Fig. 4.
Alcohol intake in Sardinian alcohol-preferring (sP) rats exposed to 12 consecutive daily 1-h drinking sessions under four different experimental conditions: (a) 4-bottle “alcohol (10%, 20%, and 30%, v/v) vs. water” choice regimen with drinking sessions occurring always at the 1st hour of the dark phase of the daily light/dark cycle (“1st-Hour/Fixed”) (panels A and C); (b) 4-bottle “alcohol (10%, 20%, and 30%, v/v) vs. water” choice regimen with drinking sessions occurring always at the 12th hour of the dark phase (“12th-hour/Fixed”) (panels A and D); (c) 4-bottle “alcohol (10%, 20%, and 30%, v/v) vs. water” choice regimen with drinking session occurring during one of the 12 h of the dark phase, changed daily in a semi-random order and unpredictable to rats (“4-Bottle/Unpredictable”) (panels B–D); (d) 2-bottle “alcohol (10%, v/v) vs. water” choice regimen with drinking session occurring during one of the 12 h of the dark phase, changed daily in a semi-random order and unpredictable to rats (“2-Bottle/Unpredictable”) (panel B). Alcohol intake is expressed in grams of pure alcohol per kg body weight. Arrows indicate values collected on the day when both rat groups were concurrently exposed to alcohol during the 1st (panel C) and 12th (panel D) hour of the dark phase. Each point is the mean ± SEM of n = 8 rats.