NOS2 and Anxiety: Regarding anxiety-related behaviors, iNOS K.O. mice presented an anxiogenic-like phenotype which, different from the WT animals, was not affected by CUS exposure (Two way-ANOVA df=1,19; genotype: F=7.81, p<0.05; stress: F=1.45; interaction: F=4.52, p<0.05; Figure 4D).