Pathobiology of Diabetic Encephalopathy in Animal Models

Abstract

This review will compare longitudinally the cognitive deficits and associated metabolic and structural abnormalities in two models with spontaneous onset of type 1 and type 2 diabetes, respectively. From these studies it is becoming increasingly evident that the cerebral dysmetabolism differs in many respects as to underlying mechanisms leading up to progressive cognitive dysfunction, although mechanistic overlaps exist between the two models. In the type 1 model, insulin deficiency appears to play a prominent role in degenerative and apoptotic phenomena of neuronal populations and white matter constituents. In these processes, undoubtedly, hyperglycemia and its downstream metabolic aberrations are also active participants. In the type 2 model, which reflects closely the situation in human type 2 diabetes, the underlying mechanisms appear more complex and are likely to include components of the metabolic syndrome such as hypercholesterolemia and hypertension. This model displays increased activity of the amyloidogenic processing of APP with subsequent accumulation of A(amyloid)beta products. This together with central insulin resistance is likely to be responsible for increased presence of hyperphosphorylated tau. Hence, in this model similarities with factors responsible for the progressive degenerative changes characterizing Alzheimer's disease are obvious. Although information to date is rather limited in genetically unmanipulated models of diabetes, available information stresses differences in the pathogeneses responsible for diabetic encephalopathy in the two types of diabetes will be reviewed. NR - 135 PU - HUMANA PRESS INC PI - TOTOWA PA - 999 RIVERVIEW DR, STE 208, TOTOWA, NJ 07512-1165 USA