A pre-injury high ethanol intake in rats promotes brain edema following traumatic brain injury

Drinking is a risk factor for traumatic brain injury (TBI), and ethanol can aggravate the outcome by promoting brain edema. The mechanism involved is not fully understood. It has been confirmed that aquaporin-4 (AQP4) and vascular endothelial growth factor (VEGF) play pivotal roles in cytotoxic/vasogenic brain edema individually, and both of these proteins are downstream regulatory factors of hypoxiainducible factor-1 alpha (HIF-1 alpha). In this study, we used a fluid percussion injury (FPI) model in rats to determine the effects of acute ethanol intake on the expression levels of HIF-1 alpha, AQP4, and VEGF prior to FPI. The animals were sacrificed 1, 2, 3, and 4 days post-injury. We found that the expression levels of HIF-1 alpha and AQP4 were significantly upregulated in the ethanol-pretreated groups, whereas the VEGF expression level was not. In addition, there was a positive correlation between HIF-1 alpha and AQP4. The results of this study indicate that cytotoxic brain edema may play an important role in the early stage of FPI in ethanol-pre-treated animals and that HIF-1 alpha and AQP4 might be involved.