Effect of exercise and morphine on psychological and physical dependencies, BDNF and TrkB gene expression in rat’s hippocampus

OBJECTIVES: To compare the effect of exercise and morphine on abstinence syndrome and hippocampal gene expression in rat model. METHODS: Thirty adult male rats were exposed to voluntary wheel exercise (low, medium, high) for 28 days. The subjects entered Conditioned Place Preference (CPP) apparatus and experienced morphine (low, medium, high) CPP and followed by naloxone test. Correlation between exercise level, morphine injection, concurrent morphine administration and exercise with morphine CPP, BDNF and TrkB genes was determined. Rats were euthanized, decapitated and the hippocampus was removed. The expression of BDNF and TrkB genes were evaluated by real time PCR. RESULTS: Active rats ran an average of 839.18 m/d. A significant (P<0.001) correlation between exercise level, morphine injection, concurrent morphine administration and exercise with morphine CPP and BDNFand TrKB gene expressions was found. CONCLUSION: Voluntary exercise in different levels potentiates the brain rewarding system, CPP scale, and hippocampal BDNF and TrKB expressions. High range of voluntary exercise demonstrated an increase in the likelihood of developing addictive and drug-seeking behavior.