Orally self-administered cocaine: reinforcing efficacy by the place preference method.

In three separate place preference conditioning (PPC) experiments, groups of rats were exposed to different modes of receiving cocaine: IP cocaine doses (7.5 mg/kg), PO cocaine self-administered bolus doses (15 mg/kg), and 1-h schedule-induced cocaine-solution drinking sessions (19.1 mg/kg). Oral cocaine self-administration of PO bolus and schedule induction took place in situations that preceded transfer into an apparatus for PPC sessions. Thus, the reinforcing efficacies of the pharmacological consequences of both oral cocaine self-administration methods were evaluated by a procedure separate from the self-administration behavior itself. The IP cocaine dose imposition and the two oral cocaine self-administration arrangements all resulted in dose-exposure conditions sufficient for the production of PPC. The serum and brain cocaine pharmacokinetics sufficient for the production of reinforcing efficacy were measured and related to previous data.