MAOB and post-traumatic stress disorder: 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.