Fluorosis, as a consequence of exposure to high amount of fluoride is a serious public health problem in many parts of world. Fluoride can cause severe damage to the dental and skeletal systems, and is known to be an endogenous neurotoxin. In the present study, Wister albino rats of weighing 100-200 g were given 100, 200 and 300 ppm of sodium fluoride per kg body weight per day for forty conjunctive days while control were given 1 ml double distilled deionized water per kg body weight per day for same duration. The rats were sacrificed under ether anesthesia after fluoride treatment and cerebrum was carefully removed and fixed in Bouin’s fluid for neuropathological examination. Neuropathological examinations of cerebrum in fluoride treated rat revealed that some pyramidal neurons showed chromatolysis and were shrunken with vacuolation around them. The nuclei of many pyramidal neurons were eccentric in neuroplasm, irregular and spindle shaped, others were exhibiting necrosis and some presented dark constricted dot like structure. In few pyramidal neurons, the nuclei appeared as eosinophilic or red. Some pyramidal neurons in certain region showed hyperchromatic and hypertrophic nucleus that was filling entire neuroplasm. The granule cells were aggregated in the form of clumps, and neuropil exhibited heterogeneous acidophilic masses containing fragments of nuclei and clear halos. Many granule cells were swollen in shape and size while some appeared darkly stained with dot like shrunken nuclei and empty spaces around them. In cerebral cortex of fluoride treated rat, the blood capillaries were congested with narrow lumen and perivascular empty spaces.
In cerebral cortex of the rats, treated with 100 ppm of sodium fluoride, there was disorganization of granular cell layer. The granule cells were accumulated in the form of clumps. Some pyramidal neurons showed chromatolysis (Fig. 2) and were shrunken with vacuolation around them (Fig. 4). The nuclei of some pyramidal neurons were eccentric in neuroplasm and others were showing necrosis. Some granule cells were swollen in shape and size (Fig. 5).
… In rats treated with 200 ppm of sodium fluoride, the blood capillaries were constricted with narrow lumen and perivascular empty spaces were observed in the cerebral cortex.
… Some glial cells appeared as darkly stained with dot like shrunken nuclei and empty spaces around them (Fig. 8).
… The neuronal degeneration and hypertrophy with perineuronal empty spaces were visible in the pyramidal neuron (Fig. 11). In cerebral cortex, some area showed necrosis with complete disintegration of neuropil accompanied by loss of glial cells (Fig.12).
… The pyramidal neurons in some area showed hyperchromatic and hypertrophic nucleus that was filling entire neuroplasm (Fig. 13). There were visible rounded fluid filled areas showing gliosis having debris of glial cells. The pyramidal neurons were distorted with spindle shape structure having elongated nucleus (Fig. 14).
In rats treated with 300 ppm of sodium fluoride, cerebral cortex contained the glial cells that were small, deeply stained and dot like structure with vacuolated areas around them (Fig. 15). The neuropil showed degeneration in the form of spiral structure surrounded by microglial cells (Fig. 16). At some locations eosinophilic neurons were visible in neuropil. Area of neuroplasm of some neuron was covered by darkly stained swollen large sized nucleus. Clear halos were visible around some neurons (Fig. 17). A few neurons exhibited degeneration at some locations in neuropil (Fig. 18). In some pyramidal neurons distorted nuclei were shifted to periphery. Chromatolysis visible in some granule cells (Fig. 19).