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Thompson KJ, Watson S, Zanato C, Dall'Angelo S, De Nooij JC, Pace‐Bonello B, Shenton FC, Sanger HE, Heinz BA, Broad LM, Grosjean N, McQuillian JR, Dubini M, Pyner S, Greig I, Zanda M, Bleakman D, Banks RW, Bewick GS. The atypical 'hippocampal' glutamate receptor coupled to phospholipase D that controls stretch-sensitivity in primary mechanosensory nerve endings is homomeric purely metabotropic GluK2. Exp Physiol 2024; 109:81-99. [PMID: 37656490 PMCID: PMC10988755 DOI: 10.1113/ep090761] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 08/08/2023] [Indexed: 09/02/2023]
Abstract
A metabotropic glutamate receptor coupled to phospholipase D (PLD-mGluR) was discovered in the hippocampus over three decades ago. Its pharmacology and direct linkage to PLD activation are well established and indicate it is a highly atypical glutamate receptor. A receptor with the same pharmacology is present in spindle primary sensory terminals where its blockade can totally abolish, and its activation can double, the normal stretch-evoked firing. We report here the first identification of this PLD-mGluR protein, by capitalizing on its expression in primary mechanosensory terminals, developing an enriched source, pharmacological profiling to identify an optimal ligand, and then functionalizing it as a molecular tool. Evidence from immunofluorescence, western and far-western blotting indicates PLD-mGluR is homomeric GluK2, since GluK2 is the only glutamate receptor protein/receptor subunit present in spindle mechanosensory terminals. Its expression was also found in the lanceolate palisade ending of hair follicle, also known to contain the PLD-mGluR. Finally, in a mouse model with ionotropic function ablated in the GluK2 subunit, spindle glutamatergic responses were still present, confirming it acts purely metabotropically. We conclude the PLD-mGluR is a homomeric GluK2 kainate receptor signalling purely metabotropically and it is common to other, perhaps all, primary mechanosensory endings.
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Affiliation(s)
- Karen J. Thompson
- Institute of Medical Sciences, School of Medicine, Medical Sciences & NutritionUniversity of AberdeenAberdeenUK
| | - Sonia Watson
- Institute of Medical Sciences, School of Medicine, Medical Sciences & NutritionUniversity of AberdeenAberdeenUK
| | - Chiara Zanato
- Institute of Medical Sciences, School of Medicine, Medical Sciences & NutritionUniversity of AberdeenAberdeenUK
| | - Sergio Dall'Angelo
- Institute of Medical Sciences, School of Medicine, Medical Sciences & NutritionUniversity of AberdeenAberdeenUK
| | | | | | | | | | | | | | - Noelle Grosjean
- CNRS UMR 5297, Interdisciplinary Institute of NeuroscienceUniversity of BordeauxBordeauxFrance
| | - Jessica R. McQuillian
- Institute of Medical Sciences, School of Medicine, Medical Sciences & NutritionUniversity of AberdeenAberdeenUK
| | - Marina Dubini
- Institute of Medical Sciences, School of Medicine, Medical Sciences & NutritionUniversity of AberdeenAberdeenUK
| | - Susan Pyner
- Department of BiosciencesDurham UniversityDurhamUK
| | - Iain Greig
- Institute of Medical Sciences, School of Medicine, Medical Sciences & NutritionUniversity of AberdeenAberdeenUK
| | - Matteo Zanda
- Institute of Medical Sciences, School of Medicine, Medical Sciences & NutritionUniversity of AberdeenAberdeenUK
| | | | | | - Guy S. Bewick
- Institute of Medical Sciences, School of Medicine, Medical Sciences & NutritionUniversity of AberdeenAberdeenUK
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Kröger S. Experimental Physiology special issue: 'Mechanotransduction, muscle spindles and proprioception'. Exp Physiol 2024; 109:1-5. [PMID: 38160398 PMCID: PMC10988673 DOI: 10.1113/ep091431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 12/13/2023] [Indexed: 01/03/2024]
Affiliation(s)
- Stephan Kröger
- Department of Physiological Genomics, Biomedical CenterLudwig‐Maximilians‐UniversitätPlanegg‐MartinsriedGermany
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García-Mesa Y, García-Piqueras J, Cuendias P, Cobo R, Martín-Cruces J, Feito J, García-Suarez O, Biedma BM, Vega J. SYNAPTOPHYSIN IS A SELECTIVE MARKER FOR AXONS IN HUMAN CUTANEOUS END ORGAN COMPLEXES. Ann Anat 2022; 243:151955. [DOI: 10.1016/j.aanat.2022.151955] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/04/2022] [Accepted: 04/24/2022] [Indexed: 12/25/2022]
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Suazo I, Vega JA, García-Mesa Y, García-Piqueras J, García-Suárez O, Cobo T. The Lamellar Cells of Vertebrate Meissner and Pacinian Corpuscles: Development, Characterization, and Functions. Front Neurosci 2022; 16:790130. [PMID: 35356056 PMCID: PMC8959428 DOI: 10.3389/fnins.2022.790130] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 01/21/2022] [Indexed: 12/15/2022] Open
Abstract
Sensory corpuscles, or cutaneous end-organ complexes, are complex structures localized at the periphery of Aβ-axon terminals from primary sensory neurons that primarily work as low-threshold mechanoreceptors. Structurally, they consist, in addition to the axons, of non-myelinating Schwann-like cells (terminal glial cells) and endoneurial- and perineurial-related cells. The terminal glial cells are the so-called lamellar cells in Meissner and Pacinian corpuscles. Lamellar cells are variably arranged in sensory corpuscles as a “coin stack” in the Meissner corpuscles or as an “onion bulb” in the Pacinian ones. Nevertheless, the origin and protein profile of the lamellar cells in both morphotypes of sensory corpuscles is quite similar, although it differs in the expression of mechano-gated ion channels as well as in the composition of the extracellular matrix between the cells. The lamellar cells have been regarded as supportive cells playing a passive role in the process of genesis of the action potential, i.e., the mechanotransduction process. However, they express ion channels related to the mechano–electric transduction and show a synapse-like mechanism that suggest neurotransmission at the genesis of the electrical action potential. This review updates the current knowledge about the embryonic origin, development modifications, spatial arrangement, ultrastructural characteristics, and protein profile of the lamellar cells of cutaneous end-organ complexes focusing on Meissner and Pacinian morphotypes.
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Affiliation(s)
- Iván Suazo
- Grupo SINPOS, Departamento de Morfología y Biología Celular, Universidad de Oviedo, Oviedo, Spain
- Faculcultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - José A. Vega
- Grupo SINPOS, Departamento de Morfología y Biología Celular, Universidad de Oviedo, Oviedo, Spain
- Faculcultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
- *Correspondence: José A. Vega,
| | - Yolanda García-Mesa
- Grupo SINPOS, Departamento de Morfología y Biología Celular, Universidad de Oviedo, Oviedo, Spain
| | - Jorge García-Piqueras
- Grupo SINPOS, Departamento de Morfología y Biología Celular, Universidad de Oviedo, Oviedo, Spain
| | - Olivia García-Suárez
- Grupo SINPOS, Departamento de Morfología y Biología Celular, Universidad de Oviedo, Oviedo, Spain
| | - Teresa Cobo
- Departamento de Cirugía y Especialidades Médico-Quirúrgicas, Universidad de Oviedo, Oviedo, Spain
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Barrett P, Quick TJ, Mudera V, Player DJ. Generating intrafusal skeletal muscle fibres in vitro: Current state of the art and future challenges. J Tissue Eng 2020; 11:2041731420985205. [PMID: 34956586 PMCID: PMC8693220 DOI: 10.1177/2041731420985205] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 12/12/2020] [Indexed: 01/18/2023] Open
Abstract
Intrafusal fibres are a specialised cell population in skeletal muscle, found within the muscle spindle. These fibres have a mechano-sensory capacity, forming part of the monosynaptic stretch-reflex arc, a key component responsible for proprioceptive function. Impairment of proprioception and associated dysfunction of the muscle spindle is linked with many neuromuscular diseases. Research to-date has largely been undertaken in vivo or using ex vivo preparations. These studies have provided a foundation for our understanding of muscle spindle physiology, however, the cellular and molecular mechanisms which underpin physiological changes are yet to be fully elucidated. Therefrom, the use of in vitro models has been proposed, whereby intrafusal fibres can be generated de novo. Although there has been progress, it is predominantly a developing and evolving area of research. This narrative review presents the current state of art in this area and proposes the direction of future work, with the aim of providing novel pre-clinical and clinical applications.
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Affiliation(s)
- Philip Barrett
- Centre for 3D Models of Health and Disease, Division of Surgery and Interventional Science, Faculty of Medical Sciences, University College London, London, UK
| | - Tom J Quick
- Peripheral Nerve Injury Research Unit, Royal National Orthopaedic Hospital, Stanmore, UK
- UCL Centre for Nerve Engineering, University College London, London, UK
| | - Vivek Mudera
- Centre for 3D Models of Health and Disease, Division of Surgery and Interventional Science, Faculty of Medical Sciences, University College London, London, UK
| | - Darren J Player
- Centre for 3D Models of Health and Disease, Division of Surgery and Interventional Science, Faculty of Medical Sciences, University College London, London, UK
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6
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Brognara F, Felippe ISA, Salgado HC, Paton JFR. Autonomic innervation of the carotid body as a determinant of its sensitivity: implications for cardiovascular physiology and pathology. Cardiovasc Res 2020; 117:1015-1032. [PMID: 32832979 DOI: 10.1093/cvr/cvaa250] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 07/01/2020] [Accepted: 08/18/2020] [Indexed: 12/14/2022] Open
Abstract
The motivation for this review comes from the emerging complexity of the autonomic innervation of the carotid body (CB) and its putative role in regulating chemoreceptor sensitivity. With the carotid bodies as a potential therapeutic target for numerous cardiorespiratory and metabolic diseases, an understanding of the neural control of its circulation is most relevant. Since nerve fibres track blood vessels and receive autonomic innervation, we initiate our review by describing the origins of arterial feed to the CB and its unique vascular architecture and blood flow. Arterial feed(s) vary amongst species and, unequivocally, the arterial blood supply is relatively high to this organ. The vasculature appears to form separate circuits inside the CB with one having arterial venous anastomoses. Both sympathetic and parasympathetic nerves are present with postganglionic neurons located within the CB or close to it in the form of paraganglia. Their role in arterial vascular resistance control is described as is how CB blood flow relates to carotid sinus afferent activity. We discuss non-vascular targets of autonomic nerves, their possible role in controlling glomus cell activity, and how certain transmitters may relate to function. We propose that the autonomic nerves sub-serving the CB provide a rapid mechanism to tune the gain of peripheral chemoreflex sensitivity based on alterations in blood flow and oxygen delivery, and might provide future therapeutic targets. However, there remain a number of unknowns regarding these mechanisms that require further research that is discussed.
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Affiliation(s)
- Fernanda Brognara
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton Auckland 1023, New Zealand.,Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Igor S A Felippe
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton Auckland 1023, New Zealand
| | - Helio C Salgado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Julian F R Paton
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, 85 Park Road, Grafton Auckland 1023, New Zealand
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On the existence of mechanoreceptors within the neurovascular unit of the mammalian brain. Brain Struct Funct 2019; 224:2247-2267. [PMID: 31190162 DOI: 10.1007/s00429-019-01863-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 03/16/2019] [Indexed: 10/26/2022]
Abstract
We describe a set of perivascular interneurons (PINs) with series of fibro-vesicular complexes (FVCs) throughout the gray matter of the adult rabbit and rat brains. PIN-FVCs are ubiquitous throughout the brain vasculature as detected in Golgi-impregnated specimens. Most PINs are small, aspiny cells with short or long (> 1 mm) axons that split and travel along arterial blood vessels. Upon ramification, axons form FVCs around the arising vascular branches; then, paired axons run parallel to the vessel wall until another ramification ensues, and a new FVC is formed. Cytologically, FVCs consist of clusters of perivascular bulbs (PVBs) encircling the precapillary and capillary wall surrounded by end-feet and the extracellular matrix of endothelial cells and pericytes. A PVB contains mitochondria, multivesicular bodies, and granules with a membranous core, similar to Meissner corpuscles and other mechanoreceptors. Some PVBs form asymmetrical, axo-spinous synapses with presumptive adjacent neurons. PINs appear to correspond to the type 1 nNOS-positive neurons whose FVCs co-label with markers of sensory fiber-terminals surrounded by astrocytic end-feet. The PIN is conserved in adult cats and rhesus monkey specimens. The location, ubiquity throughout the vasculature of the mammalian brain, and cytological organization of the PIN-FVCs suggests that it is a sensory receptor intrinsic to the mammalian neurovascular unit that corresponds to an afferent limb of the sensorimotor feed-back mechanism controlling local blood flow.
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Gerwin L, Haupt C, Wilkinson KA, Kröger S. Acetylcholine receptors in the equatorial region of intrafusal muscle fibres modulate mouse muscle spindle sensitivity. J Physiol 2019; 597:1993-2006. [PMID: 30673133 DOI: 10.1113/jp277139] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 01/22/2019] [Indexed: 01/08/2023] Open
Abstract
KEY POINTS Acetylcholine receptors are aggregated in the central regions of intrafusal muscle fibres. Single unit muscle spindle afferent responses from isolated mouse extensor digitorum longus muscle were recorded in the absence of fusimotor input to ramp and hold stretches as well as to sinusoidal vibrations in the presence and absence of the acetylcholine receptor blockers d-tubocurarine and α-bungarotoxin. Proprioceptive afferent responses to both types of stretch were enhanced in the presence of either blocker. Blocking acetylcholine uptake and vesicular acetylcholine release by hemicholinium-3 also enhanced stretch-evoked responses. These results represent the first evidence that acetylcholine receptors negatively modulate muscle spindle responses to stretch. The data support the hypothesis that the sensory nerve terminal is able to release vesicles to fine-tune proprioceptive afferent sensitivity. ABSTRACT Muscle spindles are complex stretch-sensitive mechanoreceptors. They consist of specialized skeletal muscle fibres, called intrafusal fibres, which are innervated in the central (equatorial) region by afferent sensory axons and in both polar regions by efferent γ-motoneurons. Previously it was shown that acetylcholine receptors (AChR) are concentrated in the equatorial region at the contact site between the sensory neuron and the intrafusal muscle fibre. To address the function of these AChRs, single unit sensory afferents were recorded from an isolated mouse extensor digitorum longus muscle in the absence of γ-motoneuron activity. Specifically, we investigated the responses of individual sensory neurons to ramp-and-hold stretches and sinusoidal vibrations before and after the addition of the competitive and non-competitive AChR blockers d-tubocurarine and α-bungarotoxin, respectively. The presence of either drug did not affect the resting action potential discharge frequency. However, the action potential frequencies in response to stretch were increased. In particular, frequencies of the dynamic peak and dynamic index to ramp-and-hold stretches were significantly higher in the presence of either drug. Treatment of muscle spindle afferents with the high-affinity choline transporter antagonist hemicholinium-3 similarly increased muscle spindle afferent firing frequencies during stretch. Moreover, the firing rate during sinusoidal vibration stimuli at low amplitudes was higher in the presence of α-bungarotoxin compared to control spindles also indicating an increased sensitivity to stretch. Collectively these data suggest a modulation of the muscle spindle afferent response to stretch by AChRs in the central region of intrafusal fibres possibly fine-tuning muscle spindle sensitivity.
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Affiliation(s)
- Laura Gerwin
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Großhaderner Str. 9, D-82152, Planegg-Martinsried, Germany.,Institute for Stem Cell Research, German Research Center for Environmental Health, Helmholtz Centre Munich, Ingolstädter Landstraße 1, D-85764, Neuherberg, Germany
| | - Corinna Haupt
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Großhaderner Str. 9, D-82152, Planegg-Martinsried, Germany
| | - Katherine A Wilkinson
- Department of Biological Sciences, San Jose State University, One Washington Square, San Jose, CA, 95192, USA
| | - Stephan Kröger
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Großhaderner Str. 9, D-82152, Planegg-Martinsried, Germany
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Tu H, Zhang D, Li YL. Cellular and Molecular Mechanisms Underlying Arterial Baroreceptor Remodeling in Cardiovascular Diseases and Diabetes. Neurosci Bull 2018; 35:98-112. [PMID: 30146675 DOI: 10.1007/s12264-018-0274-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 05/31/2018] [Indexed: 01/23/2023] Open
Abstract
Clinical trials and animal experimental studies have demonstrated an association of arterial baroreflex impairment with the prognosis and mortality of cardiovascular diseases and diabetes. As a primary part of the arterial baroreflex arc, the pressure sensitivity of arterial baroreceptors is blunted and involved in arterial baroreflex dysfunction in cardiovascular diseases and diabetes. Changes in the arterial vascular walls, mechanosensitive ion channels, and voltage-gated ion channels contribute to the attenuation of arterial baroreceptor sensitivity. Some endogenous substances (such as angiotensin II and superoxide anion) can modulate these morphological and functional alterations through intracellular signaling pathways in impaired arterial baroreceptors. Arterial baroreceptors can be considered as a potential therapeutic target to improve the prognosis of patients with cardiovascular diseases and diabetes.
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Affiliation(s)
- Huiyin Tu
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Dongze Zhang
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA
| | - Yu-Long Li
- Department of Emergency Medicine, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
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