| Objective To establish rabbit brain blast injury model which is closed to actual situation, simple operation, quality standardization, high stability and good repeatability by using explosion shock wave combined with scrap iron pieces and observe traumatic condition changes of the rabbits in the first stage of the experiments.In the second and third stages of the experiments, the regulation function about the vagus nerve electrical stimulation to brain tissue pathology and edema, the degrees of systemic inflammatory response in brain and whole body and dysfunction of the autonomic nervous system will be observed and investigated in rabbit brain blast injury model established by using the method of the first stage of the experiments.Methods In the first stage of the experiments,24New Zealand white rabbits were randomly divided into four groups,4rabbites for preliminary experimental group,4rabbites for blank control group,6rabbits for control group,10rabbits for blast injury group. Explode the parietal cortex of the rabbit right brain which were craniotomy operation by using the self-design explosive devices. The vital signs, the brain CT and the brain tissue pathology were observed and recorded. Establish proper animal model makes the experiments into the phase2and3through studying quality control, high stability and repeatability of the simple rabbit brain blast injury model. In the second stage of the experiment,24New Zealand white male rabbits were randomly divided into three groups, control group(6), blast injury group(10), vagus nerve stimulation group(8). Built the rabbit brain blast injury model for blast injury group and vagus nerve stimulation group, while the right cervical vagus nerve of the rabbits in vagus nerve stimulation group was stimulated (10V,5HZ,5ms,20min) after blast brain injury. The changes of serum(6h after injury) and brain tissue (24h after wound) TNF-a, IL-1βand IL-10, the water contention and the pathological changes in brain tissue (24h after wound) were observed and recorded. In the third stage of the experiments,32male New Zealand White rabbits were divided into Sham-operated Group (n=8), blast injury group (n=12) and vagus nerve stimulation group (n=12)by random number table, in which blast injury group and vagus nerve stimulation group were based on brain explosive injury models. Vagus nerve stimulation group received right side cervical vagus nerve stimulation (10V,5HZ,5ms,20min) after brain blast injury. Each group of rabbit the TNF-a and IL-10in serum (8h and24h after injury) and cerebrospinal fluid (24h after injury), the water content in brain tissues were detected and the2h long distance ECG (electrocardiograms) before injury,6h～8h and22h-24h after injury concentrations were recorded in each group.Results Cerebral contusion, intracerebral hematoma, subarachnoid hemorrhage, intracranial pneumatosis and scrap iron residue standing for open craniocerebral injury were observed on the brain CT, while neuron degeneration necrosis, brain edema, hemorrhage and other pathological changes were appeared in the brain tissue pathology in the blast injury group. The level of serum and brain tissue TNF-a, IL-1βand the water contention in brain tissue were significantly higher than the control group and the vagus nerve stimulation group (P<0.01), while the level of IL-10was between the control group and the vagus nerve stimulation group (P<0.05) at the acute stage of brain explosive injury (6h～8h after injury). The level of serum and brain tissue TNF-aand the water contention in brain tissue were significantly higher than the control group and the vagus nerve stimulation group (P<0.05), the level of IL-10was significantly lower than that two groups (P<0.05), while the level of IL-10between the control group and the vagus nerve stimulation group was not significant (P>0.10) in the later stage of brain explosive injury (24h after injury). Compared with the Sham-operated group, the low frequency/high frequency (LF/HF) ratio, which reflects autonomic nervous system balancing indicators in the blast group and vagus nerve stimulation group was significantly higher (P<0.01) at the acute stage of brain explosive injury. The blast group LF/HF ratios decreased significantly (P=0.01) and vagus nerve stimulation group no significant changes (P=0.320) in later stage of brain blast injury.Conclusion The animal model on blast and shrapnel related traumatic brain injury in rabbits accords with imaging and pathological features of the craniocerebral blast injury models, is easily and standardly controlled, which can apply in the basic research of craniocerebral blast injury. The vagus nerve electrical stimulation can reduce brain edema degree, the levels of serum and brain tissue TNF-aand IL-1β, while increase the levels of serum and brain tissue IL-10in rabbits, which plays a key role in brain protection effect after brain blast injury in rabbits through ameliorateing the degree of systemic inflammatory response in brain and whole body. The vagus nerve electrical stimulation can improve and regulate the balance of the autonomic nervous system function, regulate respiratory and cardiovascular system function, which plays a key role in good prognosis after brain blast injury in rabbits. |
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