TH and Anxiety: For example, a previous study showed that male prairie voles exposed to 6 weeks of isolation after weaning display increased anxiety-like behaviors and altered mRNA levels for OT, vasopressin (AVP), corticotrophin releasing hormone (CRH), and tyrosine hydroxylase (TH) in the PVN (Pan et al., 2009), suggesting that post-weaning isolation can alter a wide variety of neurochemical systems in prairie voles.