Intermittent exposure to a social stimulus enhances ethanol drinking in rats

Abstract

The present experiment evaluates the effects of intermittent exposure to a social stimulus on ethanol and water drinking in rats. Four groups of rats were arranged in a 2x2 factorial design with 2 levels of Social procedure (Intermittent Social vs Continuous Social) and 2 levels of sipper Liquid (Ethanol vs Water). Intermittent Social groups received 35 trials per session. Each trial consisted of the insertion of the sipper tube for 10 s followed by lifting of the guillotine door for 15 s. The guillotine door separated the experimental rat from the conspecific rat in the wire mesh cage during the 60 s inter-trial interval. The Continuous Social groups received similar procedures except that the guillotine door was raised during the entire duration of the session. For the Ethanol groups, the concentrations of ethanol in the sipper [3, 4, 6, 8, 10, 12, 14, and 16% (vol/vol)] increased across sessions, while the Water groups received 0% ethanol (water) in the sipper throughout the experiment. Both Social procedures induced more intake of ethanol than water. The Intermittent Social procedure induced more ethanol intake at the two highest ethanol concentration blocks (10-12% and 14-16%) than the Continuous Social procedure, but this effect was not observed with water. Effects of social stimulation on ethanol drinking are discussed.

Characterizing conditioned reactivity to sequential alcohol-predictive cues in well-trained rats

“…Except for Tomie and colleagues (2004, 2006, 2007), preclinical researchers modeling the appetitive conditioning effects of human alcohol consumption in rodents do not typically verify that ingested alcohol can be detected in blood. If alcohol can be detected in the blood, then it is reaching the brain and it can be argued that conditioned behavior in these rodent models stems from some action of alcohol on the brain, like we believe it does in humans.…”

The Effects of Proximal and Distal Social Stimulation on Ethanol Intake in Male and Female CD-1 Mice

“…The stimulating effects of direct proximal social interactions on ethanol intake have also been reported in a number of rodent species, including rats [6,7,8,9,10,11,12,13], mice [14,15,16], and prairie voles [17,18]. It should be noted that several early investigations employing animal subjects evaluated the effects of social stimulation by comparing ethanol consumption in isolation-housed versus group-housed rodents, and found little evidence of social stimulation of ethanol drinking [7,8,16,19,20].…”

“…During experimental days 1-5, the drinker mice and the cagemate mice as well as the distal group-housed mice were provided with access to ethanol, the vol/vol. concentration of ethanol in the sipper was increased daily in 2% increments from 2% to 10%, and then maintained at 10% for the remaining seven days of the study (experimental days [6][7][8][9][10][11][12]. This schedule of ascending ethanol concentrations, with a maximum ethanol concentration of 10%, was similar to the schedule of ethanol concentrations employed in earlier investigations of intersex effects in rats [11] and in prairie voles [26].…”

Translational approach to understanding momentary factors associated with alcohol consumption

“…Similar results were obtained by providing rats with opportunities for social interaction, demonstrating that alcohol consumption was higher when access to alcohol was given combined with the opportunity for social interaction (Tomie, Gittleman, Dranoff, & Pohorecky, 2005). However, when rats were given continuous access to social interaction, alcohol intake was lower compared to rats that were provided with intermittent access opportunities (Tomie, Lewis, Curiotto, & Pohorecky, 2007), indicating that social communication‐related factors can affect probability of alcohol use. That social stimuli function as contextual cues in rats has also been demonstrated by the study of Browning and Shahan (2018).…”