Repeated administration of paclitaxel increases expression of the microglial activation markers OX-42 and OX-6, but not of the astrocyte marker GFAP, in lumbar (L5/L6) spinal cord. Rats received i.p. injections of vehicle or paclitaxel (cumulative dose 8 mg/kg) on alternate days, and were sacrificed on Day 35 or 42 to collect tissues for immunohistochemistry analysis. Representative photomicrographs are shown of GFAP (A, B) and OX-42 (C, D) immunoreactivity in the dorsal horn, and of OX-42 (E, F) and OX-6 (G, H) immunoreactivity in the ventral part of the lumbar spinal cord of rats treated with vehicle (A, C, E, G) or paclitaxel (B, D, F, H). Scale bar is 100 μm in E and F, and 200 μm in A-D, G, H.