EN
Posttraumatic stress disorder (PTSD) develops following exposure to a traumatic event, afflicting 7–12% of the population. Women are shown to be twice as likely as men to develop PTSD. Moreover, their susceptibility to PTSD following a trauma depending on the phase of menstrual cycle. Clarification of the biological mechanism underlying sex differences in the susceptibility to PTSD is necessary to design sexspecific therapies. We addressed this issue using an animal model of extinction and renewal of conditioned fear. We investigated the impact of estrus cycle phase on fear memory acquisition, extinction and recall. We hypothesized that hormonal status would influence memory formation and recall at all stages of the behavioral procedure. Therefore we employed a matrix design, carrying out fear conditioning, extinction and fear/extinction memory recall in either estrus or metaestrus. Males and gonadectomized have been trained at corresponding time intervals While estrus cycle phase during fear conditioning did not affect the retrieval of fear memory, hormonal status during both extinction and following fear/extinction memory recall affected animals’ freezing rates. Highest differences have been found in animals that have been tested in metaestrus and extinguished in estrus or metaestrus. Collectively, we claim that it is necessary to control the hormonal status of female animals used in experiments involving fear conditioning, extinction and renewal.