Effects of Ethanol In Vitro and In Vivo on the Release of Endogenous Catecholamines from Specific Regions of Rat Brain

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Abstract
Blocks of tissue from the hypothalamus, olfactory bulb or striatum of rats were incubated in vitro to study the basal and potassium-stimulated release of endogenous catecholamines. When ethanol (100-250 .mu.M) was added to these preparations in vitro no changes in release were observed. When ethanol (3.0 g .cntdot. kg-1) was injected i.p. in vivo, however, and 3,4-dihydroxyphenylethylamine (DA, dopamine) release was measured in vitro at various times after drug administration, significant increases in the basal release and decreases in the K stimulated release were observed in striatum and olfactory bulb. In striatum, these changes showed a more rapid onset and a longer duration than in olfactory bulb. In both brain regions, DA release did not differ from controls at 4-6 h after the ethanol injection, although blood ethanol concentrations remained elevated. The tissue may acquire acute functional tolerance to the drug. Similiar increases and decreases in the basal and the K-induced release of DA from striatal tissues were also found at 1 h after injection of a lower dose of ethanol (1.0 g .cntdot. kg-1). In terms of behavior, this lower dose of ethanol produced only mild intoxication and ataxia, in contrast to the loss of righting reflex following the higher dose.