CD4 and Hyperammonemia: These results show that, in hyperammonemia, EV released by monocytes (HA-M-EV) but not those released by CD4+ lymphocytes (HA-CD4-EV) induce glial activation in control rats similar to that observed in hippocampal slices from hyperammonemic rats and would play a significant role in the pathological effects on neuroinflammation in the hippocampus in hyperammonemic rats.