Effect of Temporal Exposure of Aluminum on Hippocampus Dependent Cognitive Functions and Post Exposure Recovery

Abstract

Due to higher load of development and industrialization animals and humans both are at higher exposure to metals especially Aluminum because of its high usage in everyday life. Higher level of aluminum in drinking water has long been linked with Alzheimer's and other cognitive dysfunctions. However, effect of time dependent exposure of aluminum on hippocampal dependent learning and memory has not been completely established. Mice model of temporal exposure of Aluminum (AlClз.6H2O) with same total exposure of 5850 mg/kg was used to elucidate whether Control group, 50 day exposure group (117 mg/kg/day), 20 day exposure group (292.5 mg/kg/day) or 35 day exposure group (175 mg/kg/day) produce reversible or irreversible damage to learning and memory. Behavioral tests used to determine the effect were Morris water maze, Y-maze test, Social interaction and novelty preference and Hole board test. The result of Morris water maze test showed that 50 day exposure group presented highest impairment than Control group in learning and memory with no significant recovery after recovery period. Y-maze result depicted highest learning and memory deficit in both, 50 day exposure group and 20 day group with almost irreversible damage. 35 day group exhibited least deficit in learning and memory and also presented significant recovery on their own after 20 days of with drawl of Aluminum exposure. Social interaction results were also consistent with previous results and presented 50 day exposure group with highest deficit in social novelty performance. 20 day exposure group showed slightly better performance than 50 day exposure group as 20 day exposure group showed slight recovery in 20 day recovery group. Hole board test for the analysis of reference and working memory presented highest impairment in 20 day exposure group and 50 day exposure group as compared to Control group with almost no recovery in their respective recovery groups. Whereas 35 day exposure group showed very little impairment in learning and memory and also better recovery in 35 day recovery group. It can be inferred from the results that both long term exposure with low dose and short term exposure with high dose both cause almost irreversible on its own hippocampal dependent learning and memory impairment. Future studies can reveal mechanism of temporal exposure of Aluminum suitable treatment depending on Aluminum daily exposure and duration.