Abstract
Introduction: Withdrawal period from abused substance is accompanied by many problems. In some addicted people, relapse to drug-seeking and compulsive abuse develops. On time intervention may reduce relapse in some addicted people by knowing underlying mechanism.
Methods and Materials: In this study 48 rats were randomly divided into four groups: pair, isolation, withdrawal pair, and withdrawal isolated. Rats in withdrawal groups after one week for acclimatization were first induced for morphine addiction by injection of increasing dose of morphine (5 mg/kg/rat in the first day to the final dose of 35 mg/kg/rat) for 7 days and then were withdrawn from morphine by the injection of naltrexone (3 mg/kg/rat) in 8 days. In control groups no treatment was applied. On day 14, rats in all groups were first evaluated for avoidance memory and novelty-seeking behavior. Then rats in day 15 were sacrificed and brain immediately removed for the assessment of oxidative stress (OS) status in the hippocampus and prefrontal cortex for malondialdehyde (MDA), glutathione and nitrite/nitrate.
Results: Avoidance memory was better in withdrawal pair rats. Novelty-seeking behavior was increased in withdrawal isolated rats. Anxiety was reduced in withdrawal isolated rats. MDA was higher in withdrawal isolated rats. Glutathione and nitrite/nitrate were higher in withdrawal isolated rats.
Conclusion: Pair state (socialization) improves avoidance memory, increases anxiety and reduces novelty-seeking behavior in withdrawal period. Also, oxidative stress markers responded differently to withdrawal stress in isolated and pair rats.
Keywords: Avoidance memory and anxiety, glutathione, MDA, nitrite/nitrate, novelty-seeking behavior, prefrontal, hippocampus.
Graphical Abstract
26