NPY and post-traumatic stress disorder: Consistent with these findings, decreased NPY in selected brain regions has been found in several models of dysregulated emotionality and stress, such as learned helplessness (125), maternal separation/deprivation (126, 127), chronic mild stress (128), social isolation (129), PTSD (79), and acute as well as early-life stress (130, 131), as well as in animal models of alcohol use such as an alcohol-preferring rat strain (132).