A Study On The Changes Of Energy Elements In The Liver Of Rats And Relationship With The Time Of Death

Background and purposeThe research of estimation of postmortem interval began in 1800 (Nysten).Since many factors effect on the changes of death, a single index never estimatepostmortem intervals. Over the centuries, many scholars have carried oncontinuous exploration, but till now they can still not accurately estimate thetime of death. There are only a few researches on using supravital reaction toestimate postmortem interval. Most are limited to the description ofmorphology and mechanical excitability. However, the research on the energyand material changes in liver is particularly prevalent in the sports medicine andorgan transplant. There is only a little outcome can be directly used in theforensic medicine. Therefore, we have designed the following experiment.We study the subject on the base of the predecessors the experiment willexplore effective ways to estimate postmortem interval by establishing differentanimal death models, using methods of combining macro-observation andmicro-analysis, and from the perspective of changes of glycolysis andadenosine neucleotides in liver after death, in order to providing availableinformation in the practice of Forensic Medicine.Materials and MethodsDivide 180 healthy Sprague-Dawley rats, weighing 250±20 grams weredivided into the group of neck broken, the asphyxiated and the group ofbleeding shock death. Respectively,The liver in the death point of 0min, 30min,1h, 1.5h, 2h, 3h, 4h, 6h, 8h, 12h, 18h, 24h were taken and fixed in the -20℃infridge. Every sample were divided into two parts, one sample was done byPAS (Periodic acid schiff) stained slides and PFK-2 (phosphofructokinase-2) immunohistochemistry staining, another was done by HPLC (high-performanceliquid chromatographic)to do quantitative measurements of ATP, ADP and AMP.At each time point choose the average of five animals as the test results. To dealwith the tissue by the following aspects:1. The slides of liver were stained by PAS and the stained slides weredoing computer image analysis, using gray changes to estimate the changes ofglycogen in the liver after death and accordingly estimate the time and causes ofdeath.2. PFK—2 immunohistochemistry staining to analyse and computer imageto observe the expression and regular changes in rat's liver.3. Use HPLC to do quantitative measurements of ATP, ADP and AMP inrat's liver.Results1. The glycogen content of the rats' liver presents linear decrease indifferent death time. It is inferred this can be regarded as a reference forestimation of postmortem interval.2. The PFK—2 immunohistochemistry staining of the rat's liver in the grayhave linear decrease with various times of death. It is inferred this can beregarded as a reference for estimation of postmortem interval.3. The content of ATP, ADP and AMP in the rat's liver presents regularchanges. What's more, with different causes of death their content within rat'sliver is different. It is inferred that this can be used to estimate the death timeand generally infer the cause of death, the changes of ATP content haveappliance value among the changes of ATP, ADP and AMP content in the rat'sliver.The content of ATP,ADP and AMP in rats' liver can be regarded as a referencefor estimation of postmortem interval. The content of ATP, ADP and AMP in rats' liver with different cause of death have statistic significance.The content of ATP, ADP and AMP in rat liver presents linear decreasewith the time of death, except the content of ATP in bleeding shock and thecontent of ADP, AMP in asphyxiate. Within-group comparison andbetween-group comparison have statistic significance.