| Objectives To explore the significance and mechanism of PAF and ET-1 during acute gastric mocusa following traumatic brain injury(TBI) by observing the changes of serum platelet-activating factor (PAF) , plasma endothelin(ET)-1 level and the expression of ET-1 in gastric mucosa at different time phases after TBI in rat models.Methods 70 healthy adult Wistar rats were randomly divided into normal control group, sham-injuried group, and traumatic brain injury groups at hour 4,12,24,72 and at day 5 post-trauma(each group 10 rats), then made the models of traumatic brain injury. The serum level of PAF in each group were examined by ELISA methods and the level of ET-1 in plasma was examined by radioimmunoactive(RIA). The stomach of the rats were removed for observing condition of gastric mucosa and the expression of ET-1 on gastric mucosa in each group by immunohistochemistry(IHC). Results The serum level of PAF and ET-1 in normal control group and sham-injuried group was no significant on statistics difference; The level of PAF in serum increased from hour 4 post-trauma and reached a peak at hour 24, then drop to the normal level at day 5 after brain injury. The level of ET-1 in plasma significantly increased in injury groups compared with the normal control group and sham-injury group and showed a peak at the 12th hour post-injury (P<0.01), then begins to decrease thereafter the 12th hour, but remains a higher level than normal control group, which reaches normal level at day 5. In addition, UI increased dramatically at the 4th hour (P<0.01) and reach a maximum value at the 24th hour then reached normal level at the 5th day after brain injury. The expression of ET-1 was stained as brownish grains and localized in the cytoplasma of gastric epithelial cells, vascular endothelium cells, vascular smooth muscule cells and stomach smooth muscle cells, both the proportion and cellular intensity of ET-1 positive cells were significantly higher in traumatic brain injury group than in normal control group. The expression of ET-1 in sham-injuried group is the same with normal control group.Conclusion The results indicate that: The level of ET-1 in plasma and PAF in serum increased after traumatic brain injury, at the same time the expression of ET-1 on gastric mucosa were also enhanced. Furthmore the level of ET-1 in plasma related to with UI. Both ET-1 and PAF aggravated acute gastric mucosa lesion by decreasing blood flow, affecting microcirculation of gastric mucosa and increasing the vasopermeability, deteriorating the barrier of gastric mucosa respectively. Replenishment of ET-1 and PAF antagonist may relieve extent and incidence rate of AGML in early phase after brain injury. |
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