Reinforcing Potency and Effectiveness of Synthetic Cathinones: Potency versus Selectivity for DAT

Synthetic cathinones found in “bath salts” preparations interact with monoamine transporters and function as either cocaine‐like monoamine uptake inhibitors or amphetamine‐like substrates. Abuse of these synthetic cathinones has resulted in regulation of some cathinones internationally. Modifications to the chemical structure of regulated cathinones (e.g., MDPV) produce a series of new cathinones (e.g., α‐PVP, α‐PPP, MDPBP, and MDPPP) which may not be subject to existing regulations. Although MDPV is a more potent and effective reinforcer than cocaine, little is known about the reinforcing effects of other synthetic cathinones. Thus, this study examined intravenous self‐administration of cocaine, MDPV, α‐PVP, α‐PPP, MDPBP, and MDPPP to test the hypotheses that 1) stimulants with greater potency to inhibit the dopamine transporter (DAT) are more potent reinforcers, and 2) stimulants with greater selectivity for DAT relative to the serotonin transporter (SERT) are more effective reinforcers. Potencies to inhibit monoamine uptake at DAT and SERT were determined using synaptosomes prepared from rat brains. Separate groups of male Sprague‐Dawley rats (n=12 per group) were used to generate full dose‐response curves under a progressive ratio (PR) schedule of reinforcement for α‐PVP, α‐PPP, MDPBP, and MDPPP; full dose‐response curves for MDPV and cocaine were also generated in each rat (n=48). Rank order potency to inhibit DAT was MDPV > α‐PVP ≈ MDPBP > MDPPP ≈ α‐PPP ≈ cocaine, while rank order DAT/SERT selectivity was α‐PVP > α‐PPP > MDPV > MDPBP > MDPPP > cocaine. The potency to inhibit DAT correlated with the potency of each drug to maintain responding (MDPV > α‐PVP ≈ MDPBP > MDPPP ≈ α‐PPP ≈ cocaine). Relative reinforcing effectiveness as determined by comparing the maximum number of infusions obtained for each drug under a PR schedule of reinforcement was α‐PVP > α‐PPP ≈ MDPV > MDPBP ≈ MDPPP > cocaine, which correlated with DAT/SERT selectivity. These data suggest that (1) potency at DAT is an important determinant of the potency of each drug to function as a reinforcer, (2) each of these synthetic cathinones functions as a more effective reinforcer than cocaine, and (3) DAT/SERT selectivity is related to reinforcing effectiveness and may predict the abuse‐related effects of novel synthetic cathinones in humans. Support or Funding Information These experiments were supported by NIH grants R01DA039146 (GTC) and T32DA031115 (BMG) and the Intramural Research Programs of NIDA (MHB, KCR) and NIAAA (KCR). This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .