Temporal factors in drug discrimination: Experiments with nicotine

Area of Science:

• Neuroscience
• Pharmacology
• Behavioral Science

Background:

• Drug discrimination research uses operant conditioning to study drug effects.
• The presession interval (PI) is a temporal parameter that may influence drug cue properties.
• Nicotine discrimination in rats is a common model for studying nicotinic acetylcholine receptor ligands.

Purpose of the Study:

• To investigate the role of the presession interval (PI) in nicotine drug discrimination.
• To determine if different PIs during training lead to qualitative or quantitative differences in nicotine cues.
• To assess the impact of PI on cue sensitivity to a nicotinic antagonist and generalization to another drug.

Main Methods:

• Rats were trained to discriminate nicotine from saline using a two-bar operant conditioning procedure.
• Different groups were trained with varying PIs (5-35 min).
• Tests included generalization to amphetamine and antagonism by mecamylamine.

Main Results:

• Complete generalization of nicotine cues across different PIs was observed.
• Nicotine cue sensitivity to mecamylamine was similar across PIs.
• Generalization to amphetamine varied, being more complete with longer PIs (20-35 min).
• Increasing PI during training decreased ED(50) (increased sensitivity), while increasing PI during testing increased ED(50) (decreased sensitivity).

Conclusions:

• No clear qualitative differences were found for nicotine cues trained with different PIs.
• The PI significantly and complexly influences quantitative aspects of the nicotine cue.
• Pharmacokinetic factors likely explain the observed changes in ED(50) values.
• Temporal parameters like PI are critical for the sensitivity of drug discrimination procedures.