Moderate hypothermia prevents brain stem oxidative stress injury after hemorrhagic shock.
BACKGROUND
The purpose of this study was to investigate the effects of temperature on oxidative stress in brain stem tissue induced by hemorrhagic shock. We researched the hemorrhagic oxidative stress at various core temperatures using reduced glutathione (GSH) levels and thiobarbituric acid-reactive substances (TBARS) as markers of lipid peroxidation in brain stem homogenate.


METHODS
Forty rats were divided into four groups, of which one constituted the nonbleeding normothermia control group. In all of the three study groups, 40% of estimated blood volume was removed while they were being held at normothermia, mild hypothermia (32 degrees C), or moderate hypothermia (28 degrees C). Parameters including mean arterial pressure, rectal temperature, and heart and breathing rates were monitored and recorded during the procedures. After an hour at shock state, tissue samples were removed by craniectomy.


RESULTS
The tissue levels of TBARS increased significantly in normothermic and mild hypothermic hemorrhagic shock groups (10.74 nmol/g and 8.26 nmol/g) as compared with the control group (3.50 nmol/g) (p < 0.001). However, the tissue TBARS level in the moderate hypothermia group was only minimally increased (4.53 nmol/g). GSH showed a slight decrease in normothermic and mild hypothermic bleeding rats, and were unchanged in the moderate hypothermic rats.


CONCLUSIONS
Moderate systemic hypothermia (28 degrees C) appears to protect brain stem tissue from oxidative stress during severe hemorrhagic shock in rats, as indicated by insignificant change in tissue TBARS and GSH concentrations. These results suggest antioxidant protective effects of moderate systemic hypothermia in metabolically active brain stem tissue during hemorrhagic shock. Similar effects in humans remain to be studied.
Department of Emergency, Ondokuz Mayis University School of Medicine, Samsun, Turkey. drguven@ixir.com
Hakan
H
Guven
Ramazan
R
Amanvermez
Zafer
Z
Malazgirt
Ekrem
E
Kaya
Zahide
Z
Doganay
Cemil
C
Celik
Kayhan
K
Ozkan
D000818:Animals; D001810:Blood Volume; D001923:Brain Chemistry; D001933:Brain Stem / Q000098:blood supply* / Q000737:chemistry; D002560:Cerebrovascular Circulation; D004195:Disease Models, Animal; D005978:Glutathione / Q000032:analysis; D007035:Hypothermia / Q000145:classification / Q000150:complications* / Q000378:metabolism; D007036:Hypothermia, Induced / Q000379:methods*; D002534:Hypoxia, Brain / Q000209:etiology* / Q000378:metabolism / Q000401:mortality / Q000517:prevention & control*; D015227:Lipid Peroxidation; D008297:Male; D018384:Oxidative Stress / Q000502:physiology; D010101:Oxygen Consumption; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012720:Severity of Illness Index; D012771:Shock, Hemorrhagic / Q000150:complications* / Q000628:therapy*; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis
D017392:Thiobarbituric Acid Reactive Substances; D005978:Glutathione