[Expression and significance of AKT/mTOR signaling pathway in natural degeneration in vitro model of endplate chondrocytes of rats]

Abstract

Objective: To investigate the expression and significance of AKT/mTOR signaling pathway in natural degeneration in vitro model of rat endplate chondrocytes.

Methods: Rat endplate chondrocytes were isolated and cultured, and the natural degeneration in vitro model of rat endplate chondrocytes was established. The endplate chondrocytes were divided into blank control group (P2 cells), natural degeneration passage group (P5 cells), AKT/mTOR signaling pathway inhibitor group (P5 cells), AKT/mTOR signaling pathway agonist group (P5 cells). The endplate chondrocyte morphology changes were observed under inverted microscope; Toluidine blue staining was used to detect the expression changes of proteoglycans in endplate chondrocytes; Western blot was used to detect the expression changes of AKT and P-AKT; real-time polymerase chain reaction was used to detect the expression of type Ⅱ collagen, proteoglycan, SOX9 and the key gene of AKT/mTOR signaling pathway, mTOR gene.

Results: With in vitro passage of rat endplate chondrocytes, phenotypes of rat endplate chondrocytes gradually reduced or even lost; the type Ⅱ collagen (P5/P2=0.28, P=0.042 7), proteoglycan (P5/P2=0.33, P=0.026 3), SOX9 (P5/P2=0.40, P=0.018 2) and mTOR (P5/P2=0.28, P=0.038 1) expression were significantly reduced in natural degeneration passage group; in AKT/mTOR signaling pathway inhibitor group: type Ⅱ collagen (P5/P2=0.19, P=0.034 7), proteoglycan (P5/P2=0.25, P=0.023), SOX9 (P5/P2=0.31, P=0.034 2) and mTOR (P5/P2=0.20, P=0.024 1) expression were decreased compared with natural passage group; in AKT/mTOR signaling pathway agonist group: type Ⅱ collagen (P5/P2=0.41, P=0.044 1), proteoglycan (P5/P2=0.53, P=0.015 1), SOX9 (P5/P2=0.61, P=0.019 7) and mTOR (P5/P2=0.41, P=0.038 1) expression were increased compared with natural passage group and inhibitor group.

Conclusion: AKT/mTOR signaling pathway may play an important role in the degenerative process of rat endplate chondrocytes in vitro, artificial control or intervention of AKT/mTOR signaling pathway may accelerate, inhibit or slow the degeneration of endplate cartilage of rats.