Figure 1

TH-positive neurons are more resistant to MPTP in mice treated with a selective COX-2 inhibitor (valdecoxib). A: Photomicrographs of representative SNpc sections stained with an antibody against TH. The SNpc tissues were collected 14 days post-MPTP injection. The MPTP (4 × 15 mg/kg, 1.5 hr interval, i.p.)-treated mice have fewer TH-positive neurons compared to the saline groups. However, valdecoxib treatment reduced the neuronal loss, especially at a higher dose (30 or 50 mg/kg daily). B: MPTP administration led to significant loss of TH-positive neurons numbers by 78 percent for vehicle and by only about 68, 56, and 42 percent for 10, 30 and 50 mg/kg valdecoxib-treated mice, respectively. Among the MPTP-injected mice, the valdecoxib-treated mice had 10 to 32 percent more TH-positive neurons than the vehicle-treated mice. Nissl stain shows similar trends (C&D). E: Inhibition of COX-2 reduced the MPTP-induced loss of the striatal TH immunoreactivity. F: After MPTP treatment, the vehicle-treated mice had significantly reduced TH immunoreactivity compared to the saline-treated mice (***p < 0.001). Among the MPTP-injected mice, the valdecoxib (30 mg/kg daily)-treated mice had at least 30% higher TH immunoreactivity than the vehicle-treated mice. Data are means ± SEM for six to eight mice per group, **p < 0.01 and ***p < 0.001 compared to saline+vehicle group; #p < 0.05, ##p < 0.01 and ###p < 0.001 compared to MPTP+vehicle group, by ANOVA with subsequent Bonferroni for multiple comparisons. Scale bar, 100 μm.