The peptide NDP-MSH induces phenotype changes in the heart that resemble ischemic preconditioning Anna Catania a, *, Caterina Lonati a , Andrea Sordi a , Patrizia Leonardi a,b , Andrea Carlin a,b , Stefano Gatti c a Center for Preclinical Investigation, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milano, Italy b Department of Internal Medicine, Universita ` degli Studi di Milano, Milano, Italy c Center for Surgical Research, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Milano, Italy 1. Introduction Corticotropin (ACTH) and a-, b-, and g-melanocyte-stimulating hormones (a-, b-, g-MSH), collectively called melanocortin peptides, exert multiple effects on the host [7]. These ancient modulatory peptides derived from pro-opiomelanocortin (POMC) operate to protect cells from injury caused by inflammatory mediators, pathogens, ultraviolet light, and other stimuli [8]. The capacity of melanocortins to reduce activation of the nuclear transcription factor NF-kB during acute injury is certainly critical in tissue protection [30,35,43]. Experiments on different cell types and tissues showed that phosphorylation of the inhibitory protein IkBa induced by cytokines, bacterial products, and viruses was inhibited by melanocortins [6]. Previous research showed that a-MSH and synthetic melano- cortin agonists exert protective effects on the heart in experi- mental models of myocardial damage including ischemia and reperfusion injury (RI) [3,21,25,46,54] and transplantation [12,13,20]. In these experiments, treatment efficacy was demon- strated by reduced harmful mediator production and diminished tissue damage during ischemia or at the time of reperfusion. In the present research we tested the idea that melanocortin treatment could induce specific changes in the resting heart, changes that could prevent damage from a subsequent injury. There is great interest in development of drugs that can limit cardiac damage caused by myocardial infarction or surgical procedures. The discovery of ischemic preconditioning, a potent cardioprotective mechanism induced by repetitive sublethal ischemic events [48], encouraged the search for pharmacological agents that mimic this effect [55]. Indeed, ischemic precondition- ing represents the most effective and consistently reproducible Peptides 31 (2010) 116–122 ARTICLE INFO Article history: Received 11 September 2009 Received in revised form 23 September 2009 Accepted 23 September 2009 Available online 30 September 2009 Keywords: a-Melanocyte-stimulating hormone (a- MSH) Nle 4 ,DPhe 7 -a-MSH (NDP-MSH) melanocortin 1 receptor (MC1R) Reperfusion injury Ischemic preconditioning Signal transducer and activator of transcription (STAT)3 Interleukin 6 (IL-6) Suppressor of cytokine signaling (SOCS)3 Nur77 ABSTRACT a-Melanocyte-stimulating hormone (a-MSH) is a pro-opiomelanocortin (POMC)-derived peptide that exerts multiple protective effects on host cells. Previous investigations showed that treatment with a- MSH or synthetic melanocortin agonists reduces heart damage in reperfusion injury and transplantation. The aim of this preclinical research was to determine whether melanocortin treatment induces preconditioning-like cardioprotection. In particular, the plan was to assess whether melanocortin administration causes phenotype changes similar to those induced by repetitive ischemic events. The idea was conceived because both ischemic preconditioning and melanocortin signaling largely depend on cAMP response element binding protein (CREB) phosphorylation. Rats received single i.v. injections of 750 mg/kg of the a-MSH analogue Nle 4 ,DPhe 7 -a-MSH (NDP-MSH) or saline and were sacrificed at 0.5, 1, 3, or 5 h. Western blot analysis showed that rat hearts expressed melanocortin 1 receptor (MC1R) protein. Treatment with NDP-MSH was associated with early and marked increase in interleukin 6 (IL-6) mRNA. This was followed by signal transducer and activator of transcription 3 (STAT3) phosphorylation and induction of suppressor of cytokine signaling 3 (SOCS3). There were no changes in expression of other cytokines of the IL-6 family. Expression of IL-10, IL-1b, and TNF-a was likewise unaltered. In hearts of rats treated with NDP-MSH there was increased expression of the orphan nuclear receptor Nur77. The data indicate that NDP-MSH induces phenotype changes that closely resemble ischemic preconditioning and likely contribute to its established protection against reperfusion injury. In addition, the increased expression of Nur77 and SOCS3 could be part of a broader anti-inflammatory effect. ß 2009 Elsevier Inc. All rights reserved. * Corresponding author at: Centro di Sperimentazione Preclinica, Padiglione Granelli, Fondazione IRCCS Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena, Via F. Sforza 35, Milano 20122, Italy. Tel.: +39 02 5503 3318; fax: +39 02 5503 3318. E-mail address: anna.catania@unimi.it (A. Catania). Contents lists available at ScienceDirect Peptides journal homepage: www.elsevier.com/locate/peptides 0196-9781/$ – see front matter ß 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.peptides.2009.09.030