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2.
J Stroke Cerebrovasc Dis ; 30(4): 105623, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33486342

RESUMO

In the present report, we discussed the case of a 57-year-old man with unilateral masticatory muscle weakness, nystagmus, skew deviation and facial hypesthesia due to pontine tegmental infarction. Trigeminal motor neuropathy attributed to brain infarction is very rare. Brain magnetic resonance imaging revealed a small dot-like infarction lesion in the pontine tegmentum. Masticatory muscle weakness was confirmed by an electrophysiological study performed on the day after admission in which there was an incomplete interference pattern without spontaneous denervation activity, suggesting that the patient's masseter muscle weakness was caused by an infarction of the trigeminal motor nucleus proper or trigeminal motor nerve fascicles rather than Wallerian degeneration of the trigeminal nerve or the progression of masseter muscle degeneration.


Assuntos
Infartos do Tronco Encefálico/complicações , Paralisia Facial/etiologia , Músculo Masseter/inervação , Debilidade Muscular/etiologia , Núcleo Motor do Nervo Trigêmeo/irrigação sanguínea , Doenças do Nervo Trigêmeo/etiologia , Doença Aguda , Infartos do Tronco Encefálico/diagnóstico por imagem , Infartos do Tronco Encefálico/fisiopatologia , Paralisia Facial/diagnóstico , Paralisia Facial/fisiopatologia , Humanos , Masculino , Mastigação , Pessoa de Meia-Idade , Debilidade Muscular/diagnóstico , Debilidade Muscular/fisiopatologia , Doenças do Nervo Trigêmeo/diagnóstico , Doenças do Nervo Trigêmeo/fisiopatologia
3.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 55(4): 259-263, 2020 Apr 09.
Artigo em Chinês | MEDLINE | ID: mdl-32268626

RESUMO

Objective: To determine the opening and closing action of the external muscle, the projection pathway of the axon terminal of trigeminal motor nucleus (Vmo) neuron to the lateral pterygoid muscle was revealed. Methods: In this study, 10 SD rats of 8 weeks old were included. The left lateral pterygoid muscle of SD rats was surgically exposed, and the wound was closed after intramuscular injection of hydroxystilbamidine/fluorogold (FG) 3-5 µl. Seven days after the operation, the experimental animals were perfused, samples collected and sectioned for immunofluorescence staining. After FG injection into the lateral pterygoid muscle, the FG reversed in the Vmo neurons. Results: In the Vmo neurons on the FG injection side (left side), a large number of FG reversed neurons were found in the corpus luteum and dendrites. These neurons were not only distributed in the dorsolateral part of the trigeminal motor nucleus that innervated the closed muscle, but also in the ventral medial portion of the trigeminal nucleus of the open muscle. Conclusions: The neuronal conduction pathway between the Vmo and the lateral pterygoid muscle innervates the lateral pterygoid muscle. The neurons are distributed both in the dorsolateral and in the nucleus of the ventral ventricle. It is concluded that the lateral pterygoid muscle involve in the jaw closing and opening movement.


Assuntos
Músculos Pterigoides , Núcleo Motor do Nervo Trigêmeo , Animais , Feminino , Arcada Osseodentária , Movimento , Neurônios , Músculos Pterigoides/anatomia & histologia , Músculos Pterigoides/inervação , Ratos , Ratos Sprague-Dawley , Núcleo Motor do Nervo Trigêmeo/anatomia & histologia , Núcleos do Trigêmeo
4.
J Vis Exp ; (153)2019 11 26.
Artigo em Inglês | MEDLINE | ID: mdl-31840660

RESUMO

Current scientific literature provides evidence that trigeminal sensorimotor activity associated with chewing may affect arousal, attention, and cognitive performance. These effects may be due to widespread connections of the trigeminal system to the ascending reticular activating system (ARAS), to which noradrenergic neurons of the locus coeruleus (LC) belongs. LC neurons contain projections to the whole brain, and it is known that their discharge co-varies with pupil size. LC activation is necessary for eliciting task-related mydriasis. If chewing effects on cognitive performance are mediated by the LC, it is reasonable to expect that changes in cognitive performance are correlated to changes in task-related mydriasis. Two novel protocols are presented here to verify this hypothesis and document that chewing effects are not attributable to aspecific motor activation. In both protocols, performance and pupil size changes observed during specific tasks are recorded before, soon after, and half an hour following a 2 min period of either: a) no activity, b) rhythmic, bilateral handgrip, c) bilateral chewing of soft pellet, and d) bilateral chewing of hard pellet. The first protocol measures level of performance in spotting target numbers displayed within numeric matrices. Since pupil size recordings are recorded by an appropriate pupillometer that impedes vision to ensure constant illumination levels, task-related mydriasis is evaluated during a haptic task. Results from this protocol reveal that 1) chewing-induced changes in performance and task-related mydriasis are correlated and 2) neither performance nor mydriasis are enhanced by handgrip. In the second protocol, use of a wearable pupillometer allows measurement of pupil size changes and performance during the same task, thus allowing even stronger evidence to be obtained regarding LC involvement in the trigeminal effects on cognitive activity. Both protocols have been run in the historical office of Prof. Giuseppe Moruzzi, the discoverer of ARAS, at the University of Pisa.


Assuntos
Nível de Alerta/fisiologia , Locus Cerúleo/fisiologia , Pupila/fisiologia , Núcleo Motor do Nervo Trigêmeo/fisiologia , Cognição/fisiologia , Humanos , Locus Cerúleo/citologia , Masculino , Mastigação/fisiologia , Neurônios/fisiologia
5.
Med Hypotheses ; 130: 109280, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31383322

RESUMO

There is large support in literature linking tinnitus to dental occlusion and temporomandibular joint disorders (TMD). However, there is no model to explain such a link. This hypothesis explains how the fusimotor system of the muscles innervated by the trigeminal motor nucleus is affected by inadequacies in the occlusion of the teeth that cause changes in posture and movement of the mandible. Reptile to mammal evolution shows that stomatognathic structures underwent changes related to mastication. Among several changes, there was the appearance of a new articulation between the mandible and skull: the temporomandibular joint. The bones of the old reptile joint, quadrate-articular, have detached from the mandible and are part of the middle ear bone chain. The former becomes the incus and the latter the malleus. This bone change also carried the tensor tympani and its trigeminal motor innervation. Inadequate occlusal contacts give rise to an adapted function of the mandible and the most common compensatory muscular response is hypertonia involving all mandibular muscles, including the tensor tympani. A fundamental clinical feature that demonstrates the involvement of the trigeminal fusimotor system is the characteristic pain by palpation, but no pain on the mandibular movement. Muscle pain is always felt in the dermatome innervated by the mandibular branch of the trigeminal nerve, which carries the motor fibers, reported as tightening, similar to cramp, and has regular behavior in intensity, duration and frequency. In addition, the patient has increased musculature volume, detected by palpation of certain anatomical landmarks, but with loss of functional efficiency. The neuromotor control of the mandibular movements is poor and when asked to make lateral jaw movement touching the teeth, it is common to observe that the patient moves the lips, eyes, and even turns the head in the same direction as the movement. There is also difficulty eating hard foods and talking fast. Tongue biting while chewing is frequent, meaning that these non-physiological events surpass protective reflex circuits. The report of ear pain, tinnitus, blocked ear sensation and sudden hearing loss is common in such patients, compatible with the tonic contraction of the tensor tympani. The fusimotor system hypothesis is able to explain all events related to the symptoms and helps to establish a correct diagnosis for certain types of hearing disorders.


Assuntos
Oclusão Dentária , Transtornos da Articulação Temporomandibular/complicações , Articulação Temporomandibular/fisiopatologia , Zumbido/etiologia , Evolução Biológica , Humanos , Hipercinese , Mandíbula/fisiopatologia , Mastigação , Modelos Teóricos , Movimento , Músculo Temporal/patologia , Tensor de Tímpano , Dente/fisiopatologia , Núcleo Motor do Nervo Trigêmeo
6.
Brain Struct Funct ; 224(8): 2823-2838, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31435738

RESUMO

Functional imaging of the brainstem may open new avenues for clinical diagnostics. However, for reliable assessments of brainstem activation, further efforts improving signal quality are needed. Six healthy subjects performed four repeated functional magnetic resonance imaging (fMRI) sessions on different days with jaw clenching as a motor task to elicit activation in the trigeminal motor nucleus. Functional images were acquired with a 7 T MR scanner using an optimized multiband EPI sequence. Activation measures in the trigeminal nucleus and a control region were assessed using different physiological noise correction methods (aCompCor and RETROICOR-based approaches with variable numbers of regressors) combined with cerebrospinal fluid or brainstem masking. Receiver-operating characteristic analyses accounting for sensitivity and specificity, activation overlap analyses to estimate the reproducibility between sessions, and intraclass correlation analyses (ICC) for testing reliability between subjects and sessions were used to systematically compare the physiological noise correction approaches. Masking the brainstem led to increased activation in the target ROI and resulted in higher values for the area under the curve (AUC) as a combined measure for sensitivity and specificity. With the highest values for AUC, activation overlap, and ICC, the most favorable physiological noise correction method was to control for the cerebrospinal fluid time series (aCompCor with one regressor). Brainstem motor nuclei activation can be reliably identified using high-field fMRI with optimized acquisition and processing strategies-even on single-subject level. Applying specific physiological noise correction methods improves reproducibility and reliability of brainstem activation encouraging future clinical applications.


Assuntos
Mapeamento Encefálico/métodos , Atividade Motora , Núcleo Motor do Nervo Trigêmeo/fisiologia , Adulto , Artefatos , Feminino , Humanos , Aumento da Imagem , Arcada Osseodentária , Imageamento por Ressonância Magnética , Masculino , Curva ROC , Reprodutibilidade dos Testes , Razão Sinal-Ruído
7.
J Comp Neurol ; 527(16): 2703-2729, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30980526

RESUMO

The highly mobile chin appendage of Gnathonemus petersii, the Schnauzenorgan, is used to actively probe the environment and is known to be a fovea of the electrosensory system. It receives an important innervation from both the trigeminal sensory and motor systems. However, little is known about the premotor control pathways that coordinate the movements of the Schnauzenorgan, or about central pathways originating from the trigeminal motor nucleus. The present study focuses on the central connections of the trigeminal motor system to elucidate premotor centers controlling Schnauzenorgan movements, with particular interest in the possible connections between the electrosensory and trigeminal systems. Neurotracer injections into the trigeminal motor nucleus revealed bilateral, reciprocal connections between the two trigeminal motor nuclei and between the trigeminal sensory and motor nuclei by bilateral labeling of cells and terminals. Prominent afferent input to the trigeminal motor nucleus originates from the nucleus lateralis valvulae, the nucleus dorsalis mesencephali, the cerebellar corpus C1, the reticular formation, and the Raphe nuclei. Retrogradely labeled cells were also observed in the central pretectal nucleus, the dorsal anterior pretectal nucleus, the tectum, the ventroposterior nucleus of the torus semicircularis, the gustatory sensory and motor nuclei, and in the hypothalamus. Labeled terminals, but not cell bodies, were observed in the nucleus lateralis valvulae and the reticular formation. No direct connections were found between the electrosensory system and the V motor nucleus but the central connections identified would provide several multisynaptic pathways linking these two systems, including possible efference copy and corollary discharge mechanisms.


Assuntos
Peixe Elétrico/anatomia & histologia , Núcleo Motor do Nervo Trigêmeo/citologia , Vias Aferentes/citologia , Animais , Cerebelo/citologia , Vias Eferentes/citologia , Interneurônios/citologia , Técnicas de Rastreamento Neuroanatômico , Nervo Trigêmeo/citologia
8.
Sci Rep ; 9(1): 799, 2019 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-30692571

RESUMO

The most recent research concerning amyotrophic lateral sclerosis (ALS) emphasizes the role of glia in disease development. Thus, one can suspect that the effective therapeutic strategy in treatment of ALS would be replacement of defective glia. One of the basic problems with human glial progenitors (hGRPs) replacement strategies is the time needed for the cells to become fully functional in vivo. The lifespan of most popular high copy number SOD1 mutant mice might be too short to acknowledge benefits of transplanted cells. We focused on developing immunodeficient rag2-/- model of ALS with lower number of transgene copies and longer lifespan. The obtained hSOD1/rag2 double mutant mice have been characterized. QPCR analysis revealed that copy number of hSOD1 transgene varied in our colony (4-8 copies). The difference in transgene copy number may be translated to significant impact on the lifespan. The death of long- and short-living hSOD1/rag2 mice is preceded by muscular weakness as early as one month before death. Importantly, based on magnetic resonance imaging we identified that mutant mice demonstrated abnormalities within the medullar motor nuclei. To conclude, we developed long-living double mutant hSOD1/rag2 mice, which could be a promising model for testing therapeutic utility of human stem cells.


Assuntos
Esclerose Amiotrófica Lateral/diagnóstico por imagem , Variações do Número de Cópias de DNA , Proteínas de Ligação a DNA/genética , Superóxido Dismutase-1/genética , Esclerose Amiotrófica Lateral/genética , Esclerose Amiotrófica Lateral/imunologia , Esclerose Amiotrófica Lateral/fisiopatologia , Animais , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Feminino , Técnicas de Inativação de Genes , Humanos , Hospedeiro Imunocomprometido , Masculino , Camundongos , Camundongos Transgênicos , Dobramento de Proteína , Índice de Gravidade de Doença , Medula Espinal/diagnóstico por imagem , Medula Espinal/metabolismo , Superóxido Dismutase-1/química , Superóxido Dismutase-1/metabolismo , Núcleo Motor do Nervo Trigêmeo/diagnóstico por imagem , Núcleo Motor do Nervo Trigêmeo/metabolismo
9.
Invest Ophthalmol Vis Sci ; 59(12): 5201-5209, 2018 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-30372748

RESUMO

Purpose: Proper control of eye movements is critical to vision, but relatively little is known about the molecular mechanisms that regulate development and axon guidance in the ocular motor system or cause the abnormal innervation patterns (oculomotor synkinesis) seen in developmental disorders and after oculomotor nerve palsy. We developed an ex vivo slice assay that allows for live imaging and molecular manipulation of the growing oculomotor nerve, which we used to identify axon guidance cues that affect the oculomotor nerve. Methods: Ex vivo slices were generated from E10.5 IslMN-GFP embryos and grown for 24 to 72 hours. To assess for CXCR4 function, the specific inhibitor AMD3100 was added to the culture media. Cxcr4cko/cko:Isl-Cre:ISLMN-GFP and Cxcl12KO/KO:ISLMN-GFP embryos were cleared and imaged on a confocal microscope. Results: When AMD3100 was added to the slice cultures, oculomotor axons grew dorsally (away from the eye) rather than ventrally (toward the eye). Axons that had already exited the midbrain continued toward the eye. Loss of Cxcr4 or Cxcl12 in vivo caused misrouting of the oculomotor nerve dorsally and motor axons from the trigeminal motor nerve, which normally innervate the muscles of mastication, aberrantly innervated extraocular muscles in the orbit. This represents the first mouse model of trigeminal-oculomotor synkinesis. Conclusions: CXCR4/CXCL12 signaling is critical for the initial pathfinding decisions of oculomotor axons and their proper exit from the midbrain. Failure of the oculomotor nerve to innervate its extraocular muscle targets leads to aberrant innervation by other motor neurons, indicating that muscles lacking innervation may secrete cues that attract motor axons.


Assuntos
Quimiocina CXCL12/fisiologia , Doenças do Nervo Oculomotor/fisiopatologia , Nervo Oculomotor/anormalidades , Receptores CXCR4/fisiologia , Transdução de Sinais/fisiologia , Sincinesia/fisiopatologia , Núcleo Motor do Nervo Trigêmeo/fisiopatologia , Animais , Fármacos Anti-HIV/farmacologia , Axônios/patologia , Benzilaminas , Ciclamos , Proteínas de Fluorescência Verde/metabolismo , Compostos Heterocíclicos/farmacologia , Imuno-Histoquímica , Hibridização In Situ , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Músculos Oculomotores/inervação , Nervo Oculomotor/efeitos dos fármacos , Técnicas de Cultura de Órgãos
10.
Sheng Li Xue Bao ; 70(1): 9-16, 2018 Feb 25.
Artigo em Chinês | MEDLINE | ID: mdl-29492509

RESUMO

To observe the plasticity changes of trigeminal motor nucleus (Mo5) and masseter H-reflex in unilateral mastication model rats and explore the possible mechanism of functional plasticity in motor center involved in unilateral mastication, 54 adult male Wistar rats were randomly divided into 1-month (n = 10), 3-month (n = 10), and 16-month (n = 7) model groups and their corresponding control groups, respectively. Unilateral mastication model rats were prepared by intermittent removal of clinical crowns of left teeth (model side). Rats were anesthetized (20% urethane, i.p.), and bilateral Mo5 were chosen to conduct extracellular recordings, while bilateral electromyography (EMG) of masseter muscle and its H-reflex were simultaneously recorded by a polygraph. It was observed that the firing rate of Mo5 neurons in model sides was significantly lower than that of right sides in 3 model groups, and that of left sides in their control groups. The response latency of Mo5, which was evoked by electrical stimulation of masseter nerve in model sides of 1-month and 3-month model groups, was significantly longer than that of left sides in their control groups. Moreover, the amplitude of H-wave in model sides of 3-month and 16-month model groups was lower than that of left sides in their control groups when H-reflex was evoked by electrical stimulation of left masseter nerve. These results suggest that unilateral mastication in model rats decreases the Mo5 neuron excitability, and this may be one of the functional plasticity mechanisms in motor center involved in unilateral mastication.


Assuntos
Músculo Masseter/fisiologia , Mastigação , Plasticidade Neuronal , Núcleo Motor do Nervo Trigêmeo/fisiologia , Animais , Estimulação Elétrica , Eletromiografia , Masculino , Neurônios Motores , Ratos , Ratos Wistar
11.
Brain Struct Funct ; 223(5): 2259-2268, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29460053

RESUMO

The neurons in the trigeminal mesencephalic nucleus (Vmes) innervate jaw-closing muscle spindles and periodontal ligaments, and play a crucial role in the regulation of jaw movements. Recently, it was shown that many boutons that form synapses on them are immunopositive for glycine (Gly+), suggesting that these neurons receive glycinergic input. Information about the glycine receptors that mediate this input is needed to help understand the role of glycine in controlling Vmes neuron excitability. For this, we investigated the expression of glycine receptor subunit alpha 3 (GlyRα3) and gephyrin in neurons in Vmes and the trigeminal motor nucleus (Vmo), and the Gly+ boutons that contact them by light- and electron-microscopic immunocytochemistry and quantitative ultrastructural analysis. The somata of the Vmes neurons were immunostained for GlyRα3, but not gephyrin, indicating expression of homomeric GlyR. The immunostaining for GlyRα3 was localized away from the synapses in the Vmes neuron somata, in contrast to the Vmo neurons, where the staining for GlyRα3 and gephyrin were localized at the subsynaptic zones in somata and dendrites. Additionally, the ultrastructural determinants of synaptic strength, bouton volume, mitochondrial volume, and active zone area, were significantly smaller in Gly+ boutons on the Vmes neurons than in those on the Vmo neurons. These findings support the notion that the Vmes neurons receive glycinergic input via putative extrasynaptic homomeric glycine receptors, likely mediating a slow, tonic modulation of the Vmes neuron excitability.


Assuntos
Neurônios/metabolismo , Terminações Pré-Sinápticas/metabolismo , Receptores de Glicina/metabolismo , Núcleo Motor do Nervo Trigêmeo/citologia , Animais , Proteínas de Transporte/metabolismo , Proteínas de Transporte/ultraestrutura , Dendritos/ultraestrutura , Masculino , Proteínas de Membrana/metabolismo , Proteínas de Membrana/ultraestrutura , Microscopia Confocal , Microscopia Imunoeletrônica , Neurônios/ultraestrutura , Terminações Pré-Sinápticas/ultraestrutura , Ratos , Ratos Sprague-Dawley , Receptores de Glicina/ultraestrutura , Núcleo Motor do Nervo Trigêmeo/diagnóstico por imagem
12.
Neurochem Int ; 119: 159-170, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29061384

RESUMO

Dystonia musculorum (dt) mice, which have a mutation in the Dystonin (Dst) gene, are used as animal models to investigate the human disease known as hereditary sensory and autonomic neuropathy type VI. Massive neuronal cell death is observed, mainly in the peripheral nervous system (PNS) of dt mice. We and others have recently reported a histopathological feature of these mice that neurofilament (NF) accumulates in various areas of the central nervous system (CNS), including motor pathways. Although dt mice show motor disorder and growth retardation, the causes for these are still unknown. Here we performed histopathological analyses on motor units of the trigeminal motor nucleus (Mo5 nucleus), because they are a good system to understand neuronal responses in the mutant CNS, and abnormalities in this system may lead to problems in mastication, with subsequent growth retardation. We report that motoneurons with NF accumulation in the Mo5 nuclei of DstGt homozygous mice express the stress-induced genes CHOP, ATF3, and lipocalin 2 (Lcn2). We also show a reduced number of Mo5 motoneurons and a reduced size of Mo5 nuclei in DstGt homozygous mice, possibly due to apoptosis, given the presence of cleaved caspase 3-positive Mo5 motoneurons. In the mandibular (V3) branches of the trigeminal nerve, which contains axons of Mo5 motoneurons and trigeminal sensory neurons, there was infiltration of Iba1-positive macrophages. Finally, we report atrophy of the masseter muscles in DstGt homozygous mice, which showed abnormal nuclear localization of myofibrils and increased expression of atrogin-1 mRNA, a muscle atrophy-related gene and weaker masseter muscle strength with uncontrolled muscle activity by electromyography (EMG). Taken together, our findings strongly suggest that mastication in dt mice is affected due to abnormalities of Mo5 motoneurons and masseter muscles, leading to growth retardation at the post-weaning stages.


Assuntos
Axônios/metabolismo , Distonia/metabolismo , Músculo Masseter/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Núcleo Motor do Nervo Trigêmeo/metabolismo , Animais , Proteínas de Transporte/metabolismo , Proteínas do Citoesqueleto/metabolismo , Camundongos Transgênicos , Neurônios Motores/metabolismo , Células Receptoras Sensoriais/metabolismo
13.
Neuroscience ; 358: 211-226, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28673717

RESUMO

Phox2b encodes a paired-like homeodomain-containing transcription factor essential for development of the autonomic nervous system. Phox2b-expressing (Phox2b+) neurons are present in the reticular formation dorsal to the trigeminal motor nucleus (RdV) as well as the nucleus of the solitary tract and parafacial respiratory group. However, the nature of Phox2b+ RdV neurons is still unclear. We investigated the physiological and morphological properties of Phox2b+ RdV neurons using postnatal day 2-7 transgenic rats expressing yellow fluorescent protein under the control of Phox2b. Almost all of Phox2b+ RdV neurons were glutamatergic, whereas Phox2b-negative (Phox2b-) RdV neurons consisted of a few glutamatergic, many GABAergic, and many glycinergic neurons. The majority (48/56) of Phox2b+ neurons showed low-frequency firing (LF), while most of Phox2b- neurons (35/42) exhibited high-frequency firing (HF) in response to intracellularly injected currents. All, but one, Phox2b+ neurons (55/56) did not fire spontaneously, whereas three-fourths of the Phox2b- neurons (31/42) were spontaneously active. K+ channel and persistent Na+ current blockers affected the firing of LF and HF neurons. The majority of Phox2b+ (35/46) and half of the Phox2b- neurons (19/40) did not respond to stimulations of the mesencephalic trigeminal nucleus, the trigeminal tract, and the principal sensory trigeminal nucleus. Biocytin labeling revealed that about half of the Phox2b+ (5/12) and Phox2b- RdV neurons (5/10) send their axons to the trigeminal motor nucleus. These results suggest that Phox2b+ RdV neurons have distinct neurotransmitter phenotypes and firing properties from Phox2b- RdV neurons and might play important roles in feeding-related functions including suckling and possibly mastication.


Assuntos
Proteínas de Homeodomínio/metabolismo , Vias Neurais/fisiologia , Neurônios/metabolismo , Formação Reticular/citologia , Fatores de Transcrição/metabolismo , Núcleo Motor do Nervo Trigêmeo/citologia , Potenciais de Ação/fisiologia , Animais , Animais Recém-Nascidos , Regulação da Expressão Gênica no Desenvolvimento/genética , Glutamato Descarboxilase/metabolismo , Proteínas da Membrana Plasmática de Transporte de Glicina/metabolismo , Proteínas de Homeodomínio/genética , Técnicas In Vitro , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Lisina/análogos & derivados , Lisina/metabolismo , Técnicas de Patch-Clamp , Ratos , Ratos Transgênicos , Fatores de Transcrição/genética , Proteína Vesicular 2 de Transporte de Glutamato/metabolismo
14.
J Neurophysiol ; 118(2): 1082-1091, 2017 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-28539391

RESUMO

We examined the reflex response of the human masseter muscle to electrical stimulation of the lip using both single motor unit and surface electromyogram based methods. Using the classical analysis methods, reflex response to mild electrical stimuli generated two distinct short-lasting inhibitions. This pattern may reflect the development of combinations of short- and long-latency inhibitory postsynaptic potentials as a result of the mildly painful electrical lip stimulation. However, this pattern appearing in the classical analysis methods may have developed as a consequence of earlier responses and may not be genuine. This study examined the genuineness of these responses using both the classical analysis methods and the discharge rate method to uncover the realistic postsynaptic potentials in human trigeminal motor nucleus. Using the discharge rate method, we found that the electrical lip stimulation only generated a long-lasting single or compound inhibitory response that is followed by late, long-lasting excitation. These findings have important implications on the redrawing of the neuronal pathways of the trigeminal nerve that are frequently used to judge neuromuscular disorders of the trigeminal region.NEW & NOTEWORTHY We examined the human masseter reflex response to electrical stimulation of lower lip to uncover realistic postsynaptic potentials in the trigeminal motor nucleus. We found that the stimulation generates a long-lasting single or compound inhibitory response that is followed by a late, long-lasting excitation. These findings have important implications on the redrawing of the neuronal pathways of the trigeminal nerve that are frequently used to judge neuromuscular disorders of the trigeminal region.


Assuntos
Lábio/fisiologia , Músculo Masseter/fisiologia , Neurônios Motores/fisiologia , Reflexo , Núcleo Motor do Nervo Trigêmeo/fisiologia , Adulto , Estimulação Elétrica , Eletromiografia , Humanos , Lábio/inervação , Adulto Jovem
15.
Brain Struct Funct ; 222(7): 3231-3239, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28326439

RESUMO

Gamma-motoneurons (γMNs) play a crucial role in regulating isometric muscle contraction. The slow jaw-closing during mastication is one of the most functional isometric contractions, which is developed by the rank-order recruitment of alpha-motoneurons (αMNs) in a manner that reflects the size distribution of αMNs. In a mouse spinal motor nucleus, there are two populations of small and large MNs; the former was identified as a population of γMNs based on the positive expression of the transcription factor estrogen-related receptor 3 (Err3) and negative expression of the neuronal DNA-binding protein NeuN, and the latter as that of αMNs based on the opposite pattern of immunoreactivity. However, the differential identification of αMNs and γMNs in the trigeminal motor nucleus (TMN) remains an assumption based on the size of cell bodies that were retrogradely stained with HRP. We here examined the size distributions of αMNs and γMNs in the dorsolateral TMN (dl-TMN) by performing immunohistochemistry using anti-Err3 and anti-NeuN antibodies. The dl-TMN was identified by immunopositivity for vesicular glutamate transporter-1. Immunostaining for choline acetyltransferase and Err3/NeuN revealed that the dl-TMN is composed of 65% αMNs and 35% γMNs. The size distribution of αMNs was bimodal, while that of γMNs was almost the same as that of the population of small αMNs, suggesting the presence of αMNs as small as γMNs. Consistent with the size concept of motor units, the presence of smaller jaw-closing αMNs was coherent with the inclusion of jaw-closing muscle fibers with smaller diameters compared to limb muscle fibers.


Assuntos
Neurônios Motores/classificação , Neurônios Motores/fisiologia , Núcleo Motor do Nervo Trigêmeo/citologia , Animais , Contagem de Células/métodos , Colina O-Acetiltransferase/metabolismo , Transportador de Glucose Tipo 1/metabolismo , Masculino , Fosfopiruvato Hidratase/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de Estrogênio/metabolismo , Proteína Vesicular 1 de Transporte de Glutamato/metabolismo
16.
Brain Struct Funct ; 222(7): 3163-3178, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28299422

RESUMO

Muscle tone is regulated across sleep-wake states, being maximal in waking, reduced in slow wave sleep (SWS) and absent in paradoxical or REM sleep (PS or REMS). Such changes in tone have been recorded in the masseter muscles and shown to correspond to changes in activity and polarization of the trigeminal motor 5 (Mo5) neurons. The muscle hypotonia and atonia during sleep depend in part on GABA acting upon both GABAA and GABAB receptors (Rs) and acetylcholine (ACh) acting upon muscarinic 2 (AChM2) Rs. Here, we examined whether Mo5 neurons undergo homeostatic regulation through changes in these inhibitory receptors following prolonged activity with enforced waking. By immunofluorescence, we assessed that the proportion of Mo5 neurons positively stained for GABAARs was significantly higher after sleep deprivation (SD, ~65%) than sleep control (SC, ~32%) and that the luminance of the GABAAR fluorescence was significantly higher after SD than SC and sleep recovery (SR). Although, all Mo5 neurons were positively stained for GABABRs and AChM2Rs (100%) in all groups, the luminance of these receptors was significantly higher following SD as compared to SC and SR. We conclude that the density of GABAA, GABAB and AChM2 receptors increases on Mo5 neurons during SD. The increase in these receptors would be associated with increased inhibition in the presence of GABA and ACh and thus a homeostatic down-scaling in the excitability of the Mo5 neurons after prolonged waking and resulting increased susceptibility to muscle hypotonia or atonia along with sleep.


Assuntos
Homeostase/fisiologia , Neurônios Motores/fisiologia , Receptores de GABA/metabolismo , Receptores Muscarínicos/metabolismo , Privação do Sono/patologia , Núcleo Motor do Nervo Trigêmeo/patologia , Acetilcolina/metabolismo , Animais , Contagem de Células , Eletroencefalografia , Regulação da Expressão Gênica/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fatores de Tempo , Vigília/fisiologia , Ácido gama-Aminobutírico/metabolismo
17.
Sci Rep ; 6: 36491, 2016 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-27819291

RESUMO

LIM-homeodomain (HD) transcription factors form a multimeric complex and assign neuronal subtype identities, as demonstrated by the hexameric ISL1-LHX3 complex which gives rise to somatic motor (SM) neurons. However, the roles of combinatorial LIM code in motor neuron diversification and their subsequent differentiation is much less well understood. In the present study, we demonstrate that the ISL1 controls postmitotic cranial branchiomotor (BM) neurons including the positioning of the cell bodies and peripheral axon pathfinding. Unlike SM neurons, which transform into interneurons, BM neurons are normal in number and in marker expression in Isl1 mutant mice. Nevertheless, the movement of trigeminal and facial BM somata is stalled, and their peripheral axons are fewer or misrouted, with ectopic branches. Among genes whose expression level changes in previous ChIP-seq and microarray analyses in Isl1-deficient cell lines, we found that Slit2 transcript was almost absent from BM neurons of Isl1 mutants. Both ISL1-LHX3 and ISL1-LHX4 bound to the Slit2 enhancer and drove endogenous Slit2 expression in SM and BM neurons. Our findings suggest that combinations of ISL1 and LHX factors establish cell-type specificity and functional diversity in terms of motor neuron identities and/or axon development.


Assuntos
Peptídeos e Proteínas de Sinalização Intercelular/genética , Proteínas com Homeodomínio LIM/genética , Neurônios Motores/fisiologia , Proteínas do Tecido Nervoso/genética , Neurogênese/genética , Fatores de Transcrição/genética , Animais , Axônios/fisiologia , Diferenciação Celular/genética , Regulação da Expressão Gênica no Desenvolvimento/genética , Interneurônios/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Transcrição Genética/genética , Núcleo Motor do Nervo Trigêmeo/fisiologia
18.
Neuroreport ; 27(17): 1274-1280, 2016 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-27755281

RESUMO

Cell bodies of trigeminal mesencephalic nucleus (Vmes) neurons are located within the central nervous system, and therefore, peripheral as well as central acidosis can modulate the excitability of Vmes neurons. Here, we report the effect of acidic pH on voltage-gated Na channels in acutely isolated rat Vmes neurons using a conventional whole-cell patch clamp technique. Acidic pH (pH 6.0) slightly but significantly shifted both the activation and steady-state fast inactivation relationships toward depolarized potentials. However, acidic pH (pH 6.0) had a minor effect on the inactivation kinetics of voltage-gated Na channels. Less sensitivity of voltage-gated Na channels to acidic pH may allow Vmes neurons to transduce the precise proprioceptive information even under acidic pH conditions.


Assuntos
Ácidos , Potenciais da Membrana/fisiologia , Neurônios/fisiologia , Canais de Sódio/fisiologia , Núcleo Motor do Nervo Trigêmeo/citologia , Animais , Animais Recém-Nascidos , Biofísica , Cloreto de Cádmio/farmacologia , Bloqueadores dos Canais de Cálcio/farmacologia , Células Cultivadas , Estimulação Elétrica , Concentração de Íons de Hidrogênio , Potenciais da Membrana/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Bloqueadores dos Canais de Sódio/farmacologia , Canais de Sódio/metabolismo , Tetrodotoxina/farmacologia
19.
eNeuro ; 3(3)2016.
Artigo em Inglês | MEDLINE | ID: mdl-27482536

RESUMO

Because a rank-ordered recruitment of motor units occurs during isometric contraction of jaw-closing muscles, jaw-closing motoneurons (MNs) may be recruited in a manner dependent on their soma sizes or input resistances (IRs). In the dorsolateral part of the trigeminal motor nucleus (dl-TMN) in rats, MNs abundantly express TWIK (two-pore domain weak inwardly rectifying K channel)-related acid-sensitive-K(+) channel (TASK)-1 and TASK3 channels, which determine the IR and resting membrane potential. Here we examined how TASK channels are involved in IR-dependent activation/recruitment of MNs in the rat dl-TMN by using multiple methods. The real-time PCR study revealed that single large MNs (>35 µm) expressed TASK1 and TASK3 mRNAs more abundantly compared with single small MNs (15-20 µm). The immunohistochemistry revealed that TASK1 and TASK3 channels were complementarily distributed in somata and dendrites of MNs, respectively. The density of TASK1 channels seemed to increase with a decrease in soma diameter while there were inverse relationships between the soma size of MNs and IR, resting membrane potential, or spike threshold. Dual whole-cell recordings obtained from smaller and larger MNs revealed that the recruitment of MNs depends on their IRs in response to repetitive stimulation of the presumed Ia afferents. 8-Bromoguanosine-cGMP decreased IRs in small MNs, while it hardly changed those in large MNs, and subsequently decreased the difference in spike-onset latency between the smaller and larger MNs, causing a synchronous activation of MNs. These results suggest that TASK channels play critical roles in rank-ordered recruitment of MNs in the dl-TMN.


Assuntos
Neurônios Motores/metabolismo , Canais de Potássio de Domínios Poros em Tandem/metabolismo , Canais de Potássio/metabolismo , Núcleo Motor do Nervo Trigêmeo/metabolismo , Animais , Tamanho Celular , GMP Cíclico/metabolismo , Dendritos/metabolismo , Feminino , Células HEK293 , Humanos , Masculino , Potenciais da Membrana/fisiologia , Camundongos , Neurônios Motores/citologia , Proteínas do Tecido Nervoso , Oócitos , Canais de Potássio/genética , Canais de Potássio de Domínios Poros em Tandem/genética , RNA Mensageiro/metabolismo , Ratos Wistar , Técnicas de Cultura de Tecidos , Núcleo Motor do Nervo Trigêmeo/citologia , Xenopus laevis
20.
J Comp Neurol ; 524(4): 738-58, 2016 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-26224546

RESUMO

Neurons in the trigeminal (Mo5), facial (Mo7), ambiguus (Amb), and hypoglossal (Mo12) motor nuclei innervate jaw, facial, pharynx/larynx/esophagus, and tongue muscles, respectively. They are essential for movements subserving feeding, exploration of the environment, and social communication. These neurons are largely controlled by sensory afferents and premotor neurons of the reticular formation, where central pattern generator circuits controlling orofacial movements are located. To provide a description of the orofacial nuclei of the adult mouse and to ascertain the influence of excitatory and inhibitory afferents upon them, we used stereology to estimate the number of motoneurons as well as of varicosities immunopositive for glutamate (VGluT1+, VGluT2+) and GABA/glycine (known as VIAAT+ or VGAT+) vesicular transporters in the Mo5, Mo7, Amb, and Mo12. Mo5, Mo7, Amb, and Mo12 contain ∼1,000, ∼3,000, ∼600, and ∼1,700 cells, respectively. VGluT1+, VGluT2+, and VIAAT+ varicosities respectively represent: 28%, 41%, and 31% in Mo5; 2%, 49%, and 49% in Mo7; 12%, 42%, and 46% in Amb; and 4%, 54%, and 42% in Mo12. The Mo5 jaw-closing subdivision shows the highest VGluT1+ innervation. Noticeably, the VGluT2+ and VIAAT+ varicosity density in Mo7 is 5-fold higher than in Mo5 and 10-fold higher than in Amb and Mo12. The high density of terminals in Mo7 likely reflects the convergence and integration of numerous inputs to motoneurons subserving the wide range of complex behaviors to which this nucleus contributes. Also, somatic versus neuropil location of varicosities suggests that most of these afferents are integrated in the dendritic trees of Mo7 neurons.


Assuntos
Face/inervação , Núcleo do Nervo Facial/citologia , Bulbo/citologia , Neurônios Motores/citologia , Boca/inervação , Núcleo Motor do Nervo Trigêmeo/citologia , Animais , Contagem de Células , Núcleo do Nervo Facial/metabolismo , Ácido Glutâmico/metabolismo , Glicina/metabolismo , Nervo Hipoglosso/citologia , Nervo Hipoglosso/metabolismo , Imuno-Histoquímica , Masculino , Bulbo/metabolismo , Camundongos Endogâmicos C57BL , Neurônios Motores/metabolismo , Inibição Neural/fisiologia , Tamanho do Órgão , Núcleo Motor do Nervo Trigêmeo/metabolismo , Proteínas de Transporte Vesicular/metabolismo , Ácido gama-Aminobutírico/metabolismo
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