title: The effect of hypothermia on the expression of the apoptosis-regulating protein Bax after incomplete cerebral ischemia and reperfusion in rats.
abstract: This study investigated the effects of hypothermia on apoptosis-regulating proteins in a rat model of incomplete cerebral ischemia. Twenty-seven fasted male Sprague-Dawley rats (300-420 g) were anesthetized, intubated, and mechanically ventilated with 2.0% isoflurane and N(2)O/O(2) (FiO(2) = 0.33). Catheters were inserted and cerebral blood flow velocity was measured using bilateral laser Doppler flowmetry. At the end of preparation, the administration of isoflurane was replaced by fentanyl (25 microg. kg(-1). h(-1)). Animals were randomly assigned to one of the following groups: group 1 (n = 9, normothermia), normothermia (37.5 degrees C) during ischemia; group 2 (n = 9, hypothermia), 34 degrees C pericranial temperature during ischemia; and group 3 (n = 9, sham-operated animals), normothermia, no cerebral ischemia. Ischemia (30 minutes) was produced by unilateral common carotid artery occlusion plus hemorrhagic hypotension (mean arterial blood pressure 30-35 mm Hg). Arterial blood gas tensions and pH were maintained constant. Four hours after 30 minutes of incomplete cerebral ischemia, the brains were removed for determination of the expression of the apoptosis-regulating proteins Bax, Bcl-2, p53, and Mdm-2 using immunofluorescence and Western blot analysis. Four hours after cerebral ischemia there was a significant increase in the expression of the pro-apoptotic protein Bax in normothermic animals compared with hypothermic (85-260%) and sham-operated animals (60-190%). The proteins Bcl-2, p53, and Mdm-2 showed no statistically significant differences between the groups or between the hemispheres. In conclusion, hypothermia during ischemia decreased Bax protein expression that is associated with programed cell death. This suggests that neuroprotection seen with hypothermia may be related to a reduction of pro-apoptotic events.
authors.affiliation: Klinik für Anaesthesiologie and section sign Institut für Experimentelle Onkologie und Therapieforschung, Technische Universität München, Klinikum rechts der Isar, Neuherberg, Germany. e.eberspaecher@lrz.tu-muenchen.de
authors.forename: Eva
authors.initials: E
authors.lastname: Eberspächer
authors.forename: Christian
authors.initials: C
authors.lastname: Werner
authors.forename: Kristin
authors.initials: K
authors.lastname: Engelhard
authors.forename: Monika
authors.initials: M
authors.lastname: Pape
authors.forename: Adrian
authors.initials: A
authors.lastname: Gelb
authors.forename: Peter
authors.initials: P
authors.lastname: Hutzler
authors.forename: Julia
authors.initials: J
authors.lastname: Henke
authors.forename: Eberhard
authors.initials: E
authors.lastname: Kochs
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western; D002545:Brain Ischemia / Q000235:genetics* / Q000473:pathology; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation / Q000502:physiology*; D006439:Hemodynamics / Q000502:physiology; D007036:Hypothermia, Induced; D017078:Laser-Doppler Flowmetry; D008297:Male; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D019253:Proto-Oncogene Proteins c-bcl-2; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000235:genetics* / Q000473:pathology; D013997:Time Factors; D051028:bcl-2-Associated X Protein
chemical_list: C494828:Bax protein, rat; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein