Animal Models for Post-Traumatic Stress Disorder

Animal models of post-traumatic stress disorder (PTSD) provide a wellspring of biological information about this complex condition by providing the opportunity to manipulate trauma exposure and measure biological outcomes in a systematic manner that is not possible in clinical studies. Symptoms of PTSD may be induced in animals by physical (immobilization, foot shock, underwater stress) and psychological stressors (exposure to predator, social defeat, early life trauma) or a combination of both. In addition, genetic, epigenetic and transgenic models have been created by breeding animals with a behavioral propensity for maladaptive stress response or by directly manipulating genes that have been implicated in PTSD. The effect of stressors in animals is measured by a variety of means, including observation of behavior, measurement of structural alterations in the brain and of physiological markers such as HPA axis activity and altered gene expression of central nervous system neurotransmitter system components including receptors. By comparing changes observed in stress exposed animals to humans with PTSD and by comparing animal response to treatments that are effective in humans, we can determine the validity of PTSD animal models. The identification of a reliable physiological marker of maladaptive stress response in animals as well as standard use of behavioral cutoff criteria are critical to the development of a valid animal model of PTSD.