Long-term morphine addiction reduces neurogenesis and memory performance and alters emotional reactivity and anxiety levels in male rats

Abstract

Introduction: Substance abuse is a behavioral disorder associated with a wide variety of devastating effects. Neurogenesis in dentate gyrus of hippocampus is essential for brain functions like memory formation. Therefore, this may play an important role in achieving successful withdrawal. Methods and materials: Twenty Sprague-Dawley rats were randomly divided into two experimental groups: control and addiction. To induce morphine dependence, animals received morphine (0.75 mg/rat) for 21 days. The performance of animals in Morris water maze and elevated plus maze tests was evaluated after day 20. At the end of the study, the rats were decapitated, and their brains were sectioned to study neurogenesis by counting BrdU-positive cells. Results: Hippocampal neurogenesis was significantly reduced in rats in the addicted group. Also, reference and working memory performance were impaired in animals in the addicted group. A decrease in emotional reactivity and anxiety was observed in animals in the addicted group when compared with that in the control group. Conclusion: Addiction adversely affects brain functions and neurogenesis; thus treatment to increase neurogenesis is the better option for the persons with substance abuse.