| Objective: To study the articular cartilage and subchondral bone effect andmechanism of the early intervention of calcitonin (CT) on knee osteoarthritis (OA) ratmodel induced by anterior cruciate ligament transection (ACLT).Methods: The30male SD rats of clean grade were randomized into the three groups:sham operation group (sham group); anterior cruciate ligament transection+saline group(ACLT group); anterior cruciate ligament transection+CT group (ACLT+CT group),10rats per group. On the rat right knee, the ACLT were implemented. The CT weresubcutaneously injected by the dose of5IU/kg after operation in the ACLT+CT group andthe same volume of normal saline were subcutaneously injected in the ACLT group. Theknee joint cavity was opened and ACLT was not implemented in the Sham group. On the12weeks after operation, the all rats were sacrificed. The right knee joint cavity wasopened, observed the general situration of knee cartilage. The samples of rat femoral werefixed and stained by toluidine blue and type II collagen immunohistochemical staining, andthen measured the average gray values. Using the IPP sofeware, the morphometry anddynamic parameters of subchondral bone tissue were done by quantitative analysis.Results:1. The general observation of rat articular cartilage surface in each group: Thearticular cartilage surface was smooth and complete in the Sham group; The cartilage wasdark red with larger ulcer area and cartilage edge with osteophytes in the ACLT group;The articular cartilage surface was less smooth with rough cartilage surface and ulcer inlocal sections.2. The staining of toluidine blue and tchemical ype II collagenimmunohistochemical staining in each group: The rat joint was colored dark blue withuniformity dying, the smooth surface, the orderly cartilage cell arragement and clearhierarchy were observed in Sham group. The extracelluar matrix of cartilage was brownand the shallow cartilage cells staining was positive by immunohistochemical staining inthe Sham group. In ACLT group, the toluidine blue staining was mostly loss of levelstaining, the obviously decreasing of cartilage cells and the disorderly arragement were observed. The cartilage cells were disappeared and only small expression of type IIcollagen by immunohistochemical staining in the ACLT group. The shallow color wasmore shallow, the fibrosis of superficial cartilage, not orderly arragement of cartilage cells,the stillly clear of levels were observed in the ACLT+CT group. The cartilage layer wasthinner, small amount of chondrocytes were stainned, the extracellular matrix coloring wasrelatively lighter by immunohistochemical staining in the ACLT+CT group.3. The structure parameters of subchondral bone histomorphometry in eachgroup: compared with the Sham group, the BV/TV, Tb.Th, Tb.N were significantlydecreased and theTb.Sp was obviously inceased in the ACLT and ACLT+CT groups withstatistical difference (P<0.05); compared with the ACLT group, the BV/TV, Tb.Th, Tb.Nwere significantly increased and theTb.Sp was obviously deceased in the ACLT+CT groupwith statistical difference (P<0.05).4. The dynamic parameters of subchondral bone histomorphometry in eachgroup: compared with the Sham group, the MS/BS, MAR, BFR/BS was obviouslydeceased in the ACLT and ACLT+CT groups with statistical difference (P<0.05);compared with the ACLT group, the MS/BS, MAR, BFR/BS were significantly increasedin the ACLT+CT group with statistical difference (P<0.05).5. The comparison of phosphorylation of ERK1/2in chondrocytes of eachgroup: compared with the Sham group, the phosphorylation level of ERK1/2wasobviously inceased in the ACLT and ACLT+CT groups with statistical difference(P<0.05); compared with the ACLT group, the phosphorylation level of ERK1/2wassignificantly decreased in the ACLT+CT group with statistical difference (P<0.05).Conclusion:1. The CT by subcutaneously injection can stimulate the synthesis of type IIcollagen and reduce the injury of knee articular cartilage in the knee osteoarthritis ratmodel induced by ACLT.2. The CT by subcutaneously injection can improve the subchondral trabecularmicrostructure and maintain the biomechanical properties of bone under cartilage in theknee osteoarthritis rat model induced by ACLT.3. The CT can inhibite the rat knee osteoarthritis induced by ACLT through theregulation of p-ERK1/2expression of MAPKs pathway. |
