Methoxetamine, a ketamine derivative, produced conditioned place preference and was self-administered by rats: Evidence of its abuse potential.
Chrislean Jun Botanas, J. B. de la Peña, I. J. D. Dela Peña, Reinholdgher Tampus, Robin Yoon, H. Kim, Yong Sup Lee, C. Jang, J. Cheong
Pharmacology, Biochemistry and Behavior June 1, 2015 DOI: 10.1016/j.pbb.2015.03.007 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Experimental study Peer reviewed |
|---|---|
| Population | Sprague-Dawley rats |
| Interventions | Methoxetamine Ketamine |
| Dose | MXE: 2.5 and 5 mg/kg (CPP), 0.25, 0.5, 1.0 mg/kg/infusion (SA); Ketamine: 5 mg/kg (CPP), 0.5 mg/kg/infusion (SA) |
| Topics | Esketamine Ketamine |
| Key findings | MXE produced significant conditioned place preference at 2.5 and 5 mg/kg, comparable to ketamine at 5 mg/kg, and modest self-administration at 0.25, 0.5, and 1.0 mg/kg/infusion, while ketamine at 0.5 mg/kg/infusion was robustly self-administered. MXE did not alter locomotor activity, whereas ketamine decreased it. The authors suggest MXE has abuse potential and warrants regulation. |
Abstract
Methoxetamine (MXE) is an N-methyl-d-aspartate (NMDA) receptor antagonist that is chemically and pharmacologically similar to ketamine. Recently, there have been many reports regarding its use/misuse in humans which have resulted in serious or even fatal outcomes. Despite these reports, MXE is not controlled or regulated in many countries which may be partly due to the lack of scientific evidence regarding its abuse potential. Thus, in the present study we evaluated the abuse potential (rewarding and reinforcing effects) of MXE through the conditioned place preference (CPP) and self-administration (SA) tests in Sprague-Dawley rats. In addition, locomotor activity during the conditioning phase of the CPP was also analyzed. Ketamine was used as a reference drug. MXE (2.5 and 5mg/kg) induced significant CPP in rats, an effect comparable to that of ketamine (5mg/kg). Interestingly, MXE did not produce any locomotor alterations while ketamine decreased the locomotor activity of rats. In the SA test, rats showed modest self-administration of MXE (0.25, 0.5, 1.0mg/kg/infusion), while ketamine (0.5mg/kg/infusion) was robustly self-administered. These results demonstrate that MXE, similar to ketamine, has rewarding and reinforcing effects in rats. The present study strongly suggests that MXE has a potential for human abuse. In addition, the discrepant effects of MXE and ketamine on locomotor activity and rate of self-administration propose that the psychopharmacological effects of these drugs may diverge in some aspects. More importantly, this study advocates the careful monitoring and prompt regulation of MXE and its related substances.