Injury severity and cell death mechanisms: effects of concomitant hypovolemic hypotension on spinal cord ischemia-reperfusion in rats.
A number of previous studies indicated that ischemia-reperfusion injury causes two distinct types of cell death--necrosis and apoptosis--in the central nervous system. It was also implicated that the intensity of injury can somehow affect the cell death mechanisms. By occluding the descending thoracic aorta with or without simultaneously induced hypovolemic hypotension in rats, we established a model of experimental spinal cord ischemia-reperfusion (I/R) in which the injury severity can be controlled. Recordings of carotid blood pressure (CBP) and spinal cord blood flow (SCBF) showed that aortic occlusion induced dramatic CBP elevation but SCBF drop in both the normotensive (NT) and hypotensive (HT) groups of rats. However, the HT group demonstrated significantly lower SCBF during aortic occlusion, and much slower elevation of SCBF after reperfusion, and extremely poor neurological performance. Spinal cord lesions were characterized by infarction associated with extensive necrotic cell death, but little apoptosis and caspase-3 activity. In contrast, in the NT group, I/R injury resulted in minor tissue destruction associated with persistent abundant apoptosis, augmented caspase-3 activity, and favorable functional outcome. The relative sparing of motoneurons in the ventral horns from apoptosis might have accounted for the minor functional impairment in the NT group. The severity of I/R injury was found to have substantial impact on the histopathological changes and cell death mechanisms, which correlate with neurological performance. Our results implicate that injury severity and duration after injury are two critical factors to be considered in therapeutic intervention.
Lu
Kang
K
Department of Neurosurgery, Chang Gung Memorial Hospital, Kaohsiung Medical Center, Taiwan.
Liang
Cheng-Loong
CL
Chen
Han-Jung
HJ
Chen
Shang-Der
SD
Hsu
Huan-Chen
HC
Liliang
Po-Chou
PC
Lin
Tsu-Kung
TK
Cho
Chung-Lung
CL
D000818:Animals; D001013:Aorta, Thoracic / Q000503:physiopathology; D001794:Blood Pressure; D015153:Blotting, Western; D002339:Carotid Arteries / Q000503:physiopathology; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D016923:Cell Death; D002470:Cell Survival; D004195:Disease Models, Animal; D007022:Hypotension / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D020896:Hypovolemia / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008297:Male; D009474:Neurons / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow; D015427:Reperfusion Injury / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D013116:Spinal Cord / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology*; D020760:Spinal Cord Ischemia / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D015996:Survival Rate
C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases