γ-Neuropeptide is an endogenous tachykinin/neurokinin peptide that binds neurokinin (NK) receptors, displaying some selectivity for NK2 isoforms. This peptide mediates hypothalamic-pituitary-adrenal (HPA) axis signaling and reproductive hormone release, inhibiting hypothalamic secretion of luteinizing hormone (LH). Additionally, γ-neuropeptide induces vasodilation and hypotensive activity in vivo. γ-Neuropeptide may play a role in gastrointestinal motility, as it stimulates smooth muscle contraction in the gastrointestinal tract; it also stimulates smooth muscle contraction in the respiratory tract. γ-Neuropeptide forms complexes with Cu(II) as well.