title: Delayed and prolonged post-ischemic hypothermia is neuroprotective in the gerbil.
abstract: Global ischemia, in the gerbil, produces profound hippocampal CA1 loss which leads to functional abnormalities (e.g. habituation impairment). In experiment 1, gerbils were subjected to 3 or 5 min of normothermic (brain) ischemia. Hypothermic groups were cooled to 32 degrees C for 12 h beginning 1 h after ischemia, while control groups (no hypothermia) regulated their own temperature. Exploration in a novel open field was assessed on days 3, 7 and 10 following ischemia and CA1 neurons were counted after 10- or 30-day survival. Both ischemia durations produced severe CA1 necrosis which resulted in increased open field activity. Hypothermia attenuated this behavioral pattern and substantially reduced CA1 necrosis against 3 min of ischemia when assessed at 10 and 30 days, but was only partially effective against a 5 min occlusion where, in addition, some cell death appeared to be delayed rather than prevented. In experiment 2, gerbils were occluded for 5 min and survived for 30 days. Twenty-four hours of hypothermia initiated 1 h after ischemia resulted in near total preservation of CA1 neurons. Thus, increasing the duration of post-ischemic hypothermia from 12 to 24 h produced much greater neuroprotection against severe ischemia. Prolonged post-ischemic hypothermia may be a valuable intervention in stroke patients.
authors.affiliation: Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada.
authors.forename: F
authors.initials: F
authors.lastname: Colbourne
authors.forename: D
authors.initials: D
authors.lastname: Corbett
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001831:Body Temperature; D005106:Exploratory Behavior; D005260:Female; D005849:Gerbillinae; D006624:Hippocampus / Q000473:pathology / Q000502:physiology / Q000503:physiopathology*; D007036:Hypothermia, Induced; D002546:Ischemic Attack, Transient / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D009336:Necrosis; D009474:Neurons / Q000473:pathology / Q000502:physiology*; D017966:Pyramidal Cells / Q000473:pathology / Q000502:physiology*; D012016:Reference Values; D013997:Time Factors