Rats missing a neuroreceptor that controls the release of the neurotransmitter glutamate are less amenable to the rewarding effects of cocaine, increasing their chance of kicking the habit once addicted, researchers from the National Institute on Drug Abuse (NIDA) find. Their work, appearing July 11 in Cell Reports, suggests that the receptor, which protects nerve cells from fatal inundation by excess glutamate, is involved in modulating the reward-seeking behavior associated with drug addiction.
By silencing the gene responsible for expressing the receptor, called mGluR2, the researchers studied its effect across the stages of the cocaine addiction cycle. Rats without the receptor were more likely to consume cocaine when it was made freely available but less likely to seek out cocaine when they had to demonstrate more effort to obtain it. When cocaine was no longer available to them, the rats were quicker to cease the behaviors that had previously resulted in the drug’s delivery. Even when cocaine was subsequently re-introduced, they showed reduced interest for drug seeking, constituting a lower rate of relapse.