| OBJECTIVE : Treating by giving injection of DFX in rats with TBI via controlled cortical impact. Detecting the expression of HIF-1α, Ngb and VEGF in penumbra,and then further detecting the vascular regeneration,the neuronal apoptosis and the change of lesion volume in acute stage of TBI. In order to reveal the cerebral protective effect of DFX and its potential mechanisms in initiating the endogenous protective pathway after TBI in acute stage.METHODS : Ninety SD rats were randomly divided into three groups: sham operation group(n=30), experimental group(n=30) and control group(n=30). Rats in the experimental group and control group were respectively established a controlled cortical impact(CCI) model, and the sham rats underwent the same anesthesia surgical procedure, but were not injured. The rats in experimental group were intraperitoneal injected of DFX(100mg/kg) at 2h and 6h after injury, followed administered once every 12 h. Rats in the control group were administered with saline at the same time point. At 6h, 12 h, 24 h, 48 h after TBI,six rats in each group were sacrificed, and the brains were harvested. The expression of HIF-1α, Ngb and VEGF in cerebral penumbra was detected by RT-PCR and Western blot. The apoptosis of nerve cells was detected by TUNEL method. Six rats of each group underwent MRI examination at 3.0T 3d after TBI and the lesion volume was calculated on the basis of T2-weighted images. Then the brains were harvested and the microvessel density in penumbra of each group was detected by immunohistochemical staining method.RESULTS : The expression of HIF-1α m RNA in penumbra of the experimental group and the control group increased significantly in early stage after TBI, and both reached peaks at 12 h after injury(3.2 folds and 4.3 folds of the sham group respectively), then receded slowly, and maintained a fairly high level until 48 h after injury(2.2 folds and 3.4 folds of the sham group respectively). The expression of HIF-1α m RNA in the experimental group were significantly higher than those in the control group at 6h 12 h, 24 h, 48 h after injury(P﹤0.01). The expression of HIF-1α protein of the control group significantly increased in early stage after TBI, then gradually decreased after 6h after injury, and still significantly higher than those in the sham group until 48 h after injury(P﹤0.01). The expression of HIF-1α protein of the experimental group also increased significantly in early stage after TBI, and reached peak at 12 h after injury, and maintained a fairly high level until 48 h after injury. The expression of HIF-1α protein in the experimental group were higher than those in the control group at 12 h, 24 h, 48 h after injury(P﹤0.05).The expression of Ngb m RNA of the experimental group and the control group increased remarkably in early stage after TBI, and both reached peaks at 12 h after injury(2.6 folds and 3.3 folds of the sham group respectively), then receded slowly, maintained a fairly high level until 48 h after injury(1.7 folds and 2.6 folds of the sham group respectively). The expression of Ngb m RNA in the experimental group were higher than those in the control group at 12 h, 24 h, 48 h after injury(P﹤0.05). The expression of Ngb protein of the experimental group and the control group significantly increased in early stage after TBI. The control group reached peaks at 12 h and the experimental group reached peaks at 24 h after injury, and all maintained a fairly high level until 48 h after injury. The expression of Ngb protein in the experimental group were higher than those in the control group at 12 h, 24 h, 48 h after injury(P﹤0.05). The m RNA and protein expression of VEGF of the experimental group and the control group gradually increased in early stage after TBI, tended to be gentle at 24 h and 48 h after injury, but maintained a fairly high level. The m RNA and protein expression levels of VEGF in the experimental group were higher than those in the control group at 6h 12 h, 24 h, 48 h after injury(P<0.05). The apoptosis rate of neuron in the experimental group was less than that in the control group at 6h 12 h, 24 h, 48 h after injury detected by TUNEL(P<0.05). The microvessel density in the experimental group was higher than that in the control group at 3d after injury(P<0.05),and the lesion volume were smaller than that in the control group(P<0.05).CONCLUSIONS :(1) DFX can induce the gene and protein expression of HIF-1α, Ngb and VEGF after TBI in acute stage.(2) DFX can promote the vascular regeneration, inhibit the neuronal apoptosis and reduce the lesion volume, which shows that DFX has cerebral protective effect on TBI in acute stage.(3) The cerebral protective effect of DFX may be associated with the ability to induce the expression of HIF-1α which can further induce the expression of Ngb and VEGF, and then promote the vascular regeneration, inhibit the neuronal apoptosis. |
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