Table 1. A summary of the pharmacology and structures of the human neuropeptides discussed in this review.

Peptide	Pharmacology	Structure
Substance P (SP)
Amino acids: 11 Discovered: 1931 Localization: Sensory nerves Related mammalian neuropeptides: Neurokinin A, neurokinin B Related non-neural peptides: Hemokinins, endokinins	Receptors: NK1, NK2, NK3 Antagonists: range of nonpeptide antagonists available for each receptor Therapeutic use: NK1 antagonist in emesis Positive results in clinical trials: NK1 antagonist in depression	Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2
α-Calcitonin gene related peptide (CGRP)
Amino acids: 37 Discovered: 1983 Related mammalian neuropeptides: βCGRP, intermedin Related non-neural peptides: Adrenomedullin, amylin	Receptors: CGRP1, CGRP2(?), AM2 (?) Antagonists: CGRP8–37 (peptide) BIBN4096BS (nonpeptide) Positive results in clinical trials: BIBN4096BS in migraine	Ala-Cys-Asp-Thr-Ala-Thr-Cys-Val-Thr-His-Arg-Leu-Ala-Gly-Leu-Leu-Ser-Arg-Ser-Gly-Gly-Val-Val-Lys-Asn-Asn-Phe-Val-Pro-Thr-Asn-Val-Gly-Ser-Lys-Ala-Phe-NH2
Neuropeptide Y (NPY)
Amino acids: 36 Discovered: 1982 Localization: Sympathetic, cholinergic, sensory, enteric and central neurons Related nonmammalian neuropeptides: PY in bony fish; NPF in D. melanogaster Related non-neural peptides: Peptide YY (PYY), PYY(3–36) and pancreatic polypeptide (PP)	Receptors: Y1, Y2, Y4, Y5 Antagonists: Y1 BIBO3304; Y2 BIIE0246; Y5 L-152,804 Positive results in clinical trials: none to date; Y1 and Y5 antagonists were ineffective against obesity; PYY(3–36) is in development as an anti-obesity agent	Tyr-Pro-Ser-Lys-Pro-Asp-Asn-Pro-Gly-Glu-Asp-Ala-Pro-Ala-Glu-Asp-Met-Ala-Arg-Tyr-Tyr-Ser-Ala-Leu-Arg-His-Tyr-Ile-Asn-Leu-Ile-Thr-Arg-Gln-Arg-Tyr-NH2