Chronic exposure to aluminum and melatonin through the diet: neurobehavioral effects in a transgenic mouse model of Alzheimer disease

Aluminum (Al) is a known neurotoxic element involved in the etiology of some serious neurodegenerative disorders such as Alzheimer disease (AD). Antioxidants like melatonin might protect neurons against the damage produced in AD. The APPSWE (Tg2576) transgenic mouse is one of the most used animal models developed to mimic AD damage. In the present study, wild type and Tg2576 mice were orally exposed during 14 months to Al, melatonin, and citric acid, as well as to all possible combinations between them. At 17 months of age, mice were evaluated for behavior using the open-field test and the Morris water maze. Transgenic animals exposed to melatonin only and to Al plus citric acid plus melatonin showed a good acquisition. No effects on acquisition in the Morris water maze were observed in wild type mice. With respect to the retention of the task, only melatonin wild type animals, and Al plus citric acid plus melatonin transgenic mice showed retention during the acquisition. Control wild type animals and Al plus citric acid plus melatonin transgenic mice showed good long term retention. Melatonin improved learning and spatial memory in Al-exposed transgenic mice.