Tonic LC firing is increased in WKY rats as compared to non-depressive-like Wistar and Sprague Dawley rats (Bruzos-Cidon et al., 2014) and although NPY levels in the LC have not been assessed, plasma levels of NPY are three time lower in WKY rats as compared to Sprague Dawley rats (Myers et al., 1993). Furthermore, it has been established that NPY and NPY receptor mRNA is downregulated in the hippocampus and hypothalamus of rats and tree shrews following social defeat stress, although this study BTK inhibitor in vitro did not address differences in coping

responses (Zambello et al., 2010). Since NPY has been established as an “anti-stress” neuropeptide studies have begun evaluating individual differences in NPY levels within susceptible and resilient populations of rats from the same strain. Decreased NPY levels were reported in the amygdala, hippocampus and periaqueductal gray of rats that were vulnerable to a predator-scent stress paradigm compared with

the resilient phenotype (Cohen et al., 2012). In addition, NPY mRNA in the amygdala was negatively correlated with anxious behavior in rats characterized as exhibiting high or low levels of anxiety (Primeaux et al., 2006). Future studies in rodents capable of evaluating the impact of coping strategy on NPY levels follow social stress will be an important advancement in understanding Entinostat the role of NPY in stress resilience. Notably, preclinical data linking NPY to resilience are relevant to findings in humans; deficiencies within the central NPY system have been demonstrated in patients with major depression (Widerlov et al., 1988). Individuals Ketanserin with combat-related PTSD also have significantly lower levels of NPY in

their cerebrospinal fluid (Rasmusson et al., 2000 and Sah et al., 2014) and NPY levels recover during remission (Yehuda et al., 2006). Similarly, elevated levels of NPY were reported in highly resilient special operations soldiers (Morgan et al., 2000). The single prolonged stress model in rodents produces many behavioral and biochemical features of PTSD (Liberzon et al., 1997) and in a recent study, intranasal NPY effectively blocked or reversed many of the stress-related consequences (Serova et al., 2014 and Serova et al., 2013). Several lines of evidence from studies in animals and humans point towards NPY in the psychobiology of resilience to stress-induced psychiatric disorders, while deficits of NPY in the brain are related to psychiatric disorders. Studies designed to evaluate NPY levels in rodents demonstrating differing coping strategies will be an important advancement in elucidating the neural basis of stress resiliency. d. Others A recent study suggests a role for Acetylcholinergic mechanisms in mediating resilience (Mineur et al., 2013).