RESUMO
Previous studies have indicated that chronic intermittent hypobaric hypoxia (CIHH) preconditioning can inhibit TNFα and other related inflammatory cytokines and exerts protective effect on intervertebral disc degeneration disease (IDD) in rats; however, the mechanism is still unclear. The present study aimed to explore the repair mechanisms of CIHH on IDD in rats. In the experiment, 48 adult SpragueDawley rats were selected and randomly divided into an experimental group (CIHHIDD), a degenerative group (IDD) and a control group (CON). The CIHHIDD group of rats (n=16) were treated with CIHH (simulated 3000 m altitude, 5 h per day, 28 days; PO2=108.8 mmHg) before disc degeneration surgery. The IDD group of rats (n=16) underwent tailvertebral intervertebral disc surgery to establish a model of intervertebral disc degeneration. The CON group of rats (n=16) did not receive any treatments. After surgery, the disc height index was calculated using Xray analysis of rat tail vertebrae, the degeneration process was observed and repair was evaluated by chemically staining degenerative intervertebral disc tissue slices. The expression levels of basic fibroblast growth factor (bFGF), TGFß1, Collagen I and Collagen II were measured in the intervertebral disc tissue using western blotting; while the expression levels of bFGF, TGFß1 and hypoxiainducible factor 1α (HIF1α) were measured in rat serum using ELISA. The results demonstrated that: i) The degree of intervertebral disc height degeneration in CIHHIDD rats was significantly lower compared with that in IDD rats (P<0.05); ii) the expression levels of bFGF, TGFß1 and HIF1α were higher in CIHHIDD rat serum compared with those in IDD rat serum (P<0.05); iii) optical microscopy revealed that the degree of disc degeneration was relatively mild in CIHHIDD rats; and iv) the protein expression levels of bFGF, TGFß1 and collagen II were increased in CIHHIDD rat intervertebral disc tissues compared with those of IDD rats, while the overexpression of collagen I protein was inhibited. Overall, after CIHH pretreatment, the expression levels of bFGF and TGFß1 were upregulated, which play notable roles in repairing degenerative intervertebral discs in rats.