Abstract

Despite decades of research, there are no medications approved by the United States Food and Drug Administration to treat stimulant use disorders. Self-administration procedures are widely used to screen candidate medications for stimulant use disorder, though preclinical reductions in stimulant self-administration have not translated to meaningful reductions in stimulant use in humans. One possible reason for this discordance is that most preclinical studies evaluate candidate medications under conditions that promote predictable, and well-regulated patterns of drug-taking rather than the dysregulated and/or compulsive patterns of drug-taking characteristic of a stimulant use disorder. A subset of rats ("high-responders") that self-administer 3,4-methelyendioxypyrovalerone (MDPV), a monoamine uptake inhibitor, develop high levels of dysregulated drug-taking consistent with behaviors related to stimulant use disorders. Because MDPV acts on dopamine, serotonin (5-HT), and sigma receptor systems, the current studies compared the potency and effectiveness of a dopamine D₃ receptor partial agonist (VK4-40) or antagonist (VK4-116), a sigma receptor antagonist (BD1063), a dopamine D₂/D₃/sigma receptor antagonist (haloperidol), and a 5-HT_2C receptor agonist (CP-809,101) to reduce MDPV (0.0032-0.1 mg/kg/infusion) self-administration in high- and low-responding rats as well as rats self-administering cocaine (0.032-1 mg/kg/infusion). VK4-40, VK4-116, haloperidol, and CP-809,101 were equipotent and effective at reducing drug-taking in all three groups of rats, including the high-responders, however, VK4-116 and CP-809,101 were less potent at reducing drug-taking in female compared to male rats. Together, these studies suggest that drugs targeting dopamine D₃ or 5-HT_2C receptors can effectively reduce dysregulated patterns of stimulant use, highlighting their potential utility for treating stimulant use disorders.

Significance Statement There are no FDA-approved treatments for stimulant use disorder, perhaps in part because candidate medications are most often evaluated in preclinical models using male subjects with well-regulated drug-taking. In an attempt to better model aberrant drug taking, this study found compounds acting at dopamine D₃ or 5-HT_2C receptors can attenuate drug-taking in male and female rats that self-administered two different stimulants and exhibited either a high- or low- substance use disorder-like phenotype.