The six chronic treatment conditions and three testing conditions comprising the 18 distinct groups of rats in the tolerance and cross-tolerance experiments
| Chronic Treatment | Test Agonist |
|---|---|
| Etorphine | Etorphine |
| Etorphine | Morphine |
| Etorphine | Dezocine |
| Etorphine +LY235959 | Etorphine |
| Etorphine + LY235959 | Morphine |
| Etorphine + LY235959 | Dezocine |
| Morphine | Etorphine |
| Morphine | Morphine |
| Morphine | Dezocine |
| Morphine +LY235959 | Etorphine |
| Morphine + LY235959 | Morphine |
| Morphine+ LY235959 | Dezocine |
| Dezocine | Etorphine |
| Dezocine | Morphine |
| Dezocine | Dezocine |
| Dezocine +LY235959 | Etorphine |
| Dezocine + LY235959 | Morphine |
| Dezocine+ LY235959 | Dezocine |