A novel 26RFa peptide containing both analgesic and anti-inflammatory functions from Chinese tree shrew

26RFa is one of neuroendocrine peptide groups in the RFamide peptide family containing conserved Arg-Phe/Tyr-NH2 motif at their C-terminus. They exert multiple biological functions in vertebrates. A novel 26RFa peptide (TC26RFa) with unique structure is identified from the tree shrew of Tupaia belangeri chinensis in the present study. In structure, different from other 26RFa peptides containing conserved Phe-Arg-Phe-NH2 motif at their C-terminus, there is a Phe-Arg-Tyr-NH2 C-terminus in TC26RFa. It has been found that TC26RFa of intraperitoneal injection exerts strong analgesic activities in several mice models including acetic acid-induced abdominal writhing, formalin-induced paw licking, and thermal pain-induced tail withdrawal. It shows comparable analgesic ability with morphine. In addition, this peptide has been found to inhibit inflammatory factor secretion (including tumor necrosis factor-α, interleukin-6, and interleukin-1β) induced by lipopolysaccharides (LPS). Furthermore, it stimulates secretion of the anti-inflammatory factor, interleukin-10. In addition to the identification of a novel 26RFa peptide from tree shrew, a new type of function (anti-inflammation) involved in 26RFa peptide is discovered.