Preliminary study on the rewarming strategies in mice with traumatic brain injury combined with seawater-immersed hypothermia

YE Dan; LIN Long; HOU Pengwei; ZHANG Hao; WEI Liangfeng; WANG Shousen

Abstract：Objective By constructing a mouse model of traumatic brain injury combined with seawater-immersed hypothermia(TB1-S1H),to observe the effect of rewarming duration on the recovery of injury in model mice and to assess the therapeutic efficacy of rewarming with electric heating pads.Methods Forty-eight male C57BL/6 mice were randomly divided into 4 groups:the control group,the model group,the electric heating pad rewarming group(with the core body temperature of the mice rising to(37×1)℃ as the end of rewarming mark)and the electric heating pad rewarming extension group(after the mice reached the normal body temperature,they continued to be rewarmed for 1 h by using the electric heating pad),12 mice in each group.Vital signs of mice were observed throughout the whole process,and the mortality rate of mice in each group was counted separately.HE staining and Nissl staining were observed to assess the degree of neurological damage and the number of neuronal loss in each group,and the water content of the brain was measured and stained with Evans blue after 24 h.The mortality rate of the model group was higher than that of the rewarmed mice.Results The mortality rate of mice in the model group was higher than that of mice in the rewarming group(P＜0.05),and the mortality rate of mice in the rewarming group with electric heating pads and mice in the prolonged rewarming group with electric heating pads were comparable with no statistical difference.After HE staining and Nissl staining in each group,it was found that the histopathological changes in the brain of mice were closely related to whether or not the mice were rewarmed.Compared with the model group,the brain tissue damage of mice in the rewarming group was significantly improved,and neuronal loss was reduced(P＜0.05).In addition,the proportion of damaged neurons in the mice in the electric heating pad rewarming group was less than that in the electric heating pad rewarming prolonged group(P＜0.05).Compared with the control group,the water content of brain tissue and Evans blue exudation of mice in the model group were significantly increased,and the differences were statistically significant(P＜0.05).Cerebral oedema was significantly reduced after rewarming of the electric heating pad,and Evans blue exudation decreased(P＜0.05).However,prolonged rewarming resulted in increased Evans blue exudation(P＜0.05).Conclusion Rewarming improves the degree of brain tissue injury and its prognosis in TBI-SIH mice,and prolonged rewarming time was not significant for the recovery of neurological injury.