TAC1 and post-traumatic stress disorder: In addition to chronic SDS, a recent study using a SEFL paradigm that mimics the development of a persistent traumatic memory showed unique molecular changes in stress-susceptible males, distinct from their stress-resilient male counterparts.25 Epigenetic profiling revealed differential expressions between susceptible and resilient animals in PTSD-linked genes, including Adcyap1, Bdnf, Drd2, and novel targets, such as tachykinin receptor 1 (tacr1, a receptor that binds to the neuropeptide substance P), which may contribute to stress responses yet remain underexplored in PTSD.25