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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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Yamamoto Y, Sasaki K, Komuro M, Yokoyama T, Abdali SS, Nakamuta N. Three-dimensional architecture of the subepithelial corpuscular nerve ending in the rat epiglottis reconstructed by array tomography with scanning electron microscopy. J Comp Neurol 2023; 531:1846-1866. [PMID: 37794741 DOI: 10.1002/cne.25544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 07/14/2023] [Accepted: 09/14/2023] [Indexed: 10/06/2023]
Abstract
In the rat laryngeal mucosa, subepithelial corpuscular nerve endings, called laminar nerve endings, are distributed in the epiglottis and arytenoid region and are activated by the pressure changes of the laryngeal cavity. They are also suggested to play a role in efferent regulation because of secretory vesicles in the axoplasm. In the present study, the laminar nerve endings in the rat laryngeal mucosa were analyzed by 3D reconstruction from serial ultrathin sections in addition to immunohistochemistry for synapsin 1. In the light microscopy, synapsin 1-immunoreactive flattened or bulbous terminal parts of the laminar endings were also immunoreactive with VGLUT1, and were surrounded by S100- or S100B-immunoreactive Schwann cells and vimentin-immunoreactive fibroblasts. In the electron microscopy, 3D reconstruction views showed that laminar endings were composed of flattened terminal parts sized 2-5 μm in longitudinal length, overlapping in three to five multiple layers. The terminal parts of the endings were incompletely wrapped by flat cytoplasmic processes of the Schwann cells. In addition, the fibroblast network surrounded the complex of nerve endings and the Schwann cells. Several terminal parts entered through the basement membrane into the epithelial layer and attached to the basal epithelial cells, suggesting that interaction between epithelial cells and laminar nerve endings plays an important role in sensing the pressure changes in the laryngeal cavity. Secretory vesicles were unevenly distributed throughout the terminal part of the laminar nerve endings. The secretory vesicles were frequently observed in the peripheral limb of the terminal parts. It suggests that the laminar nerve endings in the larynx may release glutamate to maintain continuous discharge during the stretching of the laryngeal mucosa.
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Affiliation(s)
- Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Kuniaki Sasaki
- Center for Electron Microscopy, Iwate University, Morioka, Japan
| | - Misaki Komuro
- Center for Electron Microscopy, Iwate University, Morioka, Japan
| | - Takuya Yokoyama
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Sayed Sharif Abdali
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Nobuaki Nakamuta
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
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Moriai H, Yokoyama T, Abdali SS, Nakamuta N, Yamamoto Y. Distribution of proteins for synaptic release in nerve endings associated with the trachealis muscle of rats. Auton Neurosci 2023; 244:103042. [PMID: 36370593 DOI: 10.1016/j.autneu.2022.103042] [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: 07/30/2022] [Revised: 10/08/2022] [Accepted: 11/03/2022] [Indexed: 11/09/2022]
Abstract
The immunohistochemical localization of proteins for synaptic release was examined in smooth muscle-associated sensory nerve endings using whole-mount preparations of the rat trachea. Plant-like smooth muscle-associated nerve endings with immunoreactivity for Na+-K+-ATPase, α3-subunit were identified in the trachealis muscle. VGLUT1, synapsin1, t-SNARE proteins (SNAP25 and syntaxin1), v-SNARE proteins (VAMP1 and VAMP2), and a presynaptic active zone-related protein (piccolo) were detected in the terminal parts of these endings. These results suggest that smooth muscle-associated nerve endings secrete glutamate to modulate sensorimotor functions in the lung deflation reflex.
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Affiliation(s)
- Hisae Moriai
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Takuya Yokoyama
- Department of Anatomy (Cell Biology), Iwate Medical University, Yahaba, Japan
| | - Sayed Sharif Abdali
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Nobuaki Nakamuta
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan
| | - Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Japan.
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Cahusac PM, Veermalla A. Effects of camphor and related compounds on slowly adapting mechanoreceptors in the rat sinus hair follicle. IBRO Neurosci Rep 2022; 13:114-119. [PMID: 35899231 PMCID: PMC9310123 DOI: 10.1016/j.ibneur.2022.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/16/2022] [Accepted: 07/16/2022] [Indexed: 12/02/2022] Open
Abstract
Introduction Camphor is a popular compound for therapeutic and cosmetic use with a distinctive odour, and somatosensory warming and cooling properties. The mechanisms for its action remain unclear. Objective The current study examined the effects of two enantiomers of camphor and related monoterpenoid compounds on mechanoreceptors. Methods Extracellular recordings were made in an in vitro bath preparation. Camphor, borneol, eugenol, carveol, and thymol were tested on the neural activity of St I and St II slowly adapting mechanoreceptors in the rat vibrissal hair follicle preparation. Results All compounds tested (0.5 – 2 mM bath concentrations) resulted in dose-dependent depression of spontaneous and mechanically evoked firing (dynamic and static phases). The mean latency of responses also increased. Both St I and St II were similarly affected, although (-)-camphor had a greater depressant effect on St II than on St I units. Differences were found across the different compounds for their effect on the dynamic and static phases. Thymol was found to have the greatest depressant effect on these phases. The broad spectrum TRP blocker ruthenium red did not reverse the depressant effects of camphor. The depressant effects of the compounds appeared similar to those obtained using the local anaesthetic lignocaine. The depressant effects of camphor and of lignocaine were partially reversed by the K+ channel blocker tetraethylammonium. Conclusions The results question whether the depressant effects of camphor and related compounds act through TRP channels. Perhaps the use of more selective blockers may reveal the molecular mechanisms through which these compounds act.
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Sonekatsu M, Yamada H, Nishio N, Gu JG. Effects on low threshold mechanoreceptors in whisker hair follicles by 5-HT, Cd 2+, tetraethylammonium, 4-aminopyridine, and Ba 2. Mol Pain 2022; 18:17448069221076606. [PMID: 35189758 PMCID: PMC8873973 DOI: 10.1177/17448069221076606] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Low threshold mechanoreceptors (LTMRs) are important for environmental exploration, social interaction, and tactile discrimination. Whisker hair follicles are mechanical sensory organs in non-primate mammals that are functionally equivalent to human fingertips. Several functional types of LTMRs have been identified in rodent whisker hair follicles, including rapidly adapting (RA), slow adapting type 1 (SA1), and slowly adapting type 2 (SA2) LTMRs. Properties of these LTMRs have not been fully characterized. In the present study, we have used pressure-clamped single-fiber recording technique to record impulses of RA, SA1, and SA2 LTMRs in mouse whisker hair follicles, and tested effects of 5-HT, Cd2+, tetraethylammonium (TEA), 4-aminopyridine (4-AP), and Ba2+ on the LTMR impulses. We show that 5-HT at 2 mM suppresses SA1 impulses but has no effects on RA and SA2 impulses. Cd2+ at 100 μM suppresses both SA1 and SA2 impulses but has no effects on RA impulses. TEA at 10 mM has no effects on RA and SA1 impulses but increased SA2 impulses. However, TEA at 1 mM and 200 μM decreases SA2 impulses. 4-AP at 1 mM suppresses both SA1 and SA2 impulses but has no effects on RA impulses. Ba2+ at 5 mM increases both RA and SA1 impulses but suppresses SA2 impulses. Collectively, RA, SA1, and SA2 LTMRs show distinct pharmacological properties, suggesting that these LTMRs may use different mechanisms to tune their mechanical signaling.
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Affiliation(s)
- Mayumi Sonekatsu
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA.,Department of Orthopaedic Surgery, 13145Wakayama Medical University, Wakayama, Japan
| | - Hiroshi Yamada
- Department of Orthopaedic Surgery, 13145Wakayama Medical University, Wakayama, Japan
| | - Naoko Nishio
- Department of Orthopaedic Surgery, 13145Wakayama Medical University, Wakayama, Japan
| | - Jianguo G Gu
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
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Yamamoto Y, Moriai H, Yokoyama T, Nakamuta N. Immunohistochemical distribution of proteins involved in glutamate release in subepithelial sensory nerve endings of rat epiglottis. Histochem Cell Biol 2021; 157:51-63. [PMID: 34613496 DOI: 10.1007/s00418-021-02038-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2021] [Indexed: 11/25/2022]
Abstract
To elucidate the efferent functions of sensory nerve endings, the distribution of calretinin and vesicular glutamate transporter 1 (VGLUT1) in laryngeal laminar nerve endings and the immunohistochemical distribution of proteins associated with synaptic vesicle release, i.e., t-SNARE (SNAP25 and syntaxin 1), v-SNARE (VAMP1 and VAMP2), synaptotagmin 1 (Syt1), bassoon, and piccolo, were examined. Subepithelial laminar nerve endings immunoreactive for Na+-K+-ATPase α3-subunit (NKAα3) were largely distributed in the whole-mount preparation of the epiglottic mucosa, and several endings were also immunoreactive for calretinin. VGLUT1 immunoreactivity was observed within terminal part near the outline of the small processes of NKAα3-immunoreactive nerve ending. SNAP25, syntaxin 1, and VAMP1 immunoreactivities were detected in terminal parts of calretinin-immunoreactive endings, whereas VAMP2 immunoreactivity was only observed in a few terminals. Terminal parts immunoreactive for calretinin and/or VGLUT1 also exhibited immunoreactivities for Syt1, Ca2+ sensor for membrane trafficking, and for bassoon and piccolo, presynaptic scaffold proteins. The presence of vesicular release-related proteins, including SNARE proteins, in the terminals of laryngeal laminar endings indicate that intrinsic glutamate modulates their afferent activity in an autocrine-like manner.
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Affiliation(s)
- Yoshio Yamamoto
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, 18-8, Ueda 3-chome, Morioka, Iwate, 020-8550, Japan.
| | - Hisae Moriai
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, 18-8, Ueda 3-chome, Morioka, Iwate, 020-8550, Japan
| | - Takuya Yokoyama
- Department of Anatomy (Cell Biology), Iwate Medical University, 1-1-1 Idaidori, Yahaba, Iwate, 028-3694, Japan
| | - Nobuaki Nakamuta
- Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, 18-8, Ueda 3-chome, Morioka, Iwate, 020-8550, Japan
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Cahusac PMB, Senok SS. Does Hyaluronidase Enhance Drug Penetration to Mechanoreceptors? Skin Pharmacol Physiol 2020; 33:253-260. [PMID: 33053558 DOI: 10.1159/000510890] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 08/11/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND The pharmacological study of mechanoreceptors embedded within tissue is hampered by tissue barriers to applied research drugs. METHODS Hyaluronidase increases the permeability of tissues and is used clinically to facilitate the distribution of injected drugs. An in vitro rat sinus hair preparation was used to determine whether hyaluronidase (1,500 or 3,000 IU/10 mL) had an effect on drug access to receptor sites on slowly adapting St I and St II mechanoreceptors. Electrical recordings were made from single mechanoreceptor units that were activated by trapezoid ramp stimuli. Cinnamaldehyde (500-1,500 μM) and capsazepine (100 μM) were used as test drugs. Changes in onset time and degree of depression of firing due to test drugs were compared to control experiments not employing hyaluronidase. RESULTS There were no statistical effects on any of the observed measures. Often the effects were opposite to those predicted. Using a likelihood approach, it was calculated that there was strong evidence (log-likelihood ratios from -0.5 to -6.5) to support a null effect over a facilitatory effect. There was no evidence of loss of integrity of mechanoreceptor mechanotransduction mechanisms following hyaluronidase applications. Comparison with Existing Method: The use of hyaluronidase does not facilitate drug access to receptors. CONCLUSIONS In the in vitro sinus hair preparation, the addition of hyaluronidase does not allow easier access to slowly adapting mechanoreceptors within the follicle.
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Affiliation(s)
- Peter M B Cahusac
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia, .,Department of Comparative Medicine, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia,
| | - Solomon S Senok
- Ajman University School of Medicine, Ajman, United Arab Emirates
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Hoffman BU, Baba Y, Griffith TN, Mosharov EV, Woo SH, Roybal DD, Karsenty G, Patapoutian A, Sulzer D, Lumpkin EA. Merkel Cells Activate Sensory Neural Pathways through Adrenergic Synapses. Neuron 2018; 100:1401-1413.e6. [PMID: 30415995 DOI: 10.1016/j.neuron.2018.10.034] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 09/21/2018] [Accepted: 10/22/2018] [Indexed: 01/06/2023]
Abstract
Epithelial-neuronal signaling is essential for sensory encoding in touch, itch, and nociception; however, little is known about the release mechanisms and neurotransmitter receptors through which skin cells govern neuronal excitability. Merkel cells are mechanosensory epidermal cells that have long been proposed to activate neuronal afferents through chemical synaptic transmission. We employed a set of classical criteria for chemical neurotransmission as a framework to test this hypothesis. RNA sequencing of adult mouse Merkel cells demonstrated that they express presynaptic molecules and biosynthetic machinery for adrenergic transmission. Moreover, live-cell imaging directly demonstrated that Merkel cells mediate activity- and VMAT-dependent release of fluorescent catecholamine neurotransmitter analogs. Touch-evoked firing in Merkel-cell afferents was inhibited either by pre-synaptic silencing of SNARE-mediated vesicle release from Merkel cells or by neuronal deletion of β2-adrenergic receptors. Together, these results identify both pre- and postsynaptic mechanisms through which Merkel cells excite mechanosensory afferents to encode gentle touch. VIDEO ABSTRACT.
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Affiliation(s)
- Benjamin U Hoffman
- Department of Physiology & Cellular Biophysics, Columbia University, New York, NY, USA; Program in Neurobiology & Behavior, Columbia University, New York, NY, USA
| | - Yoshichika Baba
- Department of Physiology & Cellular Biophysics, Columbia University, New York, NY, USA
| | - Theanne N Griffith
- Department of Physiology & Cellular Biophysics, Columbia University, New York, NY, USA
| | - Eugene V Mosharov
- Departments of Psychiatry, Neurology, and Pharmacology, Columbia University: Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA
| | - Seung-Hyun Woo
- The Scripps Research Institute & Howard Hughes Medical Institute, La Jolla, CA, USA
| | - Daniel D Roybal
- Pharmacology Graduate Program, Columbia University, New York, NY, USA
| | - Gerard Karsenty
- Department of Genetics and Development, Columbia University, New York, NY, USA
| | - Ardem Patapoutian
- The Scripps Research Institute & Howard Hughes Medical Institute, La Jolla, CA, USA
| | - David Sulzer
- Departments of Psychiatry, Neurology, and Pharmacology, Columbia University: Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA
| | - Ellen A Lumpkin
- Department of Physiology & Cellular Biophysics, Columbia University, New York, NY, USA; Program in Neurobiology & Behavior, Columbia University, New York, NY, USA; Department of Dermatology, Columbia University, New York, NY, USA.
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Zhang FX, Ge SN, Dong YL, Shi J, Feng YP, Li Y, Li YQ, Li JL. Vesicular glutamate transporter isoforms: The essential players in the somatosensory systems. Prog Neurobiol 2018; 171:72-89. [PMID: 30273635 DOI: 10.1016/j.pneurobio.2018.09.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 08/28/2018] [Accepted: 09/23/2018] [Indexed: 02/08/2023]
Abstract
In nervous system, glutamate transmission is crucial for centripetal conveyance and cortical perception of sensory signals of different modalities, which necessitates vesicular glutamate transporters 1-3 (VGLUT 1-3), the three homologous membrane-bound protein isoforms, to load glutamate into the presysnaptic vesicles. These VGLUTs, especially VGLUT1 and VGLUT2, selectively label and define functionally distinct neuronal subpopulations at each relay level of the neural hierarchies comprising spinal and trigeminal sensory systems. In this review, by scrutinizing each structure of the organism's fundamental hierarchies including dorsal root/trigeminal ganglia, spinal dorsal horn/trigeminal sensory nuclear complex, somatosensory thalamic nuclei and primary somatosensory cortex, we summarize and characterize in detail within each relay the neuronal clusters expressing distinct VGLUT protein/transcript isoforms, with respect to their regional distribution features (complementary distribution in some structures), axonal terminations/peripheral innervations and physiological functions. Equally important, the distribution pattern and characteristics of VGLUT1/VGLUT2 axon terminals within these structures are also epitomized. Finally, the correlation of a particular VGLUT isoform and its physiological role, disclosed thus far largely via studying the peripheral receptors, is generalized by referring to reports on global and conditioned VGLUT-knockout mice. Also, researches on VGLUTs relating to future direction are tentatively proposed, such as unveiling the elusive differences between distinct VGLUTs in mechanism and/or pharmacokinetics at ionic/molecular level, and developing VGLUT-based pain killers.
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Affiliation(s)
- Fu-Xing Zhang
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Shun-Nan Ge
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China; Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, PR China
| | - Yu-Lin Dong
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Juan Shi
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Yu-Peng Feng
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China
| | - Yang Li
- Department of Neurosurgery, Tangdu Hospital, The Fourth Military Medical University, Xi'an 710038, PR China
| | - Yun-Qing Li
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China; Collaborative Innovation Center for Brain Science, Fudan University, Shanghai 200032, PR China.
| | - Jin-Lian Li
- Department of Anatomy and K.K. Leung Brain Research Centre, School of Basic Medicine, The Fourth Military Medical University, Xi'an 710032, PR China.
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Katselou M, Papoutsis I, Nikolaou P, Misailidi N, Spiliopoulou C, Athanaselis S. Diphenidine: a dissociative NPS makes an entrance on the drug scene. Forensic Toxicol 2018. [DOI: 10.1007/s11419-018-0421-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Signaling by Synaptic Zinc is Required for Whisker-Mediated, Fine Texture Discrimination. Neuroscience 2017; 369:242-247. [PMID: 29158108 DOI: 10.1016/j.neuroscience.2017.11.020] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 11/06/2017] [Accepted: 11/11/2017] [Indexed: 01/08/2023]
Abstract
Zinc-containing terminals are found throughout the neocortex, concentrated predominantly in layers II/III, V, and VI. Synaptic zinc is a potent neurotransmitter/modulator and, therefore, may mediate inter- or intra-cortical integration of sensory information. We have previously shown that levels of synaptic zinc are rapidly modulated in somatosensory (barrel) cortex, in an experience- and activity-dependent manner. Zinc transporter 3 (ZnT3) knockout (KO) mice lack synaptic zinc and provide us with a good model to examine the contribution of synaptic zinc to barrel cortex-dependent behavior. In the present study, we show that ZnT3 KO mice display a marked decrease in acuity for whisker-dependent texture discrimination. ZnT3 KO mice were not able to discriminate between textures having an average particle diameter less than 300 μm while control mice were able to discriminate between textures having particle diameters separated by as little as 25 μm. This loss of texture discrimination acuity in ZnT3 KO mice was whisker-dependent and was observed in young (2 months-of-age) and older mice (12 months-of-age). These results show that zincergic signaling is necessary for the normal integration of somatosensory information.
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12
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Physiological Roles of Non-Neuronal NMDA Receptors. Trends Pharmacol Sci 2016; 37:750-767. [DOI: 10.1016/j.tips.2016.05.012] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/23/2016] [Accepted: 05/27/2016] [Indexed: 12/14/2022]
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Yokoyama T, Nakamuta N, Kusakabe T, Yamamoto Y. Vesicular glutamate transporter 2-immunoreactive afferent nerve terminals in the carotid body of the rat. Cell Tissue Res 2014; 358:271-5. [DOI: 10.1007/s00441-014-1921-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Accepted: 05/15/2014] [Indexed: 01/24/2023]
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14
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Halata Z, Grim M, Baumann KI. Current understanding of Merkel cells, touch reception and the skin. ACTA ACUST UNITED AC 2014. [DOI: 10.1586/edm.09.70] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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15
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Orime M, Ushiki T, Koga D, Ito M. Three-Dimensional Morphology of Touch Domes in Human Hairy Skin by Correlative Light and Scanning Electron Microscopy. J Invest Dermatol 2013; 133:2108-11. [DOI: 10.1038/jid.2013.60] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Maksimovic S, Baba Y, Lumpkin EA. Neurotransmitters and synaptic components in the Merkel cell-neurite complex, a gentle-touch receptor. Ann N Y Acad Sci 2013; 1279:13-21. [PMID: 23530998 DOI: 10.1111/nyas.12057] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Merkel cells are an enigmatic group of rare cells found in the skin of vertebrates. Most make contacts with somatosensory afferents to form Merkel cell-neurite complexes, which are gentle-touch receptors that initiate slowly adapting type I responses. The function of Merkel cells within the complex remains debated despite decades of research. Numerous anatomical studies demonstrate that Merkel cells form synaptic-like contacts with sensory afferent terminals. Moreover, recent molecular analysis reveals that Merkel cells express dozens of presynaptic molecules that are essential for synaptic vesicle release in neurons. Merkel cells also produce a host of neuroactive substances that can act as fast excitatory neurotransmitters or neuromodulators. Here, we review the major neurotransmitters found in Merkel cells and discuss these findings in relation to the potential function of Merkel cells in touch reception.
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Affiliation(s)
- Srdjan Maksimovic
- Department of Dermatology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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Soda Y, Yamamoto Y. Morphology and chemical characteristics of subepithelial laminar nerve endings in the rat epiglottic mucosa. Histochem Cell Biol 2012; 138:25-39. [DOI: 10.1007/s00418-012-0939-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/11/2012] [Indexed: 01/13/2023]
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18
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Abstract
The sense of touch detects forces that bombard the body's surface. In metazoans, an assortment of morphologically and functionally distinct mechanosensory cell types are tuned to selectively respond to diverse mechanical stimuli, such as vibration, stretch, and pressure. A comparative evolutionary approach across mechanosensory cell types and genetically tractable species is beginning to uncover the cellular logic of touch reception.
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Affiliation(s)
- Ellen A Lumpkin
- Department of Dermatology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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19
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Haas HS, Linecker A, Pfragner R, Sadjak A. Peripheral glutamate signaling in head and neck areas. Head Neck 2011; 32:1554-72. [PMID: 20848447 DOI: 10.1002/hed.21438] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The major excitatory neurotransmitter glutamate is also found in the periphery in an increasing number of nonexcitable cells. In line with this it became apparent that glutamate can regulate a broad array of peripheral biological responses, as well. Of particular interest is the discovery that glutamate receptor reactive reagents can influence tumor biology. However, the knowledge of glutamate signaling in peripheral tissues is still incomplete and, in the case of head and neck areas, is almost lacking. The roles of glutamate signaling pathways in these regions are manifold and include orofacial pain, periodontal bone production, skin and airway inflammation, as well as salivation. Furthermore, the interrelations between glutamate and cancers in the oral cavity, thyroid gland, and other regions are discussed. In summary, this review shall strengthen the view that glutamate receptor reagents may also be promising targets for novel therapeutic concepts suitable for a number of diseases in peripheral tissues. The contents of this review cover the following sections: Introduction; The "Glutamate System"; The Taste of Glutamate; Glutamate Signaling in Dental Regions; Glutamate Signaling in Head and Neck Areas; Glutamate Signaling in Head and Neck Cancer; A Brief Overview of Glutamate Signaling in Other Cancers; and Conclusion.
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Affiliation(s)
- Helga Susanne Haas
- Department of Pathophysiology and Immunology, Center of Molecular Medicine, Medical University of Graz, Graz, Austria.
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20
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Press D, Mutlu S, Güçlü B. Evidence of fast serotonin transmission in frog slowly adapting type 1 responses. Somatosens Mot Res 2010; 27:174-85. [PMID: 20937000 DOI: 10.3109/08990220.2010.516670] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Merkel cell-neurite (MCN) complex generates slowly adapting type 1 (SA1) response when mechanically stimulated. Both serotonin (5-HT) and glutamate have been implicated in the generation of normal SA1 responses, but previous studies have been inconclusive as to what their roles are or how synaptic transmission occurs. In this study, excised dorsal skin patches from common water frogs (Rana ridibunda) were stimulated by von Frey hairs during perfusion in a tissue bath, and single-unit spike activity was recorded from SA1 fibres. Serotonin had no significant effect on the SA1 response at low (10 µM) concentration, significantly increased activity in a force-independent manner at 100 µM, but decreased activity with reduced responsiveness to force at 1 mM. Glutamate showed no effect on the responsiveness to force at 100 µM. MDL 72222 (100 µM), an ionotropic 5-HT3 receptor antagonist, completely abolished the responsiveness to force, suggesting that serotonin is released from Merkel cells as a result of mechanical stimulation, and activated 5-HT3 receptors on the neurite. The metabotropic 5-HT2 receptor antagonist, ketanserin, greatly reduced the SA1 fibre's responsiveness to force, as did the non-specific glutamate receptor antagonist, kynurenic acid. This supports a role for serotonin and glutamate as neuromodulators in the MCN complex, possibly by activation and/or inhibition of signalling cascades in the Merkel cell associated with vesicle release. Additionally, it was observed that SA1 responses contained a force-independent component, similar to a dynamic response observed during mechanical vibrations.
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Affiliation(s)
- Daniel Press
- Biomedical Engineering Institute, Boğaziçi University, İstanbul, Turkey
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21
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Petralia RS, Wang YX, Hua F, Yi Z, Zhou A, Ge L, Stephenson FA, Wenthold RJ. Organization of NMDA receptors at extrasynaptic locations. Neuroscience 2010; 167:68-87. [PMID: 20096331 DOI: 10.1016/j.neuroscience.2010.01.022] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 12/14/2009] [Accepted: 01/13/2010] [Indexed: 12/14/2022]
Abstract
NMDA receptors are found in neurons both at synapses and in extrasynaptic locations. Extrasynaptic locations are poorly characterized. Here we used preembedding immunoperoxidase and postembedding immunogold electron microscopy and fluorescence light microscopy to characterize extrasynaptic NMDA receptor locations in dissociated hippocampal neurons in vitro and in the adult and postnatal hippocampus in vivo. We found that extrasynaptic NMDA receptors on neurons in vivo and in vitro were usually concentrated at points of contact with adjacent processes, which were mainly axons, axon terminals, or glia. Many of these contacts were shown to contain adhesion factors such as cadherin and catenin. We also found associations of extrasynaptic NMDA receptors with the membrane associated guanylate kinase (MAGUKs), postsynaptic density (PSD)-95 and SAP102. Developmental differences were also observed. At postnatal day 2 in vivo, extrasynaptic NMDA receptors could often be found at sites with distinct densities whereas dense material was seen only rarely at sites of extrasynaptic NMDA receptors in the adult hippocampus in vivo. This difference probably indicates that many sites of extrasynaptic NMDA receptors in early postnatal ages represent synapse formation or possibly sites for synapse elimination. At all ages, as suggested in both in vivo and in vitro studies, extrasynaptic NMDA receptors on dendrites or the sides of spines may form complexes with other proteins, in many cases, at stable associations with adjacent cell processes. These associations may facilitate unique functions for extrasynaptic NMDA receptors.
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Affiliation(s)
- R S Petralia
- Laboratory of Neurochemistry, National Institute on Deafness and Other Communication Disorders/National Institutes of Health (NIDCD/NIH), Bethesda, MD, USA.
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22
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Cahusac PMB, Mavulati SC. Non-competitive metabotropic glutamate 1 receptor antagonists block activity of slowly adapting type I mechanoreceptor units in the rat sinus hair follicle. Neuroscience 2009; 163:933-41. [PMID: 19596050 DOI: 10.1016/j.neuroscience.2009.07.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2008] [Revised: 07/03/2009] [Accepted: 07/07/2009] [Indexed: 01/03/2023]
Abstract
Previous studies suggested that Group I metabotropic glutamate (mGlu) receptors play a role in mechanotransduction processes of slowly adapting type I mechanoreceptors. Using an isolated rat sinus hair follicle preparation we tested a range of compounds. Surprisingly, only non-competitive mGlu1 receptor antagonists produced profound and long-lasting depression of mechanically evoked firing. 6-Amino-N-cyclohexyl-N,3-dimethylthiazolo[3,2-alpha]benzimidazole-2-carboxamide hydrochloride (YM-298198) had an IC(50) of 8.7 muM (95% CI 5.7 to 13.2 microM), representing the most potent known blocker of type I mechanoreceptors. The derivative 6-amino-N-cyclohexyl-3-methylthiazolo[3,2-alpha]benzimidazole-2-carboxamide hydrochloride (desmethyl YM-298198) had a comparable potency. Another compound 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester (CPCCOEt) had a similar depressant effect, although it was less potent with an approximate IC(50) of 100 microM. Between three and seven times the concentration of CPCCOEt and YM-298198 respectively was required to produce similar depressions in slowly adapting type II units. No depression, and some weak excitatory effects, were observed using the following ligands: the competitive mGlu1 receptor antagonist alpha-amino-5-carboxy-3-methyl-2-thiopheneacetic acid (3-MATIDA) (300 microM), the phosphoserine phosphatase inhibitor dl-2-amino-3-phosphonopropionic acid (dl-AP3) (2 mM), non-competitive mGlu5 receptor antagonists 3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine; (S)-3,5-DHPG, (S)-3,5-dihydroxyphenylglycine (MTEP) (10 microM) and 2-methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP) (100 microM), the mGlu1 receptor agonist (S)-3,5-dihydroxyphenylglycine ((S)-3,5-DHPG) (500 microM), and the mGlu5 receptor agonist (RS)-2-chloro-5-hydroxyphenylglycine (CHPG) (1 mM). The results suggest that the non-competitive mGlu1 receptor antagonists are not acting at conventional mGlu1 receptors but at other binding sites, possibly those directly associated with mechanogated channels or on any of a number of indirect biochemical pathways. YM-298198 and related compounds may prove to be useful ligands to identify mechanosensitive channel proteins. The selective interference of type I units may provide further evidence that Merkel cells are mechanotransducers. Finally such compounds may deliver insights or treatments for Merkel cell carcinoma.
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Affiliation(s)
- P M B Cahusac
- Department of Psychology, University of Stirling, Stirling FK9 4LA, Scotland.
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23
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Ma MC, Huang HS, Chen YS, Lee SH. Mechanosensitive N-methyl-D-aspartate receptors contribute to sensory activation in the rat renal pelvis. Hypertension 2008; 52:938-44. [PMID: 18809793 DOI: 10.1161/hypertensionaha.108.114116] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The N-methyl-D-aspartate (NMDA) subtype of the ionotropic glutamate receptor is found in the periphery. The present study tested whether NMDA receptors (NMDARs) are present in the ends of afferent renal nerves in the renal pelvis, an area concerned mainly with transmitting sensation and the to reflex regulation of body fluid. The main NMDAR subunit, NMDAzeta1, was found to be more abundant in the renal pelvis than the renal cortex and medulla, and was mainly colocalized with the pan-neuronal marker PGP9.5 or the sensory nerve marker, the neurokinin-1 receptor. However, NMDAzeta1 mRNA was undetectable, suggesting that it might be synthesized outside the renal pelvis. Intrarenal arterial administration of the specific ion channel blocker (+)-MK-801, but not the inactive enantiomer (-)-MK-801, decreased urine output and sodium excretion. High doses of (+)-MK-801 also caused regional vasoconstriction in the renal cortex, as determined by laser-Doppler flowmetry. Intrapelvic administration of the NMDAR ligand D-serine caused a dose-dependent increase in substance P (SP) release and afferent renal nerve activity, but had no effect on arterial pressure. The D-serine-induced sensory activation and SP release were abrogated by (+)-MK-801, the SP receptor blocker L-703,606, or dorsal rhizotomy. Increasing intrapelvic pressure resulted in an increase in afferent renal nerve activity and a diuretic/natriuretic response. Interestingly, these effects were attenuated by prior administration of (+)-MK-801. These results indicate that NMDAR-positive sensory nerves are present in the renal pelvis and contribute to the renorenal reflex control of body fluid.
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Affiliation(s)
- Ming-Chieh Ma
- School of Medicine, Fu Jen Catholic University, Hsinchuang, Taiwan.
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24
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Abstract
Merkel cells are rare epidermal cells whose function in the skin is still debated. These cells localize to highly touch-sensitive areas of vertebrate epithelia, including palatine ridges, touch domes and finger tips. In most cases, Merkel cells complex with somatosensory afferents to form slowly adapting touch receptors; it is unclear, however, whether mechanosensory transduction occurs in the Merkel cell, the somatosensory afferent or both. Classic anatomical results suggests that Merkel cells are sensory cells that transduce mechanical stimuli and then communicate with sensory afferents via neurotransmission. This model is supported by recent molecular, immunohistochemical and physiological studies of Merkel cells in vitro and in intact tissues. For example, Merkel cells express essential components of presynaptic machinery, including molecules required for release of the excitatory neurotransmitter glutamate. Moreover, Merkel cells in vitro and in vivo are activated by mechanical stimuli, including hypotonic-induced cell swelling. Although these findings support the hypothesis that Merkel cells are sensory receptor cells, a definitive demonstration that Merkel cells are necessary and sufficient to transduce touch awaits future studies.
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Affiliation(s)
- Henry Haeberle
- Neuroscience Graduate Program, UCSF, Baylor College of Medicine, Houston TX 77030
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25
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Ebara S, Kumamoto K, Baumann KI, Halata Z. Three-dimensional analyses of touch domes in the hairy skin of the cat paw reveal morphological substrates for complex sensory processing. Neurosci Res 2008; 61:159-71. [DOI: 10.1016/j.neures.2008.02.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 02/13/2008] [Accepted: 02/15/2008] [Indexed: 10/22/2022]
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26
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Piskorowski R, Haeberle H, Panditrao MV, Lumpkin EA. Voltage-activated ion channels and Ca(2+)-induced Ca (2+) release shape Ca (2+) signaling in Merkel cells. Pflugers Arch 2008; 457:197-209. [PMID: 18415122 DOI: 10.1007/s00424-008-0496-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2007] [Revised: 03/03/2008] [Accepted: 03/13/2008] [Indexed: 12/24/2022]
Abstract
Ca(2+) signaling and neurotransmission modulate touch-evoked responses in Merkel cell-neurite complexes. To identify mechanisms governing these processes, we analyzed voltage-activated ion channels and Ca(2+) signaling in purified Merkel cells. Merkel cells in the intact skin were specifically labeled by antibodies against voltage-activated Ca(2+) channels (Ca(V)2.1) and voltage- and Ca(2+)-activated K(+) (BK(Ca)) channels. Voltage-clamp recordings revealed small Ca(2+) currents, which produced Ca(2+) transients that were amplified sevenfold by Ca(2+)-induced Ca(2+) release. Merkel cells' voltage-activated K(+) currents were carried predominantly by BK(Ca) channels with inactivating and non-inactivating components. Thus, Merkel cells, like hair cells, have functionally diverse BK(Ca) channels. Finally, blocking K(+) channels increased response magnitude and dramatically shortened Ca(2+) transients evoked by mechanical stimulation. Together, these results demonstrate that Ca(2+) signaling in Merkel cells is governed by the interplay of plasma membrane Ca(2+) channels, store release and K(+) channels, and they identify specific signaling mechanisms that may control touch sensitivity.
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Affiliation(s)
- Rebecca Piskorowski
- Department of Physiology, University of California, San Francisco, CA 94143, USA
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27
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Cahusac PMB, Noyce R. A pharmacological study of slowly adapting mechanoreceptors responsive to cold thermal stimulation. Neuroscience 2007; 148:489-500. [PMID: 17683869 DOI: 10.1016/j.neuroscience.2007.06.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2006] [Revised: 05/28/2007] [Accepted: 06/05/2007] [Indexed: 11/19/2022]
Abstract
Weber's silver Thaler illusion is the perception that cold objects appear heavier than warm objects. We were interested in studying the pharmacology of mechanoreceptor units that displayed increased spontaneous firing to cold stimuli. An isolated rat sinus hair preparation with intact nerve terminals was used to record the activity of two types of slowly adapting mechanoreceptors (St I and St II) during temperature ramps (0.91-1.73 degrees C/min) from normal bath temperature of 31+/-2 degrees C, cold to 14.5 degrees C and heat to 46 degrees C. Twenty-seven of the 43 mechanoreceptor units displayed marked increases in their spontaneous firing to cold or cooling thermal gradients, and were classified as cold mechanoreceptors. A high proportion (3:1) of St II units were responsive to cold than not, while the ratio was reversed for St I units (1:2). Most cold mechanoreceptor units showed decreases in mechanical responses to cold thermal gradients. Similar to specific cold thermoreceptors, many of the cold mechanoreceptor units briefly displayed increased spontaneous firing at higher (>41 degrees C) temperatures. The spontaneous firing of cold mechanoreceptor units was increased by the transient receptor potential (TRP) channel agonist icilin (30-100 microM) in a dose-dependent manner. Responses to mechanical stimulation were generally unaffected by icilin in these units, although their evoked response latencies were significantly reduced (similar to the effect of K+ channel blocker tetraethylammonium in St II units). TRPM8 channel agonist, (-) menthol 200 microM, had mixed effects on spontaneous firing but consistently enhanced cold responses. Other TRP agonists, cinnamaldehyde 1-2 mM and camphor 0.5-2 microM, reduced spontaneous and evoked responses. TRPA1 agonist allyl isothiocyanate (mustard oil) 50-100 microM and TRPV1 agonist capsaicin 1-3 microM had no effect. A broad spectrum TRP antagonist, Ruthenium Red 30 microM, had no effect. The TRPM8 antagonist, capsazepine 100-200 microM, blocked cold-evoked responses. Although these data generally provide support for the possibility that cooling responses are mediated by TRPM8 channels, the detailed profile of results suggests that another, as yet unidentified TRP channel, is involved. Multiplex coding of mechanical and thermal information by slowly adapting mechanoreceptors may play a functional role in thermal perception, and may explain Weber's silver Thaler illusion.
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Affiliation(s)
- P M B Cahusac
- Department of Psychology, University of Stirling, Stirling FK9 4LA, Scotland, UK.
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28
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Boulais N, Misery L. Merkel cells. J Am Acad Dermatol 2007; 57:147-65. [PMID: 17412453 DOI: 10.1016/j.jaad.2007.02.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Revised: 01/16/2007] [Accepted: 02/18/2007] [Indexed: 12/17/2022]
Abstract
Merkel cells are post-mitotic cells scattered throughout the epidermis of vertebrates. They are particularly interesting because of the close connections that they develop with sensory nerve endings and the number of peptides they can secrete. These features suggest that they may make an important contribution to skin homeostasis and cutaneous nerve development. However, these cells remain mysterious because they are difficult to study. They have not been successfully cultured and cannot be isolated, severely hampering molecular biology and functional analysis. Merkel cells probably originate in the neural crest of avians and mammalians, and their "spontaneous" appearance in the epidermis may be caused by a neuron-independent epidermal differentiation process. Their functions are still unclear: they take part in mechanoreception or at least interact with neurons, but little is known about their interactions with other epidermal cells. This review provides a new look at these least-known cells of the skin. The numerous peptides they synthesize and release may allow them to communicate with many cells other than neurons, and it is plausible that Merkel cells play a key role in skin physiology and physiopathology.
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Affiliation(s)
- Nicholas Boulais
- Unité de Physiologie Comparée et Intégrative, Université de Bretagne Occidentale, Brest, France
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29
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Dong XD, Mann MK, Kumar U, Svensson P, Arendt-Nielsen L, Hu JW, Sessle BJ, Cairns BE. Sex-related differences in NMDA-evoked rat masseter muscle afferent discharge result from estrogen-mediated modulation of peripheral NMDA receptor activity. Neuroscience 2007; 146:822-32. [PMID: 17382479 PMCID: PMC1976542 DOI: 10.1016/j.neuroscience.2007.01.051] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Revised: 01/25/2007] [Accepted: 01/30/2007] [Indexed: 10/23/2022]
Abstract
In the present study, the hypothesis that sex-related differences in glutamate-evoked rat masseter muscle afferent discharge may result from estrogen-related modulation of peripheral N-methyl-d-aspartate (NMDA) receptor activity and/or expression was tested by examining afferent fiber discharge in response to masseter injection of NMDA and the expression of NR2A/B subunits by masseter ganglion neurons in male and female rats. The results showed that injection of NMDA into the masseter muscle evoked discharges in putative mechanonociceptive afferent fibers and increased blood pressure that was concentration-dependent, however, a systemic action of NMDA appeared responsible for increased blood pressure. NMDA-evoked afferent discharge was significantly greater in female than in male rats, was positively correlated with plasma estrogen levels in females and was significantly greater in ovariectomized female rats treated with a high dose (5 mug/day) compared with a low dose (0.5 mug/day) of estrogen. Pre-treatment of high dose estrogen-treated-ovariectomized female rats with the Src tyrosine kinase inhibitor PP2 did not affect NMDA-evoked afferent discharge. NMDA-evoked afferent discharge was attenuated by the antagonists ketamine and ifenprodil, which is selective for NR2B containing NMDA receptors. Fewer masseter ganglion neurons expressed the NR2A (16%) subunit as compared with the NR2B subunit (38%), which was expressed at higher frequencies in intact female (46%) and high dose estrogen-treated ovariectomized female (60%) rats than in male (31%) rats. Taken together, these results suggest that sex-related differences in NMDA-evoked masseter afferent discharge are due, at least in part, to an estrogen-mediated increase in expression of peripheral NMDA receptors by masseter ganglion neurons in female rats.
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Affiliation(s)
- Xu-Dong Dong
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Mandeep K. Mann
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Ujendra Kumar
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Peter Svensson
- Department of Clinical Oral Physiology, Dental School, Århus University, DK-8000 Århus C, Denmark
| | - Lars Arendt-Nielsen
- Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction, Aalborg University, DK-9220, Denmark
| | - James W. Hu
- Faculty of Dentistry, The University of Toronto, Toronto, Ontario, M5G 1G6 Canada
| | - Barry J. Sessle
- Faculty of Dentistry, The University of Toronto, Toronto, Ontario, M5G 1G6 Canada
| | - Brian E. Cairns
- Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
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30
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Abstract
Sensory neurons innervating the skin encode the familiar sensations of temperature, touch and pain. An explosion of progress has revealed unanticipated cellular and molecular complexity in these senses. It is now clear that perception of a single stimulus, such as heat, requires several transduction mechanisms. Conversely, a given protein may contribute to multiple senses, such as heat and touch. Recent studies have also led to the surprising insight that skin cells might transduce temperature and touch. To break the code underlying somatosensation, we must therefore understand how the skin's sensory functions are divided among signalling molecules and cell types.
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Affiliation(s)
- Ellen A Lumpkin
- Departments of Neuroscience, Molecular Physiology & Biophysics and Molecular & Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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31
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Cahusac PMB, Senok SS. Metabotropic glutamate receptor antagonists selectively enhance responses of slowly adapting type I mechanoreceptors. Synapse 2006; 59:235-42. [PMID: 16385550 DOI: 10.1002/syn.20236] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
There is evidence that glutamate may participate as a transmitter at the junction between Merkel cells and the nerve terminals of slowly adapting type I (St I) units. We recorded extracellularly from the deep vibrissal nerve of an isolated rat vibrissa preparation in vitro. Five second trapezoid stimulus ramp deflections of the hair shaft were used to evoke responses. We bath-applied two compounds, which we planned would interfere with glutamatergic transmission. (2S)-2-Amino-2-[(1S,2S)-2-carboxycycloprop-1-yl]-3-(xanth-9-yl) propanoic acid (LY341495) was used at concentrations up to 100 microM to block all known metabotropic glutamate (mGlu) receptors. The racemic mixture (RS)-4-carboxy-3-hydroxyphenylglycine ((RS)-4C3HPG) was used up to 100 microM to block ionotropic and Group I metabotropic glutamate receptors, and as an agonist at Group II mGlu receptors. Unexpectedly, both compounds had rapid onset excitatory effects on mechanically-evoked responses. (RS)-4C3HPG increased responses, with a mean 146% of control (P < 0.05) in a concentration-dependent manner. LY341495 increased responses, with a mean 128% of control (P < 0.05). With (RS)-4C3HPG in particular, it was noted that the static component (the firing during the last 1 s plateau) was preferentially enhanced relative to the dynamic component (firing during the first 0.5 s). Rapid recovery was seen after wash. Slowly adapting type II units, which have no junctional transmission, were completely unaffected by these compounds up to 200 microM. These results suggest that mGlu receptors play a role in Merkel cell-neurite complex mechanotransduction, although other explanations are considered.
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Affiliation(s)
- Peter M B Cahusac
- Department of Psychology, University of Stirling, Stirling FK9 4LA, Scotland, UK.
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32
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Tachibana T, Nawa T. Immunohistochemical reactions of receptors to met-enkephalin, VIP, substance P, and CGRP located on Merkel cells in the rat sinus hair follicle. ACTA ACUST UNITED AC 2005; 68:383-91. [PMID: 16505584 DOI: 10.1679/aohc.68.383] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The role of Merkel cells in type I cutaneous mechanoreceptors remains enigmatic though mechanical transduction or neuromodulation function has been proposed. It has been shown that mammalian Merkel cells express immunohistochemical reactions of met-enkephalin, VIP, substance P, and CGRP, though the reactivity differs between species. If any one of these peptides acts as a transmitter or modulator for Merkel nerve terminals, these structures must have a specific receptor for the substance. We therefore studied the immunohistochemical localization of the above-mentioned neuropeptides and their receptors in Merkel cell-nerve endings in rat whisker pads. Specimens were doubly stained with polyclonal antibodies to neuropeptides and their receptors combined with a monoclonal antibody to cytokeratin 20, which was used for the labeling of Merkel cells. Merkel cells in the rat sinus hair follicles showed positive immunoreactions for all peptides studied, whereas the immunoreactions of receptors to these peptides were localized on Merkel cell membranes but not on the axon terminals. These results suggest that neuropeptides released from Merkel cells act on Merkel cells themselves by an autocrine mechanism.
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Affiliation(s)
- Tamiko Tachibana
- Department of Oral Anatomy II, Iwate Medical University School of Dentistry, Morioka 020-8505, Japan.
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