HDAC9 and psychosocial stress measurement: Although the contribution of histone acetylation to the modulated function of the direct NC target nAChRs has not been fully elucidated, reduced histone acetylation at the promoters of the gene encoding the acetylcholine-hydrolyzing enzyme acetylcholinesterase (AChE), which seemed to dysregulate the function of the nicotinic cholinergic system, has been reported in the hippocampus of stressor-treated mice eliciting anxiety-like behaviors, and HDAC inhibition mediated by gene manipulation regulatorily abolished both AChE-related effects and stress-related anxiety [117].