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Exercise pretraining protects against cerebral ischaemia induced by heat stroke in rats
  1. Yu-Wen Chen1,
  2. Sheng-Hsien Chen2,
  3. Willy Chou3,
  4. Yi-Ming Lo3,
  5. Ching-Hsia Hung4,
  6. Mao-Tsun Lin2
  1. 1
    Department of Physical Therapy, China Medical University, Taichung, Taiwan
  2. 2
    Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan
  3. 3
    Department of Rehabilitation Medicine, Chi Mei Medical Center, Tainan, Taiwan
  4. 4
    Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan
  1. Dr C-H Hung, Department of Physical Therapy, National Cheng Kung University, No 1 Ta-Hsueh Road, Tainan 701, Taiwan; chhung{at}mail.ncku.edu.tw

Abstract

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°C for 55 min, which caused the body temperature to reach 42°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.

  • hyperthermia
  • heat stress
  • brain damage
  • exercise training
  • heat shock protein 72

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Footnotes

  • Competing interests: None.

  • C-H Hung and M-T Lin shared equal contribution with the corresponding author.

  • Abbreviations:
    3wk1D
    1 day after 3-week exercise training
    CBF
    cerebral blood flow
    HE
    heat exposure
    HR
    heart rate
    HS
    heat stroke
    HSP72
    heat-shock protein 72
    MAP
    mean arterial pressure
    NO
    nitric oxide
    NOS
    nitric oxide synthase
    NT
    normothermic control
    NTS
    nucleus tractus solitarii
    SED
    sedentary
    TB
    blanket temperature
    TCO
    colonic temperature

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