[Joint loading as a possible etiology for arthrosis development. Results of animal experiment studies of the rat...

We review our results with an animal model for investigations on the development of osteoarthritis (OA). This model is based on running exercises of wistar rats performed in a running wheel using intracranial self-stimulation to motivate rats to excessive running. In our studies a total of 49 rats was divided into groups with running exercises of 15 km, 20 km, and 30 km respectively. In order to investigate the influence of altered sensible joint innervation on the development of OA, in addition to a total running load of 20 km in another group of 8 rats we performed Capsaicin (8 Methyl-N-vanillyl-6-noneamide) mediated partial sensible knee joint denervation. Complete knee joint sections of all rats were evaluated histologically using Mankins grading system. In addition, we performed semiquantitative assessment of the immunoreactivity of the chondrocytes to MMP-3 by immunostaining with monoclonal MMP-3 IgG antibodies. Histological assessment and immunostaining for MMP-3 of the knee joint sections revealed a significant increase in osteoarthritic changes with higher running load. Moreover, osteoarthritic changes in the knee joints of the rats with sensible joint denervation and running exercises were significantly greater as compared to those with sole running load. In conclusion, our studies revealed a significant relationship between the development of knee osteoarthritis and the extent of joint load. Hereby, an alteration of the sensible joint innervation seems to have a promoting effect on the development of osteoarthritic changes. This model offers a wide range of further approaches to studying different processes of the development of OA.