Connective Tissue Metabolism in Bone and Cartilage of Adjuvant Arthritic Rat

Abstract

The metabolism of connective tissue matrix components such as glycosaminoglycans and glycoproteins was investigated in normal as well as pathological tissues of bone and cartilage associated with adjuvant arthritis using rat as animal model of the disease. The inflammatory process of adjuvant arthritis was induced in rats with the inoculation of Freund's adjuvant containing heat killed Mycobacterium tuberculosis suspended in paraffin oil. The changes in the metabolism of matrix components in bone and cartilage were examined using radioactive isotopic labeling measurements during the acute as well as chronic phases of arthritic disease. The glycosaminoglycans were fractionated into sulfated and non-sulfated glycosaminoglycans by chemical and enzymic modifications. The biosynthesis of sulfated glycosaminoglycans was evaluated using radioactive labeled (35S)-sulfate. Alterations were demonstrated in the metabolism of connective tissue in the bone and cartilage tissues of arthritic rat. The results obtained showed an increased incorporation of radioactive sulfate in specimens of bone and cartilage during the process of adjuvant arthritis. The contents of sulfated as well as non-sulfated glycosaminoglycans were found to be increased in both the tissues of arthritic rat. Similarly, the amount of total glycosaminoglycans was also found to be increased significantly in the diseased tissues. In addition, various components of tissue glycoproteins such as fucose, sialic acid and total hexose were found to be elevated in insoluble fractions of bone and cartilage during the diseased state. The effects of experimentally induced adjuvant arthritis on the connective tissue were discussed in the light of changes taking place in the metabolism of glycosaminoglycans and glycoproteins in bone and cartilage of arthritic rat.