The effects of mild hypothermia on expression of β - secretase after traumatic brain injury in rats

Objective To investigate the effects of mild hypothermia treatment on the expression of β - secretase (BACE) after traumatic brain injury (TBI) in rat model.Methods Adult male Sprague -Dawley rats were randomly divided into three groups:sham - operated group,TBI with normothermia group (37℃),and TBI with hypothermia group (32℃).The traumatic brain injury rat model was established with a fluid percussion device. Mild hypothermia intervention for 6 h immediately initiated after TBI in hypothermia group.At 24 h after TBI,rats were sacrificed and the brain hippocampus tissues were prepared for hematoxylin and eosin staining. The immunohistochemistry and immunofluorescence were used for the location of BACE.Gene transcription and protein expression of BACE were examined by reverse transcription -polymerase chain reaction (RT- PCR ) and Western blotting,respectively. Results Normothermia group showed increased BACE higher than that of sham - operated group ( P ＜ 0.05 ). However,hypothermia group showed significantly lower expression of BACE compared with normothermia group ( P ＜ 0.05), which showed no significant difference compared to the sham - operated group.Conclusions Mild hypothermia treatment,which plays a neuroprotective role,might decrease the level of BACE induced by traumatic brain injury,resulting in secondary brain injury. Key words: Traumatic brain injury;  Mild hypothermia;  β - secretase