Effects of fluoride and arsenic on spatial learning and memory function and it's mechanism in rats

ObjectiveTo explore the effects of fluoride,arsenic and their co-exposure on spatial learning and memory function and the oxidative damage in cerebral cortex in rats. MethodsThe Sprague-Dawley rats were randomly divided into four groups at the beginning of weaning.Three exposure groups were exposed to 120 mg/L sodium fluoride (NaF),70 mg/L sodium arsenite (NaAsO₂),and 120 mg/L NaF and 70 mg/L NaAsO₂ in drinking water for 90 days,respectively.The rats of control group drank distilled water for 90 days.The spatial learning and memory function were detected with Morris water maze.The levels of total antioxidant capacity (T-AOC),malondialdehyde (MDA),superoide dismutase (SOD),and glutathione peroxidase (GSH-Px) activity were measured using corresponding kits. ResultsThe escape latency periods of rats exposed to NaF,NaAsO₂,and the mixed solution were 10.34?1.18,11.76?1.23,and 13.78?3.49 s,respectively,and all of them were higher than that of the controls(5.85?1.98 s,all P<0.01).The first platform time of rats in the three exposure groups were all markedly higher than that of the controls (all P<0.05).The time in target quadrant and the times passing through the invisible platform within 120 s in the rats of the three exposure groups decreased significantly (all P<0.05).The levels of T-AOC and GSH-Px activity in cerebral cortex of NaF-exposed,NaAsO₂-exposed and co-exposed rats were 1.02?0.25,1.18?0.54,and 0.99?0.28 U/mL and 5.34?0.70,4.34?1.49,and 5.34?0.88 U/gprot,respectively,and all were much lower than those of controls (1.75?0.66 U/mL,6.82?0.85 U/gprot).Compared with control,NaF-exposed and co-exposed rats,the level of SOD in cerebral cortex of NaAsO₂-exposed rats was much lower (P<0.05).The level of MDA in cerebral cortex of NaF-exposed and co-exposed rats were markedly higher thant that of the controls (P<0.05). ConclusionFluoride,arsenic and their co-exposure at certain doses may damage spatial learning and memory function of rats.Oxidative damage in cerebral cortex may be related to the damaged spatial learning and memory function in rats.