Effects of Cagemate Gender and the Cagemate's access to ethanol on ethanol and water intake of the proximal male or the proximal female CD-1 mouse

The effects of social stimulation on ethanol drinking in humans may depend on the gender of the drinker, the gender of the social stimulus, and the availability of ethanol provided to the social stimulus. The present study employed the Proximal Cagemate Drinking (PCD) Procedures to evaluate the effects of the gender of the social stimulus Cagemate mouse and the effects of providing ethanol to the Cagemate mouse on the drinking of ethanol and water by the male or female CD-1 Drinker mouse. Twelve groups of subjects were arranged in a 3 × 2 × 2 factorial design with 3 levels of Cagemate Gender (Male vs. Female vs. None), 2 levels of Drinker Gender (Male vs. Female), and 2 levels of Cagemate Ethanol (Ethanol vs. No Ethanol). In the 8 groups assigned to social housing conditions, each Drinker mouse was housed with a Cagemate mouse on opposite sides of a clear plastic shoebox cage equipped with a clear plastic barrier that divided the cage lengthwise into 2 equal compartments. Six groups of Drinkers and 4 groups of Cagemates were provided with continuous access to 2 bottles (ethanol vs. water), while the 4 groups of Cagemates in the No Ethanol condition were provided with 2 bottles containing water. Results revealed that providing the Cagemate with ethanol elevated ethanol intake and ethanol preference but reduced water intake in Drinkers in Other-Gender Pairings (Male Drinker-Female Cagemate or Female Drinker-Male Cagemate) relative to Drinkers in Same-Gender Pairings (Male Drinker-Male Cagemate or Female Drinker-Female Cagemate). In contrast, when the Cagemate was not provided with access to ethanol, the opposite effects were observed. These novel PCD procedures reveal that the gender of the Cagemate and the Cagemate's access to ethanol influenced ethanol drinking in proximal-housed CD-1 Drinker mice.