Atividade da acetilcolinesterase em córtex cerebral e músculo gastrocnêmio como biomarcador do intervalo pós-morte: um estudo experimental em ratos Wistar machos e fêmeas de diferentes idades

Abstract

The postmortem interval (PMI) can be defined as the time that elapses between the death of an individual up to the moment that the corpse is found. The most commonly used certified methods for estimating PMI are based on the observation of cadaveric phenomena that occurs immediately after death. However, these methodologies have divergences in their results that can reach eight hours of difference, due to extrinsic and intrinsic interferences. Thus, there has been an increasing search for biochemical markers that can support more accurately the PMI estimation. In this sense, the activity of the enzyme acetylcholinesterase (AChE), found in the brain and muscle, could be studied as a possible biochemical marker of PMI. Thereby, the aim of this study was to evaluate the activity of AChE in the cerebral cortex and gastrocnemius muscle of female and male rats of different ages submitted to an experimental protocol of PMI. Wistar rats were divided into females and males (young, adult, old) according to postmortem hours (hpm): Group I - 0hpm; Group II - 6hpm; Group III - 12hpm; Group IV- 24hpm; Group V- 48hpm. The animals were euthanized and kept in a temperature-controlled environment until the postmortem time stipulated for each group was over. After that, the cerebral cortex and gastrocnemius muscle were collected to evaluate the activity of AChE. The results demonstrated differences in AChE activity in relation to PMI, gender and age. In females, enzymatic activity AChE in the cerebral cortex of the young group of 12hpm and in the adults of 24hpm. On the other hand, in males, a decline in the enzymatic activity of adults and elderly was observed from 6 to 48hpm, when compared to 0hpm. In the gastrocnemius muscle, females showed a reduction in enzymatic activity in the young group after 24hpm, however, in males a decline in AChE activity was observed in young group from 12hpm. There weren‘t any differences observed in the muscle of adult and old groups of both sexes. The results suggest that the activity of AChE might be a promising marker for PMI estimation, in addition of being able to provide information about the stages of decomposition related to sex and age. The methodology for AchE activity determination is quickly done, easy to handle, represents a low-cost investment and could be associated with other already existing methods of PMI estimation.