title: Very Mild Hypothermia (35°C) Postischemia Reduces Infarct Volume and Blood/Brain Barrier Breakdown Following tPA Treatment in the Mouse.
abstract: Reperfusion therapies for stroke diminish in effectiveness and safety as time to treatment increases. Hypothermia neuroprotection for stroke is established, but its clinical translation has been hampered by uncertainties regarding optimal temperature and complications associated with moderate hypothermia. Also, hypothermia targeting temperatures of 32-33°C is associated with clinical and logistical problems related to induction and adverse side effects. We hypothesized that ischemic damage and tPA-exacerbated blood/brain barrier (BBB) breakdown produced following 30 minutes of middle cerebral artery occlusion and either 1 hour of saline or tPA infusion would be reduced by treatment with very mild cooling of 1.5°C for 48 hours followed by 24 hours of gradual rewarming. Infarct volume was reduced by 29.6% (p<0.001) and 41.9% (p<0.001) in hypothermic-tPA (Hypo_tPA)-treated and hypothermic-saline (Hypo_Sal)-treated animals compared to normothermic-tPA (Norm_tPA) and saline (Norm_Sal)-treated animals, respectively. Hypothermia also reduced IgG extravasation in tPA-treated, but not saline-treated groups compared to their normothermic controls (p<0.001). The ipsilateral-contralateral changes in optical density for IgG extravasation were 18.4% greater in the Norm_tPA than Norm_Sal (p<0.001) group. The ipsilateral-contralateral changes in optical density for IgG extravasation were reduced by 17.8% (p<0.001) in the Hypo_tPA compared to Norm_tPA group. No significant mean difference in IgG extravasation was seen between Hypo_tPA and Hypo_Sal groups (p>0.05). Very modest hypothermia to reduce the BBB breakdown could improve the availability and safety of reperfusion treatments for stroke.
authors.affiliation: Department of Clinical Neurosciences, Faculty of Medicine, Experimental Imaging Centre and Hotchkiss Brain Institute, University of Calgary , Calgary, Canada .
authors.forename: Brian K
authors.initials: BK
authors.lastname: Cechmanek
authors.affiliation: Department of Clinical Neurosciences, Faculty of Medicine, Experimental Imaging Centre and Hotchkiss Brain Institute, University of Calgary , Calgary, Canada .
authors.forename: Ursula I
authors.initials: UI
authors.lastname: Tuor
authors.affiliation: Department of Clinical Neurosciences, Faculty of Medicine, Experimental Imaging Centre and Hotchkiss Brain Institute, University of Calgary , Calgary, Canada .
authors.forename: David
authors.initials: D
authors.lastname: Rushforth
authors.affiliation: Department of Clinical Neurosciences, Faculty of Medicine, Experimental Imaging Centre and Hotchkiss Brain Institute, University of Calgary , Calgary, Canada .
authors.forename: Philip A
authors.initials: PA
authors.lastname: Barber
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D001833:Body Temperature Regulation; D001921:Brain / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D001929:Brain Edema / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control; D002199:Capillary Permeability; D019610:Cytoprotection; D004195:Disease Models, Animal; D005343:Fibrinolytic Agents / Q000008:administration & dosage / Q000633:toxicity*; D007036:Hypothermia, Induced / Q000379:methods*; D007074:Immunoglobulin G / Q000378:metabolism; D020244:Infarction, Middle Cerebral Artery / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008810:Mice, Inbred C57BL; D012965:Sodium Chloride / Q000008:administration & dosage*; D015912:Thrombolytic Therapy / Q000009:adverse effects*; D013997:Time Factors; D010959:Tissue Plasminogen Activator / Q000008:administration & dosage / Q000633:toxicity*
chemical_list: D005343:Fibrinolytic Agents; D007074:Immunoglobulin G; D012965:Sodium Chloride; D010959:Tissue Plasminogen Activator