Therapeutic potential and liability of the Mitragyna speciosa (kratom) alkaloids
Abuse liability and therapeutic potential of the Mitragyna speciosa (kratom) alkaloids mitragynine and 7-hydroxymitragynine Abstract Kratom, derived from the plant Mitragyna speciosa, is receiving increased attention as an alternative to traditional opi- ates and as a replacement therapy for opiate dependence. Mitragynine (MG) and 7-hydroxymitragynine (7-HMG) are major psychoactive constituents of kratom. While MG and 7-HMG share behavioral and analgesic properties with mor- phine, their reinforcing effects have not been examined to date. 7-HMG, but not MG, substituted for morphine self- administration in a dose-dependent manner in the rat self-administration paradigm. Following the substitution proce- dure, re-assessment of morphine self-administration revealed a significant increase following 7-HMG and a significant decrease following MG substitution. In a separate cohort, 7-HMG, but not MG, engendered and maintained intrave- nous self-administration in a dose-depen...