Exercise Key in Fighting Addictions
People with addiction issues who exercise appear to be less vulnerable to the impact of environmental cues that prolong drug addiction, according to research in the journal ACS Omega.
Prior studies have shown that exercise can reduce craving and relapse in addicts, as well as mice.
Although the mechanism was unknown, exercise was thought to alter the learned association between drug-related cues and the rewarding sensations of taking a drug, possibly by changing the levels of peptides in the brain.
Jonathan Sweedler, Justin Rhodes and colleagues at the University of Illinois at Urbana-Champaign decided to explore this theory by quantifying these peptide changes in mice.
Mice were given cocaine injections over four days in special chambers with a distinctive floor texture to produce a drug association with that environment.
The animals were then housed for 30 days in cages, some of which included a running wheel.
The researchers found that mice that exercised on these wheels had lower levels of brain peptides related to myelin, a substance that is thought to help fix memories in place.
Re-exposure to the cocaine-associated environment affected running and sedentary mice differently: Compared with sedentary mice, the animals with running wheels showed a reduced preference for the cocaine-associated environment.
In addition, the brains of re-exposed runners contained higher levels of haemoglobin-derived peptides, some of which are involved in cell signalling in the brain.
Meanwhile, peptides derived from actin decreased in the brains of re-exposed sedentary mice.
Actin is involved in learning and memory and is implicated in drug seeking. The researchers say these findings related to peptide changes will help to identify biomarkers for drug dependence and relapse.
Read more: Environment Key in Quitting Addictions