The expression of an alcohol deprivation effect in the high-alcohol-drinking replicate rat lines is dependent on repeated deprivations.

BACKGROUND

The alcohol deprivation effect (ADE) is a temporary increase in the ratio of alcohol/total fluid intake and voluntary intake of ethanol (EtOH) solutions over baseline drinking conditions when EtOH access is reinstated after a period of alcohol deprivation. The ADE has been posited to be an animal model for alcohol craving. In the current study, we examined the effects of initial deprivation length and number of deprivation exposures on the ADE in the replicate lines of the high-alcohol-drinking (HAD) rats.

METHODS

Adult male HAD-1 and HAD-2 rats received 24 hr free-choice access to 10% (v/v) EtOH and water for 6 weeks. Rats were then assigned to groups deprived of EtOH for 0 (control), or 2 to 8 weeks. All deprived groups were then given 24 hr access to EtOH for 2 weeks before being deprived of EtOH for another 2 weeks. This cycle of 2 weeks of access and 2 weeks of deprivation was carried out for a total of four deprivations.

RESULTS

After the initial EtOH deprivation period, EtOH consumption in HAD-1 and HAD-2 rats returned to baseline levels but failed to exhibit either an early onset ADE (initial 2 hr) or prolonged ADE (24 hr). An ADE was observed in two of the four deprived groups for the HAD-1 rats (2 week and 6 week groups) and in all deprived groups for the HAD-2 rats after a second deprivation, and in all deprived groups of both lines after a third deprivation. In the HAD-2 line, but not in the HAD-1 line, the duration of the ADE was prolonged into the second reinstatement day after the fourth deprivation.

CONCLUSIONS

The expression of an ADE was observed only after repeated deprivation periods in the HAD lines. The duration of the ADE was prolonged in the HAD-2 line, but not in the HAD-1 line, with repeated deprivations, which suggests a dissociation between selection for alcohol preference and the effects of repeated deprivations on the duration of the ADE.