Tachykinins are active peptides which excite neurons, evoke behavioral responses, are potent vasodilators and secretagogues, and contract (directly or indirectly) many smooth muscles. Tachykinins (TK) are expressed throughout the nervous system. APMGFQGMR-amide is also expressed in the retrocerebral complex (at protein level). APMGFQGMR-amide. TIMGFQGMR-amide. SPFRYFEMR-amide. NPRWELRGMFVGVR-amide. Belongs to the tachykinin family.