Substance P (1-9) is a nonapeptide that reduces the inactivation of substance P in the guinea-pig ileum and urinary bladder, and is responsible for various excitatory effects on central and peripheral neurons.
Broad spectrum neuropeptide inverse agonist and antagonist. Potent full inverse agonist for the ghrelin receptor (EC50 = 5.2 nM); diminishes constitutive ghrelin receptor signaling. Also antagonist at tachykinin, bradykinin, CCK and bombesin receptors. In
[Sar9]-Substance P is one of NK-1 receptor agonist. The action of SP on progesterone metabolism was mimicked by the rNK1-specific agonist [Sar-9,Met(O2)11]-SP.