Abstract.
Rationale: Several reports have demonstrated that the γ-aminobutyric acid (GABA)B agonist baclofen attenuates the reinforcing effects of cocaine in rats, and recent evidence indicates that it might have a similar effect on heroin self-administration. Objectives: The specific GABAB receptor antagonist CGP56433A was used to further evaluate the involvement of GABAB receptors in the baclofen-induced suppression of cocaine and heroin self-administration. Methods: In the first series of experiments, dose–response curves were generated to examine the effect of CGP56433A (0.6, 1.0, or 1.8 mg/kg, i.p.) on cocaine (1.5 mg/kg per injection) and heroin (25 µg/kg per injection) self-administration reinforced under a fixed-ratio (FR1) or progressive ratio (PR) schedule. Separate sets of experiments then examined the effect of the co-administration of CGP56433A and baclofen on responding for cocaine or heroin under both schedules. Results: Pretreatment with CGP56433A had no effect on cocaine or heroin self-administration, while baclofen dose dependently reduced responding for both cocaine and heroin under both the FR1 and PR schedule. CGP56433A (1.8 mg/kg) blocked the effect of baclofen on cocaine but not on heroin self-administration. Conclusion: The specific GABAB antagonist CGP56433A attenuated the effect of baclofen on cocaine self-administration, suggesting that GABAB receptors are critical in mediating the anti-cocaine effect of baclofen. In combination with other studies, the data demonstrate that the susceptibility of baclofen and other GABAB agonists to receptor blockade depends on the behavioral response being studied. Whether this indicates different receptor mechanisms are involved (e.g., pre- versus post-synaptic effects or differential receptor reserve) remains to be determined.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
Author information
Authors and Affiliations
Additional information
Electronic Publication
Rights and permissions
About this article
Cite this article
Brebner, K., Froestl, W. & Roberts, D.C. The GABAB antagonist CGP56433A attenuates the effect of baclofen on cocaine but not heroin self-administration in the rat. Psychopharmacology 160, 49–55 (2002). https://doi.org/10.1007/s00213-001-0952-7
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s00213-001-0952-7