Neuronal nitric-oxide synthase deficiency impairs the long-term memory of olfactory fear learning and increases odor generalization

Pretraining nNOS blocker L-NAME in wild-type mice reduces freezing responses during an odor cued test. Mice received D-NAME (white bar) or L-NAME injections 20 min before the training with odor and foot shock. (A) Mean time spent freezing across the trained odor for each group 24 h and (B) 7 d after the training. The higher doses of L-NAME significantly decreases the amount of freezing to the odor during the odor test. (*) Significant difference from the control D-NAME group, P < 0.05