Tachykinin receptors are G protein-coupled receptors that mediate the effects of tachykinins, a family of neuropeptides including substance P, neurokinin A, and neurokinin B, in various physiological processes such as pain transmission, inflammation, and stress response. These receptors, primarily NK1, NK2, and NK3, are distributed throughout the central and peripheral nervous systems, playing critical roles in neuromodulation and therapeutic targets for conditions like depression and chronic pain.