Blood–brain barrier breakdown induced by the intrastriatal injection of cytokines and chemokines, as indicated by the extravasation of immunoglobulins. (a-l) Cerebral hemispheres from juvenile NMO-IgG seropositive Lewis rats stained for the presence of rat immunoglobulins (brown; a-f) and adjacent sections stained for the presence of human immunoglobulins (brown; g- l) 20–24 hrs after intrastriatal injections of 0.3 μl PBS containing 30 ng of IL-1β (a,g), TNF-α (b,h), IFN-γ (c,i), CXCL2 (d,j), IL-6 (e,k) or no further additives (f,l). The differences of IgG leakage between the different experimental groups was not significant. Dashed line: needle tract. Scale bar: 1 mm.