title: Nrf2-mediated haeme oxygenase-1 up-regulation induced by cobalt protoporphyrin has antinociceptive effects against inflammatory pain in the formalin test in mice.
abstract: This study investigated the effect of haeme oxygenase-1 (HO-1) in nociception induced by formalin injection in the mice hind paw. Intraperitoneal (i.p.) administration of cobalt protoporphyrin (CoPP, an HO-1 inducer, 5mg/kg) 24h before the test, inhibited the nociceptive response during the second phase, but not during the first phase of the formalin test. The effect of CoPP was prevented by treatment with tin protoporphyrin (SnPP, an inhibitor of HO-1 activity) administered either by i.p. (25mg/kg, 30 min before the test) or intraplantar (400 nmol/paw, 5 min before the test) routes. Human embryonic kidney (HEK) 293T cells treated with 10 microM CoPP expressed 20-fold higher HO-1 levels when compared to controls; this effect was suppressed by transfection with the dominant negative for the nuclear factor-erythroid 2-related factor 2 (Nrf2). Western blot analysis also revealed that CoPP treatment induced a similar 20-fold increase in HO-1 expression in the paw; this effect was attenuated in knockout mice for Nrf2. CoPP treatment of wild-type, but not in Nrf2 knockout mice, resulted in a striking increase of HO-1 stained cells surrounding the muscular tissues of the hind limbs. HO-1 positive cells were scarce in wild-type and in Nrf2 knockout untreated mice. CoPP-induced HO-1 expression in Nrf2 knockout mice was lost and correlated with the loss of antinociceptive effects. In conclusion, Nrf2-mediated HO-1 expression induced an antinociceptive effect at peripheral sites. These results suggest that HO-1 modulates the inflammatory pain pathways. Hence, the development of drugs that could raise peripheral HO-1 could be relevant in inflammatory pain treatment.
authors.affiliation: Departamento de Farmacología y Terapéutica, Facultad de Medicina, Universidad Autónoma de Madrid, Arzobispo Morcillo, 4. 28029 Madrid, Spain Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de Madrid, Spain Servicio de Farmacología Clínica and Instituto Universitario de Investigación Gerontológica y Metabólica, Hospital Universitario de la Princesa, Madrid, Spain.
authors.forename: Angelo O
authors.initials: AO
authors.lastname: Rosa
authors.forename: Javier
authors.initials: J
authors.lastname: Egea
authors.forename: Silvia
authors.initials: S
authors.lastname: Lorrio
authors.forename: Ana I
authors.initials: AI
authors.lastname: Rojo
authors.forename: Antonio
authors.initials: A
authors.lastname: Cuadrado
authors.forename: Manuela G
authors.initials: MG
authors.lastname: López
mesh_terms: D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005528:Foot / Q000294:innervation / Q000503:physiopathology; D051547:Heme Oxygenase-1 / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008665:Metalloporphyrins / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism*; D009619:Nociceptors / Q000187:drug effects / Q000378:metabolism; D010146:Pain / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D010147:Pain Measurement / Q000187:drug effects; D011524:Protoporphyrins / Q000494:pharmacology*; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000378:metabolism; D016896:Treatment Outcome; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
chemical_list: D000700:Analgesics; D000893:Anti-Inflammatory Agents; D004791:Enzyme Inhibitors; D008665:Metalloporphyrins; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D011524:Protoporphyrins; C007095:cobaltiprotoporphyrin; C032628:tin protoporphyrin IX; D051547:Heme Oxygenase-1