Neuropeptide / Reference Research Peptides Guide

This guide covers 4 research peptides in the Neuropeptide / Reference category. Each compound is evaluated on its evidence base, mechanism, safety profile, and current clinical status.

Substance P is an 11-amino-acid neuropeptide (sequence: Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2, MW ~1347.6 g/mol) that plays a pivotal role in the central and peripheral nervous systems. As a key neurotransmitter and neuromodulator, it is significantly involved in processes such as pain transmission, inflammation, and the emetic response. Research indicates that Substance P primarily exerts its effects through the neurokinin-1 receptor (NK1R), which has been targeted by FDA-approved antagonists like aprepitant, fosaprepitant, and netupitant for their antiemetic properties. Despite their established use in managing chemotherapy-induced nausea and vomiting, studies exploring NK1R antagonists for depression have yielded inconsistent results, highlighting the complexities of this neuropeptide's role in mood regulation. The ongoing investigation into Substance P continues to reveal its multifaceted implications in pain research and potential therapeutic applications.

Neuropeptide Y (NPY) is a 36-amino-acid peptide (MW ~4271.7 g/mol) recognized as one of the most prevalent neuropeptides in the mammalian brain. It serves as a crucial orexigenic factor, significantly influencing appetite regulation and energy balance. Beyond its role in appetite stimulation, NPY is implicated in various physiological processes including stress response, circadian rhythms, and cardiovascular function. It interacts with a family of G-protein-coupled receptors (Y1, Y2, Y4, Y5), making it a focal point for research into obesity, anxiety, and epilepsy. While numerous studies have investigated NPY receptor agonists and antagonists, none have yet received regulatory approval, emphasizing the need for further exploration into its therapeutic potential. The extensive distribution and functional diversity of NPY underscore its importance as both an endogenous reference molecule and a promising target for drug development in various neurobiological contexts.

Vasoactive Intestinal Peptide (VIP) is a 28-amino-acid neuropeptide (MW ~3326.8 g/mol) that exerts significant effects on vascular and respiratory systems, functioning as a potent vasodilator, bronchodilator, and immunomodulator. Its widespread distribution across the central and peripheral nervous systems, lungs, and gastrointestinal tract highlights its physiological relevance. The synthetic peptide aviptadil (RLF-100) has been investigated under emergency use authorization for COVID-19-associated acute respiratory distress syndrome (ARDS), with Phase II/III trials demonstrating its potential utility in this context. However, it is important to note that aviptadil has not yet received FDA approval for any indication. Ongoing research continues to explore VIP's therapeutic applications in conditions such as pulmonary hypertension and sarcoidosis, reinforcing its significance in pulmonary and immunological studies while also emphasizing the necessity for further clinical validation.

Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) exists in two biologically active forms: PACAP-38 (38 amino acids, MW ~4534.3 g/mol) and PACAP-27 (27 amino acids). PACAP-38 is the predominant form in the brain and is recognized for its neuroprotective, neurotrophic, and immunomodulatory properties. This neuropeptide is part of the VIP/secretin/glucagon superfamily and shares considerable sequence homology with VIP. Research indicates that the PACAP/PAC1 signaling pathway is a validated target for migraine treatment, with ongoing investigations into anti-PACAP antibodies such as AMG 301/Lu AG09222 currently in Phase II trials. Furthermore, PACAP is being studied for its roles in post-traumatic stress disorder (PTSD), neurodegenerative diseases, and traumatic brain injury. Despite its promising potential, there are currently no approved therapeutics targeting PACAP, underscoring the necessity for continued research to elucidate its clinical applications.