Social reward-conditioned place preference: A model revealing an interaction between cocaine and social context rewards in rats

Abstract

A recent thrust in drug abuse research is the influence of social interactions on drug effects. Therefore, the present study examined conditioned place preference (CPP) as a model for assessing interactions between drug and social rewards in adolescent rats. Parameters for establishing social reward-CPP were examined, including the number of conditioning sessions/day (1 or 2), the total number of sessions (2, 4, or 16), and the duration of sessions (10 or 30 min). Subsequently, the effects of cocaine or dextromethorphan on social reward-CPP and play behavior were examined. The results demonstrate that social reward-CPP (i.e., preference shift for an environment paired previously with a rat) was similar using either 1 or 2 conditioning sessions/day and either 10 or 30 min sessions; however, social reward-CPP increased as the number of social pairings increased. Additionally, a low dose of cocaine (2 mg/kg, IP) and a low number of social pairings (2 pairings) failed to produce CPP when examined alone, but together produced a robust CPP, demonstrating an interaction between these rewards. The non-rewarding drug, dextromethorphan (30 mg/kg, IP), failed to enhance social reward-CPP, suggesting that drug-enhanced social reward-CPP is specific to rewarding drugs. Surprisingly, there was no relationship between play behaviors and preference shift in drug-naïve animals. Furthermore, cocaine inhibited play behavior despite enhancing social reward-CPP, suggesting that aspects of social interaction other than play behavior likely contribute to social reward. The findings have important implications for understanding the influence of social context on cocaine reward during adolescence.

Female juvenile play elicits Fos expression in dopaminergic neurons of the VTA.

“…However, that possibility still highlights the importance of these dopaminergic neurons for female play. Taken together, these data point to a likely role for the VTA in the neural circuitry mediating play in females, and is not a surprising finding given that play is a reinforcing behavior (Calcagnetti & Schechter, 1992;Douglas et al, 2004;Thiel et al, 2008;Trezza et al, 2009). The mesolimbic dopamine system is important for the reinforcement of many behaviors, including other social behaviors such as reproduction, social bonding, and parenting (Aragona et al, 2003;Balfour et al, 2004;Charlier, Ball, & Balthazart, 2005;Hansen et al, 1991;Numan et al, 2005), and dopamine release into the NAcc and/or prefrontal cortex as female rats play may contribute to the maintenance of play motivation throughout the juvenile period.…”

Contrasting Roles of Dopamine and Noradrenaline in the Motivational Properties of Social Play Behavior in Rats

“…At first glance, these findings suggest that behaviors other than social play serve as a reinforcer after psychostimulant treatment (Thiel et al, 2008). For example, rats treated with MDMA show increases in passive social behavior (Thompson et al, 2007), and rewarding properties of the tactile aspects of social interaction have indeed been demonstrated (Kummer et al, 2011).…”

“…The pleasurable properties of social play behavior have previously been studied using place conditioning, in which young rats develop a preference for an environment associated with social play if the play encounter is perceived as pleasurable (Calcagnetti and Schechter, 1992;Crowder and Hutto, 1992;Douglas et al, 2004;Thiel et al, 2008;Trezza et al, 2009a;Peartree et al, 2012). However, the incentive motivational properties of social play have only been sporadically investigated in the past (Mason et al, 1962;Humphreys and Einon, 1981;Normansell and Panksepp, 1990).…”

Individual Differences and Social Influences on the Neurobehavioral Pharmacology of Abused Drugs

“…One interpretation of these findings is that methylphenidate decreases social reward, perhaps by reducing play behavior . However, nicotine and cocaine also reduce play behavior, yet enhance social CPP (Thiel et al, 2008(Thiel et al, , 2009), suggesting that a reduction in play does not necessarily result in an inhibitory interaction between all stimulants and social reward. Further research is needed to investigate whether drug x social reward interactions depend on the drug or environmental determinants that vary across studies.…”

“…Social reward interacts synergistically with both cocaine and nicotine to produce CPP in adolescent male rats since conditioning parameters that fail to support social or drug reward when given alone can produce CPP when given together (Thiel et al, 2008(Thiel et al, , 2009. Social reward competes with drug reward in young male rats since pairing a conspecific with one compartment and cocaine with the other compartment fails to produce CPP, even though either reward alone produces CPP (Fritz et al, 2011b,d).…”