PPARA and post-traumatic stress disorder: Importantly, as in PTSD subjects, SI mice show altered neurosteroid biosynthesis, including levels of allopregnanolone (Allo) and its isomer pregnanolone, two potent, positive, allosteric modulators of GABA action at the GABAA receptor, associated with decreased peroxisome proliferator-activated receptor (PPAR)-α protein expression [15].