Blood Corticosterone-levels in the Rat after Administration of Amino-acids

Abstract

Munro and Mukerji¹ observed that the feeding of single large doses of certain individual amino-acids, notably glycine, methionine and leucine, caused a marked stimulation of uptake of phosphorus-32 by rat-liver ribonucleic acid (RNA) during the next 18 h. In the case of methionine and leucine, but not of glycine, this action was abolished by adrenalectomy². It was therefore proposed that the increased incorporation of phosphorus-32 into liver RNA after feeding methionine or leucine was due to release of adrenocortical hormones, which are known to induce changes in liver RNA metabolism³. The experiments reported here show that, within a 24-h period of administering methionine or leucine to rats, there is an elevation of blood corticosterone-level. Administration of other amino-acids or of casein does not have this effect. These observations would thus appear to confirm the proposed mechanism of action of methionine and leucine on liver RNA metabolism.