Effect of Rheum Ribes Hydro-Alcoholic Extract on Memory Impairments in Rat Model of Alzheimer's Disease.

Some animal models have been used to study Alzheimer's disease (AD). AD is an irreversible progressive neurodegenerative disease and the most common cause of dementia. Animal studies have shown that there is a relation between decrease in cholinergic functions in the nucleus basalis of Meynert (NBM) and loss of learning capability and memory. The aim of this study was to investigate the effect of Rheum ribes extract (RR) on memory deficit in one of the rat models of AD. Plant (1500gr) was collected from Saman (kahkesh) region of Chaharmahal Va Bakhtiari province in Iran. RR hydro-alcoholic extracts were prepared using maceration method. Rat model of Alzheimer was induced by Nucleus Basalis of Meynert lesions (NBML). Animals (n = 32) received extracts for 20 days and then passive avoidance and Morris water maze tasks were performed for memory evaluation. FRAP and HPLC methods were used for measurement of the antioxidant and Malondialdehyde (MDA) levels in blood. In water maze experiment, probe trial results showed that NBML group spent significantly less time in target quadrant, in which the platform was located on the preceding day. In addition, the time spent in target quadrant was significantly increased in NBML + RR groups (250 and 500 mg/kg) compared to the NBML group. In passive avoidance task, mean initial latency time and step-though latency were significantly decreased in NBML group. RR extracts significantly prolonged step-through latency in NBML + RR groups. Results of this study suggest that Rheum ribes extracts can improve memory deficits induced by bilateral NBM lesions in rats.