Cerebral Protective Effects by Anesthetics in a Model of Incomplete Forebrain Ischemia in the Rat : Comparative evaluation of thiopental, isoflurane, and mild cerebral hypothermia

The protective effects of thiopental, isoflurane, and mild cerebral hypothermia on neuronal injury following forebrain ischemia in rats were evaluated. The experimental groups include the control (1.2% isoflurane and pericranial temperature (PT) at 38℃ ) , the isoflurane (burst-suppression doses and PT at 38℃ ) , the thiopental (burst-suppression doses and PT at 38℃ ) , and the cerebral hypothermia (1.2% isoflurane and PT at 35℃ ) groups. Forebrain ischemia was induced by bilateral carotid artery occlusion with simultaneous hypotension for 10 min. Three days after ischemia, neurobehavior and neuronal injury (H&E stain) were evaluated. The neurobehavior in the cerebral hypothermia group showed less dysfunction compared to that in the control and the isoflurane groups. The histologic examination revealed the rostro-caudal gradient in the severity of ischemic damage. Among the control, thiopental, and isoflurane groups, there was no significant difference except for a subtle histologic improvement in the entorhinal cortex in the thiopental group. By contrast, neuronal injury in all regions was significantly less in the cerebral hypothermia group than in the other groups. The results indicate that thiopental may have cerebral protective effects in the area where ischemia was relatively mild, while isoflurane has no protective effects even when administered in burst-suppression doses. The results also indicate that the mild cerebral hypothermia provides apparent cerebral protection, which can not be explained solely by metabolic suppression.

脳虚血

脳保護

麻酔薬

脳低温

神経細胞障害