Effect of Prolactin, Growth Hormone and ACTH on the Urea Excretion of Bullfrog Tadpoles During Normal and Induced Metamorphosis1

The urea excretion of premetamorphictadpoles was decreased by prolactin(0.1-1.0 μg/g in 3 injections) and growth hormone (0.3 or 1.0 μg/g—3 injections, or 100 μg/g—single injection). A single injection of a larger dose of prolactin (100 μg/g) did not cause any change inurea excretion in these tadpoles. ACTH (0.020 USP U/g) increased urea excretion on the fourth and fifth days. The body weight and tail length of normal tadpoles were increased by prolactin and growth hormone, but not by ACTH. Both the urea excretion and tail resorption of spontaneously metamorphosing tadpoles were not affected by a single injection of prolactin, growth hormone or ACTH. Prolactin (10 or 100 μg/g) inhibited the T3-induced (at doses of 0.03 or 0.10 nmole/g) urea excretion and tail resorption. Inhibition was also noted at lower doses of prolactin. Similarly, growth hormone at doses aslow as 0.1 μg/g reduced the action of T3 on urea excretion and tail resorption.ACTH seemed to augment the action of T3 on urea excretion but not on the tail. Albumin inhibited the action of T3 and, more markedly, of T4 on the urea response in tadpoles when both albumin and T3 or T4 were administered intraperitoneally, but had no effect when given by different routes.γ-Globulin showed no inhibitory effect regardless of test route. (Endocrinology87: 356, 1970)