[Effect of neurotropin on experimental osteoarthritis]

The effect of Neurotropin on osteoarthritis was investigated in comparison with those of prednisolone and indomethacin. 1) There were remarkable decreases in the staining intensity to safranin-O and in the contents of uronic acid, total hexosamine and hexose in the articular cartilage of rabbits in which experimental osteoarthritis was induced by the injection of papain into the knee joint. In the Neurotropin-treated group, the decrease in the staining intensity to safranin-O and the contents of uronic acid, total hexosamine and hexose were evidently recovered. On the other hand, in the prednisolone- or indomethacin-treated group, the degeneration of the cartilage was even more pronounced than in the control group treated with papain alone. 2) Neurotropin had no effect on the autolytic degradation of cartilage, but promoted the incorporation of 14C-acetate into the proteoglycan in the articular cartilage of rabbits. 3) Both prednisolone and indomethacin inhibited the autolytic degradation and the incorporation of 14C-acetate into the proteoglycan. These results suggested that the therapeutic effect of Neurotropin on osteoarthritis may be due to the improvement of decreased proteoglycan content in the matrix of articular cartilage; and in this respect, it is different from anti-inflammatory drugs such as prednisolone and indomethacin.