NORADRENERGIC INVOLVEMENT IN ACUTE EFFECTS OF ETHANOL

Abstract

These studies were designed to determine several possibly related physiological correlates of an acute dose of ethanol. Male rats were injected with 0.5, 1.0 or 2.5 g/kg of ethanol i.p. and the accumulation of newly synthesized labeled norepinephrine [NE] (from 3H-tyrosine) and of labeled NE metabolites was examined in several brain regions. Ethanol treatment increased labeled NE and decreased NE metabolites in the hypothalamus, brainstem plus midbrain and telencephalon, without altering endogenous NE levels. A time course, selected on the basis of previous behavioral studies on the effects of ethanol on central noradrenergic neurons, disclosed that the accumulation of labeled NE metabolites was higher than that in saline-injected controls from 30-60 min after ethanol injection in the brainstem plus midbrain area, while 5-35 min levels were lower than those in control animals. Plasma corticosterone levels were highest 30 min after saline injection, while in the ethanol group (1 g/kg) steroids were highest 60 min after the injection. Body temperature was signficantly decreased only by the 2.5 g/kg dose of ethanol; the hypothermia became evident 50 min after an injection of this dosage. The brief hypermotile stage produced by a 1 g/kg dose of ethanol is possibly related to the increased synthesis and release of NE from central noradrenergic neurons.