Effects of hyperbaric oxygen on serum MMP-2 and MMP-9 levels and spinal cord edema in rats with spinal cord injury

Abstract

Objective To observe the effects of hyperbaric oxygen (HBO) on the levels of serum MMP-2 and MMP-9 in rats with spinal cord injury,and also to investigate the effects of HBO intervention on spinal cord edema following acute spinal cord injury (SCI).Methods Ninety-six healthy adult SpragueDawley rats were randomly divided into 4 groups:the sham group,the sham + HBO group,the SCI group and the SCI + HBO group.And the 4 groups were further divided into the h 24,h 48,h 72 and d 5 subgroups,each consisting of 6 rats.The expression levels of serum MMP-2 and MMP-9,interleukin (IL-6),vascular endothelial growth factor (VEGF) and water content in the spinal cord were monitored with ELISA.Results When compared with those of the sham group and the sham + HBO group,the levels of serum MMP-2,MMP-9 level and water content in the spinal cord increased significantly,with statistical significance (P ＜ 0.01).When compared with that of the SCI group[(128.97 ±22.39) μg/L],serum content of MMP-2 in the rats of the SCI +HBO group[(84.26 ± 12.20)μg/L] displayed a statistical significance at h 72 (P ＜ 0.05).When compared with that of the SCI group[MMP-2 h 72:(128.97 ±22.39) μg/L; MMP-9 h 48:(56.07 ±7.96) lg/L,h 72:(53.54 ±6.80) μg/L,h 120:(42.85 ±6.57) μg/L],serum contents of MMP-9 at h 48,h 72 and h 120 in the rats of the SCI + HBO group [(47.08 ± 4.98)、(44.77 ± 6.58)、(35.36 ± 5.72) μg/L] also displayed a statistical significance (P ＜ 0.05).Compared with that of the SCI group,water content in the spinal cord in the animals of the SCI + HBO group displayed a significant difference at h 48 and h 72,with a statistical significance (P ＜ 0.05),and very significant difference could be noted at d 5 (P ＜ 0.01).Levels of serum MMP-2 (P ＜0.05) and MMP-9 (P ＜ 0.01) were positively correlated with the water content in the spinal cord.Conclusions HBO intervention could down-regulate serum levels of IL-6,MMP-2 and MMP-9,and upregulate the levels of VEGF,alleviating spinal cord edema,stabilizing blood-spinal cord barrier,and in one way or other promoting repair of nerve function of the rats following spinal cord injury. Key words: Hyperbaric oxygen; Spinal cord injury; MMP-2; MMP-9