Cerebral Hemodynamic Changes Associated with Neuroinflammation under Seawater Immersion Hypothermia

Abstract Traumatic brain injury (TBI) combined with seawater immersion hypothermia (SIH) is one of the main causes of death and disability in shipwrecks. However, the impact of SIH on brain injury is still unclear. In this study, we used 8-week-old C57BL/6 mice to establish a controlled cortical impact model and simulate the hypothermia caused by seawater immersion after mice with TBI fell into seawater. The vital signs of the mouse model were continuously measured in the early stage of modeling, and the CBF of the mouse was recorded using laser scatter contrast imaging before and after modeling and after 6 and 24h. The cerebral cortex of 24h mice was collected for histopathological examination and enzyme-linked immunosorbent assay. The behavioral functions were assessed by behavioral analysis. The results showed that brain parenchymal injury was exacerbated during hypothermia in mice with TBI. CBF was significantly reduced in the hypothermic group compared with the normothermic group, and the levels of some inflammatory cytokines significantly increased and were correlated with low CBF. Overall, the results of this study suggested a correlation between inflammatory progression and low CBF, indicating that venous blood flow might be used for assessing neuroinflammatory progression after hypothermic trauma.