Fig. 2.
Effects of intrathecal (i.t.) pretreatment of ondansetron (OND), a 5-hydroxytryptamine 3 receptor antagonist (0.3 or 3 μg), on intraperitoneal (i.p.) morphine (MOR)-induced analgesia (10 mg/kg) in normal (A) and spinal nerve ligation (SNL) rats (B). Time-course effects (A, B) and area under the time-course curve (AUC) (C) are shown. Withdrawal thresholds are expressed as the mean ± SD for six rats in each group. *P < 0.05 compared with the saline (SAL) plus morphine-treated group at each time point (two-way repeated-measures ANOVA followed by Student–Newman–Keuls post hoc tests). #P < 0.05 compared with the saline plus morphine-treated group (one-way ANOVA followed by Student–Newman–Keuls post hoc tests).