Astrocytes contain a functional urea cycle, where the enzyme ornithine decarboxylase 1 (ODC1) converts ornithine into putrescine, providing a precursor for MAOB-dependent GABA.30,33 Inhibition of ODC1 could block putrescine production, thereby reducing GABA synthesis and restoring inhibitory balance, suggesting another potent therapeutic strategy for PTSD. This evidence concerns the gene ODC1 and post-traumatic stress disorder.