Fig. 1. ( A ) Dose-response curves illustrating the weak antinociceptive effect of intrathecal administration of gabapentin on behavioral activities in rats with acute pancreatitis induced by intraductal bradykinin infusion. Values are represented as the mean ± SEM for initial 10-min activity in a novel cage experience. The 0-μg dose represents the aCSF vehicle treated drug control group used for comparisons to the gabapentin treatment groups with Mann–Whitney U-tests (n = 6 for all doses, except n = 4 for the 200-μg dose). No significant differences were found. ( B ) Dose-response curves illustrating the weak antinociceptive effect of intrathecal administration of morphine (for doses less than 1 μg) on spontaneous behavioral activities in rats with acute pancreatitis induced by intraductal bradykinin infusion. Hind limb extension, a specific pain-related phenomenon, was significantly reduced at all doses. Values are represented as the mean ± SEM for initial 10-min activity in a novel cage experience. The 0-μg dose represents the aCSF vehicle treated drug control group. Comparisons were made between the vehicle and morphine treatment groups using Mann–Whitney U-tests. * P < 0.05; ** P < 0.01; n = 6 per dose.