A method of treating neuropathic pain in a subject, the method comprising administering to a subject a therapeutically effective amount of a peptide of formula (I) or (II), or a pharmaceutically acceptable salt thereof: R1-CRSVEGSCG-R2 (I) (SEQ ID NO:1) wherein R1 is selected from the group consisting of YLRIVQ, LRIVQ, RIVQ, IVQ, VQ, and Q, or R is absent; and R2 is F (phenylalanine) or R2 is absent. R1-CRRFVESSC-R2 (II) (SEQ ID NO:6) wherein R1 is selected from the group consisting of YLRVMIK, LRVMK, RVMK, VMK, MK, and K, or R1 is absent; and R2 is selected from the group consisting of A (alanine) and AF (alanine-phenylalanine), or R2 is absent.