CEREBRAL MICROVESSELS IN ALZHEIMERS HAVE REDUCED PROTEIN-KINASE-C ACTIVITY

Protein kinase C (PKC) is an important intracellular signalling enzyme . Numerous studies have suggested that alterations in this enzyme occu r in aging and dementia. The objective of this study was to examine PK C in the cerebral microcirculation in aging and Alzheimer's disease. P KC activity, amount, and isoform distribution were analyzed in microve ssels from adult and aged rodents as well as from Alzheimer patients a nd nondemented elderly controls. PKC activity was lower in Alzheimer v essels than in vessels from control brains, despite the presence of si milar levels of PKC enzyme. In contrast, both activity and enzyme leve ls in young and aged rats were comparable. The p-isoform was present i n both rat and human microvessels and there were no age- or disease-re lated alterations. The loss in activity in cerebromicrovascular PKC in Alzheimer's suggest that perturbations in phosphorylation signalling cascades may exist at the Alzheimer blood-brain barrier.