Effect of herbs with function of reinforcing kidney and replenish marrow on mRNA and protein expression of Runx2 in bone tissue of rats with glucocorticoid-induced osteoporosis

Objective To observe the mRNA and protein expression of Runx2 in the bone tissue of the rat models with glucocorticoid-induced osteoporosis(GIOP) and discuss the pathogenesis of GIOP and the therapeutic effect and adjustable function of the herbs with the function of reinforcing the Kidney to replenish marrow.Methods We established the GIOP rat models by hind limb intramuscular injection of dexamethasone(2.5 mg /kg,twice a week,9 weeks continuously).We stratified all the rats by different body weight and then divided them randomly into normal group,blank model group,reinforcing the Kidney to replenish marrow herbs group,reinforcing the middle to benefit qi granula group,removing blood-house stasis capsule group and GUSUKANG granula positive control group.We administrated them by gavage for 9 weeks.We detected the femur bone mineral density by using the XR-26 dual energy X-ray absorptiometry to evaluate the establishment of the animal model and the therapeutic effect of the drugs.We detected the mRNA expression of Runx2 in the bone tissue by Real-Time Quantitative RT-PCR and detected its protein expression by Western blot.Results(1) femur bone mineral density: compared with normal group,blank model group decreased significantly(P 0.01);compared with blank model group,reinforcing the Kidney to replenish marrow herbs groupincreased significantly(P 0.01),GUSUKANG granula positive control group increased significantly(P 0.05),reinforcing the middle to benefit qi granula group and removing blood-house stasis capsule group both tended to increase,but neither of their difference had statistical significance (P 0.05).(2) mRNA and protein expression of Runx2 in the bone tissue: compared with normal group,blank model group decreased significantly(P 0.01);compared with blank model group,reinforcing the Kidney to replenish marrow herbs groupup-regulated significantly(P 0.01),GUSUKANG granula positive control group also up-regulated significantly(P 0.05),reinforcing the middle to benefit qi granula group and removing blood-house stasis capsule group both tended to increase,but neither of their difference had statistical significance(P 0.05).Conclusions(1) The GIOP rat models can be established successfully by intramuscular injection of dexamethasone.(2) Maybe it is one aspect of the pathogenesis of GIOP that the level of the mRNA and protein expression of Runx2 in the bone tissue decreases.(3) The reinforcing the Kidney to replenish marrow herbs have more evident preventative and therapeutic effect on GIOP by upregulating the mRNA and protein expression of Runx2 in the bone tissue than the strengthening the spleen herbs and the promoting blood circulation herbs.