Quantitative changes in astrocytes after portacaval shunting in chimpanzees and in man with normal liver parenchyma.

Chimpanzees without liver cell damage, but subjected to portacaval anastomosis, showed behavioral changes that were accompanied by "Alzheimer II" astrocyte hyperplasia and nuclear enlargement. These findings were similar to those in a human patient with encephalopathy, secondary to a portacaval shunt, whose liver was normal. Controlled quantitative study of astrocytic hyperplasia in different anatomic regions showed the hyperplasia to involve the gray matter with only moderate topographic variation. Individual degrees of hyperplasia somewhat paralleled the severity of clinical symptoms and ammonia levels; no clear-cut relationship with time after shunting could be established. Portacaval shunt encephalopathy in chimpanzees greatly resembles that in man and, thus, lends itself to more detailed experimental analysis.