Abstract
Summary
1. ACTH, cortisone, corticosterone, desoxycorticosterone and pregnenolone were injected into newborn rats in varying dosage. Cortisone was found to be the most toxic with a total of 0.6 mg in the first few days of life being a lethal dose, as contrasted with the lack of toxicity of 0.25 mg of desoxycorticosterone given daily for 14 days. Cortisone was the most potent growth inhibitor and also the most potent stimulus for eruption of teeth, opening of eyelids and development of the gingivae. ACTH, although employed in larger doses than cortisone had a lesser effect on growth inhibition and little or no effect on development. Larger doses of ACTH are yet to be used. Corticosterone in the dose employed did not affect growth but did stimulate development. Pregnenolone in huge doses had no effect on either growth or development of teeth and eyelids. 2. Cortisone in a total dose of 0.5 mg (sub-lethal) given to newborn rats in the first week of life resulted in long-term damage to the animal as evidenced by failure to regain normal body weight 3 months after cessation of injections. The younger the animal at the time of the first injection, the more marked was the growth failure.
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