| ?Background?Insulin is an endogenous hypoglycemic hormone,but excessive exogenous insulin can cause serious toxic side effects,such as convulsions,hypoglycemic coma,and even death.With the widespread use of insulin,there are more and more cases of accidental,suicide and even homicide caused by insulin overdose.So far,more than 100 cases of insulin homicide have been reported at home and abroad,but this is only the tip of the iceberg.Due to the lack of specific pathological changes in insulin overdose death and the difficulty of drug(toxic)analysis after death,it has been a scientific problem in international judicial expertise.Therefore,it is particularly important to study the half lethal dose of hypoglycemic encephalopathy caused by insulin overdose and to establish a rat model of hypoglycemic encephalopathy to observe its behavioral manifestations,histopathological characteristics and death mechanism.In clinic,insulin poisoning is mainly diagnosed according to the level of blood insulin and blood glucose,and the ratio of C-peptide to insulin(C ? I),but these results can not be used in forensic identification because of the influence of cadaveric chemistry.Due to the release of hemoglobin by autolysis of human red blood cells after death,insulin degrades rapidly and insulin in cadaveric blood is much lower than the actual level before death;glucose in postmortem blood is affected by glycolysis,glycogen decomposition,corruption and autolysis,etc.There was no correlation between blood glucose and the actual level before death.Therefore,unless the serum of the deceased is retained or dissected quickly after death,it is difficult to carry out forensic identification of insulin poisoning death by detecting the levels of insulin,blood glucose and C-peptide in the blood of corpses.Hypoglycemia encephalopathy(HE)has been recognized as the main mechanism of death caused by insulin poisoning.Glucose is the most important energy in the brain.When blood sugar is less than 2.0 mmol/L,the concentration of glucose in the brain is close to zero.Consciousness and coma occur.If the time of coma exceeds 30 minutes,irreversible damage to the central nervous system(CNS)will occur.Therefore,based on the above theoretical basis,we infer that the determination of half lethal dose of insulin-induced hypoglycemic encephalopathy and the establishment of hypoglycemic encephalopathy model in rats play an important role in subsequent experiments.In this experiment,we first observed the effect of insulin excess on the behavior of mice by studying acute insulin poisoning in mice,and calculated the half lethal dose of acute insulin poisoning in rats by measuring the half lethal dose of acute hypoglycemic encephalopathy in mice.Then,we established a rat model of hypoglycemic encephalopathy induced by excess insulin according to Acta Neuropathold method to complete the follow-up histopathology.Research.In order to fully reveal the mechanism of selective damage of hippocampal neurons in hypoglycemic encephalopathy induced by insulin overdose,screen out molecular markers of diagnostic value for forensic pathological diagnosis,and provide scientific basis for forensic diagnosis of death caused by insulin poisoning.?Objectives?In this study,we established a rat model of acute hypoglycemic encephalopathy induced by insulin overdose,reviewed the relevant literature,screened differential proteins related to cardiotoxicity of AMI poisoning,and preliminarily explored the mechanism of central nervous system damage caused by hypoglycemic encephalopathy poisoning induced by insulin overdose in mice.(1)To establish an acute toxic model of hypoglycemic encephalopathy in mice,and observe the effects of acute insulin overdose on the behavior of mice and the morphological changes of multiple organs in mice.(2)The LD50 of mice with hypoglycemic encephalopathy was determined.(3)Calculate the half lethal dose of insulin poisoning in rats and normal persons;(4)To reveal the mechanism of selective damage of hippocampal neurons in hypoglycemic encephalopathy induced by insulin overdose.?Materials and Methods?(1)half lethal dose(LD50)of acute insulin poisoning in mice was determined:Sixty Kunming(KM)mice were randomly divided into 6 groups with 10 mice in each group,half male and half female.Then the experimental KM mice were further divided into5 doses of insulin acute exposure group and sham operation control group.The acute exposure group was injected intraperitoneally with insulin solution of 0.7 IU/kg,1.9 IU/kg,4.9 IU/kg,13.0 IU/kg and 34.5 IU/kg,respectively.The mice in the control group were injected intraperitoneally with single saline 0.1ml.To observe the behavioral changes and survival rate of acute insulin poisoning in mice.Based on the mortality data of 10 mice in each of the above 5 groups,the LD50;of acute insulin poisoning by intraperitoneal injection of insulin in mice was calculated by Sun's modified Kirschner's method(point slope method)and Bliss method.(2)to observe the behavior of mice after acute insulin poisoning;(3)to establish the model of hypoglycemic brain injury induced by insulin overdose in rats: Fifty-five adult male SD(Sprague Dawley)rats were randomly divided into acute hypoglycemia group(n = 9),resuscitation group(n = 9)and blank control group(n = 9).According to the method recommended by Auer et al in Acta Neuropathold in the early stage,the rat model of hypoglycemic brain injury induced by insulin overdose was established,and the follow-up neuropathological study was completed.(4)to investigate the pathological characteristics of insulin poisoning brain in rats.?Results?(1)by intraperitoneal injection of insulin at a single dose of 0.7 IU/kg,1.9 IU/kg,4.9 IU/kg,13.0 IU/kg and 34.5 IU/kg,the LD50 of mice was calculated to be 10.481IU/kg,LD95 and 99.75 IU/kg;.(2)the behavior of mice with acute insulin poisoning could be observed by intraperitoneal injection of insulin at a single injection of 0.7 IU/kg,1.9 IU/kg,4.9 IU/kg,13.0 IU/kg and34.5 IU/kg.The rapid occurrence of hindlimb weakness,intermittent convulsion and contralateral convulsion of angular arch after exposure can be regarded as the successful manifestation of exposure.(3)the model of hypoglycemic brain injury induced by insulin overdose was established.through the neuropathological study of hypoglycemic brain injury,it was found that hippocampal injury was a characteristic pathological change of insulin overdose,which laid a foundation for the follow-up study of hypoglycemic encephalopathy.?Conclusion?(1)Acute insulin poisoning model in mice can be established by intraperitoneal injection of 1.0 IU/m L insulin saline solution.The rapid onset of hind limb weakness,intermittent convulsions and angular arch reflex convulsions after poisoning can be regarded as the successful manifestations of poisoning.(2)LD50 of mice was calculated to be 10.481 IU/kg by intraperitoneal injection of 1.0IU/m L insulin saline solution.(3)According to the results of LD50 in mice and literature,the LD50 in rats was calculated and verified mutually,and the value was within the effective range.(4)Histopathological knowledge showed that hippocampal injury was a characteristic pathological change of insulin overdose,which laid a foundation for the follow-up study of hypoglycemic encephalopathy. |
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