Importance of delta opioid receptors in maintaining high alcohol drinking.

We have previously reported that naloxone, a nonspecific opioid receptor antagonist, suppresses alcohol but not water consumption by male rats that have been genetically selected for high voluntary alcohol drinking. However, the identity of the specific opioid receptor subtype that may mediate alcohol drinking is not known. This paper reports that a selective delta opioid receptor antagonist is as effective as naloxone in suppressing alcohol consumption and that an enkephalinase inhibitor, which potentiates the action of endogenous enkephalins, increases alcohol intake.

Naloxone attenuates voluntary ethanol intake in rats selectively bred for high ethanol preference.

The effect of naloxone on voluntary ethanol intake was examined in rats which were selectively bred for oral ethanol preference (High Alcohol Drinking or HAD line). Rats of the HAD line were treated with naloxone in doses of 0.05-18.

Differences in response to the aversive properties of ethanol in rats selectively bred for oral ethanol preference.

A conditioned taste aversion (CTA) paradigm was used to determine whether aversion to the pharmacological effects of ethanol, apart from orosensory cues, can contribute to genetic differences in voluntary ethanol consumption. Four doses of ethanol, administered IP, were paired with the consumption of a 0.1% saccharin solution in rats from the alcohol-preferring (P) and alcohol-nonpreferring (NP) lines.

Naloxone attenuation of voluntary alcohol consumption.

The effect of naloxone on voluntary alcohol consumption was examined in two lines of rats which have recently been selectively bred for oral alcohol preference (High Alcohol Drinking or HAD line) or aversion (Low Alcohol Drinking or LAD line). Genetic differences in brain met-enkephalin content were examined in two additional lines of rats which have been genetically selected for oral alcohol preference (Alcohol-Preferring or P line) or aversion (Alcohol-Nonpreferring or NP line).