Tachykinins are active peptides which excite neurons, evoke behavioral responses, are potent vasodilators and secretagogues, and contract (directly or indirectly) many smooth muscles. Endokinin-A induces thermal hyperalgesia and pain-related behavior such as scratching following intrathecal administration in rats. These effects are suppressed by treatment with endokinin-C. Endokinin-A/B reduces arterial blood pressure and increases sperm motility. {ECO:0000269|PubMed:12716968, ECO:0000269|PubMed:17101218, ECO:0000269|PubMed:17437961, ECO:0000269|PubMed:17655832}. This is the function of TAC4 (tachykinin precursor 4, ENSG00000176358).