Exercise pretraining protects against cerebral ischaemia induced by heat stroke in rats.
BACKGROUND
In the rat brain, heat-stroke-induced damage to cerebral neurons is attenuated through heat-shock-induced overexpression of heat-shock protein 72 (HSP72).


OBJECTIVE
To ascertain whether progressive exercise preconditioning induces HSP72 expression in the rat brain and prevents heat-stroke-induced cerebral ischaemia and injury.


METHODS
Male Wistar rats were randomly assigned to either a sedentary group or an exercise group. Those in the exercise group progressively ran on a treadmill 5 days/week, for 30-60 min/day at an intensity of 20-30 m/min for 3 weeks. The effects of heat stroke on mean arterial pressure, cerebral blood flow, brain ischaemia markers (glutamate, lactate/pyruvate ratio and nitric oxide), a cerebral injury marker (glycerol) and brain neuronal damage score in the preconditioned animals were compared with effects in unexercised controls. Heat stroke was induced by exposing urethane-anaesthetised animals to a temperature of 43 degrees C for 55 min, which caused the body temperature to reach 42 degrees C.


RESULTS
Three weeks of progressive exercise pretreatment induced HSP72 preconditioning in the brain and conferred significant protection against heat-stroke-induced hyperthermia, arterial hypotension, cerebral ischaemia and neuronal damage; it also prolonged survival.


CONCLUSIONS
Exercise for 3 weeks can improve heat tolerance as well as attenuate heat-stroke-induced cerebral ischaemia in rats. The maintenance of mean arterial pressure and cerebral blood flow at appropriate levels in the rat brain may be related to overexpression of HSP72.
Chen
Yu-Wen
YW
Department of Physical Therapy, China Medical University, Taichung, Taiwan.
Chen
Sheng-Hsien
SH
Chou
Willy
W
Lo
Yi-Ming
YM
Hung
Ching-Hsia
CH
Lin
Mao-Tsun
MT
D000818:Animals; D015153:Blotting, Western; D001831:Body Temperature / Q000502:physiology; D002545:Brain Ischemia / Q000517:prevention & control*; D002560:Cerebrovascular Circulation / Q000502:physiology; D050884:HSP72 Heat-Shock Proteins / Q000378:metabolism*; D006339:Heart Rate / Q000502:physiology; D018883:Heat Stroke / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D009474:Neurons / Q000473:pathology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar
D050884:HSP72 Heat-Shock Proteins