Cognitive functions of carotid artery stenosis in the aged rat

Carotid artery stenosis appears to be an independent risk factor for cognitive impairment. But the mechanisms of cognitive impairments occurring in patients with asymptomatic carotid stenosis are poorly understood. One important reason is the absence of a good carotid stenosis model. In the present study, after establishing different degrees of carotid stenosis models in aged rats successfully, we investigated their cognitive function. Wistar rat models with carotid artery stenosis were established by ligating the common carotid artery along with various gauges of needle and then removing the needle. The cognitive performance was assessed using Morris water maze (MWM) task. Cholinergic markers like acetylcholine (ACh) were evaluated in hippocampus. Neuronal damage was also studied through morphological changes. Severe carotid stenosis led to impairment in learning ability and memory retrieval, accompanied with a decrease in ACh level and morphological damage in hippocampus. Moderate carotid stenosis rats had a partial cognitive impairment, but there were no changes in ACh level and morphological damage in hippocampus. Meanwhile, mild carotid stenosis rats had no cognitive impairment compared to sham-operated rats. The results of this study suggest that different degrees of carotid stenosis induce different cognitive changes in aged rats.