Top, effects of cumulative doses of cocaine in separate groups of rats
treated with saline (saline), 10 mg/kg morphine (10 MOR; redrawn from
Fig. 5), 10 mg/kg morphine + 10
mg/kg spiradoline (10 MOR + 10 SPR), and 10 mg/kg morphine + 10 mg/kg
spiradoline + 10 mg/kg nor-binaltorphimine (10 MOR + 10 SPR + 10 NBNI).
Bottom, effects of cumulative doses of cocaine in separate groups of rats
treated with saline (saline), 1.0 mg/kg buprenorphine (1.0 BUP; redrawn from
Fig. 5), 1.0 mg/kg
buprenorphine + 10 mg/kg spiradoline (1.0 BUP + 10 SPR), and 1.0 mg/kg
buprenorphine + 10 mg/kg spiradoline + 10 mg/kg nor-binaltorphimine (1.0 BUP +
10 SPR + 10 NBNI). Left, locomotor activity expressed as a percentage of
saline control values. Right, AUC estimates for each group. Horizontal lines,
significant differences between groups (p < 0.05). Vertical lines,
S.E.; where not indicated, the S.E. fell within the data point. Significant
differences are indicated as follows: a, significantly different from saline
control group (p < 0.05); and b, significantly different from
spiradoline-treated group (p < 0.05).