Ethanol Induces Conditioned Social Preference in Male Mice

Abstract

Background Affiliative social interactions promote alcohol consumption, and alcohol also promotes affiliative behavior. Furthermore, for most species, moderate doses of ethanol (EtOH) and social affiliation are each rewarding. However, animal studies of drug and EtOH reward typically test individuals in isolation. To address social dimensions of EtOH reward, the present study tested EtOH-induced conditioned social preference in male C57BL/6 mice with (ORCHX+T) and without (ORCHX) testosterone. Methods ORCHX+T males received EtOH (0, 1, 2 or 3g/kg) ip and were paired 4x for 30 min each with 1 of 2 stimulus males: with the CS-stimulus male after saline injection, and with the CS+ male following EtOH. After pairing, time spent with CS+ and CS− males was measured in a 10 min test. Results ORCHX+T test males showed conditioned preference for the CS+ male in response to 3 g/kg EtOH (change in preference: +71.3±30.0 sec/10 min, p<0.05), but not for 0, 1 or 2g/kg. By contrast, ORCHX males did not demonstrate conditioned preference for 3g/kg EtOH (+16.0±24.3 sec/10 min, p>0.05). In separate groups of mice, stimulus males (IS+) received EtOH during pairing to determine if test mice prefer another intoxicated mouse. Both ORCHX+T and ORCHX test mice showed an increase in preference score for the IS+ mouse (ORCHX+T: +68.1±24.0 sec, ORCHX: +58.9±19.6 sec, p<0.05). Conclusions These data demonstrate that EtOH promotes social preference in male mice, as it does in females. Testosterone enhances this effect.

Social housing conditions and oxytocin and vasopressin receptors contribute to ethanol conditioned social preference in female mice

“…In WT(wt) females, repeated pairing with 2 g/kg ethanol induced a significant increase in preference for the CS+ stimulus female (p<0.05), as in our previous study of C57Bl/6 female mice [16]. Preference scores for the CS+ stimulus female averaged −12.3±23.1 seconds during pre-test (mean±SEM) and 103.1±22.6 seconds after pairing, a +115.4±22.0 second increase.…”

“…Furthermore, meadow and prairie voles drink more ethanol in a social condition than in a non-social setting [15]. Our laboratory has used a conditioned social preference (CSP) model to explore conditioned reinforcing effects of an ethanol-associated stimulus [16, 17]. CSP is derived from conditioned place preference (CPP), a well-established model to study the motivational effects of drugs and other unconditioned stimuli (US) [18].…”

“…In CSP, the CS+ and CS− are unfamiliar stimulus mice. Using this model, male [16] and female mice [17] show a conditioned preference for the CS+ stimulus female with whom they have been intoxicated previously. Specifically, female mice show CPP [19] and CSP [17] in response to 2 g/kg ethanol, the dose used in the present study.…”