title: Tau hyperphosphorylation is associated with memory impairment after exposure to 1.5% isoflurane without temperature maintenance in rats.
abstract: OBJECTIVE
  There is increasing interest in studying the role of tau hyperphosphorylation associated with memory impairment. We examined the involvement of tau hyperphosphorylation in memory impairment after hypothermia following isoflurane anaesthesia in rats.
  
  
  METHODS
  Adult rats were randomly divided into three groups: the control group received no treatment and others were subjected to 1.5% isoflurane anaesthesia with or without temperature control for 2 h. On the day before anaesthesia and on postanaesthetic days 1, 3 and 7, cognitive functions were assessed in a Y-maze test paradigm. To find the relationship between memory results and tau, we measured the site-specific phosphorylation of tau at Thr-205 and Ser-396 and the activity of protein phosphatase 2A within the hippocampus.
  
  
  RESULTS
  The spatial learning and memory of animals with hypothermia were impaired at day 1 after anaesthesia, compared with nonanaesthetized rats. Anaesthesia and hypothermia led to tau hyperphosphorylation at the Thr-205 and Ser-396 epitopes in the hippocampus. There was no significant difference in the protein phosphatase 2A activity between the control and the postanaesthetic rat hippocampal samples, whereas nearly 45% protein phosphatase 2A inhibition was detected in the anaesthetized without temperature maintenance rat samples.
  
  
  CONCLUSIONS
  Our results indicate that tau phosphorylation is not a direct result of anaesthesia per se, but it is due to anaesthesia-induced hypothermia and this leads to the inhibition of phosphatase activity as well as tau hyperphosphorylation. Tau hyperphosphorylation is associated with the observed deficits in spatial learning and memory following anaesthesia in hypothermic rats.
authors.affiliation: Department of Anaesthesiology, First Hospital, China Medical University, Shenyang, China.
authors.forename: Wenfei
authors.initials: W
authors.lastname: Tan
authors.forename: Xuezhao
authors.initials: X
authors.lastname: Cao
authors.forename: Junke
authors.initials: J
authors.lastname: Wang
authors.forename: Huangwei
authors.initials: H
authors.lastname: Lv
authors.forename: Binyang
authors.initials: B
authors.lastname: Wu
authors.forename: Hong
authors.initials: H
authors.lastname: Ma
mesh_terms: D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D003071:Cognition; D000939:Epitopes / Q000737:chemistry; D006624:Hippocampus / Q000378:metabolism; D007530:Isoflurane / Q000494:pharmacology*; D008297:Male; D018782:Maze Learning; D008568:Memory / Q000187:drug effects*; D008569:Memory Disorders / Q000378:metabolism; D010766:Phosphorylation; D054648:Protein Phosphatase 2 / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D016875:tau Proteins / Q000737:chemistry*
chemical_list: D018685:Anesthetics, Inhalation; D000939:Epitopes; D016875:tau Proteins; D007530:Isoflurane; D054648:Protein Phosphatase 2