Effects of Fluoride on Rachitic Rats

Abstract

Both vitamin D-deficient diet and fluoride intake affect calcified tissues and parathyroids in growing rats. Studies were designed to investigate effects of low fluoride intake on rachitic rat femoral bones and parathyroids. Holtzman rats placed on rachitic diet were given distilled water to which 4 , 8, and 20 ppm fluoride a s NaF was added. Control groups consisted of rats on normal laboratory diet and tap water, normal diet and fluoride-treated water, and rachitic diet and tap water. Tetracycline was administered to all groups 5 and 15 days before sacrifice. Animals were provided with these diets and appropriate waters ad libitum until sacrificed after 4 weeks treatment. Parathyroids were removed and prepared for routine paraffin sectioning. Femurs were removed and prepared for routine frozen and paraffin sectioning. Naphthol AS-BI phosphoric acid was used a s substrate for Burstone\u27s method of acid and alkaline phosphatase activity. Bone and parathyroid sections were stained with H & E and PAS. Compared with rachitic control rats , f luoride-treated rachitic rats showed: (1) a slight decrease in body growth rate, and femur weight and length: (2) a slight increase in diaphysial cortical thickness: (3) no change in either phosphatase activity: (4) a decrease in distance between periosteal tetracycline labels: (5) no apparent histological change in parathyroids: and (6) no marked change in size or numbers of femoral diaphysial resorption spaces. These observations indicate that at these dosages, fluoride: (1) caused delayed rate of periosteal bone mineralization measured by tetracycline labels. As the fluoride dosage increased, distances between labels markedly decreased. (2) had no apparent effect on either phosphatase enzyme activity. Activity was seen at periosteal and endosteal surfaces, and in cortical resorption spaces. Activity increased over normal controls, but was similar to those of rachitic controls