Age changes in the rat temporomandibular joint articular disc: A biochemical study on glycosaminoglycan content

The temporomandibular joint (TMJ) articular discs were removed from female Sprague-Dawley rats 3, 5, 10, 32, 90 and 130 weeks of age. Glycosaminoglycans (GAGs) were extracted from the discs by heat treatment, alkali treatment and digestion with Pronase E, and purified by precipitation with cetylpyridinium chloride and ethanol. The concentration of total GAG was highest in the 3 week extracts and tended to decrease with age. Dermatan sulphate was the predominant GAG detected in all age groups along with chondroitin sulphate, hyaluronic acid and heparan sulphate. The disaccharides obtained from chondroitin sulphate were Delta Di-4S, Delta Di-6S and Delta Di-0S, with Delta Di-4S being the predominant isomer followed by Delta Di-6S for all ages of all the GAG examined. The concentration of chondroitin sulphate showed a decrease with age. Quantitative changes of GAG with age may be related to functional changes in TMJ discs.