Study On Expression And Postmortem Stability Of HSP70 In Hippocampus Of Hemorrhagic Shock Rat

Background and objective: Hemorrhagic shock death is one common cause of death in traffic accident,medical malpractice and criminal case. The most of present studies on hemorrhagic shock were focus on fluid replacement and ischemia-reperfusion injury, and there were few reports about the estimation of survival interval in hemorrhagic shock death. The estimation of survival interval after hemorrhagic shock remains to be a complicate problem in forensic medicine and no standard was satisfied. Heat shock protein 70 (HSP70) was one kind of HSPs expressed by heat shock gene which induced by many stresses such as ischemia,hypoxia,trauma and infection, it was expressed in many kinds of cells and presented a certain time regularity. In this study we will investigate the expression and postmortem stability of HSP70 in hippocampus of hemorrhagic shock rat, and discuss its forensic medical significance.Methods:⑴Material:One hundred and five healthy SD rats (from Chongqing Medical University Experimental Animal Center) were divided into normal group,sham-operation group,hemorrhagic shock group,traumatic control group and postmortem stability group randomly. In hemorrhagic group and postmortem stability group, rats were submitted by controlled bleeding, according to the improved Wigger method. And the model of local moderate brain contusion in traumatic control group was established by the free-falling-body impact device according to the Feeney method.⑵The sample of hippocampus were harvested at different time points after hemorrhagic shock or trauma.⑶The hippocampus tissue of paraffin wax slices were prepared for HE staining and microscope observation.⑷The expression of HSP70 at different time were detected by immunohistochemical technique.⑸The results were analyzed by SPSS 10.0 software.Results: 1 hour after hemorrhagic shock, expression of HSP70 protein in hippocampus and vessel wall cells can be detected, after that, the expression intensity increased gradually and strong expression can be detected 2 hours later (P<0.01). In traumatic control group, expression of HSP70 protein can be detected in vessel wall cells and red blood cells only, weak expression of it can be detected in hippocampus. The expression of HSP70 in postmortem group was similar with hemorrhagic shock 2 hours group(P>0.05).Conclusions: After hemorrhagic shock, the expression of HSP70 in hippocampus altered regularly. The expression of HSP70 protein increased 1 hour after shock, then reached to a peak at 2 hours after injury, and showed nice postmortem stability under the environment of -20℃degree. The level of HSP70 protein can be used as a referenced index to estimate the survival interval after hemorrhagic shock.