MORPHOLOGICAL-STUDIES ON THE CENTRAL-NERVOUS-SYSTEM OF RATS WITH PORTACAVAL ANASTOMOSIS WHICH WERE CONTINUOUSLY INFUSED WITH AMMONIUM ACETATE

Morphological changes in the striatum of portacaval anastomosis (PCA) rats which were continuously infused with ammonium acetate for 6 days have been studied. PCA rats with the infusion of ammonium acetate show ed no neurological symptoms. However, ammonia concentration in the pla sma was significantly higher than that in PCA rats without the infusio n of ammonium acetate. Histologically, numerous atrophic neurons have been observed in the striatum. Moreover, glial fibrillary acidic prote in (GFAP)-positive astrocytes in the same area became hypertrophied an d had enlarged processes in hyperammonemic PCA rats. These results sug gest that long-term hyperammonemia, which did not produce any visible neurological symptoms, might induce the morphological changes in the b rain of PCA rats. These changes might be related to excessive ammonia metabolism in astrocytes.