The Impact of Crocin and Chronic Isolation Stress on Passive Avoidance Memory and Brain Electrical Activity in Male Rats

Abstract

Introduction: Crocin and stress affect different aspects of brain functions. Chronic isolation stress is prevalent in today's world. Therefore, this study investigated the impact of crocin and chronic isolation stress on learning, memory, and different brain waves in male rats.Methods: Forty male Wistar rats were allocated to five groups: control, sham, chronic isolation stress (CIS), two stress groups receiving different doses of crocin (CIS-Cr30 and CIS-Cr60). Both chronic isolation stress (6h/day) and crocin administration were induced for 21 days. The passive avoidance test evaluated initial and step-through latencies (IL and STL, respectively), as well as total dark compartment, and stay time. Also, different brain waves were measured by EEG recording. Results: The STL declined in the CIS and CIS-Cr30 groups while it significantly increased in only the CIS-Cr60 group. Also, the total dark compartment stay time increased in the CIS group, whereas it decreased by crocin (30 and 60 mg/kg) in the CIS group. The percentages of beta and alpha waves decreased whereas theta waves significantly increased in the CIS group. While the percentage of the beta and alpha waves increased as well as the percentage of the theta and delta waves decreased by crocin at a dose of 60 mg/kg in the CIS group.Conclusion: Cronic isolation stress was so destructive and it impaired learning, memory as well as alpha, beta, and theta waves in the brain. Only a dose of 60 mg/Kg of crocin reversed memory deficit and affected all brain waves in subjects under chronic isolation stress. Therefore, the doses of 60 and 30 mg/kg of crocin had different effects on electrophysiological and behavioral brain functions under chronic isolation conditions.