Volume 2 • Issue 2 • 1000113 Neurochem Neuropharm Open Access journal ISSN: 2469-9780 Research Article Open Access Neurochemistry & Neuropharmacology N e u r o c h e m i s t r y & N e u r o p h a r m a c o l o g y ISSN: 2469-9780 Mohan et al., Neuropharm Open Access 2016, 2:2 DOI: 10.4172/2469-9780.1000113 Keywords: Heme; Protein kinase A; Inlammation; Neurons; Morphine; Opioid receptor Introduction he toxicity of free heme has been documented in several disease types. For example, in hemolytic anemias such as sickle cell disease and thalassemia, release of heme from hemoglobin following lysis of red blood cells is known to cause cell death [1,2]. In a critical care situation such as hemorrhagic injury, neuronal cell death is caused by the lysis of red blood cells, which release hemoglobin and its breakdown product hemin [3-5]. Physiological levels of free heme in the blood are maintained at low levels (0.1 -1 μM) by the high binding ainity of proteins such as serum albumin, hemopexin and haptoglobin [6- 8]. When internalized, free heme is catabolized by heme oxygenases (HO1 and HO2 isoforms) and therefore the amount of cellular damage free heme produces is limited by the stress-responsive HO1 isoform [9]. In addition to HO1 and HO2 isoform regulated cellular damage, the oxidative state of iron (from Fe 2+ to Fe 3+ via the Fenton reaction) within heme can produce harmful superoxide free radicals in the brain that can lead to oxidative stress, initiation of lipid peroxidation and neuronal death. Pathological conditions can increase the level of heme and iron. For example in acute conditions such as severe hemolytic crisis in sickle cell disease, heme levels can increase up to 20 μM or to greater than 200 μM (supraphysiological levels) in thalassemia [10]. herefore, further studies on the cross talk between neuroinlammatory mediators and iron-containing hemoproteins such as hemin are warranted. Morphine is a non-selective opioid receptor agonist and analgesic agent used in clinical practice to manage pain. Morphine and morphinans (class of compounds containing the basic morphine structure) agents have been shown to be neuroprotective in various models of inlammation and neurodegeneration. For example, morphine pretreatment of purkinje cells and hippocampal slices provided ischemic tolerance [11,12]. he same group also recently discovered that morphine-mediated neuroprotection was not only NMDA receptor mediated but also miR-134 dependent in primary cortical neuronal cultures [13]. Besides it critical role in anti- nociception, activation of the Mu-opioid receptor promotes cell proliferation and also afects neuronal diferentiation both in vitro and in vivo [14-16]. Studies have shown that morphine protects neurons against microglia-mediated neuroinlammation and oxidative stress [17]. More recently, activation of the Mu- receptor attenuated β-amyloid peptide neurotoxicity through an mTOR-dependent mechanism [18]. For a more comprehensive review of morphinans mediated neuroprotection, Zhang et al. published a review in 2004 that discusses the utility of opioids in neurodegerative disease. he role of opioid Morphine-Mediated Cytoprotection against Hemin in SK-N-SH and A172 Cells Shekher Mohan*, Tanner Robinson, Noah Allen, Lance Armstrong and Sarah Stevens Department of Pharmaceutical Science and Research, School of Pharmacy, Marshall University, Huntington, WV, USA Abstract Study background: Heme and its catabolized form, hemin, are cytotoxic due to their ability to contribute to the production of reactive oxygen species, increase intracellular calcium levels and stimulate glutamate mediated-excitotoxicity. Previous work has shown that activation of the opioid receptors (i.e., mu, kappa and delta) is neuroprotective against ischemia-induced neuronal death and neurotoxicity induced by Aβ oligomers in vitro. However, the role of these opioid receptor in hemin toxicity remains unknown. Activation of the Mu-receptor results in decreased 3, 5’-cyclic adenosine monophosphate (cAMP) and adenylyl cyclase activity, which then results in reduced cAMP-dependent Ca 2+ inlux. Therefore, we hypothesized that the activation of the opioid receptors by morphine may decrease hemin toxicity. Methods: The human neuroblastoma SK-N-SH and human astroglia A172 cells were treated with hemin (3.125, 6.25, 12.5, 25, 50 and 75 μM) for 18 h. In separate experiments, both cells types were pre- and co-treated with opioid receptor agonist morphine (10 μM) and hemin (75 μM) or naltrexone (10 μM) alone and pre- and co- treatment with hemin (75 μM) for 18 h. Cell viability was assessed using two assays, LDH and the number of live cells measured using the Calcein-AM assay. Results: In both SK-N-SH and A172 cells, hemin-dose dependently induced signiicant cell death compared to the vehicle control. When pre-treated and co-treated with morphine, hemin toxicity in both cell types was signiicantly attenuated. The protection mediated by morphine from hemin was blocked by opioid antagonist, naltrexone. Conclusion: Together, the results suggest that activation of the opioid receptors my morphine is protective against hemin toxicity in vitro and these indings suggest that cytoprotection may occur through the cAMP-AC pathway. Therefore, activation of for example the Mu-receptor could be used to minimize neuronal and glial damage following exposure to supraphysiological levels of hemin. *Corresponding author: Shekher Mohan, Department of Pharmaceutical Science and Research, School of Pharmacy, Marshall University, One John Marshall Drive, Huntington, WV, 25755, USA, Tel: +13046967371; E-mail: mohans@marshall.edu Received August 15, 2016; Accepted August 31, 2016; Published September 02, 2016 Citation: Mohan S, Robinson T, Allen N, Armstrong L, Stevens S (2016) Morphine- Mediated Cytoprotection against Hemin in SK-N-SH and A172 Cells. Neurochem Neuropharm Open Access 2: 113. doi: 10.4172/2469-9780.1000113 Copyright: © 2016 Mohan S, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.