Quitting together: Effects of group extinction on nicotine reinstatement.

Zebrafish exhibit social behaviours, such as shoaling, making them an attractive model for investigating how social interactions influence behaviour. Here, we assessed the rewarding effects of nicotine on zebrafish shoaling behaviour, examined whether the shoal influences the rewarding properties of nicotine. In this study, we have developed a nicotine extinction and reinstatement protocol to later assess how the presence of conspecifics can alter the way nicotine reinstatement takes place. We found that visual interaction with conspecifics during the extinction phase of a reinstatement paradigm does not disrupt the drug-environment association, whereas conspecific presence during the reinstatement challenge abolishes nicotine seeking behaviour. According to these results, nicotine appears to be strong enough to elicit sustained preference despite the presence of conspecifics during extinction but not so strong as to circumvent the distracting factor that arises when conspecifics are present during the reinstatement challenge. Interestingly, when animals undergo grouped extinction in the same tank, implying direct interaction and not only visual social stimuli, nicotine reinstatement is abolished. Our results appear to indicate that the mere view of conspecifics is not enough to counterbalance an appetitive memory of a drug of abuse such as nicotine and that being part of a group is much more disruptive to said memory in a gregarious animal such as the zebrafish.