Immunostaining for activated microglia in the entorhinal cortex. Highly activated microglial cells (B) that are typical of LPS infused rats were completely absent in the brains of rats infused with aCSF (A). NMDAR1-immunoreactive cells within the entorhinal cortex of rats infused with aCSF (C) were characterized by darkly stained cell bodies and dendritic arbors. Rats infused with LPS (D) showed reduce level of immunoreactivity. Scale bars: (A, B) 100 μm; (C, D) 25 μm.