Figure 7. Bars represent the area under the time-effect curve (AUC) for thermal escape latency after the intrathecal injections of substance P (IT sP) with different treatments. As indicated in the legend under the histogram, rats received vehicle (saline), D-serine, or L-serine 60 min before IT sP, and they received intraperitoneal (IP) gabapentin (100 mg/kg) or IP S(+)-3-isobutyl-GABA (3-IB-GABA; 30 mg/kg) 15 min before IT sP. One-way analysis of variance revealed highly significant differences between groups. Post hoc comparisons showed that, compared with IT sP alone, gabapentin and S(+)-3-butyl-GABA significantly reduced the negative AUC (hyperalgesia), and this was prevented in both cases by D-serine but not by L-serine (*P < 0.05 compared with IT sP alone).