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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: 218] [Impact Index Per Article: 24.2] [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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Engert S, Wendland JR, Schwab A, Petersen M. Leukemia inhibitory factor differentially regulates capsaicin and heat sensitivity in cultured rat dorsal root ganglion neurons. Neuropeptides 2008; 42:193-7. [PMID: 18258298 DOI: 10.1016/j.npep.2007.12.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 12/21/2007] [Accepted: 12/28/2007] [Indexed: 11/19/2022]
Abstract
Thermal hyperalgesia is one hallmark of neuropathic pain conditions. Although the exact pathophysiological mechanisms remain elusive, nerve growth factor (NGF) and leukemia inhibitory factor (LIF) are considered key mediators. Their local availability or synthesis are altered by nerve damage and, in turn, they entail changes in phenotype of affected neurons. We examined the effects of LIF on capsaicin sensitivity, heat responsiveness, and galanin immunoreactivity in rat dorsal root ganglion neurons cultured for up to 6 days without supplemented NGF. Using double labeling, the proportions of heat-sensitive/galanin-immunoreactive (GAL-IR) and capsaicin-sensitive/GAL-IR neurons were compared over time in culture with galanin immunoreactivity being a marker for nociceptive neurons. The time course of the proportions of neurons responding to heat (44 degrees C) or capsaicin (1 microM) which also were GAL-IR was differently affected by LIF. In the absence of LIF, within the population of heat-sensitive neurons, the proportion of neurons also GAL-IR increased from 17% to 32% between 6h and 1 day in culture to stay at this level. For the capsaicin-sensitive neurons, the proportion of neurons also GAL-IR increased from 10% after 6h to 18% at day 2 and then decreased to 4% at day 4. In contrast, LIF prevented the increase in the proportion of heat-sensitive/GAL-IR neurons and the decrease of capsaicin-sensitive/GAL-IR neurons. The results suggest that LIF partially prevents TRPV-1 downregulation in NGF-deprived nociceptive galaninergic DRG neurons. Furthermore, there is evidence that LIF regulates the expression of a heat receptor distinct from TRPV-1.
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Affiliation(s)
- Sabine Engert
- Department of Obstetrics and Gynecology, University of Würzburg, 97080 Würzburg, Germany
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Thippeswamy T, Haddley K, Corness JD, Howard MR, McKay JS, Beaucourt SM, Pope MD, Murphy D, Morris R, Hökfelt T, Quinn JP. NO-cGMP mediated galanin expression in NGF-deprived or axotomized sensory neurons. J Neurochem 2007; 100:790-801. [PMID: 17263797 DOI: 10.1111/j.1471-4159.2006.04243.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Leukaemia inhibitory factor (LIF) and nerve growth factor (NGF) are well characterized regulators of galanin expression. However, LIF knockout mice containing the rat galanin 5' proximal promoter fragment (- 2546 to + 15 bp) driving luciferase responded to axotomy in the same way as control mice. Also, LIF had no effect on reporter gene expression in vitro, neither in the presence or absence of NGF, suggesting that other factors mediate an axotomy response from the galanin promoter. We then addressed the role of nitric oxide (NO) using NGF-deprived rat dorsal root ganglion (DRG) neuron cultures infected with viral vectors containing the above-mentioned construct, and also studied endogenous galanin expression in axotomized DRG in vivo. Blocking endogenous NO in NGF-deprived DRG cultures suppressed galanin promoter activity. Consistent with this, axotomized/NGF-deprived DRG neurons expressed high levels of neuronal NO synthase (nNOS) and galanin. Further, using pharmacological NOS blockers, or adenoviral vectors expressing dominant-negative either for nNOS or soluble guanylate cyclase in vivo and in vitro, we show that the NO-cGMP pathway induces endogenous galanin in DRG neurons. We propose that both LIF and NO, acting at different promoter regions, are important for the up-regulation of galanin, and for DRG neuron survival and regeneration after axotomy.
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MESH Headings
- Animals
- Axotomy
- Cell Survival/drug effects
- Cell Survival/genetics
- Cells, Cultured
- Cyclic GMP/metabolism
- Galanin/metabolism
- Ganglia, Spinal/cytology
- Ganglia, Spinal/drug effects
- Ganglia, Spinal/metabolism
- Gene Expression Regulation/genetics
- Genes, Reporter/genetics
- Genetic Vectors/genetics
- Leukemia Inhibitory Factor/genetics
- Male
- Mice
- Mice, Knockout
- Nerve Growth Factor/deficiency
- Nerve Regeneration/drug effects
- Nerve Regeneration/genetics
- Neurons, Afferent/cytology
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Nitric Oxide/metabolism
- Nitric Oxide Synthase/metabolism
- Promoter Regions, Genetic/genetics
- Rats
- Rats, Wistar
- Sciatic Neuropathy/genetics
- Sciatic Neuropathy/metabolism
- Sciatic Neuropathy/physiopathology
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Affiliation(s)
- Thimmasettappa Thippeswamy
- Department of Veterinary Preclinical Science, Veterinary Faculty, University of Liverpool, Liverpool, UK.
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McDonald AC, Schuijers JA, Shen PJ, Gundlach AL, Grills BL. Expression of galanin and galanin receptor-1 in normal bone and during fracture repair in the rat. Bone 2003; 33:788-97. [PMID: 14623054 DOI: 10.1016/s8756-3282(03)00244-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The neuropeptide galanin (GAL) has recognized physiological actions in the nervous system and other tissues, but there is no documented evidence of GAL influencing normal or pathological bone metabolism. GAL expression, however, is upregulated in central and peripheral nerves following axotomy and is known to influence neural regeneration. Thus, severance of skeletal-associated nerves during fracture could similarly increase local GAL concentrations and thereby influence fracture healing. The initial aim of this study was therefore to identify the presence of GAL in normal bone and/or fracture callus by assessing the concentration and cellular localization of GAL in intact and/or fractured rat rib, using radioimmunoassay and immunohistochemistry, respectively. Groups of Sprague-Dawley rats (13 weeks old) had their left sixth ribs surgically fractured or underwent sham surgery and then calluses and nonfractured rib samples were analyzed at 1 and 2 weeks postsurgery (n = 5-6 per group). Low (basal) concentrations of GAL were detected in control ribs, whereas at 1 and 2 weeks postfracture, callus samples contained markedly increased levels of peptide ( approximately 32- and 18-fold increase, respectively, relative to controls; P < 0.01), revealing a strong upregulation during bone healing. Plasma GAL concentrations were also increased at 2 weeks postfracture (P < 0.005). In normal (nonfractured) rib, minimal levels of GAL-like immunoreactivity (LI) were present in cortical bone, periosteum, endosteum, and surrounding skeletal muscle. In costal cartilage plates, intense GAL-LI was present in all chondrocytes of the hypertrophic zone and in a population of chondrocytes in the reserve zone. GAL-LI was not present, however, in chondrocytes in the proliferative zone of costal cartilage or skeletal muscle fibers. In fracture callus, levels of GAL-LI were moderate to intense in osteoprogenitor cells and osteoblasts, in some chondrocytes, and in cartilaginous, osseous, and periosteal matrices. Subsequent studies revealed the presence of galanin receptor-1-like immunoreactivity (GALR1-LI) in most cell types shown to contain GAL-LI, although the distribution of GALR1-LI was more extensive in reserve zone chondrocytes than that of GAL-LI; and GALR1-LI also appeared in late proliferative zone chondrocytes of costal cartilage. In summary, GAL concentrations were significantly increased in fracture callus and plasma of rats that underwent rib fracture. In addition, GAL- and GALR1-LI was also detected in specific cells and structures within costal cartilage, bone, and fracture callus. These results strongly implicate GAL in aspects of cartilage growth plate physiology and fracture repair, possibly acting in an autocrine/paracrine fashion via GALR1.
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Affiliation(s)
- Aaron C McDonald
- Department of Human Physiology and Anatomy, School of Human Biosciences, La Trobe University, Victoria 3086, Australia
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Damage-induced neuronal endopeptidase (DINE/ECEL) expression is regulated by leukemia inhibitory factor and deprivation of nerve growth factor in rat sensory ganglia after nerve injury. J Neurosci 2002. [PMID: 12417666 DOI: 10.1523/jneurosci.22-21-09410.2002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Damage-induced neuronal endopeptidase (DINE) is a novel metallopeptidase and is expressed in response to various neuronal injuries. The expression regulation of DINE mRNA in the dorsal root ganglia (DRGs) after sciatic nerve injury is examined. A substantial increase of DINE mRNA expression was observed in relatively small-sized DRG neurons after nerve injury. The expression was observed in isolectin B4-negative and partly TrkA-positive neurons, and the expression profile was fairly similar to that of the neuropeptide galanin. More than 80% of DINE mRNA-positive neurons simultaneously demonstrated galanin immunoreactivity after nerve injury. In cultured DRG, DINE mRNA expression was enhanced by leukemia inhibitory factor (LIF) but not by other growth factors and cytokines. LIF treatment to rat sciatic nerve induced DINE mRNA expression in DRG without nerve injury, and, conversely, the intranerve injection of anti-gp130 antibody after sciatic nerve injury significantly inhibited the upregulation of DINE mRNA in DRG. Furthermore, nerve growth factor (NGF) deprivation, which can induce galanin expression, also enhanced DINE mRNA expression in vitro and in vivo. Both LIF application and NGF deprivation additively enhanced DINE expression in vitro. These results suggest that DINE gene expression is regulated separately by both LIF and NGF deprivation, and this regulation pattern is similar to that of galanin gene expression. Because both DINE and galanin have a neuroprotective function, their simultaneous induction may provide more successful protection for injured sensory neurons.
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Bond BC, Virley DJ, Cairns NJ, Hunter AJ, Moore GBT, Moss SJ, Mudge AW, Walsh FS, Jazin E, Preece P. The quantification of gene expression in an animal model of brain ischaemia using TaqMan real-time RT-PCR. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 106:101-16. [PMID: 12393270 DOI: 10.1016/s0169-328x(02)00417-5] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Expression levels of mRNA are commonly measured as a ratio of test to reference gene. The assumption is that reference genes such as beta-actin or cyclophilin are unaffected by treatment and act as steady-state controls. TaqMan real-time RT-PCR was used to test these assumptions in a rat model of cerebral ischaemia (tMCAO). Following measurement of 24 genes, we show that reference genes in this animal model fail the criteria for steady-state controls. Neuronal loss, glial proliferation and an influx of leukocytes into the lesioned brain result in major disturbance to cell populations. The mRNA for reference genes, as for test genes, reflects these changes. Specific mRNA levels vary according to the choice of reference gene to which they are normalised. In the process of resolving reference gene issues, mRNA increases were discovered for leukaemia inhibitory factor, nestin and galanin in rat brain hemispheres affected by ischaemia. Results are reported for a further 21 genes and mathematical and statistical methods are described that allow in this study fraction-fold changes in mRNA to be detected.
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Affiliation(s)
- Brian C Bond
- Department of Statistical Science, Glaxo SmithKline Pharmaceuticals, Third Avenue, Harlow, Essex CM19 5AW, UK.
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Holmes FE, Mahoney S, King VR, Bacon A, Kerr NC, Pachnis V, Curtis R, Priestley JV, Wynick D. Targeted disruption of the galanin gene reduces the number of sensory neurons and their regenerative capacity. Proc Natl Acad Sci U S A 2000; 97:11563-8. [PMID: 11016970 PMCID: PMC17240 DOI: 10.1073/pnas.210221897] [Citation(s) in RCA: 179] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The neuropeptide galanin is expressed developmentally in the dorsal root ganglion (DRG) and is rapidly up-regulated 120-fold after peripheral nerve section in the adult. Here we report that adult mice carrying a loss-of-function mutation in the galanin gene have a 13% reduction in the number of cells in the DRG associated with a 24% decrease in the percentage of neurons that express substance P. These deficits are associated with a 2.8- and 2.6-fold increase in the number of apoptotic cells in the DRG at postnatal days 3 and 4, respectively. After crush injury to the sciatic nerve, the rate of peripheral nerve regeneration is reduced by 35% with associated long-term functional deficits. Cultured DRG neurons from adult mutant mice demonstrate similar deficits in neurite number and length. These results identify a critical role for galanin in the development and regeneration of sensory neurons.
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Affiliation(s)
- F E Holmes
- Departments of Medicine and Oral and Dental Science, Bristol University, Marlborough Street, Bristol BS2 8HW, United Kingdom
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