Figure 2. Thermally evoked hind paw withdrawal latency measured before and after the intrathecal injections of substance P (IT sP) at time = 0 min. Gabapentin (100 mg/kg) or S(+)-3-isobutyl-GABA (30 mg/kg) was injected intraperitoneally 60 min before the delivery of the IT sP. Each line represents the mean +/- SEM of six rats. Repeated-measures analysis of variance revealed a significant main effect for time for the group of rats receiving IT sP (P > 0.001). In contrast, there was no change in the escape latencies over time for groups receiving IT sP + gabapentin or IT sP + S(+)-3-isobutyl-GABA (P > 0.10). Therefore, at these doses, intraperitoneal gabapentin and S(+)-3-isobutyl-GABA prevented the hyperalgesia induced by IT sP.