Figure 3

Microglial activation is involved in PDGF-BB-induced tactile allodynia. (A) The L5 spinal cord segments from PDGF-BB-administered rats at day 3 and 7 were subjected to immunohistochemistry using an anti-Iba1 antibody. Scale bar, 200 μm. (B) The number of Iba1-positive cells was counted in the dorsal horn. Data are means ± SEM of the cell number (day 3, n = 4; day 7, n = 3). **P < 0.01 vs vehicle by Student's t-test. (C) The magnified images of Iba1 staining at day 3. Scale bar, 20 μm. (D) Total RNA extracted from the L5 spinal dorsal horn 3 days after PDGF administration was subjected to quantitative analysis of interleukin-1β (IL-1β) mRNA expression by real-time RT-PCR. Data are means ± SEM of the fold change over vehicle control (n = 3). *P < 0.05 vs vehicle by Student's t-test. (E) The paw withdrawal thresholds of PDGF-BB (10 pmol)-administered rats were measured in a combined administration group with minocycline (100 μg, n = 4) or vehicle (PBS, n = 4). Minocycline or vehicle was intrathecally administered daily from one day before PDGF-BB administration. Data are means ± SEM of the thresholds. ***P < 0.001, **P < 0.01 vs before PDGF-BB administration; ^## P < 0.01, ^# P < 0.05 vs PDGF 10 pmol + vehicle group by Student's t-test. (F) Immunofluorescence for p-PDGFRβ in the L5 spinal dorsal horn 30 min after PDGF-BB (10 pmol) administration in minocycline- or vehicle-pre-administered rats. Minocycline or vehicle was intrathecally administered one day and 30 min before PDGF-BB administration. Scale bar, 200 μm.