This sequence is a neuropeptide encoded by the NPVF gene. The NPVF-is the endogenous ligand for FF1 receptor. NPVF mRNA was detected specifically in a region between the dorsomedial and ventromedial hypothalamic nuclei. Following intracerebral administration, NPVF-derived peptide blocks morphine-induced analgesia in both acute and inflammatory models of pain. The NPVF/FF1 system may be an important part of endogenous anti-opioid mechanism.