AIM: To explore the dynamic changes in the pressure of the lateral ventricle during acute brainstem hemorrhage and the changes of neural discharge of vagus nerve under the load of intracranial hypertension, so as to analyze their effects on the congestive degree of intestinal mucous membrane and the morphologic changes of intestinal mucous membrane.METHODS: An operation was made to open the skull to obtain an acute brainstem hemorrhage animal model.Microcirculatory microscope photography device and video recording system were used to determine the changes continuously in the caliber of jejunal mesenteric artery during brainstem hemorrhage and the changes with time in the congestion of jejunal mucosal villi. We used HE stain morphology to analyze the changes of duodenal mucosal villi. A recording electrode was used to calculate and measure the electric discharge activities of cervical vagus nerve.RESULTS: (1) We observed that the pressure of lateral cerebral ventricle increased transiently during acute brainstem hemorrhage; (2) The caliber of the jejunal mesenteric artery increased during brainstem hemorrhage.Analysis of red color coordinate values indicated transient increase in the congestion of jejunal mucous membrane during acute brainstem hemorrhage; (3) Through the analysis of the pathologic slice, we found enlarged blood vessels, stagnant blood, and transudatory red blood cells in the duodenal submucous layer; (4) Electric discharge of vagus nerve increased and sporadic hemorrhage spots occurred in duodenal mucous and submucous layer, when the lateral ventricle was under pressure.CONCLUSION: Brainstem hemorrhage could causeintracranial hypertension, which would increase the neural discharge of vagus nerve and cause the transient congestion of jejunal mucous membrane. It could cause hyperemia and diffused hemorrhage in the duodenal submucous layer 48 h after brainstem hemorrhage.