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Sgro M, Ray J, Foster E, Mychasiuk R. Making migraine easier to stomach: the role of the gut-brain-immune axis in headache disorders. Eur J Neurol 2023; 30:3605-3621. [PMID: 37329292 DOI: 10.1111/ene.15934] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 05/30/2023] [Accepted: 06/12/2023] [Indexed: 06/19/2023]
Abstract
BACKGROUND AND PURPOSE Headache disorders place a significant burden on the healthcare system, being the leading cause of disability in those under 50 years. Novel studies have interrogated the relationship between headache disorders and gastrointestinal dysfunction, suggesting a link between the gut-brain-immune (GBI) axis and headache pathogenesis. Although the exact mechanisms driving the complex relationship between the GBI axis and headache disorders remain unclear, there is a growing appreciation that a healthy and diverse microbiome is necessary for optimal brain health. METHODS A literature search was performed through multiple reputable databases in search of Q1 journals within the field of headache disorders and gut microbiome research and were critically and appropriately evaluated to investigate and explore the following; the role of the GBI axis in dietary triggers of headache disorders and the evidence indicating that diet can be used to alleviate headache severity and frequency. The relationship between the GBI axis and post-traumatic headache is then synthesized. Finally, the scarcity of literature regarding paediatric headache disorders and the role that the GBI axis plays in mediating the relationship between sex hormones and headache disorders are highlighted. CONCLUSIONS There is potential for novel therapeutic targets for headache disorders if understanding of the GBI axis in their aetiology, pathogenesis and recovery is increased.
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Affiliation(s)
- Marissa Sgro
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
| | - Jason Ray
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Melbourne, Victoria, Australia
- Department of Neurology, Austin Health, Melbourne, Victoria, Australia
| | - Emma Foster
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
- Department of Neurology, Alfred Health, Melbourne, Victoria, Australia
- Department of Neurology, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Richelle Mychasiuk
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, Victoria, Australia
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Christensen J, MacPherson N, Li C, Yamakawa GR, Mychasiuk R. Repeat mild traumatic brain injuries (RmTBI) modify nociception and disrupt orexinergic connectivity within the descending pain pathway. J Headache Pain 2023; 24:72. [PMID: 37316796 DOI: 10.1186/s10194-023-01608-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 06/07/2023] [Indexed: 06/16/2023] Open
Abstract
Repeat mild traumatic brain injuries (RmTBI) result in substantial burden to the public health system given their association with chronic post-injury pathologies, such as chronic pain and post-traumatic headache. Although this may relate to dysfunctional descending pain modulation (DPM), it is uncertain what mechanisms drive changes within this pathway. One possibility is altered orexinergic system functioning, as orexin is a potent anti-nociceptive neuromodulator. Orexin is exclusively produced by the lateral hypothalamus (LH) and receives excitatory innervation from the lateral parabrachial nucleus (lPBN). Therefore, we used neuronal tract-tracing to investigate the relationship between RmTBI and connectivity between lPBN and the LH, as well as orexinergic projections to a key site within the DPM, the periaqueductal gray (PAG). Prior to injury induction, retrograde and anterograde tract-tracing surgery was performed on 70 young-adult male Sprague Dawley rats, targeting the lPBN and PAG. Rodents were then randomly assigned to receive RmTBIs or sham injuries before undergoing testing for anxiety-like behaviour and nociceptive sensitivity. Immunohistochemical analysis identified distinct and co-localized orexin and tract-tracing cell bodies and projections within the LH. The RmTBI group exhibited altered nociception and reduced anxiety as well as a loss of orexin cell bodies and a reduction of hypothalamic projections to the ventrolateral nucleus of the PAG. However, there was no significant effect of injury on neuronal connectivity between the lPBN and orexinergic cell bodies within the LH. Our identification of structural losses and the resulting physiological changes in the orexinergic system following RmTBI begins to clarify acute post-injury mechanistic changes that drive may drive the development of post-traumatic headache and the chronification of pain.
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Affiliation(s)
- Jennaya Christensen
- Department of Neuroscience, Central Clinical School, 99 Commercial Road, VIC, 3004, Melbourne, Australia
| | - Naomi MacPherson
- Department of Neuroscience, Central Clinical School, 99 Commercial Road, VIC, 3004, Melbourne, Australia
| | - Crystal Li
- Department of Neuroscience, Central Clinical School, 99 Commercial Road, VIC, 3004, Melbourne, Australia
| | - Glenn R Yamakawa
- Department of Neuroscience, Central Clinical School, 99 Commercial Road, VIC, 3004, Melbourne, Australia
| | - Richelle Mychasiuk
- Department of Neuroscience, Central Clinical School, 99 Commercial Road, VIC, 3004, Melbourne, Australia.
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3
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Reducha PV, Bömers JP, Edvinsson L, Haanes KA. Rodent behavior following a dural inflammation model with anti-CGRP migraine medication treatment. Front Neurol 2023; 14:1082176. [PMID: 36908624 PMCID: PMC9995475 DOI: 10.3389/fneur.2023.1082176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/07/2023] [Indexed: 02/25/2023] Open
Abstract
Background Migraine is a widespread and prevalent disease with a complex pathophysiology, of which neuroinflammation and increased pain sensitivity have been suggested to be involved. Various studies have investigated the presence of different inflammatory markers in migraineurs and investigated the role of inflammation in inflammatory models with complete Freund's adjuvant (CFA) or inflammatory soup added to the dura mater. Objective The aim of the current study was to examine whether application of CFA to the dura mater would cause behavioral alterations that are migraine relevant. In addition, we investigated the potential mitigating effects of fremanezumab, a CGRP (calcitonin gene-related peptide) specific antibody, following CFA application. Methods Male Sprague-Dawley rats were randomly divided into six groups: fresh (n = 7), fresh + carprofen (n = 6), fresh + anti-CGRP (n = 6), sham (n = 7), CFA (n = 16), CFA + anti-CGRP (n = 8). CFA was applied for 15 min on a 3 × 3 mm clearing of the skull exposing the dura mater of male Sprague-Dawley rats. We applied the Light/Dark box and Open Field test, combined with the electronic von Frey test to evaluate outcomes. Finally, we observed CGRP immunoreactivity in the trigeminal ganglion. Results No differences were observed in the Light/Dark box test. The Open Field test detected behavior differences, notably that sham rats spend less time in the central zone, reared less and groomed more than fresh + carprofen rats. The other groups were not significantly different compared to sham rats, indicating that activation of the TGVS is present in sham surgery and cannot be exacerbated by CFA. However, for the allodynia, we observed specific periorbital sensitization, not observed in the sham animals. This could not be mitigated by fremanezumab, although it clearly reduced the amount of CGRP positive fibers. Conclusion CFA surgically administered to the dura causes periorbital allodynia and increases CGRP positive fibers in the trigeminal ganglion. Fremanezumab does not reduce periorbital allodynia even though it reduces CGRP positive fibers in the TG. Further work is needed to investigate whether CFA administered to the dura could be used as a non-CGRP inflammatory migraine model.
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Affiliation(s)
- Philip V Reducha
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital, Glostrup, Denmark.,Section of Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Jesper P Bömers
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital, Glostrup, Denmark.,Department of Neurosurgery, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark
| | - Lars Edvinsson
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital, Glostrup, Denmark.,Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University Hospital, Lund, Sweden
| | - Kristian A Haanes
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital, Glostrup, Denmark.,Section of Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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Reducha PV, Edvinsson L, Haanes KA. Could Experimental Inflammation Provide Better Understanding of Migraines? Cells 2022; 11:cells11152444. [PMID: 35954288 PMCID: PMC9368653 DOI: 10.3390/cells11152444] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 07/29/2022] [Accepted: 08/04/2022] [Indexed: 11/16/2022] Open
Abstract
Migraines constitute a common neurological and headache disorder affecting around 15% of the world’s population. In addition to other mechanisms, neurogenic neuroinflammation has been proposed to play a part in migraine chronification, which includes peripheral and central sensitization. There is therefore considerable evidence suggesting that inflammation in the intracranial meninges could be a key element in addition to calcitonin gene-related peptide (CGRP), leading to sensitization of trigeminal meningeal nociceptors in migraines. There are several studies that have utilized this approach, with a strong focus on using inflammatory animal models. Data from these studies show that the inflammatory process involves sensitization of trigeminovascular afferent nerve terminals. Further, by applying a wide range of different pharmacological interventions, insight has been gained on the pathways involved. Importantly, we discuss how animal models should be used with care and that it is important to evaluate outcomes in the light of migraine pathology.
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Affiliation(s)
- Philip Victor Reducha
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital, Rigshospitalet Glostrup, 2600 Glostrup, Denmark
- Department of Biology, Section of Cell Biology and Physiology, University of Copenhagen, 1017 Copenhagen, Denmark
| | - Lars Edvinsson
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital, Rigshospitalet Glostrup, 2600 Glostrup, Denmark
- Division of Experimental Vascular Research, Department of Clinical Sciences, Lund University Hospital, 221 00 Lund, Sweden
| | - Kristian Agmund Haanes
- Department of Clinical Experimental Research, Glostrup Research Institute, Copenhagen University Hospital, Rigshospitalet Glostrup, 2600 Glostrup, Denmark
- Department of Biology, Section of Cell Biology and Physiology, University of Copenhagen, 1017 Copenhagen, Denmark
- Correspondence:
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He L, Liu L, Guan S, Zheng X, Ge H, Yin C, Shen Y, Tan M, Wang C, Gao Y, Xiong W. Palmatine alleviates hyperalgesia by inhibiting the expression of calcitonin gene-related peptide in the trigeminal ganglion of rats with chronic constriction injury of the infraorbital nerve. Br J Oral Maxillofac Surg 2020; 58:443-450. [PMID: 32139146 DOI: 10.1016/j.bjoms.2020.01.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 01/31/2020] [Indexed: 12/22/2022]
Abstract
Trigeminal neuralgia is one of the most common of the neuropathic pains, and it can seriously influence patients' quality of life. Calcitonin gene-related peptide (CGRP) is a type of nociceptive neurotransmitter that is expressed in neurons of the trigeminal ganglion and plays a major part in transmitting pain. The rat model of trigeminal neuralgia was established by causing a chronic constriction injury of the infraorbital nerve (CCI-ION). Male Sprague-Dawley rats (n=24) were randomly divided into a sham control group (sham, n=6), sham-treated with palmatine group (sham+palmatine, n=6), trigeminal nerve model group (TN, n=6), and trigeminal nerve treated with palmatine group (TN+palmatine, n=6). Fifteen days after the operation the mechanical response threshold was decreased in the TN group compared with the sham group. From postoperative day 7 to day 15, the mechanical response threshold in the TN+palmatine group significantly increased compared with the TN group. On postoperative day 15 the results of quantitative polymerase chain reaction (qPCR), immunohistochemical staining, and western blotting showed an obvious increase in expression of CGRP and its receptors, serum concentrations of interleukin-1β (IL-1β), and tumour necrosis factor-α (TNF-α), and phosphorylation of protein kinase C (PKC) in the trigeminal ganglia of the TN group compared with the sham group, but these increases could be down-regulated by treatment with palmatine. Palmatine might therefore have therapeutic potential for the treatment of trigeminal neuralgia by inhibiting the expression of CGRP and its receptors in trigeminal ganglia, suppressing the serum concentrations of IL-1β and TNF-α, and decreasing the phosphorylation of PKC in the trigeminal ganglia of affected rats.
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Affiliation(s)
- L He
- Affiliated Stomatological Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - L Liu
- Affiliated Stomatological Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - S Guan
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, Jiangxi, China
| | - X Zheng
- Queen Mary college of grade 2015, Nanchang University, Nanchang, Jiangxi, China
| | - H Ge
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, Jiangxi, China
| | - C Yin
- Affiliated Stomatological Hospital of Nanchang University, Nanchang, Jiangxi, China
| | - Y Shen
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, Jiangxi, China
| | - M Tan
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, Jiangxi, China
| | - C Wang
- Second Clinic Medical College of Grade 2017, Nanchang University, Nanchang, Jiangxi, China
| | - Y Gao
- Department of Physiology, Basic Medical College, Nanchang University, Nanchang, Jiangxi, China; Jiangxi Provincial Key Laboratory of Autonomic Nervous Function and Disease, Nanchang, Jiangxi, China
| | - W Xiong
- Affiliated Stomatological Hospital of Nanchang University, Nanchang, Jiangxi, China; Jiangxi Provincial Key Laboratory of Oral Biomedicine, Nanchang, Jiangxi, China.
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Andreou AP, Edvinsson L. Mechanisms of migraine as a chronic evolutive condition. J Headache Pain 2019; 20:117. [PMID: 31870279 PMCID: PMC6929435 DOI: 10.1186/s10194-019-1066-0] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 12/03/2019] [Indexed: 12/17/2022] Open
Abstract
Understanding the mechanisms of migraine remains challenging as migraine is not a static disorder, and even in its episodic form migraine remains an "evolutive" chronic condition. Considerable progress has been made in elucidating the pathophysiological mechanisms of migraine, associated genetic factors that may influence susceptibility to the disease, and functional and anatomical changes during the progression of a migraine attack or the transformation of episodic to chronic migraine. Migraine is a life span neurological disorder that follows an evolutive age-dependent change in its prevalence and even clinical presentations. As a disorder, migraine involves recurrent intense head pain and associated unpleasant symptoms. Migraine attacks evolve over different phases with specific neural mechanisms and symptoms being involved during each phase. In some patients, migraine can be transformed into a chronic form with daily or almost daily headaches. The mechanisms behind this evolutive process remain unknown, but genetic and epigenetic factors, inflammatory processes and central sensitization may play an important role.
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Affiliation(s)
- Anna P Andreou
- Headache Research, Wolfson CARD, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
- The Headache Centre, Guy's and St Thomas', NHS Foundation Trust, London, UK.
| | - Lars Edvinsson
- Department of Medicine, Lund University, 22185, Lund, Sweden
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7
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Edvinsson L, Haanes KA, Warfvinge K. Does inflammation have a role in migraine? Nat Rev Neurol 2019; 15:483-490. [DOI: 10.1038/s41582-019-0216-y] [Citation(s) in RCA: 126] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/14/2019] [Indexed: 01/13/2023]
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Effects of NSAIDs on the Release of Calcitonin Gene-Related Peptide and Prostaglandin E 2 from Rat Trigeminal Ganglia. Mediators Inflamm 2017; 2017:9547056. [PMID: 29209105 PMCID: PMC5676472 DOI: 10.1155/2017/9547056] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 09/26/2017] [Indexed: 11/17/2022] Open
Abstract
Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently used to treat migraine, but the mechanisms of their effects in this pathology are not fully elucidated. The trigeminal ganglia and calcitonin gene-related peptide (CGRP) have been implicated in the pathophysiology of migraine. The release of CGRP and prostaglandin E2 (PGE2) from freshly isolated rat trigeminal ganglia was evaluated after oral administration of nimesulide, etoricoxib, and ketoprofen, NSAIDs with different pharmacological features. Thirty minutes after oral administration, nimesulide, 10 mg/Kg, decreased the GCRP release induced by an inflammatory soup, while the other NSAIDs were ineffective at this point in time. Two hours after oral nimesulide (5 and 10 mg/Kg) and ketoprofen (10 mg/Kg), but not of etoricoxib, a significant decrease in the CGRP release was observed. All drugs reduced PGE2, although with some differences in timing and doses, and the action on CGRP does not seem to be related to PGE2 inhibition. The reduction of CGRP release from rat trigeminal ganglia after nimesulide and ketoprofen may help to explain the mechanism of action of NSAIDs in migraine. Since at 30 minutes only nimesulide was effective in reducing CGRP release, these results suggest that this NSAID may exert a particularly rapid effect in patients with migraine.
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9
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Wang X, Hu R, Liang J, Li Z, Sun W, Pan X. 5-HT7 Receptors Are Not Involved in Neuropeptide Release in Primary Cultured Rat Trigeminal Ganglion Neurons. J Mol Neurosci 2016; 59:251-9. [PMID: 26892478 DOI: 10.1007/s12031-016-0727-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Accepted: 01/26/2016] [Indexed: 12/20/2022]
Abstract
Migraine is a common but complex neurological disorder. Its precise mechanisms are not fully understood. Increasing indirect evidence indicates that 5-HT7 receptors may be involved; however, their role remains unknown. Our previous in vivo study showed that selective blockade of 5-HT7 receptors caused decreased serum levels of calcitonin gene-related peptide (CGRP) in the external jugular vein following electrical stimulation of the trigeminal ganglion (TG) in an animal model of migraine. In the present study, we used an in vitro model of cultured TG cells to further investigate whether 5-HT7 receptors are directly responsible for the release of CGRP and substance P from TG neurons. We stimulated rat primary cultured TG neurons with capsaicin or potassium chloride (KCl) to mimic neurogenic inflammation, resulting in release of CGRP and substance P. 5-HT7 receptors were abundantly expressed in TG neurons. Greater than 93 % of 5-HT7 receptor-positive neurons co-expressed CGRP and 56 % co-expressed substance P. Both the capsaicin- and KCl-induced release of CGRP and substance P were unaffected by pretreatment of cultured TG cells with the selective 5-HT7 receptor agonist AS19 and antagonist SB269970. This study demonstrates for the first time that 5-HT7 receptors are abundantly co-expressed with CGRP and substance P in rat primary TG neurons and suggests that they are not responsible for the release of CGRP and substance P from cultured TG neurons evoked by capsaicin or KCl.
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Affiliation(s)
- Xiaojuan Wang
- Department of Neurology, Guangzhou First People's Hospital, Affiliated to Guangzhou Medical University, No. 1 Panfu Road, Guangzhou, 510180, China
| | - Rong Hu
- Department of Neurology, Guangzhou First People's Hospital, Affiliated to Guangzhou Medical University, No. 1 Panfu Road, Guangzhou, 510180, China
| | - Jianbo Liang
- Department of Clinical Laboratory, The First Affiliated Hospital, Sun Yat-sen University, No. 58 Zhongshan 2nd Road, Guangzhou, 510080, China
| | - Ze Li
- Department of Neurology, Guangzhou First People's Hospital, Affiliated to Guangzhou Medical University, No. 1 Panfu Road, Guangzhou, 510180, China
| | - Weiwen Sun
- Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Institute of Neurosciences and the Second Affiliated Hospital of Guangzhou Medical University, No. 250 Changgang Dong Road, Guangzhou, 510260, China
| | - Xiaoping Pan
- Department of Neurology, Guangzhou First People's Hospital, Affiliated to Guangzhou Medical University, No. 1 Panfu Road, Guangzhou, 510180, China.
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Sághy É, Payrits M, Helyes Z, Reglődi D, Bánki E, Tóth G, Couvineau A, Szőke É. Stimulatory effect of pituitary adenylate cyclase-activating polypeptide 6-38, M65 and vasoactive intestinal polypeptide 6-28 on trigeminal sensory neurons. Neuroscience 2015; 308:144-56. [PMID: 26321242 DOI: 10.1016/j.neuroscience.2015.08.043] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Revised: 07/31/2015] [Accepted: 08/20/2015] [Indexed: 02/08/2023]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) acts on G protein-coupled receptors: the specific PAC1 and VPAC1/VPAC2 receptors. PACAP6-38 was described as a potent PAC1/VPAC2 antagonist in several models, but recent studies reported its agonistic behaviors proposing novel receptorial mechanisms. Since PACAP in migraine is an important research tool, we investigated the effect of PACAP and its peptide fragments on trigeminal primary sensory neurons. Effect of the peptides was studied with ratiometric Ca-imaging technique using the fluorescent indicator fura-2 AM on primary cultures of rat and mouse trigeminal ganglia (TRGs) neurons. Specificity testing was performed on PAC1, VPAC1 and VPAC2 receptor-expressing cell lines with both fluorescent and radioactive Ca-uptake methods. Slowly increasing intracellular free calcium concentration [Ca(2+)]i was detected after PACAP1-38, PACAP1-27, vasoactive intestinal polypeptide (VIP) and the selective PAC1 receptor agonist maxadilan administration on TRG neurons, but interestingly, PACAP6-38, VIP6-28 and the PAC1 receptor antagonist M65 also caused similar activation. The VPAC2 receptor agonist BAY 55-9837 induced similar activation, while the VPAC1 receptor agonist Ala(11,22,28)VIP had no significant effect on [Ca(2+)]i. It was proven that the Ca(2+)-influx originated from intracellular stores using radioactive calcium-45 uptake experiment and Ca-free solution. On the specific receptor-expressing cell lines the antagonists inhibited the stimulating actions of the respective agonists, but had no effects by themselves. PACAP6-38, M65 and VIP6-28, which were described as antagonists in numerous studies in several model systems, act as agonists on TRG primary sensory neurons. Currently unknown receptors or splice variants linked to distinct signal transduction pathways might explain these differences.
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MESH Headings
- Animals
- CHO Cells
- Calcium/metabolism
- Cells, Cultured
- Cricetulus
- Humans
- Insect Proteins/pharmacology
- Mice
- Peptide Fragments/pharmacology
- Pituitary Adenylate Cyclase-Activating Polypeptide/pharmacology
- Rats, Wistar
- Receptors, Vasoactive Intestinal Peptide, Type II/antagonists & inhibitors
- Receptors, Vasoactive Intestinal Peptide, Type II/metabolism
- Receptors, Vasoactive Intestinal Polypeptide, Type I/agonists
- Receptors, Vasoactive Intestinal Polypeptide, Type I/metabolism
- Sensory Receptor Cells/drug effects
- Sensory Receptor Cells/physiology
- Sensory System Agents/pharmacology
- TRPV Cation Channels/metabolism
- Trigeminal Ganglion/drug effects
- Trigeminal Ganglion/physiology
- Vasoactive Intestinal Peptide/pharmacology
- Voltage-Sensitive Dye Imaging
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Affiliation(s)
- É Sághy
- Department of Pharmacology and Pharmacotherapy, MTA-PTE Chronic Pain Research Group, Szentágothai Research Center, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary.
| | - M Payrits
- Department of Pharmacology and Pharmacotherapy, MTA-PTE Chronic Pain Research Group, Szentágothai Research Center, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary.
| | - Zs Helyes
- Department of Pharmacology and Pharmacotherapy, MTA-PTE Chronic Pain Research Group, Szentágothai Research Center, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary.
| | - D Reglődi
- Department of Anatomy, MTA-PTE "Lendület" PACAP Research Team, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary.
| | - E Bánki
- Department of Anatomy, MTA-PTE "Lendület" PACAP Research Team, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary.
| | - G Tóth
- Department of Medical Chemistry, University of Szeged, Szeged-6720, Dugonics Street 13, Hungary.
| | - A Couvineau
- UMR 1149 INSERM/Centre de Recherche sur l'Inflammation, Université Paris Diderot, Faculte de Medecine Paris 7 - Site Bichat, 16 Rue Henri Huchard, 75890 Paris Cedex 18, France.
| | - É Szőke
- Department of Pharmacology and Pharmacotherapy, MTA-PTE Chronic Pain Research Group, Szentágothai Research Center, University of Pécs, Pécs-7624, Szigeti Street 12, Hungary.
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Lundblad C, Haanes KA, Grände G, Edvinsson L. Experimental inflammation following dural application of complete Freund's adjuvant or inflammatory soup does not alter brain and trigeminal microvascular passage. J Headache Pain 2015; 16:91. [PMID: 26512021 PMCID: PMC4627622 DOI: 10.1186/s10194-015-0575-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 10/21/2015] [Indexed: 01/24/2023] Open
Abstract
Background Migraine is a paroxysmal, disabling primary headache that affects 16 % of the adult population. In spite of decades of intense research, the origin and the pathophysiology mechanisms involved are still not fully known. Although triptans and gepants provide effective relief from acute migraine for many patients, their site of action remains unidentified. It has been suggested that during migraine attacks the leakiness of the blood-brain barrier (BBB) is altered, increasing the passage of anti-migraine drugs. This study aimed to investigate the effect of experimental inflammation, following dural application of complete Freund’s adjuvant (CFA) or inflammatory soup (IS) on brain and trigeminal microvascular passage. Methods In order to address this issue, we induced local inflammation in male Sprague-Dawley-rats dura mater by the addition of CFA or IS directly on the dural surface. Following 2, 24 or 48 h of inflammation we calculated permeability-surface area product (PS) for [51Cr]-EDTA in the trigeminal ganglion (TG), spinal trigeminal nucleus, cortex, periaqueductal grey and cerebellum. Results We observed that [51Cr]-EDTA did not pass into the central nervous system (CNS) in a major way. However, [51Cr]-EDTA readily passed the TG by >30 times compared to the CNS. Application of CFA or IS did not show altered transfer constants. Conclusions With these experiments we show that dural IS/CFA triggered TG inflammation, did not increase the BBB passage, and that the TG is readily exposed to circulating molecules. The TG could provide a site of anti-migraine drug interaction with effect on the trigeminal system. Electronic supplementary material The online version of this article (doi:10.1186/s10194-015-0575-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Cornelia Lundblad
- Department of Medicine, Institute of Clinical Sciences, University Hospital, Lund University, 22185, Lund, Sweden
| | - Kristian A Haanes
- Department of Clinical Experimental Research, Copenhagen University Hospital, Glostrup, Denmark
| | - Gustaf Grände
- Department of Medicine, Institute of Clinical Sciences, University Hospital, Lund University, 22185, Lund, Sweden
| | - Lars Edvinsson
- Department of Medicine, Institute of Clinical Sciences, University Hospital, Lund University, 22185, Lund, Sweden. .,Department of Clinical Experimental Research, Copenhagen University Hospital, Glostrup, Denmark.
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Lukács M, Haanes KA, Majláth Z, Tajti J, Vécsei L, Warfvinge K, Edvinsson L. Dural administration of inflammatory soup or Complete Freund's Adjuvant induces activation and inflammatory response in the rat trigeminal ganglion. J Headache Pain 2015; 16:564. [PMID: 26329487 PMCID: PMC4556720 DOI: 10.1186/s10194-015-0564-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 08/19/2015] [Indexed: 03/31/2024] Open
Abstract
Background Migraine is a painful disorder with a huge impact on individual and public health. We hypothesize that migraine pain originates from a central mechanism that results secondarily in hypersensitivity in peripheral afferents associated with the cerebral and cranial blood vessels. It has previously been shown that application of inflammatory or algesic substances onto the dura mater or chemical stimulation of the dural receptive fields causes hypersensitivity to mechanical and thermal stimulation together with direct activation of the TG. We asked whether local inflammation of dura mater induces inflammatory activation in the trigeminal ganglion. Methods We performed topical administration of inflammatory soup (IS) or Complete Freund’s Adjuvant (CFA) onto an exposed area of the rat dura mater in vivo for 20 min. The window was closed and the rats were sacrificed after 4 h and up to 7 days. Myography was performed on middle meningeal arteries. The trigeminal ganglia were removed and processed for immunohistochemistry or Western blot. Results Both CFA and IS induced enhanced expression of pERK1/2, IL-1β and CGRP in the trigeminal ganglia. The pERK1/2 immunoreactivity was mainly seen in the satellite glial cells, while IL-1β reactivity was observed in the neuronal cytoplasm, close to the cell membrane, seemingly as sign of neuro-glial interaction. The CGRP expression in the neurons and nerve fibres was enhanced after the application of either inflammatory agent. Myography resulted in a strong vasoconstrictor response to IS, but not to CFA. Conclusions These results suggest that the application of IS or CFA onto the dura mater causes long-term activation of the TG and demonstrate the importance of the neuro-glial interaction in the activation of the trigeminovascular system. Electronic supplementary material The online version of this article (doi:10.1186/s10194-015-0564-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- M Lukács
- Department of Medicine, Institute of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Sölvegatan 17, SE 221 84, Lund, Sweden
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Edvinsson J, Warfvinge K, Edvinsson L. Modulation of inflammatory mediators in the trigeminal ganglion by botulinum neurotoxin type A: an organ culture study. J Headache Pain 2015; 16:555. [PMID: 26245187 PMCID: PMC4526514 DOI: 10.1186/s10194-015-0555-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 07/11/2015] [Indexed: 12/25/2022] Open
Abstract
Background Onabotulinumtoxin type A (BoNT-A) has been found to reduce pain in chronic migraine. The aim of the present study was to ask if BoNT-A can interact directly on sensory mechanisms in the trigeminal ganglion (TG) using an organ culture method. Methods To induce inflammation, rat TGs were incubated for 24 hrs with either the mitogen MEK1/2 inhibitor U0126, BoNT-A or NaCl. After this the TGs were prepared for immunohistochemistry. Sections of the TG were then incubated with primary antibodies against CGRP (neuronal transmitter), iNOS (inflammatory marker), IL-1β (Interleukin 1β), SNAP-25 (synaptic vesicle docking protein) or SV2-A (Botulinum toxin receptor element). Results We report that CGRP, iNOS, IL-1β, SNAP-25 and SV2-A were observed in fresh TG with a differential distribution. Interestingly, NaCl organ culture of the TG resulted in enhanced expression of CGRP and SNAP-25 in neurons and iNOS in SGCs. Co-incubation with U0126 or BoNT-A retained the increased expression of SNAP-25, while it decreased the IL-1β immunoreactivity in neurons. The iNOS expression in SGCs returned to levels observed in fresh specimens. Moreover, we observed no alteration SV2-A expression in SGCs. Thus, the overall picture is that both U0126 and BoNT-A have the ability to modify the expression of certain molecules in the TG. Conclusion We hypothesize that chronic migraine might be associated with some degree of inflammation in the TG that could involve both neurons and SGCs. It is clinically well recognized that treatment with corticosteroids will reduce the symptoms of chronic migraine; however this remedy is associated with long-term side effects. Understanding the mechanisms involved in the expressional alterations may suggest novel ways to modify the changes and indicate novel therapeutics. The results of the present work illustrate one way by which BoNT-A may modify these expressional alterations.
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Walker CS, Sundrum T, Hay DL. PACAP receptor pharmacology and agonist bias: analysis in primary neurons and glia from the trigeminal ganglia and transfected cells. Br J Pharmacol 2014; 171:1521-33. [PMID: 24303997 DOI: 10.1111/bph.12541] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 11/25/2013] [Accepted: 11/29/2013] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND AND PURPOSE A major challenge in the development of new medicines targeting GPCRs is the ability to quantify drug action in physiologically relevant models. Primary cell models that closely resemble the clinically relevant in vivo site of drug action are important translational tools in drug development. However, pharmacological studies in these models are generally very limited due to the methodology used. EXPERIMENTAL APPROACH We used a neuropeptide system to demonstrate the applicability of using highly sensitive signalling assays in primary cells. We quantified the action of pituitary adenylate cyclase-activating peptide (PACAP)-38, PACAP-27 and vasoactive intestinal polypeptide in primary cultures of neurons and glia derived from rat trigeminal ganglia (TG), comparing our observations to transfected cells. KEY RESULTS PACAP-responsive receptors in rat trigeminal neurons, glia and transfected PAC1n receptors were pharmacologically distinct. PACAP-38, but not PACAP-27, activated ERK in glia, while both forms stimulated cellular cAMP production. PACAP(6-38) also displayed cell-type-dependent, agonist-specific, antagonism. CONCLUSIONS AND IMPLICATIONS The complexity of PACAP pharmacology in the TG may help to direct, more effectively, the development of disease treatments targeting the PACAP receptor. We suggest that these methodologies are broadly applicable to other primary cell types of human or animal origin, and that our approach may allow more thorough characterization of ligand properties in physiologically relevant cell types.
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Affiliation(s)
- C S Walker
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Centre for Brain Research, University of Auckland, Auckland, New Zealand
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Huang D, Li S, Dhaka A, Story GM, Cao YQ. Expression of the transient receptor potential channels TRPV1, TRPA1 and TRPM8 in mouse trigeminal primary afferent neurons innervating the dura. Mol Pain 2012; 8:66. [PMID: 22971321 PMCID: PMC3489865 DOI: 10.1186/1744-8069-8-66] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Accepted: 08/18/2012] [Indexed: 11/13/2022] Open
Abstract
Background Migraine and other headache disorders affect a large percentage of the population and cause debilitating pain. Activation and sensitization of the trigeminal primary afferent neurons innervating the dura and cerebral vessels is a crucial step in the “headache circuit”. Many dural afferent neurons respond to algesic and inflammatory agents. Given the clear role of the transient receptor potential (TRP) family of channels in both sensing chemical stimulants and mediating inflammatory pain, we investigated the expression of TRP channels in dural afferent neurons. Methods We used two fluorescent tracers to retrogradely label dural afferent neurons in adult mice and quantified the abundance of peptidergic and non-peptidergic neuron populations using calcitonin gene-related peptide immunoreactivity (CGRP-ir) and isolectin B4 (IB4) binding as markers, respectively. Using immunohistochemistry, we compared the expression of TRPV1 and TRPA1 channels in dural afferent neurons with the expression in total trigeminal ganglion (TG) neurons. To examine the distribution of TRPM8 channels, we labeled dural afferent neurons in mice expressing farnesylated enhanced green fluorescent protein (EGFPf) from a TRPM8 locus. We used nearest-neighbor measurement to predict the spatial association between dural afferent neurons and neurons expressing TRPA1 or TRPM8 channels in the TG. Results and conclusions We report that the size of dural afferent neurons is significantly larger than that of total TG neurons and facial skin afferents. Approximately 40% of dural afferent neurons exhibit IB4 binding. Surprisingly, the percentage of dural afferent neurons containing CGRP-ir is significantly lower than those of total TG neurons and facial skin afferents. Both TRPV1 and TRPA1 channels are expressed in dural afferent neurons. Furthermore, nearest-neighbor measurement indicates that TRPA1-expressing neurons are clustered around a subset of dural afferent neurons. Interestingly, TRPM8-expressing neurons are virtually absent in the dural afferent population, nor do these neurons cluster around dural afferent neurons. Taken together, our results suggest that TRPV1 and TRPA1 but not TRPM8 channels likely contribute to the excitation of dural afferent neurons and the subsequent activation of the headache circuit. These results provide an anatomical basis for understanding further the functional significance of TRP channels in headache pathophysiology.
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Affiliation(s)
- Dongyue Huang
- Washington University Pain Center and Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Pituitary adenylate cyclase-activating polypeptide plays a key role in nitroglycerol-induced trigeminovascular activation in mice. Neurobiol Dis 2012; 45:633-44. [DOI: 10.1016/j.nbd.2011.10.010] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 09/30/2011] [Accepted: 10/10/2011] [Indexed: 11/16/2022] Open
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Neeb L, Hellen P, Boehnke C, Hoffmann J, Schuh-Hofer S, Dirnagl U, Reuter U. IL-1β stimulates COX-2 dependent PGE₂ synthesis and CGRP release in rat trigeminal ganglia cells. PLoS One 2011; 6:e17360. [PMID: 21394197 PMCID: PMC3048859 DOI: 10.1371/journal.pone.0017360] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2010] [Accepted: 01/28/2011] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Pro-inflammatory cytokines like Interleukin-1 beta (IL-1β) have been implicated in the pathophysiology of migraine and inflammatory pain. The trigeminal ganglion and calcitonin gene-related peptide (CGRP) are crucial components in the pathophysiology of primary headaches. 5-HT1B/D receptor agonists, which reduce CGRP release, and cyclooxygenase (COX) inhibitors can abort trigeminally mediated pain. However, the cellular source of COX and the interplay between COX and CGRP within the trigeminal ganglion have not been clearly identified. METHODS AND RESULTS 1. We used primary cultured rat trigeminal ganglia cells to assess whether IL-1β can induce the expression of COX-2 and which cells express COX-2. Stimulation with IL-1β caused a dose and time dependent induction of COX-2 but not COX-1 mRNA. Immunohistochemistry revealed expression of COX-2 protein in neuronal and glial cells. 2. Functional significance was demonstrated by prostaglandin E2 (PGE(2)) release 4 hours after stimulation with IL-1β, which could be aborted by a selective COX-2 (parecoxib) and a non-selective COX-inhibitor (indomethacin). 3. Induction of CGRP release, indicating functional neuronal activation, was seen 1 hour after PGE(2) and 24 hours after IL-1β stimulation. Immunohistochemistry showed trigeminal neurons as the source of CGRP. IL-1β induced CGRP release was blocked by parecoxib and indomethacin, but the 5-HT1B/D receptor agonist sumatriptan had no effect. CONCLUSION We identified a COX-2 dependent pathway of cytokine induced CGRP release in trigeminal ganglia neurons that is not affected by 5-HT1B/D receptor activation. Activation of neuronal and glial cells in the trigeminal ganglion by IL-β leads to an elevated expression of COX-2 in these cells. Newly synthesized PGE(2) (by COX-2) in turn activates trigeminal neurons to release CGRP. These findings support a glia-neuron interaction in the trigeminal ganglion and demonstrate a sequential link between COX-2 and CGRP. The results could help to explain the mechanism of action of COX-2 inhibitors in migraine.
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Affiliation(s)
- Lars Neeb
- Department of Neurology and Experimental Neurology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Peter Hellen
- Department of Neurology and Experimental Neurology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Carsten Boehnke
- Department of Neurology and Experimental Neurology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Jan Hoffmann
- Department of Neurology and Experimental Neurology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Sigrid Schuh-Hofer
- Department of Neurology, Universitätsklinikum Tübingen, Tübingen, Germany
| | - Ulrich Dirnagl
- Department of Neurology and Experimental Neurology, Charité Universitätsmedizin Berlin, Berlin, Germany
| | - Uwe Reuter
- Department of Neurology and Experimental Neurology, Charité Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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Amrutkar DV, Ploug KB, Olesen J, Jansen-Olesen I. Role for voltage gated calcium channels in calcitonin gene-related peptide release in the rat trigeminovascular system. Neuroscience 2010; 172:510-7. [PMID: 20955764 DOI: 10.1016/j.neuroscience.2010.10.032] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 10/08/2010] [Accepted: 10/11/2010] [Indexed: 11/16/2022]
Abstract
Clinical and genetic studies have suggested a role for voltage gated calcium channels (VGCCs) in the pathogenesis of migraine. Release of calcitonin gene-related peptide (CGRP) from trigeminal neurons has also been implicated in migraine. The VGCCs are located presynaptically on neurons and are involved in the release of these peptides to different stimuli. We have examined the presence and importance of VGCCs in controlling the CGRP release from rat dura mater, freshly isolated trigeminal ganglion (TG) and trigeminal nucleus caudalis (TNC). Each of the four VGCCs, P/Q-, N-, and L- and T-type are abundantly found in TG and TNC relative to the dura mater and each mediates a significant fraction of high potassium concentration induced CGRP release. In dura mater, blockade of P/Q-, N- and L-type VGCCs by ω-agatoxin TK, ω-conotoxin GVIA and nimodipine at 1 μM respectively, significantly decreased the potassium induced CGRP release. In the absence of calcium ions (Ca2+) and in the presence of a cocktail of blockers, the stimulated CGRP release from dura mater was reduced almost to the same level as basal CGRP release. In the TG ω-conotoxin GVIA inhibited the potassium induced CGRP release significantly. In the absence of Ca2+ and in the presence of a cocktail of blockers the stimulated CGRP release was significantly reduced. In the TNC only the cocktail of blockers and the absence of Ca2+ could reduce the potassium induced release significantly. These results suggest that depolarization by high potassium releases CGRP, and the release is regulated by Ca2+ ions and voltage-gated calcium channels.
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Affiliation(s)
- D V Amrutkar
- Department of Neurology and Danish Headache Center, Glostrup Research Institute, Glostrup Hospital, Faculty of Health Sciences, University of Copenhagen, Nordre Ringvej 69, 2600 Glostrup, Denmark
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Tajti J, Kuris A, Vécsei L, Xu CB, Edvinsson L. Organ culture of the trigeminal ganglion induces enhanced expression of calcitonin gene-related peptide via activation of extracellular signal-regulated protein kinase 1/2. Cephalalgia 2010; 31:95-105. [PMID: 20851839 DOI: 10.1177/0333102410382796] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND AND OBJECTIVE Clinical and experimental studies have revealed a central role of calcitonin gene-related peptide (CGRP) in primary headaches. The role of extracellular signal-regulated kinase 1 and 2 (ERK1/2) in neuronal and glial cell expression of CGRP- immunoreactivity (-ir) in rat trigeminal ganglia was studied with an organ culture method. EXPERIMENTAL PROCEDURES Sections of adult rat trigeminal ganglia were cultured for up to 48 hours, examined with immunohistochemistry and quantitative real-time polymerase chain reaction (PCR) assay. Specific antibodies against CGRP, phosphorylated ERK1/2 (pERK1/2), total ERK1/2 (tERK1/2), phosphorylated p38 (pp38), phosphorylated C-Jun-N-terminal protein kinase (pJNK), pro-calcitonin (pro-CT), CGRP receptor activity modifying protein 1 (RAMP1), glutamine synthetase (GS) and pro-CT were used. To explore molecular mechanisms involved in the organ culture-induced CGRP-ir in neurons and glial cells, the effects of the MEK/ERK1/2 inhibitor U0126, its inactive analogue U0124, the p38 inhibitor SB203580 and the JNK inhibitor SP600125 were studied. RESULTS In fresh ganglia, small- and medium-sized neurons were CGRP-ir while some larger neurons displayed RAMP1-ir. Glial cells were negative to both. After organ culture, neurons showed enhanced CGRP- and RAMP1-ir. In addition, some glial cells were RAMP1- and CGRP-ir. Isolated glial cells and neurons were found to contain CGRP mRNA, and showed pro-CT-ir, suggestive of local formation of CGRP. Neurons and glial cells showed enhanced pERK1/2-ir already after two hours of organ culture and this remained elevated for 48 hours. There was transient pJNK-ir in neurons at two hours, while pp38-ir was not altered. U0126 reduced the enhanced pERK1/2-ir, while U0124 had no such effect; the CGRP-ir in neurons and glial cells was reduced at 48 hours and in parallel the CGRP mRNA expression was lower at 24 hours. CONCLUSION We suggest that in conditions of elevated CGRP expression, inhibition of ERK1/2 might be an option for novel treatment.
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Affiliation(s)
- János Tajti
- Department of Medicine, Institute of Clinical Science, University Hospital, Lund University, Lund, Sweden
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Proteomic analysis uncovers novel actions of the neurosecretory protein VGF in nociceptive processing. J Neurosci 2009; 29:13377-88. [PMID: 19846725 DOI: 10.1523/jneurosci.1127-09.2009] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Peripheral tissue injury is associated with changes in protein expression in sensory neurons that may contribute to abnormal nociceptive processing. We used cultured dorsal root ganglion (DRG) neurons as a model of axotomized neurons to investigate early changes in protein expression after nerve injury. Comparing protein levels immediately after DRG dissociation and 24 h later by proteomic differential expression analysis, we found a substantial increase in the levels of the neurotrophin-inducible protein VGF (nonacronymic), a putative neuropeptide precursor. In a rodent model of nerve injury, VGF levels were increased within 24 h in both injured and uninjured DRG neurons, and the increase persisted for at least 7 d. VGF was also upregulated 24 h after hindpaw inflammation. To determine whether peptides derived from proteolytic processing of VGF participate in nociceptive signaling, we examined the spinal effects of AQEE-30 and LQEQ-19, potential proteolytic products shown previously to be bioactive. Each peptide evoked dose-dependent thermal hyperalgesia that required activation of the mitogen-activated protein kinase p38. In addition, LQEQ-19 induced p38 phosphorylation in spinal microglia when injected intrathecally and in the BV-2 microglial cell line when applied in vitro. In summary, our results demonstrate rapid upregulation of VGF in sensory neurons after nerve injury and inflammation and activation of microglial p38 by VGF peptides. Therefore, VGF peptides released from sensory neurons may participate in activation of spinal microglia after peripheral tissue injury.
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