Effect of Low-Intensity Pulsed Ultrasound on Extracellular Matrix and MAPKs Signaling Pathways in Early and Medium Term of Rabbit Knee Osteoarthritis Model
We established a rabbit osteoarthritis model by anterior cruciate ligament transaction and observed the articular cartilage repair effect of low-intensity pulsed ultrasound irradiation. Thirty-six healthy New Zealand rabbits were randomized into early control group, early osteoarthritis group, early treatment group, medium-term control group, medium-term osteoarthritis group and medium-term treatment group. Animals in early control group and medium-term control group underwent articular capsulotomy surgery, and those in other four groups underwent anterior cruciate ligament transaction. In early osteoarthritis group and early treatment group, rabbits received low-intensity pulsed ultrasound irradiation 3 days after surgery, while in medium-term osteoarthritis group and medium-term treatment group irradiation received at the beginning of the fifth week after surgery. However, ultrasound irradiation of early osteoarthritis group and medium-term osteoarthritis group was no output. Six weeks after irradiation, the rabbits were sacrificed and pathologic changes in the articular surface of femoral condyle were assessed. Also, expression of type II collagen, proteoglycan, phophorylated extracellular signalregulated kinase1/2 and p38 of the articular cartilage was measured by Western blot. The result shows that low-intensity pulsed ultrasound intervention is beneficial to articular cartilage repair by abating damage of extracellular matrix in early term of osteoarthritis and extracellular signal-regulated kinase1/2 and p38 signaling pathway was involved.