Biological Activity of Bullfrog Growth Hormone in the Rat and the Bullfrog (Rana catesbeiana)

Highly purified bullfrog growth hormone (GH) was tested for growth promoting activity in rats and bullfrogs (Rana catesbeiana). In repeated assays, the potency of bullfrog GH in the rat tibia assay was 1 X bovine GH, which is significantly greater than all other non-mammalian GHs tested. It also stimulated significant whole body growth in immature hypophysectomized rats injected daily for 16 days. In bullfrogs, the bullfrog GH (about 2 microgram/injection) stimulated growth and appetite in intact frogs, and improved survival in hypophysectomized frogs. In contrast, even relatively high doses of bovine GH (up to 200 microgram/injection) were inactive in the bullfrog.