Central epinergic inhibition of corticosterone release in rat.

Drugs known to inhibit phenylethanolamine-N-methyltransferase (EC 2.1.1.28), the final enzyme in the epinephrine synthetic pathway were administered to rats and their effects on pituitary-arenal function studied. 2,3-Dichloro-a-methylbenzylamine (DCMB) produced dose-related increases in plasma corticosterone in basal and stressed rats. Evidence for the central nature of this tonic inhibitory effect of epinephrine was its continued presence in adrenal demedullated rats. 2-Chloro-3-trifluoromethyl-~-benzylamine (CTFMB) administration elevated plasma corticosterone and this effect was highly correlated to the decrease in hypothalamic epinephrine concentration in both sham operated and adrenal demedullated rats. These findings argue for tonic epinergic inhibition of pituitary-adrenal function.