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Bista P, Imlach WL. Pathological Mechanisms and Therapeutic Targets for Trigeminal Neuropathic Pain. MEDICINES (BASEL, SWITZERLAND) 2019; 6:E91. [PMID: 31443547 PMCID: PMC6789505 DOI: 10.3390/medicines6030091] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/15/2019] [Accepted: 08/16/2019] [Indexed: 12/31/2022]
Abstract
Trigeminal neuropathic pain is a chronic pain condition caused by damage or inflammation of the trigeminal nerve or its branches, with both peripheral and central nervous system dysfunction contributing to the disorder. Trigeminal pain conditions present with diagnostic and therapeutic challenges to healthcare providers and often require multiple therapeutic approaches for pain reduction. This review will provide the overview of pathophysiology in peripheral and central nociceptive circuits that are involved in neuropathic pain conditions involving the trigeminal nerve and the current therapeutics that are used to treat these disorders. Recent advances in treatment of trigeminal pain, including novel therapeutics that target ion channels and receptors, gene therapy and monoclonal antibodies that have shown great promise in preclinical studies and clinical trials will also be described.
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Affiliation(s)
- Pawan Bista
- Department of Physiology & Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC 3800, Australia
| | - Wendy L Imlach
- Department of Physiology & Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC 3800, Australia.
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LIN M, LUO ZY, BAI BF, XU F, LU TJ. FLUID DYNAMICS ANALYSIS OF SHEAR STRESS ON NERVE ENDINGS IN DENTINAL MICROTUBULE: A QUANTITATIVE INTERPRETATION OF HYDRODYNAMIC THEORY FOR DENTAL PAIN. J MECH MED BIOL 2011. [DOI: 10.1142/s0219519411003983] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Noxious thermal and/or mechanical stimuli applied to dentine can cause fluid flow in dentinal microtubules (DMTs). The fluid flow induces shear stress (SS) on intradental nerve endings and may excite pulpal mechanoreceptors to generate dental pain sensation. There exist numerous studies on dental thermal pain, but few are mathematical. For this, we developed a computational fluid dynamics (CFD) model of dentinal fluid flow (DFF) in innervated DMTs. Based on this model, we systematically investigated the effects of various parameters (e.g., biological structure, DFF velocity, and fluid properties) on the SS experienced by intradental nerve endings and thus provide a quantitative interpretation to the hydrodynamic theory. The dimensions of biological structures, odontoblastic process (OP) movement, dentinal fluid velocity, and viscosity were found to have significant influences on the SS while dentinal fluid density showed negligible influence under conditions studied. The results indicate that: (i) dental pain study of animal models may not be directly applied to human being and the results may even vary from one person to another and (ii) OP movement caused by DFF changes the dimension of the space for the fluid flow, affecting thus the SS on nerve endings. The present work enables better understanding of the mechanisms underlying dental pain sensation and quantification of dental pain intensity resulted from clinical procedures such as dentine sensitivity testing and dental restorative processes.
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Affiliation(s)
- M. LIN
- Biomedical Engineering and Biomechanics Center, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - Z. Y. LUO
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University Xi'an 710049, P. R. China
| | - B. F. BAI
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University Xi'an 710049, P. R. China
| | - F. XU
- Biomedical Engineering and Biomechanics Center, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, P. R. China
- HST-Center for Biomedical Engineering, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - T. J. LU
- Biomedical Engineering and Biomechanics Center, School of Aerospace, Xi'an Jiaotong University, Xi'an 710049, P. R. China
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Wanachantararak S, Vongsavan N, Matthews B. Electrophysiological observations on the effects of potassium ions on the response of intradental nerves to dentinal tubular flow in the cat. Arch Oral Biol 2011; 56:294-305. [DOI: 10.1016/j.archoralbio.2010.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 09/29/2010] [Accepted: 10/05/2010] [Indexed: 10/18/2022]
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Abstract
In farm animal practice, there is often a clear tension between animal welfare and the economic basis of food animal production. Animal well-being is regularly compromised by the stringencies of intensive animal husbandry. Conditions such as infectious keratoconjunctivitis or ocular squamous cell carcinoma, while having negative effects on animal welfare, also have profoundly deleterious effects on animal production. This article discusses the welfare implications of the ocular conditions covered further in the following articles and how these affect treatment of these diseases.
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Affiliation(s)
- David L Williams
- Veterinary Ophthalmology and Animal Welfare, Department of Veterinary Medicine, University of Cambridge, Cambridge CB3 0ES, England, UK.
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Wu LA, Huang J, Wang W, Wang W, Li YQ, Wang XJ, Wu SX. Activation of GABAergic neurons following tooth pulp stimulation. J Dent Res 2010; 89:532-6. [PMID: 20332333 DOI: 10.1177/0022034510363231] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The functional impact of GABA (gamma-aminobutyric acid)ergic neurons in nociceptive transmission of the spinal trigeminal nucleus is not fully established. Using both the glutamic acid decarboxylase (GAD)(67)-green fluorescence protein (GFP) knock-in mouse and the tooth pulp stimulation model, we performed double-immunofluorescent histochemistry to determine the characteristics of GABAergic neuron activation in the spinal trigeminal nucleus. The number of Fos-positive GABAergic neuronal profiles was significantly increased 2 hrs after tooth pulp stimulation. The Fos/GFP double-labeled neurons were mainly present in superficial laminae of the spinal trigeminal subnucleus interpolaris-caudalis transition (Vi/Vc) and subnucleus caudalis (Vc) on the side ipsilateral to the stimulation. Subsequently, the number of double-labeled neurons decreased gradually and became comparable with that of the controls by 48 hrs. Our results provide direct morphological evidence that a subset of GABAergic neurons in the spinal trigeminal system was activated during tooth pulp stimulation.
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Affiliation(s)
- L-A Wu
- Department of Paediatric Dentistry, School of Stomatology, Fourth Military Medical University, No. 145 West Changle Road, Xi'an 710032, China
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Vongsavan N, Matthews B. The relationship between the discharge of intradental nerves and the rate of fluid flow through dentine in the cat. Arch Oral Biol 2007; 52:640-7. [PMID: 17303068 DOI: 10.1016/j.archoralbio.2006.12.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 12/08/2006] [Accepted: 12/13/2006] [Indexed: 11/19/2022]
Abstract
OBJECTIVE To investigate further the relationship between dentinal tubular flow and the discharge evoked in intradental nerves. DESIGN In anaesthetised cats, recordings were made of fluid flow through dentine during the application of hydrostatic pressure stimuli of 5 s duration in the range +500 to -500 mm Hg to exposed dentine and of the nerve impulses evoked by these stimuli. Single unit recordings were obtained from filaments dissected from the inferior alveolar nerve and multi-unit recordings, from the exposed dentine. RESULTS Of 20 single units tested, 10 (conduction velocities: 2.4-36.2 m s(-1)) responded to negative pressures and four of these, also to positive pressures. None responded to only positive pressures. The pressure thresholds of the units (single and multi-unit preparations) ranged from -100 to -500 and +100 to +500. In terms of flow (measured 1 s after the start of a stimulus) the thresholds ranged from 0.4 to 2.2 nl s(-1) mm(-2) exposed dentine with outward flow, and 0.4-2.1 nl s(-1) mm(-2) with inward flow. The outward flow per tubule at the threshold of the most sensitive units was estimated to be 21 fl s(-1) and the corresponding mean velocity of the contents of the dentinal tubules at their pulpal ends, 27 microm s(-1). Although the thresholds to outward and inward flow were similar, with outward flow the mean discharge rate increased with stimulus intensity; whereas with inward flow few impulses were evoked and the number was little affected by the stimulus intensity. CONCLUSION The transduction mechanism that generates impulses in hydrodynamic intradental afferents is much more responsive to outward than inward flow through the dentinal tubules, although the thresholds in both directions are similar.
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Affiliation(s)
- Noppakun Vongsavan
- Department of Physiology, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK.
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Chidchuangchai W, Vongsavan N, Matthews B. Sensory transduction mechanisms responsible for pain caused by cold stimulation of dentine in man. Arch Oral Biol 2006; 52:154-60. [PMID: 17109813 DOI: 10.1016/j.archoralbio.2006.09.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 09/04/2006] [Accepted: 09/11/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To determine the effects on the sensitivity of exposed dentine to cold that are produced when dentine is etched to remove the smear layer and when the tubules are blocked again with calcium oxalate. Separate in vitro observations were made on the effects of these procedures on fluid flow through the dentine. DESIGN The experiments were carried out on 24 premolars in 17 subjects. Dentine was exposed at the tip of the buccal cusp and cold stimuli were applied by placing the tip of an ice stick on the cavity floor for 5s under the following conditions: before etching the dentine, after etching, and after oxalate treatment. The subject indicated the intensity of any pain produced on a visual analogue scale (VAS). Fluid flow through the dentine was recorded under similar conditions in eight of the teeth in vitro. RESULTS The mean VAS score produced by the ice before etching was 21.3+/-19.5mm (S.D.). This increased significantly to 85.4+/-15.6mm after etching (P<0.01). After oxalate treatment, it decreased significantly to 8.5+/-13.3mm. The corresponding mean rates of fluid flow through dentine were 2.15+/-1.02, 1.55+/-0.84, and 2.29+/-1.28nL/smm(2) exposed dentine, respectively. The mean after etching was significantly less than the other two values (P<0.05). CONCLUSION If the pain was due to hydrodynamic receptors, their sensitivity to dentinal fluid flow changed when the tubules were opened or closed. Alternatively the pain was produced by receptors sensitive to some other change produced by the cold stimuli, such as specific cold receptors.
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Affiliation(s)
- Warungkana Chidchuangchai
- Department of Pharmacology, Faculty of Dentistry, Mahidol University, Yothi Street, Rajathavee, Bangkok 10400, Thailand
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Abstract
Intraoral splints are effective in migraine prevention. In this review, changes in the quality of life of migraineurs treated with a palatal nonoccluding splint were measured. Using the Migraine Specific Quality of Life Instrument (Version 2.1), it was found that the palatal nonoccluding splint significantly improved the quality of life of migraineurs. The role of the craniomandibular muscles in the pathophysiology of migraine is also discussed.
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Affiliation(s)
- Elliot Shevel
- The Headache Clinic, Suite 256, P Bag X2600, Houghton, 2014, South Africa.
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Ichikawa H, Fukuda T, Terayama R, Yamaai T, Kuboki T, Sugimoto T. Immunohistochemical localization of gamma and beta subunits of epithelial Na+ channel in the rat molar tooth pulp. Brain Res 2005; 1065:138-41. [PMID: 16297886 DOI: 10.1016/j.brainres.2005.10.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Revised: 10/03/2005] [Accepted: 10/11/2005] [Indexed: 11/19/2022]
Abstract
The distribution of gamma and beta subunits of epithelial Na(+) channel (ENaC), markers for low-threshold mechanoreceptors in peripheral tissues, was examined in the tooth pulp. In the root pulp, gammaENaC- and betaENaC-immunoreactive (IR) nerve fibers showed a thick smooth appearance. These nerve fibers ascended toward the pulp horn and formed subodontoblastic nerve plexuses. Immunoelectron microscopic method revealed that 63% of axons were immunoreactive for gammaENaC in the root pulp. Virtually all myelinated axons showed gammaENaC-IR (97%), whereas unmyelinated axons were mostly devoid of it (12%). These findings suggest that myelinated tooth pulp nociceptors respond to mechanical stimuli.
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Affiliation(s)
- H Ichikawa
- Department of Oral Function and Anatomy, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 700-8525, Japan.
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Borsook D, Burstein R, Becerra L. Functional imaging of the human trigeminal system: Opportunities for new insights into pain processing in health and disease. ACTA ACUST UNITED AC 2004; 61:107-25. [PMID: 15362156 DOI: 10.1002/neu.20085] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Peripheral inflammation or nerve damage result in changes in nervous system function, and may be a source of chronic pain. A number of animal studies have indicated that central neural plasticity, including sensitization of neurons within the spinal cord and brain, is part of the response to nervous system insult, and can result in the appearance of altered sensation, including pain. It cannot be assumed, however, that data obtained from animal models unambiguously reflects CNS changes that occur in humans. Currently, the only noninvasive approach to determining objective changes in neural processing and responsiveness within the CNS in humans is the use of functional imaging techniques. It is now possible to use functional magnetic resonance imaging (fMRI) to measure CNS activation in the trigeminal ganglion, spinal trigeminal nucleus, the thalamus, and the somatosensory cortex in healthy volunteers, in a surrogate model of hyperalgesia, and in patients with trigeminal pain. By offering a window into the temporal and functional changes that occur in the damaged nervous system in humans, fMRI can provide both insight into the mechanisms of normal and pathological pain and, potentially, an objective method for measuring altered sensation. These advances are likely to contribute greatly to the diagnosis and treatment of clinical pain conditions affecting the trigeminal system (e.g., neuropathic pain, migraine).
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Affiliation(s)
- David Borsook
- P.A.I.N. Group, Brain Imaging Center, McLean Hospital, 115 Mill Street, Belmont, Massachusetts 02478-9106, USA.
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Le Bars D. The whole body receptive field of dorsal horn multireceptive neurones. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 2002; 40:29-44. [PMID: 12589904 DOI: 10.1016/s0165-0173(02)00186-8] [Citation(s) in RCA: 288] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Multireceptive neurones are found in the spinal dorsal horn and may be projection neurones and/or interneurones for polysynaptic reflexes. The cutaneous receptive field of a multireceptive neurone exhibits a gradient of sensitivity with the centre responding to any mechanical stimulus, including hair movements and light touch, while the periphery responds only to noxious stimuli. These neurones also receive signals from viscera, muscles and joints. This convergence of inputs means that multireceptive neurones are continuously capturing all the information from both the interface with the external environment (the skin) and the internal milieu (the viscera, muscles, etc.). This information constitutes a 'basic somaesthetic activity' that could help the somatosensory system build a 'global representation of the body'. In addition to be seen as a global entity, the output of multireceptive neurones should be understood in dynamic terms since the size of the peripheral fields of the individual neurones may change, as a result of the plasticity of both excitatory and inhibitory segmental processes. Furthermore, the activity of these neurones can be inhibited from most of the remaining parts of the body via supraspinal mechanisms. These diffuse noxious inhibitory controls (DNIC) are triggered by peripheral A delta- and C-fibres, involve brain structures confined to the caudal-most part of the medulla including the subnucleus reticularis dorsalis (SRD) and are mediated by descending pathways in the dorsolateral funiculi. A painful focus that both activates a segmental subset of neurones and inhibits the remaining population can seriously disrupt this basic activity, resulting in the distortion of the body representation in favour of the painful focus, which becomes pre-eminent and (relatively) oversized.
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Andrew D, Matthews B. Displacement of the contents of dentinal tubules and sensory transduction in intradental nerves of the cat. J Physiol 2000; 529 Pt 3:791-802. [PMID: 11118506 PMCID: PMC2270220 DOI: 10.1111/j.1469-7793.2000.00791.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: 11/29/2022] Open
Abstract
Experiments were performed on anaesthetized cats to test the hypothesis that fluid flow through dentinal tubules is part of the mechanism involved in the transduction of pain-producing stimuli in teeth. In 11 animals, fluid flow through dentine and single- and multi-unit activity in intradental nerves were recorded simultaneously during the application of changes in hydrostatic pressure (-500 to +500 mm Hg) to exposed dentine. Seventeen A-fibres (conduction velocity (CV), 10.6-55.1 m s(-1)) were isolated that were pressure sensitive. The thresholds of these units in terms of dentinal fluid flow were in the range 0.3-2.1 nl s(-1) mm(-2) during outward flow from the pulp and 2.0-3.5 nl s(-1) mm(-2) during inward flow. All the units were more sensitive to outward than inward flow. Twenty-eight units (CV, 0.6-48.8 m s-1) were not pressure sensitive, and 12 of these had conduction velocities in the C-fibre range (< 2.5 m s(-1)). The velocities of the tubular contents were calculated by estimating the number and diameters of dentinal tubules exposed. At the threshold of single-fibre responses these velocities were in the range 31.7-222.9 microm s(-1) during outward flow 211.4-369.6 microm s-1 during inward flow. Repetitive pressure stimulation of dentine resulted in a progressive reduction in the evoked discharge, which was probably due to pulp damage. In seven animals, 10 single intradental nerve fibres were selected that responded to hydrostatic pressure stimuli and their responses to the application of hot, cold, osmotic, mechanical and drying stimuli to exposed dentine were investigated. With these stimuli dentinal fluid flow could not be recorded in vivo for technical reasons and was therefore recorded in vitro after completion of the electrophysiological recordings. With each form of stimulus, the discharge evoked in vivo was closely related to the flow predicted from the in vitro measurements. The results were therefore consistent with the hypothesis that the stimuli act through a common transduction mechanism that involves fluid flow through dentine.
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Affiliation(s)
- D Andrew
- Department of Physiology, University of Bristol, Bristol BS8 1TD, UK
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Matthews B, Vongsavan N. Interactions between neural and hydrodynamic mechanisms in dentine and pulp. Arch Oral Biol 1994; 39 Suppl:87S-95S. [PMID: 7702472 DOI: 10.1016/0003-9969(94)90193-7] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Evidence is presented that the rate of inward diffusion of chemicals through exposed dentine is affected by the rate of outward flow of fluid through the dentinal tubules. Such a flow has been demonstrated in cats. The flow rate appears to depend upon the pulpal tissue-fluid pressure; flow increased during pulp vasodilatation and decreased, even reversing in direction, during vasoconstriction. Pulp vasodilatation can be produced by stimulating intradental afferent nerves, including some of those that seem to be excited by displacement of tubule contents (i.e. by a hydrodynamic mechanism). Thus, when dentine is exposed and these afferents are stimulated they will help to protect the pulp by producing reflex vasodilatation, which will decrease the rate of diffusion of toxins from the mouth into the pulp. The relation between the rate of flow through dentine and the discharge evoked in intradental nerves was investigated in cats. Single fibres were more sensitive to outward than to inward flow. The flow rates required to excite the pulp afferents were greater than those observed during even maximal pulpal vasodilatation.
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Affiliation(s)
- B Matthews
- Department of Physiology, School of Medical Sciences, University of Bristol, England
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Boissonade FM, Banks D, Matthews B. Methods for recording the jaw-opening reflex to tooth-pulp stimulation in awake cats. J Neurosci Methods 1991; 38:35-40. [PMID: 1921466 DOI: 10.1016/0165-0270(91)90151-o] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Techniques are described for use in awake, unrestrained cats which enable recordings to be made from the digastric muscle, electrical stimuli to be applied to the teeth, and intravenous injections to be made via an indwelling cannula. A headpiece was fixed to the skull of the animal and leads were passed subcutaneously from it to electrodes in the muscle and the teeth. A silicone rubber cannula was inserted into the external jugular vein and connected to an injection port in the headpiece. The headpiece incorporated a miniature 9-way connector which was connected to the electrode leads.
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Affiliation(s)
- F M Boissonade
- Department of Physiology, School of Medical Science, University Walk, Bristol, U.K
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Takemura M, Sugimoto T, Shigenaga Y. Difference in central projection of primary afferents innervating facial and intraoral structures in the rat. Exp Neurol 1991; 111:324-31. [PMID: 1705521 DOI: 10.1016/0014-4886(91)90099-x] [Citation(s) in RCA: 130] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Transganglionic transport of horseradish peroxidase-wheat germ agglutinin conjugate was used to study the central projection of primary afferent neurons innervating facial and intraoral structures. The examined primary neurons innervating the facial structures were those comprising the frontal and zygomaticofacial nerves and those innervating the cornea, while the primary neurons innervating the intraoral structures included those innervating the mandibular incisor and molar tooth pulps and those comprising the palatine nerve. The primary afferents innervating the facial structures project to the lateral or ventral parts of the trigeminal principal, oral and interpolar subnuclei, and to the rostral cervical spinal dorsal horn across laminae I through V, with a greater proportion being directed to the spinal dorsal horn. The primary afferents innervating the intraoral structures terminate in the dorsomedial subdivisions of the trigeminal principal, oral and interpolar subnuclei, and in laminae I, II, and V of the medial medullary dorsal horn, with a much denser projection being distributed to the rostral subnuclei. In addition to the above brain stem trigeminal sensory nuclear complex, they project to the supratrigeminal nucleus, caudal solitary tract nucleus, and paratrigeminal nucleus. These observations agree with previously reported data that the central projection of trigeminal nerve is organized in different manners for the facial and intraoral structures. Furthermore, the present findings in conjunction with our previous studies clarify that the central projection of primary afferents from the facial skin is organized in a clear somatotopic fashion and that the terminal fields of primary afferents from the intraoral structures extensively overlap in the brain stem trigeminal nuclear complex particularly in its rostral subdivisions. The central mechanism of trigeminal nociception is discussed with particular respect to its difference between the facial and intraoral structures.
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Affiliation(s)
- M Takemura
- Second Department of Oral Anatomy, Osaka University Faculty of Dentistry, Japan
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Matthews MA, Hernandez TV, Romanska AI, Hoffman KD. Golgi and immunocytochemical analysis of neurons in trigeminal subnucleus interpolaris: correlations with cellular localization of enkephalin. Neuroscience 1989; 32:463-80. [PMID: 2479885 DOI: 10.1016/0306-4522(89)90094-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Recent electrophysiological evidence shows that rostral levels of the trigeminal spinal complex are concerned with pain processing from receptive fields in the face and oral cavity. The ventrolateral quadrant of the subnucleus interpolaris contains concentrations of enkephalin, dynorphin, serotonin, substance P and GABA [Matthews M. A., Hernandez T. V. and Liles S. L. (1987) Synapse 1, 512-529; Matthews M. A., McDonald G. K. and Hernandez T. V. (1988) Somatosensory Res. 5, 205-217]. These transmitters have also been localized to the fusiform and stalked cells in Laminae I and II of the subnucleus caudalis [Basbaum A. I. and Fields H. L. (1984) A. Rev. Neurosci. 7, 309-338]. The present study compares Golgi impregnations of the subnucleus interpolaris with sections at the same levels immunoreacted against enkephalin to determine if comparable cells exist in the subnucleus interpolaris and if they occur predominantly in the ventrolateral quadrant of the subnucleus. Twelve, young adult cats were killed by perfusion, the brainstems removed and either processed for rapid Golgi impregnation or sectioned and immunoreacted for enkephalin using the avidin-biotin Vectastain method. Golgi impregnated tissue was sectioned in the coronal, transverse or sagittal plane to insure the most advantageous visualization of cells with a directional bias in their dendritic arbors. The subnucleus interpolaris contained several distinctive cell types. The predominant neuron throughout the subnucleus was the smooth pyramidal cell or multipolar cell, characterized by a large round soma (15-25 microns diameter) and a spherical dendritic arborization which allowed its identification in all planes of section. The second cell type was the fusiform cell which had a smaller ovoid soma (10-15 microns) with narrow, less ramified, dendritic arbors oriented dorsoventrally, thus giving a bipolar appearance. Fusiform cells were most concentrated along the lateral margin of the subnucleus interpolaris. Examination of sections at the same level reacted for enkephalin revealed cells with a bipolar appearance in these same locations. An additional cell population which tended to predominate in the lateral zone was the stalked cell. These displayed a rounded soma (12-20 microns) and were evident only in the transverse or sagittal plane. Two to four primary dendrites arose from the soma and extensively ramified into a dense spiny arbor directed into the body of the subnucleus interpolaris. Many examples contained enkephalin. Islet cells, characterized by a very small oval soma (6-12 microns) and dense, rostrocaudally oriented dendrites, were less common than stalked cells and were located deeper in the nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- M A Matthews
- Department of Anatomy, Louisiana State University Medical Center, New Orleans 70119
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Tinsley PW, Fridland GH, Killmar JT, Desiderio DM. Purification, characterization, and localization of neuropeptides in the cornea. Peptides 1988; 9:1373-9. [PMID: 2470068 DOI: 10.1016/0196-9781(88)90205-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The immunologically detected neuropeptides methionine enkephalin (ME), substance P (SP), beta-endorphin (beta-End), and alpha-melanocyte stimulating hormone (alpha-MSH) were purified from bovine corneal extracts by gradient, followed by isocratic, reversed phase-high performance liquid chromatography (RP-HPLC) and characterized, after both chromatographic steps, by radioimmunoassay (RIA). Immunologically detected ME and SP were purified from canine corneal extracts by gradient RP-HPLC and characterized by RIA. An anatomical study of the bovine cornea separated the cornea into an epithelium-enriched and a stroma-enriched portion. After gradient RP-HPLC, RIA demonstrated that all the ME-like immunoreactivity was located in the corneal epithelium, whereas the SP-like immunoreactivity was distributed between the stroma and epithelium in an approximate two-to-one ratio.
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Affiliation(s)
- P W Tinsley
- Charles B. Stout Neuroscience Mass Spectrometry Laboratory, University of Tennessee, Memphis 38163
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18
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Bereiter DA, Gann DS. Glutamate activation of neurons within trigeminal nucleus caudalis increases adrenocorticotropin in the cat. Pain 1988; 33:341-348. [PMID: 2901707 DOI: 10.1016/0304-3959(88)90294-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The role of trigeminal nucleus caudalis (Vc) in control of the autonomic and endocrine correlates of nociception was assessed in chloralose-anesthetized cats. Microinjections of the neuroexcitatory agent, L-glutamate (0.5 M), were directed at the marginal layers, at the central magnocellular portion, and at the deep magnocellular portion of Vc. Changes in the plasma concentration of adrenocorticotropin (ACTH), in mean arterial pressure, and in heart rate were examined. Glutamate excitation of neurons within the marginal layers of Vc evoked a significant (+143 +/- 52 pg/ml, P less than 0.01) increase in plasma ACTH during the 10 min postinjection sampling period. Glutamate injections into the deep magnocellular portion of Vc also increased plasma ACTH (+97 +/- 28 pg/ml, P less than 0.05), whereas activation of neurons in the central magnocellular portion of Vc had no consistent effect on plasma ACTH (-25 +/- 29 pg/ml, P greater than 0.10). Arterial pressure increased transiently after glutamate injections into the marginal layers or central magnocellular portion of Vc, whereas injections into the deep magnocellular portion of Vc did not affect arterial pressure. Heart rate increased transiently regardless of the laminar site of injection within Vc. These data indicate that activation of neurons in laminar regions of Vc that process nociceptive information cause an increase in plasma ACTH, whereas activation of neurons in laminae of Vc that process mainly non-nociceptive input have no significant influence on plasma ACTH.
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Affiliation(s)
- David A Bereiter
- Departments of Surgery and Neurobiology, Brown University /Rhode Island Hospital, Providence, RI 02902 U.S.A
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Matthews B, Hughes SH. The ultrastructure and receptor transduction mechanisms of dentine. PROGRESS IN BRAIN RESEARCH 1988; 74:69-76. [PMID: 3187045 DOI: 10.1016/s0079-6123(08)63000-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Holland GR, Matthews B, Robinson PP. An electrophysiological and morphological study of the innervation and reinnervation of cat dentine. J Physiol 1987; 386:31-43. [PMID: 3681712 PMCID: PMC1192448 DOI: 10.1113/jphysiol.1987.sp016520] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
1. Experiments were carried out to determine which, if any, of the cellular processes in cat dentine are nerves. This was done by examining in the electron microscope the contents of the dentinal tubules in control teeth and in teeth that had been denervated 56 h previously. The extent of any reinnervation, and associated return of neural responses to dentine stimulation were investigated 12 weeks after denervation. 2. In five cats, the inferior alveolar nerve was sectioned on one side and the cut ends reapposed. 3. Each of the tubules in the predentine of control teeth contained one process with a cross-sectional area of 0.21-1.14 micron2 and up to eight other, secondary processes which were generally smaller. The proportion which contained secondary processes was highest (83%) near the tip of the pulp and decreased further down the side of the crown of the tooth. 4. 56 h after denervation, almost all the secondary processes had disappeared, leaving just one of the larger processes in each tubule. It is concluded that these larger processes are odontoblast processes and that all the secondary processes are nerve terminals. 5. 12 weeks after denervation, small processes were again present in some tubules. Recordings in three cats showed that inferior alveolar nerve fibres had regenerated into the canine pulp and that some of these had re-established receptor properties similar to those in normal teeth.
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Affiliation(s)
- G R Holland
- Faculty of Dentistry, University of Alberta, Edmonton, Canada
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Foong FW, Duggan AW. Brain-stem areas tonically inhibiting dorsal horn neurones: studies with microinjection of the GABA analogue piperidine-4-sulphonic acid. Pain 1986; 27:361-371. [PMID: 3808742 DOI: 10.1016/0304-3959(86)90160-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
In barbiturate anaesthetized cats, tonic inhibition of the excitation of lumbar dorsal horn neurones by impulses in unmyelinated primary afferents was measured by reversibly cooling the spinal cord at the thoraco-lumbar junction. Tonic inhibition was reduced by microinjection of the GABA analogue, piperidine-4-sulphonic acid (2.5 nM in 0.5 microliter) mainly at AP -7, L 2-5 and V -8 to -10. This area in the ventrolateral medulla is just ventral to the facial nucleus and has been shown to be important in cardiovascular control, particularly in relation to fear-defence reactions. It is proposed that tonic inhibition of the nociceptive responses of spinal neurones is part of such a reaction in response to the trauma of surgery. Since previous experiments had shown that the ventrolateral medulla was important in spinal inhibition produced by PAG stimulation, these experiments support the proposal that analgesia does not occur in isolation but is part of a complex behavioural response of an animal in a potentially injurious environment.
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Affiliation(s)
- F W Foong
- Department of Pharmacology, John Curtin School of Medical Research, Australian National University, Canberra, ACT 2601 Australia
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