Histopathological investigation of fluoride-induced neurotoxicity in rabbits.

Abstract

SUMMARY: Brain tissues for neurohistopathological study were obtained at

autopsy from albino rabbits that had been subcutaneously injected for 15

weeks with 0, 5, 10, 20, and 50 mg of sodium fluoride in 1 mL of aqueous solu-

tions/kg bw/day. Neuropathological changes occurred with loss of the mo-

lecular layer and glial cell layer in the brain tissues of rabbits exposed to the

three higher fluoride doses. The Purkinje neurones exhibited chromatolysis

and acquired a “ballooned” appearance. Nissl substance showed various de-

grees of decrease and even complete loss. Fragmented particles were re-

tained in the perinuclear zone. The perikaryon showed vacuolization, and

spheroid bodies were present in the neuroplasm. These cytoplasmic inclu-

sions appeared as various sized ovoid bodies or elongated eosinophilic

masses due to which the nucleus was shifted to the periphery. These neuro-

toxic changes in the brain suggested that there was a direct action of fluoride

upon the nerve tissue which was responsible for central nervous system

problems such as tremors, seizures, and paralysis indicating brain dysfunc-

tion seen at the two highest doses.