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Gallagher DM, O'Harte FPM, Irwin N. An update on galanin and spexin and their potential for the treatment of type 2 diabetes and related metabolic disorders. Peptides 2024; 171:171096. [PMID: 37714335 DOI: 10.1016/j.peptides.2023.171096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/04/2023] [Accepted: 09/11/2023] [Indexed: 09/17/2023]
Abstract
Spexin (SPX) and galanin (GAL) are two neuropeptides widely expressed in the central nervous system as well as within peripheral tissues in humans and other species. SPX and GAL mediate their biological actions through binding and activation of galanin receptors (GALR), namely GALR1, GALR2 and GLAR3. GAL appears to trigger all three galanin receptors, whereas SPX interacts more specifically with GALR2 and GLAR3. Whilst the biological effects of GAL have been well-described over the years, in-depth knowledge of physiological action profile of SPX is still in its preliminary stages. However, it is recognised that both peptides play a significant role in modulating overall energy homeostasis, suggesting possible therapeutically exploitable benefits in diseases such as obesity and type 2 diabetes mellitus. Accordingly, although both peptides activate GALR's, it appears GAL may be more useful for the treatment of eating disorders such as anorexia and bulimia, whereas SPX may find therapeutic application for obesity and obesity-driven forms of diabetes. This short narrative review aims to provide an up-to-date account of SPX and GAL biology together with putative approaches on exploiting these peptides for the treatment of metabolic disorders.
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Affiliation(s)
- Daniel M Gallagher
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, BT52 1SA, UK
| | - Finbarr P M O'Harte
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, BT52 1SA, UK
| | - Nigel Irwin
- Diabetes Research Centre, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, BT52 1SA, UK.
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Abstract
SignificanceGalanin exerts various physiological functions through galanin receptors, including antinociceptive activity, depression, and sleep. Here, we reveal a distinct binding mode of galanin peptide in galanin receptors from that of the published structures of peptide-bound GPCRs. Moreover, our work shows that the neuromodulator zinc ion negatively modulates galanin signaling in the central nervous system and further advances our understanding of mechanisms of G protein selectivity of GPCRs. These structures will provide a framework for rational design of ligands targeting GALRs for potential therapeutic applications.
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Dong Y, Li CY, Zhang XM, Liu YN, Yang S, Li MN, Xu SL. The activation of galanin receptor 2 plays an antinociceptive effect in nucleus accumbens of rats with neuropathic pain. J Physiol Sci 2021; 71:6. [PMID: 33546583 PMCID: PMC10717428 DOI: 10.1186/s12576-021-00790-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 01/07/2021] [Indexed: 11/10/2022]
Abstract
Our previous research has shown that galanin plays an antinociceptive effect via binding to galanin receptors (GalRs) in nucleus accumbens (NAc). This study focused on the involvement of GalR2 in galanin-induced antinociceptive effect in NAc of neuropathic pain rats. The chronic constriction injury of sciatic nerve (CCI) was used to mimic neuropathic pain model. The hind paw withdrawal latency (HWL) to thermal stimulation and hind paw withdrawal threshold (HWT) to mechanical stimulation were measured as the indicators of pain threshold. The results showed that 14 and 28 days after CCI, the expression of GalR2 was up-regulated in bilateral NAc of rats, and intra-NAc injection of GalR2 antagonist M871 reversed galanin-induced increases in HWL and HWT of CCI rats. Furthermore, intra-NAc injection of GalR2 agonist M1145 induced increases in HWL and HWT at day 14 and day 28 after CCI, which could also be reversed by M871. Finally, we found that M1145-induced antinociceptive effect in NAc of CCI rats was stronger than that in intact rats. These results imply that the GalR2 is activated in the NAc from day 14 to day 28 after CCI and GalR2 is involved in the galanin-induced antinociceptive effect in NAc of CCI rats.
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Affiliation(s)
- Yan Dong
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Chong-Yang Li
- Department of Oncology, Affiliated Hospital, Yunnan University, Kunming, Yunnan, China
| | - Xiao-Min Zhang
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Ya-Nan Liu
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Shuang Yang
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Meng-Nan Li
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, 650500, Yunnan, China
| | - Shi-Lian Xu
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, 650500, Yunnan, China.
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Li M, Zhang X, Li C, Liu Y, Yang S, Xu S. Galanin Receptor 2 Is Involved in Galanin-Induced Analgesic Effect by Activating PKC and CaMKII in the Nucleus Accumbens of Inflammatory Pain Rats. Front Neurosci 2021; 14:593331. [PMID: 33551722 PMCID: PMC7859109 DOI: 10.3389/fnins.2020.593331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 12/28/2020] [Indexed: 11/13/2022] Open
Abstract
It has been reported that galanin has an analgesic effect via activating galanin receptors (GALRs). This study focused on the involvement of GALR2 in the galanin-induced analgesic effect and its signaling mechanism in the nucleus accumbens (NAc) of inflammatory rats. Animal models were established through injecting carrageenan into the plantar of rats’ left hind paw. The results showed that GALR2 antagonist M871 weakened partially the galanin-induced increases in hind paw withdrawal latency (HWL) to thermal stimulation and hind paw withdrawal threshold (HWT) to mechanical stimulation in NAc of inflammatory rats. Moreover, the GALR2 agonist M1145 prolonged the HWL and HWT, while M871 blocked the M1145-induced increases in HWL and HWT. Western blotting showed that the phosphorylation of calcium/calmodulin-dependent protein kinase II (p-CaMKII) and protein kinase C (p-PKC) in NAc were upregulated after carrageenan injection, while p-PKC and p-CaMKII were downregulated after intra-NAc administration of M871. Furthermore, the CaMKII inhibitor KN93 and PKC inhibitor GO6983 attenuated M1145-induced increases in HWL and HWT in NAc of rats with inflammatory pain. These results prove that GALR2 is involved in the galanin-induced analgesic effect by activating CaMKII and PKC in NAc of inflammatory pain rats, implying that GALR2 agonists probably are potent therapeutic options for inflammatory pain.
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Affiliation(s)
- Mengnan Li
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, China
| | - Xiaomin Zhang
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, China
| | - Chongyang Li
- Department of Oncology, Affiliated Hospital, Yunnan University, Kunming, China
| | - Yanan Liu
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, China
| | - Shuang Yang
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, China
| | - Shilian Xu
- Department of Physiology, School of Basic Medicine, Kunming Medical University, Kunming, China
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Leidmaa E, Gazea M, Patchev AV, Pissioti A, Christian Gassen N, Kimura M, Liposits Z, Kallo I, Almeida OFX. Blunted leptin sensitivity during hedonic overeating can be reinstated by activating galanin 2 receptors (Gal2R) in the lateral hypothalamus. Acta Physiol (Oxf) 2020; 228:e13345. [PMID: 31310704 DOI: 10.1111/apha.13345] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 07/08/2019] [Accepted: 07/11/2019] [Indexed: 12/13/2022]
Abstract
AIM Since foods with high hedonic value are often consumed in excess of energetic needs, this study was designed to identify the mechanisms that may counter anorexigenic signalling in the presence of hedonic foods in lean animals. METHODS Mice, in different states of satiety (fed/fasted, or fed/fasted and treated with ghrelin or leptin, respectively), were allowed to choose between high-fat/high-sucrose and standard foods. Intake of each food type and the activity of hypothalamic neuropetidergic neurons that regulate appetite were monitored. In some cases, food choice was monitored in leptin-injected fasted mice that received microinjections of galanin receptor agonists into the lateral hypothalamus. RESULTS Appetite-stimulating orexin neurons in the lateral hypothalamus are rapidly activated when lean, satiated mice consume a highly palatable food (PF); such activation (upregulated c-Fos expression) occurred even after administration of the anorexigenic hormone leptin and despite intact leptin signalling in the hypothalamus. The ability of leptin to restrain PF eating is restored when a galanin receptor 2 (Gal2R) agonist is injected into the lateral hypothalamus. CONCLUSION Hedonically-loaded foods interrupt the inhibitory actions of leptin on orexin neurons and interfere with the homeostatic control of feeding. Overeating of palatable foods can be curtailed in lean animals by activating Gal2R in the lateral hypothalamus.
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Affiliation(s)
- Este Leidmaa
- Max Planck Institute of Psychiatry Munich Germany
- Graduate School of Systems Neuroscience Munich University Planegg‐Martinsried Germany
- Institute of Molecular Psychiatry Bonn Germany
| | - Mary Gazea
- Max Planck Institute of Psychiatry Munich Germany
| | | | | | | | | | - Zsolt Liposits
- Institute of Experimental Medicine Hungarian Academy of Sciences Budapest Hungary
| | - Imre Kallo
- Institute of Experimental Medicine Hungarian Academy of Sciences Budapest Hungary
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Palkeeva ME, Sidorova MV, Molokoedov AS, Ovchinnikov MV, Az’muko AA, Serebryakova LI, Veselova OM, Studneva IM, Pisarenko OI. Fragments of the Galanin Peptide and Their Synthetic Analogues with the Cardioprotective Effect. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2019. [DOI: 10.1134/s1068162019040071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Brunner SM, Koller A, Stockinger J, Sternberg F, Leis S, Ernst F, Strasser P, Brodowicz B, Ebner S, Holub BS, Rauch I, Graf K, Lang R, Kofler B. Validation of antibody-based tools for galanin research. Peptides 2019; 120:170009. [PMID: 30196126 DOI: 10.1016/j.peptides.2018.08.010] [Citation(s) in RCA: 8] [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: 06/13/2018] [Revised: 08/02/2018] [Accepted: 08/22/2018] [Indexed: 12/17/2022]
Abstract
Antibodies are an integral biomedical tool, not only for research but also as therapeutic agents. However, progress can only be made with sensitive and specific antibodies. The regulatory (neuro)peptide galanin and its three endogenous receptors (GAL1-3-R) are widely distributed in the central and peripheral nervous systems, and in peripheral non-neuronal tissues. The galanin system has multiple biological functions, including feeding behavior, pain processing, nerve regeneration and inflammation, to name only a few. Galanin could serve as biomarker in these processes, and therefore its receptors are potential drug targets for various diseases. For that reason, it is of paramount interest to precisely measure galanin peptide levels in tissues and to determine the cellular and subcellular localization of galanin receptors. A plethora of antibodies and antibody-based tools, including radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) kits, are commercially available to detect galanin and its receptors. However, many of them lack rigorous validation which casts doubt on their specificity. A goal of the present study was to raise awareness of the importance of validation of antibodies and antibody-based tools, with a specific focus on the galanin system. To that end, we tested and report here about commercially available antibodies against galanin and galanin receptors that appear specific to us. Furthermore, we investigated the validity of commercially available galanin ELISA kits. As the tested ELISAs failed to meet the validation requirements, we developed and validated a specific sandwich ELISA which can be used to detect full-length galanin in human plasma.
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Affiliation(s)
- Susanne M Brunner
- Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
| | - Andreas Koller
- Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
| | - Julia Stockinger
- Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
| | - Felix Sternberg
- Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
| | - Stefan Leis
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, University Hospital of the Paracelsus Medical University, Ignaz-Harrer-Straße 79, 5020, Salzburg, Austria.
| | - Florian Ernst
- Department of Neurology, Christian Doppler Medical Centre and Centre for Cognitive Neuroscience, University Hospital of the Paracelsus Medical University, Ignaz-Harrer-Straße 79, 5020, Salzburg, Austria.
| | - Peter Strasser
- University Institute for Medical & Chemical Laboratory Diagnostic, University Hospital of the Paracelsus Medical University, Ignaz-Harrer-Straße 79, 5020, Salzburg, Austria.
| | - Bernhard Brodowicz
- Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
| | - Sabine Ebner
- Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
| | - Barbara S Holub
- Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
| | - Isabella Rauch
- Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
| | - Kerstin Graf
- Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
| | - Roland Lang
- Department of Dermatology, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
| | - Barbara Kofler
- Research Program for Receptor Biochemistry and Tumor Metabolism, Department of Pediatrics, University Hospital of the Paracelsus Medical University, Muellner Hauptstraße 48, 5020, Salzburg, Austria.
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Serebryakova LI, Studneva IM, Ovchinnikov MV, Veselova OM, Molokoedov AS, Arzamastsev EV, Afanasyeva EY, Terekhova OA, Sidorova MV, Pisarenko OI. [Cardiometabolic efficacy and toxicological evaluation of a pharmacological galanin receptor agonist]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2019; 65:231-238. [PMID: 31258147 DOI: 10.18097/pbmc20196503231] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The goal of this study was to examine effects of a novel galanin receptor agonist GalR1-3 [bAla14, His15]-galanine 2-15 (G), obtained by automatic solid-phase synthesis, on the metabolic state of the area at risk and the size of acute myocardial infarction (MI) in rats in vivo and evaluate its toxicity in BALB /c mice. In anesthetized rats, regional ischemia was simulated by coronary artery occlusion and then coronary blood flow was restored. The peptide G was administered intravenously (i.v.) with a bolus after a period of regional ischemia in the dose range of 0.25-3.0 mg/kg. The sizes of MI and the activities of creatine kinase-MB (СK-MB) and lactate dehydrogenase (LDH) in blood plasma were estimated. The effect of administration of the optimal dose of G (1.0 mg/kg) on myocardial content of adenine nucleotides (AN), phosphocreatine (PCr), creatine (Cr) and lactate was studied. I.v. administration of G to rats at a dose of 1.0 mg/kg slightly affected hemodynamic parameters, but reduced MI size by 40% and decreased plasma LDH and CK-MB activity by the end of reperfusion compared to control. These effects were accompanied by a significant improvement in energy state of area at risk (AAR) - an increase in myocardial content of ATP, åAN, PCr and åCr, and combined with a decrease in myocardial lactate level compared with the control. Toxicity of peptide G was studied with a single intraperitoneal injection of 0.5-3.0% solution of the peptide substance to mice. The absence of signs of intoxication and death of animals after G injection in the maximum possible dose did not allow determining the value of the average lethal dose. The results indicate therapeutic potential of the peptide G for preventing myocardial ischemia and reperfusion injury and feasibility for further study of its pharmacological properties and mechanisms of action.
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Affiliation(s)
| | - I M Studneva
- National Medical Research Center for Cardiology, Moscow, Russia
| | - M V Ovchinnikov
- National Medical Research Center for Cardiology, Moscow, Russia
| | - O M Veselova
- National Medical Research Center for Cardiology, Moscow, Russia
| | - A S Molokoedov
- National Medical Research Center for Cardiology, Moscow, Russia
| | - E V Arzamastsev
- National Medical Research Center for Cardiology, Moscow, Russia
| | - E Yu Afanasyeva
- National Medical Research Center for Cardiology, Moscow, Russia
| | - O A Terekhova
- National Medical Research Center for Cardiology, Moscow, Russia
| | - M V Sidorova
- National Medical Research Center for Cardiology, Moscow, Russia
| | - O I Pisarenko
- National Medical Research Center for Cardiology, Moscow, Russia
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Galanin/GalR1-3 system: A promising therapeutic target for myocardial ischemia/reperfusion injury. Biomed Pharmacother 2018; 109:1556-1562. [PMID: 30551408 DOI: 10.1016/j.biopha.2018.09.182] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 09/11/2018] [Accepted: 09/28/2018] [Indexed: 01/06/2023] Open
Abstract
N-terminal fragments of galanin (2-11) and (2-15) are critical for binding to GalR1-3 receptors, members of the G-protein-coupled receptor superfamily, and are involved in myocardial protection against ischemia/reperfusion (I/R) injury. This study was designed to synthesize novel GalR1-3 agonists with improved properties and evaluate their efficiency as cardioprotective agents. Peptide agonists were synthesized by the automatic solid phase method using Fmoc technology and purified by preparative HPLC. Their chemical structure was identified by 1H-NMR spectroscopy and MALDI-TOF mass spectrometry. Novel ligands of galanin receptors have greater solubility in water than natural galanin fragments. Cardiac function indices, myocardial infarct size and plasma activity of creatine kinase-MB (CK-MB) and lactate dehydrogenase (LDH) were measured to assess the peptide bioactivity. Infusion of optimal concentrations of the peptides (210-240 μM) after global ischemia enhanced functional recovery of isolated rat heart during reperfusion. Intravenous administration of the peptides in a dose range of 1-2 mg/kg at the onset of reperfusion significantly reduced infarct size and plasma levels of CK-MB and LDH in rats in vivo. The chimeric ligand [βAla14, His15]-galanin (2-15) exhibited the most beneficial effect on both models of I/R injury. The results suggest that pharmacological agonists of GalR1-3 receptors can be a rational basis for drug developments in the field of cardiovascular diseases.
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Fang P, He B, Yu M, Shi M, Zhu Y, Zhang Z, Bo P. Central galanin receptor 2 mediates galanin action to promote systemic glucose metabolism of type 2 diabetic rats. Biochem Pharmacol 2018; 156:241-247. [PMID: 30170096 DOI: 10.1016/j.bcp.2018.08.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/22/2018] [Indexed: 12/22/2022]
Abstract
Although recent results of our and other studies have showed that galanin (GAL) is an antidiabetic and anti-inflammatory neuropeptide, the molecular mechanism how central GAL regulates energy homeostasis and insulin sensitivity is still not fully understood. The aim of this study was to investigate whether central type 2 of GAL receptors (GALR2) are involved in the regulation of systemic glucose metabolism and its underlying mechanisms. In the present study, type 2 diabetic rats were intracerebroventricularly (i.c.v.) given 100 nM/kg/d GALR2 agonist M1145 or GALR2 antagonist M871 in 5 μl artificial cerebrospinal fluid once a day for consecutive 21 days. Then insulin resistance indexes, inflammatory factor and many genes associated with the function of glucose metabolism were examined in peripheral tissues. The present findings showed that the intracerebroventricular injection of M1145 or M871 respectively increased or decreased glucose infusion rates in hyperinsulinemic euglycemic clamp tests, but attenuated or enhanced the plasma inflammatory factors and glucose concentration in type 2 diabetic rats. Moreover, administration of M1145 markedly increased PGC-1α and GLUT4 expression in skeletal muscles and adipocytes of type 2 diabetic rats. In conclusion, activation of central GALR2 promotes glucose metabolism and ameliorates insulin resistance mainly through the PGC-1α/GLUT4 pathways. The central GALR2 is crucial to whole-body insulin sensitivity and energy homeostasis.
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Affiliation(s)
- Penghua Fang
- Department of Physiology, Hanlin College, Nanjing University of Chinese Medicine, Taizhou 225300, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Medical College, Yangzhou University, Yangzhou 225001, China
| | - Biao He
- College of Physical Education, Anhui Normal University, Wuhu 241003, China
| | - Mei Yu
- Department of Physiology, Hanlin College, Nanjing University of Chinese Medicine, Taizhou 225300, China
| | - Mingyi Shi
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Medical College, Yangzhou University, Yangzhou 225001, China
| | - Yan Zhu
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou 225001, China
| | - Zhenwen Zhang
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou 225001, China.
| | - Ping Bo
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou 225001, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Medical College, Yangzhou University, Yangzhou 225001, China.
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11
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Fang P, Zhang L, Yu M, Sheng Z, Shi M, Zhu Y, Zhang Z, Bo P. Activiated galanin receptor 2 attenuates insulin resistance in skeletal muscle of obese mice. Peptides 2018; 99:92-98. [PMID: 29183756 DOI: 10.1016/j.peptides.2017.11.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 11/24/2017] [Accepted: 11/24/2017] [Indexed: 01/28/2023]
Abstract
The results of our and other's studies showed that activation of galanin receptor 1 could mitigate insulin resistance via promoting glucose transporter 4 (GLUT4) expression and translocation in the skeletal muscle of rats. But no literature are available regarding the effect of galanin receptor 2 (GALR2) on insulin resistance in skeletal muscle of type 2 diabetes. Herein, in this study we intended to survey the effect of GALR2 and its signal mechanisms in the mice with high fat diet-induced obese. The mice were intraperitoneally injected with vehicle, GALR2 agonist M1145 and antagonist M871 respectively once a day for continuous 21 days. The skeletal muscles were processed for determination of glucose uptake, and GLUT4 mRNA and protein expression levels. The PGC-1α, AKT, p38MAPK, AS160, pAKT, pP38MAPK and pAS160 expression levels were quantitatively assessed too. We found that pharmacological activation of GALR2 enhanced energy expenditure, and increased GLUT4 expression and translocation in skeletal muscle of mice during high-fat diet regimens. Activation of GALR2 alleviated insulin resistance through P38MAPK/PGC-1α/GLUT4 and AKT/AS160/GLUT4 pathway in the skeletal muscle of mice. Overall, these results identify that GALR2 is a regulator of insulin resistance and activation of GALR2 represents a promising strategy against obesity-induced insulin resistance.
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Affiliation(s)
- Penghua Fang
- Department of Physiology, Nanjing University of Chinese Medicine Hanlin College, Taizhou, Jiangsu, 225300, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Medical College, Yangzhou University, Yangzhou, 225001, China
| | - Lei Zhang
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Medical College, Yangzhou University, Yangzhou, 225001, China
| | - Mei Yu
- Department of Physiology, Nanjing University of Chinese Medicine Hanlin College, Taizhou, Jiangsu, 225300, China
| | - Zhongqi Sheng
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou, Jiangsu, 225001, China
| | - Mingyi Shi
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Medical College, Yangzhou University, Yangzhou, 225001, China
| | - Yan Zhu
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou, Jiangsu, 225001, China
| | - Zhenwen Zhang
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou, Jiangsu, 225001, China.
| | - Ping Bo
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou, Jiangsu, 225001, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Medical College, Yangzhou University, Yangzhou, 225001, China.
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12
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Khan D, Khan M, Runesson J, Zaben M, Gray WP. GalR3 mediates galanin proliferative effects on postnatal hippocampal precursors. Neuropeptides 2017; 63:14-17. [PMID: 28431685 DOI: 10.1016/j.npep.2017.04.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 02/23/2017] [Accepted: 04/05/2017] [Indexed: 11/16/2022]
Abstract
Galanin, a neuropeptide co-released from noradrenergic and serotonergic projection neurons to the dentate gyrus, has recently emerged as an important mediator for signaling neuronal activity to the subgranular neurogenic stem cell niche supporting adult hippocampal neurogenesis. Galanin and its receptors appear to play key roles in depression-like behavior, and effects on hippocampal neurogenesis are relevant to pharmacological strategies for treating depression, which in part appear to rely on restoring altered neurogenesis. We previously demonstrated that the GalR2/3 receptor agonist Gal 2-11 is proliferative and proneurogenic for postnatal hippocampal progenitor cells; however, the specific receptor mediation remained to be identified. With the recent availability of M1145 (a specific GalR2 agonist), and SNAP 37889 (GalR3 specific antagonist), we extend our previous studies and show that while M1145 has no proliferative effect, the co-treatment of postnatal rat hippocampal progenitors with Gal 2-11 and SNAP 37889 completely abolished the Gal 2-11 proliferative effects. Taken together, these results clearly demonstrate that GalR3 and not GalR2 is the specific receptor subtype that mediates the proliferative effects of galanin on hippocampal progenitor cells. These results implicate GALR3 in the mediation of galanin neurogenic effects and, potentially, its neurogenic anti-depressant effects.
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Affiliation(s)
- D Khan
- Institute of Psychological Medicine and Clinical Neurosciences, Neurosciences and Mental Health Research Institute NMHRI, Room 3.33, Hadyn Ellis Building, Cardiff CF24 4HQ, United Kingdom
| | - M Khan
- Institute of Psychological Medicine and Clinical Neurosciences, Neurosciences and Mental Health Research Institute NMHRI, Room 3.33, Hadyn Ellis Building, Cardiff CF24 4HQ, United Kingdom
| | - Johan Runesson
- Institute of Psychological Medicine and Clinical Neurosciences, Neurosciences and Mental Health Research Institute NMHRI, Room 3.33, Hadyn Ellis Building, Cardiff CF24 4HQ, United Kingdom
| | - M Zaben
- Institute of Psychological Medicine and Clinical Neurosciences, Neurosciences and Mental Health Research Institute NMHRI, Room 3.33, Hadyn Ellis Building, Cardiff CF24 4HQ, United Kingdom
| | - W P Gray
- Institute of Psychological Medicine and Clinical Neurosciences, Neurosciences and Mental Health Research Institute NMHRI, Room 3.33, Hadyn Ellis Building, Cardiff CF24 4HQ, United Kingdom.
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13
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Ihnatko R, Theodorsson E. Short N-terminal galanin fragments are occurring naturally in vivo. Neuropeptides 2017; 63:1-13. [PMID: 28434790 DOI: 10.1016/j.npep.2017.03.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/08/2017] [Accepted: 03/31/2017] [Indexed: 10/19/2022]
Abstract
UNLABELLED The galanin family currently consists of four peptides, namely galanin, galanin-message associated peptide, galanin-like peptide and alarin. Unlike galanin that signals through three different G protein-coupled receptors; GAL1, GAL2, and GAL3, binding at its N-terminal end, the cognate receptors for other members of the galanin family are currently unknown. Research using short N-terminal galanin fragments generated either by enzymatic cleavage or solid-phase synthesis has revealed differences in their receptor binding properties exerting numerous biological effects distinct from galanin(1-29) itself. Our studies on tissue extracts derived from rat small intestine and bovine gut using chromatographic techniques and sensitive galanin(1-16)-specific radioimmunoassay revealed the presence of immunoreactive compounds reacting with antiserum against galanin(1-16) distributed in distinct elution volumes. These results suggested a possible presence of short N-terminal galanin fragments also in vivo. Moreover, employing immunoaffinity chromatography and reverse-phase high performance liquid chromatography (HPLC) followed by mass spectrometry allowed specific enrichment of these immunoreactive compounds from rat tissues and identification of their molecular structure. Indeed, our study revealed presence of several distinct short N-terminal galanin sequences in rat tissue. To prove their receptor binding, four of the identified sequences were synthetized, namely, galanin(1-13), galanin(1-16), galanin(1-20), galanin(6-20), and tested on coronal rat brain sections competing with 125I-labeled galanin(1-29). Our autoradiographs confirmed that galanin(1-13), galanin(1-16), and galanin(1-20) comprehensively displaced 125I-galanin(1-29) but galanin(6-20) did not. Here we show, for the first time, that short N-terminal galanin fragments occur naturally in rat tissues and that similar or identical galanin sequences can be present also in tissues of other species. BIOLOGICAL SIGNIFICANCE This study is first to provide an evidence of the presence of short N-terminal galanin fragments in vivo in a biological system and provides further foundations for the previous studies using synthetized short N-terminal galanin fragments.
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Affiliation(s)
- Robert Ihnatko
- Department of Clinical Chemistry, Department of Clinical and Experimental Medicine, Linköping University, 58285 Linköping, Sweden.
| | - Elvar Theodorsson
- Department of Clinical Chemistry, Department of Clinical and Experimental Medicine, Linköping University, 58285 Linköping, Sweden
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14
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Webling K, Runesson J, Lang A, Saar I, Kofler B, Langel Ü. Ala 5-galanin (2-11) is a GAL 2R specific galanin analogue. Neuropeptides 2016; 60:75-82. [PMID: 27592409 DOI: 10.1016/j.npep.2016.08.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 08/11/2016] [Accepted: 08/22/2016] [Indexed: 12/18/2022]
Abstract
It is over 30years since the regulatory peptide galanin was discovered by Professor Mutt and co-workers. Galanin exerts its effects by binding to three galanin G-protein coupled receptors, namely GAL1R, GAL2R and GAL3R. Each galanin receptor has a different distribution in the central nervous system and the peripheral nervous system as well as distinctive signaling pathways, which implicates that the receptors are involved in different biological- and pathological effects. The delineation of the galaninergic system is however difficult due to a lack of stable, specific galanin receptor ligands. Herein, a new short GAL2R specific ligand, Ala5-galanin (2-11), is presented. The galanin (2-11) modified analogue Ala5-galanin (2-11) was tested in 125I-galanin competitive binding studies for the three galanin receptors and the G-protein coupled receptor signaling properties was tested by the ability to influence second-messenger molecules like inositol phosphate and cyclic adenosine monophosphate. In addition, two different label-free real-time assays, namely EnSpire® based on an optical biosensor and xCELLigence® based on an electric biosensor, were used for evaluating the signaling properties using cell lines with different levels of receptor expression. Ala5-galanin (2-11) was subsequently found to be a full agonist for GAL2R with more than 375-fold preference for GAL2R compared to both GAL1R and GAL3R. The single amino acid substitution of serine to alanine at position 5 in the short ligand galanin (2-11) resulted in a ligand subsequently unable to bind neither GAL3R nor GAL1R, even at concentrations as high as 0.1mM.
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Affiliation(s)
- Kristin Webling
- Department of Neurochemistry, Stockholm University, Svante Arrheniusv. 16B, SE-10691 Stockholm, Sweden.
| | - Johan Runesson
- Department of Neurochemistry, Stockholm University, Svante Arrheniusv. 16B, SE-10691 Stockholm, Sweden
| | - Andreas Lang
- Research Program for Receptorbiochemistry and Tumormetabolism, Laura Bassi Centre of Expertise THERAPEP, Department of Pediatrics, University Hospital Salzburg, Paracelsus Medical University, Müllner Hauptstr. 48, A-5020 Salzburg, Austria
| | - Indrek Saar
- Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia
| | - Barbara Kofler
- Research Program for Receptorbiochemistry and Tumormetabolism, Laura Bassi Centre of Expertise THERAPEP, Department of Pediatrics, University Hospital Salzburg, Paracelsus Medical University, Müllner Hauptstr. 48, A-5020 Salzburg, Austria
| | - Ülo Langel
- Department of Neurochemistry, Stockholm University, Svante Arrheniusv. 16B, SE-10691 Stockholm, Sweden; Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia
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15
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Constantin S, Wray S. Galanin Activates G Protein Gated Inwardly Rectifying Potassium Channels and Suppresses Kisspeptin-10 Activation of GnRH Neurons. Endocrinology 2016; 157:3197-212. [PMID: 27359210 PMCID: PMC4967115 DOI: 10.1210/en.2016-1064] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 06/21/2016] [Indexed: 12/21/2022]
Abstract
GnRH neurons are regulated by hypothalamic kisspeptin neurons. Recently, galanin was identified in a subpopulation of kisspeptin neurons. Although the literature thoroughly describes kisspeptin activation of GnRH neurons, little is known about the effects of galanin on GnRH neurons. This study investigated whether galanin could alter kisspeptin signaling to GnRH neurons. GnRH cells maintained in explants, known to display spontaneous calcium oscillations, and a long-lasting calcium response to kisspeptin-10 (kp-10), were used. First, transcripts for galanin receptors (GalRs) were examined. Only GalR1 was found in GnRH neurons. A series of experiments was then performed to determine the action of galanin on kp-10 activated GnRH neurons. Applied after kp-10 activation, galanin 1-16 (Gal1-16) rapidly suppressed kp-10 activation. Applied with kp-10, Gal1-16 prevented kp-10 activation until its removal. To determine the mechanism by which galanin inhibited kp-10 activation of GnRH neurons, Gal1-16 and galanin were applied to spontaneously active GnRH neurons. Both inhibited GnRH neuronal activity, independent of GnRH neuronal inputs. This inhibition was mimicked by a GalR1 agonist but not by GalR2 or GalR2/3 agonists. Although Gal1-16 inhibition relied on Gi/o signaling, it was independent of cAMP levels but sensitive to blockers of G protein-coupled inwardly rectifying potassium channels. A newly developed bioassay for GnRH detection showed Gal1-16 decreased the kp-10-evoked GnRH secretion below detection threshold. Together, this study shows that galanin is a potent regulator of GnRH neurons, possibly acting as a physiological break to kisspeptin excitation.
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Affiliation(s)
- Stephanie Constantin
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke/National Institutes of Health, Bethesda, Maryland 20892-3703
| | - Susan Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke/National Institutes of Health, Bethesda, Maryland 20892-3703
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16
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Webling K, Groves-Chapman JL, Runesson J, Saar I, Lang A, Sillard R, Jakovenko E, Kofler B, Holmes PV, Langel Ü. Pharmacological stimulation of GAL1R but not GAL2R attenuates kainic acid-induced neuronal cell death in the rat hippocampus. Neuropeptides 2016; 58:83-92. [PMID: 26764217 DOI: 10.1016/j.npep.2015.12.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Revised: 11/23/2015] [Accepted: 12/07/2015] [Indexed: 02/08/2023]
Abstract
The neuropeptide galanin is widely distributed in the central and peripheral nervous systems and part of a bigger family of bioactive peptides. Galanin exerts its biological activity through three G-protein coupled receptor subtypes, GAL1-3R. Throughout the last 20years, data has accumulated that galanin can have a neuroprotective effect presumably mediated through the activation of GAL1R and GAL2R. In order to test the pharmaceutical potential of galanin receptor subtype selective ligands to inhibit excitotoxic cell death, the GAL1R selective ligand M617 and the GAL2R selective ligand M1145 were compared to the novel GAL1/2R ligand M1154, in their ability to reduce the excitotoxic effects of intracerebroventricular injected kainate acid in rats. The peptide ligands were evaluated in vitro for their binding preference in a competitive (125)I-galanin receptor subtype binding assay, and G-protein signaling was evaluated using both classical signaling and a label-free real-time technique. Even though there was no significant difference in the time course or severity of the kainic acid induced epileptic behavior in vivo, administration of either M617 or M1154 before kainic acid administration significantly attenuated the neuronal cell death in the hippocampus. Our results indicate the potential therapeutic value of agonists selective for GAL1R in the prevention of neuronal cell death.
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MESH Headings
- Animals
- Bradykinin/analogs & derivatives
- Bradykinin/pharmacology
- Cell Death/drug effects
- Cell Line, Tumor
- Cyclic AMP/metabolism
- Galanin/analogs & derivatives
- Galanin/pharmacology
- Hippocampus/drug effects
- Hippocampus/pathology
- Humans
- Kainic Acid/toxicity
- Ligands
- Male
- Neurons/drug effects
- Neurons/metabolism
- Neurons/pathology
- Peptide Fragments/pharmacology
- Protein Binding
- Rats
- Rats, Sprague-Dawley
- Receptor, Galanin, Type 1/agonists
- Receptor, Galanin, Type 1/metabolism
- Receptor, Galanin, Type 2/agonists
- Receptor, Galanin, Type 2/metabolism
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Affiliation(s)
- Kristin Webling
- Department of Neurochemistry, Stockholm University, Svante Arrheniusv. 16B, SE-10691, Stockholm, Sweden.
| | - Jessica L Groves-Chapman
- Neuroscience Program, Biomedical and Health Science Institute, Department of Psychology, The University of Georgia, Athens, GA, USA
| | - Johan Runesson
- Department of Neurochemistry, Stockholm University, Svante Arrheniusv. 16B, SE-10691, Stockholm, Sweden
| | - Indrek Saar
- Institute of technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia
| | - Andreas Lang
- Research Program for Receptorbiochemistry and Tumormetabolism, Laura Bassi Centre of Expertise THERAPEP, Department of Pediatrics/University Hospital Salzburg, Paracelsus Medical University, Müllner Hauptstr. 48, 5020, Salzburg, Austria
| | - Rannar Sillard
- Department of Neurochemistry, Stockholm University, Svante Arrheniusv. 16B, SE-10691, Stockholm, Sweden
| | - Erik Jakovenko
- Department of Neurochemistry, Stockholm University, Svante Arrheniusv. 16B, SE-10691, Stockholm, Sweden
| | - Barbara Kofler
- Research Program for Receptorbiochemistry and Tumormetabolism, Laura Bassi Centre of Expertise THERAPEP, Department of Pediatrics/University Hospital Salzburg, Paracelsus Medical University, Müllner Hauptstr. 48, 5020, Salzburg, Austria
| | - Philip V Holmes
- Neuroscience Program, Biomedical and Health Science Institute, Department of Psychology, The University of Georgia, Athens, GA, USA
| | - Ülo Langel
- Department of Neurochemistry, Stockholm University, Svante Arrheniusv. 16B, SE-10691, Stockholm, Sweden; Institute of technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia
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17
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Reyes-Alcaraz A, Lee YN, Son GH, Kim NH, Kim DK, Yun S, Kim DH, Hwang JI, Seong JY. Development of Spexin-based Human Galanin Receptor Type II-Specific Agonists with Increased Stability in Serum and Anxiolytic Effect in Mice. Sci Rep 2016; 6:21453. [PMID: 26907960 PMCID: PMC4764904 DOI: 10.1038/srep21453] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 01/22/2016] [Indexed: 01/16/2023] Open
Abstract
The novel neuropeptide spexin (SPX) was discovered to activate galanin receptor 2 (GALR2) and 3 (GALR3) but not galanin receptor 1 (GALR1). Although GALR2 is known to display a function, particularly in anxiety, depression, and appetite regulation, the further determination of its function would benefit from a more stable and selective agonist that acts only at GALR2. In the present study, we developed a GALR2-specific agonist with increased stability in serum. As galanin (GAL) showed a low affinity to GALR3, the residues in SPX were replaced with those in GAL, revealing that particular mutations such as Gln5 → Asn, Met7 → Ala, Lys11 → Phe, and Ala13 → Pro significantly decreased potencies toward GALR3 but not toward GALR2. Quadruple (Qu) mutation of these residues still retained potency to GALR2 but totally abolished the potency to both GALR3 and GALR1. The first amino acid modifications or D-Asn1 substitution significantly increased the stability when they are incubated in 100% fetal bovine serum. Intracerebroventricular administration of the mutant peptide with D-Asn1 and quadruple substitution (dN1-Qu) exhibited an anxiolytic effect in mice. Taken together, the GALR2-specific agonist with increased stability can greatly help delineation of GALR2-mediated functions and be very useful for treatments of anxiety disorder.
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Affiliation(s)
| | - Yoo-Na Lee
- Graduate School of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Gi Hoon Son
- Graduate School of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Nam Hoon Kim
- Graduate School of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Dong-Kyu Kim
- Graduate School of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Seongsik Yun
- Graduate School of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Dong-Hoon Kim
- Graduate School of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Jong-Ik Hwang
- Graduate School of Medicine, Korea University, Seoul 02841, Republic of Korea
| | - Jae Young Seong
- Graduate School of Medicine, Korea University, Seoul 02841, Republic of Korea
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18
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Weinshenker D, Holmes PV. Regulation of neurological and neuropsychiatric phenotypes by locus coeruleus-derived galanin. Brain Res 2015; 1641:320-37. [PMID: 26607256 DOI: 10.1016/j.brainres.2015.11.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 10/27/2015] [Accepted: 11/12/2015] [Indexed: 12/28/2022]
Abstract
Decades of research confirm that noradrenergic locus coeruleus (LC) neurons are essential for arousal, attention, motivation, and stress responses. While most studies on LC transmission focused unsurprisingly on norepinephrine (NE), adrenergic signaling cannot account for all the consequences of LC activation. Galanin coexists with NE in the vast majority of LC neurons, yet the precise function of this neuropeptide has proved to be surprisingly elusive given our solid understanding of the LC system. To elucidate the contribution of galanin to LC physiology, here we briefly summarize the nature of stimuli that drive LC activity from a neuroanatomical perspective. We go on to describe the LC pathways in which galanin most likely exerts its effects on behavior, with a focus on addiction, depression, epilepsy, stress, and Alzheimer׳s disease. We propose a model in which LC-derived galanin has two distinct functions: as a neuromodulator, primarily acting via the galanin 1 receptor (GAL1), and as a trophic factor, primarily acting via galanin receptor 2 (GAL2). Finally, we discuss how the recent advances in neuropeptide detection, optogenetics and chemical genetics, and galanin receptor pharmacology can be harnessed to identify the roles of LC-derived galanin definitively. This article is part of a Special Issue entitled SI: Noradrenergic System.
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Affiliation(s)
- David Weinshenker
- Department of Human Genetics, Emory University School of Medicine, 615 Michael St., Whitehead 301, Atlanta, GA 30322, USA.
| | - Philip V Holmes
- Neuroscience Program, Biomedical and Health Sciences Institute and Psychology Department, University of Georgia, Athens, GA 30602, USA.
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19
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Fang P, He B, Shi M, Kong G, Dong X, Zhu Y, Bo P, Zhang Z. The regulative effect of galanin family members on link of energy metabolism and reproduction. Peptides 2015; 71:240-9. [PMID: 26188174 DOI: 10.1016/j.peptides.2015.07.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 06/27/2015] [Accepted: 07/03/2015] [Indexed: 12/22/2022]
Abstract
It is essential for the species survival that an efficient coordination between energy storage and reproduction through endocrine regulation. The neuropeptide galanin, one of the endocrine hormones, can potently coordinate energy metabolism and the activities of hypothalamic-pituitary-gonadal reproductive axis to adjust synthesis and release of metabolic and reproductive hormones in animals and humans. However, few papers have summarized the regulative effect of the galanin family members on the link of energy storage and reproduction as yet. To address this issue, this review attempts to summarize the current information available about the regulative effect of galanin, galanin-like peptide and alarin on the metabolic and reproductive events, with special emphasis on the interactions between galanin and hypothalamic gonadotropin-releasing hormone, pituitary luteinizing hormone and ovarian hormones. This research line will further deepen our understanding of the physiological roles of the galanin family in regulating the link of energy metabolism and reproduction.
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Affiliation(s)
- Penghua Fang
- Department of Physiology, Nanjing University of Chinese Medicine Hanlin College, Taizhou 225300, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225001, China
| | - Biao He
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225001, China
| | - Mingyi Shi
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou 225001, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225001, China
| | - Guimei Kong
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225001, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, China
| | - Xiaoyun Dong
- Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225001, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, China
| | - Yan Zhu
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou 225001, China
| | - Ping Bo
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou 225001, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225001, China.
| | - Zhenwen Zhang
- Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou 225001, China; Jiangsu Key Laboratory of Integrated Traditional Chinese and Western Medicine for Prevention and Treatment of Senile Diseases, Yangzhou University, Yangzhou 225001, China.
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20
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Schrödl F, Kaser-Eichberger A, Trost A, Strohmaier C, Bogner B, Runge C, Bruckner D, Motloch K, Holub B, Kofler B, Reitsamer HA. Distribution of galanin receptors in the human eye. Exp Eye Res 2015; 138:42-51. [PMID: 26122049 DOI: 10.1016/j.exer.2015.06.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 06/15/2015] [Accepted: 06/22/2015] [Indexed: 12/12/2022]
Abstract
The neuropeptide galanin (GAL) is widely distributed within intrinsic and extrinsic sources supplying the eye. It is involved in regulation of the vascular tone, thus important for ocular homeostasis. Since the presence/distribution of its receptors is unknown, we here screen for the presence of the various GAL receptors in the human eye. Meeting the Helsinki-Declaration, human eyes (n = 6; 45-83 years of age, of both sex, post mortem time 10-19 h) were obtained from the cornea bank and prepared for immunohistochemistry against GAL receptors 1-3 (GALR1-GALR3). Over-expressing cell assays served as positive controls and confocal laser-scanning microscopy was used for documentation. Cell assays reliably detected immunoreactivity for GALR1-3 and cross-reactions between antibodies used were not observed. In the cornea, GALR1-3 were detected in basal layers of the epithelium, stroma, endothelium, as well as in adjacent conjunctiva. In the iris, GALR1-3 were detected in iris sphincter and dilator, while iris vessels displayed immunoreactivity for GALR1 and GALR3. In the ciliary body, GALR1 was exclusively found in the non-pigmented epithelium while GALR3 was detected in the ciliary muscle and vessels. In the retina, GALR1 was present in fibers of the IPL, OPL, NFL, many cells of the INL and few cells of the ONL. GALR2 and GALR3 were present in few neurons of the INL, while GALR2 was also found surrounding retinal vessels. RPE displayed weak immunoreactivity for GALR2 but intense immunoreactivity for GALR3. In the choroid, GALR1-3 were detectable in intrinsic choroidal neurons and nerve fibers of the choroidal stroma, and all three receptors were detected surrounding choroidal blood vessels, while the choriocapillaris was immunoreactive for GALR3 only. This is the first report of the various GALRs in the human eye. While the presence of GALRs in cornea and conjunctiva might be relevant for wound healing or inflammatory processes, the detection in iris vessels (GALR1, 2) and choroidal vessels (GALR1-3) highlights the role of GAL in vessel dynamics. Presence of GALR1 in ciliary body epithelium and GALR3 in ciliary vessels indicates involvement in aqueous humor production, whereas retinal GALR distribution might contribute to signal transduction.
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Affiliation(s)
- Falk Schrödl
- University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria; Department of Anatomy, Paracelsus Medical University, Strubergasse 21, 5020 Salzburg, Austria.
| | - Alexandra Kaser-Eichberger
- University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria
| | - Andrea Trost
- University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria
| | - Clemens Strohmaier
- University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria
| | - Barbara Bogner
- University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria
| | - Christian Runge
- University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria
| | - Daniela Bruckner
- University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria
| | - Karolina Motloch
- University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria
| | - Barbara Holub
- Laura-Bassi Centre of Expertise, THERAPEP, Department of Pediatrics, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria
| | - Barbara Kofler
- Laura-Bassi Centre of Expertise, THERAPEP, Department of Pediatrics, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria
| | - Herbert A Reitsamer
- University Clinic of Ophthalmology and Optometry, Research Program for Ophthalmology and Glaucoma Research, Paracelsus Medical University, Muellner Hauptstrasse 48, 5020 Salzburg, Austria
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21
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Lang R, Gundlach AL, Holmes FE, Hobson SA, Wynick D, Hökfelt T, Kofler B. Physiology, signaling, and pharmacology of galanin peptides and receptors: three decades of emerging diversity. Pharmacol Rev 2015; 67:118-75. [PMID: 25428932 DOI: 10.1124/pr.112.006536] [Citation(s) in RCA: 228] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Galanin was first identified 30 years ago as a "classic neuropeptide," with actions primarily as a modulator of neurotransmission in the brain and peripheral nervous system. Other structurally-related peptides-galanin-like peptide and alarin-with diverse biologic actions in brain and other tissues have since been identified, although, unlike galanin, their cognate receptors are currently unknown. Over the last two decades, in addition to many neuronal actions, a number of nonneuronal actions of galanin and other galanin family peptides have been described. These include actions associated with neural stem cells, nonneuronal cells in the brain such as glia, endocrine functions, effects on metabolism, energy homeostasis, and paracrine effects in bone. Substantial new data also indicate an emerging role for galanin in innate immunity, inflammation, and cancer. Galanin has been shown to regulate its numerous physiologic and pathophysiological processes through interactions with three G protein-coupled receptors, GAL1, GAL2, and GAL3, and signaling via multiple transduction pathways, including inhibition of cAMP/PKA (GAL1, GAL3) and stimulation of phospholipase C (GAL2). In this review, we emphasize the importance of novel galanin receptor-specific agonists and antagonists. Also, other approaches, including new transgenic mouse lines (such as a recently characterized GAL3 knockout mouse) represent, in combination with viral-based techniques, critical tools required to better evaluate galanin system physiology. These in turn will help identify potential targets of the galanin/galanin-receptor systems in a diverse range of human diseases, including pain, mood disorders, epilepsy, neurodegenerative conditions, diabetes, and cancer.
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Affiliation(s)
- Roland Lang
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Andrew L Gundlach
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Fiona E Holmes
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Sally A Hobson
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - David Wynick
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Tomas Hökfelt
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
| | - Barbara Kofler
- Department of Dermatology (R.L.) and Laura Bassi Centre of Expertise, Department of Pediatrics (B.K.), Paracelsus Private Medical University, Salzburg, Austria; The Florey Institute of Neuroscience and Mental Health, and Florey Department of Neuroscience and Mental Health, The University of Melbourne, Melbourne, Victoria, Australia (A.L.G.); Schools of Physiology and Pharmacology and Clinical Sciences, Bristol University, Bristol, United Kingdom (F.E.H., S.A.H., D.W.); and Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden (T.H.)
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Fang P, Shi M, Yu M, Guo L, Bo P, Zhang Z. Endogenous peptides as risk markers to assess the development of insulin resistance. Peptides 2014; 51:9-14. [PMID: 24184593 DOI: 10.1016/j.peptides.2013.10.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/19/2013] [Accepted: 10/21/2013] [Indexed: 01/15/2023]
Abstract
Insulin resistance, the reciprocal of insulin sensitivity, is known to be a characteristic of type 2 diabetes mellitus, and is regarded as an important mechanism in the pathogenesis. The hallmark of insulin resistance is a gradual break-down of insulin-regulative glucose uptake by muscle and adipose tissues in subjects. Insulin resistance is increasingly estimated in various disease conditions to examine and assess their etiology, pathogenesis and consequences. Although our understanding of insulin resistance has tremendously been improved in recent years, certain aspects of its estimation and etiology still remain elusive to clinicians and researchers. There are numerous factors involved in pathogenesis and mechanisms of insulin resistance. Recent studies have provided compelling clues about some peptides and proteins, including galanin, galanin-like peptide, ghrelin, adiponectin, retinol binding protein 4 (RBP4) and CRP, which may be used to simplify and to improve the determination of insulin resistance. And alterations of these peptide levels may be recognized as risk markers of developing insulin resistance and type 2 diabetes mellitus. This review examines the updated information for these peptides, highlighting the relations between these peptide levels and insulin resistance. The plasma high ghrelin, RBP4 and CRP as well as low galanin, GALP and adiponectin levels may be taken as the markers of deteriorating insulin resistance. An increase in the knowledge of these marker proteins and peptides will help us correctly diagnose and alleviate insulin resistance in clinic and study.
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Affiliation(s)
- Penghua Fang
- Research Institution of Combining Chinese Traditional and Western Medicine, Medical College, Yangzhou University, Yangzhou, Jiangsu 225001, China; Department of Physiology, Nanjing University of Chinese Medicine Hanlin College, Taizhou, Jiangsu 225300, China
| | - Mingyi Shi
- Research Institution of Combining Chinese Traditional and Western Medicine, Medical College, Yangzhou University, Yangzhou, Jiangsu 225001, China
| | - Mei Yu
- Taizhou Hospital of Traditional Chinese Medicine, Nanjing University of Chinese Medicine, Taizhou, Jiangsu 225300, China
| | - Lili Guo
- Research Institution of Combining Chinese Traditional and Western Medicine, Medical College, Yangzhou University, Yangzhou, Jiangsu 225001, China
| | - Ping Bo
- Research Institution of Combining Chinese Traditional and Western Medicine, Medical College, Yangzhou University, Yangzhou, Jiangsu 225001, China
| | - Zhenwen Zhang
- Research Institution of Combining Chinese Traditional and Western Medicine, Medical College, Yangzhou University, Yangzhou, Jiangsu 225001, China; Department of Endocrinology, Clinical Medical College, Yangzhou University, Yangzhou, Jiangsu 225001, China.
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23
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Kong Q, Yu LC. Antinociceptive effects induced by intra-periaqueductal grey injection of the galanin receptor 1 agonist M617 in rats with morphine tolerance. Neurosci Lett 2013; 550:125-8. [DOI: 10.1016/j.neulet.2013.06.059] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Revised: 06/10/2013] [Accepted: 06/25/2013] [Indexed: 12/23/2022]
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24
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Saar I, Lahe J, Langel K, Runesson J, Webling K, Järv J, Rytkönen J, Närvänen A, Bartfai T, Kurrikoff K, Langel Ü. Novel systemically active galanin receptor 2 ligands in depression-like behavior. J Neurochem 2013; 127:114-23. [PMID: 23600864 DOI: 10.1111/jnc.12274] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 03/31/2013] [Accepted: 03/31/2013] [Indexed: 11/30/2022]
Abstract
Neuropeptide galanin and its three G-protein coupled receptors, galanin receptor type 1-galanin receptor type 3 (GalR1-GalR3), are involved in the regulation of numerous physiological and disease processes, and thus represent tremendous potential in neuroscience research and novel drug lead development. One of the areas where galanin is involved is depression. Previous studies have suggested that activation of GalR2 leads to attenuation of depression-like behavior. Unfortunately, lack of in vivo usable subtype specific ligands hinders testing the role of galanin in depression mechanisms. In this article, we utilize an approach of increasing in vivo usability of peptide-based ligands, acting upon CNS. Thus, we have synthesized a series of novel systemically active galanin analogs, with modest preferential binding toward GalR2. We have shown that specific chemical modifications to the galanin backbone increase brain levels upon i.v. injection of the peptides. Several of the new peptides, similar to a common clinically used antidepressant medication imipramine, exerted antidepressant-like effect in forced swim test, a mouse model of depression, at a surprisingly low dose range (< 0.5 mg/kg). We chose one of the peptides, J18, for more thorough study, and showed its efficacy also in another mouse depression model (tail suspension test), and demonstrated that its antidepressant-like effect upon i.v. administration can be blocked by i.c.v. galanin receptor antagonist M35. The effect of the J18 was also abolished in GalR2KO animals. All this suggests that systemically administered peptide analog J18 exerts its biological effect through activation of GalR2 in the brain. The novel galanin analogs represent potential drug leads and a novel pharmaceutical intervention for depression.
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Affiliation(s)
- Indrek Saar
- Institute of Technology, University of Tartu, Tartu, Estonia; Department of Neurochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
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25
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Bovell DL, Holub BS, Odusanwo O, Brodowicz B, Rauch I, Kofler B, Lang R. Galanin is a modulator of eccrine sweat gland secretion. Exp Dermatol 2013; 22:141-3. [DOI: 10.1111/exd.12067] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2012] [Indexed: 01/30/2023]
Affiliation(s)
- Douglas L. Bovell
- Department of Biological and Biomedical Science; Glasgow Caledonian University; Glasgow; UK
| | - Barbara S. Holub
- Laura Bassi Centre of Expertise THERAPEP; Research Program for Receptor Biochemistry and Tumor Metabolism; Department of Pediatrics; Paracelsus Medical University Salzburg; Salzburg; Austria
| | - Olutayo Odusanwo
- Department of Biological and Biomedical Science; Glasgow Caledonian University; Glasgow; UK
| | - Bernhard Brodowicz
- Laura Bassi Centre of Expertise THERAPEP; Research Program for Receptor Biochemistry and Tumor Metabolism; Department of Pediatrics; Paracelsus Medical University Salzburg; Salzburg; Austria
| | - Isabella Rauch
- Laura Bassi Centre of Expertise THERAPEP; Research Program for Receptor Biochemistry and Tumor Metabolism; Department of Pediatrics; Paracelsus Medical University Salzburg; Salzburg; Austria
| | - Barbara Kofler
- Laura Bassi Centre of Expertise THERAPEP; Research Program for Receptor Biochemistry and Tumor Metabolism; Department of Pediatrics; Paracelsus Medical University Salzburg; Salzburg; Austria
| | - Roland Lang
- Department of Dermatology; Paracelsus Medical University Salzburg; Salzburg; Austria
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26
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Jurkowski W, Yazdi S, Elofsson A. Ligand binding properties of human galanin receptors. Mol Membr Biol 2012; 30:206-16. [DOI: 10.3109/09687688.2012.750384] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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27
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Saar I, Runesson J, Järv J, Kurrikoff K, Langel Ü. Novel Galanin Receptor Subtype Specific Ligand in Depression Like Behavior. Neurochem Res 2012. [DOI: 10.1007/s11064-012-0933-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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28
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Fang P, Yu M, Shi M, Zhang Z, Sui Y, Guo L, Bo P. Galanin peptide family as a modulating target for contribution to metabolic syndrome. Gen Comp Endocrinol 2012; 179:115-20. [PMID: 22909974 DOI: 10.1016/j.ygcen.2012.07.029] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 07/25/2012] [Accepted: 07/27/2012] [Indexed: 12/23/2022]
Abstract
Metabolic syndrome (MetS) is defined as abdominal central obesity, atherogenic dyslipidemia, insulin resistance, glucose intolerance and hypertension. The rapid increasing prevalence of MetS and the consequent diseases, such as type 2 diabetes mellitus and cardiovascular disorder, are becoming a global epidemic health problem. Despite considerable research into the etiology of this complex disease, the precise mechanism underlying MetS and the association of this complex disease with the development of type 2 diabetes mellitus and increased cardiovascular disease remains elusive. Therefore, researchers continue to actively search for new MetS treatments. Recent animal studies have indicated that the galanin peptide family of peptides may increase food intake, glucose intolerance, fat preference and the risk for obesity and dyslipidemia while decreasing insulin resistance and blood pressure, which diminishes the probability of type 2 diabetes mellitus and hypertension. To date, however, few papers have summarized the role of the galanin peptide family in modulating MetS. Through a summary of available papers and our recent studies, this study reviews the updated evidences of the effect that the galanin peptide family has on the clustering of MetS components, including obesity, dyslipidemia, insulin resistance and hypertension. This line of research will further deepen our understanding of the relationship between the galanin peptide family and the mechanisms underlying MetS, which will help develop new therapeutic strategies for this complex disease.
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Affiliation(s)
- Penghua Fang
- Department of Physiology, Hanlin College, Nanjing University of Chinese Medicine, Taizhou, Jiangsu 225300, China
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29
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Fang P, Yu M, Guo L, Bo P, Zhang Z, Shi M. Galanin and its receptors: a novel strategy for appetite control and obesity therapy. Peptides 2012; 36:331-9. [PMID: 22664322 DOI: 10.1016/j.peptides.2012.05.016] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 05/24/2012] [Accepted: 05/24/2012] [Indexed: 12/14/2022]
Abstract
The rapid increase in the prevalence of overweight and obesity is becoming an important health problem. Overweight and obesity may cause several metabolic complications, including type 2 diabetes mellitus, hyperlipidemia, high cholesterol, coronary artery disease as well as hypertension. Prevention and treatment of obesity will benefit the treatment of these related diseases. Current strategies for treatment of obesity are not adequately effective and are frequently companied with many side effects. Thus, new ways to treat obesity are urgently needed. Galanin is undoubtedly involved in the regulation of food intake and body weight. The aim of this review is to provide up-to-date knowledge concerning the roles of central and peripheral galanin as well as its receptors in the regulation of metabolism, obesity and appetite. We also highlight the mechanisms of galanin and its receptors in experimental obesity, trying to establish a novel anti-obesity strategy.
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Affiliation(s)
- Penghua Fang
- Department of Physiology, Yangzhou University, Yangzhou, Jiangsu, China
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30
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Holub B, Kloepper J, Tóth B, Bíro T, Kofler B, Paus R. The neuropeptide galanin is a novel inhibitor of human hair growth. Br J Dermatol 2012; 167:10-6. [DOI: 10.1111/j.1365-2133.2012.10890.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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31
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Webling KEB, Runesson J, Bartfai T, Langel Ü. Galanin receptors and ligands. Front Endocrinol (Lausanne) 2012; 3:146. [PMID: 23233848 PMCID: PMC3516677 DOI: 10.3389/fendo.2012.00146] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 11/08/2012] [Indexed: 12/13/2022] Open
Abstract
The neuropeptide galanin was first discovered 30 years ago. Today, the galanin family consists of galanin, galanin-like peptide (GALP), galanin-message associated peptide (GMAP), and alarin and this family has been shown to be involved in a wide variety of biological and pathological functions. The effect is mediated through three GPCR subtypes, GalR1-3. The limited number of specific ligands to the galanin receptor subtypes has hindered the understanding of the individual effects of each receptor subtype. This review aims to summarize the current data of the importance of the galanin receptor subtypes and receptor subtype specific agonists and antagonists and their involvement in different biological and pathological functions.
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Affiliation(s)
- Kristin E. B. Webling
- Department of Neurochemistry, Arrhenius Laboratories for Natural Science, Stockholm UniversityStockholm, Sweden
- *Correspondence: Kristin E. B. Webling, Department of Neurochemistry, Arrhenius Laboratories for Natural Science, Stockholm University, Svante Arrheniusv. 21A, 10691 Stockholm, Sweden. e-mail:
| | - Johan Runesson
- Department of Neurochemistry, Arrhenius Laboratories for Natural Science, Stockholm UniversityStockholm, Sweden
| | - Tamas Bartfai
- Molecular and Integrative Neurosciences Department, The Scripps Research InstituteLa Jolla, CA, USA
| | - Ülo Langel
- Department of Neurochemistry, Arrhenius Laboratories for Natural Science, Stockholm UniversityStockholm, Sweden
- Institute of Technology, University of TartuTartu, Estonia
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32
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Involvement of protein kinase C in the galanin-induced antinociception in the brain of rats. Neurosci Lett 2011; 497:60-3. [DOI: 10.1016/j.neulet.2011.04.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 04/10/2011] [Accepted: 04/12/2011] [Indexed: 12/17/2022]
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33
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Novel galanin receptor subtype specific ligands in feeding regulation. Neurochem Int 2011; 58:714-20. [DOI: 10.1016/j.neuint.2011.02.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 01/31/2011] [Accepted: 02/10/2011] [Indexed: 11/17/2022]
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34
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Robertson CR, Flynn SP, White HS, Bulaj G. Anticonvulsant neuropeptides as drug leads for neurological diseases. Nat Prod Rep 2011; 28:741-62. [PMID: 21340067 DOI: 10.1039/c0np00048e] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Anticonvulsant neuropeptides are best known for their ability to suppress seizures and modulate pain pathways. Galanin, neuropeptide Y, somatostatin, neurotensin, dynorphin, among others, have been validated as potential first-in-class anti-epileptic or/and analgesic compounds in animal models of epilepsy and pain, but their therapeutic potential extends to other neurological indications, including neurodegenerative and psychatric disorders. Disease-modifying properties of neuropeptides make them even more attractive templates for developing new-generation neurotherapeutics. Arguably, efforts to transform this class of neuropeptides into drugs have been limited compared to those for other bioactive peptides. Key challenges in developing neuropeptide-based anticonvulsants are: to engineer optimal receptor-subtype selectivity, to improve metabolic stability and to enhance their bioavailability, including penetration across the blood–brain barrier (BBB). Here, we summarize advances toward developing systemically active and CNS-penetrant neuropeptide analogs. Two main objectives of this review are: (1) to provide an overview of structural and pharmacological properties for selected anticonvulsant neuropeptides and their analogs and (2) to encourage broader efforts to convert these endogenous natural products into drug leads for pain, epilepsy and other neurological diseases.
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Affiliation(s)
- Charles R Robertson
- College of Pharmacy, Department of Medicinal Chemistry, 421 Wakara Way, STE. 360 Salt Lake City, UT 84108, USA
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35
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Holm L, Theodorsson E, Hökfelt T, Theodorsson A. Effects of intracerebroventricular galanin or a galanin receptor 2/3 agonist on the lesion induced by transient occlusion of the middle cerebral artery in female rats. Neuropeptides 2011; 45:17-23. [PMID: 20974494 DOI: 10.1016/j.npep.2010.09.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 09/27/2010] [Accepted: 09/28/2010] [Indexed: 11/25/2022]
Abstract
Several studies have shown that injury to the central and peripheral nervous system can increase expression of galanin, a 29 amino acid neuropeptide. Moreover, there is evidence that galanin, especially through its galanin receptor 2 (GalR2) receptor, plays a neuroprotective role in different injury models. However, direct studies of a possible neuroprotective effect of galanin in experimental stroke models are lacking. Galanin, a GalR2/3 agonist or artificial CSF was continuously infused intracerebroventricularly (i.c.v.) in naïve female rats after a 60min transient and focal occlusion of the middle cerebral artery. The animals were sacrificed, and the ischemic lesion was visualized using 2,3,5-triphenyltetrazolium hydrochloride (TTC) staining. The lesion was 98% larger after i.c.v. administration of the GalR2/3 agonist (2.4nmol/day) seven days after occlusion compared to artificial CSF (p=0.023). No statistically significant differences were found after seven days in the groups treated with galanin in three different concentrations (0.24, 2.4 and 24nmol/day; p=0.939, 0.715 and 0.977, respectively). There was no difference in the size of the ischemic lesions measured after three days in the galanin-treated group (2.4nmol/d) compared to artificial CSF (p=0.925). The present results show, surprisingly, that a GalR2/3 agonist doubled the size of the ischemic lesion. Whether this effect primarily reflects the properties of the current model, species, gender and/or the mode of galanin administration, e.g. causing desensitization, or whether galanin indeed lacks neuroprotective effect of its own, remains to be corroborated.
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Affiliation(s)
- Lovisa Holm
- Department of Clinical and Experimental Medicine/Division of Clinical Chemistry, Linköping University, Linköping, Sweden
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36
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Determining receptor–ligand interaction of human galanin receptor type 3. Neurochem Int 2010; 57:804-11. [DOI: 10.1016/j.neuint.2010.08.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 08/20/2010] [Accepted: 08/25/2010] [Indexed: 11/18/2022]
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37
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GalR2-positive allosteric modulator exhibits anticonvulsant effects in animal models. Proc Natl Acad Sci U S A 2010; 107:15229-34. [PMID: 20660766 DOI: 10.1073/pnas.1008986107] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Galanin receptors type 1 (GalR1) and/or type 2 (GalR2) represent unique pharmacological targets for treatment of seizures and epilepsy. Previous studies have shown that the endogenous peptide ligand galanin exerts powerful anticonvulsant effect through activation of these two G protein-coupled receptors, which are highly expressed in the temporal lobe of rodent brain. Here we report the characterization of a putative GalR2-positive allosteric modulator CYM2503. CYM2503 potentiated the galanin-stimulated IP1 accumulation in HEK293 cells stably expressing GalR2 receptor, whereas it exhibited no detectable affinity for the (125)I galanin-binding site of GalR2 receptor, an effect consistent with that of a positive allosteric modulator. In the rat Li-pilocarpine status epilepticus model, CYM2503, injected intraperitoneally, increased the latency to first electrographic seizure and the latency to first stage 3 behavioral seizure, decreased the latency to the establishment of status epilepticus, and dramatically decreased the mortality. In a Li-pilocarpine seizure model in mice, CYM2503 increased the latency to first electrographic seizure and decreased the total time in seizure. CYM2503 also attenuated electroshock-induced seizures in mice. Thus, CYM2503 provides a starting point for the development of anticonvulsant therapy using the galanin R2 receptor as target.
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38
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Robertson CR, Scholl EA, Pruess TH, Green BR, White HS, Bulaj G. Engineering galanin analogues that discriminate between GalR1 and GalR2 receptor subtypes and exhibit anticonvulsant activity following systemic delivery. J Med Chem 2010; 53:1871-5. [PMID: 20121116 DOI: 10.1021/jm9018349] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Galanin modulates seizures in the brain through two galanin receptor subtypes, GalR1 and GalR2. To generate systemically active galanin receptor ligands that discriminate between GalR1 and GalR2, the GalR1-preferring analogue Gal-B2 (or NAX 5055) was rationally redesigned to yield GalR2-preferring analogues. Systematic truncations of the N-terminal backbone led to [N-Me,des-Sar]Gal-B2, containing N-methyltryptophan. This analogue exhibited 18-fold preference in binding toward GalR2, maintained agonist activity, and exhibited potent anticonvulsant activity in mice following intraperitoneal administration.
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Affiliation(s)
- Charles R Robertson
- Department of Medicinal Chemistry, College of Pharmacy, University of Utah, 421 WakaraWay, Salt Lake City, Utah 84108, USA
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39
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Binding of Chimeric Peptides M617 and M871 to Galanin Receptor Type 3 Reveals Characteristics of Galanin Receptor–Ligand Interaction. Int J Pept Res Ther 2010. [DOI: 10.1007/s10989-009-9197-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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