Self-injection of amphetamine directly into the brain

Area of Science:

• Neuroscience
• Behavioral Pharmacology
• Addiction Research

Background:

• The nucleus accumbens is implicated in reward processing.
• Understanding the neural basis of drug reinforcement is crucial for addiction research.

Purpose of the Study:

• To investigate if d-amphetamine acts as a positive reinforcer when self-administered directly into the nucleus accumbens in rats.
• To determine the specific brain region responsible for amphetamine's rewarding effects.

Main Methods:

• Rats were trained to self-administer d-amphetamine via cannulation of the nucleus accumbens.
• Response rates and lever choices were recorded under different conditions.
• Drug delivery was tested through accumbens versus ventricular cannulation.

Main Results:

• Rats reliably self-administered d-amphetamine, showing higher responding for the drug than saline.
• Animals regulated their intake, reducing self-administration when receiving automatic infusions.
• Response extinction occurred when drug delivery was switched from the nucleus accumbens to ventricles.

Conclusions:

• Direct nucleus accumbens self-administration of d-amphetamine functions as a positive reinforcer.
• This finding localizes a key neural mechanism for amphetamine reward within the nucleus accumbens.
• The nucleus accumbens may play a significant role in both drug abuse and natural reinforcement behaviors.