ABSTRACT
Objective To study the dynamic expression and distribution of high mobility group box 1 (HMGB-1)in diffuse axonal injury (DAI)in rats and to clarify its involvement in the inflammatory reaction after DAI in rats,in order to provide new targets for the clinical treatment of DAI.Methods A DAI model was established using a coronal rotation device and evaluated by HE,Glees-Marsland silver staining,and Mallory phosphotungstic acid hematoxylin staining.Immunohistochemistry,Western blot and RT-PCR were used to detect the expression and distribution of HMGB-1 in the cortex of DAI rats at 6 h,1 d,3 d and 7 d.And TUNEL was used to examine the apoptosis of neurons in DAI rats.Results Immunohistochemical results showed that at 6 h and 1 d after DAI,the number of HMGB-1-positive cells decreased,but at 3 and 7 d it began to increase.Western blot also showed that during the early stage after DAI (6 h and 1 d),the level of HMGB-1 protein in the cortex was significantly lower than that in the control group,but at the late stage (3 and 7 d)after DAI it significantly increased compared with that in the control group until 7 d.RT-PCR showed that at 6 h after DAI there was no significant increase in the level of HMGB-1mRNA,but at 1 d there was a slight increase compared with the control group;at 3 and 7 d,it showed an obvious significance.TUNEL staining indicated that the significant neuronal apoptosis appeared as early as 6 h after DAI,and reached the peak at 3 d;it started to decrease at 7 d but still remained at a relatively high level.Conclusion The dynamic expression and distribution of HMGB-1 showed significant changes with the time course after DAI in rats.They decreased at the early stage but increased at the late stage.At the early stage, HMGB-1 is mainly passively released by the necrotic neurons,and at the late stage it may be actively secreted by the active inflammatory cells.HMGB-1 may mediate the post-DAI neural cell apoptosis by inducing the inflammatory reaction.
ABSTRACT
Objective To study the effect of extracellular signal-regulated kinase1/2 (ERK1/2)inhibitor U0126 on matrix metalloproteinase-9(MMP-9)in brain tissue after subarachnoid hemorrhage(SAH)in rats and to investigate the action mechanisms of ERK1/2 and M M P-9 in blood-brain barrier(BBB)injury and brain edema after SAH.Methods Seventy-two male Sprague-Dawley rats were randomly divided into four groups:SAH model,sham operation,U0126 intervention,and vehicle groups.A SAH model was induced by injection of autologous blood into cisterna magna once.The dry-wet weight method was used to detected brain tissue water content in order to evaluate cerebral edema.BBB permeability was evaluated by the Evans blue extravasation method.The immunohistochemical method was used to detect the expression of MMP-9 and phosphorylated ERK1/2.Results The expression of phosphorylated ERK1/2 and MMP-9 was lower in the sham operation group.The expression of both was up regulated at 24 hours after SAH.The brain water content and Evans blue content also increased.U0126 treatment decreased the phosphorylation of ERK1/2 and the expression of MMP-9,improved the BBB permeability,and alleviated brain edema.Conclusions MMP-9 is involved in the pathophysiological processes of early BBB injury and brain edema aft er SAH.ERK1/2 pathway may play a vital role in the expression of MMP-9.U0126 may protect BBB and reduce brain edema after SAH by inhibiting the phosphorylation of ERK1/2.