International Journal of Comparative Psychology

Chronically elevated levels of corticotropin-releasing hormone (CRH) are implicated in human stress-related and affective disorders, including generalized anxiety disorder and major depression. To gain more insight into the relationship between hyperactivity of the CRH system and associated neuroendocrine, autonomic, physiological, and behavioral changes, we have developed a transgenic mouse model of CRH overproduction (CRHOE). In this study, we explored the behavioral consequences of chronic CRH overproduction in mice of the two available transgenic lines (CRH-OE2122 and CRH-OE2123) in paradigms measuring behavioral aspects of stress, anxiety, and depression. These paradigms include tasks based on free exploration of novel environments (unfamiliar homecage and unfamiliar open field), stress-induced hyperthermia, tests associated with anxiety- related behavior (elevated plus maze and light-dark box), and paradigms in which (anti-)depressant-like behaviors can be detected (tail suspension test and forced swim test). The only relatively consistent finding, although not always significant, was reduced locomotor activity in CRH-OE2122 mice, corresponding well with the known effects of CRH on locomotion. Contrary to our predictions, CRH-OE mice did not show an altered response to stress, and a phenotype indicative of increased anxiety and/or depression was not evident in CRH-OE mice.