Animal models are indispensable tools in the search to identify new antidepressant drugs and to provide insights into the neuropathology that underlies the idiopathic disease state of depression. Various paradigms have been developed and are instrumental in detecting the antidepressant-like potential of novel compounds in preclinical settings. The models commonly used are diverse and were developed originally based on the behavioral consequences of stress, drug, lesion or genetic manipulation. As new targets are developed, both serendipitous and through hypothesis-driven research, existing...