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Postnatal Maturation of Glutamatergic Inputs onto Rat Jaw-closing and Jaw-opening Motoneurons. Neuroscience 2022; 480:42-55. [PMID: 34780923 DOI: 10.1016/j.neuroscience.2021.11.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 10/15/2021] [Accepted: 11/03/2021] [Indexed: 11/23/2022]
Abstract
Motoneurons that innervate the jaw-closing and jaw-opening muscles play a critical role in oro-facial behaviors, including mastication, suckling, and swallowing. These motoneurons can alter their physiological properties through the postnatal period during which feeding behavior shifts from suckling to mastication; however, the functional synaptic properties of developmental changes in these neurons remain unknown. Thus, we explored the postnatal changes in glutamatergic synaptic transmission onto the motoneurons that innervate the jaw-closing and jaw-opening musculatures during early postnatal development in rats. We measured miniature excitatory postsynaptic currents (mEPSCs) mediated by non-NMDA receptors (non-NMDA mEPSCs) and NMDA receptors in the masseter and digastric motoneurons. The amplitude, frequency, and rise time of non-NMDA mEPSCs remained unchanged among postnatal day (P)2-5, P9-12, and P14-17 age groups in masseter motoneurons, whereas the decay time dramatically decreased with age. The properties of the NMDA mEPSCs were more predominant at P2-5 masseter motoneurons, followed by reduction as neurons matured. The decay time of NMDA mEPSCs of masseter motoneurons also shortened remarkably across development. Furthermore, the proportion of NMDA/non-NMDA EPSCs induced in response to the electrical stimulation of the supratrigeminal region was quite high in P2-5 masseter motoneurons, and then decreased toward P14-17. In contrast to masseter motoneurons, digastric motoneurons showed unchanged properties in non-NMDA and NMDA EPSCs throughout postnatal development. Our results suggest that the developmental patterns of non-NMDA and NMDA receptor-mediated inputs vary among jaw-closing and jaw-opening motoneurons, possibly related to distinct roles of respective motoneurons in postnatal development of feeding behavior.
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Alhilou AM, Shimada A, Svensson CI, Ernberg M, Cairns BE, Christidis N. Density of nerve fibres and expression of substance P, NR2B-receptors and nerve growth factor in healthy human masseter muscle: An immunohistochemical study. J Oral Rehabil 2020; 48:35-44. [PMID: 33031568 PMCID: PMC7821289 DOI: 10.1111/joor.13109] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/07/2020] [Accepted: 10/01/2020] [Indexed: 11/30/2022]
Abstract
Background In skeletal muscle, free nerve endings are mostly located within the connective tissue. However, the distribution of sensory afferent fibres in healthy human masseter muscle tissues has not been studied. Objectives Primarily to investigate human masseter muscle nerve fibre densities as well as expression of NR2B receptors, substance P (SP) and nerve growth factor (NGF), and secondarily to compare this between a) nerve fibres associated with myocytes and within connective tissue; b) sexes; and c) ages. Methods Microbiopsies of the masseter muscle were obtained from 60 sex‐ and age‐matched healthy participants. Biopsy sections were analysed using immunohistochemistry and were visualised with a Leica TCS SPE confocal microscope. The Mann‐Whitney U test was used for statistical analyses. Results The density of nerve fibres within connective tissue was significantly greater than in nerve fibres associated with myocytes (P < .001). Nerve fibres within connective tissue expressed SP alone or together with NR2B significantly more often than those associated with myocytes (P < .001). The frequency of nerve fibres, which expressed SP alone or in combination with NR2B or NGF, was significantly greater in women than in men (P < .050). Moreover, the co‐expression of the three markers together was inversely correlated with age in women (P < .002). Conclusions There is a higher density and greater expression of sensory nerve fibres within the connective tissue than associated with myocytes in healthy human masseter muscle. This suggests that nerve fibres within connective tissue are more involved in nociception than nerve fibres associated with myocytes.
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Affiliation(s)
- Abdelrahman M Alhilou
- Devision of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, Scandinavian Center for Orofacial Neurosciences (SCON), Huddinge, Sweden.,Department of Restorative Dentistry, College of Dentistry, Umm Al-Qura University, Makkah al Mukarramah, Saudi Arabia
| | - Akiko Shimada
- Department of Geriatric Dentistry, Osaka Dental University, Osaka, Japan
| | - Camilla I Svensson
- Department of Physiology and Pharmacology, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Malin Ernberg
- Devision of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, Scandinavian Center for Orofacial Neurosciences (SCON), Huddinge, Sweden
| | - Brian E Cairns
- Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Nikolaos Christidis
- Devision of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, Scandinavian Center for Orofacial Neurosciences (SCON), Huddinge, Sweden
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Nagata S, Nakamura S, Nakayama K, Mochizuki A, Yamamoto M, Inoue T. Postnatal changes in glutamatergic inputs of jaw-closing motoneuron dendrites. Brain Res Bull 2016; 127:47-55. [PMID: 27568204 DOI: 10.1016/j.brainresbull.2016.08.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 07/15/2016] [Accepted: 08/23/2016] [Indexed: 11/26/2022]
Abstract
Dendrites of masseter (jaw-closing) motoneurons (MMNs) are well developed and ramify extensively throughout the trigeminal motor nucleus and often extend into the adjacent reticular formation. It is possible that the dendrites have active properties, which are altered with the development of the orofacial musculoskeletal system. Thus, we examined the changes in somatic voltage responses evoked by photostimulation of the MMN dendrites by laser photolysis of caged glutamate from postnatal day (P) 2-5 and 9-12 rats. We photostimulated 39 spots that were arranged around each recorded neuron in a concave shape and found that the dendritic stimulation induced somatic depolarization in the presence of tetrodotoxin in all MMNs. With increasing photostimulation intensity, the responses grew in amplitude up to a certain threshold, where a step-like increase in amplitude occurred. In 75% of P2-5 MMNs, the step-like increase in amplitude, which was blocked by 20μM D(-)-2-amino-5-phosphonovaleric acid application, corresponded to the NMDA spikes/plateau potentials. In contrast, at P9-12 the responses became significantly smaller in amplitude and shorter in duration and only one neuron out of 12 MMNs showed NMDA spikes/plateau potentials. These results suggest that the glutamatergic responses evoked by photostimulation of the MMN dendrites change during the first two postnatal weeks, and these changes may be involved in the transition from suckling to chewing during postnatal development.
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Affiliation(s)
- Shoko Nagata
- Department of Oral Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan; Department of Periodontology, Showa University School of Dentistry, 2-1-1 Kitasenzoku, Ohta-ku, Tokyo, 145-8515, Japan
| | - Shiro Nakamura
- Department of Oral Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan.
| | - Kiyomi Nakayama
- Department of Oral Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan
| | - Ayako Mochizuki
- Department of Oral Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan
| | - Matsuo Yamamoto
- Department of Periodontology, Showa University School of Dentistry, 2-1-1 Kitasenzoku, Ohta-ku, Tokyo, 145-8515, Japan
| | - Tomio Inoue
- Department of Oral Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan
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Ohara H, Tachibana Y, Fujio T, Takeda-Ikeda R, Sato F, Oka A, Kato T, Ikenoue E, Yamashiro T, Yoshida A. Direct projection from the lateral habenula to the trigeminal mesencephalic nucleus in rats. Brain Res 2015; 1630:183-97. [PMID: 26592775 DOI: 10.1016/j.brainres.2015.11.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 09/29/2015] [Accepted: 11/08/2015] [Indexed: 12/30/2022]
Abstract
Trigeminal mesencephalic nucleus (Vmes) neurons are primary afferents conveying deep sensation from the masticatory muscle spindles or the periodontal mechanoreceptors, and are crucial for controlling jaw movements. Their cell bodies exist in the brain and receive descending commands from a variety of cortical and subcortical structures involved in limbic (emotional) systems. However, it remains unclear how the lateral habenula (LHb), a center of negative emotions (e.g., pain, stress and anxiety), can influence the control of jaw movements. To address this issue, we examined whether and how the LHb directly projects to the Vmes by means of neuronal tract tracing techniques in rats. After injections of a retrograde tracer Fluorogold in the rostral and caudal Vmes, a number of neurons were labeled in the lateral division of LHb (LHbl) bilaterally, whereas a few neurons were labeled in the medial division of LHb (LHbm) bilaterally. After injections of an anterograde tracer, biotinylated dextranamine (BDA) in the LHbl, a small number of labeled axons were distributed bilaterally in the rostral and caudal levels of Vmes, where some labeled axonal boutons contacted the cell body of rostral and caudal levels of Vmes neurons bilaterally. After the BDA injection into the LHbm, however, no axons were labeled bilaterally in the rostral and caudal levels of Vmes. Therefore, the present study for the first time demonstrated the direct projection from the LHbl to the Vmes and the detailed projection patterns, suggesting that jaw movements are modulated by negative emotions that are signaled by LHbl neurons.
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Affiliation(s)
- Haruka Ohara
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan; Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Yoshihisa Tachibana
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Takashi Fujio
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Rieko Takeda-Ikeda
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan; Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Fumihiko Sato
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Ayaka Oka
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan; Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Takafumi Kato
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Etsuko Ikenoue
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Takashi Yamashiro
- Department of Orthodontics and Dentofacial Orthopedics, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Atsushi Yoshida
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
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Paik SK, Kwak MK, Bae JY, Yi HW, Yoshida A, Ahn DK, Bae YC. γ-Aminobutyric acid-, glycine-, and glutamate-immunopositive boutons on mesencephalic trigeminal neurons that innervate jaw-closing muscle spindles in the rat: Ultrastructure and development. J Comp Neurol 2012; 520:3414-27. [DOI: 10.1002/cne.23110] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Paik SK, Kwak WK, Bae JY, Na YK, Park SY, Yi HW, Ahn DK, Ottersen OP, Yoshida A, Bae YC. Development of γ-aminobutyric acid-, glycine-, and glutamate-immunopositive boutons on rat jaw-opening motoneurons. J Comp Neurol 2012; 520:1212-26. [DOI: 10.1002/cne.22771] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Paik SK, Park SK, Jin JK, Bae JY, Choi SJ, Yoshida A, Ahn DK, Bae YC. Ultrastructural analysis of glutamate-immunopositive synapses onto the rat jaw-closing motoneurons during postnatal development. J Neurosci Res 2010; 89:153-61. [DOI: 10.1002/jnr.22544] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 09/20/2010] [Accepted: 10/04/2010] [Indexed: 11/07/2022]
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Okamoto R, Enomoto A, Koizumi H, Tanaka S, Ishihama K, Kogo M. Long-term potentiation of intrinsic excitability in trigeminal motoneurons. Brain Res 2010; 1312:32-40. [DOI: 10.1016/j.brainres.2009.11.039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 11/16/2009] [Accepted: 11/18/2009] [Indexed: 10/20/2022]
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Paik SK, Lee HJ, Choi MK, Cho YS, Park MJ, Moritani M, Yoshida A, Kim YS, Bae YC. Ultrastructural analysis of glutamate-, GABA-, and glycine-immunopositive boutons from supratrigeminal premotoneurons in the rat trigeminal motor nucleus. J Neurosci Res 2009; 87:1115-22. [PMID: 19006082 DOI: 10.1002/jnr.21929] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The supratrigeminal region (Vsup) is important for coordination of smooth jaw movement. However, little is known about the synaptic connections of the Vsup premotoneurons with the trigeminal motor neurons. In the present study, we examined axon terminals of Vsup premotoneurons in the contralateral trigeminal motor nucleus (Vmo) by a combination of anterograde tracing with cholera toxin B-horseradish peroxidase (CTB-HRP), postembedding immunohistochemistry for the amino acid transmitters glutamate, GABA, and glycine, and electron microscopy. Tracer injections resulted in anterograde labeling of axon terminals of the Vsup premotoneurons in the motor trigeminal nucleus (Vmo). The labeled boutons in Vmo exhibited immunoreactivity for glutamate, GABA, or glycine: glutamate-immunopositive boutons (69%) were more frequently observed than GABA- or glycine-immunopositive boutons (19% and 12%, respectively). Although most labeled boutons (97%) made synaptic contacts with a single postsynaptic dendrite, a few glutamate-immunopositive boutons (3%) showed synaptic contact with two dendrites. No labeled boutons participated in axoaxonic synaptic contacts. Most labeled boutons (78%) were presynaptic to dendritic shafts, and the remaining 22% were presynaptic to somata or primary dendrites. A large proportion of GABA- or glycine-immunopositive boutons (40%) were presynaptic to somata or primary dendrites, whereas most glutamate-immunopositive boutons (86%) were presynaptic to dendritic shafts. These results indicate that axon terminals of Vsup premotoneurons show simple synaptic connection with Vmo neurons. This may provide the anatomical basis for the neural information processing responsible for jaw movement control.
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Affiliation(s)
- Sang Kyoo Paik
- Department of Oral Anatomy and Neurobiology, School of Dentistry, BK21, Kyungpook National University, Daegu, Korea
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10
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Takahashi M, Negishi T, Imamura M, Sawano E, Kuroda Y, Yoshikawa Y, Tashiro T. Alterations in gene expression of glutamate receptors and exocytosis-related factors by a hydroxylated-polychlorinated biphenyl in the developing rat brain. Toxicology 2009; 257:17-24. [DOI: 10.1016/j.tox.2008.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 12/01/2008] [Accepted: 12/02/2008] [Indexed: 01/06/2023]
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11
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Ishihama K, Kogo M, Wakisaka S, Turman JE. Prenatal development of NMDA receptor composition and function in trigeminal neurons. ACTA ACUST UNITED AC 2009; 68:321-35. [PMID: 16477151 DOI: 10.1679/aohc.68.321] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The prenatal development of neural circuits for rhythmical oral-motor behaviors used for feeding is essential for the survival of the newborn mammal. The N-methyl-D-aspartate (NMDA) receptor plays a critical role in brainstem circuits underlying postnatal oral-motor behaviors. To understand a role for the NMDA receptor in the emergence of sucking behavior we conducted physiological and immunohistochemical experiments using fetal rats. Physiology experiments examined the development of the NMDA dose response of the brainstem circuit responsible for generating rhythmical trigeminal activity by recording trigeminal motor outputs using an in vitro preparation. The high dose of NMDA agonist bath application affected the mean cycle duration of rhythmical trigeminal activity (RTA) at both embryonic day (E) 18-19 and E20-21 in comparison with standard concentration of NMDA agonist. NMDA receptor immunohistochemistry studies, using antibodies directed against subunits NR1, NR2A, NR2B, NR3A and NR3B were performed to determine the prenatal regulation of NMDA subunits in trigeminal motoneurons (Mo5), and mesencephalic trigeminal neurons (Me5) between E17 to E20. In Mo5, NR1, NR2A, NR2B and NR3A immunoreactivity was observed throughout the time frame sampled. NR3B immunoreactivity was not observed in Mo5 or Me5. In Mo5, there was a significant decrease in the percentage of NR2B immunoreactive neurons between E17 and E20, and a concurrent increase in the NR2A/NR2B ratio between E17 and E20. In Me5, NR1, NR2A and NR3A immunoreactivity was observed throughout the time frame sampled; a significant decrease in the percentage of NR2A immunoreactive neurons between E17 and E20, and NR3A immunoreactive neurons between E17 and E18 occurred. The timing of subunit changes between E17 and E18 is coincident with the prenatal emergence of rhythmical jaw movements, and in vitro rhythmical trigeminal activity, shown in earlier studies. Our data suggest that NMDA receptor plays an important role in the development and function of prenatal oral-motor circuits.
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Affiliation(s)
- Kohji Ishihama
- First Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Japan
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12
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Circadian mPer1 gene expression in mesencephalic trigeminal nucleus cultures. Brain Res 2008; 1214:84-93. [DOI: 10.1016/j.brainres.2008.03.041] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 03/06/2008] [Accepted: 03/13/2008] [Indexed: 11/17/2022]
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Lazarov NE. Neurobiology of orofacial proprioception. ACTA ACUST UNITED AC 2007; 56:362-83. [PMID: 17915334 DOI: 10.1016/j.brainresrev.2007.08.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 08/22/2007] [Indexed: 12/29/2022]
Abstract
Primary sensory fibers innervating the head region derive from neurons of both the trigeminal ganglion (TG) and mesencephalic trigeminal nucleus (MTN). The trigeminal primary proprioceptors have their cell bodies in the MTN. Unlike the TG cells, MTN neuronal somata are centrally located within the brainstem and receive synaptic inputs that potentially modify their output. They are a crucial component of the neural circuitry responsible for the generation and control of oromotor activities. Gaining an insight into the chemical neuroanatomy of the MTN is, therefore, of fundamental importance for the understanding of neurobiology of the head proprioceptive system. This paper summarizes the recent advances in our knowledge of pre- and postsynaptic mechanisms related to orofacial proprioceptive signaling in mammals. It first briefly describes the neuroanatomy of the MTN, which is involved in the processing of proprioceptive information from the face and oral cavity, and then focuses on its neurochemistry. In order to solve the puzzle of the chemical coding of the mammalian MTN, we review the expression of classical neurotransmitters and their receptors in mesencephalic trigeminal neurons. Furthermore, we discuss the relationship of neuropeptides and their corresponding receptors in relaying of masticatory proprioception and also refer to the interactions with other atypical neuromessengers and neurotrophic factors. In extension of previous inferences, we provide conclusive evidence that the levels of transmitters vary according to the environmental conditions thus implying the neuroplasticity of mesencephalic trigeminal neurons. Finally, we have also tried to give an integrated functional account of the MTN neurochemical profiles.
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Affiliation(s)
- Nikolai E Lazarov
- Department of Anatomy and Histology, Faculty of Medicine, Medical University-Sofia, 2, Zdrave Street, BG-1431 Sofia, Bulgaria.
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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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Hsiao CF, Gougar K, Asai J, Chandler SH. Intrinsic membrane properties and morphological characteristics of interneurons in the rat supratrigeminal region. J Neurosci Res 2007; 85:3673-86. [PMID: 17668857 DOI: 10.1002/jnr.21442] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The membrane properties and morphological features of interneurons in the supratrigeminal area (SupV) were studied in rat brain slices using whole-cell patch clamp recording techniques. We classified three morphological types of neurons as fusiform, pyramidal, and multipolar and four physiological types of neurons according to their discharge pattern in response to a 1-sec depolarizing current pulse from -80 mV. Single-spike neurons responded with a single spike, phasic neurons showed an initial burst of spikes and were silent during the remainder of the stimulus, delayed-firing (DF) neurons exhibited a slow depolarization and delay to initial spike onset, and tonic (T) neurons showed maintained a discharge throughout the stimulus pulse. In a subpopulation of neurons (10%), membrane depolarization to around -44 mV produced a rhythmic burst discharge (RB) that was associated with voltage-dependent subthreshold membrane oscillations. Both these phenomena were blocked by the sodium channel blocker riluzole at a concentration that did not affect the fast transient spike. Low doses of 4-AP, which blocks low-threshold K+ currents, transformed bursting into low-frequency tonic discharge. In contrast, bursting occurred with exposure to cadium, a calcium-channel blocker. This suggests that persistent sodium currents and low-threshold K+ currents have a role in intrinsic burst generation. Importantly, RB cells were most often associated with multipolar neurons that exhibited either a DF or a T discharge. Thus, the SupV contains a variety of physiological cell types with unique morphologies and discharge characteristics. Intrinsic bursting neurons form a unique group in this region. .
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Affiliation(s)
- Chie-Fang Hsiao
- Department of Physiological Science and the Brain Research Institute, University of California at Los Angeles, Los Angeles, CA 90095, USA
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16
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Paik SK, Bae JY, Park SE, Moritani M, Yoshida A, Yeo EJ, Choi KS, Ahn DK, Moon C, Shigenaga Y, Bae YC. Developmental changes in distribution of γ-aminobutyric acid- and glycine-immunoreactive boutons on rat trigeminal motoneurons. I. Jaw-closing motoneurons. J Comp Neurol 2007; 503:779-89. [PMID: 17570498 DOI: 10.1002/cne.21423] [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] [Indexed: 11/10/2022]
Abstract
We have previously described the distribution pattern of inhibitory synapses on rat jaw-closing (JC) alpha- and gamma-motoneurons. In the present study, we investigated developmental changes in inhibitory synapses on JC motoneurons. We performed a quantitative ultrastructural analysis of putative inhibitory synaptic boutons on JC motoneuron somata by using postembedding immunogold labeling for GABA and glycine. In total, 206, 350, and 497 boutons contacting JC motoneuron somata were analyzed at postnatal days 2 (P2), 11 (P11) and 31 (P31), respectively. The size of the somata increased significantly during postnatal development. The size distribution was bimodal at P31. Mean length of the boutons and percentage of synaptic covering also increased during postnatal development, whereas bouton density did not differ significantly among the three age groups. Synaptic boutons on the somata of JC alpha-motoneurons could be classified into four types: boutons immunoreactive for 1) GABA only, 2) glycine only, 3) both GABA and glycine, and 4) neither GABA nor glycine. There was no developmental change in the proportion of putative inhibitory boutons to the total number of studied boutons. However, the glycine-only boutons increased significantly (15.1% to 27.3%), and the GABA-only boutons decreased significantly (17.7% to 2.6%) during the period from P11 to P31. Our ultrastructural data indicate that the inhibitory synaptic input to JC motoneurons is developmentally regulated and that there is a postnatal switch from GABA to glycine. The postnatal changes revealed in the present study could play an important role in the maturation of the oral motor system.
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Affiliation(s)
- Sang Kyoo Paik
- Department of Oral Anatomy and Neurobiology, School of Dentistry, Brain Korea 21, Kyungpook National University, Daegu 700-412, Korea
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Turman JE. The development of mastication in rodents: from neurons to behaviors. Arch Oral Biol 2006; 52:313-6. [PMID: 17055446 DOI: 10.1016/j.archoralbio.2006.08.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 08/22/2006] [Accepted: 08/24/2006] [Indexed: 10/24/2022]
Abstract
The development of suckling behavior is a fundamental characteristic of mammalian development. The occurrence of this behavior across mammals allows us to extrapolate information from animal models to better understand normal and abnormal masticatory development in infants. This review focuses on prenatal cell, molecular, and morphological changes in rat and/or mouse masticatory muscles, trigeminal motoneurons (Mo5) and mesencephalic trigeminal neurons (Me5) that accompany the development of suckling behavior. A special emphasis is placed on N-methyl-d-aspartate (NMDA) receptor subunit expression because of the important role that NMDA receptors play in the production of rhythmical jaw movements and neuronal development. Prenatally the timing of NMDA subunit changes follows neuromuscular junction formation in masticatory muscles, and is coincident with the emergence of rhythmical jaw movements and in vitro rhythmical trigeminal activity. Our data suggest that NMDA receptor subunit changes in Mo5 and Me5 are synchronized with the emergence of rhythmical jaw movements and trigeminal motor activity.
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Affiliation(s)
- Jack E Turman
- Center for Premature Infant Health and Development, Institute for Genetic Medicine, Keck School of Medicine, 1540 E. Alcazar Street, CHP 155, Los Angeles, CA 90089, USA.
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18
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Ishihama K, Turman JE. NR3 protein expression in trigeminal neurons during postnatal development. Brain Res 2006; 1095:12-6. [PMID: 16709403 DOI: 10.1016/j.brainres.2006.04.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Revised: 03/24/2006] [Accepted: 04/03/2006] [Indexed: 11/29/2022]
Abstract
The N-methyl-d-aspartate (NMDA) receptor plays an important role in the generation of rhythmical oral motor activities. To compliment our previous studies, we examined the developmental regulation of NR3A and NR3B expression in trigeminal motoneurons (Mo5) and mesencephalic trigeminal neurons (Me5). NR3A-immunoreactive neurons were observed at all ages in both nuclei, decreasing in Mo5 and caudal Me5 after P14, and increasing in rostral Me5. NR3B protein expression only emerged in Mo5 after P21-23. Results indicate that NR3A and NR3B expression is differentially regulated between Mo5 and Me5 coincident with the transition from suckling to chewing.
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Affiliation(s)
- Kohji Ishihama
- First Department of Oral and Maxillofacial Surgery, Osaka University Graduate School of Dentistry, Osaka 565-0871, Japan
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19
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Travers JB, Yoo JE, Chandran R, Herman K, Travers SP. Neurotransmitter phenotypes of intermediate zone reticular formation projections to the motor trigeminal and hypoglossal nuclei in the rat. J Comp Neurol 2005; 488:28-47. [PMID: 15912497 DOI: 10.1002/cne.20604] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Numerous studies suggest an essential role for the intermediate (IRt) and parvocellular (PCRt) reticular formation (RF) in consummatory ingestive responses. Although the IRt and PCRt contain a large proportion of neurons with projections to the oromotor nuclei, these areas of the RF are heterogeneous with respect to neurotransmitter phenotypes. Glutamatergic, GABAergic, cholinergic, and nitrergic neurons are all found in the PCRt and IRt, but the projections of neurons with these phenotypes to the motor trigeminal (mV) and hypoglossal nucleus (mXII) has not been fully evaluated. In the present study, after small injections of Fluorogold (FG) into mV and mXII, sections were processed immunohistochemically to detect retrogradely labeled FG neurons in combination with the synthetic enzymes for nitric oxide (nitric oxide synthase) or acetylcholine (choline acetyltransferase) or in situ hybridization for the synthetic enzyme for GABA (GAD65/67) or the brainstem vesicular transporter for glutamate (VGLUT2). In three additional cases, FG injections were made into one motor nucleus and cholera toxin (subunit b) injected in the other to determine the presence of dual projection neurons. Premotor neurons to mXII (pre-mXII) were highly concentrated in the IRt. In contrast, there were nearly equal proportions of premotor-trigeminal neurons (pre-mV) in the IRt and PCRt. A high proportion of pre-oromotor neurons were positive for VGLUT2 (pre-mXII: 68%; pre-mV: 53%) but GABAergic projections were differentially distributed with a greater projection to mV (25%) compared to mXII (8%). Significant populations of cholinergic and nitrergic neurons overlapped pre-oromotor neurons, but there was sparse double-labeling (<10%). The IRt also contained a high proportion of neurons that projected to both mV and MXII. These different classes of premotor neurons in the IRt and PCRt provide a substrate for the rhythmic activation of lingual and masticatory muscles.
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Affiliation(s)
- Joseph B Travers
- College of Dentistry, Ohio State University, Section of Oral Biology, Columbus, 43210, USA.
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Verdier D, Lund JP, Kolta A. Synaptic Inputs to Trigeminal Primary Afferent Neurons Cause Firing and Modulate Intrinsic Oscillatory Activity. J Neurophysiol 2004; 92:2444-55. [PMID: 15381749 DOI: 10.1152/jn.00279.2004] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this paper, we investigated the influence of synapses on the cell bodies of trigeminal muscle spindle afferents that lie in the trigeminal mesencephalic nucleus (NVmes), using intracellular recordings in brain stem slices of young rats. Three types of synaptic responses could be evoked by electrical stimulation of the adjacent supratrigeminal, motor, and main sensory nuclei and the intertrigeminal area: monophasic depolarizing postsynaptic potentials (PSPs), biphasic PSPs, and all or none action potentials without underlying excitatory PSPs (EPSPs). Many PSPs and spikes were abolished by bath-application of 6,7-dinitroquinoxaline (DNQX) alone or combined with d,l-2-amino-5-phosphonovaleric acid (APV), suggesting that they are mediated by non– N-methyl-d-aspartate (NMDA) and NMDA glutamatergic receptors, while some action potentials were sensitive to bicuculline, indicating involvement of GABAA receptors. A number of cells showed spontaneous membrane potential oscillations, and stimulation of synaptic inputs increased the amplitude of the oscillations for several cycles, which often triggered repetitive firing. Furthermore, the oscillatory rhythm was reset by the stimulation. Our results show that synaptic inputs to muscle primary afferent neurons in NVmes from neighboring areas are mainly excitatory and that they cause firing. In addition, the inputs synchronize intrinsic oscillations, which may lead to sustained, synchronous firing in a subpopulation of afferents. This may be of importance during rapid biting and during the mastication of very hard or tough foods.
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Affiliation(s)
- Dorly Verdier
- Centre de Recherche en Sciences Neurologiques, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
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Honma S, De S, Li D, Shuler CF, Turman JE. Developmental regulation of connexins 26, 32, 36, and 43 in trigeminal neurons. Synapse 2004; 52:258-71. [PMID: 15103692 DOI: 10.1002/syn.20022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The transition from sucking to chewing during postnatal development is accompanied by changes in masticatory muscle activity patterns. We previously demonstrated that changes in numerous parameters of chemical synapses among neurons, and intrinsic membrane properties of neurons, comprising brainstem oral-motor circuits are coincident with changes in masticatory muscle activity patterns. Considering recent findings that implicate a role for gap junctions in early locomotor and respiratory behaviors, our present study focuses on the developmental regulation of connexin proteins in trigeminal neurons as a first step in understanding a role for gap junctions in developing oral-motor circuits used for ingestive behaviors. We conducted immunohistochemistry studies to examine connexin (Cx) 26, 32, 36, and 43 expression in trigeminal motor and mesencephalic trigeminal nuclei during postnatal development at the light and electron microscopic levels. Postnatal days (P) 1, 6, 14, 21, and adult mice were used. Cx32, 36, and 43 expression was developmentally regulated in the trigeminal motor nucleus, while Cx26 expression remained high throughout postnatal development. In the mesencephalic trigeminal nucleus, Cx26, 32, and 43 expression was intense throughout development, with only Cx36 showing a developmental regulation. Ultrastructural examination of neonatal trigeminal motoneurons and mesencephalic trigeminal neurons revealed connexin expression in cell membranes, cytoplasm, and cell nuclei (Cx43, Cx32). Our results show that connexin proteins are differentially regulated between trigeminal motoneurons and mesencephalic trigeminal neurons during development, and suggest a possible role for gap junctions in the development of trigeminal neurons and the function and maturation of oral-motor circuits.
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Affiliation(s)
- Shiho Honma
- Center for Craniofacial Molecular Biology, University of Southern California, Los Angeles, California 90089, USA
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Ishihama K, Kogo M, Koizumi H, Nomura K, Tanaka S, Yamanishi T, Enomoto A. Oral-motor patterns of rhythmic trigeminal activity generated in fetal rat brainstem in vitro. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 145:163-6. [PMID: 14519503 DOI: 10.1016/s0165-3806(03)00220-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Development of neural circuits generating fetal oral-motor activity was characterized in an in vitro isolated brainstem block preparation. Rhythmical trigeminal activity (RTA) at E20-E21 resembled either the pattern or rhythm of neonatal RTA. Conversely, at E18-E19, RTA displayed a different pattern of discharge from neonatal RTA, and output was not regular but intermittent with another slow rhythm.
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Affiliation(s)
- Kohji Ishihama
- First Department of Oral & Maxillofacial Surgery, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita, Osaka 565-0871, Japan
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Machaalani R, Waters KA. Distribution and quantification of NMDA R1 mRNA and protein in the piglet brainstem and effects of intermittent hypercapnic hypoxia (IHH). Brain Res 2002; 951:293-300. [PMID: 12270508 DOI: 10.1016/s0006-8993(02)03175-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The first aim of this study was to determine the cellular distribution of NR1 in the piglet brainstem. Documentation of NR1 mRNA was by non-radioactive in situ hybridisation (non-RISH) and of NR1 protein by immunohistochemistry. We found that all neurons expressed mRNA but not all had NR1 protein. Application of non-RISH has permitted us, for the first time, to document the cellular localization of NR1 mRNA showing that it was present in the cytoplasm and nucleolus of motor neurons but dispersed throughout the cellular compartments of sensory neurons. NR1 protein on the other hand, was localized to the cytoplasm only. The second aim of this study was to quantify the distribution of NR1 mRNA and protein. Using image analysis software, we used optical density (OD) to quantify the non-RISH signal for mRNA and cellular counting for protein (expressed as % positive). Results show that NR1 expression is greater in motor than sensory nuclei; for mRNA: 0.46+/-0.04 vs. 0.31+/-0.02 OD units (P<0.001), for protein: 75.9+/-3.1 vs. 58.4+/-2.5% positive (P<0.001). The third aim of this study was to determine the effects of intermittent hypercapnic hypoxia (IHH) on NR1 expression. Chronic IHH exposure caused differential changes in mRNA and protein expression. NR1 mRNA expression increased while the number of neurons expressing NR1 protein showed no change. This finding suggests that NMDA pathways are activated by exposure to IHH.
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Affiliation(s)
- Rita Machaalani
- Department of Medicine, Room 206 Blackburn Building, DO6, University of Sydney, Sydney, NSW 2006, Australia
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24
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Honma S, Varathan V, Wakisaka S. Postnatal development of synaptic inputs to rat masseter motoneurons. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2002; 139:67-71. [PMID: 12414095 DOI: 10.1016/s0165-3806(02)00518-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We examined postnatal changes in rat masseter motoneuron morphology and the density of synaptic inputs to masseter motoneurons using retrograde labeling combined with synaptophysin immunohistochemistry. The cross-sectional area and perimeter of masseter motoneurons increased through P21 whereas synaptic input density increased throughout the time frame sampled. Data suggest that changes in masseter motoneuron morphology and the density of its synaptic input contribute to the maturation of mastication behavior.
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Affiliation(s)
- Shiho Honma
- Department of Oral Anatomy and Developmental Biology, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita, Osaka, 565-0871 Japan
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25
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Turman JE, Lee OK, Chandler SH. Differential NR2A and NR2B expression between trigeminal neurons during early postnatal development. Synapse 2002; 44:76-85. [PMID: 11891879 DOI: 10.1002/syn.10059] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
N-methyl-D-aspartate (NMDA) receptors play an important role in the production of rhythmical trigeminal motor activity resembling suckling and chewing. The developmental relationship between the expression of NMDA receptor subunits and the function of neurons comprising brainstem oral-motor circuitry is not clear. We conducted receptor immunohistochemistry studies to demonstrate the expression of NR2A and NR2B subunits in trigeminal motoneurons (Mo5) and mesencephalic trigeminal neurons (Me5) during the first 2 weeks of development. During this time period, rats begin the transition from suckling to chewing, two distinct motor behaviors. In Mo5, NR2A and NR2B immunoreactivity was observed throughout the time frame sampled. A significant increase in the NR2A:NR2B ratio occurred between P3-4 and P11 due to a reduction in the number of NR2B immunoreactive neurons. The temporal and spatial expression of NR2A and NR2B was differentially regulated between caudal and rostral regions of Me5. In contrast to Mo5, the NR2A:NR2B ratio decreased between P0-1 and P11 in caudal Me5 due to a concurrent increase in the number of NR2A and NR2B immunoreactive neurons. In rostral Me5, NR2A and NR2B immunoreactivity emerged at P3 and P11, respectively. Our data provides further insight into the molecular changes of trigeminal neurons during the transition from suckling to chewing behaviors. The differences in the NR2A:NR2B ratio between Mo5 and Me5 suggest functional differences in these neurons during NMDA-mediated neurotransmission.
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Affiliation(s)
- Jack E Turman
- Department of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, California 90089, USA.
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Hsiao CF, Wu N, Levine MS, Chandler SH. Development and serotonergic modulation of NMDA bursting in rat trigeminal motoneurons. J Neurophysiol 2002; 87:1318-28. [PMID: 11877506 DOI: 10.1152/jn.00469.2001] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The development of N-methyl-D-aspartate (NMDA)-induced burst discharge in rat trigeminal motoneurons (TMNs) between postnatal days P1 and P10 was examined using whole cell patch-clamp recording methods in brain slices. Bath application of NMDA (50 microM) induced a Mg(2+)-dependent rhythmical bursting activity starting around P8. Prior to the onset of bursting, the membrane potential depolarized and the input resistance increased. Hyperpolarization of the membrane potential with extrinsic current demonstrated a narrow window of membrane potential where maintained rhythmical burst discharge was evident. In P1-P4 neurons, NMDA application produced membrane depolarization and a minimal change in input resistance, but no burst activity at any membrane potential. Voltage-clamp analysis indicated that the bursting activity was related to the presence or absence of a voltage-dependent Mg(2+) block and induction of a negative slope conductance (NSC) region in the I(NMDA)-V relationship. Regardless of age, reduction of extracellular Mg(2+) from 1 mM to 30 microM enhanced I(NMDA) at voltages negative to -60 mV. However, in 1 mM Mg(2+), P1-P4 neurons were devoid of a prominent NSC region compared with P8-P10 neurons, suggesting that the efficacy of depolarization in unblocking the NMDA receptors increased with age. NMDA bursting was not dependent on calcium influx through voltage-gated calcium channels (VGCC) but did require a minimal concentration of Ca(2+) in the bath. Intracellular bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid application suppressed burst discharge completely, suggesting that intracellular Ca(2+) directly, or via second-messenger systems, regulates NMDA receptor activity and bursting. Interestingly, NMDA bursting could be induced in P1-P4 neurons by simultaneous bath application of serotonin (5-HT, 10 microM), which by itself did not produce bursting, suggesting an "enabling" role for 5-HT. Voltage-clamp analysis demonstrated that the NMDA/5-HT bursting resulted from induction of an NSC in the I-V relationship of total membrane current. 5-HT by itself produced no such effect. The mechanisms for this effect were due to an enhancement of the NSC region of the I(NMDA)-V relationship and reduction of a presumed leak current by 5-HT. These data indicate that NMDA bursting in trigeminal motoneurons is developmentally regulated and subject to neuromessenger modulation. Control of the Mg(2+) sensitivity of the NMDA receptor and voltage-dependent block by neuromessengers could be an effective means to control the efficacy of glutamatergic synaptic drive to motoneurons during rhythmical oral-motor activity at early postnatal ages.
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Affiliation(s)
- Chie-Fang Hsiao
- Department of Physiological Science, University of California at Los Angeles, 2859 Slichter Hall, Los Angeles, CA 90095-1568, USA
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Lazarov NE. Comparative analysis of the chemical neuroanatomy of the mammalian trigeminal ganglion and mesencephalic trigeminal nucleus. Prog Neurobiol 2002; 66:19-59. [PMID: 11897404 DOI: 10.1016/s0301-0082(01)00021-1] [Citation(s) in RCA: 189] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A characteristic peculiarity of the trigeminal sensory system is the presence of two distinct populations of primary afferent neurons. Most of their cell bodies are located in the trigeminal ganglion (TG) but part of them lie in the mesencephalic trigeminal nucleus (MTN). This review compares the neurochemical content of central versus peripheral trigeminal primary afferent neurons. In the TG, two subpopulations of primary sensory neurons, containing immunoreactive (IR) material, are identified: a number of glutamate (Glu)-, substance P (SP)-, neurokinin A (NKA)-, calcitonin gene-related peptide (CGRP)-, cholecystokinin (CCK)-, somatostatin (SOM)-, vasoactive intestinal polypeptide (VIP)- and galanin (GAL)-IR ganglion cells with small and medium-sized somata, and relatively less numerous larger-sized neuropeptide Y (NPY)- and peptide 19 (PEP 19)-IR trigeminal neurons. In addition, many nitric oxide synthase (NOS)- and parvalbumin (PV)-IR cells of all sizes as well as fewer, mostly large, calbindin D-28k (CB)-containing neurons are seen. The majority of the large ganglion cells are surrounded by SP-, CGRP-, SOM-, CCK-, VIP-, NOS- and serotonin (SER)-IR perisomatic networks. In the MTN, the main subpopulation of large-sized neurons display Glu-immunoreactivity. Additionally, numerous large MTN neurons exhibit PV- and CB-immunostaining. On the other hand, certain small MTN neurons, most likely interneurons, are found to be GABAergic. Furthermore, NOS-containing neurons can be detected in the caudal and the mesencephalic-pontine junction portions of the nucleus. Conversely, no immunoreactivity to any of the examined neuropeptides is observed in the cell bodies of MTN neurons but these are encircled by peptidergic, catecholaminergic, serotonergic and nitrergic perineuronal arborizations in a basket-like manner. Such a discrepancy in the neurochemical features suggests that the differently fated embryonic migration, synaptogenesis, and peripheral and central target field innervation can possibly affect the individual neurochemical phenotypes of trigeminal primary afferent neurons.
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Affiliation(s)
- Nikolai E Lazarov
- Department of Anatomy, Faculty of Medicine, Thracian University, 11 Armejska Street, BG-6003 Stara Zagora, Bulgaria.
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Bourque MJ, Kolta A. Properties and interconnections of trigeminal interneurons of the lateral pontine reticular formation in the rat. J Neurophysiol 2001; 86:2583-96. [PMID: 11698544 DOI: 10.1152/jn.2001.86.5.2583] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Numerous evidence suggests that interneurons located in the lateral tegmentum at the level of the trigeminal motor nucleus contribute importantly to the circuitry involved in mastication. However, the question of whether these neurons participate actively to genesis of the rhythmic motor pattern or simply relay it to trigeminal motoneurons remains open. To answer this question, intracellular recordings were performed in an in vitro slice preparation comprising interneurons of the peritrigeminal area (PeriV) surrounding the trigeminal motor nucleus (NVmt) and the parvocellular reticular formation ventral and caudal to it (PCRt). Intracellular and extracellular injections of anterograde tracers were also used to examine the local connections established by these neurons. In 97% of recordings, electrical stimulation of adjacent areas evoked a postsynaptic potential (PSP). These PSPs were primarily excitatory, but inhibitory and biphasic responses were also induced. Most occurred at latencies longer than those required for monosynaptic transmission and were considered to involve oligosynaptic pathways. Both the anatomical and physiological findings show that all divisions of PeriV and PCRt are extensively interconnected. Most responses followed high-frequency stimulation (50 Hz) and showed little variability in latency indicating that the network reliably distributes inputs across all areas. In all neurons but one, excitatory postsynaptic potentials (EPSPs) or inhibitory postsynaptic potentials (IPSPs) were also elicited by stimulation of NVmt, suggesting the existence of excitatory and inhibitory interneurons within the motor nucleus. In a number of cases, these PSPs were reproduced by local injection of glutamate in lieu of the electrical stimulation. All EPSPs induced by stimulation of PeriV, PCRt, or NVmt were sensitive to ionotropic glutamate receptor antagonists 6-cyano-7-dinitroquinoxaline and D,L-2-amino-5-phosphonovaleric acid, while IPSPs were blocked by bicuculline and strychnine, antagonists of GABA(A) and glycine receptors. Examination of PeriV and PCRt intrinsic properties indicate that they form a fairly uniform network. Three types of neurons were identified on the basis of their firing adaptation properties. These types were not associated with particular regions. Only 5% of all neurons showed bursting behavior. Our results do not support the hypothesis that neurons of PeriV and PCRt participate actively to rhythm generation, but suggest instead that they are driven by rhythmical synaptic inputs. The organization of the network allows for rapid distribution of this rhythmic input across premotoneuron groups.
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Affiliation(s)
- M J Bourque
- Département de Stomatologie, Faculté de Médecine Dentaire and Centre de Recherche en Sciences Neurologiques, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
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29
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Turman JE, Rich RA, Chandler SH. GABA(A) receptor beta2/beta3 subunit and GAD67 immunoreactivity in the trigeminal motor nucleus during early postnatal development. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2001; 130:155-8. [PMID: 11557106 DOI: 10.1016/s0165-3806(01)00227-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
GABA neurotransmission plays a role in brainstem circuitry responsible for jaw movements. We investigated the developmental relationship between terminals expressing GAD67 and GABA(A) receptor beta(2)/beta(3) subunit expression within the trigeminal motor nucleus. GAD67 immunoreactivity was intense throughout development. Neuropilar beta(2)/beta(3) immunoreactivity emerged during the 2nd postnatal week. Our data provide anatomical evidence for a GABAergic innervation of neonatal trigeminal motoneurons and suggest that beta(2)/beta(3) subunit expression is developmentally regulated in trigeminal motoneurons.
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Affiliation(s)
- J E Turman
- Department of Biokinesiology and Physical Therapy, University of Southern California, 1540 Alcazar St., CHP155 Los Angeles, CA 90089, USA.
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30
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Abstract
Our intent in this review was to consider the relationship between the biophysical properties of motoneurons and the mechanisms by which they transduce the synaptic inputs they receive into changes in their firing rates. Our emphasis has been on experimental results obtained over the past twenty years, which have shown that motoneurons are just as complex and interesting as other central neurons. This work has shown that motoneurons are endowed with a rich complement of active dendritic conductances, and flexible control of both somatic and dendritic channels by endogenous neuromodulators. Although this new information requires some revision of the simple view of motoneuron input-output properties that was prevalent in the early 1980's (see sections 2.3 and 2.10), the basic aspects of synaptic transduction by motoneurons can still be captured by a relatively simple input-output model (see section 2.3, equations 1-3). It remains valid to describe motoneuron recruitment as a product of the total synaptic current delivered to the soma, the effective input resistance of the motoneuron and the somatic voltage threshold for spike initiation (equations 1 and 2). However, because of the presence of active channels activated in the subthreshold range, both the delivery of synaptic current and the effective input resistance depend upon membrane potential. In addition, activation of metabotropic receptors by achetylcholine, glutamate, noradrenaline, serotonin, substance P and thyrotropin releasing factor (TRH) can alter the properties of various voltage- and calcium-sensitive channels and thereby affect synaptic current delivery and input resistance. Once motoneurons are activated, their steady-state rate of repetitive discharge is linearly related to the amount of injected or synaptic current reaching the soma (equation 3). However, the slope of this relation, the minimum discharge rate and the threshold current for repetitive discharge are all subject to neuromodulatory control. There are still a number of unresolved issues concerning the control of motoneuron discharge by synaptic inputs. Under dynamic conditions, when synaptic input is rapidly changing, time- and activity-dependent changes in the state of ionic channels will alter both synaptic current delivery to the spike-generating conductances and the relation between synaptic current and discharge rate. There is at present no general quantitative expression for motoneuron input-output properties under dynamic conditions. Even under steady-state conditions, the biophysical mechanisms underlying the transfer of synaptic current from the dendrites to the soma are not well understood, due to the paucity of direct recordings from motoneuron dendrites. It seems likely that resolving these important issues will keep motoneuron afficiandoes well occupied during the next twenty years.
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Affiliation(s)
- R K Powers
- Department of Physiology & Biophysics, University of Washington School of Medicine, Box 357290, Seattle, Washington 98195-7290, USA
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Turman JE, MacDonald AS, Pawl KE, Bringas P, Chandler SH. AMPA receptor subunit expression in trigeminal neurons during postnatal development. J Comp Neurol 2000; 427:109-23. [PMID: 11042594 DOI: 10.1002/1096-9861(20001106)427:1<109::aid-cne7>3.0.co;2-t] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Trigeminal motoneurons (Mo5) and mesencephalic trigeminal neurons (Me5) are important constituents of the neural circuitry responsible for jaw movements. Non-N-methyl-D-aspartate (NMDA) glutamate receptors are a critical component of the brainstem circuitry responsible for reflex and centrally activated jaw movements; however, little is known about the expression of these receptors in neonatal oral-motor circuitry. Receptor immunohistochemistry using affinity-purified polyclonal antibodies directed against GluR1, GluR2/3/4c, and GluR4, respectively, and a monoclonal antibody directed against the GluR2 subunit, were used in rats at postnatal day (P)1, P3, P5, P10, P19-21, P32-35, and P60 to describe the expression of the alpha-amino-d-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor in Mo5 and Me5 neurons. In Mo5, immunoreactivity was noted for all antibodies throughout the time frame sampled. Neurons in caudal portions of Me5 displayed immunoreactivity to each antibody except at P60 when GluR2 immunoreactivity was absent. Neurons located in rostral Me5 displayed GluR2/3/4c and GluR4 immunoreactivity throughout the time frame, GluR1 immunoreactivity emerged at P3 and a transient expression of GluR2 expression was observed between P10 and P32-35. The lack of labeling of some neurons in both regions, coupled with differences in temporal expression, suggests that there are differences in the AMPA receptor phenotype within and between Mo5 and Me5 during postnatal development. Differences in AMPA subunit composition suggest a complex role for AMPA-mediated glutamatergic neurotransmission in brainstem circuits controlling jaw movements.
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Affiliation(s)
- J E Turman
- University of Southern California, Department of Biokinesiology and Physical Therapy, Los Angeles, California 90089, USA. turman@hsc,usc.edu
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