About TAC / Tachykinin:
Tachykinins are a family of peptides that have been found to play an essential role in the regulation of inflammation and pain. Tachykinin is secreted when the tissue is damaged and causes vasoconstriction, bronchodilation, decreased vascular permeability and increased blood flow to the site. The word "tachykinin" comes from tachys, meaning "quickly" or "rapid," with kinin referring to kallikrein, which was historically used as a treatment for hemophilia.
The function of tachykinins lies in their ability to stimulate ciliary activity and increase mucus production, both essential functions for fighting infection. They also activate pain receptors in our sensory neurons and help facilitate the release of neurotransmitters, which can cause a decrease in pain.
Tachykinins are made up of various amino acid chains that are processed by removing dipeptides at specific points to make them into active peptide hormones. They have a high level of homology with other neuroactive substances such as substance P and neuromedin N, both responsible for triggering nausea or vomiting when they act on serotonin receptors. There is also a strong correlation between tachykinins and dopamine (DA) activity. DA is released from tachykinin-activated sensory nerves, causing increased locomotion while blocking these same molecules results in decreased locomotor behaviour due to an inability to experience pleasure.
The known members of the Tachykinin family are Substance P, neurokinin A (NKA), and neurokinin B (NKB). Substance P is the most studied and well-documented tachykinin in humans, but peptides from all three members are found to be active. It is believed that they are all derived from a common ancestral gene and share an evolutionary history. NKA is found to be most responsible for modulating the cardiovascular system, while NKB is associated with regulating smooth muscle tone in the gut and other organs.