HTR1A and Anxiety: Neuronal nitric oxide synthase (nNOS) is enriched in the hippocampus.16 Our previous study revealed that chronic stress upregulates the level and activity of hippocampal nNOS and thus contributes to stress‐induced depressive behaviors.17 There are some reports that nNOS inhibitors produce anxiolytic‐like effects, and 5‐HT system is dysfunctional in nNOS knockout mice.18, 19, 20 However, it remains unknown whether nNOS‐NO pathway contributes to 5‐HT1A receptor deficiency in the development of anxiety.