Acute behavioral effects of co-administration of mephedrone and MDMA in mice

Background: Abuse of more than one psychoactive drug is becoming a global problem. Our experiments were designed to examine the effects of a concomitant administration of 3,4-methylenedioxy-methamphetamine (MDMA) and mephedrone on depression-and anxiety-like behaviors and cognitive processes in Swiss mice. Methods: In order to investigate the drug interactions the forced swimming test (FST) - an animal model of depression, the passive avoidance (PA) test - a memory and learning paradigm, as well as the elevated plus maze (EPM) test - test for anxiety level were used. Results: The results revealed that a concomitant administration of non-effective doses of mephedrone (1 mg/kg) and MDMA (1 mg/kg) exerted marked antidepressive effects in the FST. Also a co-administration of mephedrone (2.5 mg/kg) and MDMA (1 mg/kg) displayed a pro-cognitive action in the PA paradigm. Furthermore, even though mephedrone and MDMA can, in general, exert some anxiogenic effects in mice, the concomitant administration of nonactive doses of both drugs (0.05 and 0.1 mg/kg, respectively) in the EPM test, did not show any synergistic effect in our study. Conclusions: The effects of mephedrone and MDMA combination on mammalian organisms were attempted to be evaluated in our study and the results are described in the present report. These results may help explain the reasons for and consequences of a concomitant administration of psychoactive substances with regards to the central nervous system, while being possibly useful in the treatment of polydrug intoxication. (C) 2016 Published by Elsevier Sp. z o.o. on behalf of Institute of Pharmacology, Polish Academy of Sciences.