Neurokinin A

Inflammation / GI / Respiratory

Also known as: NKA, Substance K, Neurokinin-A, Neuromedin L, TAC1

TachykininsResearch phase: Endogenous peptide (well characterized)Regulatory: Endogenous peptide. NK2R antagonists have been explored clinically but none are approved.

Mechanism

Neurokinin A is a tachykinin peptide closely related to Substance P, both encoded by the same TAC1 gene. It preferentially activates NK2 receptors on smooth muscle, causing bronchoconstriction in the airways and contraction in the GI tract. It plays roles in asthma, inflammatory bowel disease, and pain signaling.

Technical detail

Neurokinin A (His-Lys-Thr-Asp-Ser-Phe-Val-Gly-Leu-Met-NH2) is a 10-amino-acid tachykinin peptide derived from the TAC1 gene (alternate splicing of the same gene encoding substance P). It preferentially binds NK2R (Gq-coupled) on smooth muscle, activating PLC-IP3-DAG signaling for contraction. In airways, NKA is a more potent bronchoconstrictor than substance P. In the GI tract, it contracts circular smooth muscle (peristalsis). NK2R antagonists have been explored for asthma and IBS but none have reached approval. NKA is released from sensory C-fibers alongside substance P during neurogenic inflammation.

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