Contents lists available at ScienceDirect Legal Medicine journal homepage: www.elsevier.com/locate/legalmed Na + /K + -ATPase, acetylcholinesterase and glutathione S-transferase activities as new markers of postmortem interval in Swiss mice Caren A.R. da Fonseca a,b , Jaini Paltian a,b , Angélica S. dos Reis a , Cristiani F. Bortolatto a , Ethel A. Wilhelm a,b, ⁎ , Cristiane Luchese a, ⁎ a Programa de Pós-graduação em Bioquímica e Bioprospecção, Laboratório de Pesquisa em Farmacologia Bioquímica (LaFarBio), Grupo de Pesquisa em Neurobiotecnologia (GPN), Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas (UFPel), CEP 96010-900 Pelotas, RS, Brazil b Curso de Bacharelado em Química Forense, Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas (UFPel), CEP 96010-900 Pelotas, RS, Brazil ARTICLE INFO Keywords: Forensic markers Excised organs Enzymes Biological tissues Time of death ABSTRACT Determining precisely the postmortem interval (PMI) is a key parameter for forensic researches, given that various physical, biochemical and metabolic changes begin to occur in the body after death. In the present study, the Na + /K + -ATPase, glutathione S-transferase (GST) and acetylcholinesterase (AChE) activities were evaluated. For this, male adult Swiss mice were killed by isoflurane inhalation anesthesia and divided into four groups according to time of death (0, 6, 24 and 48 h). The brain, liver, kidney and skeletal muscle tissues were removed. Our results revealed that at the time of 6 h, there was a decrease on Na + /K + -ATPase and GST activities in the brain and liver tissues, respectively. In addition, at this time point, an increase on renal GST activity was verified. At the time of 24 h, an increase on the cerebral AChE and renal GST activities was observed, while the cerebral Na + /K + -ATPase activity was decreased. Forty-eight hours after death, cerebral Na + /K + -ATPase and renal GST activities remained decreased and increased, respectively. In addition, no alteration was observed on the GST activity in the skeletal muscle and brain (in PMIs evaluated). The present study revealed that the brain and kidney (at the times of 24 and 48 h) were the tissues that suffered the most changes in almost all the enzymes evaluated. Our results demonstrated that enzyme activity assessments are reliable, easy-to-perform and low-cost determinations, and could be promising postmortem markers. 1. Introduction Postmortem interval (PMI) is a key parameter for forensic re- searches [1]. In criminal cases, the precise determination of the PMI is essential to obtain information about the circumstances of death, for confirmation or invalidation of alibis, and finally, for the solution of a crime [2]. After death, physicochemical changes occur in the body immediately, and sequentially progresses until the body completely disintegrated. Endogenous and environmental factors strongly influ- ence these changes, such as temperature, humidity, subject age, medi- cation, disease, and decomposition stage, making difficult to precisely estimate the PMI [1]. Importantly, biochemical and metabolic changes in human body tissues are triggered by lacking of circulating oxygen, cellular degradation, enzymatic reactions, and interruption of anabolic meta- bolite production [3]. In fact, when the choice of markers is appro- priate, these changes can provide useful information about the death cause and PMI estimate [1]. In this context, the development of new approaches to find the biochemical and metabolic changes in tissues has been highlight, since they are not changed or contaminated quickly and easily. Combinations of conventional methods together with wit- nesses are useful to determine death time, given that erroneous results can be found when only one method is used [4]. In view of this, several methodologies have been described aiming at determination of PMI, including evaluate body cooling (nomogram method), potassium in vitreous humor, metabolic processes (supravital reactions), physicochemical processes (rigor mortis, lividity), as well as environmental factors such as bacterial processes (putrefaction) [5]. https://doi.org/10.1016/j.legalmed.2018.11.003 Received 31 May 2018; Received in revised form 12 October 2018; Accepted 2 November 2018 ⁎ Corresponding authors at: Programa de Pós-graduação em Bioquímica e Bioprospecção (PPGBBio), Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas (UFPel), Campus Capão do Leão, Pelotas CEP 96010-900, RS, Brasil (E.A. Wilhelm). Programa de Pós-graduação em Bioquímica e Bioprospecção (PPGBBio), Centro de Ciências Químicas, Farmacêuticas e de Alimentos, Universidade Federal de Pelotas (UFPel), Campus Capão do Leão, Pelotas CEP 96010-900, RS, Brasil (C. Luchese). E-mail address: ethelwilhelm@yahoo.com.br (E.A. Wilhelm), cristiane_luchese@yahoo.com.br (C. Luchese). Legal Medicine 36 (2019) 67–72 Available online 03 November 2018 1344-6223/ © 2018 Elsevier B.V. All rights reserved. T