BACKGROUND: Posttraumatic stress disorder (PTSD) is a stress disorder that develops in only some individuals following a traumatic event. Data suggest that a substantial fraction of women recover after sexual violence. Thus, the investigation of stress and antistress neuropeptides in this sample has the potential to inform the neurochemistry of resilience following trauma. Nociceptin is an antistress neuropeptide in the brain that promotes resilience in animal models of PTSD.
METHODS: [11C]NOP-1A positron emission tomography was used to measure the in vivo binding to nociceptin receptors in 18 college women who had experienced sexual violence irrespective of whether they met DSM-5 diagnostic criteria for PTSD. [11C]NOP-1A data from 18 healthy control subjects were also included to provide a contrast with the sexual violence group. [11C]NOP-1A total distribution volume (VT) in the regions of interest were measured with kinetic analysis using the arterial input function. The relationships between regional VT and Clinician-Administered PTSD Scale for DSM-5 total symptom and subscale severity were examined using correlational analyses.
RESULTS: No differences in [11C]NOP-1A VT were noted between the sexual violence and control groups. VT in the midbrain and cerebellum were positively correlated with PTSD total symptom severity in the past month before positron emission tomography. Intrusion/re-experiencing and avoidance subscale symptoms drove this relationship. Stratification of subjects by a DSM-5 PTSD diagnosis and contrasting their VT with that in control subjects showed no group differences.
CONCLUSIONS: Decreased midbrain and cerebellum nociceptin receptors are associated with less severe PTSD symptoms. Medications that target nociceptin should be explored to prevent and treat PTSD.