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

Background. Proximal and distal social stimulation increase ethanol drinking in humans. Purpose. Our study evaluated the effects of proximal and distal social stimulation on home-cage ethanol drink- ing in mice.Study design. Proximal cagemate drinking (PCD) proce- dures use a clear plastic barrier to separate the drinker mouse from the proximal cagemate mouse, to evaluate home-cage drinking of 10% ethanol and water. Eight groups of CD-1 mice were arranged in a 2 × 2 × 2 factorial design with two levels of sex of drinker (male vs. female), two levels of sex of cagemate (male vs. female), and two levels of distal group-housed mice in the colony room (present vs. absent). Results. Distal group-housed mice, located outside of the home cage, stimulated ethanol drinking in female drinkers and did so regardless of the sex of their proximal cagemate. This effect was observed in the male drinker but only when housed with a proximal male cagemate. Conclusion. This study provides the first report of distal social stimu- lation of ethanol drinking in mice. The distal social stimulation effect, like the effects of proximal social stimulation, was more pronounced in female drinkers.