nNOS‐CAPON blockers produce anxiolytic effects by promoting synaptogenesis in chronic stress‐induced animal models of anxiety

Background and Purpose Anxiety disorder is a common mental health disorder. However, there are few safe and fast‐acting anxiolytic drugs available that can treat anxiety disorder. We previously demonstrated that the interaction of neuronal NOS (nNOS) with its carboxy‐terminal PDZ ligand (CAPON) is involved in regulating anxiety‐related behaviours. Here, we further investigated the anxiolytic effects of nNOS–CAPON disruptors in chronic stress‐induced anxiety in animals. Experimental Approach Mice were intravenously treated with nNOS–CAPON disruptors, ZLc‐002 or Tat‐CAPON12C, at the last week of chronic mild stress (CMS) exposure. We also infused corticosterone (CORT) into the hippocampus of mice to model anxiety behaviours and also delivered ZLc‐002 or Tat‐CAPON12C on the last week of chronic CORT treatment via pre‐implanted cannula. Anxiety‐related behaviours were examined using elevated plus maze, open field, novelty‐suppressed feeding and light–dark (LD) tests. The level of nNOS–CAPON interaction was determined by co‐immunoprecipitation (CO‐IP) and proximity ligation assay (PLA). The neural mechanisms underlying the behavioural effects of nNOS–CAPON uncoupling in anxiety animal models were assessed by western blot, immunofluorescence and Golgi‐Cox staining. Key Results ZLc‐002 and Tat‐CAPON12C reversed CMS‐ or CORT‐induced anxiety‐related behaviours. ZLc‐002 and Tat‐CAPON12C increased synaptogenesis along with improved dendritic remodelling in CMS mice or CORT‐treated cultured neurons. Meanwhile, blocking nNOS–CAPON interaction significantly activated the cAMP response element‐binding protein (CREB)–brain‐derived neurotrophic factor (BDNF) pathway, which is associated with synaptic plasticity. Conclusion and Implications Collectively, these results provide evidence for the anxiolytic effects of nNOS–CAPON uncouplers and their underlying mechanisms in anxiety disorders.