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Abstract
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BACKGROUND: Aversion to the orosensory properties of concentrated ethanol solutions is often cited as a primary barrier to initiation of drinking and may contribute to abstention. These aversive properties include gustatory processes which encompass both bitter-like taste qualities and trigeminal-mediated irritation. Chronic-intermittent ethanol access (CIA) results in substantial and persistent increases in ethanol consumption, but the degree to which this facilitation involves sensory responding to ethanol and other bitter stimuli is currently undetermined.
METHODS: Long-Evans rats were given brief-access licking tests designed to examine the immediate, taste-guided assessment of the palatability of ethanol and quinine solutions. Rats were assessed once in a naïve state and again following previous brief-access exposure, or following four weeks of CIA. The relationship between the sensitivity to the aversive orosensory properties of ethanol and quinine following ethanol access and the impact of antecedent quinine exposure on the acceptance of ethanol were determined in two parallel studies.
RESULTS: Both brief-access to ethanol and four-week CIA resulted in substantial rightward shifts in the concentration-response function of brief-access ethanol licking indicating that ethanol exposure increased acceptance of the taste of ethanol. The initial sensitivity to the aversive orosensory properties of ethanol and quinine were positively correlated in naïve rats, such that rats that were initially more accepting of quinine were also more accepting of ethanol. Rats that sampled quinine immediately prior to tasting ethanol exhibited successive positive contrast in that they were more accepting of highly concentrated ethanol, relative to a water-control group.
CONCLUSIONS: Increased ethanol acceptance following exposure is, at least in part, facilitated by a decrease in its aversive sensory properties. Both long and short term access increases the palatability of the taste of ethanol in brief-access licking tests. Moreover, the sensitivity to the bitterness of quinine was predictive of acceptance of ethanol indicating some commonality in the sensory mechanisms that mediate the initial acceptance of the two stimuli. Accordingly, immediate prior exposure to quinine results in increased acceptance of ethanol suggesting that successive positive contrast between oral stimuli may contribute to increased alcohol consumption. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
Language: en |