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

Background: Exposure to extremely stressful events can lead to Posttraumati c stress disorder (PTSD). Due to the complexity of PTSD, animal models have been designed and advanced to address the role of psychosocial stressors i n 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 functi oning 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 th e 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 physiologi c symptoms of analgesia, cognitive deficits and hyporesponsivity of the hyp othalainic-pituitan-adrenal axis similar to those observed in human Subject s with PTSD. It is proposed that the cLH model may be a valuable tool for e xploring the role of genetic predisposition in the etiology of PTSD. (C) 20 01 Society of Biological Psychiatry.