Biochemical evidence for activation of specific monoamine pathways by ethanol.

The effects of an acute intraperitoneal (IP) low (0.5 g/kg) or high (2.5 g/kg) dose of ethanol on the contents of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in 7 selected CNS regions of the rat were examined after 15, 30 and 60 minutes. The IP administration of 0.5 g/kg ethanol produced blood alcohol concentrations (BACs) of 41 +/- 4, 40 +/- 4 and 15 +/- 1 mg% (N = 8 each) after 15, 30 and 60 minutes, respectively. This low dose of ethanol did not alter the levels of DA, DOPAC, HVA, 5-HT and 5-HIAA in any of the 7 CNS regions at any of the time points examined. The dose of 2.5 g/kg ethanol produced BACs of 254 +/- 26, 268 +/- 20 and 282 +/- 10 mg% (N = 8 each) after 15, 30 and 60 minutes, respectively. This high dose of ethanol did not alter the contents of DA and 5-HT in any of the regions examined at any of the times, except for a 30% increase in the content of DA in the posterior striatum after 60 minutes. The administration of 2.5 g ethanol/kg elevated the levels of DOPAC and/or HVA 25 to 70% over saline control values in the (a) nucleus accumbens (ACC) and hypothalamus (HYPO) after 15, 30 and 60 minutes, and (b) posterior striatum (PSTR), lateral septal nucleus (LSN) and frontal cortex (FCTX) after 60 minutes. The contents of DOPAC and/or HVA were not altered by the high dose of ethanol in either the thalamus or olfactory bulbs.(ABSTRACT TRUNCATED AT 250 WORDS)