Effect of aging on the production and the action of nitric oxide in articular cartilage

Im, Gun Il; Shin, Sung Ryong; Kim, Do Young; Shin, Joo Ho; Cho, Won Ho

Abstract

PURPOSE
We investigate the age-related changes in the production of nitiric oxide (NO) in the articular cartilage and its effects on cell proliferation.
MATERIALS AND METHODS
Forty New Zealand white rabbits of four different age groups were used. There were 10 rabbits in each group and the age groups were 1 month, 6 months, 1 year and 3 years of age. We measured the basal and induced production of NO in cultured articular chondrocytes that were obtained from distal femur by using a nitrite assay. We observed the changes in the proliferative activity of the chondrocytes after exogenous NO administration using a nonradioisotopic proliferation assay. In addition, we also detected endothelial nitric oxide synthase (eNOS) in articular cartilage using immunohistochemical staining.
RESULTS
The basal and induced levels of NO were lower in the cultured chondrocytes from older rabbits. Exogenous NO administration suppressed the proliferative activity of chondrocytes to a greater degree in the younger rabbits than in the older ones. Immunohistochemistry showed a predominance of eNOS positive chondrocytes in the superficial layer. The number of eNOS positive chondrocytes decreased in older rabbits.
CONCLUSION
The production of NO decreased with aging in normal articular cartilage. The suppression of proliferative activity in chondrocytes by exogenous NO declined with aging.