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Merighi A. The histology, physiology, neurochemistry and circuitry of the substantia gelatinosa Rolandi (lamina II) in mammalian spinal cord. Prog Neurobiol 2018; 169:91-134. [PMID: 29981393 DOI: 10.1016/j.pneurobio.2018.06.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 06/07/2018] [Accepted: 06/30/2018] [Indexed: 02/06/2023]
Abstract
The substantia gelatinosa Rolandi (SGR) was first described about two centuries ago. In the following decades an enormous amount of information has permitted us to understand - at least in part - its role in the initial processing of pain and itch. Here, I will first provide a comprehensive picture of the histology, physiology, and neurochemistry of the normal SGR. Then, I will analytically discuss the SGR circuits that have been directly demonstrated or deductively envisaged in the course of the intensive research on this area of the spinal cord, with particular emphasis on the pathways connecting the primary afferent fibers and the intrinsic neurons. The perspective existence of neurochemically-defined sets of primary afferent neurons giving rise to these circuits will be also discussed, with the proposition that a cross-talk between different subsets of peptidergic fibers may be the structural and functional substrate of additional gating mechanisms in SGR. Finally, I highlight the role played by slow acting high molecular weight modulators in these gating mechanisms.
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Affiliation(s)
- Adalberto Merighi
- Department of Veterinary Sciences, University of Turin, Largo Paolo Braccini 2, I-10095 Grugliasco (TO), Italy.
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The calcitonin gene-related peptide receptor antagonist MK-8825 decreases spinal trigeminal activity during nitroglycerin infusion. J Headache Pain 2013; 14:93. [PMID: 24256609 PMCID: PMC3845525 DOI: 10.1186/1129-2377-14-93] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 11/16/2013] [Indexed: 01/04/2023] Open
Abstract
Background Calcitonin gene-related peptide (CGRP) and nitric oxide (NO) are regarded as key mediators in migraine and other primary headaches. Migraineurs respond to infusion of nitroglycerin with delayed headaches, and inhibition of CGRP receptors has been shown to be effective in migraine therapy. In animal experiments nitrovasodilators like nitroglycerin induced increases in spinal trigeminal activity, which were reversed after inhibition of CGRP receptors. In the present study we asked if CGRP receptor inhibition can also prevent spinal trigeminal activity induced by nitroglycerin. Methods In isoflurane anaesthetised rats extracellular recordings were made from neurons in the spinal trigeminal nucleus with meningeal afferent input. The non-peptide CGRP receptor inhibitor MK-8825 (5 mg/kg) dissolved in acidic saline (pH 3.3) was slowly infused into rats one hour prior to prolonged glyceryl trinitrate (nitroglycerin) infusion (250 μg/kg/h for two hours). Results After infusion of MK-8825 the activity of spinal trigeminal neurons with meningeal afferent input did not increase under continuous nitroglycerin infusion but decreased two hours later below baseline. In contrast, vehicle infusion followed by nitroglycerin was accompanied by a transient increase in activity. Conclusions CGRP receptors may be important in an early phase of nitroglycerin-induced central trigeminal activity. This finding may be relevant for nitroglycerin-induced headaches.
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Messlinger K, Lennerz JK, Eberhardt M, Fischer MJ. CGRP and NO in the Trigeminal System: Mechanisms and Role in Headache Generation. Headache 2012; 52:1411-27. [DOI: 10.1111/j.1526-4610.2012.02212.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Panneton WM, Gan Q, Livergood RS. A trigeminoreticular pathway: implications in pain. PLoS One 2011; 6:e24499. [PMID: 21957454 PMCID: PMC3177822 DOI: 10.1371/journal.pone.0024499] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Accepted: 08/11/2011] [Indexed: 01/18/2023] Open
Abstract
Neurons in the caudalmost ventrolateral medulla (cmVLM) respond to noxious stimulation. We previously have shown most efferent projections from this locus project to areas implicated either in the processing or modulation of pain. Here we show the cmVLM of the rat receives projections from superficial laminae of the medullary dorsal horn (MDH) and has neurons activated with capsaicin injections into the temporalis muscle. Injections of either biotinylated dextran amine (BDA) into the MDH or fluorogold (FG)/fluorescent microbeads into the cmVLM showed projections from lamina I and II of the MDH to the cmVLM. Morphometric analysis showed the retrogradely-labeled neurons were small (area 88.7 µm(2)±3.4) and mostly fusiform in shape. Injections (20-50 µl) of 0.5% capsaicin into the temporalis muscle and subsequent immunohistochemistry for c-Fos showed nuclei labeled in the dorsomedial trigeminocervical complex (TCC), the cmVLM, the lateral medulla, and the internal lateral subnucleus of the parabrachial complex (PBil). Additional labeling with c-Fos was seen in the subnucleus interpolaris of the spinal trigeminal nucleus, the rostral ventrolateral medulla, the superior salivatory nucleus, the rostral ventromedial medulla, and the A1, A5, A7 and subcoeruleus catecholamine areas. Injections of FG into the PBil produced robust label in the lateral medulla and cmVLM while injections of BDA into the lateral medulla showed projections to the PBil. Immunohistochemical experiments to antibodies against substance P, the substance P receptor (NK1), calcitonin gene regulating peptide, leucine enkephalin, VRL1 (TPRV2) receptors and neuropeptide Y showed that these peptides/receptors densely stained the cmVLM. We suggest the MDH- cmVLM projection is important for pain from head and neck areas. We offer a potential new pathway for regulating deep pain via the neurons of the TCC, the cmVLM, the lateral medulla, and the PBil and propose these areas compose a trigeminoreticular pathway, possibly the trigeminal homologue of the spinoreticulothalamic pathway.
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Affiliation(s)
- W Michael Panneton
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri, United States of America.
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Chacur M, Matos R, Alves A, Rodrigues A, Gutierrez V, Cury Y, Britto L. Participation of neuronal nitric oxide synthase in experimental neuropathic pain induced by sciatic nerve transection. Braz J Med Biol Res 2010; 43:367-76. [DOI: 10.1590/s0100-879x2010007500019] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2009] [Accepted: 03/01/2010] [Indexed: 11/21/2022] Open
Affiliation(s)
- M. Chacur
- Universidade de São Paulo; Universidade de São Paulo
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Bardoni R, Ghirri A, Zonta M, Betelli C, Vitale G, Ruggieri V, Sandrini M, Carmignoto G. Glutamate-mediated astrocyte-to-neuron signalling in the rat dorsal horn. J Physiol 2010; 588:831-46. [PMID: 20083514 DOI: 10.1113/jphysiol.2009.180570] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
By releasing neuroactive agents, including proinflammatory cytokines, prostaglandins and neurotrophins, microglia and astrocytes are proposed to be involved in nociceptive transmission, especially in conditions of persistent, pathological pain. The specific action on dorsal horn neurons of agents released from astrocytes, such as glutamate, has been, however, poorly investigated. By using patch-clamp and confocal microscope calcium imaging techniques in rat spinal cord slices, we monitored the activity of dorsal horn lamina II neurons following astrocyte activation. Results obtained revealed that stimuli that triggered Ca(2+) elevations in astrocytes, such as the purinergic receptor agonist BzATP and low extracellular Ca(2+), induce in lamina II neurons slow inward currents (SICs). Similarly to SICs triggered by astrocytic glutamate in neurons from other central nervous system regions, these currents (i) are insensitive to tetrodotoxin (TTX), (ii) are blocked by the NMDA receptor (NMDAR) antagonist d-AP5, (iii) lack an AMPA component, and (iv) have slow rise and decay times. Ca(2+) imaging also revealed that astrocytic glutamate evokes NMDAR-mediated episodes of synchronous activity in groups of substantia gelatinosa neurons. Importantly, in a model of peripheral inflammation, the development of thermal hyperalgesia and mechanical allodynia was accompanied by a significant increase of spontaneous SICs in dorsal horn neurons. The NMDAR-mediated astrocyte-to-neuron signalling thus represents a novel pathway that may contribute to the control of central sensitization in pathological pain.
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Affiliation(s)
- Rita Bardoni
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41100 Modena, Italy.
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Eberhardt M, Neeb L, Vogel EM, Tiegs G, Reuter U, Messlinger K, Fischer MJM. Glyceroltrinitrate facilitates stimulated CGRP release but not gene expression of CGRP or its receptor components in rat trigeminal ganglia. Neuropeptides 2009; 43:483-9. [PMID: 19864020 DOI: 10.1016/j.npep.2009.09.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Revised: 08/24/2009] [Accepted: 09/16/2009] [Indexed: 01/24/2023]
Abstract
Nitric oxide (NO) donors induce delayed headaches in migraineurs. In a corresponding rat model NO donors cause delayed ongoing activity in central trigeminal neurons which process intracranial afferent input. Cellular models indicate that NO may increase the release or production of calcitonin gene-related peptide (CGRP), a key mediator in primary headaches. CGRP release from intact isolated trigeminal ganglia of adult male Wistar rats was investigated in vitro. Exposure to high NO donor concentrations did not affect basal or stimulated CGRP release. After a two hour infusion of the NO donor glyceroltrinitrate (250microg/kg/h), however, inflammatory mediators-induced CGRP release was 80% higher compared to control animals. Administration of the soluble guanylate cyclase inhibitor ODQ or the application of 8Br-cGMP revealed a cGMP-independent mechanism. In four groups of separate experiments total mRNA was extracted from rat trigeminal ganglia up to 6h after glyceroltrinitrate or saline infusion. Gene expression of CGRP and the CGRP-receptor components, receptor activity-modifying protein 1, receptor component protein and calcitonin receptor-like receptor was measured by quantitative RT-PCR. Glyceroltrinitrate infusion did not change mRNA levels of these genes compared to infusion of saline. The present data suggest that prolonged increase in NO levels facilitates stimulated CGRP release from trigeminal ganglion neurons. The underlying mechanism appears to be independent of the cGMP pathway and not to interact with CGRP in the trigeminal ganglion. Delayed headaches induced by NO may change CGRP or CGRP-receptor expression.
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Affiliation(s)
- Mirjam Eberhardt
- Institute of Physiology and Experimental Pathophysiology, Erlangen, Germany
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Sciatic nerve transection increases gluthatione antioxidant system activity and neuronal nitric oxide synthase expression in the spinal cord. Brain Res Bull 2009; 80:422-7. [DOI: 10.1016/j.brainresbull.2009.08.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 08/02/2009] [Accepted: 08/06/2009] [Indexed: 12/11/2022]
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Abstract
Challenges have emerged following the revival of nitric oxide (NO) from 'something old', a simple gas derived from nitrogen and oxygen with a role in the early stages of evolution, into 'something new', an endogenously formed biological mediator regulating a wide variety of physiological functions. Although pain is a common sensation, it encompasses multiple neurobiologic components, of which NO is only one. In pain research, the study of NO is complicated by convoluted problems related mostly to the effects of NO, which are pro- or anti-nociceptive depending on the circumstances. This dual function reflects the multi-faceted roles of the NO molecule described in physiology. This review covers current information about NO and its implications in pain mechanisms. In addition, it follows the pain pathways, demonstrating the role of NO in peripheral nociceptive transmission as well in central sensitization. This knowledge may provide the scientific basis for developing new drugs that are indicated for different types of pain, drugs that may be related to the chemical links of NO. A comprehensive approach to understanding the effects of NO will help clinicians identify novel agents that combine the pharmacological profile of native drugs with a controllable manner of NO release. Inhibitors of NO synthesis may have analgesic effects and would be of interest for treating inflammatory and neuropathic pain. Unfortunately, only a few of these compounds have reached the stage of clinical pain trials.
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Affiliation(s)
- A Miclescu
- Department of Surgical Sciences/Anesthesiology and Intensive Care Medicine, Uppsala University Hospital, Uppsala, Sweden.
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The effects of the TRPV1 receptor antagonist SB-705498 on trigeminovascular sensitisation and neurotransmission. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 2009; 380:311-25. [PMID: 19690836 DOI: 10.1007/s00210-009-0437-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2009] [Revised: 06/01/2009] [Accepted: 07/12/2009] [Indexed: 10/20/2022]
Abstract
This report examines the effect of the transient receptor potential vanilloid 1 receptor antagonist SB-705498 on neurotransmission and inflammation-induced sensitisation in the trigeminovascular sensory system. A single-neuron electrophysiological animal model for neurovascular head pain was used to evaluate dural and facial noxious inputs and the effects of SB-705498 administered by intravenous (i.v.) injection. Electrical and mechanical stimulation of the dura mater and the facial skin activated second-order neurons in the trigeminal nucleus caudalis of cats, with A-delta latencies. Intravenous injection of SB-705498 (2 mg kg(-1)) produced a slowly developing and long-lasting suppression of responses to dural and skin stimulation. Maximum suppression occurred by 1 h and reached 41% for dura and 24% for skin. Intravenous injection of drug vehicle did not produce significant suppression of responses to stimulation of either dura or skin. Intravenous injection of SB-705498 produced a brief and small rise in blood pressure and dural blood flow, which both returned to normal before suppression of the responses to stimulation became manifest. Application of "inflammatory soup" to the dura mater produced a pronounced increase in dural blood flow and induced a slowly developing increase in the responses of neurons to both electrical and mechanical stimulations of their facial and dural receptive fields. This sensitisation reached a maximum in 60-90 min, at which time responses had risen to approximately twice that of control levels seen before the application of inflammatory soup. Intravenous injection of SB-705498 subsequent to the development of sensitisation produced a slowly developing, prolonged and statistically significant reversal of the sensitisation induced by inflammatory soup. Maximum reversal of sensitisation to electrical stimulation occurred by 150-180 min, when responses had fallen to, or below, control levels. At 70-85 min following injection of SB-705498, the responses of previously sensitised neurons to mechanical stimulation of dura mater and facial receptive field had also returned to near control levels. SB-705498 was also able to prevent the development of sensitisation; application of inflammatory soup to the dura mater induced a slowly developing increase in the responses of neurons to electrical stimulation of the skin and dura mater in cats which had received an i.v. injection of vehicle for SB-705498 but not in cats which had received the active drug. Blood levels of SB-705498 were maximal immediately following i.v. injection and declined over the following 2 h. Significant brain levels of SB-705498 were maintained for up to 9 h. These results suggest that SB-705498 may be an effective suppressant and reversal agent of the sensitisation to sensory input which follows inflammation in the trigeminovascular sensory distribution but may not be particularly useful in blocking primary pain processes such as migraine headache. SB-705498 could thus potentially prevent, modify or reverse the cutaneous trigeminal allodynia seen in certain migraine conditions, especially "transformed" migraine.
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Schlechtweg PM, Röder J, Fischer MJM, Neuhuber W, Messlinger K. Increase in NADPH-Diaphorase-Positive and Neuronal NO Synthase Immunoreactive Neurons in the Rat Spinal Trigeminal Nucleus Following Infusion of a NO Donor—Evidence for a Feed-Forward Process in NO Production Involved in Trigeminal Nociception. Cephalalgia 2009; 29:566-79. [DOI: 10.1111/j.1468-2982.2008.01791.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Nitric oxide (NO) donors, which cause delayed headaches in migraineurs, have been shown to activate central trigeminal neurons with meningeal afferent input in animal experiments. Previous reports indicate that this response may be due to up-regulation of NO-producing cells in the trigeminal brainstem. To investigate this phenomenon further, we determined nitric oxide synthase (NOS)-containing neurons in the rat spinal trigeminal nucleus (STN), the projection site of nociceptive trigeminal afferents, following infusion of the NO donor sodium nitroprusside (SNP). Barbiturate anaesthetized rats were infused intravenously with SNP (50 μg/kg) or vehicle for 20 min or 2 h, and after periods of 3–8 h fixed by perfusion. Cryostat sections of the medulla oblongata containing the caudal STN were histochemically processed for detection of nicotineamide adenine dinucleotide phosphate (NADPH)-diaphorase or immunohistochemically stained for NOS isoforms and examined by light and fluorescence microscopy. The number of neurons positive for these markers was determined. Various forms of neurons positive for NADPH-diaphorase or immunoreactive to neuronal NOS (nNOS) were found in superficial and deep laminae of the STN caudalis and around the central canal. Neurons were not immunopositive for endothelial (eNOS) or inducible (iNOS) NOS isoforms. The number of NADPH-diaphorase-positive neurons increased time dependently after SNP infusion by a factor of more than two. Likewise, the number of nNOS-immunopositive neurons was increased after SNP compared with vehicle infusion. Around the central canal the number of NADPH-diaphorase-positive neurons was slightly increased and the number of nNOS+ neurons not changed after SNP treatment. NO donors increase the number of neurons that produce NO in the STN, possibly by induction of nNOS expression. Increased NO production may facilitate neurotransmitter release and promote nociceptive transmission in the STN. This mechanism may explain the delayed increase in neuronal activity and headache after infusion of NO donors.
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Affiliation(s)
- PM Schlechtweg
- Institute of Radiology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - J Röder
- Institute of Physiology & Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - MJM Fischer
- Institute of Physiology & Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - W Neuhuber
- Institute of Anatomy, University of Erlangen-Nürnberg, Erlangen, Germany
| | - K Messlinger
- Institute of Physiology & Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
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Kulchitsky S, Fischer MJM, Messlinger K. Calcitonin Gene-Related Peptide Receptor Inhibition Reduces Neuronal Activity Induced by Prolonged Increase in Nitric Oxide in the Rat Spinal Trigeminal Nucleus. Cephalalgia 2009; 29:408-17. [DOI: 10.1111/j.1468-2982.2008.01745.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Infusion of nitric oxide (NO) donors is known to induce delayed attacks of migraine and cluster headache or aggravate tension-type headaches in patients suffering from these primary headaches. Previously we have reported that infusion of NO donors in the rat causes delayed neuronal activity in the spinal trigeminal nucleus, which parallels the above clinical observations. Suggesting that endogenous NO production is involved in the generation of primary headaches, we used this animal model of meningeal nociception to determine whether a prolonged increase in NO levels causes an increase in neuronal activity. In anaesthetized rats spinal trigeminal neurons with afferent input from the exposed dura were recorded. Continuous intravenous infusion of the NO donors sodium nitroprusside (25 μg/kg/h) or glycerol trinitrate (250 μg/ kg/h) for 2h induced a persisting increase in neuronal activity but no change in systemic blood pressure. In this activated trigeminal system the calcitonin gene-related peptide (CGRP) receptor antagonist BIBN4096BS (900 μg/ kg) was infused. Spinal trigeminal activity was significantly reduced within minutes and to a similar extent as previously reported in animals not treated with NO. Slow continuous NO infusion may be a model of the active headache phase, and inhibition of CGRP receptors can reverse the induced neuronal activity.
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Affiliation(s)
- S Kulchitsky
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - MJM Fischer
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - K Messlinger
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
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Messlinger K. Migraine: where and how does the pain originate? Exp Brain Res 2009; 196:179-93. [PMID: 19288089 DOI: 10.1007/s00221-009-1756-y] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Accepted: 02/24/2009] [Indexed: 02/03/2023]
Abstract
Migraine is a complex neurological disease with a genetic background. Headache is the most prominent and clinically important symptom of migraine but its origin is still enigmatic. Numerous clinical, histochemical, electrophysiological, molecular and genetical approaches form a puzzle of findings that slowly takes shape. The generation of primary headaches like migraine pain seems to be the consequence of multiple pathophysiological changes in meningeal tissues, the trigeminal ganglion, trigeminal brainstem nuclei and descending inhibitory systems, based on specific characteristics of the trigeminovascular system. This contribution reviews the current discussion of where and how the migraine pain may originate and outlines the experimental work to answer these questions.
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Affiliation(s)
- Karl Messlinger
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany.
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Characterizing intercellular signaling peptides in drug addiction. Neuropharmacology 2008; 56 Suppl 1:196-204. [PMID: 18722391 DOI: 10.1016/j.neuropharm.2008.07.036] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 07/23/2008] [Accepted: 07/28/2008] [Indexed: 11/23/2022]
Abstract
Intercellular signaling peptides (SPs) coordinate the activity of cells and influence organism behavior. SPs, a chemically and structurally diverse group of compounds responsible for transferring information between neurons, are broadly involved in neural plasticity, learning and memory, as well as in drug addiction phenomena. Historically, SP discovery and characterization has tracked advances in measurement capabilities. Today, a suite of analytical technologies is available to investigate individual SPs, as well as entire intercellular signaling complements, in samples ranging from individual cells to entire organisms. Immunochemistry and in situ hybridization are commonly used for following preselected SPs. Discovery-type investigations targeting the transcriptome and proteome are accomplished using high-throughput characterization technologies such as microarrays and mass spectrometry. By integrating directed approaches with discovery approaches, multiplatform studies fill critical gaps in our knowledge of drug-induced alterations in intercellular signaling. Throughout the past 35 years, the National Institute on Drug Abuse has made significant resources available to scientists that study the mechanisms of drug addiction. The roles of SPs in the addiction process are highlighted, as are the analytical approaches used to detect and characterize them.
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Milligan ED, Sloane EM, Watkins LR. Glia in pathological pain: a role for fractalkine. J Neuroimmunol 2008; 198:113-20. [PMID: 18547654 PMCID: PMC3289257 DOI: 10.1016/j.jneuroim.2008.04.011] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2008] [Accepted: 04/10/2008] [Indexed: 01/01/2023]
Abstract
Microglia and/or astrocytes play a significant role in the creation and maintenance of exaggerated pain states with inflammatory and/or neuropathic etiologies. The chemokine, fractalkine, has several functions, including the newly recognized role of mediating neuropathic pain conditions. Although constitutively expressed and released during inflammation, increased release of fractalkine binds to and activates microglia leading to pathological pain. We review the critical role of fractalkine in neuron-to-glial communication after peripheral nerve injury and inflammation and explore anti-inflammatory cytokines like interleukin-10 as a novel and effective approach for clinical pain control.
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Affiliation(s)
- E D Milligan
- Department of Neurosciences, University of New Mexico, Health Sciences Center, Albuquerque, NM 87131-0001 USA.
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Lennerz JK, Rühle V, Ceppa EP, Neuhuber WL, Bunnett NW, Grady EF, Messlinger K. Calcitonin receptor-like receptor (CLR), receptor activity-modifying protein 1 (RAMP1), and calcitonin gene-related peptide (CGRP) immunoreactivity in the rat trigeminovascular system: Differences between peripheral and central CGRP receptor distribution. J Comp Neurol 2008; 507:1277-99. [DOI: 10.1002/cne.21607] [Citation(s) in RCA: 249] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Lizarraga I, Chambers JP, Johnson CB. Synergistic depression of NMDA receptor-mediated transmission by ketamine, ketoprofen and L-NAME combinations in neonatal rat spinal cords in vitro. Br J Pharmacol 2007; 153:1030-42. [PMID: 18084314 DOI: 10.1038/sj.bjp.0707638] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Spinal N-methyl-D-aspartate (NMDA) receptor/cyclooxygenase (COX) and nitric oxide synthase (NOS) pathways play a major role in nociceptive processing, and influencing them simultaneously may induce synergistic analgesia. This study determined the spinal antinociceptive interactions between ketamine (NMDA receptor channel blocker), ketoprofen (COX inhibitor) and L-NAME (NOS inhibitor) combinations. EXPERIMENTAL APPROACH Using an in vitro neonatal rat spinal cord preparation, two A-fibre-mediated reflexes, the monosynaptic reflex (MSR) and the low-intensity excitatory postsynaptic potential (epsp), and one C-fibre-mediated reflex, the high-intensity epsp, were evoked electrically. The effect of drugs and drug combinations on these reflexes was assessed and the type of interaction determined by isobolographic analysis. KEY RESULTS Infusion of ketamine alone decreased all three reflexes. That of ketoprofen decreased both the low and the high-intensity epsp only. Infusion of L-NAME alone produced no significant effects. Co-infusion of fixed ratios of IC(40) fractions of both (ketamine+ketoprofen) and (ketamine+L-NAME) were synergistic for depressing the low and the high-intensity epsps. The interaction was sub-additive for both combinations on the MSR. The only significant effect for the (ketoprofen+L-NAME) combination was synergism on the high-intensity epsp. CONCLUSIONS AND IMPLICATIONS All three combinations synergistically depressed nociceptive spinal transmission, and both ketamine and ketoprofen and ketamine and L-NAME combinations did so with potentially decreased motor side effects. If such combination profiles also occur in vivo, the present findings raise the possibility of ultimate therapeutic exploitation of increased analgesia with fewer side effects.
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Affiliation(s)
- I Lizarraga
- Departamento de Fisiología y Farmacología, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, México D.F., Mexico.
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Ro JY, Lee J, Capra NF, Zhang Y. Role of soluble guanylate cyclase in the trigeminal subnucleus caudalis in capsaicin-induced muscle hypersensitivity. Brain Res 2007; 1184:141-8. [PMID: 17980861 DOI: 10.1016/j.brainres.2007.09.085] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Revised: 09/25/2007] [Accepted: 09/26/2007] [Indexed: 01/07/2023]
Abstract
Nitric oxide (NO) produces its effects by activating soluble guanylate cyclase (sGC). In the present study, we investigated the potential role of sGC in the subnucleus caudalis (Vc) in mediating masseter hypersensitivity under acute inflammatory condition in male Sprague-Dawley rats. First, our Western blot analysis revealed that sGC protein is reliably detected in the Vc. Subsequent immunohistochemical studies demonstrated that neuronal cell bodies in the superficial laminae of the Vc positively stained for sGC. Astrocytes in deeper lamina of the Vc also showed sGC immunoreactivity. We then tested whether intrathecal administration of sGC inhibitors, methylene blue (MB), and ODQ, in the Vc, attenuates masseter hypersensitivity induced by intramuscular injection of capsaicin. Intrathecal MB or ODQ significantly blocked the capsaicin-induced reduction of mechanical threshold to noxious stimulation of the masseter. These data indicate that the NO-sGC pathway in the Vc is involved in mediating orofacial muscle hypersensitivity under acute inflammatory conditions.
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Affiliation(s)
- Jin Y Ro
- Department of Biomedical Sciences, Program in Neuroscience, University of Maryland Baltimore, School of Dentistry, Baltimore, MD 21201, USA.
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20
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Allbutt HN, Siddall PJ, Keay KA. Contusive spinal cord injury evokes localized changes in NADPH-d activity but extensive changes in Fos-like immunoreactivity in the rat. J Anat 2007; 211:352-70. [PMID: 17584182 PMCID: PMC2375816 DOI: 10.1111/j.1469-7580.2007.00765.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The histological detection of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d), a marker for nitric oxide-producing cells, was used to evaluate ongoing changes in the neural biochemistry of the rat spinal cord 1 week following contusive spinal cord injury (SCI). In addition, the immunohistochemical detection of the immediate-early gene c-fos was used to identify basal patterns of neural activity at this time. The numbers and laminar locations of NADPH-d- and c-fos-positive cells were examined in spinal segments adjacent to the site of injury (T12-S3) as well as those distant from the injury (C3-C5) in both SCI and un-injured rats. Our data show that contusive SCI results in a significant reduction in NADPH-d labelling in the superficial dorsal horn, and a significant increase in NADPH-d expression in small bipolar neurons and large motoneurons in the ventral horn at the site of the injury. In spinal segments distant to the injury site (C3-C5), NADPH-d activity did not differ from that of uninjured controls. Furthermore, significant reductions in the levels of c-fos expression were observed in SCI rats, in spinal segments both at and distant to the site of injury for all spinal laminae. The only exception was a dramatic increase observed in the sacral parasympathetic nucleus. These data suggest that increased NADPH-d expression is related to conditions specific to the site of injury, whereas the changes in c-fos expression probably indicate more global changes in neuronal activity following SCI.
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Affiliation(s)
- Haydn N Allbutt
- School of Medical Sciences (Anatomy & Histology), University of Sydney, Australia.
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21
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Salio C, Lossi L, Ferrini F, Merighi A. Neuropeptides as synaptic transmitters. Cell Tissue Res 2006; 326:583-98. [PMID: 16847638 DOI: 10.1007/s00441-006-0268-3] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Accepted: 05/31/2006] [Indexed: 12/20/2022]
Abstract
Neuropeptides are small protein molecules (composed of 3-100 amino-acid residues) that have been localized to discrete cell populations of central and peripheral neurons. In most instances, they coexist with low-molecular-weight neurotransmitters within the same neurons. At the subcellular level, neuropeptides are selectively stored, singularly or more frequently in combinations, within large granular vesicles. Release occurs through mechanisms different from classical calcium-dependent exocytosis at the synaptic cleft, and thus they account for slow synaptic and/or non-synaptic communication in neurons. Neuropeptide co-storage and coexistence can be observed throughout the central nervous system and are responsible for a series of functional interactions that occur at both pre- and post-synaptic levels. Thus, the subcellular site(s) of storage and sorting mechanisms into different neuronal compartments are crucial to the mode of release and the function of neuropeptides as neuronal messengers.
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Affiliation(s)
- Chiara Salio
- Dipartimento di Morfofisiologia Veterinaria and Rita Levi Montalcini Center for Brain Repair, Via Leonardo da Vinci 44, 10095, Grugliasco (TO), Italy
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22
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Ding JD, Weinberg RJ. Localization of soluble guanylyl cyclase in the superficial dorsal horn. J Comp Neurol 2006; 495:668-78. [PMID: 16506200 PMCID: PMC2597089 DOI: 10.1002/cne.20901] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Nitric oxide (NO) has been implicated in pain processing at the spinal level, but the mechanisms mediating its effects remain unclear. In the present work, we studied the organization of the major downstream effector of NO, soluble guanylyl cyclase (sGC), in the superficial dorsal horn of rat. Almost all neurokinin 1 (NK1) receptor-positive neurons in lamina I (a major source of ascending projections) were strongly immunopositive for sGC. Many local circuit neurons in laminae I-II also stained for sGC, but less intensely. Numerous fibers, presumably of unmyelinated primary afferent (C fiber) origin, stained for calcitonin gene-related peptide or isolectin B4, but none of these was immunopositive for sGC. These data, along with immunoelectron microscopy results, imply that unmyelinated primary afferent fibers terminating in the superficial dorsal horn lack sGC. Double labeling showed that neuronal nitric oxide synthase (nNOS) seldom colocalized with sGC, but nNOS-positive structures were frequently closely apposed to sGC-positive structures, suggesting that in the superficial dorsal horn NO acts mainly in a paracrine manner. Our data suggest that the NK1 receptor-positive projection neurons in lamina I are a major target of NO released in superficial dorsal horn. NO may also influence local circuit neurons, but it does not act on unmyelinated primary afferent terminals via sGC.
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Affiliation(s)
- Jin-Dong Ding
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Richard J. Weinberg
- Department of Cell and Developmental Biology, University of North Carolina, Chapel Hill, NC 27599, USA
- Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Correspondence to: Richard J. Weinberg, Department of Cell and Developmental Biology, University of North Carolina, CB7090, Chapel Hill, NC 27599; Phone: (919) 966−1277; Fax: (919) 966−1856; E-mail:
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23
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Necker R. Embryonic development of choline acetyltransferase and nitric oxide synthase in the spinal cord of pigeons and chickens with special reference to the superficial dorsal horn. ACTA ACUST UNITED AC 2005; 210:145-54. [PMID: 16044318 DOI: 10.1007/s00429-005-0018-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/24/2005] [Indexed: 12/18/2022]
Abstract
The superficial dorsal horn of birds as well as mammals contains both cholinergic and nitrergic neuronal structures as evident from the presence of the synthesizing enzymes such as choline acetyltransferase and nitric oxide synthase, which is an NADPH diaphorase. In the rat, both systems develop only postnatally. Rats are altricial at birth whereas pigeons and chickens are semiprecocial or precocial, respectively, at the time of hatching. Immunocytochemical studies of choline acetyltransferase and nitric oxide synthase in the developing avian spinal cord (starting with embryonic day 12 of 18 in the pigeon and 14 of 21 in the chicken) showed that both systems are well developed in the superficial dorsal horn at the time of hatching in both avian species. In the pigeon, choline acetyltransferase-positive superficial dorsal horn neurons appear only on the day of hatching (E18), whereas nitric oxide synthase-positive neurons can be first detected at stage E14. In the chicken, nitric oxide synthase-positive neurons are present already at stage E14, whereas choline acetyltransferase-positive neurons appear at stage E20. Autonomic and somatic motor neurons show adult-like choline acetyltransferase-immunoreactivity and/or nitric oxide synthase-immunoreactivity at the earliest stages investigated. It is concluded that the stage of maturation at birth or hatching plays an important role in the development of superficial dorsal horn cholinergic and nitrergic systems.
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Affiliation(s)
- R Necker
- Lehrstuhl für Tierphysiologie, Ruhr-Universität Bochum, 44780, Bochum, Germany.
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24
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Nomoto S, Shibata M, Iriki M, Riedel W. Role of afferent pathways of heat and cold in body temperature regulation. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2004; 49:67-85. [PMID: 15549421 DOI: 10.1007/s00484-004-0220-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2003] [Revised: 05/22/2004] [Accepted: 05/22/2004] [Indexed: 05/24/2023]
Abstract
The detection of surface and internal temperatures is achieved by axons terminating at lamina I of the spinal dorsal horn, otherwise approached only by nociceptive afferents. Recent advances in thermal physiology research have disclosed that temperature-sensitive ion channels belonging to the "transient receptor potential" family exist in the peripheral sensory neurons and in the brain. Thermosensory, nociceptive and polymodal afferents project to different thalamic nuclei, and specific pathways to the insular cortex evoke the conscious experience of thermal sensation. The posterior insular region represents discriminative thermal sensation, while the largest correlation with subjective ratings of temperature is located in the orbitofrontal and anterior insular cortex. The insular cortex forms an integrative part of the limbic system and is closely tied with the hypothalamus, the amygdala, the anterior cingulate cortex and the orbitofrontal cortex and emerges as the main coordinator of behavioral, autonomic and endocrine responses to both non-noxious and noxious thermal stimuli. The firing rate of warm and cold receptors is not altered by pyrogens. A strong correlation between the onset of fever and production of superoxide by macrophages following the injection of pyrogens implicates reactive oxygen species as elicitors of fever, a hypothesis strengthened by the observation that oxygen radical scavengers or thiol reductants act as antipyretics. Oxidative stress appears to be sensed by the brain and a likely structure for its detection may be the redox-sensitive site of the N-methyl-D-aspartate (NMDA) receptor for glutamate, in that oxidation of this site causes fever while its reduction lowers body temperature, effects which are abrogated by specific NMDA receptor blockers.
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Affiliation(s)
- Shigeki Nomoto
- Tokyo Metropolitan Institute of Gerontology, 173-0015 Tokyo, Japan.
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25
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Chacur M, Gutiérrez JM, Milligan ED, Wieseler-Frank J, Britto LRG, Maier SF, Watkins LR, Cury Y. Snake venom components enhance pain upon subcutaneous injection: an initial examination of spinal cord mediators. Pain 2004; 111:65-76. [PMID: 15327810 DOI: 10.1016/j.pain.2004.06.001] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Revised: 05/18/2004] [Accepted: 06/01/2004] [Indexed: 11/18/2022]
Abstract
Snakebites are a relevant public health problem in Central and South America. Snake bite envenomations cause intense pain, not relieved by anti-venom. The fangs of many species are short, causing subcutaneous injection. Fangs of larger species inflict subcutaneous or intramuscular envenomation. To understand pain induced by subcutaneous venom, this study examined spinal mechanisms involved in pain-enhancing effects of subcutaneous Lys49 and Asp49 secretory phospholipase-A(2) (sPLA2), two components of Bothrops asper snake venom showing highly different enzymatic activities. Unilateral intraplantar sPLA2-Lys49 (catalytically inactive) or sPLA2-Asp49 (catalytically active) into rat hindpaws each induced mechanical hyperalgesia (Randall-Selitto test), whereas only catalytically active sPLA2-Asp49 caused mechanical allodynia (von Frey test). Effects induced by both sPLA2s were inhibited by intrathecal fluorocitrate, a reversible glial metabolic inhibitor. In support, immunohistochemical analysis revealed activation of dorsal horn astrocytes and microglia after intraplantar injection of either sPLA2. Spinal proinflammatory cytokines, nitric oxide, and prostanoids each appear to be involved in the pain-enhancing effects of these sPLA2s. Blockade of interleukin-1 (IL1) inhibited hyperalgesia induced by both sPLA2s, while leaving allodynia unaffected. Blockade of tumor necrosis factor reduced responses to sPLA2-Asp49. An inhibitor of neuronal nitric oxide synthase, 7-nitroindazole (7-NI), inhibited hyperalgesia induced by both sPLA2s, without interfering with allodynia induced by sPLA2-Asp49. On the other hand, L-N(6)-(1-iminoethyl)lysine (L-NI), an inhibitor of the inducible nitric oxide synthase, did not alter any sPLA2-induced effect. Lastly, celecoxib, an inhibitor of cyclooxygenase-2, attenuated sPLA2 actions. These data provide the first evidence of spinal mediators involved in pain facilitation induced by subcutaneous venoms.
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Affiliation(s)
- Marucia Chacur
- Laboratório de Fisiopatologia, Instituto Butantan, Av. Vital Brazil, 1500, 05503-900 São Paulo, SP, Brazil
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26
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Zanchet EM, Longo I, Cury Y. Involvement of spinal neurokinins, excitatory amino acids, proinflammatory cytokines, nitric oxide and prostanoids in pain facilitation induced by Phoneutria nigriventer spider venom. Brain Res 2004; 1021:101-11. [PMID: 15328037 DOI: 10.1016/j.brainres.2004.06.041] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/27/2004] [Indexed: 12/19/2022]
Abstract
The major local symptom of Phoneutria nigriventer envenomation is an intense pain, which can be controlled by infiltration with local anesthetics or by systemic treatment with opioid analgesics. Previous work showed that intraplantar (i.pl) injection of Phoneutria nigriventer venom in rats induces hyperalgesia, mediated peripherally by tachykinin and glutamate receptors. The present study examined the spinal mechanisms involved in pain-enhancing effect of this venom. Intraplantar injection of venom into rat hind paw induced hyperalgesia. This phenomenon was inhibited by intrathecal (i.t.) injection of tachykinin NK1 (GR 82334) or NK2 (GR 94800) receptor antagonists, a calcitonin gene-related peptide (CGRP) receptor antagonist (CGRP8-37) and N-methyl-D-aspartate (NMDA; MK 801 and AP-5), non-NMDA ionotropic (CNQX), or metabotropic (AIDA and MPEP) glutamate receptor antagonists, suggesting the involvement of spinal neurokinins and excitatory amino acids. The role of proinflammatory cytokines, nitric oxide (NO), and prostanoids in spinally mediated pain facilitation was also investigated. Pharmacological blockade of tumour necrosis factor-alpha (TNFalpha) or interleukin-1beta (IL-1beta) reduced the hyperalgesic response to venom. Intrathecal injection of L-N6-(1-iminoethyl)lysine (L-NIL), but not of 7-nitroindazole (7-NI), inhibited hyperalgesia induced by the venom, indicating that NO, generated by the activity of the inducible form of nitric oxide synthase, also mediates this phenomenon. Furthermore, indomethacin, an inhibitor of cyclooxigenases (COX), or celecoxib, a selective inhibitor of COX-2, abolished venom-induced hyperalgesia, suggesting the involvement of spinal prostanoids in this effect. These data indicate that the spinal mechanisms of pain facilitation induced by Phoneutria nigriventer venom involves a plethora of mediators that may cooperate in the genesis of venom-induced central sensitization.
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Affiliation(s)
- Eliane Maria Zanchet
- Laboratório de Fisiopatologia, Instituto Butantan, Avenida Vital Brazil, 1500, 05503-900, São Paulo, SP, Brazil
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27
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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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28
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Schulte G, Robertson B, Fredholm BB, DeLander GE, Shortland P, Molander C. Distribution of antinociceptive adenosine A1 receptors in the spinal cord dorsal horn, and relationship to primary afferents and neuronal subpopulations. Neuroscience 2004; 121:907-16. [PMID: 14580941 DOI: 10.1016/s0306-4522(03)00480-9] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Adenosine can reduce pain and allodynia in animals and man, probably via spinal adenosine A1 receptors. In the present study, we investigate the distribution of the adenosine A1 receptor in the rat spinal cord dorsal horn using immunohistochemistry, in situ hybridization, radioligand binding, and confocal microscopy. In the lumbar cord dorsal horn, dense immunoreactivity was seen in the inner part of lamina II. This was unaltered by dorsal root section or thoracic cord hemisection. Confocal microscopy of the dorsal horn revealed close anatomical relationships but no or only minor overlap between A1 receptors and immunoreactivity for markers associated with primary afferent central endings: calcitonin gene-related peptide, or isolectin B4, or with neuronal subpopulations: mu-opioid receptor, neuronal nitric oxide synthase, met-enkephalin, parvalbumin, or protein kinase Cgamma, or with glial cells: glial fibrillary acidic protein. A few adenosine A1 receptor positive structures were double-labeled with alpha-amino-3-hydroxy-5-methyl-4-isoaxolepropionic acid glutamate receptor subunits 1 and 2/3. The results indicate that most of the adenosine A1 receptors in the dorsal horn are located in inner lamina II postsynaptic neuronal cell bodies and processes whose functional and neurochemical identity is so far unknown. Many adenosine A1 receptor positive structures are in close contact with isolectin B4 positive C-fiber primary afferents and/or postsynaptic structures containing components of importance for the modulation of nociceptive information.
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Affiliation(s)
- G Schulte
- Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
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29
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Merighi A, Carmignoto G, Gobbo S, Lossi L, Salio C, Vergnano AM, Zonta M. Neurotrophins in spinal cord nociceptive pathways. PROGRESS IN BRAIN RESEARCH 2004; 146:291-321. [PMID: 14699971 DOI: 10.1016/s0079-6123(03)46019-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Neurotrophins are a well-known family of growth factors for the central and peripheral nervous systems. In the course of the last years, several lines of evidence converged to indicate that some members of the family, particularly NGF and BDNF, also participate in structural and functional plasticity of nociceptive pathways within the dorsal root ganglia and spinal cord. A subpopulation of small-sized dorsal root ganglion neurons is sensitive to NGF and responds to peripheral NGF stimulation with upregulation of BDNF synthesis and increased anterograde transport to the dorsal horn. In the latter, release of BDNF appears to modulate or even mediate nociceptive sensory inputs and pain hypersensitivity. We summarize here the status of the art on the role of neurotrophins in nociceptive pathways, with special emphasis on short-term synaptic and intracellular events that are mediated by this novel class of neuromessengers in the dorsal horn. Under this perspective we review the findings obtained through an array of techniques in naïve and transgenic animals that provide insight into the modulatory mechanisms of BDNF at central synapses. We also report on the results obtained after immunocytochemistry, in situ hybridization, and monitoring intracellular calcium levels by confocal microscopy, that led to hypothesize that also NGF might have a direct central effect in pain modulation. Although it is unclear whether or not NGF may be released at dorsal horn endings of certain nociceptors in vivo, we believe that these findings offer a clue for further studies aiming to elucidate the putative central effects of NGF and other neurotrophins in nociceptive pathways.
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Affiliation(s)
- Adalberto Merighi
- Department of Veterinary Morphophysiology, Rita Levi-Montalcini Center for Brain Repair, Via Leonardo da Vinci 44, 10095 Grugliasco, Turin, Italy.
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30
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Milligan ED, Maier SF, Watkins LR. Review: neuronal-glial interactions in central sensitization. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1537-5897(03)00044-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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31
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Schulte D, Millar J. The effects of high- and low-intensity percutaneous stimulation on nitric oxide levels and spike activity in the superficial laminae of the spinal cord. Pain 2003; 103:139-50. [PMID: 12749968 DOI: 10.1016/s0304-3959(02)00443-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nitric oxide (NO) was measured using a new electrochemical method with a carbon fibre microelectrode at depths of up to 400 microm in the lumbar dorsal horn of the anaesthetised rat. The method allowed extracellular spike recording from single units together with the electrochemical recording at the same electrode. Thirty-six cells with low threshold cutaneous (brush/touch) or wide dynamic range receptive fields (brush/touch plus pinch) were studied. Adequate stimulation of the receptive fields did not alter the extracellular NO level for any cells. Percutaneous needle electrodes inserted into the receptive fields were used to stimulate the cells electrically. Twenty-one cells were stimulated using 10 mA current with 0.05 ms duration (low intensity) pulses to stimulate predominantly A-fibre afferents. Single shock stimuli gave short latency spike responses but no change in nitric oxide level. Tetanic bursts of stimuli (400 stimuli at 50 Hz) generated a burst of spikes (spike count 548+/-42) and a transient increase in NO (2.61+/-0.11 microM NO). Nitric oxide synthesis inhibition with N(G)-nitro-L-arginine methyl ester (L-NAME) nearly abolished the stimulus-evoked increase in nitric oxide and increased the response of the cells (spike count 694+/-34). However, the inhibition of nitric oxide synthesis had no effect on the receptive fields. Fifteen cells were stimulated with shocks using 5 ms pulses (high intensity), to recruit C-fibre afferents into the input volley. This more intense stimulation increased the evoked NO release to 3.63+/-0.15 microM and the spike response to 647+/-54 in control conditions. Following L-NAME, the evoked NO release was reduced and the evoked spike response was significantly decreased. These results show that tetanic activity in afferent fibres increases NO synthesis in the dorsal horn and that inhibition of nitric oxide synthesis may be associated with a selective attenuation of the spike responses to C-fibre inputs. NO may be necessary to maintain proper function of C-fibre afferent synapses when they are subjected to sustained or tetanic inputs.
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Affiliation(s)
- D Schulte
- Department of Anaesthesiology, University Hospital Eppendorf, Hamburg, Germany
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32
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Eckert WA, McNaughton KK, Light AR. Morphology and axonal arborization of rat spinal inner lamina II neurons hyperpolarized by mu-opioid-selective agonists. J Comp Neurol 2003; 458:240-56. [PMID: 12619079 DOI: 10.1002/cne.10587] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The ventral or inner region of spinal substantia gelatinosa (SG; lamina II(i)) is a heterogeneous sublamina important for the generation and maintenance of hyperalgesia and neuropathic pain. To test whether II(i) neurons can be hyperpolarized by the mu-opioid agonist [D-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin (DAMGO; 500 nM) and to address possible downstream consequences of mu-opioid-evoked inhibition of II(i) neurons, we combined in vitro whole-cell, tight-seal recording methods with fluorescent labeling of the intracellular tracer biocytin and confocal microscopy. Twenty-one of 23 neurons studied had identifiable axons. Nine possessed axons that projected ventrally into laminae III-V; six of these were hyperpolarized by DAMGO. Three of four neurons with identifiable axons that projected to lamina I were hyperpolarized by DAMGO. Most neurons could be classified as either islet cells or stalked cells. Five of nine labeled islet cells and only two of seven stalked cells were hyperpolarized by DAMGO. Three were stellate cells: one resembled a spiny cell and three could not be classified. DAMGO hyperpolarized each of the stellate cells, the spiny cell, and 1 of the unclassified cells. Our data support the hypothesis that part of the action of mu-opioid agonists involves the inhibition of interneurons that are part of a polysynaptic excitatory pathway from primary afferents to neurons in the deep and/or superficial dorsal horn.
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MESH Headings
- Afferent Pathways/cytology
- Afferent Pathways/drug effects
- Afferent Pathways/metabolism
- Analgesics, Opioid/pharmacology
- Animals
- Dendrites/drug effects
- Dendrites/metabolism
- Dendrites/ultrastructure
- Enkephalin, Ala(2)-MePhe(4)-Gly(5)-/pharmacology
- Female
- Interneurons/cytology
- Interneurons/drug effects
- Interneurons/metabolism
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Microscopy, Confocal
- Neural Inhibition/drug effects
- Neural Inhibition/physiology
- Pain/metabolism
- Pain/physiopathology
- Posterior Horn Cells/cytology
- Posterior Horn Cells/drug effects
- Posterior Horn Cells/metabolism
- Presynaptic Terminals/drug effects
- Presynaptic Terminals/metabolism
- Presynaptic Terminals/ultrastructure
- Rats
- Rats, Long-Evans
- Receptors, Opioid, delta/drug effects
- Receptors, Opioid, delta/metabolism
- Receptors, Opioid, kappa/drug effects
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/agonists
- Receptors, Opioid, mu/metabolism
- Synaptic Transmission/drug effects
- Synaptic Transmission/physiology
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Affiliation(s)
- William A Eckert
- Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, North Carolina 27599-7545, USA
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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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Staud R, Smitherman ML. Peripheral and central sensitization in fibromyalgia: pathogenetic role. Curr Pain Headache Rep 2002; 6:259-66. [PMID: 12095460 DOI: 10.1007/s11916-002-0046-1] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Characteristic symptoms of fibromyalgia syndrome include widespread pain, fatigue, sleep abnormalities, and distress. Patients with fibromyalgia show psychophysical evidence of mechanical, thermal, and electrical hyperalgesia. Peripheral and central abnormalities of nociception have been described in fibromyalgia. Important nociceptor systems in the skin and muscles seem to undergo profound changes in patients with fibromyalgia through unknown mechanisms. They include sensitization of vanilloid receptor, acid-sensing ion channel receptors, and purino-receptors. Tissue mediators of inflammation and nerve growth factors can excite these receptors and cause extensive changes in pain sensitivity, but patients with fibromyalgia lack consistent evidence for inflammatory soft tissue abnormalities. Therefore, recent investigations have focused on central nervous system mechanisms of pain in fibromyalgia.
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Affiliation(s)
- Roland Staud
- Division of Rheumatology and Clinical Immunology, University of Florida, PO Box 100221, Gainesville, FL 32610-0221, USA.
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Salio C, Fischer J, Franzoni MF, Conrath M. Pre- and postsynaptic localizations of the CB1 cannabinoid receptor in the dorsal horn of the rat spinal cord. Neuroscience 2002; 110:755-64. [PMID: 11934482 DOI: 10.1016/s0306-4522(01)00584-x] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Several lines of evidence show that endogenous and exogenous cannabinoids modulate pain transmission at the spinal level through specific cannabinoid-1 (CB1) receptors. Since anatomical data concerning spinal CB1 receptors are rather contradictory, we studied the cellular and subcellular localizations of the CB1 receptors by immunocytochemistry. Results show a dual pre- and postsynaptic localization of CB1 receptors. Presynaptic receptors are evidenced by the labeling of (1) heterogeneous dorsal root ganglion neurons and (2) axons of Lissauer's tract. Postsynaptic receptors are shown by the labeling of numerous interneurons in the outer part of lamina II. Double immunolabelings show that lamina II outer CB1 neurons, probably islet cells, may also contain GABA or nitric oxide synthase. Numerous CB1-containing neurons in lamina X are also immunostained with anti-nitric oxide synthase (NOS) antibody. Under the electron microscope, CB1 immunoreactivity is exclusively localized postsynaptically in both somatic and dendritic compartments. The absence of labeling on primary afferent axon terminals is discussed and compared to the absence of labeling on terminals or vesicle-containing dendrites of islet cells, where a presynaptic localization was expected according to data of the literature.
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Affiliation(s)
- C Salio
- Départment de Neurobiologie des Signaux Intercellulaires, Institut des Neurosciences, Université Pierre et Marie Curie, Paris, France
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Li JL, Dong YL, Kaneko T, Mizuno N. Direct projections from substance P-containing neurons to nitric oxide synthase-containing interneurons in the rat striatum. Neurosci Lett 2002; 318:133-6. [PMID: 11803117 DOI: 10.1016/s0304-3940(01)02494-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We reported previously that substance P (SP)-containing projection neurons (SP-PN) in the striatum emitted many axon collaterals within the striatum (J. Comp. Neurol. 388 (1997) 250), and that substantially all striatal interneurons showing immunoreactivity for nitric oxide synthase (NOS: synthetic enzyme for the freely-diffusible messenger nitric oxide) displayed immunoreactivity for SP receptor (NK1: NK-1-type tachykinin receptor; Neurosci. Lett. 310 (2001) 109). By combining immunohistochemistry for NOS with immunogold labeling for SP, the present study revealed that SP-immunoreactive axon terminals were in synaptic contact with NOS-immunoreactive aspiny neurons in the rat striatum, indicating that SP-PN in the striatum sent their axon collaterals to nitric oxide synthase-expressing interneurons (NOS-IN) in the striatum. On the basis of these present and previous data, possible synaptic and non-synaptic interactions between SP-PN and NOS-IN in the striatum were discussed.
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Affiliation(s)
- Jin Lian Li
- Department of Anatomy and K.K. Leung Brain Research Center, The Fourth Military Medical University, 710032, Xi'an, People's Republic of China
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37
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Abstract
The term neuropeptides commonly refers to a relatively large number of biologically active molecules that have been localized to discrete cell populations of central and peripheral neurons. I review here the most important histological and functional findings on neuropeptide distribution in the central nervous system (CNS), in relation to their role in the exchange of information between the nerve cells. Under this perspective, peptide costorage (presence of two or more peptides within the same subcellular compartment) and coexistence (concurrent presence of peptides and other messenger molecules within single nerve cells) are discussed in detail. In particular, the subcellular site(s) of storage and sorting mechanisms within neurons are thoroughly examined in the view of the mode of release and action of neuropeptides as neuronal messengers. Moreover, the relationship of neuropeptides and other molecules implicated in neural transmission is discussed in functional terms, also referring to the interactions with novel unconventional transmitters and trophic factors. Finally, a brief account is given on the presence of neuropeptides in glial cells.
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Affiliation(s)
- A Merighi
- Department of Veterinary Morphophysiology, Rita Levi-Montalcini Center for Brain Repair, University of Torino, UE, Italy.
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Woda A, Molat JL, Luccarini P. Low doses of N-methyl-D-aspartate antagonists in superficial laminae of medulla oblongata facilitate wind-up of convergent neurones. Neuroscience 2002; 107:317-27. [PMID: 11731106 DOI: 10.1016/s0306-4522(01)00359-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In this study, a trigeminal model was used in which high threshold C-fibre-evoked activities of convergent neurones located in the subnucleus oralis of the trigeminal complex are modulated through the superficial part, the substantia gelatinosa, of the subnucleus caudalis. The two subnuclei are located 3 mm apart, therefore, it was possible to inject dizocilpine, a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, into either the superficial or the deep parts of subnucleus caudalis without interfering with ongoing recording of convergent neurones in subnucleus oralis. A differential NMDA-dependent modulation of wind-up was observed according to the dose and the injection target. (1) The injections of small non-diffusible doses (0.12 microg) of dizocilpine into the superficial part of subnucleus caudalis facilitated wind-up. The effect peaked at 25 min with a mean increase above control of 173+/-31%. Injection (0.5 microg) of either the less active enantiomer dizocilpine or saline into superficial subnucleus caudalis had no significant effect on subnucleus oralis convergent neurones. This suggests that NMDA-dependent interneurones, probably located in substantia gelatinosa of subnucleus caudalis, exert, in normal conditions, an inhibitory control on wind-up of convergent subnucleus oralis neurones. (2) The injection of larger doses (0.5 microg) into the superficial part of subnucleus caudalis induced a predominant inhibitory effect on wind-up. The mean peak effect at 15 min was 46+/-7% compared to control (100%). Small and large doses of dizocilpine injected into the deep part of subnucleus caudalis had a predominant inhibitory effect. The inhibition of wind-up of subnucleus oralis neurones after injection of NMDA receptor antagonists in superficial or deep subnucleus caudalis indicates that wind-up may be due, at least in part, to NMDA activation at synapses that do not involve the recorded convergent neurones.
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Affiliation(s)
- A Woda
- Université d'Auvergne Clermont 1, U.F.R. d'Odontologie, Laboratoire de Physiologie Oro-Faciale Faculté de Chirurgie Dentaire, 11 Boulevard Charles-de-Gaulle, 63000 Clermont-Ferrand, France.
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Luccarini P, Sessle BJ, Woda A. Superficial and deep convergent nociceptive neurons are differentially affected by N-methyl-D-aspartate applied on the brainstem surface of the rat medullary dorsal horn. Neuroscience 2002; 107:311-6. [PMID: 11731105 DOI: 10.1016/s0306-4522(01)00360-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The activation of N-methyl-D-aspartate receptors is implicated in the spinal and trigeminal processing of nociceptive information conveyed by convergent (wide dynamic range) neurons and particularly in C-fiber-evoked responses elicited by repetitive and high-intensity electrical stimulation of the neuronal receptive field. In this study, the effects of intrathecal NMDA application on the electrically evoked nociceptive responses of trigeminal subnucleus caudalis convergent neurons have been investigated. The total C-fiber-evoked activity triggered by 30 successive stimuli was divided into two components: the C-fiber input response and the 'wind-up' response. Application of 0.1 microg (in 50 microl) of NMDA evoked a bi-directional effect on the total C-fiber-evoked activity of 19 neurons tested. A significant increase in the total C-fiber-evoked activity was observed 15-25 min after the NMDA application for nine neurons located in superficial laminae II and III. In contrast, a significant decrease in the total C-fiber-evoked activity was observed 5-25 min after the NMDA application for 10 neurons located more deeply, in lamina V. The NMDA-induced modifications seen in the total C-fiber-evoked activity were likely a reflection of a significant increase or decrease in neuronal activity evoked by the C-fiber input rather than wind-up of the responses since the latter was not significantly modified by the NMDA application. These results provide evidence for a possible inhibitory role for NMDA-dependent interneurons of the superficial laminae of the medullary dorsal horn on the nociceptive activity of deep convergent neurons.
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Affiliation(s)
- P Luccarini
- Laboratoire de Physiologie Oro-Faciale, UFR d'Odontologie, Université d'Auvergne, Clermont-Ferrand, France.
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40
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Vruwink M, Schmidt HH, Weinberg RJ, Burette A. Substance P and nitric oxide signaling in cerebral cortex: anatomical evidence for reciprocal signaling between two classes of interneurons. J Comp Neurol 2001; 441:288-301. [PMID: 11745651 DOI: 10.1002/cne.1413] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Parvalbumin-containing fast-spiking interneurons in the cerebral cortex exhibit widespread electrical coupling, as do somatostatin-containing low-threshold spiking interneurons. Besides the classical neurotransmitter gamma-aminobutyric acid, these cortical interneurons may also release various neuropeptides including substance P (SP), as well as the freely diffusible messenger nitric oxide (NO). To investigate whether these two networks of interneurons might interact via these nonclassical messengers, we performed immunocytochemistry for SP and NO signaling pathways in rat somatic sensory cortex. SP was found in a subset of parvalbumin-positive cells concentrated in layers IV and V, whereas its receptor, NK1, was found in a subset of somatostatin-containing neurons (and also, at much lower levels, in a disjoint subset of parvalbumin-containing neurons). Only 4% of SP-containing axon terminals were apposed to NK1-positive dendrites, suggesting that in the cerebral cortex, SP may act predominantly as a paracrine neuromediator. Nitric oxide synthase-I (NOS-I), the synthetic enzyme for NO, was found almost exclusively in NK1-positive neurons; 95% of intensely somatostatin/NK1-positive neurons were also positive for NOS-I, and 94% of NOS-positive neurons were also positive for NK1. Immunoreactivity for soluble guanylyl cyclase (the NO receptor) was at high levels in the apical dendrites of layer V pyramidal neurons and in parvalbumin/SP-positive neurons. These data point to a novel reciprocal chemical interaction between two inhibitory networks in the rat neocortex.
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Affiliation(s)
- M Vruwink
- School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599, USA
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41
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Jones MG, Lever I, Bingham S, Read S, McMahon SB, Parsons A. Nitric oxide potentiates response of trigeminal neurones to dural or facial stimulation in the rat. Cephalalgia 2001; 21:643-55. [PMID: 11531896 DOI: 10.1046/j.1468-2982.2001.00213.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Infusing glyceryl trinitrate as a donor molecule, we have used electrophysiological and c-fos immunostaining techniques to study the effects of nitric oxide on neurones in the nucleus trigeminalis caudalis. Following infusion of glyceryl trinitrate, responses of neurones to electrical stimulation of periorbital cutaneous afferents were potentiated and threshold for activation of neurones by stimulation of dural afferents was reduced. Expression of c-fos was unchanged by glyceryl trinitrate compared to saline controls. Intradermal injection of capsaicin in the periorbital area increased c-fos expression in nucleus trigeminalis caudalis; this was significantly potentiated by glyceryl trinitrate. These results suggest that, in the anaesthetized rat, glyceryl trinitrate alone may not acutely activate the trigeminovascular system to a significant degree at doses that cause headache and later trigger migraine headache in migraineurs. Nevertheless, it is susceptible to exogenous nitric oxide in that activation of trigeminal neurones through cutaneous or dural pathways is potentiated. This may in some measure underlie the pathogenesis of migraine headache.
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Affiliation(s)
- M G Jones
- Sensory Function Group, Centre for Neuroscience, Guy's, King's & St Thomas's Hospital Medical Schools, London, UK.
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42
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Reuss MH, Reuss S. Nitric oxide synthase neurons in the rodent spinal cord: distribution, relation to Substance P fibers, and effects of dorsal rhizotomy. J Chem Neuroanat 2001; 21:181-96. [PMID: 11312059 DOI: 10.1016/s0891-0618(01)00091-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The indirect immunofluorescent method was employed to investigate the distribution of neuronal nitric oxide synthase-like immunoreactivity(nNOS-LI) in the spinal cord of the golden hamster and to compare it to data obtained from rats. Immunoreactive neurons were found throughout the cervico-sacral extent in the dorsal horn (mainly in laminae I-III) and in the preganglionic autonomic regions, i.e., the sympathetic intermediolateral nucleus (IML), lateral funicle (LF), intercalated region (IC), the area surrounding the central canal (CA), and the sacral preganglionic parasympathetic cell group. While the distribution of immunoreactive cells was generally similar in both species, some differences were observed. For example in the hamster LF, a higher percentage of stained neurons was seen than in the IML, while the situation was rather inverse in the rat. In order to study the coincidence of nNOS-LI in the population of preganglionic sympathetic neurons (PSN) that innervate the superior cervical ganglion (SCG), these were identified by retrograde axonal transport of fluoro-gold (FG) following unilateral injection into the SCG. PSN were localized ipsilateral to the injection site mainly in the IML and LF of spinal segments C7-Th4. The portion of double-labeled neurons of the IML were lower in hamster (17% in C7, 34% in C8) of FG-labeled cells) than in rat (47% in C8, 77% in Th2), while in the LF of segments C8-Th2 in both species the majority of FG-neurons contained nNOS. While only very few double-labeled neurons were detected in the IC in hamster and rat, a striking difference was observed in the CA, where no double-labeled neurons were found in hamster, but up to 50% in rat. Double immunofluorescence detection of nNOS and substance P (SP) showed that in both the autonomic regions and the dorsal horn, SP-LI fibers and puncta were present in close spatial relationship to nNOS-LI cell bodies. These results were basically identical in the hamster and rat. Unilateral transection of the dorsal roots of segments C6-Th2 in rats resulted in a clear reduction of SP-LI structures in the dorsal horn 5 days after rhizotomy, but not in the autonomic regions. Compared to the unlesioned side, the numbers of nNOS-LI neurons in the superficial laminae of the dorsal horn were reduced to 32-46% in the lesioned segments, and to 53% and 87%, respectively, in the two segments cranial to the rhizotomized segments but remained unchanged caudally to the lesion. Numbers of nNOS-LI cell bodies in the autonomic regions were not altered following dorsal root transection. The present study provides data on the widespread distribution of nNOS in the spinal cord of golden hamster and describes the partial coincidence of the enzyme in PSN. The effects of dorsal rhizotomy on nNOS-LI neurons in the dorsal horn reveal that primary-afferent fibers provide a stimulatory influence on neurons of the dorsal horn to generate the gaseous neuroactive substance, nitric oxide.
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Affiliation(s)
- M H Reuss
- Department of Anatomy, School of Medicine, Johannes Gutenberg University, Saarstr. 19-21, D-55099, Mainz, Germany
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43
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Lambert GA, Donaldson C, Boers PM, Zagami AS. Activation of trigeminovascular neurons by glyceryl trinitrate. Brain Res 2000; 887:203-10. [PMID: 11134608 DOI: 10.1016/s0006-8993(00)02919-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The effect of intra-carotid arterial infusions of glyceryl trinitrate (GTN), a substance known to precipitate headache, including migraine, upon the spontaneous activity of trigeminal neurons with craniovascular input was studied in cats. Second-order craniovascular neurons which received sensory input from the superior sagittal sinus were recorded in the trigeminal nucleus caudalis. Infusions of GTN were administered via a catheter inserted retrogradely into the common carotid artery through the lingual artery. Infusions of GTN (100 microg kg(-1) min(-1) in a volume of 2 ml min(-1)) increased the mean basal discharge rate of all second-order neurons to 239+/-47% of control. GTN produced a fall in mean blood pressure, but there was no correlation between this fall and the changes in discharge rate. GTN infusions sensitised neurons to the effects of electrical stimulation of the superior sagittal sinus, but not to subsequent GTN infusions. Infusions of similar volumes of vehicle did not alter the discharge rate of neurons. We conclude 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.
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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, NSW 2036, Little Bay, Australia.
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44
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Hoheisel U, Unger T, Mense S. A block of spinal nitric oxide synthesis leads to increased background activity predominantly in nociceptive dorsal horn neurones in the rat. Pain 2000; 88:249-257. [PMID: 11068112 DOI: 10.1016/s0304-3959(00)00336-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Previous studies have shown that nitric oxide (NO) has a strong influence on the background (resting) activity of dorsal horn neurones. The background activity of dorsal horn neurones is generally assumed to be responsible for the presence of paraesthesia or spontaneous pain in patients depending on the functional type of neurones that are active. However, nothing is known about a possible selective action of NO - or a lack of NO - on a particular functional class of neurone. In the present study the background activity of lumbar dorsal horn neurones was examined in anaesthetized rats before and during spinal superfusion with L-NAME, an unspecific blocker of NO synthesis. The neurones were divided into five classes: (1) low-threshold mechanosensitive (LTM) cells with deep receptive fields (LTM deep units); (2) LTM cells with cutaneous receptive fields (LTM cutaneous units) (these two classes were considered to be non-nociceptive); (3) high-threshold mechanosensitive (HTM) deep cells; (4) HTM cutaneous cells; and (5) multireceptive (MR) cutaneous cells (the last three classes were assumed to be nociceptive). HTM neurones increased the frequency of their background activity significantly during L-NAME superfusion and 80% of the initially silent neurones became active after administration of the NOS blocker. MR neurones likewise increased their background activity. In contrast, the background activity of non-nociceptive (LTM) neurones was not significantly affected. The results support previous studies showing that NO has a tonic depressing effect on the background activity of dorsal horn neurones and demonstrate for the first time that this effect is largely restricted to nociceptive neurones. Therefore, a reduction in spinal NO synthesis which often occurs during a long-lasting peripheral lesion is likely to cause increased background activity in nociceptive neurones and thus might contribute to spontaneous pain in patients.
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Affiliation(s)
- U Hoheisel
- Institut für Pharmakologie im Klinikum der Universität Kiel, Hospitalstraße 4, D-24105 Kiel, Germany Institut für Anatomie und Zellbiologie III, Im Neuenheimer Feld 307, D-69120 Heidelberg, Germany
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45
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Booth BP, Tabrizi-Fard MA, Fung H. Calcitonin gene-related peptide-dependent vascular relaxation of rat aorta. An additional mechanism for nitroglycerin. Biochem Pharmacol 2000; 59:1603-9. [PMID: 10799659 DOI: 10.1016/s0006-2952(00)00290-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We investigated the involvement of calcitonin gene-related peptide (CGRP) in the vasodilatory mechanism of action of nitric oxide (NO) donors. The functional role of CGRP in NO donor-induced vasodilation of isolated rat aortic rings was determined by incubating these drugs with and without CGRP(8-37), a selective CGRP receptor antagonist. CGRP(8-37) (0.63 microM) induced rightward shifts in the vasodilatory concentration-response curves for nitroglycerin (NTG), Piloty's acid (PA), and SIN-1 (linsidomine). The EC(50) values for NTG, PA, and SIN-1 were increased by 8.3-, 5.2-, and 2.3-fold, respectively (P < 0.05). The release of CGRP from rat aorta in response to NTG and PA was measured specifically by radioimmunoassay. Thirty-minute incubations of NTG or PA with rat aorta induced 189.5 and 214.6% increases, respectively, in CGRP release when compared with the control (P < 0.05). The concentration-response curves of sodium nitroprusside (SNP), S-nitroso-acetylpenicillamine (SNAP), tetranitromethane (TNM), diethylamine NO complex (DEA-NO), and diethylenetriamine/nitric oxide adduct (DETA NONOate) were not inhibited significantly by CGRP(8-37) co-incubation (P 0.05). NO donors also were incubated with aortic strips, and NTG and PA alone induced significant formation of hydroxylamine, a NO(-) metabolite (232.4 and 364.9%, respectively, P < 0.05). These results indicate that only NTG and PA, and to a lesser extent SIN-1, stimulate the release of CGRP from the rat aorta, which subsequently contributes to the vasodilatory activity of these agents. The hydroxylamine formation suggests a possible link between NO(-) generation and CGRP release from the vascular wall.
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Affiliation(s)
- B P Booth
- Department of Pharmaceutics, School of Pharmacy, State University of New York at Buffalo, Buffalo, NY, USA.
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46
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Messlinger K, Suzuki A, Pawlak M, Zehnter A, Schmidt RF. Involvement of nitric oxide in the modulation of dural arterial blood flow in the rat. Br J Pharmacol 2000; 129:1397-404. [PMID: 10742295 PMCID: PMC1571976 DOI: 10.1038/sj.bjp.0703220] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. Nitric oxide (NO) has been proposed to be a key molecule in the pathogenesis of migraine pain and other headaches that are linked to vascular disorders. Several lines of evidence indicate that the meningeal vascularization is crucially involved in the generation of these headaches. In an experimental model in the rat a dominating role of calcitonin gene-related peptide (CGRP) in causing neurogenic vasodilatation and increased blood flow has been shown. The aim of the present study was to clarify the role of NO in this model with regard to the meningeal blood flow. 2. The blood flow in and around the medial meningeal artery (dural arterial flow) was recorded in the exposed parietal dura mater encephali of barbiturate anaesthetized rats using laser Doppler flowmetry. Local electrical stimulation of the dura mater (pulses of 0.5 ms delivered at 7.5 - 17.5 V and 5 or 10 Hz for 30 s) caused temporary increases in dural arterial flow for about 1 min that reached peaks of 1.6 - 2.6 times the basal flow. The effects of NO synthase (NOS) inhibitors on the basal flow and the electrically evoked increases in flow were examined. 3. Systemic (i. v.) administration of N(omega)-nitro-L-arginine methyl ester (L-NAME) at cumulative doses of 10 and 50 mg kg(-1) lowered the basal flow to 87 and 72%, respectively, of the control and reduced the evoked increases in blood flow to 82 and 44% on an average. Both these effects could partly be reversed by 300 mg kg(-1) L-arginine. The systemic arterial pressure was increased by L-NAME at both doses. Injection of the stereoisomer D-NAME at same doses did not change basal flow and evoked increases in flow. 4. 4. Topical application of L-NAME (10(-4) - 10(-2) M) was effective only at the highest concentration, which caused lowering of the basal blood flow to 78% of the control; the evoked increases in flow were not changed. Topical application of 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT), a specific inhibitor of the inducible NOS, at concentrations of 10(-4) - 10(-2) M lowered the basal flow to 89, 87.5 and 85%, respectively, but did not significantly change the evoked flow increases. Same concentrations of 7-nitroindazole monosodium salt (7-NINA), a specific inhibitor of the neuronal NOS, had no significant effects on basal flow and evoked increases in flow. 5. It is concluded that NO is involved in the maintenance of the basal level of dural arterial blood flow as well as in the electrically evoked flow increases, which have been shown to be mainly mediated by CGRP released from dural afferent fibres. The most important source of NO is probably the endothelium of dural arterial vessels. The synergistic effect of NO and CGRP on the stimulated blood flow may be in part due to a NO mediated facilitation of the CGRP release.
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Affiliation(s)
- K Messlinger
- Department of Physiology, University of Würzburg, Röntgenring 9, D-97070 Würzburg, Germany
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Leong S, Liu H, Yeo J. Nitric oxide synthase and glutamate receptor immunoreactivity in the rat spinal trigeminal neurons expressing Fos protein after formalin injection. Brain Res 2000; 855:107-15. [PMID: 10650136 DOI: 10.1016/s0006-8993(99)02316-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Although recent studies implicated glutamate receptors and nitric oxide in nociception, much still needs to be known about their localisation in neurons involved in nociceptive transmission from the orofacial region. In this study, c-fos expression indicated by Fos immunohistochemistry in the caudal spinal trigeminal nucleus induced by subcutaneous injection of formalin into the lateral face of the rat was used as a marker for nociceptive neurons. The study sought to determine whether Fos-positive neurons express nitric oxide synthase, glutamate N-methyl-D-aspartate type receptor subunit 1, and glutamate alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid type receptor subunit 2/3; and whether they project to the thalamus. After formalin injection, many Fos-positive nuclei appeared in the superficial laminae of the ipsilateral trigeminal nucleus. Confocal laser scanning microscope revealed that almost all neurons with Fos immunofluorescent nuclei were colocalised with N-methyl-D-aspartate receptor 1, 94% with glutamate receptor 2/3 and 14% with nitric oxide synthase. Some of them were closely related to neurons labelled by nitric oxide synthase. Lastly, some of the Fos-positive neurons were labelled by tetramethylrhodamine-dextran injected into the trigeminothalamic tract or the thalamic region. The results suggested that activation of N-methyl-D-aspartate receptor 1 and glutamate receptor 2/3 upon glutamate release in response to noxious stimulation to the orofacial region might mediate c-fos expression in neurons involved in nociception. The expression of Fos in the neurons could also be mediated by nitric oxide produced from the same, as well as neighbouring neurons, when nociceptive stimulation persisted. Fos-positive neurons in the spinal trigeminal nucleus may project to the thalamus, relaying orofacial nociception to the higher sensory centre.
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Affiliation(s)
- S Leong
- Department of Anatomy, Faculty of Medicine, National University of Singapore, Lower Kent Ridge Road, Singapore, Singapore.
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