Crypteins derived from the mouse neuropeptide FF (NPFF)A precursor display NPFF-like effects in nociceptive tests in mice

► Two new peptides derived from mouse pro-NPFFA (crypteins) were synthesized. ► Effects of crypteins were compared with NPFF in the hot-plate and tail-immersion tests in mice. ► Both crypteins, similarly to NPFF, inhibited morphine-induced antinociception. ► Anti-opioid effects of crypteins were inhibited by NPFF receptors antagonist, RF9. ► Both crypteins derived from mouse NPFFA exert NPFF-like effects.