Increasing the selectivity of drug discrimination procedures

Area of Science:

• Neuroscience
• Pharmacology
• Behavioral Science

Background:

• Drug discrimination studies are crucial for understanding drug effects and developing new therapeutics.
• Traditional methods using saline as a control may not adequately differentiate between drugs with similar psychoactive properties.

Purpose of the Study:

• To investigate if training rats to discriminate lysergic acid diethylamide (LSD) from a diverse group of other drugs enhances discrimination selectivity compared to the standard saline control.
• To assess the generalizability of this enhanced discrimination with various psychoactive compounds.

Main Methods:

• Rats were trained to discriminate LSD from either a mixture of cocaine, pentobarbital, and saline, or from saline alone.
• Substitution tests were conducted using various hallucinogens, designer drugs, and known "false positive" compounds to evaluate generalization patterns.

Main Results:

• The LSD-other discrimination task was acquired rapidly and showed similar acquisition times to the LSD-saline task.
• Hallucinogens like DMT and DOM generalized to LSD in both training paradigms.
• (+/-)MDMA substituted for LSD in the LSD-other group but not the LSD-saline group.
• Crucially, known "false positive" drugs (lisuride, quipazine, yohimbine) substituted for LSD in the LSD-saline group but not in the more selective LSD-other group.

Conclusions:

• Training rats to discriminate LSD from a mixture of other drugs significantly increases the selectivity of the drug discrimination procedure.
• This refined methodology offers a more precise tool for characterizing the discriminative stimulus properties of drugs, particularly in differentiating psychoactive effects and identifying potential false positives.