Effect of spontaneous ingestion of ethanol on brain dopamine metabolism.

The effect of ethanol, either administered by gavage or voluntarily ingested, on brain dopamine (DA) metabolism was studied in alcohol-preferring and alcohol non-preferring rats. In alcohol non-preferring rats ethanol administration (2 g/kg) increased 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) and reduced DA levels in the caudate nucleus and olfactory tubercle but was ineffective in the medial prefrontal cortex. In alcohol-preferring rats ethanol effect was greater than in non-preferring animals and ethanol influenced DA metabolism also in the medial prefrontal cortex. The effect of voluntary ethanol ingestion was studied in alcohol-preferring rats trained to consume their daily fluid intake within 2 hrs. Voluntary ingestion of ethanol (3.1 +/- 0.7 g/kg in 1 hr) increased DA metabolites and reduced DA levels in the caudate nucleus, olfactory tubercle and medial prefrontal cortex. The results suggest that voluntary ethanol ingestion increases the release of DA from nigro-striatal and meso-limbic DA neurons.