Histochemical Study of Bone in Hydrocortisone- and Fluoride-Treated Rats

¹ Department of Anatomy, School of Medicine, University of Southern California, Los Angeles, California, and National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland

Sixty female rats were given daily intramuscular injections of 2.5 mg. of hydrocortisone acetate for 30 days. In second group, 60 similar rats were given injections of the vehicle in which the corticosteroid was suspended, and thus acted as controls. Thirty rats in each of these groups received either distilled water or drinking water that contained 75 ppm F. Histologic sections of both the tibias and jaws from rats in all groups were stained by various histochemical methods to determine the influence of hydrocortisone or fluoride, or both, on the calcification of the bone. There was loss in body weight and extreme narrowing of the epiphyseal cartilage of the tibias of rats treated with hydrocortisone or hydrocortisone and fluoride. Although the body weight and width of the fluoride-treated rat were similar to those of the control animal, the morphologic structure of the epiphyseal cartilage was different. The trabeculae from rats treated with fluoride, hydrocortisone, or hydrocortisone plus fluoride stained deep red with PAS stain and exhibited an abundance of Alcian blue-positive material, which also stained intense violet with toluidine blue. These staining reactions would indicate that there was an alteration in the ground substance of both bone and cartilage. This situation produced an interference in the calcification of the bone. Intramembraneous ossification, as well as endochondral ossification, was affected, as exemplified by the interradicular bone of the molar teeth, which also showed similar changes.