Adrenal phenylethanolamine-N-methyltransferase activity in the young rat: influence of thyroid hormones and insulin-induced hypoglycemia.

The postnatal evolution of adrenal phenylethanolamine-N-methyltransferase (PNMT) activity is slightly accelerated by hypothyroidism and slowed by hyperthyroidism. In 14-day-old rats a single stimulation of the adrenals by insulin-induced hypoglycemia does not lead to any change in enzymatic activity. If the stimulation is repeated for 4 days, it leads to a net increase in adrenal PNMT activity in the control rats, while no increase occurs in hypo- or hyperthyroid animals.