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Lambert GA, Zagami AS. Effects of somatostatin, a somatostatin agonist, and an antagonist, on a putative migraine trigger pathway. Neuropeptides 2024; 103:102399. [PMID: 38118293 DOI: 10.1016/j.npep.2023.102399] [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: 07/16/2023] [Revised: 11/15/2023] [Accepted: 12/04/2023] [Indexed: 12/22/2023]
Abstract
OBJECTIVE To determine whether somatostatin (SST) could be a cortico-brainstem neurotransmitter involved in producing the headache of migraine. BACKGROUND There is evidence to support the idea that a cortico-brainstem-trigeminal nucleus neuraxis might be responsible for producing migraine headache; we have suggested that SST may be one of the neurotransmitters involved. METHODS Rats were anesthetised and prepared for recording neurons in either the periaqueductal gray matter (PAG) or nucleus raphe magnus (NRM), as well as the trigeminal nucleus caudalis (TNC). The dura mater and facial skin were stimulated electrically or mechanically. SST, the SST agonist L054264 and the SST antagonist CYN54806 were injected intravenously, by microinjection, or by iontophoresis into the PAG or NRM. Cortical neuronal activity was provoked by cortical spreading depression (CSD) or light flash (LF) and was monitored by recording cortical blood flow (CBF). RESULTS Intravenous injection of SST: (a) selectively decreased the responses of TNC neurons to stimulation of the dura, but not skin, for up to 5 h; (b) decreased the ongoing discharge rate of TNC neurons while simultaneously increasing the discharge rate of neurons in either brainstem nucleus and; (c) prevented, or reversed, the effect of CSD and LF on brainstem and trigeminal neuron discharge rates. CSD and LF decreased the discharge rate of neurons in both brainstem nuclei and increased the discharge rate of TNC neurons. These effects were reversed by L054264 and mimicked by CYN54806. Injections of L054264 into the PAG or NRM reduced the response of TNC neurons to dural stimulation and skin stimulation differentially, depending on the nucleus injected. Injections of CYN54806 into either brainstem nucleus potentiated the responses of TNC neurons to dural and skin stimulation, but without a marked differential effect. CONCLUSIONS These results imply that SST could be a neurotransmitter in a pathway responsible for migraine pain.
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Affiliation(s)
- Geoffrey A Lambert
- School of Clinical Medicine, Faculty of Medicine, University of New South Wales, Australia.
| | - Alessandro S Zagami
- School of Clinical Medicine, Faculty of Medicine, University of New South Wales, Australia; Institute of Neurological Sciences, Prince of Wales Hospital, Randwick, NSW 2031, Australia
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Vestibular migraine: the chameleon in vestibular disease. Neurol Sci 2021; 42:1719-1731. [PMID: 33666767 DOI: 10.1007/s10072-021-05133-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Accepted: 02/20/2021] [Indexed: 12/19/2022]
Abstract
Vestibular migraine (VM) has been recently receiving increasing attention as an independent disease concept. It is a common cause of dizziness or headache; however, it was not clearly defined until 2018. Its diagnosis mainly relies on clinical history, including vertigo and migraine, as indicated by the appendix of the 3rd edition of the International Classification Diagnostic Criteria for Headache Diseases. There is often an overlap of vertigo and migraine across vestibular diseases; therefore, VM often imitates various vestibular diseases. Additionally, VM lacks specific laboratory biomarkers; therefore, it has high misdiagnosis and missed diagnosis rates. Therefore, numerous clinical patients could have inaccurate diagnoses and improper treatment. Therefore, there is a need for further basic research to further clarify the pathogenesis. Moreover, there is a need for clinical trials focusing on specific laboratory biomarkers, including serological, radiological, and electrophysiological examinations, to develop more detailed and complete diagnostic criteria.
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Zagami AS, Shaikh S, Mahns D, Lambert GA. A potential role for two brainstem nuclei in craniovascular nociception and the triggering of migraine headache. Cephalalgia 2020; 41:203-216. [PMID: 32990035 DOI: 10.1177/0333102420960039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AIM To use an animal model of migraine to test whether migraine headache might arise from a brainstem-trigeminal nucleus pathway. METHODS We measured evoked and spontaneous activity of second-order trigeminovascular neurons in rats to test whether the activity of these neurons increased following the induction of cortical spreading depression or the imposition of light flash - two potential migraine triggers, or headache provokers. We then tested whether drugs that could activate, or inactivate, neurons of the nucleus raphe magnus or the periaqueductal gray matter, would affect any such increases selectively for the dura mater. RESULTS Injection of sodium glutamate (a neuronal excitant) into these two nuclei selectively inhibited the responses of trigeminovascular second-order neurons to dura mater, but not to facial skin, stimulation. Injection of lignocaine (a local anaesthetic) into these nuclei selectively potentiated the responses of these neurons to dura, but not to facial skin, stimulation. Furthermore, injections into either nucleus of glutamate inhibited the increase in the ongoing discharge rate of these neurons produced by cortical spreading depression and light flash. CONCLUSIONS These results provide indirect evidence that trigeminovascular nociception may be tightly controlled by these two nuclei, whereas cutaneous trigeminal sensation may be less so. These nuclei may be relays of one possible brainstem-trigeminal pathway that could mediate migraine headache. Modification of neuronal activity in these two nuclei produced by migraine (headache) triggers may lie behind the pain of a migraine attack, at least in some cases.
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Affiliation(s)
- Alessandro S Zagami
- Prince of Wales Clinical School, UNSW (Sydney), NSW, Australia.,Institute of Neurological Sciences, Prince of Wales Hospital, Randwick, NSW, Australia
| | - Sumaiya Shaikh
- School of Medicine, Western Sydney University, Penrith, NSW, Australia
| | - David Mahns
- School of Medicine, Western Sydney University, Penrith, NSW, Australia
| | - Geoffrey A Lambert
- Prince of Wales Clinical School, UNSW (Sydney), NSW, Australia.,School of Medicine, Western Sydney University, Penrith, NSW, Australia
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Winters BL, Jeong HJ, Vaughan CW. Inflammation induces developmentally regulated sumatriptan inhibition of spinal synaptic transmission. Br J Pharmacol 2020; 177:3730-3743. [PMID: 32352556 DOI: 10.1111/bph.15089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND AND PURPOSE While triptans are used to treat migraine, there is evidence that they also reduce inflammation-induced pain at the spinal level. The cellular mechanisms underlying this spinal enhancement are unknown. We examined whether inflammation alters sumatriptan modulation of synaptic transmission in the rat spinal dorsal horn. EXPERIMENTAL APPROACH Three to four days following intraplantar injection of complete Freund's adjuvant (CFA) or saline, whole cell recordings of evoked glutamatergic EPSCs were made from lumbar lamina I-II dorsal horn neurons in rat spinal slices KEY RESULTS: In 2- to 3-week-old animals, sumatriptan reduced the amplitude of evoked EPSCs and this was greater in slices from CFA, compared to saline-injected rats. In CFA-injected animals, sumatriptan increased the paired pulse ratio of evoked EPSCs and reduced the rate of spontaneous miniature EPSCs. The 5-HT1B and 5-HT1D agonists CP9 3129 and PNU109291 both inhibited evoked EPSCs in CFA but not saline-injected rats. By contrast, the 5-HT1A agonist R(+)-8-OH-DPAT inhibited evoked EPSCs in saline but not CFA-injected rats. In CFA-injected rats, the sumatriptan-induced inhibition of evoked EPSCs was reduced by the 5-HT1B and 5-HT1D antagonists NAS181 and BRL-15572. Intriguingly, the difference in sumatriptan inhibition between CFA and saline-injected animals was only observed in animals less than 4 weeks old. CONCLUSION AND IMPLICATIONS These findings indicate that inflammation induces a developmentally regulated 5-HT1B/1D presynaptic inhibition of excitatory transmission into the rat superficial dorsal horn. Thus, triptans could potentially act as spinal analgesic agents for inflammatory pain in the juvenile setting.
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Affiliation(s)
- Bryony L Winters
- Pain Management Research Institute and Kolling Institute of Medical Research, The University of Sydney at Royal North Shore Hospital, St. Leonards, New South Wales, Australia
| | - Hyo-Jin Jeong
- Pain Management Research Institute and Kolling Institute of Medical Research, The University of Sydney at Royal North Shore Hospital, St. Leonards, New South Wales, Australia
| | - Christopher W Vaughan
- Pain Management Research Institute and Kolling Institute of Medical Research, The University of Sydney at Royal North Shore Hospital, St. Leonards, New South Wales, Australia
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Harriott AM, Strother LC, Vila-Pueyo M, Holland PR. Animal models of migraine and experimental techniques used to examine trigeminal sensory processing. J Headache Pain 2019; 20:91. [PMID: 31464579 PMCID: PMC6734323 DOI: 10.1186/s10194-019-1043-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/19/2019] [Indexed: 12/12/2022] Open
Abstract
Background Migraine is a common debilitating condition whose main attributes are severe recurrent headaches with accompanying sensitivity to light and sound, nausea and vomiting. Migraine-related pain is a major cause of its accompanying disability and can encumber almost every aspect of daily life. Main body Advancements in our understanding of the neurobiology of migraine headache have come in large from basic science research utilizing small animal models of migraine-related pain. In this current review, we aim to describe several commonly utilized preclinical models of migraine. We will discuss the diverse array of methodologies for triggering and measuring migraine-related pain phenotypes and highlight briefly specific advantages and limitations therein. Finally, we will address potential future challenges/opportunities to refine existing and develop novel preclinical models of migraine that move beyond migraine-related pain and expand into alternate migraine-related phenotypes. Conclusion Several well validated animal models of pain relevant for headache exist, the researcher should consider the advantages and limitations of each model before selecting the most appropriate to answer the specific research question. Further, we should continually strive to refine existing and generate new animal and non-animal models that have the ability to advance our understanding of head pain as well as non-pain symptoms of primary headache disorders.
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Affiliation(s)
- Andrea M Harriott
- Neurovascular Research Lab, Department of Radiology, Massachusetts General Hospital, Charlestown, MA, USA.,Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
| | - Lauren C Strother
- Headache Group, Department of Basic and Clinical Neuroscience, Institute of Psychology, Psychiatry and Neuroscience, King's College London, James Black Centre, 125 Coldharbour Lane, London, SE5 9NU, UK
| | - Marta Vila-Pueyo
- Headache Group, Department of Basic and Clinical Neuroscience, Institute of Psychology, Psychiatry and Neuroscience, King's College London, James Black Centre, 125 Coldharbour Lane, London, SE5 9NU, UK
| | - Philip R Holland
- Headache Group, Department of Basic and Clinical Neuroscience, Institute of Psychology, Psychiatry and Neuroscience, King's College London, James Black Centre, 125 Coldharbour Lane, London, SE5 9NU, UK.
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Price TJ, Gold MS. From Mechanism to Cure: Renewing the Goal to Eliminate the Disease of Pain. PAIN MEDICINE 2019; 19:1525-1549. [PMID: 29077871 DOI: 10.1093/pm/pnx108] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Objective Persistent pain causes untold misery worldwide and is a leading cause of disability. Despite its astonishing prevalence, pain is undertreated, at least in part because existing therapeutics are ineffective or cause intolerable side effects. In this review, we cover new findings about the neurobiology of pain and argue that all but the most transient forms of pain needed to avoid tissue damage should be approached as a disease where a cure can be the goal of all treatment plans, even if attaining this goal is not yet always possible. Design We reviewed the literature to highlight recent advances in the area of the neurobiology of pain. Results We discuss barriers that are currently hindering the achievement of this goal, as well as the development of new therapeutic strategies. We also discuss innovations in the field that are creating new opportunities to treat and even reverse persistent pain, some of which are in late-phase clinical trials. Conclusion We conclude that the confluence of new basic science discoveries and development of new technologies are creating a path toward pain therapeutics that should offer significant hope of a cure for patients and practitioners alike. Classification of Evidence. Our review points to new areas of inquiry for the pain field to advance the goal of developing new therapeutics to treat chronic pain.
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Affiliation(s)
- Theodore J Price
- School of Behavioral and Brain Sciences, The University of Texas at Dallas, Dallas, Texas
| | - Michael S Gold
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Kilinc E, Guerrero-Toro C, Zakharov A, Vitale C, Gubert-Olive M, Koroleva K, Timonina A, Luz LL, Shelukhina I, Giniatullina R, Tore F, Safronov BV, Giniatullin R. Serotonergic mechanisms of trigeminal meningeal nociception: Implications for migraine pain. Neuropharmacology 2016; 116:160-173. [PMID: 28025094 DOI: 10.1016/j.neuropharm.2016.12.024] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 12/02/2016] [Accepted: 12/22/2016] [Indexed: 10/20/2022]
Abstract
Serotonergic mechanisms play a central role in migraine pathology. However, the region-specific effects of serotonin (5-HT) mediated via multiple types of receptors in the nociceptive system are poorly understood. Using extracellular and patch-clamp recordings, we studied the action of 5-HT on the excitability of peripheral and central terminals of trigeminal afferents. 5-HT evoked long-lasting TTX-sensitive firing in the peripheral terminals of meningeal afferents, the origin site of migraine pain. Cluster analysis revealed that in majority of nociceptive fibers 5-HT induced either transient or persistent spiking activity with prevailing delta and theta rhythms. The 5-HT3-receptor antagonist MDL-72222 or 5-HT1B/D-receptor antagonist GR127935 largely reduced, but their combination completely prevented the excitatory pro-nociceptive action of 5-HT. The 5-HT3 agonist mCPBG activated spikes in MDL-72222-dependent manner but the 5HT-1 receptor agonist sumatriptan did not affect the nociceptive firing. 5-HT also triggered peripheral CGRP release in meninges, which was blocked by MDL-72222.5-HT evoked fast membrane currents and Ca2+ transients in a fraction of trigeminal neurons. Immunohistochemistry showed expression of 5-HT3A receptors in fibers innervating meninges. Endogenous release of 5-HT from degranulated mast cells increased nociceptive firing. Low pH but not histamine strongly activated firing. 5-HT reduced monosynaptic inputs from trigeminal Aδ- and C-afferents to the upper cervical lamina I neurons and this effect was blocked by MDL-72222. Consistent with central inhibitory effect, 5-HT reduced CGRP release in the brainstem slices. In conclusion, 5-HT evokes powerful pro-nociceptive peripheral and anti-nociceptive central effects in trigeminal system transmitting migraine pain.
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Affiliation(s)
- Erkan Kilinc
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland; Abant Izzet Baysal University, Medical Faculty, Department of Physiology, 14280, Bolu, Turkey.
| | - Cindy Guerrero-Toro
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland.
| | - Andrey Zakharov
- Laboratory of Neurobiology, Kazan Federal University, 420008, Kazan, Russia; Department of Physiology, Kazan State Medical University, 420012, Kazan, Russia.
| | - Carmela Vitale
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland.
| | - Max Gubert-Olive
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland.
| | - Ksenia Koroleva
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland; Laboratory of Neurobiology, Kazan Federal University, 420008, Kazan, Russia
| | - Arina Timonina
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland
| | - Liliana L Luz
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal.
| | - Irina Shelukhina
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland; Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, 117997, Moscow, Russia.
| | - Raisa Giniatullina
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland.
| | - Fatma Tore
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland; Biruni University, School of Medicine, 34010, Istanbul, Turkey.
| | - Boris V Safronov
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal; Neuronal Networks Group, Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, 4200-135, Porto, Portugal.
| | - Rashid Giniatullin
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70211, Kuopio, Finland; Laboratory of Neurobiology, Kazan Federal University, 420008, Kazan, Russia.
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Tajti J, Majláth Z, Szok D, Csáti A, Vécsei L. Drug safety in acute migraine treatment. Expert Opin Drug Saf 2015; 14:891-909. [DOI: 10.1517/14740338.2015.1026325] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Lambert GA, Hoskin KL, Michalicek J, Panahi SE, Truong L, Zagami AS. Stimulation of dural vessels excites the SI somatosensory cortex of the cat via a relay in the thalamus. Cephalalgia 2013; 34:243-57. [DOI: 10.1177/0333102413508239] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Aim We carried out experiments in cats to determine the thalamo-cortical projection sites of trigeminovascular sensory neurons. Methods 1) We stimulated the middle meningeal artery (MMA) with C-fibre intensity electrical shocks and made field potential recordings over the somatosensory cortical surface. 2) We then recorded neurons in the ventroposteromedial (VPM) nucleus of the thalamus in search of neurons which could be activated from the skin, MMA and superior sagittal sinus. 3) Finally, we attempted to antidromically activate the neurons found in stage 2 by stimulating the responsive cortical areas revealed in stage 1. Results VPM neurons received trigeminovascular input, input from the V1 facial skin and could also be activated by electrical stimulation of the somatosensory cortex. VPM neurons activated from the cortex responded with short and invariant latencies (6.7 ± 7.7 msec mean and SD). They could follow high rates of stimulation and sometimes showed collision with orthodromic action potentials. Conclusions We conclude that somatosensory (SI) cortical stimulation excites trigeminovascular VPM neurons antidromically. In consequence, these VPM neurons project to the somatosensory cortex. These findings may help to explain the ability of migraineurs with headache in the trigeminal distribution to localise their pain to a particular region in this distribution.
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Affiliation(s)
| | - Karen L Hoskin
- Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Australia
| | - Jan Michalicek
- Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Australia
| | - Seyed E Panahi
- Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Australia
| | - Linda Truong
- Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Australia
| | - Alessandro S Zagami
- Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Australia
- Institute of Neurological Sciences, Prince of Wales Hospital, Australia
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Jeong HJ, Mitchell VA, Vaughan CW. Role of 5-HT(1) receptor subtypes in the modulation of pain and synaptic transmission in rat spinal superficial dorsal horn. Br J Pharmacol 2012; 165:1956-1965. [PMID: 21950560 DOI: 10.1111/j.1476-5381.2011.01685.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND AND PURPOSE 5-HT receptor agonists have variable nociceptive effects within the spinal cord. While there is some evidence for 5-HT(1A) spinally-mediated analgesia, the role of other 5-HT(1) receptor subtypes remains unclear. In the present study, we examined the spinal actions of a range of 5-HT(1) agonists, including sumatriptan, on acute pain, plus their effect on afferent-evoked synaptic transmission onto superficial dorsal horn neurons. EXPERIMENTAL APPROACH For in vivo experiments, 5-HT agonists were injected via chronically implanted spinal catheters to examine their effects in acute mechanical and thermal pain assays using a paw pressure analgesymeter and a Hargreave's device. For in vitro experiments, whole-cell patch-clamp recordings of primary afferent-evoked glutamatergic EPSC were made from lamina II neurons in rat lumbar spinal slices. KEY RESULTS Intrathecal (i.t.) delivery of the 5-HT(1A) agonist R ± 8-OH-DPAT (30-300 nmol) produced a dose-dependent thermal, but not mechanical, analgesia. Sumatriptan and the 5-HT(1B), 5-HT(1D), 5-HT(1F) agonists CP93129, PNU109291 and LY344864 (100 nmol) had no effect on either acute pain assay. R ± 8-OH-DPAT (1 µM) and sumatriptan (3 µM) both reduced the amplitude of the evoked EPSC. In contrast, CP93129, PNU109291 and LY344864 (0.3-3 µM) had no effect on the evoked EPSC. The actions of both R ± 8-OH-DPAT and sumatriptan were abolished by the 5-HT(1A) antagonist WAY100635 (3 µM). CONCLUSIONS AND IMPLICATIONS These findings indicate that the 5-HT(1A) receptor subtype predominantly mediates the acute antinociceptive and cellular actions of 5-HT(1) ligands within the rat superficial dorsal horn.
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Affiliation(s)
- Hyo-Jin Jeong
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, University of Sydney at Royal North Shore Hospital, NSW, Australia
| | - Vanessa A Mitchell
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, University of Sydney at Royal North Shore Hospital, NSW, Australia
| | - Christopher W Vaughan
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, University of Sydney at Royal North Shore Hospital, NSW, Australia
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Abstract
AIM To test the hypothesis that the clinical efficacy of triptans reflects convergent modulation of ion channels also involved in inflammatory mediator (IM)-induced sensitization of dural afferents. METHODS Acutely dissociated retrogradely labeled rat dural afferents were studied with whole cell and perforated patch techniques in the absence and presence of sumatriptan and/or IM (prostaglandin E2, bradykinin, and histamine). RESULTS Sumatriptan dose-dependently suppressed voltage-gated Ca²⁺ currents. Acute (2 min) sumatriptan application increased dural afferent excitability and occluded further IM-induced sensitization. In contrast, pre-incubation (30 min) with sumatriptan had no influence on dural afferent excitability and partially prevented IM-induced sensitization of dural afferents. The sumatriptan-induced suppression of voltage-gated Ca²⁺ currents and acute sensitization and pre-incubation-induced block of IM-induced sensitization were blocked by the 5-HT(1D) antagonist BRL 15572. Pre-incubation with sumatriptan failed to suppress the IM-induced decrease in action potential threshold and overshoot (which results from modulation of voltage-gated Na⁺ currents) and activation of Cl⁻ current, and had no influence on the Cl⁻ reversal potential. However, pre-incubation with sumatriptan caused a dramatic hyperpolarizing shift in the voltage dependence of K⁺ current activation. DISCUSSION These results indicate that although the actions of sumatriptan on dural afferents are complex, at least two distinct mechanisms underlie the antinociceptive actions of this compound. One of these mechanisms, the shift in the voltage dependence of K⁺ channel activation, may suggest a novel strategy for future development of anti-migraine agents.
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Affiliation(s)
- Andrea M. Harriott
- Department of Neural and Pain Sciences, Dental School, University of Maryland, Baltimore, MD 21201
- University of Maryland, Baltimore Medical Scientist Training Program, Baltimore, MD 21201
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213
| | - Nicole N. Scheff
- Center for Neuroscience at the University of Pittsburgh, Pittsburgh, PA 15213
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA 15213
| | - Michael S. Gold
- Department of Anesthesiology, University of Pittsburgh, Pittsburgh, PA 15213
- Department of Neurobiology and Medicine, Division of Gastroenterology, Hepatology and Nutrition, University of Pittsburgh, Pittsburgh, PA 15213
- Center for Neuroscience at the University of Pittsburgh, Pittsburgh, PA 15213
- Pittsburgh Center for Pain Research, University of Pittsburgh, Pittsburgh, PA 15213
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Lambert GA, Truong L, Zagami AS. Effect of cortical spreading depression on basal and evoked traffic in the trigeminovascular sensory system. Cephalalgia 2011; 31:1439-51. [PMID: 21940490 DOI: 10.1177/0333102411422383] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
AIM To use an animal model to test whether migraine pain arises peripherally or centrally. METHODS We monitored the spontaneous and evoked activity of second-order trigeminovascular neurons in rats to test whether traffic increased following a potential migraine trigger (cortical spreading depression, CSD) and by what mechanism any such change was mediated. RESULTS Neurons (n = 33) responded to stimulation of the dura mater and facial skin with A-δ latencies. They were spontaneously active with a discharge rate of 6.1 ± 6.4 discharges s(-1). Injection of 10 µg lignocaine into the trigeminal ganglion produced a fully reversible reduction of the spontaneous discharge rate of neurons. Neuronal discharge rate returned to normal by 90 min. Lignocaine reduced the evoked responses of neurons to dural stimulation to 37% and to facial skin stimulation to 53% of control. Induction of CSD by cortical injection of KCl increased the spontaneous discharge rate of neurons from 2.9 to 16.3 discharges s(-1) at 20 min post CSD. Injection of 10 µg lignocaine into the trigeminal ganglion at this time failed to arrest or reverse this increase. Injection of lignocaine prior to the initiation of CSD failed to prevent the subsequent development of CSD-induced increases in discharge rates. CONCLUSIONS These results suggest that there is a continuous baseline traffic in primary trigeminovascular fibres and that CSD does not act to increase this traffic by a peripheral action alone - rather, it must produce some of its effect by a mechanism intrinsic to the central nervous system. Thus the pain of migraine may not always be the result of peripheral sensory stimulation, but may also arise by a central mechanism.
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Charbit AR, Akerman S, Goadsby PJ. Trigeminocervical complex responses after lesioning dopaminergic A11 nucleus are modified by dopamine and serotonin mechanisms. Pain 2011; 152:2365-2376. [PMID: 21868165 DOI: 10.1016/j.pain.2011.07.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 07/05/2011] [Accepted: 07/06/2011] [Indexed: 11/26/2022]
Abstract
Both serotonergic and dopaminergic receptor modulation can alter trigeminal nociceptive processing, and descending A11 dopaminergic projections can affect trigeminal nociceptive transmission. Here we aimed to test the interaction between dopamine D(2) and serotonin 5-HT(1B/1D) receptors and their individual and combined effects in order to better understand the relationship of the descending influences of these systems on nociceptive trigeminovascular afferents. Extracellular recordings were made in the rat trigeminocervical complex in response to electrical stimulation of the dura mater and mechanical noxious and innocuous stimulation of the ipsilateral ophthalmic dermatome. The A11 nucleus was lesioned, and following the resultant facilitation of neuronal firing, one of a selective 5-HT(1B/1D) receptor agonist (naratriptan), selective 5-HT(1B/1D) receptor antagonist (GR127935), a selective D(2)-like receptor agonist (quinpirole), and a selective D(1)-like receptor agonist (dihydrexidine), or a combination of the above, were administered. Both quinpirole and quinpirole with naratriptan inhibited firing in the trigeminocervical complex evoked by noxious stimuli, reducing it below prelesion baseline, while the response to innocuous stimuli was reduced back to baseline. Both naratriptan alone, and quinpirole combined with GR127935, inhibited firing in the trigeminocervical complex evoked by noxious stimuli, returning it to prelesion baseline, while the response to innocuous stimuli remained facilitated. Immunohistochemical staining demonstrated D(2)-receptor and 5-HT(1B/1D)-receptor colocalization in the trigeminocervical complex. The data suggest that the serotonergic and dopaminergic antinociceptive pathways act simultaneously on neurons in the trigeminocervical complex, and both amine systems need to be functioning for trigeminal sensitization to be reversed.
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Affiliation(s)
- Annabelle R Charbit
- Headache Group - Department of Neurology, University of California San Francisco, San Francisco, CA 94115, USA
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Abstract
This article reviews the baffling problem of the pathophysiology behind a peripheral genesis of migraine pain--or more particularly the baffling problem of its absence. I examine a number of pathophysiological states and the effector mechanisms for these states and find most of them very plausible and that they are all supported by abundant evidence. However, this evidence is mostly indirect; to date the occurrence of any of the presumed pathological states has not been convincingly demonstrated. Furthermore, there is little evidence of increased trigeminal sensory traffic into the central nervous system during a migraine attack. The article also examines a number of observations and experimental programs used to bolster a theory of peripheral pathology and suggests reasons why they may in fact not bolster it. I suggest that a pathology, if one exists, may be in the brain and even that it may not be a pathology at all. Migraine headache might just happen because of random noise in an exquisitely sensitive and complex network. The article suggests an experimental program to resolve these issues.
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Affiliation(s)
- Geoffrey A Lambert
- Prince of Wales Clinical School, Faculty of Medicine, University of New South Wales, Australia
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15
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Sokolov AY, Lyubashina OA, Panteleev SS. The role of serotonin receptors in migraine headaches. NEUROCHEM J+ 2011. [DOI: 10.1134/s1819712411020085] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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16
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Balaban CD, Jacob RG, Furman JM. Neurologic bases for comorbidity of balance disorders, anxiety disorders and migraine: neurotherapeutic implications. Expert Rev Neurother 2011; 11:379-94. [PMID: 21375443 PMCID: PMC3107725 DOI: 10.1586/ern.11.19] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The comorbidity among balance disorders, anxiety disorders and migraine has been studied extensively from clinical and basic research perspectives. From a neurological perspective, the comorbid symptoms are viewed as the product of sensorimotor, interoceptive and cognitive adaptations that are produced by afferent interoceptive information processing, a vestibulo-parabrachial nucleus network, a cerebral cortical network (including the insula, orbitofrontal cortex, prefrontal cortex and anterior cingulate cortex), a raphe nuclear-vestibular network, a coeruleo-vestibular network and a raphe-locus coeruleus loop. As these pathways overlap extensively with pathways implicated in the generation, perception and regulation of emotions and affective states, the comorbid disorders and effective treatment modalities can be viewed within the contexts of neurological and psychopharmacological sites of action of current therapies.
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Furman JM, Marcus DA, Balaban CD. Rizatriptan reduces vestibular-induced motion sickness in migraineurs. J Headache Pain 2010; 12:81-8. [PMID: 20862509 PMCID: PMC3072502 DOI: 10.1007/s10194-010-0250-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2010] [Accepted: 08/12/2010] [Indexed: 12/18/2022] Open
Abstract
A previous pilot study suggested that rizatriptan reduces motion sickness induced by complex vestibular stimulation. In this double-blind, randomized, placebo-controlled study we measured motion sickness in response to a complex vestibular stimulus following pretreatment with either rizatriptan or a placebo. Subjects included 25 migraineurs with or without migraine-related dizziness (23 females) aged 21–45 years (31.0 ± 7.8 years). Motion sickness was induced by off-vertical axis rotation in darkness, which stimulates both the semicircular canals and otolith organs of the vestibular apparatus. Results indicated that of the 15 subjects who experienced vestibular-induced motion sickness when pretreated with placebo, 13 showed a decrease in motion sickness following pretreatment with rizatriptan as compared to pretreatment with placebo (P < 0.02). This significant effect was not seen when subjects were exposed to more provocative vestibular stimulation. We conclude that the serotonin agonist, rizatriptan, reduces vestibular-induced motion sickness by influencing serotonergic vestibular-autonomic projections.
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Affiliation(s)
- Joseph M Furman
- Department of Otolaryngology, Eye and Ear Institute, University of Pittsburgh School of Medicine, 203 Lothrop Street, Pittsburgh, PA 15213, USA.
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19
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Gupta S, Villalón CM. The relevance of preclinical research models for the development of antimigraine drugs: focus on 5-HT(1B/1D) and CGRP receptors. Pharmacol Ther 2010; 128:170-90. [PMID: 20655327 DOI: 10.1016/j.pharmthera.2010.06.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Accepted: 06/25/2010] [Indexed: 01/08/2023]
Abstract
Migraine is a complex neurovascular syndrome, causing a unilateral pulsating headache with accompanying symptoms. The past four decades have contributed immensely to our present understanding of migraine pathophysiology and have led to the introduction of specific antimigraine therapies, much to the relief of migraineurs. Pathophysiological factors culminating into migraine headaches have not yet been completely deciphered and, thus, pose an additional challenge for preclinical research in the absence of any direct experimental marker. Migraine provocation experiments in humans use a head-score to evaluate migraine, as articulated by the volunteer, which cannot be applied to laboratory animals. Therefore, basic research focuses on different symptoms and putative mechanisms, one at a time or in combination, to validate the hypotheses. Studies in several species, utilizing different preclinical approaches, have significantly contributed to the two antimigraine principles in therapeutics, namely: 5-HT(1B/1D) receptor agonists (known as triptans) and CGRP receptor antagonists (known as gepants). This review will analyze the preclinical experimental models currently known for the development of these therapeutic principles, which are mainly based on the vascular and/or neurogenic theories of migraine pathogenesis. These include models based on the involvement of cranial vasodilatation and/or the trigeminovascular system in migraine. Clearly, the preclinical strategies should involve both approaches, while incorporating the newer ideas/techniques in order to get better insights into migraine pathophysiology.
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Affiliation(s)
- Saurabh Gupta
- Dept. of Neurology, Glostrup Research Institute, Glostrup Hospital, Faculty of Health Science, University of Copenhagen, Ndr. Ringvej 69, DK-2600 Glostrup, Copenhagen, Denmark.
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20
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Andreou AP, Summ O, Charbit AR, Romero-Reyes M, Goadsby PJ. Animal models of headache: from bedside to bench and back to bedside. Expert Rev Neurother 2010; 10:389-411. [PMID: 20187862 DOI: 10.1586/ern.10.16] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In recent years bench-based studies have greatly enhanced our understanding of headache pathophysiology, while facilitating the development of new headache medicines. At present, established animal models of headache utilize activation of pain-producing cranial structures, which for a complex syndrome, such as migraine, leaves many dimensions of the syndrome unstudied. The focus on modeling the central nociceptive mechanisms and the complexity of sensory phenomena that accompany migraine may offer new approaches for the development of new therapeutics. Given the complexity of the primary headaches, multiple approaches and techniques need to be employed. As an example, recently a model for trigeminal autonomic cephalalgias has been tested successfully, while by contrast, a satisfactory model of tension-type headache has been elusive. Moreover, although useful in many regards, migraine models are yet to provide a more complete picture of the disorder.
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Affiliation(s)
- Anna P Andreou
- Headache Group - Department of Neurology, University of California, San Francisco, San Francisco, CA 94115, USA
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21
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Jeong HJ, Chenu D, Johnson EE, Connor M, Vaughan CW. Sumatriptan inhibits synaptic transmission in the rat midbrain periaqueductal grey. Mol Pain 2008; 4:54. [PMID: 19014464 PMCID: PMC2588575 DOI: 10.1186/1744-8069-4-54] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Accepted: 11/11/2008] [Indexed: 01/22/2023] Open
Abstract
Background There is evidence to suggest that the midbrain periaqueductal grey (PAG) has a role in migraine and the actions of the anti-migraine drug sumatriptan. In the present study we examined the serotonergic modulation of GABAergic and glutamatergic synaptic transmission in rat midbrain PAG slices in vitro. Results Serotonin (5-hydroxytriptamine, 5-HT, IC50 = 142 nM) and the selective serotonin reuptake inhibitor fluoxetine (30 μM) produced a reduction in the amplitude of GABAA-mediated evoked inhibitory postsynaptic currents (IPSCs) in all PAG neurons which was associated with an increase in the paired-pulse ratio of evoked IPSCs. Real time PCR revealed that 5-HT1A, 5-HT1B, 5-HT1D and 5-HT1F receptor mRNA was present in the PAG. The 5-HT1A, 5-HT1B and 5-HT1D receptor agonists 8-OH-DPAT (3 μM), CP93129 (3 μM) and L694247 (3 μM), but not the 5-HT1F receptor agonist LY344864 (1 – 3 μM) inhibited evoked IPSCs. The 5-HT (1 μM) induced inhibition of evoked IPSCs was abolished by the 5-HT1B antagonist NAS181 (10 μM), but not by the 5-HT1A and 5-HT1D antagonists WAY100135 (3 μM) and BRL15572 (10 μM). Sumatriptan also inhibited evoked IPSCs with an IC50 of 261 nM, and reduced the rate, but not the amplitude of spontaneous miniature IPSCs. The sumatriptan (1 μM) induced inhibition of evoked IPSCs was abolished by NAS181 (10 μM) and BRL15572 (10 μM), together, but not separately. 5-HT (10 μM) and sumatriptan (3 μM) also reduced the amplitude of non-NMDA mediated evoked excitatory postsynaptic currents (EPSCs) in all PAG neurons tested. Conclusion These results indicate that sumatriptan inhibits GABAergic and glutamatergic synaptic transmission within the PAG via a 5-HT1B/D receptor mediated reduction in the probability of neurotransmitter release from nerve terminals. These actions overlap those of other analgesics, such as opioids, and provide a mechanism by which centrally acting 5-HT1B and 5-HT1D ligands might lead to novel anti-migraine pharmacotherapies.
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Affiliation(s)
- Hyo-Jin Jeong
- Pain Management Research Institute, Kolling Institute of Medical Research, Northern Clinical School, The University of Sydney at Royal North Shore Hospital, NSW 2065, Australia.
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Abstract
We tested the idea that migraine triggers cause cortical activation, which disinhibits craniovascular sensation through the nucleus raphe magnus (NRM) and thus produces the headache of migraine. Stimulation of the dura mater and facial skin activated neurons in the NRM and the trigeminal nucleus. Stimulation of the NRM caused suppression of responses of trigeminal neurons to electrical and mechanical stimulation of the dura mater, but not of the skin. This suppression was antagonized by the iontophoretic application of the 5-HT1B/1D receptor antagonist GR127935 to trigeminal neurons. Migraine trigger factors were simulated by cortical spreading depression (CSD) and light flash. Activity of neurons in the NRM was inhibited by these stimuli. Multiple waves of CSD antagonized the inhibitory effect of NRM stimulation on responses of trigeminal neurons to dural mechanical stimulation but not to skin mechanical stimulation. The cortico-NRM-trigeminal neuraxis might provide a target for a more universally effective migraine prophylactic treatment.
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Affiliation(s)
- GA Lambert
- Institute of Neurological Sciences, University of New South Wales & Prince of Wales Hospital, Randwick, Australia
| | - KL Hoskin
- Institute of Neurological Sciences, University of New South Wales & Prince of Wales Hospital, Randwick, Australia
| | - AS Zagami
- Institute of Neurological Sciences, University of New South Wales & Prince of Wales Hospital, Randwick, Australia
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24
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Samsam M, Coveñas R, Ahangari R, Yajeya J, Narváez J. Role of neuropeptides in migraine: where do they stand in the latest expert recommendations in migraine treatment? Drug Dev Res 2007. [DOI: 10.1002/ddr.20193] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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25
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Lambert GA. Looking in the wrong place? The search for an ideal migraine preventative. Drug Dev Res 2007. [DOI: 10.1002/ddr.20204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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Arulmani U, Gupta S, VanDenBrink AM, Centurión D, Villalón CM, Saxena PR. Experimental migraine models and their relevance in migraine therapy. Cephalalgia 2006; 26:642-59. [PMID: 16686903 DOI: 10.1111/j.1468-2982.2005.01082.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Although the understanding of migraine pathophysiology is incomplete, it is now well accepted that this neurovascular syndrome is mainly due to a cranial vasodilation with activation of the trigeminal system. Several experimental migraine models, based on vascular and neuronal involvement, have been developed. Obviously, the migraine models do not entail all facets of this clinically heterogeneous disorder, but their contribution at several levels (molecular, in vitro, in vivo) has been crucial in the development of novel antimigraine drugs and in the understanding of migraine pathophysiology. One important vascular in vivo model, based on an assumption that migraine headache involves cranial vasodilation, determines porcine arteriovenous anastomotic blood flow. Other models utilize electrical stimulation of the trigeminal ganglion/nerve to study neurogenic dural inflammation, while the superior sagittal sinus stimulation model takes into account the transmission of trigeminal nociceptive input in the brainstem. More recently, the introduction of integrated models, namely electrical stimulation of the trigeminal ganglion or systemic administration of capsaicin, allows studying the activation of the trigeminal system and its effect on the cranial vasculature. Studies using in vitro models have contributed enormously during the preclinical stage to characterizing the receptors in cranial blood vessels and to studying the effects of several putative antimigraine agents. The aforementioned migraine models have advantages as well as some limitations. The present review is devoted to discussing various migraine models and their relevance to antimigraine therapy.
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Affiliation(s)
- U Arulmani
- Department of Pharmacology, Cardiovascular Research Institute COEUR, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, the Netherlands
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27
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Abstract
The basic CNS neuropharmacology of naratriptan is reviewed here. Naratriptan is a second-generation triptan antimigraine drug, developed at a time when CNS activity was thought not to be relevant to its therapeutic effect in migraine. It was, however, developed to be a more lipid-soluble, more readily absorbed and less readily metabolized variant on preexisting triptans and these variations conferred on it a higher CNS profile. Naratriptan is a 5-HT(1B/1D) receptor agonist with a highly selective action on migraine pain and nausea, without significant effect on other pain or even other trigeminal pain. Probable sites of therapeutic action of naratriptan include any or all of: the cranial vasculature; the peripheral terminations of trigeminovascular sensory nerves; the first-order synapses of the trigeminovascular sensory system; the descending pain control system; and the nuclei of the thalamus. Naratriptan may prevent painful dilatation of intracranial vessels or reverse such painful dilatation. Naratriptan can prevent the release of sensory peptides and inhibit painful neurogenic vasodilatation of intracranial blood vessels. At the first order synapse of the trigeminal sensory system, naratriptan can selectively suppress neurotransmission from sensory fibers from dural and vascular tissue, while sparing transmission from other trigeminal fibers, probably through inhibition of neuropeptide transmitter release. In the periaqueductal gray matter and in the nucleus raphe magnus, naratriptan selectively activates inhibitory neurons which project to the trigeminal nucleus and spinal cord and which exert inhibitory influences on trigeminovascular sensory input. Naratriptan has also a therapeutic effect on the nausea of migraine, possibly exerting its action at the level of the nucleus tractus solitarius via the same mechanisms by which it inhibits trigeminovascular nociceptive input. The incidence of naratriptan-induced adverse effects in the CNS is low and it is not an analgesic for pain other than that of vascular headache. In patients receiving selective serotonin uptake inhibitors (SSRIs) naratriptan may cause serotonin syndrome-like behavioral side effects. The mechanism of action involved in the production of behavioral and other CNS side effects of naratriptan is unknown.
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Affiliation(s)
- Geoffrey A Lambert
- Institute of Neurological Sciences, The Prince of Wales Hospital, Randwick NSW 2031, Australia.
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28
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Shields KG, Storer RJ, Akerman S, Goadsby PJ. Calcium channels modulate nociceptive transmission in the trigeminal nucleus of the cat. Neuroscience 2005; 135:203-12. [PMID: 16084658 DOI: 10.1016/j.neuroscience.2004.08.054] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Revised: 08/10/2004] [Accepted: 08/11/2004] [Indexed: 11/25/2022]
Abstract
Clinical observations and genetic studies have suggested a role for high-threshold voltage-dependent calcium channels (VDCCs) in the pathogenesis of migraine. This study investigated the role of P/Q-, L- and N-type VDCCs in post-synaptic action potential generation in trigeminovascular nociceptive afferents in the trigeminocervical complex (TCC) of the cat in vivo. Trigeminovascular nociceptive afferents were identified in the TCC by electrical stimulation of the superior sagittal sinus. Forty-six cell bodies were identified by their response to microiontophoresis of l-glutamate and their bipolar action potential shape. Blockade of VDCCs was accomplished by microiontophoresis of omega-agatoxin IVa/TK (P/Q-), omega-conotoxin GVIa (N-) and calciseptine (L-type). Non-selective antagonism was studied using cadmium ions. Non-selective blockade of high threshold VDCC with cadmium resulted in a reduction in l-glutamate-evoked neuronal activity (P=0.01). Blockade of P/Q: TK- (P<0.001), IVA- (P=0.007), L- (P<0.001) and N-type (P<0.001) VDCCs resulted in significant reductions in post-synaptic action potential generation in response to l-glutamate. High threshold VDCCs, including P/Q-, L- and N-type VDCCs, can therefore modulate nociceptive transmission in the trigeminocervical complex in vivo. We discuss the evidence to suggest a role for VDCCs in the pathophysiology of primary headache disorders, and how abnormalities of function may contribute to their pathogenesis.
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Affiliation(s)
- K G Shields
- Headache Group, Institute of Neurology and The National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK
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29
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Abstract
Calcitonin gene-related peptide (CGRP) is a potent neuromodulator that is expressed in the trigeminovascular system and is released into the cranial circulation in various primary headaches. CGRP is released in migraine, cluster headache and paroxysmal hemicrania. The blockade of its release is associated with the successful treatment of acute migraine and cluster headache. CGRP receptor blockade has recently been shown to be an effective acute anti-migraine strategy and is non-vasoconstricting in terms of the mechanism of action. The prospect of a non-vasoconstricting therapy for acute migraine offers a real opportunity to patients, and perhaps more importantly, provides a therapeutic rationale to reinforce migraine as a neurological disorder.
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Affiliation(s)
- Peter J Goadsby
- Headache Group, Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK.
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Lambert GA, Hoskin KL, Zagami AS. Nitrergic and glutamatergic neuronal mechanisms at the trigeminovascular first-order synapse. Neuropharmacology 2004; 47:92-105. [PMID: 15165837 DOI: 10.1016/j.neuropharm.2004.03.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2003] [Revised: 02/19/2004] [Accepted: 03/01/2004] [Indexed: 11/22/2022]
Abstract
Nitric oxide (NO) donors such as glyceryl trinitrate cause headache, which suggests involvement of NO in trigeminovascular sensory processing. Sensory transmission at first-order synapses is believed to involve glutamate and the question arises as to whether it is also involved in trigeminovascular sensation and whether it might interact with nitrergic mechanisms. We investigated these questions at the first central synapse in the trigeminovascular sensory system of the cat. Neuronal action potentials in the trigeminal nucleus were recorded while the superior sagittal sinus (SSS) or facial receptive field (RF) were stimulated electrically. Drugs, including the neuronal excitant glutamate, were applied to neurons via microiontophoresis. Results were obtained from 152 neurons activated with A-delta latencies by SSS stimulation and by glutamate. The NO donor S-nitrosoglutathione (SNOG, 50 nA) was applied iontophoretically to 41 neurons during SSS stimulation and 13 neurons during pulsatile glutamate ejection. Responses to both modes of stimulation were enhanced by SNOG; the proportion of neurons enhanced was 56% to SSS stimulation and 59% to glutamate. The inhibitor of nitric oxide synthase (NOS), N(omega)-propyl-L-arginine (p-ARG, 50 nA) was applied iontophoretically to 17 neurons during stimulation of SSS and to 10 neurons during pulsatile glutamate ejection. Responses to both stimuli were suppressed by p-ARG: The proportion of neurons suppressed were: to SSS stimulation 59% and to glutamate 80%. Microiontophoretic ejection of eletriptan (50 nA) reversibly suppressed responses of neurons to SSS stimulation, to RF electrical stimulation and to pulsatile iontophoretic application of glutamate. This suppression of responses was antagonised by the concurrent local iontophoretic application of the 5-HT1B/1D receptor antagonist GR127935 or by concurrent iontophoretic application of the selective 5-HT1D receptor antagonist BRL155732. These results suggest that glutamatergic mechanisms are important in sensory transmission in the trigeminovascular system and that they can be modulated by nitrergic and serotonergic mechanisms.
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Affiliation(s)
- Geoffrey Andrew Lambert
- Department of Neurology, Institute of Neurological Sciences, Prince of Wales Hospital, The University of New South Wales, G39 Clinical Sciences Building, Randwick, NSW 2031, Australia.
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Bartsch T, Knight YE, Goadsby PJ. Activation of 5-HT1B/1D receptor in the periaqueductal gray inhibits nociception. Ann Neurol 2004; 56:371-81. [PMID: 15349864 DOI: 10.1002/ana.20193] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
It is considered that the site of action of the abortive antimigraine compounds acting at serotonin, 5-HT(1B/1D,) receptors (triptans) is the trigeminovascular system. We tested whether there is a non-trigeminal site of action. The 5-HT(1B/1D) agonist, naratriptan, was microinjected into the ventrolateral periaqueductal gray (vlPAG), and activity in the trigeminal nucleus caudalis (TNC) was monitored. Recordings were made from 20 nociceptive neurons in the dorsal horn of the TNC that received convergent input from the dura mater and face. Responses of neurons to dural, facial cutaneous and corneal stimulation were studied before and after injection of naratriptan. Naratriptan decreased the excitability to electrical stimulation of the dura mater as the A-fiber response decreased by 24 +/- 4.1% (p < 0.001) and the C-fiber response decreased by 42 +/- 8.2% (p < 0.001). Spontaneous activity was decreased by 38 +/- 7.5% (p < 0.001). After injection, the mechanical thresholds of the dura mater increased from (n = 14, p < 0.01). Responses to stimulation of the face and cornea were not altered by injection of naratriptan. These results suggest that 5-HT(1B/1D) receptor activation in the vlPAG activates descending pain-modulating pathways that inhibit dural, but not facial and corneal nociceptive input. These findings have implications for the understanding of the action of triptans in migraine and cluster headache, suggesting that brain loci other than the trigeminal nucleus may play a role in the clinical action of triptans.
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Affiliation(s)
- T Bartsch
- Headache Group, Institute of Neurology and The National Hospital for Neurology and Neurosurgery, Queen Square, London, United Kingdom
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Lambert GA, Boers PM, Hoskin KL, Donaldson C, Zagami AS. Suppression by eletriptan of the activation of trigeminovascular sensory neurons by glyceryl trinitrate. Brain Res 2002; 953:181-8. [PMID: 12384251 DOI: 10.1016/s0006-8993(02)03283-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The effect of intracarotid arterial infusions of glyceryl trinitrate (GTN), a substance known to precipitate vascular headache, on the spontaneous activity of trigeminal neurons with craniovascular input was studied in cats. Cats were anaesthetised with alpha-chloralose, immobilised and artificially ventilated. The superior sagittal sinus (SSS) was isolated and stimulated electrically. Facial receptive fields (RF) were also stimulated. Single neurons were recorded from the trigeminal nucleus caudalis with a metal microelectrode equipped with six glass barrels for microiontophoresis. Infusions of GTN were administered via a catheter inserted retrogradely into the common carotid artery through the lingual artery. Infusions of GTN (mean rate 19+/-7, range 5-100 microg kg(-1) min(-1), in a volume of 2 ml min(-1)) increased the spontaneous discharge rate of second-order neurons which received dural and facial sensory input to 429+/-80% of control. Iontophoretic application of the 5-HT(1B/1D) receptor agonist eletriptan (50 nA) at the peak of the response decreased the discharge rate of neurons towards pre-GTN control levels. In the presence of continuous iontophoretic application of the 5-HT(1B/1D) receptor antagonist GR127935, the decrease in discharge rate caused by eletriptan was antagonised. We conclude (1) that GTN activates craniovascular sensory pathways at a site at, or peripheral to, the second-order neuron and that such an action may account for at least the acute-onset headache induced by GTN and (2) that the antimigraine agent eletriptan is able to selectively suppress noxious sensory information from the dura, induced by GTN, via an action at 5-HT(1B/1D) receptors.
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Affiliation(s)
- G A Lambert
- Institute of Neurological Sciences, The Prince Henry and Prince of Wales Hospitals, University of New South Wales, Australia.
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