| Objective: To investigate the effects of low intensity pulsed ultrasound (LIPUS) on the apoptosis of chondrocytes in rabbits with osteoarthritis (OA) and explore the underlying mechanism. Methods: Thirty healthy New Zealand white rabbits were selected for this study. All the cultured cells were randomly divided into five groups: a normal control group (A group), an OA model group (B group), an OA model plus LIPUS group (C group), an OA model plus PI3K/Akt inhibitor group (D group), and an OA model plus PI3K/Akt inhibitor and LIPUS group (E group). The OA model was made by knee anterior cruciate ligament transection. At the 6th week after modeling, the rabbits were sacrificed by air embolism method and pathologic changes were assessed on articular surface of femoral condyles. Meanwhile chondrocytes were isolated and cultured in vitro, and cultured cells were identified by immuohistochemistry. The expression of collagen protein type Ⅱ, MMP-13, Akt, pAkt, P53, and Bcl-2 was detected by Western blotting. Results: As compared with the A group, the expression of collagen type Ⅱ, pAkt and Bcl-2 was significantly reduced in the B group, but that of MMP-13 and P53 was significantly increased in the B group (P<0.05). As compared with the B group, the expression of collagen type Ⅱ, pAkt and Bcl-2 was significantly increased, and that of MMP-13 and P53 was significantly reduced in the C group (P<0.05); the expression of collagen type Ⅱ, pAkt and Bcl-2 was significantly reduced (P<0.05), and that of MMP-13 and P53 was significantly increased in the D group (P<0.05). Although the expression of collagen type Ⅱ, MMP-13, pAkt, P53, and Bcl2 showed no significant difference between the E group and the B group, the expression of collagen type Ⅱ, MMP-13, pAkt, P53 and Bcl-2 showed significant difference between C group and D group (P<0.05). There was no significant difference in the expression of Akt among all groups. Conclusions: The LIPUS can obviously decrease the apoptosis rate of chondrocytes in the knee joints of OA rabbits via activating PI3K/Akt pathway, and the underlying mechanisms are closely related to upregulation of Bcl-2 expression and downregulation of P53 expression. The LIPUS can accelerate the recovery of cartilage for the purpose of treatment of OA. |
