HDAC9 and Anxiety: In the present experimental study, the interacting influence of ECB/TRPV1 system‐related ligands and histone deacetylase (HDAC) inhibitors, which induce histone acetylation, on the NC‐ and/or stressor‐induced anxiety‐ and working memory‐related behaviours, is evaluated, and therapeutic importance of the mutual control of the ECB/TRPV1 systems and epigenetic processes is discussed.