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Spacefilling model of substance P
tachykinin, precursor 1
Identifiers
Symbol	TAC1 TAC2, NKNA
HUGO	11517
Entrez	6863
OMIM	162320
RefSeq	NM_003182
UniProt	P20366
Other data
Locus	Chr. 7 q21-q22

tachykinin receptor 1
Identifiers
Symbol	TACR1 TAC1R
HUGO	11526
Entrez	6869
OMIM	162323
RefSeq	NM_001058
UniProt	P25103
Other data
Locus	Chr. 2 p13.1-p12

In neuroscience, Substance P is a neuropeptide: a short-chain polypeptide that functions as a neurotransmitter and as a neuromodulator. It belongs to the tachykinin neuropeptide family.

Substance P is an 11-amino acid polypeptide with the sequence: Arg Pro Lys Pro Gln Gln Phe Phe Gly Leu Met NH2. In the central nervous system, substance P has been associated in the regulation of mood disorders, anxiety, stress, reinforcement, neurogenesis, respiratory rhythm, neurotoxicity, nausea / emesis and pain.

It also has effects as a potent vasodilator. This is caused by the release of nitric oxide from the endothelium. Its release can cause hypotension.

The endogenous receptor for Substance P is neurokinin 1 receptor (NK1-receptor, NK1R). It belongs to the tachykinin receptor sub-family of GPCRs.

The vomiting center in the brainstem contains high concentrations of substance P and its receptor, in addition to other neurotransmitters such as choline, histamine, dopamine, serotonin, and opioids. Their activation stimulates the vomiting reflex. Different emetic pathways exist, and substance P/NK1R appears to be within the final common pathway to regulate vomiting. ^[1]

Substance P is involved in the transmission of pain impulses from peripheral receptors to the central nervous system. It has been theorized that it plays a part in fibromyalgia. Capsaicin has been shown to reduce the levels of Substance P probably by reducing the number of C-fibre nerves or causing these nerves to be more tolerant.

Substance P antagonist (SPA) aprepitant is available in the market in the treatment of chemotherapy-induced nausea / emesis.

Substance P has been shown to stimulate cellular growth in cell culture ^[2], and it was shown that Substance P could promote wound healing of non-healing ulcers in humans. ^[3] It has also been shown to reverse diabetes in mice. ^[4]

Naked Mole Rats lack Substance P and do not feel pain when painful stimuli are administered to the skin.

1. ^ Hornby PJ. Central neurocircuitry associated with emesis. Am J Med 2001;111:106S-12S
2. ^ Reid TW, Murphy C, Iwahashi C, Foster B, and Mannis M. Stimulation of epithelial cell growth by the neuropeptide substance P. J Cell Biochem 1993; 52:476-485
3. ^ Brown S, Lamberts D, Reid TW, Nishida T, Murphy C. Neurophilic and Anhidrotric Keratopathy Treated with Substance P and Insulinlike Growth Factor 1. Arch Ophthalmol 1997; 115:926-927
4. ^ http://www.newscientist.com/article/dn10812-breakthrough-sheds-light-on-cause-of-diabetes.html

• http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=36511 Substance P in PubChem