Social Contact Reinforces Cocaine Self-Administration in Young Adult Male Rats: The Role of Social Reinforcement in Vulnerability to Drug Use

Abstract

Drug-using peers are recognized as a leading factor influencing drug use among adolescents and young adults. One mechanism by which peers influence drug use is by providing social reinforcement for using drugs. Social reinforcement may be provided in multiple ways, including by making social contact contingent on drug use (i.e., an individual must use drugs to gain/maintain access to a peer). The purpose of this study was to develop a preclinical model in which intravenous cocaine self-administration was positively reinforced by access to a social partner. Young adult male rats were trained to self-administer cocaine in operant conditioning chambers with a guillotine door that could be opened to an adjacent compartment housing either a social partner or a non-social stimulus. Once cocaine self-administration was established, the guillotine door was activated, and cocaine intake was reinforced by brief access to either a social (age- and sex-matched peer) or non-social (black-and-white athletic sock) stimulus. Contingent access to a social partner rapidly increased cocaine self-administration. Total cocaine intake was 2- to 3-fold greater in rats assigned to the social versus non-social condition across a 100-fold dose range. Cocaine intake rapidly increased when rats in the original non-social group were later provided with social partners, whereas cocaine intake resisted change and remained elevated when rats in the original social group had their partners removed. These data indicate that contingent access to a social partner increases drug intake and suggest that social reinforcement may represent a vulnerability factor that is particularly resistant to psychosocial interventions.

A network-based analysis detects cocaine-induced changes in social interactions in Drosophila melanogaster

“…A recent rodent study shows that social interactions change the activity of specific dopaminergic circuits that control drug craving, suggesting that social interaction has a reinforcing influence on addictive behaviors [ 62 , 63 ]. The brain of Drosophila is comprised of some 150.000 neurons, of which 127 per hemisphere are dopaminergic (DA) and 80 serotonergic (5-HT) [ 64 , 65 ].…”

Wistar rats choose alcohol over social interaction in a discrete-choice model

“…This could be explained by the fact that, in addition to its effect on social interaction, social isolation can also act as a stressor, promoting drug selfadministration and alcohol-related behaviors [38][39][40][41]. Moreover, it has been reported that the presence of a partner rat during drug self-administration acts as a reinforcer, when presented as a consequence of pressing for the drug, promoting thus drug intake [42]. In our experimental settings, however, choosing alcohol meant that the opportunity for social interaction was dismissed at the expense of the drug, potentially suggesting a lower reinforcing value of social interaction when presented with alcohol.…”

Effect of social instability stress in adolescence or adulthood on sensitivity to sucrose concentration in a social context in male and female Long‐Evans rats

“…In addition, the social context can alter behavioral responding to nonsocial rewards. For example, there are several reports of protective effects of social reward against self-administration of psychostimulants and opiates (Venniro et al, 2018(Venniro et al, , 2019, and cocaine self-administration was increased by contingent access to a social peer (Smith et al, 2021). The presence of a peer influences adolescent humans as well.…”