Receptor for NPAF (A-18-F-amide) and NPFF (F-8-F-amide) neuropeptides, also known as morphine-modulating peptides. Can also be activated by a variety of naturally occurring or synthetic FMRF-amide like ligands. This receptor mediates its action by association with G proteins that activate a phosphatidylinositol-calcium second messenger system. Expressed at high levels in the hypothalamus. Moderate levels found in the midbrain, thalamus, medulla oblongata, testis, eye, whole brain, cerebral cortex, striatum, hippocampus, cerebellum, optic nerve, placenta, spinal cord, pituitary gland and ovary. Belongs to the G-protein coupled receptor 1 family.