title: Sex differences in the effects of neuropeptide FF and IgG from neuropeptide FF on morphine- and stress-induced analgesia.
abstract: There is evidence suggesting that the endogenous mammalian octapeptide FLFQPQRFamide (F8Fa or neuropeptide FF, NPFF) has modulatory effects on opioid-mediated analgesia in rodents. There is also substantial evidence for sex differences in opioid analgesia, whereby male rats and mice display greater levels of opioid-mediated analgesia than females. In the present study, determinations were made of the effects of NPFF and IgG from antiserum against NPFF on morphine- and restraint stress-induced opioid analgesia in male and female deer mice. Intracerebroventricular (ICV) administrations of NPFF (0.10-10 micrograms) reduced in a dose-dependent manner morphine- and stress-induced analgesia in both male and female mice, with NPFF having markedly greater antagonistic effects in the male than female mice. Additionally, ICV administrations of NPFF-IgG increased the levels of morphine- and stress-induced analgesia and significantly reduced basal nociceptive sensitivity in male mice, whereas, in female mice, NPFF-IgG had no significant effects on either opioid-mediated analgesia or nociceptive sensitivity. These results indicate that there are sex differences in the modulatory effects of NPFF on opioid-mediated analgesia.
authors.affiliation: Division of Oral Biology, Faculty of Dentistry, University of Western Ontario, London, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Kavaliers
authors.forename: D
authors.initials: D
authors.lastname: Innes
mesh_terms: D000698:Analgesia; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D007074:Immunoglobulin G; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D009842:Oligopeptides / Q000276:immunology / Q000494:pharmacology*; D010146:Pain / Q000378:metabolism*; D010542:Peromyscus; D012727:Sex Characteristics; D013315:Stress, Psychological / Q000150:complications
chemical_list: D007074:Immunoglobulin G; D009842:Oligopeptides; D009020:Morphine; C053651:phenylalanyl-leucyl-phenylalanyl-glutaminyl-prolyl-glutaminyl-arginyl-phenylalaninamide