Fluoride Action Network


The effect of exposure to different concentrations of sodium fluoride (Na-F) for different durations on learning and memory tasks in rats (non-associative and associative learning) was assessed in our study. Three groups of fifteen pregnant Wistar female rats each, were administered Na-F in drinking water at one of three concentrations; 0, 50 and 100 ppm from second trimester of pregnancy till weaning of their pups at 30 days of age. Pups were then allocated into 5 groups of 20 animals each, where Na-F was administered in three different concentrations with different exposure periods throughout the study. Brain tissue specimens, representing all treatment groups, were taken for histopathological examination. The average body weight gain was significantly lower in group of rats exposed to high Na-F doses for long duration, with distinct hair loss. Open field revealed a significant influence of dose of Na-F on exploratory motor activities (EMA) and emotionality with marked impairment in habituation in rats exposed to high Na-F. Moreover, learning and memory assessed during maze test showed reduced memory retention in rats exposed to high Na-F for long periods. In novelty acquisition test, despite evidence of occurrence of habituation in all groups, a noticeable reduced degree was demonstrated in rats continued to administer high Na-F for long duration. Furthermore, histopathological evaluation revealed distinct neurodegenerative changes of nerve cells especially in hippocampus. Our results suggest that exposure of rats to Na-F in high doses for long duration has detrimental effects on the brain as reflected in diminished learning and memory.