FIG. 6.

Brain expression of inflammatory cytokines (IL-6, TNF-α, IFN-γ, IL-4, and IL-10). (a) Total RNAs (0.5 μg) extracted from brain structures were subjected to RT-PCR. Amplicons were electrophoresed on an agarose gel and electrotransferred. Hybridization of the Southern blots using radiolabeled specific internal probes allowed the semiquantification of each PCR product. The results indicate that IFN-γ was expressed in all infected brain structures, while IL-4 expression was restricted to the hippocampus and hypothalamus. IL-10 mRNA was almost undetectable. (b) Expression of cytokines (IL-6 and TNF-α) was calculated as a fraction of that of G3PDH (normalized values) and then was expressed as an infected/sham-inoculated ratio. Mann-Whitney U test was then carried out on the results of three separate series of infection experiments and showed a significant increase (P < 0.05, indicated by asterisks in the shaded columns) of IL-6 only in the hippocampus and of TNF-α in almost all infected brain structures, except the cortex and brain stem. cx, cortex; mes, mesencephalon; hip, hippocampus; hyp, hypothalamus; bs, brain stem; cb, cerebellum; sc, spinal cord.