Behavioral, electroencephalographic and histopathological studies on mongolian gerbils with occluded common carotid arteries.

The effect of brain ischemia on passive avoidance test was investigated in mongolian gerbils with ischemia induced by a 5 min bilateral occlusion of the carotid arteries. Severe impairment of memory was apparent when the training session of the passive avoidance test was carried out 2 or 14 days after the bilateral ischemia. Two days after the occlusion, the amplitude of hippocampal theta waves were slightly decreased and Nissl's degradation was apparent in the CA1 neurons in the hippocampus. The changes in hippocampal neurons become progressively more severe. The amplitude of the hippocampal theta waves diminished considerably and the CA1 neurons in the hippocampus disappeared 14 days after the occlusion. We suggest that the hippocampal damage, especially abnormalities in the CA1 neurons, evidenced by histopathological and electroencephalographic results, may be related to deficits in memory following bilateral common carotid arteries occlusion.