Differential vulnerability to the punishment of cocaine related behaviours: effects of locus of punishment, cocaine taking history and alternative reinforcer availability.

BACKGROUND

The availability of alternative reinforcement has been shown to reduce drug use, but it remains unclear whether it facilitates a reduction or cessation of drug seeking or taking.

OBJECTIVES

We compared the effects of punishment of cocaine seeking or taking behaviour after brief or extended cocaine-taking histories when behavioural reallocation was facilitated or not by making available an alternative ingestive reinforcer (sucrose).

METHODS

In the first experiment, punishment of either seeking or taking responses was introduced immediately after training on the seeking-taking chained schedule. In the second experiment, punishment of cocaine seeking was introduced after 12 additional days of either 1 or 6 h daily access to cocaine self-administration. In both experiments, beginning 1 week before the introduction of punishment, a subset of rats had concurrent nose poke access to sucrose while seeking or taking cocaine.

RESULTS

The presence of an alternative source of reinforcement markedly facilitated behavioural reallocation from punished cocaine taking after acquisition. It also facilitated punishment-induced suppression of cocaine seeking after an extensive cocaine self-administration history likely by prompting goal-directed motivational control over drug use. However, a significant proportion of rats were deemed compulsive-maintaining drug use after an extensive cocaine history despite the presence of abstinence-promoting positive and negative incentives.

CONCLUSION

Making available an alternative reinforcer facilitates disengagement from punished cocaine use through at least two different processes but remains ineffective in a subpopulation of vulnerable animals, which continued to seek cocaine despite the aversive consequence of punishment and the presence of the alternative positive reinforcer.