldfish. In addition, the carp GH was used to prepare an antiserum for the development of a radioimmunoassay (RIA). The displacement curves for serum from goldfish with an intact pituitary gland were parallel to that of the purified cGH in this RIA. In contrast, serial dilutions of serum from hypophysectomized goldfish, and purified goldfish prolactin and carp gonadotropin did not have significant cross reaction. The present study strongly suggests that this RIA is suitable for the measurement of circulating GH levels in the goldfish.