Effects of NO Donors and Inhibitors of NO Synthase and Guanylate Cyclase on the Acquisition of a Conditioned Defense Food Aversion Response in Edible Snails.

Experiments on edible snails revealed that NO synthase blockade with a nonspecific neuronal NO synthase inhibitor L-NAME before defense food aversion conditioning is followed by a decrease in the rate of learning. Exogenous NO donors, sodium nitroprusside and dinitrosyl iron complex, were shown to improve learning. Chronic administration of a specific soluble guanylate cyclase inhibitor ODQ also increased the rate of learning. Our results indicate that NO has a modulatory effect on the formation of a conditioned response in this type of learning.