Abuse‐Related Discriminative Stimulus Effects of Synthetic Cathinones

Abstract

The use of synthetic cathinones, or “bath salts,” has become more widespread in recent years. “Bath salts” share many chemical properties with psychostimulants like methamphetamine or with entactogens like 3,4‐methylenedioxymethamphetamine (MDMA or “Ecstasy”), presumably reflecting structural differences that lead to differing neurochemical actions. Yet, currently available synthetic cathinones have not been well‐characterized in primate species, and it is unclear which pharmacological activity mediates their abuse‐related behavioral effects. The present study was initiated to address this question, using drug discrimination procedures to evaluate several synthetic cathinones in two groups of squirrel monkeys. Each subject was trained to respond on either of two levers under a FR10 schedule of reinforcement and, during training sessions, responding on one lever was reinforced after pretreatment with vehicle whereas responding on the second lever was reinforced after pretreatment with the training drug. Under terminal conditions, one group of monkeys discriminated 0.1 mg/kg methamphetamine from saline; the other group discriminated 0.6 mg/kg MDMA from saline. Drug or saline lever assignments were counter balanced across the left and right levers within each group. Training sessions comprised multiple components, and a component consisted of a ten‐minute timeout period followed by ten presentations of the FR10 schedule, each followed by a brief 50‐second timeout. After criterion performance was met (≥ 90% correct), test days interspersed training days, with at least two training days between each test day. The effects of five different synthetic cathinones ‐ α‐pyrrolidinovalerophenone (α‐PVP), methylenedioxypyrovalerone (MDPV), mephedrone, methylone, and methcathinone) were tested in both groups. A full range of doses of each drug was administered using cumulative dosing procedures. Results show that doses of 0.1 mg/kg – 0.32 mg/kg of MDPV, α‐PVP, and methcathinone were identified as methamphetamine in subjects trained to discriminate 0.1 mg/kg methamphetamine from vehicle, whereas doses mephedrone and methylone up to those that decreased overall response rates did not generalize to MA. Preliminary results suggest an opposite profile of substitution in MDMA‐trained animals. Thus, mephedrone and methylone, but not MDPV, α‐PVP, and methcathinone did appear to generalize to MDMA. These results demonstrate that synthetic cathinones have differing substitution profiles in animals trained to discriminate methamphetamine or MDMA, which may reflect differing subjective effects and, perhaps, differing abuse liability in man.Support or Funding InformationSupported by NIH Grants: DA002519. GM113117, DA039306, GM111385This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.