Animal models of depression and neuroplasticity: assessing drug action in relation to behavior and neurogenesis.

Depression is among the most prevalent forms of mental illness and a major cause of morbidity worldwide. Diagnosis of depression is mainly based on symptomatic criteria, and the heterogeneity of the disease suggests that multiple different biological mechanisms may underlie its etiology. Animal models have been important for recent advances in experimental neuroscience, including modeling of human mood disorders, such as depression and anxiety. Over the past few decades, a number of stress and neurobiochemical models have been developed as primary efficacy measures in depression trials, which are paving the way for the discovery of novel therapeutic targets. Recent data indicates that stress-related mood disorders have influence on neuroplasticity and adult neurogenesis. In this chapter, several currently available animal models are presented as powerful tools for both mechanistic studies into the neurobiology of the antidepressant response and for drug discovery.