Biochemical, cellular and pharmacological activities of a human neuropeptide FF-related peptide

We report on the biochemical, cellular and pharmacological activities of SQA-neuropeptide FF (Ser-Gln-Ala-Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2), a peptide sequence contained in the human neuropeptide FF (neuropeptide FF, Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2) precursor. Quantitative autoradiography revealed that, in the superficial layers of the rat spinal cord, SQA-neuropeptide FF displayed the same high affinity for [I-125]1DMe ([I-125]D-Tyr-Leu-(NMe)Phe-Gln-Pro-Gln-Arg-Phe-NH2) binding sites (K-i = 0.33 nM) as did neuropeptide FF (K-i = 0.38 nM). Ln acutely dissociated mouse dorsal root ganglion neurones, SQA-neuropeptide FF reduced by 40% the depolarisation-induced rise in intracellular Ca2+ as measured with the Ca2+ indicator, Fluo-3. in mice, 1DMe and SQA-neuropeptide FF dose-dependently inhibited the antinociceptive effect of intracerebroventricular (i.c.v.) injections of morphine, but SQA-neuropeptide FF was less potent than 1DMe. Furthermore, SQA-neuropeptide FF, as well as 1DMe, produced marked hypothermia following third ventricle injections in mice. These data demonstrate that the human peptide, SQA-neuropeptide FF, exhibits biochemical and pharmacological properties similar to those of neuropeptide FF or neuropeptide FF analogues, and belongs to the neuropeptide FF family. (C) 1998 Elsevier Science B.V. All rights reserved.