Severe Acute Hepatic Dysfunction Induced by Ammonium Acetate Treatment Results in Choroid Plexus Swelling and Ventricle Enlargement in the Brain.

Hepatic encephalopathy is a major cause of liver failure. However, the pathophysiological role of ventricle enlargement in brain edema remains unclear. Here, we used an acute hepatic encephalopathy mouse model to examine the sequential pathological changes in the brain associated with this condition. We collected tissue samples from experimental animals treated with ammonium acetate at 3 and 24 h post-injection. Despite the normalization of the animal's ammonia levels, samples taken at 24 h after injection exhibited distinct enlargement of lateral ventricles. The choroid plexus samples obtained at 3 h post-ammonium acetate treatment indicated enlargement; however, this swelling was reduced at the later timepoint. The aquaporin-1 proteins that regulate the choroid plexus were localized both in the apical membrane and the cytoplasm of the epithelia in the control; however, they translocated to the apical membranes of the epithelia in response to ammonia treatment. Therefore, severe acute hepatic encephalopathy induced by ammonium acetate administration caused enlargement of the ventricles, through swelling of the choroid plexus and aquaporin-1 transport and aggregation within the apical membranes.