Betaine attenuates oxidative stress and cognitive dysfunction in an amyloid β-induced rat model of Alzheimer’s disease

Increasing evidence indicates that oxidative stress is an important factor in the pathogenesis and progression of Alzheimer's disease (AD). Betaine is trimethylglycine with antioxidant and neuroprotective properties. The present study aimed to evaluate the possible beneficial effects of betaine on oxidative stress and memory deficits induced by intrahippocampal injection of amyloid beta (Aß) in an AD model.Forty adult male Wistar rats were divided into 5 equal groups: the control and Aß groups which received oral gavage of saline (1 mL daily) for 14 days. The other 3 groups (betaine + Aß) received betaine (5, 10, and 15 mg/kg, orally) for 14 consecutive days. On the 15th day, all of the groups were injected bilaterallyintrahippocampal of Aß (5 µg/µL), except controls that were injected with normal saline as a vehicle. Seven days after the Aß injection, memory was assessed in a passive avoidance test. Changes in catalase activities and glutathione peroxidase, glutathione, and malondialdehyde concentrations were investigated to determine the antioxidant activity in the rat hippocampus.Data showed that betaine pretreatment of Aß-injected rats improved memory in avoidance tasks. In addition, betaine pretreatment attenuated oxidative stress.The current findings showed that oral administration of betaine could prevent Aß-induced impairment of memory possibly through suppression of oxidative stress in the hippocampus area of rats.