The subjective effects of drugs, such as euphoria or dysphoria, can be studied using the drug discrimination procedure. Over the past two decades, abuse of hallucinogenic club drugs like PCP, MDMA, LSD, and ketamine has increased, especially among younger people, but the mechanisms behind their discriminative stimulus effects remain unclear. This review of recent animal research identifies at least two plausible mechanisms: one mediated mainly by 5-HT2 receptors, and another mediated through sigma-1 (σ1)-receptor chaperone regulated by an endogenous hallucinogenic ligand.
Drug discrimination procedures help researchers understand the subjective effects of drugs, such as euphoria or dysphoria. Over the past two decades, abuse of club and recreational drugs like PCP, MDMA, ketamine, and cannabinoids has increased, particularly among younger people. Designer drugs that mimic psychostimulants like MDMA or amphetamines are also problematic. However, the mechanisms behind the discriminative stimulus effects of hallucinogenic and dissociative anesthetic drugs remain unclear. This chapter reviews recent animal research on these drug-induced discriminative stimulus properties.