Fig. 6. Left hind paw withdrawal thresholds up to 21 days after spinal nerve ligation. Animals received two (4-h treatment) (solid circles ) or four (8-h treatment) (solid triangles ) postoperative doses of 100 μg SC-560 (A ) or 100 μg SC-236 (B ) given intrathecally, beginning 2 h after spinal nerve ligation. Each point represents the mean ± SEM of six animals. Asterisks indicate significant difference from preligation values (P < 0.05).