Objective To investigate the dynamic changes of articular cartilage destruction and nitric oxide nitric oxide/inducible nitric oxide synthase (NO/iNOS).Methods Forty healthy adult male Wistar rats were randomly divided into control group (free movement) and experimental group (overtraining).Total knee joints of rat were collected at week 0,1,2,3,and 6,fixed with 4％ PFA,embedded in paraffin,sectioned and stained.Cartilage morphological changes were observed by Safranin-O staining,NO/iNOS content changes in serum and synovial fluid were determined by ELISA,Mankin's scores were obtained,and cartilage pathological changes were analyzed.Results Overtraining resulted in cell sorting disorders,loss of matrix,destruction like rough surface and cracks,and degeneration of cartilage pathology process.Levels of NO/iNOS in serum and synovial fluid increased after overtraining:week 1 (48.088 ± 1.534),(3.058 ± 0.073);week 2 (54.574 ± 0.800),(6.630 ± 0.524);week 3 (68.020 ± 3.184),(7.384 ± 0.306);weeks 6 (104.394 ± 8.094),(11.364 ± 0.882) Levels of NO/iNOS in synovial fluid group were:week 1 (65.814 ±1.610),(8.126 ±0.724);week 2 (72.766 ± 2.344),(9.694 ± 0.564);week 3 (88.816 ± 0.819),(11.326 ± 1.473);week 6 (120.204 ± 12.044),(15.166 ± 1.198),and high level of concentration was found with the increasing amount of exercise.Conclusion There is a positive correlation between the levels of NO/iNOS in synovial fluid or serum and the extent of the damage of articular cartilage.

Objective To explore the proliferative changes and clinical significance of osteoclasts (OC) in various stages of osteoarthritis (OA). Methods Twenty healthy adult male SD rats were made the model by modified Hulht procedure,the left knee served as the control group and the right knee as the OA model group. The total knee joint (n=5) was collected at postoperative 1, 2,4,8 weeks, fixed at 4 ℃ 4% poly formaldehyde (PFA) liquid, embedded by paraffin for conducting sections, and stained by TRAP,toluidine blue(TB) and safranine O (Saf O)fast staining. Then the cartilage morphology change was observed and OC positive cells number with TRAP staining were semi-quantitatively detected,the OA cartilage destruction progression was evaluated by Mankin's method and SPSS17.0 statistics software was used to conduct statistical analysis. Results OC in the two groups showed the transient change of rapidly increasing and then decreasing. The OC number at 1 week in the control group (left knee) was (65.20±4.12) cells/mm2 ,and was gradually reduced at 2,4 weeks,which were (47.20±4.31) cells/mm and (26.20±3. 87) cells/mm2 ,which at 8 weeks was almost invisible, the number of cells was (7.00 ± 2.28) cells/mm2 ;the OC number at 1 week in the OA model group (right knee) was (70.40 ± 5.46) cells/mm2 ,increased to (86.20± 5.42)cells /mm2 at 2 weeks, reduced to (38. 0 ± 3.16) cells/mm2 at 4 weeks , was almost invisible at 8 weeks, the number of cells was (6.21 ± 2.93 ) cells/mm2 . The OC number at 2,4 weeks in the model group was significantly higher than that in the control group, the difference had statistical significance (P<0.05). Conclusion Large numbers of osteoclasts are proliferated in the early and middle stages of rat knee osteoarthritis, which indicating that OC might be involved in the formation of osteoarthritis.