Animal models of anxiety: a comprehensive review.

Animal models can be used to contribute to understanding the information about molecular mechanisms involved in anxiety and for screening and developing new medications for their treatment that would be impossible in humans. The human studies have established the genetic basis of anxiety and animal studies have been used to attempt to further clarify its genetic determinants. In the field of anxiety research, animal models can be grouped into two main classes. The first involves the animal's conditioned responses to stressful and often painful events (e.g. exposure to electric foot shock) and the second includes ethologically based paradigms and involves the animal's spontaneous or natural reactions (e.g. flight, avoidance and freezing) to stress stimuli that do not explicitly involve pain or discomfort (e.g. exposure to a novel highly illuminated test chamber or to a predator). The current review enlightens the various aspects of animal model of anxiety, which may be used for research purpose.