Temperature-regulated model of focal ischemia in the mouse: a study with histopathological and behavioral outcomes.
OBJECTIVE
The importance of mouse stroke models has increased with the development of genetically manipulated animals. We hypothesized that immediate postischemia hypothermia may attenuate ischemic brain injury in the mouse.


METHODS
Intraabdominal radio frequency probes were implanted in animals and core temperature monitored. Groups included: MCAO-45-REG (45 minutes middle cerebral artery occlusion [MCAO]) temperature-controlled in the postischemic period >34 degrees C for 24 hours; MCAO-45 (45 minutes MCAO) were allowed to self-regulate core temperature during recovery; MCAO-30-REG (30 minutes MCAO), with the same temperature protocol as MCAO-45-REG; MCAO-30 (30 minutes MCAO), with temperature protocol the same as MCAO-45. Behavior and histological score was assessed at 7 days. The qualitative histological score assessed for injury in 18 specified regions.


RESULTS
MCAO-45-REG core temperature (mean 34.94 degrees C+/-0.8 degrees C) was significantly different than the self-regulating (MCAO-45, mean 33.1 degrees C+/-2.3 degrees C) for the first 4 hours after anesthesia (P<0.01). There was a trend toward similar differences in temperatures for MCAO-30-REG and MCAO-30 (P=0.08). At 7 days, a greater improvement in behavior score was observed for MCAO-45 and MCAO-30 compared with MCAO-45-REG and MCAO-30-REG (P<0.001). The histological score confirmed reduced injury in unregulated temperature groups (MCAO-45-REG mean 38+/-10 and MCAO-45 30+/-5.1, P<0.05; MCAO-30-REG 41+/-10 and MCAO-30 30+/-9, P<0.05).


CONCLUSIONS
Hypothermia is an important confounder of stroke injury in the intraluminal filament mouse model. Future mouse stroke studies must use strict temperature regulation.
Barber
Philip A
PA
Department of Clinical Neurosciences, University of Calgary, Institute for Biodiagnostics, Room 153, 3330 Hospital Drive, Calgary, Edmonton, AB T2N 4N1 Canada. pabarber@ucalgary.ca
Hoyte
Lisa
L
Colbourne
Frederick
F
Buchan
Alastair M
AM
D000818:Animals; D001783:Blood Flow Velocity; D001784:Blood Gas Analysis; D001794:Blood Pressure; D002545:Brain Ischemia / Q000473:pathology / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D006979:Hyperthermia, Induced; D007035:Hypothermia / Q000503:physiopathology*; D051379:Mice; D023421:Models, Animal; D011597:Psychomotor Performance; D013696:Temperature