Effect of loading and prednisolone treatment on the glycosaminoglycan content of articular cartilage in dogs.

The effect of prolonged prednisolone administration on glycosaminoglycan components was studied by means of determinations of galactosamine, glucosamine, uronic acid, sulphate and sialic acid content in normally loaded and spared articular cartilages of the knee-joints in dogs. After 40 days, all glycosaminoglycan components decreased by 58% in the spared cartilage, as compated with the controls. Prolonged administration of 0.5 mg prednisolone/kg body weight (corresponding to a low therapeutic dose), elicited a further decrease in galactosamine, whereas the other components remained practically unchanged. In the normally loaded articular cartilage of prednisolone-treated dogs the glycosaminoglycan components decreased by about 11-31% compared with untreated controls. The quantitative data indicate that in the changes occurring the glycosaminoglycan composition of the articular cartilage due to relief of function and to prednisolone treatment, chondroitin suplphate is mainly involved. The changes due to prednisolone treatment are dependent on the functional demand of the joint.