Alzheimer-type I astrogliopathy (AIA) and its implications for dynamic plasticity of astroglia: a historical review of the significance of AIA.

Alzheimer-type I astrogliopathy (AIA) is an uncommon neuropathological phenomenon encountered in Wilson's disease and less often in acquired hepatic encephalopathy. Since its first description in 1912 it has received little attention. However, after 1971, when the nature of its morphogenesis began to be recognized and it was shown that it could be reproduced experimentally, its significance has been increasingly appreciated. Two intriguing characteristics of the dynamic plasticity of astroglia were revealed from the studies of the inter-relationships between AIA and Alzheimer-type II astrogliopathy (AIIA); normal astroglia and AIIA; and reactive astrogliosis and AIIA, namely, the compensatory "rebound" phenomenon of Alzheimer astrogliopathy, and a dual cellular origin for reactive astrogliosis taking place in both normal and dystrophic astrocytes. More recently the presence of AIA and AIIA has been reported in a case of anoxic encephalopathy, and also in a case of Marchiafava-Bignami's disease. In this review, dependable criteria for the identification of the pathological features of AIA are discussed and emphasized. Both types of Alzheimer astrogliopathy may be used as pathologic markers with specific morphological and immunocytochemical characteristics to study in detail the disturbances of metabolic interactions between the astrocyte-neuron coupling and the exact mechanisms of the dynamic plasticity of astroglia.