Cerebral ischemia model using mongolian gerbils-comparison between unilateral and bilateral carotid occlusion models.

We permanently occluded unilaterally and/or bilaterally the carotid arteries of anesthetized Mongolian gerbils (60-80 g) and compared the two models. In the former, stroke-positive animals were selected by calculating the stroke index score of the conscious animals. Selection was not made in the latter. We measured the rCBF of the cerebral cortex, hippocampus, and diencephalon using the (3)H-nicotine scintillation method; analyzed the EEG using the wave-form recognition method (Fujimori); measured ATP, PCr (phosphocreatine), lactate, and glucose content in the cerebral hemisphere using the Lowry method; and measured infarct size on HE-stained coronal sections. All parameter values were uniform in the gerbils of the unilateral model, whereas great variation was observed in the right and left cerebral cortex, hippocampus, and diencephalon in the bilateral occlusion model. Therefore, we have discarded the bilateral model and used the stroke-positive unilateral model only.By changing the length of time of the unilateral carotid occlusions and intervals, we found that two 10-min unilateral carotid occlusions with a 5-h interval between them achieved a threshold ischemic insult in gerbils, which produced uniform cortical focal infarctions that evolved in the maturing DSNN on the coronal surface sectioned at the chiasmatic level (Face A). This model showed a marked reduction in the occurrence of ischemic epilepsy and death.