Protective effect of Morinda citrifolia fruits on beta-amyloid (25-35) induced cognitive dysfunction in mice: an...

The neuroprotective effect of an ethyl acetate extract of Morinda citrifolia (Rubiaceae) Linn. fruits (EMC, ethyl acetate extract of Morinda citrifolia) at doses of 200 and 400 mg/kg, p.o. was studied on beta-amyloid (25-35) peptide induced cognitive dysfunction in mice. In the step-down inhibitory avoidance, EMC exhibited a significant increase in short-term memory and long-term memory (p < 0.05). A significant decrease (p < 0.01) in escape latency was noticed in the animals in the water maze. A significant increase (p < 0.01) in alteration of behavior was exhibited upon administration of EMC 200 and 400 mg/kg on the Y maze. Exploratory parameters such as line crossings, head dipping and rearing were increased significantly in EMC treated groups in a dose-dependent manner (p < 0.05 and p < 0.01). A significant reduction (p < 0.05) in acetyl cholinesterase activity was noticed in the EMC 200 and 400 mg/kg treated groups. The level of monoamine oxidase-A was decreased by the administration of EMC 200 and 400 mg/kg (p < 0.05 and p < 0.01, respectively). EMC at a dose of 400 mg/kg exhibited a significant increase (p < 0.01) in the levels of serotonin and dopamine. Antioxidant enzymes such as superoxide dismutase, glutathione reductase, glutathione peroxidase and ascorbic acid were decreased significantly in the b-amyloid peptide injected group, whose levels were restored significantly (p < 0.01) by the administration of EMC (400 mg/kg).