3,6′-Dithiothalidomide (56 mg/kg i.p.) treatment suppresses the activation of microglial cells induced by the intercerebroventricular administration of LPS. Representative flat images of staining for activated microglial cells in the dentate gyrus (DG) and CA3 areas of rat hippocampus are shown. The upper panel illustrates high numbers of activated microglial cells after treatment with LPS. The lower panel illustrates that drug treatment attenuates the numbers of LPS-induced activated microglia. Microglia are stained red; nuclei are counterstained green. The scale bar indicates 100 μm.