Stress can also downregulate neuropeptides like Met-Enkephalin-Arg-Phe, Met-Enkephalin-Arg-Gly-Leu, peptide PHI-27, somatostatin-28 (AA1-12), and little SAAS in the PFC; as the regulation of neuropeptides is brain region specific, it may be related to depression-related behaviors [91]. The gene discussed is POMC; the disease is major depressive disorder.