Involvement of transmitters in the anxiolytic action of urocortin 3 in mice.

Urocortin 3 (Ucn 3) was tested for anxiolytic action in mice an elevated plus maze. For detection of the possible involvement of neurotransmitters, the mice were pretreated with receptor blockers: haloperidol, phenoxybenzamine, propranolol, atropine, methysergide, bicuculline or naloxone. The peptide was administered into the lateral brain ventricle; the receptor blockers were applied intra- peritoneally. Ucn 3 alone elicited dose-dependent bell-shaped anxiolytic action. The most effective dose was 0.5 μg. In the combined testing a 0.5 μg dose was used. Haloperidol, propranolol, atropine, methysergide, and naloxone, blocked the Ucn 3-induced anxiolytic action, while phenoxybenzamine and bicuculline were ineffective. The results suggest that dopaminergic, beta-adrenergic, cholinergic, serotonergic and opiate transmissions are involved in the anxiolytic action of Ucn 3.