Cilostazol but not sildenafil prevents memory impairment after chronic cerebral hypoperfusion in middle-aged rats.

We previously reported that the phosphodiesterase-5 (PDE5) inhibitor sildenafil prevented neurodegeneration but not learning deficits in middle-aged rats that were subjected to the permanent, three-stage, four-vessel occlusion/internal carotid artery (4-VO/ICA) model of chronic cerebral hypoperfusion (CCH). In the present study, we examined whether the PDE3 inhibitor cilostazol alleviates the loss of long-term memory (i.e.