Blocking dopamine receptors reduces the effects of cocaine use

Blocking dopamine receptors in various regions of the brain’s amygdala reduces the activities associated with seeking and using drugs, according to a study by researchers at Oregon Health & Science University (OHSU) in the US and published in the journal, eNeuro.

The amygdala is a region in the medial temporal lobe of the brain. It plays a vital role in processing emotions and contains a set of dopamine receptors, which are neurotransmitters concerned with reward-seeking behaviours. Previous studies have shown that it influences reward behaviours associated with cocaine use, making it an ideal focus for research on addiction treatment.

Researchers Earnest Kim and Matthew Lattal at OHSU blocked the receptors of dopamine in the amygdala of rats that were self-dispensing doses of cocaine. The researchers trained the rats to press on a lever that deployed a second lever; the behaviour modelled seeking a source of drugs. The researchers also trained the rats to press on the second lever, which released a dose of cocaine; this behaviour modelled taking drugs.

The researchers evaluated the effects of blocking dopamine receptors in two sections of the amygdala. When they blocked the receptors in the basolateral amygdala, the rats decreased their drug-seeking and drug-taking behaviours and continued to do so even when placed in a new testing environment. Blocking the dopamine receptors in the central amygdala resulted in a quick decrease in looking for and taking cocaine, but the effect was reversed when the researchers moved the rats to a new testing area. The research shows the different roles of the two sections of the amygdala and provides insights on how to proceed with the possible treatment of drug addiction and relapse.