ABSTRACT
Sodium fluaride is known as a specific and effective dental caries rohylactic agent and its systemic or local application is widely recommended in the recent years. It is also used as antihelminthic against roundworms, and for treatment of osteoporosis and otosclerosis in conjunction with calcium supplements and vitamin D. Moreover, it is used for water fluoridation, and as a rodenticide, disinfectant and fungicide. In recent years, acute and chronic toxicity of fluoride has been reported. The purpose of the recent study was to shed light on the histological [light and electron microcopic] and histochemical changes that might occur in the proximal and distal convoluted tubules of the renal cortex of albino rats following acute and chronic sodium fluoride [NaF] toxicity and to investigate the possible protective effect of sodium selenite [Na[2]SeO[3] administration on such toxicity. The present study was carried out on 80 adult male albino rats. They were divided into two main groups: acute NaF toxicity group and chronic NaF toxicity group, each of them included forty rats and was divided equally into four groups which were control group, NaF group, Na[2]SeO[3] group, and NaF and Na[2]SeO[3] group. In the acute toxicity group, NaF group received a single oral dose or NaF [135mg/kg body weight], Na[2]SeO[3] group received a single oral dose of Na[2]SeO[3] [0.35mg/kg body weight/day], while NaF and Na[2]SeO[3] group received a single oral dose of NaF [135mg/kg body weight] simultaneously with a single oral dose of Na[2]SeO[3] [0.35 mg/kg body weigh/day]. On he other hand, in chronic toxicity group, NaF group received NaF orally in a dose of 6mg/kg body weight/day, Na[2]SeO[3] group received Na+2+Se[SeO[3] orally in a dose of 0.35 mg/kg body weight/day, while NaF and Na+2+SeO[3] group received a daily oral dose of NaF [6mg/kg body weight/day] simultaneously with a daily oral dose of Na[2]SeO[3]]0.35mg/kg body weight/day] for three months. All rats were sacrificed 24 hours after their last dosing by decapitation after ether anesthesia Fresh specimens were taken from the renal cortex of each rat and prepared for the histological study [light microscopic examination using haematoxylin and eosin stain, and electron microscopic examination using the transmission electron microscope], and histochemical study [Periodic Acid-Schiff reaction]. The results of the present study revealed that there were marked histological and histochemical changes in the convoluted renal tubules following acute and chronic NaF toxicity. Moreover, sodium selenite was found to be a safe anti-oxidant, when used in appropriate dose, which could offer protection for the renal tissue in chronic NaF toxicity. Hence, it is recommended as a prophylactic agent given to workers highly exposed to sodium fluoride in their work place