Reversal of thyroxine-induced hypermetabolism by puromycin.

Previous studies have demonstrated that in addition to its effects on metabolic rate, thyroxine stimulates protein biosynthesis. The administration of puromycin, a drug which blocks protein synthesis and, therefore, the thyroxine effect on protein synthesis, acutely reverses the hypermetabolism induced in rats by prior administration of thyroxine and restores the oxygen consumption of the thyrotoxic rats to the euthyroid level. The results suggest that a larger fraction of the total body basal oxygen consumption in hyperthyroidism is related to the process of protein synthesis than in the euthyroid state and that the calorigenic effect of thyroxine is secondary to its effect on protein synthesis.