Abstract: Objective To investigate the expression of Endothelial Lipase (EL) in rat brains after being injuried. Methods Forty healthy adult SD rats were used, thirty one rats were successfully prepared as traumatic brain injury (TBI) model. The expression of EL was tested by Western blotting at various time points after injury. Double immunofluorescent staining was used to observe the cell distribution of EL as well as changes in expression levels after injury. Results Western blotting data showed that EL proteins in lesion site increased gradually and reached a peak on the 3rd day post injury, and it decreased to the lowest level until 2 weeks after the injury. EL was localized in neurons as shown by co-localization with neuronal nuclei (NeuN). Intensity of immunofluorescence was weak in intact brain but greatly enhanced on the 3rd day after the injury. In addition, temporal expression pattern of Caspase-3, a key protein involved in apoptosis, was similar to that of EL, and expression of Bcl-2, which is involved in anti-apoptosis was also temporally regulated. Conclusion The brain injury results in up-regulation of EL expression in traumatic brain sites suggesting that it may participate in brain injury-induced apoptosis as well as neuronal regeneration processes.

Key words: Traumatic brain injury, Lipid metabolism, Endothelial lipase, Western blotting, Immunofluorescence, Rat