Assessing antidepressant activity in rodents: recent developments and future needs

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. As new targets are developed, both serendipitously and through hypothesis-driven research, existing animal paradigms are being modified and new tests are being developed to detect antidepressant actions of compounds acting on a broad range of neural and genetic targets. This review focuses on recent findings regarding some of the most widely employed animal models used currently to predict antidepressant potential. Emphasis is placed on recent modifications to such paradigms that have increased their utility and reliability. Furthermore, some key issues that need to be addressed for future discovery of novel antidepressant agents are examined, and the available data on genetically altered mice that might lead to the discovery of novel targets for antidepressant action are collated.