Effects of acute ethanol on plasma and brain catecholamine levels in stressed and unstressed rats: evidence for an ethanol-stress interaction.

Plasma and brain catecholamines were measured during immobilization in rats which had or had not received ethanol (0.5 g/kg i.p.). Plasma levels in unstressed animals were unaffected by ethanol. Immobilization markedly increased circulating norepinephrine and epinephrine concentrations. Ethanol administered 15 min before immobilization significantly reduced the stress-induced increases in both plasma catecholamines, although individual differences in response were noted. In the brain, immobilization affected catecholamine levels in several regions, including reduced norepinephrine levels in the telencephalon and hypothalamus. Interestingly, norepinephrine levels in the telencephalon and hypothalamus were reduced to a similar degree by ethanol alone. However, ethanol administration before immobilization tended to reverse some of the stress-induced changes in brain catecholamine levels. Our data indicate that the effects of ethanol vary among rats and with the state of the subject. In general, ethanol does reduce the stress response in rats. They support the tension reduction hypothesis in man, where reduction in distress has been implicated in the etiology of alcoholism.