Extra (non-contingent) food does not affect behavioral tolerance to d-amphetamine's rate-decreasing effects

Area of Science:

• Neuroscience
• Pharmacology
• Behavioral Science

Background:

• Drug tolerance is a reduced response to a drug after repeated use, necessitating higher doses for the same effect.
• Tolerance to drugs affecting operant behavior is linked to initial reinforcement loss.
• The impact of mitigating reinforcement loss on tolerance development remains unclear.

Purpose of the Study:

• To investigate if offsetting reinforcement loss influences the development of tolerance to d-amphetamine.
• To determine if providing non-contingent food pellets affects tolerance to d-amphetamine's impact on operant behavior in rats.

Main Methods:

• Rats were trained to press a lever for food pellets under a multiple schedule.
• Extra food pellets were administered non-contingently (variable-time schedules) in one component.
• The effects of d-amphetamine were assessed acutely and chronically (45 days) to quantify tolerance development.

Main Results:

• d-amphetamine produced a dose-dependent decrease in lever pressing and food pellet acquisition.
• Tolerance to d-amphetamine developed similarly in conditions with and without extra food pellets.
• Offsetting reinforcement loss did not differentially affect the development of tolerance.

Conclusions:

• Mitigating reinforcement loss, through non-contingent food delivery, did not significantly alter tolerance development to d-amphetamine.
• These findings suggest that the relationship between reinforcement loss and drug tolerance may be more complex than previously assumed.
• Further research is needed to explore other factors that might influence drug tolerance in operant behavior paradigms.