To determine whether systemic or neuroinflammation represent susceptibility factors to developing PTSD, we measured pre-trauma levels of the pro-inflammatory cytokines IL-6, IL-1β, TNFα, and IFN-γ, the anti-inflammatory cytokine IL-10, and the pro-inflammatory neutrophil-attractant chemokine KC/GRO/CINC-1 in the serum and pre-frontal cortex of rats classified as Sus or Res according to the RISP model. This evidence concerns the gene IFNG and post-traumatic stress disorder.