Effect Of Restrain Stress On Crush-induced Damage Of Lung, Liver And Kidney Tissue In Rats

Objective: In clinical practice and forensic practice, the death caused by thenonfatal mechanical damage has been increasing. The kind of injury ofternhappens in the soft tissue contusion, bounding limb for a long time, such astraffic accident, earthquake, and turtore. This kind of injury itself is notenough serious to leading to death, so the causes of death often becomeintangible or controversial, which brings about a pernicious influence onsociety. Therefore, the scientific problem urgently to be solved is revealingexact death mechanisms of nonfatal mechanical damages in critical caremedicine and forensic medicine.The effects of nonfatal mechanical damage on the organism include: thefirst, the impact of the damage itself to the organism, including local tissueinjury and the distant organ damages and systemic inflammation response et al;the second, the stress response induced by tissue injury as physical stressor;the third, the stress response induced by the negative emotion arised frompsychological and social factors. The hypothalamic-pituitary-adrenal (HPA)axis and the locus ceruleus norepinephrine axis (LC/NE) are twoneuroendocrine systems, which respectively stimulates the secretion of CAand cortisol into the blood stream, play major role in stress. Although themodest neuroendocrine response can protect organism against injury, theexcessive neuroendocrine response will lead to functional disorder andmetabolism disturbance. The results of histopathology and ultrastructureexamination have been the major basis by which forensic pathologistsdiagnose disease and determine cause of death. Whether the combined effectof nonfatal mechanical damage and stress will cause the significant changes inhistopathology and ultrastructure remain unclear. The crush injury model was recognized commonly as the animal modelto copy the soft tissue contusions; restraint stress model was recognized asanimal model to copy the psychological stress. To explore the effect of injuryand stress on the histopathology and ultrastructure of major organs, the presentstudy will set up the compound model of restraint stress and crush injury, andexamine the histopathology and ultrastructure of lung, liver and kidney. Thestudy results will provide the strategies for cure and the theoretical foundationfor the determination of cause of death in the case involving nonfatalmechanical damage and stress.Methods: Seven-two male Sprague-Dawley rats were divided into fourgroups randomly.â‘ Control group: the rats are fasted and water deprivatedat a defined time period every day (8h), keeping7consecutive days;â‘¡Restrain stress group: the rats are restrained8h at a defined time period everyday, fasting and water deprivating simultaneously, keeping7consecutive days;â‘¢Crush group: the hindlimbs of rats were compressed with24kg standardheavy object for6h;â‘£Restrain stress and crush group: the rats are restrained8h at a defined time period every day, keeping7consecutive days, at8thdaythe hindlimbs of rats were compressed with24kg standard heavy object for6h.The rats of groupâ‘ and groupâ‘¡were executed at the end of model; therats of groupâ‘¢and groupâ‘£were executed respectively at0d,1d,3d,5dand7d after compress. The lung, liver and kidney of every group rats wereseparated, fixed, and observed by LM and TEM.Results:1. The pathomorphological changes in the lung, liver and kidney1.1The pathomorphological changes in the lungThere was no obvious pathological change in control group. A fewinflammatory cells infiltration and the mild widened alveolar septa wereobserved in restrain stress group. In crush group, The pathomorphologicalchanges became more significant along with time prolonged. A fewinflammatory cells infiltration and the mild widened alveolar septa wereobserved at0d after crush, and then decrease in the size of alveolar, bullae of lung, emphysema and pneumorrhagia were observed orderly at1d,3d,5d and7d after crush. But the pathological changes in restraint stress+crush injurygroup became the most serious among all groups.1.2The pathomorphological changes in the liverNo obvious pathological change was observed in control group. HEstains showed that swollen hepatocytes in restrain stress group. In crush group,hepatic cords malalinement was showed at0d. Along with time prolonged, themore significant pathological changes such as some inflammatory cellsinfiltration, hepatic sinusoid hypertrophy and hyperemia were observed at1d,3d,5d and7d in crush group. But the most serious pathological changes wereshowed in restraint stress+crush injury group.1.3The pathomorphological changes in the kidneyHE stains showed that clear tissue structure in the control group. A few ofinflammatory cells infiltration and anarrowed renal capsule were observed inrestraint stress group; In crush injury group, swelling, congestive and distortedglomeruli were showed, and became more serious along with time prolonged.The renal tubules epithelial cells swelling and cells in the lumens cilia on thesurface of nephric canaliculus ruptured were observed in restraint stress+crushinjury group, and became more aggravated along with time expanded.2. The ultrastructure changes in the lung, liver and kieney.2.1The ultrastructure changes in the lungThe fused or swollen locally respiratory membrane (arrow), disappearedmicrovillus partly in alveolar type II epithelial cell (arrow) were showed inrestraint stress group. Similar changes were also observed in crush injurygroup. In restraint stress+crush injury group, beside above changes, a large ofvacuoles in the cytoplasm were observed in alveolar type II epithelial cell.2.2The ultrastructure changes in the liverIn both restraint stress group and crush injury group, increased glycogengranules (arrow) and fused mitochondria membrane (arrow) were observed.Beside above changes, chromatin marginatin (arrow) was also showed inrestraint stress+crush injury group. 2.3The ultrastructure changes in the kidneyIn restraint stress, fused mitochondria membrane (arrow) was showed.The more serious changes including widened nuclear-week gap (arrow) andenlarged ER were observed in crush injury group. Beside above changes, thepyknotic nuclei and chromatin marginatin (arrow) were also displayed inrestraint stress+crush injury group.Conclusions: The present study set up the compound model of restraint stressand crush injury successfully and observed histopathologic and ultrastructurechanges in lung, liver and kidney of rats`.The conclusions were as followed:(1) Both restraint stress and crush injury respectively cause significantpathological damages and ultrastructure changes in lung, liver and kidney ofrats.(2) Compared with crush injury or restraint stress, the combined effect ofrestraint stress and crush injury will cause the significant change inhistopathology and ultrastructure of above organs.