Fig. 6

Effect of oxaliplatin on TRPA1 mRNA as seen with in situ hybridization histochemistry in rat DRG (L_4–6) neurons. a Oxaliplatin (6 mg/kg, i.p.) increases the co-localization between TRPA1 and p-p38 MAP kinase in rat DRG (L_4–6) neurons. The photomicrographs show representative data. Co-localization of TRPA1 mRNA (green) and p-p38 MAPK (red) is shown. Double-labeled neurons (arrowheads) appear yellow in the merged panel. b Histogram shows the percent of TRPA1 mRNA-positive neurons relative to p-p38-positive neurons. TRPA1 mRNA and p-p38 co-localization was significantly higher on day 2 after oxaliplatin administration (6 mg/kg, i.p.) compared to 5 % glucose treatment. Data are the mean ± SEM. n = 4 each for 5 % glucose and oxaliplatin administration. *P < 0.05 versus 5 % glucose. c Size distribution of TRPA1 mRNA- and p-p38 MAPK-co-expressing neurons in DRGs in 5 % glucose- and oxaliplatin-treated rats. TRPA1 mRNA and p-p38 MAPK-co-expressing neurons were distributed among all sizes of neurons, but most co-expression was found in small DRG neurons. Data are the mean ± SEM. n = 4 each for 5 % glucose treatment and oxaliplatin treatment (6 mg/kg, i.p.). d Intrathecal administration of the p38 MAPK inhibitor, SB203580 (0.5 μg μL⁻¹ h⁻¹), significantly prevents the acute cold hypersensitivity induced by oxaliplatin (6 mg/kg, i.p.). The acetone spray test at day 2 after oxaliplatin was measured in SB203580 and 20 % DMSO treatment groups. Data are the mean ± SEM. n = 4 each for 20 % DMSO treatment and oxaliplatin treatment (6 mg/kg, i.p.). **P < 0.01 versus DMSO. ^##P < 0.01 versus oxaliplatin