Experimental groups and treatments. Intranigral injections of vehicle (Veh) or lipopolysaccharide (LPS) were given at day 1. In the stressed groups (S, SL and SLR), intranigral injections were carried out after the application of the first stressor (10 minutes of forced swimming). In the SLR group, RU486 (mifepristone (11β-[p-(dimethylamino)phenyl]-17β-hydroxy-17-(1-propynyl)estra-4,9-dien-3-one)) was injected subcutaneously every day 1 hour before the stressor. V, vehicle; S, stress; L, lipopolysaccharide; SL, lipopolysaccharide injected into stressed animals; SLR, lipopolysaccharide injected into stressed animals treated with RU486.