Potency ratios of morphine and mitragynine alone in the presence of various compounds to produce discriminative-stimulus, rate-decreasing, and antinociceptive effects in either morphine- or mitragynine-trained rats
Each potency ratio (95% CIs) is a combination of females and males unless otherwise noted. The ED50 values of morphine and mitragynine alone are shown in Table 4. The sample sizes are described in each figure legend (Figs. 7 –10). Significant differences are italicized.
| Rats Trained with Morphine | |||
|---|---|---|---|
| Test Compound | Discriminative Stimulus | Response Rate | Antinociception |
| 0.032 mg/kg Naltrexone + morphine vs. morphine alone | First: 8.22 (5.77–11.6). Reassessment: 9.50 (6.65–13.8) | First: 2.58 (1.68–4.45). Reassessment: 1.66 (1.08–2.81) | Not applicable |
| 0.032 mg/kg Naltrexone + 7-hydroxymitragynine vs. 7-hydroxymitragynine alone | 2.44 (1.46–9.69) | 1.29 (0.753–2.32) | Not applicable |
| 1.78 mg/kg Nalbuphine + morphine vs. morphine alone | First: 0.181 (0.0918–0.288). Reassessment: 0.209 (0.106–0.342) | First: 1.90 (1.33–2.86). Reassessment: 1.22 (0.855–1.80) | Not applicable |
| 5.6 mg/kg Mitragynine + morphine vs. morphine alone | First: 0.258 (0.120–0.327). Reassessment: 0.299 (0.139–0.387) | First: 0.854 (0.555–1.34). Reassessment: 0.549 (0.356–0.845) | Not applicable |
| Rats trained with mitragynine | |||
| 0.032 mg/kg Naltrexone + mitragynine vs. mitragynine alone | Not applicable | Not applicable | Not applicable |