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Psychopharmacology (Berl). 2015 Oct;232(19):3585-95. doi: 10.1007/s00213-015-4010-2. Epub 2015 Jul 7.

Elevated reinforcing and motivational properties of alcohol at the end of the nocturnal period in sP rats.

Author information

1
Neuroscience Institute, Section of Cagliari, National Research Council of Italy, S.S. 554, km. 4,500, I-09042, Monserrato (CA), Italy.

Abstract

RATIONALE:

Sardinian alcohol-preferring (sP) rats displayed high sensitivity to time schedule and consumed intoxicating amounts of alcohol during the last portion of the dark phase of the light/dark cycle when exposed to daily drinking sessions of 1 h, with concurrent availability of multiple alcohol concentrations and unpredictability of time of alcohol access.

OBJECTIVES:

The present study investigated whether sensitivity of sP rats to time schedule extended to operant procedures of alcohol self-administration.

METHODS:

In experiment 1, three different alcohol solutions (10, 20, and 30%, v/v) were concurrently available under a fixed ratio 4 schedule of reinforcement and with unpredictable time schedule; water was available uncontingently. Experiments 2 and 3 assessed the sensitivity of the motivational properties of alcohol to time schedule; rats were exposed to (a) self-administration sessions under the progressive ratio (PR) schedule of reinforcement and (b) sessions of alcohol seeking under the extinction responding (ER) schedule.

RESULTS:

In experiment 1, number of lever responses and amount of self-administered alcohol were positively correlated with time of alcohol access during the dark phase. When the self-administration session occurred at the first and latest hours of the dark phase, the amount of self-administered alcohol averaged 0.95-1.0 and 1.55-1.65 g/kg, respectively. In experiments 2 and 3, values of breakpoint and ER for alcohol were approximately 50% higher when the sessions occurred at the last than first hour of the dark phase.

CONCLUSIONS:

The reinforcing and motivational properties of alcohol were sensitive to time schedule and stronger at the end of the dark phase.

PMID:
26146016
PMCID:
PMC4561583
DOI:
10.1007/s00213-015-4010-2
[Indexed for MEDLINE]
Free PMC Article

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