Effects of environmental enrichment during induction of methamphetamine dependence on the behavioral withdrawal symptoms in rats.

This study was designed to examine the effect of environmental enrichment during METH administration on the behavioral withdrawal symptoms after drug abstinence in rats. Rats reared in standard (SE) or enriched environment (EE) during induction of METH dependence with bi-daily injections of METH (2mg/kg, at 12-h. intervals) for 14 days. Then, rats were evaluated for behavioral withdrawal symptoms, and also for anxiety (elevated plus maze-EPM) and depression (Forced swim test-FST) over a ten day period of abstinence. The results showed that stereotypic behaviors score and the number of rearing were significantly lower in METH/EE rats compared to the SE group during 1-4 days. Also, The METH/EE group exhibited more weight gain during 6-10 days of abstinence. The METH/EE rats exhibited lower levels of immobility after METH abstinence than control group in the FST. EE had no effect on anxiety-like behavior. This study showed that exposure to EE diminished the severity of withdrawal symptoms and depressive-like behavior during spontaneous withdrawal from METH.