Reasons
for Relapse
Inbred strains of rats differ in how aggressively they seek cocaine after a few weeks of use, researchers say.
The finding, posted online January 18 by Psychopharmacology, is another piece of evidence that genetics plays a role in the relapse of drug-seeking behavior in humans, said Dr. Paul J. Kruzich, MCG behavioral neuroscientist and lead study author.
It also cites the role of glutamate, a neurotransmitter involved in learning and memory, in stirring the cravings and uncontrollable urges that drive some drug users to use again.
“All persons addicted to psychostimulants can relapse, but potentially some are a little more susceptible than others; it’s all about gene-environment interaction,” said Dr. Kruzich.
He took two strains of inbred rats – Fischer 344 and Lewis – with known genetic differences, enabled each to self-adminster cocaine for 14 days, then removed the drug for a week but not the levers the animals used to access it. During that hiatus, he administered a drug that stimulates glutamate receptors, possible targets for drugs of abuse.
He found that the F344 strain worked harder to get cocaine than the Lewis rats following treatment with the glutamate drug, suggesting they were more susceptible to relapse.
“Maybe 12-step programs and faith-based programs will be enough to keep some people from relapsing,” said Dr. Kruzich. “For others, we may have to come up with medical treatments we can use on top of those to keep them from taking drugs again.”