Broad therapeutic treatment window of [Nle4, D-Phe7]α-melanocyte-stimulating hormone for long-lasting protection against ischemic stroke, in Mongolian gerbils
Introduction
Following a cerebrovascular accident, brain cell damage may occur within minutes to days and through several, perhaps parallel, mechanisms including excitotoxicity, inflammatory response and apoptosis (Choi, 1996, Dirnagl et al., 1999, Leker and Shohami, 2002). The excitatory amino acids glutamate and aspartate are released in uncontrolled manner in ischemic areas, and excitotoxicity directly and/or indirectly generates large amounts of radical species (Choi, 1996, Leker and Shohami, 2002). Neuronal and inducible nitric oxide (NO) synthases are up-regulated, and the overproduced NO reacts with oxygen species to produce highly reactive radicals, including peroxynitrite, deleterious for neuronal survival (Leker and Shohami, 2002). Proinflammatory mediators produced by the neurochemical cascade triggered by ischemia include interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α), adhesion molecules and tissue metalloproteinases (Leker and Shohami, 2002). Apoptosis may be responsible for up to 50% of cellular deaths in cerebral ischemia. The mechanisms leading to inflammatory response and apoptotic death in ischemic brain injury involve several possible pathways including a mitogen-activated protein kinase (MAPK)-dependent pathway (Beyaert et al., 1996, Herlaar and Brown, 1999, Sugino et al., 2000), a nuclear factor-kB-dependent pathway (Clemens et al., 1997), and the activation of inducible proapoptotic members of the Bcl-2 family (Choi, 1996, Matsushita et al., 1998). Besides an abundant production of proinflammatory cytokines, these pathways lead to the activation of caspases, also involved in inflammation (Schulz et al., 1999). The caspase pathway culminates in the formation of effector caspases, which in turn activate DNA breaking enzymes and energy consuming DNA repair enzymes, leading to breakdown of DNA and cell death (Choi, 1996, Ni et al., 1998, Schulz et al., 1999).
Several innovative neuroprotective approaches have been shown to reduce brain lesions in animal models of stroke (Amemiya et al., 2005, Borsello et al., 2003, Brott and Bogousslavsky, 2000, Endres et al., 2004, Leker and Shohami, 2002, Ottani et al., 2003, Sun et al., 2003, Wise et al., 2005). However, clinical trials failed to confirm animal data so far. The reasons for these disappointing results could be: presence of toxic side effects, short therapeutic treatment window and a single-mechanism neuronal damage blockade (Gladstone et al., 2002, Leker and Shohami, 2002, Wise et al., 2005).
Melanocortins are endogenous peptides of the adrenocorticotropin/melanocyte-stimulating hormone (ACTH/MSH) group. Besides a few reports on the protective effects of α-MSH in conditions of experimental brain ischemia (Huang and Tatro, 2002, Huh et al., 1997) — but not of γ2-MSH and the ACTH-(4-9) analog ORG 2766 (Herz et al., 1996, Herz et al., 1998) — it has been recently provided (Giuliani et al., 2006) the first clear evidence that [Nle4, D-Phe7] α-MSH (NDP-α-MSH), which activates melanocortin MC1, MC3, MC4 and MC5 receptor subtypes, causes a strong protection, with a therapeutic treatment window of at least 9 h, against inflammatory, apoptotic, histopathological and behavioral consequences of brain ischemia, through the activation of central nervous system (CNS) melanocortin MC4 receptors.
From a practical point of view, effective protection against ischemic stroke should be definitive, and it requires an as much as possible broad therapeutic treatment window. The aim of the present study, therefore, was to precisely identify the therapeutic treatment window of melanocortins, and to determine whether these neuropeptides chronically protect against damage consequent to transient global brain ischemia.
Section snippets
Transient global brain ischemia in gerbils
Male Mongolian gerbils (Charles River Breeding Laboratories, Calco, Como, Italy), weighing 70–80 g, were used. They were kept in air-conditioned colony rooms (temperature 21 ± 1 °C, humidity 60%) on a natural light/dark cycle, with food in pellets and tap water available ad libitum. Housing conditions and experimental procedures were in strict accordance with the European Community regulations on the use and care of animals for scientific purposes (CEE Council 89/609; Italian D.L. 22-1-92 No.
Learning and memory performance
The Mongolian gerbil is an useful laboratory animal for studying the consequences of cerebral ischemia, including the effects on learning and memory, as well as for evaluating neuroprotective drugs in ischemic stroke (Katsuta et al., 2003, Kirino, 1982, Simon et al., 1984, Wiard et al., 1995). We investigated, therefore, the ability of gerbils subjected to a 10-min period of global cerebral ischemia to learn, remember and go to the platform of Morris apparatus (Giuliani et al., 2006, Morris,
Discussion
The only approved therapy for ischemic stroke is early (within 3 h) thrombolysis with alteplase (The National Institute of Neurological Disorders and Stroke rt-PA Stroke Study Group, 1995). Because of several concomitant factors, including a narrow treatment window, no innovative drugs have been proven successful in advanced clinical trials (Gladstone et al., 2002). A recent meta-analysis suggests the time window of alteplase might be extended up to 4–5 h after stroke onset (Hacke et al., 2004
Acknowledgements
This work was supported in part by grants from Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR), Roma, and Fondazione Cassa di Risparmio di Modena, Modena, Italy.
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2022, Journal of Stroke and Cerebrovascular DiseasesNDP-α-MSH induces intense neurogenesis and cognitive recovery in Alzheimer transgenic mice through activation of melanocortin MC<inf>4</inf> receptors
2015, Molecular and Cellular NeuroscienceCitation Excerpt :Conversely, NDP-α-MSH-treated (for 50 days) Tg2576 mice displayed significantly better performance in learning and memory in all sessions of the Morris test, as compared with saline-treated control Tg2576 mice (Fig. 2A, B). Based on our previous observations, we investigated the role of melanocortin MC4 receptors mainly expressed in the CNS (Mountjoy, 2010), whose activation induced neuroprotection in acute brain injury and AD (Bitto et al., 2012; Giuliani et al., 2006a,b, 2014a,b) and promoted neurogenesis in stroke (Giuliani et al., 2011). Consistent with our previous findings, the favorable effects of NDP-α-MSH on learning and memory performance in Tg2576 mice were totally prevented by pretreatment with the selective MC4 receptor antagonist HS024 (Fig. 2A, B).
Up-regulation of the canonical Wnt-3A and Sonic hedgehog signaling underlies melanocortin-induced neurogenesis after cerebral ischemia
2013, European Journal of PharmacologyCitation Excerpt :Indeed, melanocortins – which act by stimulation of G protein-coupled, seven-transmembrane receptors (MC1–MC5) – are largely distributed in the CNS, where MC3 and MC4 are the predominant subtypes of melanocortin receptors expressed (Bertolini et al., 2009; Catania, 2008; Catania et al., 2004; Corander et al., 2009; Giuliani et al., 2012; Lasaga et al., 2008; Mountjoy, 2010; Wikberg and Mutulis, 2008). MC4 receptors have been repeatedly reported by ourselves to mediate the protective effect of melanocortins against ischemic stroke (Giuliani et al., 2006a, 2006b, 2007, 2009, 2011; Spaccapelo et al., 2011). Accordingly, here we report that pharmacological blockade of melanocortin MC4 receptors with the selective MC4 receptor blocking agent HS024 prevented the positive effects of NDP-α-MSH on the Wnt-3A/β-catenin and Shh signaling pathways.