Table 4.
Influence of spinal 6-hydroxydopamine (6-OHDA) pretreatment on the effect of low-dose atipamezole on acute tolerance
| Pretreatment | Treatment | Tail flick ED50 (μg; i.t.) | Paw pressure ED50 (μg; i.t.) |
|---|---|---|---|
| Vehicle | Vehicle | 5.2±0.1*** | 7.1±1.2*** |
| Vehicle | Morphine (15 μg) | 24.5±0.8 | 25.5±1.5 |
| 6-OHDA | Morphine (15 μg) | 27.8±1.3 | 29.8±1.3 |
| 6-OHDA | Morphine+Atipamezole (0.08 ng) | 6.4±0.6*** | 5.3±0.8*** |
The morphine ED50 values were obtained from the cumulative dose–response curves for the antinociceptive action of the opioid agonist 24 h after termination of drug treatment in the animal groups represented in Figures 9a and b.
The data presented are means±s.e.mean; n=6–7 animals per treatment group.
Significant difference from the morphine (15 μg) group ***(P<0.001).