Effects of norBNI, (1,10 mg/kg), 5’-AMN (1 mg/kg), and 5’-MABN (1,10 mg/kg) on anxiety-related behaviour in mice. The time spent in open arms (A), number of entries into the open arms (B) and total ambulation (C) during a 5 min EPM test are shown. The time spent in the lit compartment during a 10 min LDB test is also shown (D). Anxiety-related behaviours were measured in the same groups of animals on successive days following a single injection of antagonist, and 30 min after diazepam (1 mg/kg) administration. Data are expressed as mean ± SEM, n=10 per group. Comparisons to saline:*P < 0.05, **P < 0.01.