Figure 8.

Behavioral analysis of locomotor function and pain-related behaviors. Intact animals demonstrated expected levels of locomotor function, but 30 d after SCI, BBB scores revealed partial recovery of locomotor function for injured animals (A). In SCI animals, i.t. delivery of vehicle (SCI+VEH) or minocycline (SCI+MIN) had no significant effect during the period of administration (indicated by thick line) or for 2 d after cessation of administration, indicating no activation or depression of motor function that could compromise testing of nociceptive thresholds. After SCI, mechanical paw withdrawal thresholds had significantly (⁺p < 0.05) decreased in all groups when compared with intact animals (B). Minocycline resulted in an immediate increase in mechanical thresholds for the duration of administration. This effect was significant (*p < 0.05). Immediately after cessation of administration (day 33), mechanical thresholds returned to predrug levels that were equivalent to untreated SCI animals. Thermal paw withdrawal latencies (C) were significantly (⁺p < 0.05) lowered after SCI. Minocycline resulted in an immediate and significant (*p < 0.05) increase in paw withdrawal latencies. Minocycline sustained increased latencies for the duration of its administration. After cessation of delivery, latencies returned to predrug levels, which persisted for the duration of the experiment. Integral analysis (D) revealed that minocycline resulted in a significantly (*p < 0.05) more robust modulation of mechanical nociception compared with thermal nociception. Error bars represent mean ± SD. sec, Seconds.