Genetic predisposition and the development of Posttraumatic stress disorder in an animal model

Background: Exposure to extremely stressful events can lead to Posttraumatic stress disorder (PTSD). Due to the complexity of PTSD, animal models have been designed and advanced to address the role of psychosocial stressors in the etiology; however, the apparent role of genetics in susceptibility to PTSD-like behaviors in animals remains unexplored. Methods: An animal model of congenital learned helpless (cLH) behavior has been used to study the effects of genetic disposition as a risk factor for the development of PTSD-like behaviors. Animals were monitored for changes in pain tolerance, spatial memory and hypothalamic-pituitary-adrenal functioning after re-exposure to intermittent stress in the presence and absence of situational cues. Results: Exposure to stress resulted in an increase in pain tolerance in the cLH animals. In the spatial memory test 80% of the cLH animals manifested a decrease in performance after exposure to stress. These animals also had a blunted poststress corticosterone response. Conclusions: The genetic learned helpless animal model exhibited physiologic symptoms of analgesia, cognitive deficits and hyporesponsivity of the hypothalainic-pituitan-adrenal axis similar to those observed in human Subjects with PTSD. It is proposed that the cLH model may be a valuable tool for exploring the role of genetic predisposition in the etiology of PTSD. (C) 2001 Society of Biological Psychiatry.