In the study, the researchers found that exposing mice to an "enriched environment" during cocaine withdrawal removes abnormal behavior related to addiction.
An enriched environment, for mice, is an environment, which stimulates their curiosity, providing social and physical activity as well as exploration.
After addicting animals to cocaine, the researchers then exposed them to an enriched environment made up of large cages with a small house, a running wheel, tunnels and other appealing toys, which were changed weekly.
Three models of animal addiction were used - behavioral sensitization, which measures the progressive increase in the stimulating effects of cocaine after chronic administration; the location preference, which measures the ability of a context ie associated with cocaine consumption to lead to drug-seeking behavior, and the renewal of this drug-induced location preference; measurements of cocaine's ability to lead to a relapse after a period of withdrawal.
The researchers found that after thirty days of exposure to an enriched environment, addiction behavior typical of these three models had disappeared.
To identify the brain areas involved in the beneficial effect of an enriched environment, the researchers used an approach from functional neuro-anatomy.
They showed that the absence of relapse in "enriched" mice was associated with a decrease in the cocaine-induced activation of a set of brain structures involved in dopaminergic transmission and associated with relapse.
These findings suggest that the living conditions of drug addicts should be considered in determining their therapy.