Subchronic DE Exposure Differentially Regulates Other Cytokines and Chemokines in the Midbrain. Male Fischer 344 rats were exposed to either filtered air (control, 0 μg PM/m3 DE, n = 8), 35 μg PM/m3 DE (Low, n = 8), 100 μg PM/m3 DE (Mid Low, n = 8), 311 μg PM/m3 DE (Mid High, n = 8), or 992 μg PM/m3 DE (High, n = 8) for 6 months. (A) IL-1β, (B) IL-6, and (C) MIP-1α protein levels were measured in the midbrain by ELISA. An * indicates significant difference (p < 0.05) from control animals. DE elevated IL-1β at only the highest concentration of DE, failed to affect IL-6 levels, and decreased MIP-1α expression in the midbrain.