Galanin receptor antagonist M40 blocks galanin-induced choice accuracy deficits on a delayed-nonmatching-to-position task.

Galanin is a 29-amino acid neuropeptide that coexists with acetylcholine in the medial septum/diagonal band in the rat and impairs choice accuracy on an operant delayed-nonmatching-to-position (DNMTP) working-memory task. M40, a peptidergic galanin antagonist, has previously been shown to block several physiological actions of galanin. The present experiments tested the ability of M40 to block the effects of galanin on DNMTP performance. M40 completely blocked choice-accuracy deficits induced by galanin administration in both the lateral ventricle and ventral hippocampus, at doses of M40 approximately 5-fold the molar dose of galanin. M40 appears to be an effective galanin antagonist in a rodent memory paradigm, indicating that this compound may prove useful in investigating the role of endogenous galanin in learning and memory.