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The Thai Journal of Pharmaceutical Sciences

Abstract

Introduction: Kratom (Mitragyna speciosa Korth) is currently used as an alternative for the self-treatment of pain and management of opioid dependence and withdrawal. Due to the opioid-like effect of the plant’s active alkaloid, mitragynine (MG), the evaluation of its ability to maintain self-administration in animal models of opioid dependence appears to be great significance. Objectives: Here, the ability of MG to cross-substitute to the reinforcing effects of the synthetic narcotic fentanyl is investigated. Methods: Rats with implanted catheters were allowed to self-administer fentanyl (2.0 μg/kg/infusion) on a fixed-ratio 1 of schedule of reinforcement. Results: A significant increase in lever pressing indicated the successful acquisition of fentanyl self-administration. Next, rats were presented with saline or various doses of MG. The cross-substitution of MG at three unit doses (0.3, 1.0, and 3.0 mg/kg/infusion) maintained the lever-pressing responses of the fentanyl self-administration while extinction was evident following the substitution of saline for the fentanyl solution. Conclusion: The differences in the profile of MG cross-substitution tests to the baseline level observed during extinction suggest that MG has fentanyl-like reinforcing effects. However, a more thorough examination of its primary reinforcing effects will need to be determined in naïve rats to confirm the potential dependence producing effects of MG.

Publisher

Faculty of Pharmaceutical Sciences, Chulalongkorn University

First Page

242

Last Page

247

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Pharmacology Commons

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