1
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Bacon EK, Donnelly CG, Bellone RR, Haase B, Finno CJ, Velie BD. Preliminary investigation of potential links between pigmentation variants and opioid analgesic effectiveness in horses during cerebrospinal fluid centesis. BMC Vet Res 2024; 20:311. [PMID: 38997753 PMCID: PMC11245827 DOI: 10.1186/s12917-024-04139-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Accepted: 06/17/2024] [Indexed: 07/14/2024] Open
Abstract
BACKGROUND The pleiotropic effects of the melanocortin system show promise in overcoming limitations associated with large variations in opioid analgesic effectiveness observed in equine practice. Of particular interest is variation in the melanocortin-1-receptor (MC1R) gene, which dictates pigment type expression through its epistatic interaction with the agouti signalling protein (ASIP) gene. MC1R has previously been implicated in opioid efficacy in other species; however, this relationship is yet to be explored in horses. In this study, analgesic effectiveness was scored (1-3) based on noted response to dura penetration during the performance of cerebrospinal fluid centisis after sedation and tested for association with known genetic regions responsible for pigmentation variation in horses. RESULTS The chestnut phenotype was statistically significant (P < 0.05) in lowering analgesic effectiveness when compared to the bay base coat colour. The 11bp indel in ASIP known to cause the black base coat colour was not significant (P>0.05); however, six single nucleotide polymorphisms (SNPs) within the genomic region encoding the ASIP gene and one within MC1R were identified as being nominally significant (P<0.05) in association with opioid analgesic effectiveness. This included the location of the known e MC1R variant resulting in the chestnut coat colour. CONCLUSIONS The current study provides promising evidence for important links between pigmentation genes and opioid effectiveness in horses. The application of an easily identifiable phenotype indicating variable sensitivity presents a promising opportunity for accessible precision medicine in the use of analgesics and warrants further investigation.
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Affiliation(s)
- Elouise K Bacon
- Equine Genetics and Genomics Group, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia.
| | - Callum G Donnelly
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA
- Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithica, NY, 14850, USA
| | - Rebecca R Bellone
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA
| | - Bianca Haase
- School of Veterinary Science, University of Sydney, Sydney, NSW, Australia
| | - Carrie J Finno
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616, USA
| | - Brandon D Velie
- Equine Genetics and Genomics Group, School of Life and Environmental Sciences, University of Sydney, Sydney, NSW, Australia
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2
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Bacon EK, Donnelly CG, Bellone RR, Finno CJ, Velie BD. Melanocortin‐1 receptor influence in equine opioid sensitivity. EQUINE VET EDUC 2022. [DOI: 10.1111/eve.13661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Elouise K. Bacon
- Equine Genetics and Genomics Group School of Life and Environmental Sciences University of Sydney Sydney New South Wales Australia
| | - Callum G. Donnelly
- Department of Population Health and Reproduction School of Veterinary Medicine University of California Davis California USA
| | - Rebecca R. Bellone
- Department of Population Health and Reproduction School of Veterinary Medicine University of California Davis California USA
- Veterinary Genetics Laboratory School of Veterinary Medicine University of California Davis California USA
| | - Carrie J. Finno
- Department of Population Health and Reproduction School of Veterinary Medicine University of California Davis California USA
| | - Brandon D. Velie
- Equine Genetics and Genomics Group School of Life and Environmental Sciences University of Sydney Sydney New South Wales Australia
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3
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Melanocortin-4 receptor signaling in the central amygdala mediates chronic inflammatory pain effects on nociception. Neuropharmacology 2022; 210:109032. [PMID: 35304172 DOI: 10.1016/j.neuropharm.2022.109032] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/22/2022] [Accepted: 03/12/2022] [Indexed: 11/24/2022]
Abstract
Chronic inflammatory pain represents one of the largest subsets of chronic pain diagnoses, which affect nearly a quarter of individuals in the United States and cost nearly $600 billion dollars annually. Chronic pain leads to persistent sensory hypersensitivities, as well as emotional and cognitive disturbances. Evidence suggests that melanocortin 4 receptors (MC4Rs) mediate pain-signaling and pain-like behaviors via actions at various nodes in the pain-neural axis, but the field lacks a complete understanding of the potential role of MC4Rs in chronic inflammatory pain in males and females. The central amygdala (CeA) expresses high quantities of MC4R and receives pain-related information from the periphery, and in vivo CeA manipulations alter nociceptive behavior in pain-naïve and in animals with chronic pain. Here, we tested the hypothesis that MC4Rs in the CeA modulate thermal nociception and mechanical sensitivity, as well as pain avoidance, in male and female Wistar rats, using a model of chronic inflammatory pain (Complete Freud's Adjuvant; CFA). First, we report that CFA produces long-lasting hyperalgesia in adult male and female Wistar rats, and long-lasting pain avoidance in male Wistar rats. Second, we report that MC4R antagonism in the CeA reduces thermal nociception and mechanical sensitivity in male and female Wistar rats treated with CFA. Finally, we report that MC4R antagonism in the CeA reduces pain avoidance in male, and that this effect is not due to drug effects on locomotor activity. Our results indicate that a model of chronic inflammatory pain produces long-lasting increases in pain-like behaviors in adult male and female Wistar rats, and that antagonism of MC4Rs in the CeA reverses those effects.
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4
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Israeli H, Degtjarik O, Fierro F, Chunilal V, Gill AK, Roth NJ, Botta J, Prabahar V, Peleg Y, Chan LF, Ben-Zvi D, McCormick PJ, Niv MY, Shalev-Benami M. Structure reveals the activation mechanism of the MC4 receptor to initiate satiation signaling. Science 2021; 372:808-814. [PMID: 33858992 DOI: 10.1126/science.abf7958] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 04/08/2021] [Indexed: 12/18/2022]
Abstract
Obesity is a global epidemic that causes morbidity and impaired quality of life. The melanocortin receptor 4 (MC4R) is at the crux of appetite, energy homeostasis, and body-weight control in the central nervous system and is a prime target for anti-obesity drugs. Here, we present the cryo-electron microscopy (cryo-EM) structure of the human MC4R-Gs signaling complex bound to the agonist setmelanotide, a cyclic peptide recently approved for the treatment of obesity. The work reveals the mechanism of MC4R activation, highlighting a molecular switch that initiates satiation signaling. In addition, our findings indicate that calcium (Ca2+) is required for agonist, but not antagonist, efficacy. These results fill a gap in the understanding of MC4R activation and could guide the design of future weight-management drugs.
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Affiliation(s)
- Hadar Israeli
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Oksana Degtjarik
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Fabrizio Fierro
- The Faculty of Agriculture, Food and Environment, The Hebrew University, Rehovot, Israel
- The Fritz Haber Center for Molecular Dynamics, The Hebrew University, Jerusalem, Israel
| | - Vidicha Chunilal
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary, University of London, Charterhouse Square, London, UK
| | - Amandeep Kaur Gill
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary, University of London, Charterhouse Square, London, UK
| | - Nicolas J Roth
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary, University of London, Charterhouse Square, London, UK
| | - Joaquin Botta
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary, University of London, Charterhouse Square, London, UK
| | - Vadivel Prabahar
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Yoav Peleg
- Structural Proteomics Unit (SPU), Life Sciences Core Facilities (LSCF), Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Li F Chan
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary, University of London, Charterhouse Square, London, UK
| | - Danny Ben-Zvi
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel.
| | - Peter J McCormick
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary, University of London, Charterhouse Square, London, UK.
| | - Masha Y Niv
- The Faculty of Agriculture, Food and Environment, The Hebrew University, Rehovot, Israel.
- The Fritz Haber Center for Molecular Dynamics, The Hebrew University, Jerusalem, Israel
| | - Moran Shalev-Benami
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
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Piotrowska A, Starnowska-Sokół J, Makuch W, Mika J, Witkowska E, Tymecka D, Ignaczak A, Wilenska B, Misicka A, Przewłocka B. Novel bifunctional hybrid compounds designed to enhance the effects of opioids and antagonize the pronociceptive effects of nonopioid peptides as potent analgesics in a rat model of neuropathic pain. Pain 2021; 162:432-445. [PMID: 32826750 PMCID: PMC7808367 DOI: 10.1097/j.pain.0000000000002045] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 07/20/2020] [Accepted: 07/29/2020] [Indexed: 12/27/2022]
Abstract
ABSTRACT The purpose of our work was to determine the role of nonopioid peptides derived from opioid prohormones in sensory hypersensitivity characteristics of neuropathic pain and to propose a pharmacological approach to restore the balance of these endogenous opioid systems. Nonopioid peptides may have a pronociceptive effect and therefore contribute to less effective opioid analgesia in neuropathic pain. In our study, we used unilateral chronic constriction injury (CCI) of the sciatic nerve as a neuropathic pain model in rats. We demonstrated the pronociceptive effects of proopiomelanocortin- and proenkephalin-derived nonopioid peptides assessed by von Frey and cold plate tests, 7 to 14 days after injury. The concentration of proenkephalin-derived pronociceptive peptides was increased more robustly than that of Met-enkephalin in the ipsilateral lumbar spinal cord of CCI-exposed rats, as shown by mass spectrometry, and the pronociceptive effect of one of these peptides was blocked by an antagonist of the melanocortin 4 (MC4) receptor. The above results confirm our hypothesis regarding the possibility of creating an analgesic drug for neuropathic pain based on enhancing opioid activity and blocking the pronociceptive effect of nonopioid peptides. We designed and synthesized bifunctional hybrids composed of opioid (OP) receptor agonist and MC4 receptor antagonist (OP-linker-MC4). Moreover, we demonstrated that they have potent and long-lasting antinociceptive effects after a single administration and a delayed development of tolerance compared with morphine after repeated intrathecal administration to rats subjected to CCI. We conclude that the bifunctional hybrids OP-linker-MC4 we propose are important prototypes of drugs for use in neuropathic pain.
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Affiliation(s)
- Anna Piotrowska
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland
| | - Joanna Starnowska-Sokół
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland
| | - Wioletta Makuch
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland
| | - Joanna Mika
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland
| | - Ewa Witkowska
- Faculty of Chemistry, Biological, and Chemistry Research Centre, University of Warsaw, Warsaw, Poland
| | - Dagmara Tymecka
- Faculty of Chemistry, Biological, and Chemistry Research Centre, University of Warsaw, Warsaw, Poland
| | - Angelika Ignaczak
- Faculty of Chemistry, Biological, and Chemistry Research Centre, University of Warsaw, Warsaw, Poland
| | - Beata Wilenska
- Faculty of Chemistry, Biological, and Chemistry Research Centre, University of Warsaw, Warsaw, Poland
| | - Aleksandra Misicka
- Faculty of Chemistry, Biological, and Chemistry Research Centre, University of Warsaw, Warsaw, Poland
| | - Barbara Przewłocka
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland
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6
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Sharfman N, Gilpin NW. The Role of Melanocortin Plasticity in Pain-Related Outcomes After Alcohol Exposure. Front Psychiatry 2021; 12:764720. [PMID: 34803772 PMCID: PMC8599269 DOI: 10.3389/fpsyt.2021.764720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/05/2021] [Indexed: 11/13/2022] Open
Abstract
The global COVID-19 pandemic has shone a light on the rates and dangers of alcohol misuse in adults and adolescents in the US and globally. Alcohol exposure during adolescence causes persistent molecular, cellular, and behavioral changes that increase the risk of alcohol use disorder (AUD) into adulthood. It is established that alcohol abuse in adulthood increases the likelihood of pain hypersensitivity and the genesis of chronic pain, and humans report drinking alcohol to relieve pain symptoms. However, the longitudinal effects of alcohol exposure on pain and the underlying CNS signaling that mediates it are understudied. Specific brain regions mediate pain effects, alcohol effects, and pain-alcohol interactions, and neural signaling in those brain regions is modulated by neuropeptides. The CNS melanocortin system is sensitive to alcohol and modulates pain sensitivity, but this system is understudied in the context of pain-alcohol interactions. In this review, we focus on the role of melanocortin signaling in brain regions sensitive to alcohol and pain, in particular the amygdala. We also discuss interactions of melanocortins with other peptide systems, including the opioid system, as potential mediators of pain-alcohol interactions. Therapeutic strategies that target the melanocortin system may mitigate the negative consequences of alcohol misuse during adolescence and/or adulthood, including effects on pain-related outcomes.
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Affiliation(s)
- Nathan Sharfman
- Department of Physiology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Nicholas W Gilpin
- Department of Physiology, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, United States.,Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA, United States.,Alcohol and Drug Abuse Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA, United States.,Southeast Louisiana VA Healthcare System (SLVHCS), New Orleans, LA, United States
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7
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Starnowska-Sokół J, Piotrowska A, Bogacka J, Makuch W, Mika J, Witkowska E, Godlewska M, Osiejuk J, Gątarz S, Misicka A, Przewłocka B. Novel hybrid compounds, opioid agonist+melanocortin 4 receptor antagonist, as efficient analgesics in mouse chronic constriction injury model of neuropathic pain. Neuropharmacology 2020; 178:108232. [PMID: 32750445 DOI: 10.1016/j.neuropharm.2020.108232] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/24/2020] [Accepted: 07/06/2020] [Indexed: 12/30/2022]
Abstract
When the nerve tissue is injured, endogenous agonist of melanocortin type 4 (MC4) receptor, α-MSH, exerts tonic pronociceptive action in the central nervous system, contributing to sustaining the neuropathic pain state and counteracting the analgesic effects of exogenous opioids. With the intent of enhancing opioid analgesia in neuropathy by blocking the MC4 activation, so-called parent compounds (opioid agonist, MC4 antagonist) were joined together using various linkers to create novel bifunctional hybrid compounds. Analgesic action of four hybrids was tested after intrathecal (i.t.) administration in mouse models of acute and neuropathic pain (chronic constriction injury model, CCI). Under nerve injury conditions, one of the hybrids, UW3, induced analgesia in 1500 times lower i.t. dose than the opioid parent (ED50: 0.0002 nmol for the hybrid, 0.3 nmol for the opioid parent) and in an over 16000 times lower dose than the MC4 parent (ED50: 3.33 nmol) as measured by the von Frey test. Two selected hybrids were tested for analgesic properties in CCI mice after intravenous (i.v.) and intraperitoneal (i.p.) administration. Opioid receptor antagonists and MC4 receptor agonists diminished the analgesic action of these two hybrids studied, though the extent of this effect differed between the hybrids; this suggests that linker is of key importance here. Further results indicate a significant advantage of hybrid compounds over the physical mixture of individual pharmacophores in their analgesic effect. All this evidence justifies the idea of synthesizing a bifunctional opioid agonist-linker-MC4 antagonist compound, as such structure may bring important benefits in neuropathic pain treatment.
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Affiliation(s)
- Joanna Starnowska-Sokół
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland
| | - Anna Piotrowska
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland
| | - Joanna Bogacka
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland
| | - Wioletta Makuch
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland
| | - Joanna Mika
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland
| | - Ewa Witkowska
- University of Warsaw, Faculty of Chemistry, Biological and Chemistry Research Centre, Warsaw, Poland
| | - Magda Godlewska
- University of Warsaw, Faculty of Chemistry, Biological and Chemistry Research Centre, Warsaw, Poland
| | - Jowita Osiejuk
- University of Warsaw, Faculty of Chemistry, Biological and Chemistry Research Centre, Warsaw, Poland
| | - Sandra Gątarz
- University of Warsaw, Faculty of Chemistry, Biological and Chemistry Research Centre, Warsaw, Poland
| | - Aleksandra Misicka
- University of Warsaw, Faculty of Chemistry, Biological and Chemistry Research Centre, Warsaw, Poland
| | - Barbara Przewłocka
- Maj Institute of Pharmacology, Polish Academy of Sciences, Department of Pain Pharmacology, Krakow, Poland.
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8
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Zhang Y, Jiang D, Li H, Sun Y, Jiang X, Gong S, Qian Z, Tao J. Melanocortin type 4 receptor-mediated inhibition of A-type K + current enhances sensory neuronal excitability and mechanical pain sensitivity in rats. J Biol Chem 2019; 294:5496-5507. [PMID: 30745360 DOI: 10.1074/jbc.ra118.006894] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/07/2019] [Indexed: 12/28/2022] Open
Abstract
α-Melanocyte-stimulating hormone (α-MSH) has been shown to be involved in nociception, but the underlying molecular mechanisms remain largely unknown. In this study, we report that α-MSH suppresses the transient outward A-type K+ current (I A) in trigeminal ganglion (TG) neurons and thereby modulates neuronal excitability and peripheral pain sensitivity in rats. Exposing small-diameter TG neurons to α-MSH concentration-dependently decreased I A This α-MSH-induced I A decrease was dependent on the melanocortin type 4 receptor (MC4R) and associated with a hyperpolarizing shift in the voltage dependence of A-type K+ channel inactivation. Chemical inhibition of phosphatidylinositol 3-kinase (PI3K) with wortmannin or of class I PI3Ks with the selective inhibitor CH5132799 prevented the MC4R-mediated I A response. Blocking Gi/o-protein signaling with pertussis toxin or by dialysis of TG neurons with the Gβγ-blocking synthetic peptide QEHA abolished the α-MSH-mediated decrease in I A Further, α-MSH increased the expression levels of phospho-p38 mitogen-activated protein kinase, and pharmacological or genetic inhibition of p38α abrogated the α-MSH-induced I A response. Additionally, α-MSH significantly increased the action potential firing rate of TG neurons and increased the sensitivity of rats to mechanical stimuli applied to the buccal pad area, and both effects were abrogated by I A blockade. Taken together, our findings suggest that α-MSH suppresses I A by activating MC4R, which is coupled sequentially to the Gβγ complex of the Gi/o-protein and downstream class I PI3K-dependent p38α signaling, thereby increasing TG neuronal excitability and mechanical pain sensitivity in rats.
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Affiliation(s)
- Yuan Zhang
- From the Department of Geriatrics, the Second Affiliated Hospital of Soochow University, Suzhou 215004, China.,the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China
| | - Dongsheng Jiang
- the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China.,the Comprehensive Pneumology Center, Helmholtz Zentrum München, Munich 81377, Germany, and
| | - Hua Li
- the National Shanghai Center for New Drug Safety Evaluation and Research, Shanghai 201203, China
| | - Yufang Sun
- the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China
| | - Xinghong Jiang
- the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China
| | - Shan Gong
- the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China
| | - Zhiyuan Qian
- From the Department of Geriatrics, the Second Affiliated Hospital of Soochow University, Suzhou 215004, China,
| | - Jin Tao
- the Department of Physiology and Neurobiology and Centre for Ion Channelopathy, Medical College of Soochow University, Suzhou 215123, China, .,the Jiangsu Key Laboratory of Neuropsychiatric Diseases, Soochow University, Suzhou 215123, China
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9
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Abstract
Although the brain is well established as a master regulator of homeostasis in peripheral tissues, central regulation of bone mass represents a novel and rapidly expanding field of study. This review examines the current understanding of central regulation of the skeleton, exploring several of the key pathways connecting brain to bone and their implications both in mice and the clinical setting. Our understanding of central bone regulation has largely progressed through examination of skeletal responses downstream of nutrient regulatory pathways in the hypothalamus. Mutations and modulation of these pathways, in cases such as leptin deficiency, induce marked bone phenotypes, which have provided vital insights into central bone regulation. These studies have identified several central neuropeptide pathways that stimulate well-defined changes in bone cell activity in response to changes in energy homeostasis. In addition, this work has highlighted the endocrine nature of the skeleton, revealing a complex cross talk that directly regulates other organ systems. Our laboratory has studied bone-active neuropeptide pathways and defined osteoblast-based actions that recapitulate central pathways linking bone, fat, and glucose homeostasis. Studies of neural control of bone have produced paradigm-shifting changes in our understanding of the skeleton and its relationship with the wider array of organ systems.
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Affiliation(s)
- Alexander Corr
- 1 The Division of Bone Biology, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.,2 Faculty of Science, University of Bath, Bath, United Kingdom
| | - James Smith
- 1 The Division of Bone Biology, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.,2 Faculty of Science, University of Bath, Bath, United Kingdom
| | - Paul Baldock
- 1 The Division of Bone Biology, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.,3 Faculty of Medicine, St Vincent's Clinical School, University of New South Wales, Sydney, New South Wales, Australia.,4 School of Medicine Sydney, University of Notre Dame Australia, Sydney, New South Wales, Australia
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10
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Sasanuma H, Nakata M, Parmila K, Nakae J, Yada T. PDK1-FoxO1 pathway in AgRP neurons of arcuate nucleus promotes bone formation via GHRH-GH-IGF1 axis. Mol Metab 2017; 6:428-439. [PMID: 28462077 PMCID: PMC5404105 DOI: 10.1016/j.molmet.2017.02.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 02/11/2017] [Indexed: 01/13/2023] Open
Abstract
Objective In the hypothalamic arcuate nucleus (ARC), orexigenic agouti-related peptide (AgRP) neurons regulate feeding behavior and energy homeostasis, functions connected to bone metabolism. The 3-phosphoinositide-dependent protein kinase-1 (PDK1) serves as a major signaling molecule particularly for leptin and insulin in AgRP neurons. We asked whether PDK1 in AGRP neurons also contributes to bone metabolism. Methods We generated AgRP neuron-specific PDK1 knockout (Agrp Pdk1−/−) mice and those with additional AgRP neuron-specific expression of transactivation-defective FoxO1 (Agrp Pdk1−/−Δ256Foxo1). Bone metabolism in KO and WT mice was analyzed by quantitative computed tomography (QCT), bone histomorphometry, measurement of plasma biomarkers, and qPCR analysis of peptides. Results In Agrp Pdk1−/− female mice aged 6 weeks, compared with Agrp Cre mice, both stature and femur length were shorter while body weight was unchanged. Cortical bone mineral density (BMD) and cancellous BMD in the femur decreased, and bone formation was delayed. Furthermore, plasma GH and IGF-1 levels were reduced in parallel with decreased mRNA expressions for GH in pituitary and GHRH in ARC. Osteoblast activity was suppressed and osteoclast activity was enhanced. These changes in stature, BMD and GH level were rescued in Agrp Pdk1−/−Δ256Foxo1 mice, suggesting that the bone abnormalities and impaired GH release were mediated by enhanced Foxo1 due to deletion of PDK1. Conclusions This study reveals a novel role of PDK1-Foxo1 pathway of AgRP neurons in controlling bone metabolism primarily via GHRH-GH-IGF-1 axis. Agrp neuron-selective Pdk1 knockout mice exhibit short stature, shortened limbs and decreased bone density in both cortical and cancellous bones. In Agrp Pdk1 knockout mice, GHRH-GH-IGF1 axis was markedly down-regulated. Retarded bone growth and reduced GH in Agrp Pdk1 knockout mice were rescued by additional expression of dominant negative FoxO1 in AgRP neurons. Pdk1-FoxO1 signaling in AgRP neurons is linked to regulation of GHRH-GH-IGF1 axis and bone metabolism.
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Affiliation(s)
- Hideyuki Sasanuma
- Department of Physiology, Division of Integrative Physiology, Jichi Medical University, 3311-1 Yakushiji, Tochigi, Shimotsuke, 329-0498, Japan; Department of Orthopaedic Surgery, Faculty of Medicine, Jichi Medical University, 3311-1 Yakushiji, Tochigi, Shimotsuke, 329-0498, Japan
| | - Masanori Nakata
- Department of Physiology, Division of Integrative Physiology, Jichi Medical University, 3311-1 Yakushiji, Tochigi, Shimotsuke, 329-0498, Japan.
| | - Kumari Parmila
- Department of Physiology, Division of Integrative Physiology, Jichi Medical University, 3311-1 Yakushiji, Tochigi, Shimotsuke, 329-0498, Japan
| | - Jun Nakae
- Frontier Medicine on Metabolic Syndrome, Division of Endocrinology, Metabolism and Nephrology, Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan
| | - Toshihiko Yada
- Department of Physiology, Division of Integrative Physiology, Jichi Medical University, 3311-1 Yakushiji, Tochigi, Shimotsuke, 329-0498, Japan.
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11
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Neuropeptides and Microglial Activation in Inflammation, Pain, and Neurodegenerative Diseases. Mediators Inflamm 2017; 2017:5048616. [PMID: 28154473 PMCID: PMC5244030 DOI: 10.1155/2017/5048616] [Citation(s) in RCA: 143] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 11/26/2016] [Accepted: 12/05/2016] [Indexed: 12/15/2022] Open
Abstract
Microglial cells are responsible for immune surveillance within the CNS. They respond to noxious stimuli by releasing inflammatory mediators and mounting an effective inflammatory response. This is followed by release of anti-inflammatory mediators and resolution of the inflammatory response. Alterations to this delicate process may lead to tissue damage, neuroinflammation, and neurodegeneration. Chronic pain, such as inflammatory or neuropathic pain, is accompanied by neuroimmune activation, and the role of glial cells in the initiation and maintenance of chronic pain has been the subject of increasing research over the last two decades. Neuropeptides are small amino acidic molecules with the ability to regulate neuronal activity and thereby affect various functions such as thermoregulation, reproductive behavior, food and water intake, and circadian rhythms. Neuropeptides can also affect inflammatory responses and pain sensitivity by modulating the activity of glial cells. The last decade has witnessed growing interest in the study of microglial activation and its modulation by neuropeptides in the hope of developing new therapeutics for treating neurodegenerative diseases and chronic pain. This review summarizes the current literature on the way in which several neuropeptides modulate microglial activity and response to tissue damage and how this modulation may affect pain sensitivity.
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Wee NKY, Kulkarni RN, Horsnell H, Baldock PA. The brain in bone and fuel metabolism. Bone 2016; 82:56-63. [PMID: 26545334 DOI: 10.1016/j.bone.2015.10.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 10/01/2015] [Accepted: 10/31/2015] [Indexed: 12/24/2022]
Abstract
Obesity and osteoporosis have become major public health challenges worldwide. The brain is well established as a pivotal regulator of energy homeostasis, appetite and fuel metabolism. However, there is now clear evidence for regulation between the brain and bone. Similarly, evidence also indicates that the involvement of the brain in bone and adipose regulation is both related and interdependent. The hypothalamus, with its semi-permeable blood brain barrier, is one of the most powerful regulatory regions within the body, integrating and relaying signals not only from peripheral tissues but also from within the brain itself. Two main neuronal populations within the arcuate nucleus of the hypothalamus regulate energy homeostasis: The orexigenic, appetite-stimulating neurons that co-express neuropeptide Y and agouti-related peptide and the anorexigenic, appetite-suppressing neurons that co-express proopiomelanocortin and cocaine- and amphetamine related transcript. From within the arcuate, these four neuropeptides encompass some of the most powerful control of energy homeostasis in the entire body. Moreover, they also regulate skeletal homeostasis, identifying a co-ordination network linking the processes of bone and energy homeostasis. Excitingly, the number of central neuropeptides and neural factors known to regulate bone and energy homeostasis continues to grow, with cannabinoid receptors and semaphorins also involved in bone homeostasis. These neuronal pathways represent a growing area of research that is identifying novel regulatory axes between the brain and the bone, and links with other homeostatic networks; thereby revealing a far more complex, and interdependent bone biology than previously envisioned. This review examines the current understanding of the central regulation of bone and energy metabolism.
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Affiliation(s)
- Natalie K Y Wee
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia
| | - Rishikesh N Kulkarni
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia
| | - Harry Horsnell
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia; Department of Biology and Biochemistry, Bath University, Bath, UK
| | - Paul A Baldock
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia; Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia; School of Medicine, The University of Notre Dame Australia, Sydney, NSW, Australia.
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13
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Houweling P, Kulkarni RN, Baldock PA. Neuronal control of bone and muscle. Bone 2015; 80:95-100. [PMID: 26453499 DOI: 10.1016/j.bone.2015.05.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 04/27/2015] [Accepted: 05/04/2015] [Indexed: 12/30/2022]
Abstract
The functional interplay between bone and muscle that enables locomotion is a fundamental aspect of daily life. However, other interactions between bone and muscle continue to attract attention as our understanding of the breath and importance of this inter-relationship continues to expand. Of particular interest is the regulatory connection between bone and muscle, which adds a new insight to the coordination of the bone/muscle unit. We have appreciated the importance of neuronal signaling to the control of bone turnover and muscle contraction, but recent data indicate that neuronal inputs control a far wider range of bone and muscle physiology than previously appreciated. This review outlines the role of the sympathetic nervous system and neuronal/neuropeptide inputs upon the regulation of bone and muscle tissue, and the potential for co-regulatory actions, particularly involving the sympathetic nervous system. This article is part of a Special Issue entitled "Muscle Bone Interactions".
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Affiliation(s)
- Peter Houweling
- Murdoch Childrens Research Institute, The Royal Children's Hospital, Melbourne, VIC, Australia; Department of Paediatrics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, VIC, Australia
| | - Rishikesh N Kulkarni
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia
| | - Paul A Baldock
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, NSW, Australia; Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia; School of Medicine, The University of Notre Dame Australia, Sydney, NSW, Australia.
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Caruso V, Lagerström MC, Olszewski PK, Fredriksson R, Schiöth HB. Synaptic changes induced by melanocortin signalling. Nat Rev Neurosci 2014; 15:98-110. [PMID: 24588018 DOI: 10.1038/nrn3657] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The melanocortin system has a well-established role in the regulation of energy homeostasis, but there is growing evidence of its involvement in memory, nociception, mood disorders and addiction. In this Review, we focus on the role of the melanocortin 4 receptor and provide an integrative view of the molecular mechanisms that lead to melanocortin-induced changes in synaptic plasticity within these diverse physiological systems. We also highlight the importance of melanocortin peptides and receptors in chronic pain syndromes, memory impairments, depression and drug abuse, and the possibility of targeting them for therapeutic purposes.
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15
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Chu H, Sun J, Xu H, Niu Z, Xu M. Effect of periaqueductal gray melanocortin 4 receptor in pain facilitation and glial activation in rat model of chronic constriction injury. Neurol Res 2012; 34:871-88. [PMID: 22889616 DOI: 10.1179/1743132812y.0000000085] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES Substantial evidence shows that spinal melanocortin 4 receptor (MC4R) may participate in regulation of central sensitization and chronic pain condition induced by peripheral nerve injury. Periaqueductal gray (PAG) is an important component of descending pain facilitatory system and takes part in spinal nociceptive information. This research will choose PAG to discuss the effect of MC4R in pain facilitation induced by chronic constriction injury (CCI) and further discuss its effect in glial activity and inflammatory factor levels in nerve injury. METHODS Behavior tests (von Frey test and hot-plate test), semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), and immunohistochemistry were used in this research. RESULTS PAG injection of HS014 (a selective inhibitor of MC4R), not only significantly reduced the established mechanical allodynia and thermal hyperalgesia, but also delayed the development of pain facilitation. Semi-quantitative RT-PCR analysis revealed that MC4R and proopiomelanocortin (POMC) expression in PAG was significantly increased after CCI, but agouti-related protein (AgRP) expression decreased. Immunohistochemistry analysis showed that protein levels of astrocytic marker (GFAP), microglial marker (OX-42), tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, and IL-6 were significantly increased, but there was little change of the protein levels of IL-10 following CCI. Furthermore, blockade of MC4R decreased immunoreactivity of glia cells and protein levels of pro-inflammatory cytokines, and increased protein levels of anti-inflammatory cytokine IL-10 after CCI. DISCUSSION This research suggests that activation of MC4R in PAG after peripheral nerve injury participates in pain facilitation by regulating the glial activation and inflammatory cytokines secretion.
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Affiliation(s)
- Haichen Chu
- Department of Anesthesiology, Affiliated Hospital of Medical College, Qingdao University, China.
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16
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Abstract
The melanocortin-4 receptor (MC4R) was cloned in 1993 by degenerate PCR; however, its function was unknown. Subsequent studies suggest that the MC4R might be involved in regulating energy homeostasis. This hypothesis was confirmed in 1997 by a series of seminal studies in mice. In 1998, human genetic studies demonstrated that mutations in the MC4R gene can cause monogenic obesity. We now know that mutations in the MC4R are the most common monogenic form of obesity, with more than 150 distinct mutations reported thus far. This review will summarize the studies on the MC4R, from its cloning and tissue distribution to its physiological roles in regulating energy homeostasis, cachexia, cardiovascular function, glucose and lipid homeostasis, reproduction and sexual function, drug abuse, pain perception, brain inflammation, and anxiety. I will then review the studies on the pharmacology of the receptor, including ligand binding and receptor activation, signaling pathways, as well as its regulation. Finally, the pathophysiology of the MC4R in obesity pathogenesis will be reviewed. Functional studies of the mutant MC4Rs and the therapeutic implications, including small molecules in correcting binding and signaling defect, and their potential as pharmacological chaperones in rescuing intracellularly retained mutants, will be highlighted.
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Affiliation(s)
- Ya-Xiong Tao
- Department of Anatomy, Physiology, and Pharmacology, Auburn University, Alabama 36849-5519, USA.
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17
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Starowicz K, Mousa SA, Obara I, Chocyk A, Przewłocki R, Wędzony K, Machelska H, Przewłocka B. Peripheral antinociceptive effects of MC4 receptor antagonists in a rat model of neuropathic pain – a biochemical and behavioral study. Pharmacol Rep 2009; 61:1086-95. [DOI: 10.1016/s1734-1140(09)70171-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2009] [Revised: 10/19/2009] [Indexed: 10/25/2022]
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18
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Zhang YQ, Guo N, Peng G, Wang X, Han M, Raincrow J, Chiu CH, Coolen LM, Wenthold RJ, Zhao ZQ, Jing N, Yu L. Role of SIP30 in the development and maintenance of peripheral nerve injury-induced neuropathic pain. Pain 2009; 146:130-40. [PMID: 19748740 DOI: 10.1016/j.pain.2009.07.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2009] [Revised: 07/11/2009] [Accepted: 07/13/2009] [Indexed: 01/24/2023]
Abstract
Using the chronic constriction injury (CCI) model of neuropathic pain, we profiled gene expression in the rat spinal cord, and identified SIP30 as a gene whose expression was elevated after CCI. SIP30 was previously shown to interact with SNAP25, but whose function was otherwise unknown. We now show that in the spinal cord, SIP30 was present in the dorsal horn laminae where the peripheral nociceptive inputs first synapse, co-localizing with nociception-related neuropeptides CGRP and substance P. With the onset of neuropathic pain after CCI surgery, SIP30 mRNA and protein levels increased in the ipsilateral side of the spinal cord, suggesting a potential association between SIP30 and neuropathic pain. When CCI-upregulated SIP30 was inhibited by intrathecal antisense oligonucleotide administration, neuropathic pain was attenuated. This neuropathic pain-reducing effect was observed both during neuropathic pain onset following CCI, and after neuropathic pain was fully established, implicating SIP30 involvement in the development and maintenance phases of neuropathic pain. Using a secretion assay in PC12 cells, anti-SIP30 siRNA decreased the total pool of synaptic vesicles available for exocytosis, pointing to a potential function for SIP30. These results suggest a role of SIP30 in the development and maintenance of peripheral nerve injury-induced neuropathic pain.
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Affiliation(s)
- Yu-Qiu Zhang
- Department of Cell Biology, Neurobiology and Anatomy, University of Cincinnati College of Medicine, Cincinnati, OH, USA
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Trigo JM, Zimmer A, Maldonado R. Nicotine anxiogenic and rewarding effects are decreased in mice lacking beta-endorphin. Neuropharmacology 2009; 56:1147-53. [PMID: 19376143 DOI: 10.1016/j.neuropharm.2009.03.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 03/25/2009] [Accepted: 03/26/2009] [Indexed: 11/16/2022]
Abstract
The endogenous opioid system plays an important role in the behavioral effects of nicotine. Thus, micro-opioid receptor and the endogenous opioids derived from proenkephalin are involved in the central effects of nicotine. However, the role played by the different endogenous opioid peptides in the acute and chronic effects of nicotine remains to be fully established. Mice lacking beta-endorphin were acutely injected with nicotine at different doses to evaluate locomotor, anxiogenic and antinociceptive responses. The rewarding properties of nicotine were evaluated by using the conditioned place-preference paradigm. Mice chronically treated with nicotine were acutely injected with mecamylamine to study the behavioral expression of nicotine withdrawal. Mice lacking beta-endorphin exhibited a spontaneous hypoalgesia and hyperlocomotion and a reduction on the anxiogenic and rewarding effects induced by nicotine. Nicotine induced similar antinociception and hypolocomotion in both genotypes and no differences were found in the development of physical dependence. The dissociation between nicotine rewarding properties and physical dependence suggests a differential implication of beta-endorphin in these addictive related responses.
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Affiliation(s)
- José M Trigo
- Laboratori de Neurofarmacologia, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona, Spain.
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20
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Ilnytska O, Sözen MA, Dauterive R, Argyropoulos G. Control elements in the neighboring ATPase gene influence spatiotemporal expression of the human agouti-related protein. J Mol Biol 2009; 388:239-51. [PMID: 19285986 DOI: 10.1016/j.jmb.2009.03.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Revised: 03/04/2009] [Accepted: 03/09/2009] [Indexed: 11/17/2022]
Abstract
The agouti-related protein (AgRP) is an orexigenic peptide that plays a significant role in the regulation of energy balance. It is expressed in the hypothalamus, the adrenal glands, and the testis, but sequences determining its spatial and temporal expression have not been identified. Using an elaborate in vitro screening approach, we show here that two adjacent enhancers inside the first intron of the neighboring (1.4 kb downstream) ATPase gene (ATP6V0D1) modulate the human AgRP promoter with profound spatiotemporal variation despite their diminutive sizes (221 and 231 nt). In transgenic mice, the proximal enhancer displayed specificity for the testis, tail, and ears, and the distal one for the testis, front feet, bone, heart, muscle, brain, spinal cord, and tongue, while dietary fat and overnight fasting had differential effects on enhancer activities. AgRP in the testis was localized to pachytene spermatocytes and in the tongue to epithelial cells. Comparative sequence analysis showed that the AgRP-ATP6V0D1 intergenic region is two times longer in humans than in mice and that the two enhancers are conserved in the rhesus monkey genome but not in the mouse genome. These data show that spatiotemporal expression of the human AgRP gene is influenced by diversified primate-specific intronic sequences in its neighboring ATP6V0D1 gene.
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Affiliation(s)
- Olha Ilnytska
- Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA 70809, USA
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21
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Wong IP, Zengin A, Herzog H, Baldock PA. Central regulation of bone mass. Semin Cell Dev Biol 2008; 19:452-8. [DOI: 10.1016/j.semcdb.2008.08.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2008] [Revised: 08/01/2008] [Accepted: 08/04/2008] [Indexed: 11/27/2022]
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22
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Abstract
The Agouti-Related Protein (AgRP) is a powerful orexigenic peptide that increases food intake when ubiquitously overexpressed or when administered centrally. AgRP-deficiency, on the other hand, leads to increased metabolic rate and a longer lifespan when mice consume a high fat diet. In humans, AgRP polymorphisms have been consistently associated with resistance to fatness in Blacks and Whites and resistance to the development of type-2 diabetes in African Blacks. Systemically administered AgRP accumulates in the liver, the adrenal gland and fat tissue while recent findings suggest that AgRP may also have inverse agonist effects, both centrally and peripherally. AgRP could thus modulate energy balance via different actions. Its absence or reduced functionality may offer a benefit both in terms of bringing about negative energy balance in obesigenic environments, as well as leading to an increased lifespan.
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Affiliation(s)
- O. Ilnytska
- Pennington Biomedical Research Center, LSU System, Baton Rouge, Louisiana, 70809 USA
| | - G. Argyropoulos
- Pennington Biomedical Research Center, LSU System, Baton Rouge, Louisiana, 70809 USA
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23
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Sharma HS, Skottner A, Lundstedt T, Flärdh M, Wiklund L. Neuroprotective effects of melanocortins in experimental spinal cord injury. An experimental study in the rat using topical application of compounds with varying affinity to melanocortin receptors. J Neural Transm (Vienna) 2006; 113:463-76. [PMID: 16550325 DOI: 10.1007/s00702-005-0404-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2005] [Accepted: 09/26/2005] [Indexed: 01/10/2023]
Abstract
The possibility that local administration of low molecular weight non-peptide compounds with varying affinities at melanocortin receptors in the spinal cord will influence pathophysiological outcome of spinal cord injury (SCI) was examined in a rat model. Five new Melacure compounds ME10092, ME10354, ME10393, ME10431 and ME10501 were used in this investigation. Each compound was dissolved in saline and tested at 3 different doses, i.e. 1 microg, 5 microg and 10 microg total dose in 10 microl applied topically 5 min after SCI. The animals were allowed to survive 5 h and trauma induced edema formation, breakdown of the blood-spinal cord barrier (BSCB) and cell injuries were examined and compared with untreated injured rats. A focal SCI inflicted by an incision into the right dorsal horn of the T10-11 segments resulted in marked edema formation, breakdown of the BSCB to Evans blue albumin and caused profound nerve cell injury in the T9 and the T12 segments. Topical application of ME10501 (a compound with high affinity at melanocortin, MC-4 receptors) in high doses (10 microg) resulted in most marked neuroprotection in the perifocal spinal cord (T9 and T12) segments. On the other hand, only a mild or no effect on spinal cord pathology was observed in the traumatized animals that received ME10092, ME10354, ME10393 and ME10431 at 3 different doses. These observations suggest that non-peptide compounds with varying affinity to melanocortin receptors are able to influence the pathophysiology of SCI. Furthermore, compounds acting at melanocortin, MCR4 receptors are capable to induce neuroprotection in spinal cord following trauma.
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Affiliation(s)
- H S Sharma
- Laboratory of Cerebrovascular Research, Department of Surgical Sciences, Division of Anaesthesiology and Intensive Care Medicine, University Hospital, Uppsala University, Uppsala, Sweden.
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Chaki S, Okuyama S. Involvement of melanocortin-4 receptor in anxiety and depression. Peptides 2005; 26:1952-64. [PMID: 15979204 DOI: 10.1016/j.peptides.2004.11.029] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2004] [Accepted: 11/14/2004] [Indexed: 10/25/2022]
Abstract
The melanocortins, which are derived from proopiomelanocortin, have a variety of physiological functions mediated membrane surface receptors. To date, five subtypes have been cloned. With the cloning of melanocortin receptors, studies with genetic models, and development of selective compounds, the physiological roles of the five melanocortin receptors have begun to be understood. The melanocortin-4 receptor (MC4R), which is predominantly expressed in the central nervous system, has in particular become the focus of much attention in recent years because of the critical roles it plays in a wide range of functions, including feeding, sexual behavior, and stress. Recent development of selective antagonists for the MC4R has provided pharmacological evidence that blockade of MC4R could be a useful way of alleviating numerous conditions such as anxiety/depression, pain, and addiction to drugs of abuse.
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Affiliation(s)
- Shigeyuki Chaki
- Medicinal Research Laboratories, Taisho Pharmaceutical Co. Ltd., 1-403 Yoshino-cho, Kita-ku, Saitama 331-9530, Japan
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25
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Stütz AM, Morrison CD, Argyropoulos G. The agouti-related protein and its role in energy homeostasis. Peptides 2005; 26:1771-81. [PMID: 15961186 DOI: 10.1016/j.peptides.2004.12.024] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Accepted: 12/01/2004] [Indexed: 12/30/2022]
Abstract
The melanocortin system plays an important role in the regulation of energy homeostasis. The Agouti-related protein (AGRP) is a natural antagonist of the action of alpha-melanocyte stimulating hormone (alpha-MSH) at the melanocortin receptors (MCR). AGRP is upregulated by fasting while intracerebroventricular injections of synthetic AGRP lead to increased appetite and food intake. Transgenic mice overexpressing AGRP are also hyperphagic and eventually become obese. AGRP is, therefore, a significant regulator of energy balance and a candidate gene for human fatness. Indeed, humans with common single nucleotide polymorphisms (SNPs) in the promoter or the coding region are leaner and resistant to late-onset obesity than wild-type individuals. AGRP is also expressed in the periphery. Recent studies show that AGRP in the adrenal gland is upregulated by fasting as much as it is in the hypothalamus. These data open up the possibility for a wider role by AGRP not only in food intake but also in the regulation of energy balance through its actions on peripheral tissues. This review summarizes recent advances in the biochemical and physiological properties of AGRP in an effort to enhance our understanding of the role this powerful neuropeptide plays in mammalian energy homeostasis.
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Affiliation(s)
- Adrian M Stütz
- Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA
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26
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Tran JA, Pontillo J, Arellano M, Fleck BA, Tucci FC, Marinkovic D, Chen CW, Saunders J, Foster AC, Chen C. Structure–activity relationship of a series of cyclohexylpiperidines bearing an amide side chain as antagonists of the human melanocortin-4 receptor. Bioorg Med Chem Lett 2005; 15:3434-8. [PMID: 15950470 DOI: 10.1016/j.bmcl.2005.05.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2005] [Revised: 04/29/2005] [Accepted: 05/03/2005] [Indexed: 11/16/2022]
Abstract
A series of cyclohexylpiperazines was synthesized as potent and selective antagonists of the human MC4 receptor. Compound 14t displayed binding affinity (Ki) of 4.2 and 1100 nM at MC4R and MC3R, respectively.
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Affiliation(s)
- Joseph A Tran
- Department of Medicinal Chemistry, Neurocrine Biosciences, Inc., 12790 El Camino Real, San Diego, CA 92130, USA
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Pontillo J, Tran JA, Markison S, Joppa M, Fleck BA, Marinkovic D, Arellano M, Tucci FC, Lanier M, Nelson J, Saunders J, Hoare SRJ, Foster AC, Chen C. A potent and selective nonpeptide antagonist of the melanocortin-4 receptor induces food intake in satiated mice. Bioorg Med Chem Lett 2005; 15:2541-6. [PMID: 15863313 DOI: 10.1016/j.bmcl.2005.03.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 03/10/2005] [Accepted: 03/15/2005] [Indexed: 10/25/2022]
Abstract
Optimization on a series of piperazinebenzylamines resulted in analogues with low nanomolar binding at the human MC4 receptor but weak affinity (Ki > 500 nM) at the MC3 receptor. Compound 14c was identified to be a potent MC4R antagonist (Ki = 3.2 nM) with a selectivity of 240-fold over MC3R. It proved to be an insurmountable antagonist in a cAMP assay. Compound 14c potently stimulated food intake in satiated mice when given by intracerebroventricular administration.
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Affiliation(s)
- Joseph Pontillo
- Department of Medicinal Chemistry, Neurocrine Biosciences, Inc., 12790 El Camino Real, San Diego, CA 92130, USA
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28
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Bertorelli R, Fredduzzi S, Tarozzo G, Campanella M, Grundy R, Beltramo M, Reggiani A. Endogenous and exogenous melanocortin antagonists induce anti-allodynic effects in a model of rat neuropathic pain. Behav Brain Res 2005; 157:55-62. [PMID: 15617771 DOI: 10.1016/j.bbr.2004.06.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2004] [Revised: 06/08/2004] [Accepted: 06/09/2004] [Indexed: 11/23/2022]
Abstract
A number of studies suggest melanocortin (MC) system involvement in nociceptive modulation. Although the mechanism through which this occurs is still unknown, experimental evidence would suggest a primary role of MC4 receptors. To further investigate the implication of this MC receptor subtype in chronic pain, we have studied the effects of several MC antagonists on spinal nerve ligation-induced nociceptive behavior in rats. The intrathecal injection of synthetic antagonists with different selectivity to MC4 receptor and of an endogenous antagonist (Agouti related protein; AgRP) reduced mechanical allodynia in neuropathic rats, as measured by von Frey hair test. Treatments produced an anti-allodynic effect at the dose of 1.5 nmol (25-30% maximum possible effect, MPE, P<0.05). To further investigate the possible physiological role of AgRP in pain modulation we studied its expression in both sham and neuropathic rat spinal cord and dorsal root ganglia (DRG) by quantitative real time PCR and immunohistochemistry. AgRP was present in both spinal cord and DRG, and its expression, was unchanged in neuropathic animals. In conclusion MC4 receptor antagonists with different selectivity profile, induce anti-allodynic effects in one of the most relevant neuropathic pain model. In addition the expression of AgRP in spinal cord and DRG suggests an endogenous tonic inhibitory control on MC system activity. In pathological conditions this steady control could be insufficient to cope with an over activated MC system leading to increase in nociception. These data suggest that targeting MC4 with synthetic antagonists could restore the balance and hence reduce nociception.
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MESH Headings
- Agouti-Related Protein
- Animals
- Disease Models, Animal
- Ganglia, Spinal/metabolism
- Immunohistochemistry
- Injections, Spinal
- Intercellular Signaling Peptides and Proteins
- Male
- Pain/drug therapy
- Pain/metabolism
- Proteins/administration & dosage
- Proteins/genetics
- Proteins/metabolism
- RNA, Messenger/analysis
- Rats
- Rats, Sprague-Dawley
- Receptor, Melanocortin, Type 3/antagonists & inhibitors
- Receptor, Melanocortin, Type 3/metabolism
- Receptor, Melanocortin, Type 4/antagonists & inhibitors
- Receptor, Melanocortin, Type 4/metabolism
- Sciatic Neuropathy/drug therapy
- Sciatic Neuropathy/metabolism
- Spinal Cord/metabolism
- Spinal Nerves/drug effects
- Spinal Nerves/metabolism
- Tissue Distribution
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Affiliation(s)
- Rosalia Bertorelli
- Schering Plough Research Institute, San Raffaele Science Park, Via Olgettina, 58, 20132 Milan, Italy.
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