Changes of cerebral mitochondrial respiratory function and ultrastructure after traumatic brain injury in response to hypothermia / 中华创伤杂志

ABSTRACT

Objective To study the effect of hypothermia on cerebral mitochondrial respiratory function and ultrastructure after traumatic brain injury(TBI). Methods Sprague-Dawley rats were subjected to moderate brain injury by using lateral fluid-percussion(LFP)and randomly divided into sham operation group,normothermic TBI group(rectal temperature for 36-37℃)and hypothermic TBI group(rectal temperature for 31-32℃ lasting for two hours).The ipsilateral brains were dissected and homogenized brain tissues were extracted to obtain mitochondfia by density-centrifugation and speed-centrifugation at 2,24 hours and at days 3 and 7 after TBI.The mitochondrial uhrastructure was studied by electron microscope.The indices of respiratory control rate(RCR)and P/O ratio of mitochondrial respiratory function were measured after oxygen consumption was determined with a Clark-type electrode.Results The mitochondrial uhrastructure of normothermic TBI group was damaged severely while that of hypothermic TBI group kept relatively integrated.The RCR and P/O ratio were markedly decreased two hours after TBI and reached the lowest level at the 24th hour(P＜0.01).At day 7,RCR kept at a lower level compared with sham operation group but P/O ratio recovered to normal.Change of RCR was similar in hypothermie TBI group and normothermic TBI group.However,RCR of the hypothermic TBI group was significantly higher than that of the normothermic TBI group within three days after TBI.In the meantime,P/O ratio recovered to normal three days after TBI. Conclusion Hypothermia can improve cerebral mitochondrial respiratory function and protect the mitochondrial structure after TBI.