Degenerative
joint disease was induced in the knee joints of mice by
intraarticular injection of two different stimuli: iodoacetate and highly purified
collagenase.
Proteoglycan synthesis was measured in vivo at different time points in four topographical areas of the knee joint (central and peripheral parts of the patella and central parts of the medial and lateral tibial plateaus) and was compared with histological observations of localized damage to the joint. In vitro incubation with iodoacetate had a direct effect on
proteoglycan metabolism.
Intra-articular injection of iodoacetate in vivo inhibited the
proteoglycan synthesis in cartilage from the central part of the patella. In the peripheral part of the patella, inhibition on day 1 was followed by stimulation of synthesis on days 3-30.
Proteoglycan synthesis also was inhibited in the central parts of the medial and lateral tibial plateaus. The areas with inhibited synthesis had loss of
safranin O staining on histology. In vitro incubation with
collagenase did not have a direct effect on the
proteoglycan metabolism of intact cartilage; this led to the assumption that
osteoarthritis after injection of
collagenase is caused by ligamentous injury, which leads to an unstable joint. Injection of
collagenase in vivo stimulated the
proteoglycan synthesis in cartilage from the central and peripheral parts of the patella. In an early stage of the process, the cartilage from the tibial plateaus also was slightly stimulated.(ABSTRACT TRUNCATED AT 250 WORDS)