REPEATED UNILATERAL CAROTID OCCLUSION IN MONGOLIAN GERBILS - QUANTITATIVE-ANALYSIS OF CORTICAL NEURONAL LOSS

To develop an experimental model which enables quantitative analysis o f chronic neuronal loss in the cerebral cortex, repeated ischemic insu lt was performed using unilateral carotid artery occlusion in Mongolia n gerbils. The effect of the time interval between the repeated ischem ic insult on the survival rate of the animals and the amount of cortic al neuronal loss were examined. The time course of the cortical neuron al damage in repeated ischemic insult was also studied. We repeated th e occlusion four times; i.e., one 10-min and three 7-min occlusions (t otal 31 min of ischemia). The number of animals surviving for 3 weeks after the last ischemic insult was minimum (15.4 %) for animals underg oing occlusions at 1-h intervals and maximum (100 %) at 24- and 48-h i ntervals. The number of ischemic neuronal deaths was also dependent up on the time interval, and it was so pronounced as to allow analysis at intervals of 12 hr or 24 hr in the absence of infarction in the corte x. The number of neuronal deaths could not be determined for animals w ith occlusion at 1-h intervals due to the production of a large infarc tion, with which the 3-week survival rate was minimum. The temporal pr ofile of cortical neuronal loss in the repeated ischemic insult at 24- h intervals indicated that the number of cortical neurons significantl y decreased until 7 days after the start of the ischemic procedure. Th is model is useful for clarifying the pathophysiology of chronically d eveloping ischemic neuronal death.