Urocortin 3 administration impairs fear motivated learning in mice is mediated by transmitters.

Urocortin 3 (Ucn 3) was found to impair passive avoidance learning in male and female mice. The possible involvement of transmitters in the action, the animals were pretreated with the following receptor antagonists in doses which alone could not influence the measurement. Haloperidol (a D2, dopamine receptor antagonist), phenoxybenzamine (a nonselective α1-adrenergic receptor antagonist), atropine (a nonselective muscarinic acetylcholine receptor antagonist), bicuculline (a γ-aminobutyric acid subunit A receptor antagonist), nitro-L-arginine (a nitric oxide synthase inhibitor), antalarmin (a CRF1 receptor antagonist) and astressin 2B (a CRF2 receptor antagonist). Haloperidol, phenoxybenzamine, bicuculline, atropine, nitro-L-arginine and astressin 2B prevented the action of Ucn 3, in both sexes, whereas antalarmin exerted no action in either male or female animals.