Abstract
OBJECTIVE: This study aims to investigate changes in matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinase (TIMP) levels in the intervertebral discs of New Zealand white rabbits under simulated overload and microgravity conditions, focusing on the expression of MMP1, MMP3, and TIMP1. The findings aim to provide a theoretical foundation for preventing and delaying lumbar disc degeneration in these environments. METHODS: Overload was simulated using an animal centrifuge, and microgravity was mimicked through tail suspension. A randomized single-blind method was applied to divide 120 age- and weight-matched New Zealand white rabbits into six groups: control groups (30 d, 60 d, 90 d) and overload/microgravity groups (30 d, 60 d, 90 d), with 20 rabbits per group. The expression of MMP1, MMP3, and TIMP1 in the lumbar intervertebral discs was measured and analyzed using statistical methods, including chi-square tests and t-tests, across different exposure times. RESULTS: In the experimental groups, MMP1 and MMP3 expression levels were significantly higher than those in the corresponding control groups at all time points (P < 0.01). MMP1 and MMP3 levels progressively increased with longer exposure durations, showing statistically significant differences (P < 0.01). TIMP1 expression was significantly higher in the 30-day and 60-day experimental groups than in the control group (P < 0.01), but decreased in the 90-day group, indicating a late-stage imbalance in the MMP/TIMP1 ratio. CONCLUSION: Simulated overload and microgravity conditions lead to elevated MMP1, MMP3, and TIMP1 expression in lumbar intervertebral discs, promoting accelerated disc degeneration.