PROTEIN-KINASE-C ACTIVATOR INHIBITS PROGRESSION OF OSTEOARTHRITIS INDUCED IN RABBIT KNEE JOINTS

To study the role of protein kinase C (PKC) in cartilage tissue in ost eoarthritis, experimental osteoarthritis was induced in the knee joint s of rabbits by resection of the anterior cruciate ligament (ACL). At 4 weeks after the operation, osteoarthritic changes varying from surfa ce irregularities and cleft formation to loss of the tangential layer were observed, and cloning or hypocellularity of the chondrocytes was observed mainly in the transitional and radial layers. The PKC activat or 12-o-tetradecanoyl-phorbol-13-acetate (TPA) or non-PKC-activating p horbol ester 4 alpha-phorbol-12,13-didecanate (PDD) was administered i ntraarticularly once a week from the day of the operation for 3 weeks. Histologic evaluation with a rating scale was carried out. In the TPA -administered group, cartilage structures were preserved almost comple tely, and score of the cartilage lesion was significantly less than th at in animals administered PDD or in nonadministered controls. A chond roprotective role of PKC under mechanical stress was suggested.