Rosmarinic acid mitigates learning and memory disturbances in amyloid (25–35)-induced model of Alzheimer’s disease in rat

Background and Objective: Alzheimer’s disease (AD) is a weakening neurodegenerative disorder typified by increased ?-amyloid (A?) deposition and neuronal dysfunction causing to impaired learning and memory. Among proposed risk factors, induced oxidative stress is a main cause for incidence of the disease. The aim of this study was to determine the effects of the rosmarinic acid on learning and memory impairments with emphasis on its antioxidant properties. Materials and Methods: In the present study, the effect of the intraperitone-ally administration of rosmarinic acid (10 and 20 mg/kg) on learning and memory impairments was assessed in intrahippocampal A? (25–35)-injected rats. Results: The results showed that the intrahippocampal A? (25–35)-injected rats exhibit lower spontaneous alternation score inY-maze tasks (p < 0.005) and impaired retention and recall capability in the passive avoidance test (p < 0.05). Rosmarinic acid at both doses significantly improved alternation score in Y-maze task (p < 0.05-0.001) and restored retention and recall capability in the passive avoidance test only at a dose of 20 mg/kg (p < 0.005). Meanwhile, measurements of oxidative stress markers in hippocampal tissue of A?-injected rats showed significant elevation of malondialdehyde (MDA) and nitrite content (p < 0.05-p < 0.01) and rosmarinic acid significantly attenuated the increased MDA and nitrite content (p < 0.05) but did not affect SOD activity. Conclusion: This study indicates that rosmarinic acid pretreatment ameliorates A?-induced impairment of learning and memory in rats via attenuation of oxidative stress burden.