title: Binge drinking in alcohol-preferring sP rats at the end of the nocturnal period.
abstract: Sardinian alcohol-preferring (sP) rats have been selectively bred for high alcohol preference and consumption using the standard 2-bottle "alcohol (10%, v/v) vs. water" choice regimen with unlimited access; under this regimen, sP rats daily consume 6-7 g/kg alcohol. The present study assessed a new paradigm of alcohol intake in which sP rats were exposed to the 4-bottle "alcohol (10%, 20%, and 30%, v/v) vs. water" choice regimen during one of the 12 h of the dark phase of the daily light/dark cycle; the time of alcohol exposure was changed daily in a semi-random order and was unpredictable to rats. Alcohol intake was highly positively correlated with the time of the drinking session and averaged approximately 2 g/kg when the drinking session occurred during the 12th hour of the dark phase. Alcohol drinking during the 12th hour of the dark phase resulted in (a) blood alcohol levels averaging approximately 100 mg% and (b) severe signs of alcohol intoxication (e.g., impaired performance at a Rota-Rod task). The results of a series of additional experiments indicate that (a) both singular aspects of this paradigm (i.e., unpredictability of alcohol exposure and concurrent availability of multiple alcohol concentrations) contributed to this high alcohol intake, (b) alcohol intake followed a circadian rhythm, as it decreased progressively over the first 3 h of the light phase and then maintained constant levels until the beginning of the dark phase, and (c) sensitivity to time schedule was specific to alcohol, as it did not generalize to a highly palatable chocolate-flavored beverage. These results demonstrate that unpredictable, limited access to multiple alcohol concentrations may result in exceptionally high intakes of alcohol in sP rats, modeling - to some extent - human binge drinking. A progressively increasing emotional "distress" associated to rats' expectation of alcohol might be the neurobehavioral basis of this drinking behavior.
authors.affiliation: Neuroscience Institute, National Research Council of Italy, Section of Cagliari, S.S. 554, km. 4,500, I-09042 Monserrato (CA), Italy. Electronic address: colomb@unica.it.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Colombo
authors.affiliation: Neuroscience Institute, National Research Council of Italy, Section of Cagliari, S.S. 554, km. 4,500, I-09042 Monserrato (CA), Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Maccioni
authors.affiliation: Neuroscience Institute, National Research Council of Italy, Section of Cagliari, S.S. 554, km. 4,500, I-09042 Monserrato (CA), Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Acciaro
authors.affiliation: Neuroscience Institute, National Research Council of Italy, Section of Cagliari, S.S. 554, km. 4,500, I-09042 Monserrato (CA), Italy.
authors.forename: Carla
authors.initials: C
authors.lastname: Lobina
authors.affiliation: Neuroscience Institute, National Research Council of Italy, Section of Cagliari, S.S. 554, km. 4,500, I-09042 Monserrato (CA), Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Loi
authors.affiliation: Neuroscience Institute, National Research Council of Italy, Section of Cagliari, S.S. 554, km. 4,500, I-09042 Monserrato (CA), Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Zaru
authors.affiliation: Neuroscience Institute, National Research Council of Italy, Section of Cagliari, S.S. 554, km. 4,500, I-09042 Monserrato (CA), Italy.
authors.forename: Mauro A M
authors.initials: MA
authors.lastname: Carai
authors.affiliation: Neuroscience Institute, National Research Council of Italy, Section of Cagliari, S.S. 554, km. 4,500, I-09042 Monserrato (CA), Italy.
authors.forename: Gian Luigi
authors.initials: GL
authors.lastname: Gessa
mesh_terms: D000428:Alcohol Drinking / Q000523:psychology*; D000435:Alcoholic Intoxication / Q000523:psychology*; D000818:Animals; D002755:Choice Behavior; D002940:Circadian Rhythm; D004327:Drinking Behavior; D000431:Ethanol / Q000097:blood; D008297:Male; D051381:Rats
chemical_list: D000431:Ethanol
keywords: Experimental model of binge drinking; Limited and unpredictable access to alcohol; Sardinian alcohol-preferring (sP) rats; Time schedule of alcohol drinking