EFFECTS OF HYPOPHYSECTOMY, GROWTH HORMONE, THYROXIN AND FOOD INTAKE ON CATHEPSIN ACTIVITY OF RAT TISSUES

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Abstract
Assays of cathepsin in the kidney, spleen, and liver of hypophysectomized rats yield lower values than in normals, particularly in liver. Growth hormone produced a consistent rise in cathepsins of the 3 organs only when large doses were given to hypophysectomized and normal animals which were pair-fed against hypophysectomized controls, and therefore incapable of a maximal response with respect to gain in wt. Under conditions of ad lib. feeding, daily injn. for 10 days of 20-80 [mu]g. doses of growth hormone, having an effect on wt. 38% as great as that of purified hormone, did not restore cathepsin values. Daily injn. of 50 [mu]g. of thyroxine greatly increased hepatic cathepsins in hypophysectomized as well as in normal rats. The low values in the former animals are thus ascribed to deficiency of thyrotropin rather than somatotropin. Cathepsin activity in the 3 organs examined remains constant during changes in organ wt. which would dilute these enzymes several times if they were inert cell constituents.