Typical photomicrographs representing NOS histochemistry staining of neurons in the spinal cord. Oxaliplatin (4 mg/kg) was administered i.p. twice a week for 4 weeks (Days 1, 2, 8, 9, 15, 16, 22 and 23). On Day 25, Ro 25-6981 (300 nmol/body) was administered intrathecally, and the L4-6 spinal cord was removed 30 min after administration. NADPH diaphorase staining was performed to confirm NOS activity. The blue staining shows NADPH diaphorase staining. Spinal slices (30 μm) were prepared from rats treated with vehicle (A), oxaliplatin alone (B), and oxaliplatin and Ro 25-6981 (C). Scale bar, 200 μm.