Neuropathological Changes in Hippocampus in Albino Rat in Fluoride Toxicity

The study was carried out to evaluate the neuropathological effect of sodium fluoride in hippocampus of albino rat. Healthy albino rats of Wistar strain weighing 100-200 g were divided in four groups. Group I was given 1 ml double distilled deionized water/kg body weight/day for forty days and kept as control. The remaining groups II, III and IV were treated with 100, 200 and 300 ppm of sodium fluoride/kg body weight/day via oral gavage for the same period. The rats were sacrificed and hematoxylin and eosin stained sections of hippocampus were studied for neuropathological abnormalities. In rats treated with 100 ppm sodium fluoride, the hippocampus showed various degree of disarrangement of pyramidal layer. The pyramidal neurons appeared distorted with elongated rod shaped nucleus. Shrunken and darkly stained nuclei were visible in some neurons as compared to control. In rats treated with 200 ppm sodium fluoride, many neurons displayed irregularities in their structure and distribution. A decrease in the density of pyramidal cells in CA1 region was observed. The neuropil displayed various degree of necrosis, granular cells showed vacuolation and disintegration of neuroplasm. In hippocampus of rats treated with 300 ppm sodium fluoride, neurotoxic changes were very much prominent compared to control. Constricted blood capillaries were visible in the neuropil. Some nerve cells contained pyknosed nuclei. The polymorphic layer depicted degeneration and atrophied nerve cells. At some locations, clear halos were visible in neuropil. Some granule cells and pyramidal neurons exhibited chromatolysis. The findings of present study illustrated that fluoride may worsen the cytoarchitectural arrangement in the hippocampus by altering the structure of pyramidal neurons and neuroglia. The nuclei of pyramidal neurons in hippocampus may be the main organelle that gets affected and starts depicting variation in size and structure in different concentration of sodium fluoride.