Ethanol-induced CTA mediated by acetaldehyde through central catecholamine activity.

The possible involvement of catecholamines (CA) in the mediation of acetaldehyde's conditioned taste aversion (CTA) was examined by testing the effects of alpha-methyl-para-tyrosine (AMPT, a tyrosine hydroxylase inhibitor) on the CTAs produced by acetaldehyde. AMPT blocked the acquisition of the CTA normally produced by a low dose of acetaldehyde (0.2 g/kg), but had no significant effect on CTA produced by a high dose of acetaldehyde (0.3 g/kg). In a second study, acetaldehyde's role in the CTA produced by ethanol was investigated using the pre-exposure conditioned taste aversion paradigm. Pre-exposure to acetaldehyde (both doses) blocked the ethanol CTAs but when pre-exposure with acetaldehyde was coupled with AMPT, only the larger dose of acetaldehyde blocked the ethanol aversion. These results suggest that while the CTA to the low dose of acetaldehyde may be primarily central and catecholamine-mediated, the mechanism underlying the high dose CTA is probably peripheral and emetic in nature. These findings support the conclusion that acetaldehyde may be mediating many of the actions of ethanol.