Mephedrone ("bath salt") pharmacology: insights from invertebrates

Psychoactive bath salts (also called meph, drone, meow meow, m-CAT, bounce, bubbles, mad cow, etc.) contain a substance called mephedrone (4-methylcathinone) that may share psychostimulant properties with amphetamine and cocaine. However, there are only limited studies of the neuropharmacological profile of mephedrone. The present study used an established invertebrate (planarian) assay to test the hypothesis that acute and repeated mephedrone exposure produces psychostimulant-like behavioral effects. Acute mephedrone administration (50-1000 μM) produced stereotyped movements that were attenuated by a dopamine receptor antagonist (SCH 23390) (0.3 μM). Spontaneous discontinuation of mephedrone exposure (1, 10 μM) (60 min) resulted in an abstinence-induced withdrawal response (i.e. reduced motility). In place conditioning experiments, planarians in which mephedrone (100, 500 μM) was paired with the non-preferred environment during conditioning displayed a shift in preference upon subsequent testing. These results suggest that mephedrone produces three behavioral effects associated with psychostimulant drugs, namely dopamine-sensitive stereotyped movements, abstinence-induced withdrawal, and environmental place conditioning.