The Expression And Role Of Serum NO,OPG And RANKL In Rat Tibial Tissue During Sports Bone Injury Occurred

Purposes:Overtraining or excessive using lead to susceptibility of skeletal injuries increased, and the sports bone injury was induced by mechanical stress. Sports bone injury is one of the stress fracture which is a thorny issue that plagued athletes and coaches, the specific mechanism of sports bone injury occurred remains unclear. This study established an animal model of sports bone injury that was made by using large load jump exercise. Serum biochemical markers of bone, nitric oxide, the expression of of OPG and RANKL mRNA were investigated exploring molecular changes in its internal relations when the sports bone injury occurred.Methods:48-month-old male SD rats, divided into a contrast group and jump group (n=24) randomly. Jumping rats placed homemade jumps electrical stimulus cage with big load jump training, the contrast group was quiet feeding,sacrificed8rats from two groups every two weeks respectively of rats, ended the experiment in6weeks. Each time the the derived experimental blood, colorimetric detection of bone metabolic biochemical markers alkaline phosphatase (AKP) and tartrate-resistant acid phosphatase (StrACP) in serum,using the chemical assay detect the activity of NO and NOS.Results:(1) The jumping group AKP activitywere higher in the first two weeks and four weeks (p<0.05), and after jumping six weeks the activity was significantly higher than the contrast group (p<0.01). Compared with the contrast group, StrACP was very increased significantly in2,6weeks jump group (p<0.01), and jump4weeks group was higher significantly (p<0.05).The increased range was consistent in2,4weeks jump group, while6weeks jump group sharpest.(2)2weeks jump group NO levels tended to increase, but not statistically significant (p>0.05),4weeks jump group NO levels were significantly higher (p<0.05). while the4weeks jump group NO levels was sharpest, with a very significant difference (p<0.01), serum iNOS activity decreased at6weeks, and found no correlation with the presence of NO.(3) After jumping stimulation2weeks, rat tibia OPGmRNA expression levels slight decrease (p<0.05).Jumping stimulation4weeks, OPGmRNA express rebound, comparing with contrast group has no difference,after6weeks jumping, OPGmRNA expression were higher significantly (p<0.01).2weeks and4weeks jump groups, the rat tibia RANKLmRNA expression increased, but there was no significant different. RANKL mRNA expression levels increased significantly in6weeks jump group (p <0.01).(4) Jump group serum NO levels have correlation with the mRNA expression of OPG and RANKL,serum AKP activity, the correlation coefficient r=0.819(p <0.01), and0.864(p<0.01) and0.536(p<0.05).High correlation between OPG mRNA to RANKLmRNA (r=0.947, p<0.01).There is a high correlation between the mRNA expression of OPG\RANKLand AKP (r=0.615, p<0.01;r=0.565, p <0.01.Conclusions:(1) NO was sensitive to bone formation, with a correlation to the biochemical indicators AKP,NO linked with stress-induced bone destruction.(2) The excessive stress stimulation resulted in increased expression of OPG\RANKLmRNA, is one of the sports bone injury mechanism.(3) NO is an important upstream factor ofOPG\RANKL\RANK signaling pathway systems.