Intraischemic mild hypothermia prevents neuronal cell death and tissue loss after neonatal cerebral hypoxia-ischemia.
The effectiveness of hypothermia in preventing ischemic brain damage depends on when it is started. The purpose of this study was to investigate the effects of temperature reduction during a hypoxic-ischemic (HI) insult on brain injury and signalling pathways of neuronal cell death and survival. Seven-day-old mice were subjected to left common carotid artery ligation and hypoxia (10% oxygen) at different temperatures (37, 36 or 34 degrees C) for 50 min. Brain injury at 7 days post-HI was significantly reduced from 67.4% at 37 degrees C to 31.6% at 36 degrees C and 10% at 34 degrees C, with no observable injury in the cortex of the 34 degrees C group. Cytochrome c release, caspase-3 activation and apoptosis-inducing factor translocation from mitochondria to nuclei were all significantly inhibited after intraischemic temperature reduction. Concurrently, the cell survival signalling pathway involving Akt was significantly sustained (the phosphorylated form of Akt was maintained) when the hypoxia temperature was decreased. These results indicate that intraischemic hypothermia diminished apoptosis through inhibition of both caspase-dependent and caspase-independent neuronal cell death pathways and promoted cell survival by inhibition of phosphorylated Akt dephosphorylation in the neonatal brain, thereby preventing neuronal cell death.
Zhu
Changlian
C
Department of Pediatrics, The Third Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China. changlian.zhu@neuro.gu.se
Wang
Xiaoyang
X
Xu
Falin
F
Qiu
Lin
L
Cheng
Xiuyong
X
Simbruner
George
G
Blomgren
Klas
K
D000818:Animals; D000831:Animals, Newborn; D051033:Apoptosis Inducing Factor; D015153:Blotting, Western / Q000379:methods; D001921:Brain / Q000473:pathology; D001930:Brain Injuries / Q000209:etiology / Q000473:pathology* / Q000517:prevention & control*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002452:Cell Count; D016923:Cell Death; D003576:Electron Transport Complex IV / Q000378:metabolism; D007839:Functional Laterality; D007036:Hypothermia, Induced / Q000379:methods*; D020925:Hypoxia-Ischemia, Brain / Q000150:complications / Q000473:pathology*; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009474:Neurons / Q000473:pathology* / Q000502:physiology; D051058:Oncogene Protein v-akt / Q000378:metabolism; D013696:Temperature
D051033:Apoptosis Inducing Factor; D008869:Microtubule-Associated Proteins; C079240:Mtap2 protein, mouse; C494830:AIFM1 protein, mouse; D003576:Electron Transport Complex IV; D051058:Oncogene Protein v-akt; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases