Establishment of a local cooling model against spinal cord ischemia representing prolonged induction of heat shock protein.
OBJECTIVE
Paraplegia is one of the serious complications of thoracoabdominal aortic operations. Regional hypothermia protects against spinal cord ischemia although the protective mechanism remains unknown. We attempted to create a simple model of local cooling under transient spinal cord ischemia and evaluated the effect using functional and histologic findings.


METHODS
Male domesticated rabbits were divided into 3 groups: control, normothermic group (group N), and local hypothermic group (group H). A balloon catheter was used for spinal cord ischemia by abdominal aortic clamping. A cold pack attached to the lumbar region could lower the regional cord temperature initially. Neurologic function was evaluated by the Johnson score. Cell damage was analyzed by observing motor neurons with the use of hematoxylin and eosin staining, terminal deoxynucleotidyl transferase-mediated deoxy-uracil triphosphate biotin in situ nick end labeling (TUNEL), and immunoreactivity of heat shock protein.


RESULTS
Physiologic estimation showed that local hypothermia improved the functional deficits (group N, 1.3 +/- 0.9; group H, 4.9 +/- 0.3; P =.0020). Seven days after reperfusion, there was a significant difference in the motor neuron numbers between groups N and H (group N, 7.2 +/- 1.9; group H, 20.4 +/- 3.2; P =.0090). The number of TUNEL-positive motor neurons was reduced significantly (group N, 7.2 +/- 2.4; group H, 1.0 +/- 0.7; P =.0082). Heat shock protein immunoreactivity was prolonged up to 2 days after reperfusion in the hypothermic group.


CONCLUSIONS
These results suggest that local hypothermia extended the production of heat shock protein in spinal cord motor neurons after reperfusion and inhibited their apoptotic change.
Motoyoshi
N
N
Departments of Cardiovascular Surgery and Neurology, Graduate School of Medicine, Tohoku University, Sendai, Japan.
Sakurai
M
M
Hayashi
T
T
Aoki
M
M
Abe
K
K
Itoyama
Y
Y
Tabayashi
K
K
D000818:Animals; D017209:Apoptosis; D004195:Disease Models, Animal; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D007036:Hypothermia, Induced; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D007511:Ischemia / Q000235:genetics / Q000378:metabolism* / Q000517:prevention & control; D008297:Male; D009046:Motor Neurons; D011817:Rabbits; D013116:Spinal Cord / Q000098:blood supply* / Q000378:metabolism; D018709:Statistics, Nonparametric
D018840:HSP70 Heat-Shock Proteins