CPEB3 and post-traumatic stress disorder: Interestingly, they also found that traumatic intensity-dependent PTSD-like fear memories occurred in CPEB3-KO mice and that hippocampal BDNF downregulation was associated with increased levels of GR during fear extinction in the CPEB3-KO animals, suggesting a possible role of GR-BDNF signaling in fear extinction [58].