M40 acetate is a potent, non-selective galanin receptor antagonist (Ki values are 1.82 and 5.1 nM at GAL1 and GAL2 respectively) that inhibits galanin (1-29) binding in rat brain in vitro (IC50 = 3 - 15 nM). Attenuates the antidepressant effects of fluoxetine and blocks galanin-induced food intake in vivo. Also exhibits weak partial agonist activity at peripheral GAL2 receptors at doses > 100 nM.