The aim of this study was to investigate whether endoplasmic reticulum-related pathway is involved in single-prolonged stress (SPS) induced apoptosis in the mPFC of PTSD rats by examining the expression levels of ATF6 alpha (ATF6α), two important downstream molecular chaperones of ATF6α in the ER stress: Glucose-regulated protein (GRP) 78 and ERP57, and apoptotic factors caspase 12, caspase 9, and caspase 3.