Substance P is tachykinin neuropeptide that selectively binds to neurokinin 1 (NK1) receptors (Kis = 0.14 and 300 nM for NK1 and NK3, respectively) and has diverse biological activities.1,2 It is an endogenous peptide expressed in the central and peripheral nervous systems, including the enteric nervous system and in immune cells.2 Substance P is released with other neurotransmitters in the dorsal horn of the spinal cord following noxious peripheral stimulation and induces pain through NK1 receptors.3 The NK1 receptor is internalized following substance P binding, and in a rat hindpaw model of inflammation it is internalized in a greater number of spinal cord neurons following a mechanical or non-noxious stimuli, indicating a role for substance P in inflammation and hyperalgesia.4 Substance P is also involved in depression, anxiety, seizures, and emesis among other functions.2
1.Gether, U., Johansen, T.E., Snider, R.M., et al.Different binding epitopes on the NK1 receptor for substance P and non-peptide antagonistNature362(6418)345-348(1993) 2.Mu?oz, M., and Cove?as, R.Involvement of substance P and the NK-1 receptor in human pathologyAmino Acids46(7)1727-1750(2014) 3.Mantyh, P.H.Neurobiology of substance P and the NK1 receptorJ. Clin. Psychiatry63(Suppl 11)6-10(2002) 4.Abbadie, C., Trafton, J., Mantyh, P.W., et al.Inflammation increases the distribution of dorsal horn neurons that internalize the neurokinin-1 receptor in response to noxious and non-noxious stimulationJ. Neurosci.17(20)8049-8060(1997)