ED50 values, μg, (95% confidence interval) for i.c.v. heroin given 10 min before the tail-flick test (alone or with treatment with opioid antagonists) in inbred strains of mice
| Strain | i.c.v. heroin | +β-FNA2-a | +Naltrindole2-b | +N-BNI2-c |
|---|---|---|---|---|
| C57BL/6J | 1.2 (0.6–2.2) | 1.4 (0.8–2.5) | 5.5 (3.1–10)2-d | 1.9 (1.1–3.3) |
| CBA/J | 0.5 (0.2–1.2) | 1.5 (1.1–2.1)2-d | 0.4 (0.2–0.9) | 0.7 (0.4–1.0) |
| DBA/2J | 0.7 (0.3–1.5) | 2.6 (1.3–5.1)2-d | 0.4 (0.2–1.0) | 0.8 (0.3–2.3) |
| C3H/HeJ | 0.8 (0.4–1.3) | 1.5 (1.2–2.0)2-d | 0.8 (0.5–1.5) | 1.3 (1.0–1.7) |
| BALB/cByJ | 1.9 (1.1–3.2) | 1.9 (1.1–3.3) | 1.9 (1.1–3.2) | 9.5 (4.3–21)2-d |
| AKR/J | 2.1 (1.0–5.4) | 2.6 (1.5–4.7) | 2.8 (1.6–4.8) | 7.7 (5.9–10.1)2-d |
↵2-a β-FNA, 25 ng, i.c.v., 24 h before tail-flick test.
↵2-b Naltrindole, 10 μg, i.c.v., given in same solution with heroin.
↵2-c N-BNI, 10 μg, i.c.v. given in same solution with heroin.
↵2-d Indicates significant difference from heroin alone (P ≤ .05) according to comparison of ED50values, as in Methods.