Permanent occlusion of bilateral internal carotid arteries produces cognitive deficits in two learning behavior tasks

We investigated the effects of permanent bilateral occlusion of the internal carotid arteries (2ICAO) on the learning and memory performances in rats to evaluate the permanent 2ICAO rats as a model for vascular dementia. The learning and memory performance was tested by a step-through passive avoidance task and an 8-arm radial maze task. Permanent 2ICAO decreased cerebral blood flows in the cortex and hippocampus by 46.3 +/- 3.3 and 21.1 +/- 4.6%, respectively, when measured at 15 min after occlusion. In the passive avoidance task, the 2ICAO rats showed no impairment of learning or of memory retention when tested 1 h after learning trial, while they showed a shorter latency than sham-operated rats when tested 24 h after learning trial. In the radial maze learning task, the non-pretrained 2ICAO rats showed impairment. The pretrained 2ICAO rats had no deficit in the radial maze retention task but they showed impaired performance when a 3-min delay was interposed in the task. These results suggest that permanent 2ICAO is a useful animal model for studying vascular dementia.