Increased accumulation of cAMP in cerebral microvessels in Alzheimer's disease.

The objective of this study was to compare the adenylyl cyclase-cAMP second messenger system in cerebral microvessels isolated from Alzheimer's patients to that in microvessels from nondemented elderly controls. To evaluate the role of aging separate from the effects of dementia, microvessels from young and aged rodents were also examined. The results of this study indicated that microvessels isolated from autopsy material can be used to evaluate adenylyl cyclase activity. The data showed that cAMP levels, as an index of adenylyl cyclase activity, are significantly (p < 0.02) elevated in microvessels from Alzheimer's disease compared to nondemented elderly controls. Stimulation of adenylyl cyclase by forskolin was comparable in both groups of microvessels. A comparison of unstimulated microvessels from young and aged rodents yielded no significant difference in cAMP levels. These results indicate an increased level of cAMP in the microvessels of Alzheimer's patients with no age-related change demonstrable in rat microvessels.