CRH and Anxiety: The amygdala CRH system plays a critical role in mediating anxiety behavior (Schulkin, 2006) and here the anxious phenotype in F2 PNS males was associated with significantly greater Crh mRNA expression in the central amygdala, consistent with findings in F1 PNS rats that also exhibit increased anxiety-related behaviors (Brunton and Russell, 2010, Cratty et al., 1995, Zohar and Weinstock, 2011).