Effect of Time Dependent Exposure of Cadmium on Hippocampus Dependent Cognitive Functions and Their Post Exposure Recovery in Mice

Abstract

The Cadmium (Cd) has been identified as the most toxic industrial and environmental pollutant. It disturbs the functioning of several organs (kidneys, lungs) and tissues following either acute or chronic exposure. Cd has a long half-life in the human body (about 10–30 years) so it can induce cell death in different neuronal cells and primary neural stem/progenitor cells. This study was aimed to investigate the toxic effect of Cd on cognitive function in mice. Three groups of 6-8 weeks-old BALB/c male mice was exposed to 900mg/Kg Cd (in the form of CdCl2) through drinking water for 20, 35 and 50 days respectively. The behavior tests were conducted after 15, 30 and 45 days respectively. After the exposure, the recovery of same animals was also checked after 20 days period through same behavior tests. The results of Morris water maze test showed highest impairment in learning and memory in 50 day group and this group also showed least recovery after recovery period. Y-maze results showed highest impairment in 20 day and 50 day group. The 50 day group showed a little recovery but the 20 day group had irreversible damage. While the 35 day group have less impairment and also recover on its own. Social interaction results were also similar with the previous results, as the 50 day group showed highest deficit in novelty preference with no significant recovery. 20 day group also showed impairment but there was some recovery observed in novelty preference. Hole board test to check the working and reference memory error showed highest impairment in 50 day group and then 20 day group as compared to control. While 35 day group show less impairment and better recovery. 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 impairment on hippocampal dependent learning and memory. Future studies can reveal mechanism of temporal exposure of Cadmium suitable treatment depending on Cadmium daily exposure and duration