Ellagic Acid Prevents Oxidative Stress and Memory Deficits in a Rat Model of Scopolamine-induced Alzheimer's Disease

Background: Ellagic acid (EA) has various pharmacological effects such as anti-inflammatory and anti-oxidant effects. Objective: This study aimed to investigate the effects EA on learning and memory dysfunction as well as oxidative stress in scopolamine-induced amnesic rats. Methods: The studied rats were treated according to the following protocol: Control (group 1) and scopolamine (group 2) groups received saline (intraperitoneal injection (i.p.)) while the treatment groups (group 3-5) were given EA (25, 50, and 100 mg/kg, i.p.) for 3 weeks. Thereafter, their behavioral performance was evaluated using Morris water maze (MWM) and passive avoidance (PA) tasks. Notably, scopolamine was injected (into groups II-V at a dose of 2 mg/kg, i.p.) before conducting the tasks. Finally, the oxidative stress indicators in the brain were measured. Results: EA reduced the escape latencies and distances during learning phase of MWM. The results of probe trials also indicated that EA improved memory retrieval and helped the animals recall the platform. Moreover, EA increased delay and light time, while decreasing the frequency of entries to the dark area of PA. In the EA-treated groups, the level of malondialdehyde was decreased, while the levels of total thiol groups, superoxide dismutase, and catalase were increased. Conclusion: EA prevented the negative effects of scopolamine on learning and memory which is probably mediated via modulating oxidative stress. Hence, EA could be considered as a potential alternative therapy in dementia.