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Mayadali ÜS, Chertes CAM, Sinicina I, Shaikh AG, Horn AKE. Ion channel profiles of extraocular motoneurons and internuclear neurons in human abducens and trochlear nuclei. Front Neuroanat 2024; 18:1411154. [PMID: 38957435 PMCID: PMC11217180 DOI: 10.3389/fnana.2024.1411154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Accepted: 05/27/2024] [Indexed: 07/04/2024] Open
Abstract
Introduction Extraocular muscles are innervated by two anatomically and histochemically distinct motoneuron populations: motoneurons of multiply-innervated fibers (MIF), and of singly-innervated fibers (SIF). Recently, it has been established by our research group that these motoneuron types of monkey abducens and trochlear nuclei express distinct ion channel profiles: SIF motoneurons, as well as abducens internuclear neurons (INT), express strong Kv1.1 and Kv3.1b immunoreactivity, indicating their fast-firing capacity, whereas MIF motoneurons do not. Moreover, low voltage activated cation channels, such as Cav3.1 and HCN1 showed differences between MIF and SIF motoneurons, indicating distinct post-inhibitory rebound characteristics. However, the ion channel profiles of MIF and SIF motoneurons have not been established in human brainstem tissue. Methods Therefore, we used immunohistochemical methods with antibodies against Kv, Cav3 and HCN channels to (1) examine the human trochlear nucleus in terms of anatomical organization of MIF and SIF motoneurons, (2) examine immunolabeling patterns of ion channel proteins in the distinct motoneurons populations in the trochlear and abducens nuclei. Results In the examination of the trochlear nucleus, a third motoneuron subgroup was consistently encountered with weak perineuronal nets (PN). The neurons of this subgroup had -on average- larger diameters than MIF motoneurons, and smaller diameters than SIF motoneurons, and PN expression strength correlated with neuronal size. Immunolabeling of various ion channels revealed that, in general, human MIF and SIF motoneurons did not differ consistently, as opposed to the findings in monkey trochlear and abducens nuclei. Kv1.1, Kv3.1b and HCN channels were found on both MIF and SIF motoneurons and the immunolabeling density varied for multiple ion channels. On the other hand, significant differences between SIF motoneurons and INTs were found in terms of HCN1 immunoreactivity. Discussion These results indicated that motoneurons may be more variable in human in terms of histochemical and biophysiological characteristics, than previously thought. This study therefore establishes grounds for any histochemical examination of motor nuclei controlling extraocular muscles in eye movement related pathologies in the human brainstem.
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Affiliation(s)
- Ümit S. Mayadali
- Chair of Vegetative Anatomy, Faculty of Medicine, Institute of Anatomy, LMU Munich, Munich, Germany
| | - Christina A. M. Chertes
- Chair of Vegetative Anatomy, Faculty of Medicine, Institute of Anatomy, LMU Munich, Munich, Germany
| | - Inga Sinicina
- Faculty of Medicine, Institute of Legal Medicine, LMU Munich, Munich, Germany
| | - Aasef G. Shaikh
- Department of Neurology, University Hospitals, Cleveland VA Medical Center, Case Western Reserve University, Cleveland, OH, United States
| | - Anja K. E. Horn
- Chair of Vegetative Anatomy, Faculty of Medicine, Institute of Anatomy, LMU Munich, Munich, Germany
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Hoh JFY. Developmental, Physiological and Phylogenetic Perspectives on the Expression and Regulation of Myosin Heavy Chains in Craniofacial Muscles. Int J Mol Sci 2024; 25:4546. [PMID: 38674131 PMCID: PMC11050549 DOI: 10.3390/ijms25084546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 04/15/2024] [Accepted: 04/18/2024] [Indexed: 04/28/2024] Open
Abstract
This review deals with the developmental origins of extraocular, jaw and laryngeal muscles, the expression, regulation and functional significance of sarcomeric myosin heavy chains (MyHCs) that they express and changes in MyHC expression during phylogeny. Myogenic progenitors from the mesoderm in the prechordal plate and branchial arches specify craniofacial muscle allotypes with different repertoires for MyHC expression. To cope with very complex eye movements, extraocular muscles (EOMs) express 11 MyHCs, ranging from the superfast extraocular MyHC to the slowest, non-muscle MyHC IIB (nmMyH IIB). They have distinct global and orbital layers, singly- and multiply-innervated fibres, longitudinal MyHC variations, and palisade endings that mediate axon reflexes. Jaw-closing muscles express the high-force masticatory MyHC and cardiac or limb MyHCs depending on the appropriateness for the acquisition and mastication of food. Laryngeal muscles express extraocular and limb muscle MyHCs but shift toward expressing slower MyHCs in large animals. During postnatal development, MyHC expression of craniofacial muscles is subject to neural and hormonal modulation. The primary and secondary myotubes of developing EOMs are postulated to induce, via different retrogradely transported neurotrophins, the rich diversity of neural impulse patterns that regulate the specific MyHCs that they express. Thyroid hormone shifts MyHC 2A toward 2B in jaw muscles, laryngeal muscles and possibly extraocular muscles. This review highlights the fact that the pattern of myosin expression in mammalian craniofacial muscles is principally influenced by the complex interplay of cell lineages, neural impulse patterns, thyroid and other hormones, functional demands and body mass. In these respects, craniofacial muscles are similar to limb muscles, but they differ radically in the types of cell lineage and the nature of their functional demands.
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Affiliation(s)
- Joseph Foon Yoong Hoh
- Discipline of Physiology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
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Hao J, Wang M, Liu J, Yusufu M, Cao K, Fu J. Alteration of Neurotrophic Factors and Innervation in Extraocular Muscles of Individuals With Concomitant Esotropia. Invest Ophthalmol Vis Sci 2024; 65:1. [PMID: 38441891 PMCID: PMC10916883 DOI: 10.1167/iovs.65.3.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 02/15/2024] [Indexed: 03/07/2024] Open
Abstract
Purpose To determine whether neurotrophic factors and innervation in extraocular muscles (EOMs) were altered in different types of concomitant esotropia, and to explore the possible association between neurotrophic factors and innervation of EOMs in humans. Methods Patients with concomitant esotropia who required strabismus surgery were recruited from January to December 2022. Lateral rectus EOMs were obtained from patients, and controls were obtained from deceased organ donors. Immunofluorescence (IF) was performed to detect innervation of EOMs (neurofilament and synaptophysin), and immunohistochemistry (IHC) was used to detect the neurotrophic factors insulin-like growth factor-1 (IGF-1), brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), and neurotrophin-3 (NT-3). The positive IHC results were further verified using western blotting (WB). One-way ANOVA followed by a Dunnett's multiple comparison post hoc test was used for continuous variables and the χ2 test for categorical variables. Spearman correlation analysis was used for the correlation analysis. Results We collected lateral rectus EOM samples from acute and chronic types of concomitant esotropia and controls. Consistent with IHC, WB showed that IGF-1 was significantly increased in patients with acute acquired comitant esotropia or essential infantile esotropia compared with controls. In IF, synaptophysins were significantly increased only in acute acquired comitant esotropia compared with controls. Furthermore, Spearman correlation analysis showed that the correlation between IGF-1 and synaptophysin was borderline (P = 0.057) for patients with acute acquired comitant esotropia. Conclusions Our study highlights the role of IGF-1 and altered innervation of EOMs in acute acquired comitant esotropia, suggesting that an effect of increased IGF-1 on nerve innervation may temporarily cause a compensatory increase in the strength of lateral rectus muscles.
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Affiliation(s)
- Jie Hao
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Beijing Key Laboratory of Ophthalmology & Visual Sciences, Beijing, China
| | - Meixu Wang
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Beijing Key Laboratory of Ophthalmology & Visual Sciences, Beijing, China
| | - Jiawen Liu
- Industrial Engineering and Operations Research, University of California, Berkeley, California, United States
| | - Mayinuer Yusufu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
- Department of Surgery (Ophthalmology), The University of Melbourne, Melbourne, Australia
| | - Kai Cao
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Beijing Key Laboratory of Ophthalmology & Visual Sciences, Beijing, China
| | - Jing Fu
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- Beijing Key Laboratory of Ophthalmology & Visual Sciences, Beijing, China
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Venugopal S, Ghulam-Jhelani Z, Ahn IS, Yang X, Wiedau M, Simmons D, Chandler SH. Early deficits in GABA inhibition parallels an increase in L-type Ca 2+ currents in the jaw motor neurons of SOD1 G93A mouse model for ALS. Neurobiol Dis 2023; 177:105992. [PMID: 36623607 DOI: 10.1016/j.nbd.2023.105992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 12/21/2022] [Accepted: 01/05/2023] [Indexed: 01/09/2023] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) involves protracted pre-symptomatic periods of abnormal motor neuron (MN) excitability occurring in parallel with central and peripheral synaptic perturbations. Focusing on inhibitory control of MNs, we first compared longitudinal changes in pre-synaptic terminal proteins for GABA and glycine neurotransmitters around the soma of retrogradely identified trigeminal jaw closer (JC) MNs and ChAT-labeled midbrain extraocular (EO) MNs in the SOD1G93A mouse model for ALS. Fluorescence immunocytochemistry and confocal imaging were used to quantify GAD67 and GlyT2 synaptic bouton density (SBD) around MN soma at pre-symptomatic ages ∼P12 (postnatal), ∼P50 (adult) and near disease end-stage (∼P135) in SOD1G93A mice and age-matched wild-type (WT) controls. We noted reduced GAD67 innervation in the SOD1G93A trigeminal jaw closer MNs around P12, relative to age-matched WT and no significant difference around P50 and P135. In contrast, both GAD67 and GlyT2 innervation were elevated in the SOD1G93A EO MNs at the pre-symptomatic time points. Considering trigeminal MNs are vulnerable in ALS while EO MNs are spared, we suggest that upregulation of inhibition in the latter might be compensatory. Notable contrast also existed in the innate co-expression patterns of GAD67 and GlyT2 with higher mutual information (co-dependency) in EO MNs compared to JC in both SOD1G93A and WT mice, especially at adult stages (P50 and P135). Around P12 when GAD67 terminals expression was low in the mutant, we further tested for persistent GABA inhibition in those MNs using in vitro patch-clamp electrophysiology. Our results show that SOD1G93A JC MNs have reduced persistent GABA inhibition, relative to WT. Pharmacological blocking of an underlying tonically active GABA conductance using the GABA-α5 subunit inverse agonist, L-655-708, disinhibited WT JC MNs and lowered their recruitment threshold, suggesting its role in the control of intrinsic MN excitability. Quantitative RT-PCR in laser dissected JC MNs further supported a reduction in GABA-α5 subunit mRNA expression in the mutant. In light of our previous report that JC MNs forming putative fast motor units have lower input threshold in the SOD1G93A mice, we suggest that our present result on reduced GABA-α5 tonic inhibition provides for a mechanism contributing to such imbalance. In parallel with reduced GABA inhibition, we noted an increase in voltage-gated L-type Ca2+ currents in the mutant JC MNs around P12. Together these results support that, early modifications in intrinsic properties of vulnerable MNs could be an adaptive response to counter synaptic deficits.
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Affiliation(s)
- Sharmila Venugopal
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Neurology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Zohal Ghulam-Jhelani
- Undergraduate Interdepartmental Program for Neuroscience, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - In Sook Ahn
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Xia Yang
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Martina Wiedau
- Department of Neurology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Dwayne Simmons
- Department of Biology, Baylor University, Waco, TX 76798, USA
| | - Scott H Chandler
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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Ding Y, Botchway BOA, Zhang Y, Jin T, Liu X. The combination of autologous mesenchymal stem cell-derived exosomes and neurotrophic factors as an intervention for amyotrophic lateral sclerosis. Ann Anat 2022; 242:151921. [PMID: 35278658 DOI: 10.1016/j.aanat.2022.151921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 02/19/2022] [Accepted: 02/24/2022] [Indexed: 10/18/2022]
Abstract
Amyotrophic lateral sclerosis is a chronic progressive degeneration of motor neurons and has a high mortality. Riluzole and edaravone are the only approved medications currently being used for amyotrophic lateral sclerosis in clinical settings. However, they can lead to serious complications, such as injuries to the liver and kidney. To date, there is no effective treatment for amyotrophic lateral sclerosis. In this regard, investigations concerning the employment of exosomes, mesenchymal stem cells, and neurotrophic factors to ameliorate amyotrophic lateral sclerosis are attracting considerable attention in the scientific community. Herein, we systematically analyze the relationship relevant to autologous mesenchymal stem cell derived-exosomes, neurotrophic factors and amyotrophic lateral sclerosis. Mesenchymal stem cells modulate immune response, mitigate oxidative stress, promote neuronal regeneration, and differentiate into neuronal and glial cells. Furthermore, exosomes from mesenchymal stem cells exert beneficial effects on their mother cells by preventing abnormal differentiation of mesenchymal stem cells. Similarly, neurotrophic factors regulate inflammatory response, stimulate the neuron repair, and the recovery of neuronal functioning. Therefore, autologous mesenchymal stem cells-derived exosomes combined with neurotrophic factors could potentially be an effective interventional medium for amyotrophic lateral sclerosis.
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Affiliation(s)
- Yingying Ding
- Department of Histology and Embryology, Medical College, Shaoxing University, Zhejiang, China; School of Basic Medical Sciences, Hangzhou Normal University, Zhejiang, China
| | - Benson O A Botchway
- Institute of Neuroscience, Zhejiang University School of Medicine, Hangzhou, China
| | - Yong Zhang
- Department of Histology and Embryology, Medical College, Shaoxing University, Zhejiang, China
| | - Tian Jin
- Department of Histology and Embryology, Medical College, Shaoxing University, Zhejiang, China
| | - Xuehong Liu
- Department of Histology and Embryology, Medical College, Shaoxing University, Zhejiang, China.
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Pastor AM, Blumer R, de la Cruz RR. Extraocular Motoneurons and Neurotrophism. ADVANCES IN NEUROBIOLOGY 2022; 28:281-319. [PMID: 36066830 DOI: 10.1007/978-3-031-07167-6_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Extraocular motoneurons are located in three brainstem nuclei: the abducens, trochlear and oculomotor. They control all types of eye movements by innervating three pairs of agonistic/antagonistic extraocular muscles. They exhibit a tonic-phasic discharge pattern, demonstrating sensitivity to eye position and sensitivity to eye velocity. According to their innervation pattern, extraocular muscle fibers can be classified as singly innervated muscle fiber (SIF), or the peculiar multiply innervated muscle fiber (MIF). SIF motoneurons show anatomical and physiological differences with MIF motoneurons. The latter are smaller and display lower eye position and velocity sensitivities as compared with SIF motoneurons.
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Affiliation(s)
- Angel M Pastor
- Departamento de Fisiología, Universidad de Sevilla, Seville, Spain.
| | - Roland Blumer
- Center of Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
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Hoh JFY. Myosin heavy chains in extraocular muscle fibres: Distribution, regulation and function. Acta Physiol (Oxf) 2021; 231:e13535. [PMID: 32640094 DOI: 10.1111/apha.13535] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 07/02/2020] [Indexed: 12/13/2022]
Abstract
This review examines kinetic properties and distribution of the 11 isoforms of myosin heavy chain (MyHC) expressed in extraocular muscle (EOM) fibre types and the regulation and function of these MyHCs. Although recruitment and discharge characteristics of ocular motoneurons during fixation and eye movements are well documented, work directly linking these properties with motor unit contractile speed and MyHC composition is lacking. Recruitment of motor units according to Henneman's size principle has some support in EOMs but needs consolidation. Both neurogenic and myogenic mechanisms regulate MyHC expression as in other muscle allotypes. Developmentally, multiply-innervated (MIFs) and singly-innervated fibres (SIFs) are derived presumably from distinct myoblast lineages, ending up expressing MyHCs in the slow and fast ends of the kinetic spectrum respectively. They modulate the synaptic inputs of their motoneurons through different retrogradely transported neurotrophins, thereby specifying their tonic and phasic impulse patterns. Immunohistochemical analyses of EOMs regenerating in situ and in limb muscle beds suggest that the very impulse patterns driving various ocular movements equip effectors with appropriate MyHC compositions and speeds to accomplish their tasks. These experiments also suggest that satellite cells of SIFs and MIFs are distinct lineages expressing different MyHCs during regeneration. MyHC compositions and functional characteristics of orbital fibres show longitudinal variations that facilitate linear ocular rotation during saccades. Palisade endings on global MIFs are postulated to respond to active and passive tensions by triggering axon reflexes that play important roles during fixation, saccades and vergence. How EOMs implement Listings law during ocular rotation is discussed.
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Affiliation(s)
- Joseph F. Y. Hoh
- Discipline of Physiology and the Bosch Institute School of Medical Sciences Faculty of Medicine and Health The University of Sydney Sydney NSW Australia
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Neuroprotective Effect of Vascular Endothelial Growth Factor on Motoneurons of the Oculomotor System. Int J Mol Sci 2021; 22:ijms22020814. [PMID: 33467517 PMCID: PMC7830098 DOI: 10.3390/ijms22020814] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/11/2021] [Accepted: 01/13/2021] [Indexed: 01/04/2023] Open
Abstract
Vascular endothelial growth factor (VEGF) was initially characterized as a potent angiogenic factor based on its activity on the vascular system. However, it is now well established that VEGF also plays a crucial role as a neuroprotective factor in the nervous system. A deficit of VEGF has been related to motoneuronal degeneration, such as that occurring in amyotrophic lateral sclerosis (ALS). Strikingly, motoneurons of the oculomotor system show lesser vulnerability to neurodegeneration in ALS compared to other motoneurons. These motoneurons presented higher amounts of VEGF and its receptor Flk-1 than other brainstem pools. That higher VEGF level could be due to an enhanced retrograde input from their target muscles, but it can also be produced by the motoneurons themselves and act in an autocrine way. By contrast, VEGF’s paracrine supply from the vicinity cells, such as glial cells, seems to represent a minor source of VEGF for brainstem motoneurons. In addition, ocular motoneurons experiment an increase in VEGF and Flk-1 level in response to axotomy, not observed in facial or hypoglossal motoneurons. Therefore, in this review, we summarize the differences in VEGF availability that could contribute to the higher resistance of extraocular motoneurons to injury and neurodegenerative diseases.
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Falgairolle M, O'Donovan MJ. Motoneuronal Spinal Circuits in Degenerative Motoneuron Disease. Front Mol Neurosci 2020; 13:74. [PMID: 32523513 PMCID: PMC7261878 DOI: 10.3389/fnmol.2020.00074] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 04/15/2020] [Indexed: 12/22/2022] Open
Abstract
The most evident phenotype of degenerative motoneuron disease is the loss of motor function which accompanies motoneuron death. In both amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA), it is now clear that dysfunction is not restricted to motoneurons but is manifest in the spinal circuits in which motoneurons are embedded. As mounting evidence shows that motoneurons possess more elaborate and extensive connections within the spinal cord than previously realized, it is necessary to consider the role of this circuitry and its dysfunction in the disease process. In this review article, we ask if the selective vulnerability of the different motoneuron types and the relative disease resistance of distinct motoneuron groups can be understood in terms of their intraspinal connections.
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Affiliation(s)
- Mélanie Falgairolle
- Section on Developmental Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
| | - Michael J O'Donovan
- Section on Developmental Neurobiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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Hernández RG, Djebari S, Vélez-Ortiz JM, de la Cruz RR, Pastor AM, Benítez-Temiño B. Short-term plasticity after partial deafferentation in the oculomotor system. Brain Struct Funct 2019; 224:2717-2731. [PMID: 31375981 DOI: 10.1007/s00429-019-01929-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 07/26/2019] [Indexed: 10/26/2022]
Abstract
Medial rectus motoneurons are innervated by two main pontine inputs. The specific function of each of these two inputs remains to be fully understood. Indeed, selective partial deafferentation of medial rectus motoneurons, performed by the lesion of either the vestibular or the abducens input, initially induces similar changes in motoneuronal discharge. However, at longer time periods, the responses to both lesions are dissimilar. Alterations on eye movements and motoneuronal discharge induced by vestibular input transection recover completely 2 months post-lesion, whereas changes induced by abducens internuclear lesion are more drastic and permanent. Functional recovery could be due to some kind of plastic process, such as reactive synaptogenesis, developed by the remaining intact input, which would occupy the vacant synaptic spaces left after lesion. Herein, by means of confocal microscopy, immunocytochemistry and retrograde labeling, we attempt to elucidate the possible plastic processes that take place after partial deafferentation of medial rectus motoneuron. 48 h post-injury, both vestibular and abducens internuclear lesions produced a reduced synaptic coverage on these motoneurons. However, 96 h after vestibular lesion, there was a partial recovery in the number of synaptic contacts. This suggests that there was reactive synaptogenesis. This recovery was preceded by an increase in somatic neurotrophin content, suggesting a role of these molecules in presynaptic axonal sprouting. The rise in synaptic coverage might be due to terminal sprouting performed by the remaining main input, i.e., abducens internuclear neurons. The present results may improve the understanding of this apparently redundant input system.
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Affiliation(s)
- Rosendo G Hernández
- Departamento de Fisiología, Universidad de Sevilla, Avda. Reina Mercedes, 6, 41012, Seville, Spain
| | - Souhail Djebari
- Departamento de Fisiología, Universidad de Sevilla, Avda. Reina Mercedes, 6, 41012, Seville, Spain
| | - José Miguel Vélez-Ortiz
- Departamento de Fisiología, Universidad de Sevilla, Avda. Reina Mercedes, 6, 41012, Seville, Spain
| | - Rosa R de la Cruz
- Departamento de Fisiología, Universidad de Sevilla, Avda. Reina Mercedes, 6, 41012, Seville, Spain
| | - Angel M Pastor
- Departamento de Fisiología, Universidad de Sevilla, Avda. Reina Mercedes, 6, 41012, Seville, Spain.
| | - Beatriz Benítez-Temiño
- Departamento de Fisiología, Universidad de Sevilla, Avda. Reina Mercedes, 6, 41012, Seville, Spain
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Chen H, Amazit L, Lombès M, Le Menuet D. Crosstalk Between Glucocorticoid Receptor and Early-growth Response Protein 1 Accounts for Repression of Brain-derived Neurotrophic Factor Transcript 4 Expression. Neuroscience 2018; 399:12-27. [PMID: 30578973 DOI: 10.1016/j.neuroscience.2018.12.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 12/31/2022]
Abstract
The brain-derived neurotrophic factor (BDNF) is a key player in brain functions such as synaptic plasticity, stress, and behavior. Its gene structure in rodents contains 8 untranslated exons (I to VIII) whose expression is finely regulated and which spliced onto a common and unique translated exon IX. Altered Bdnf expression is associated with many pathologies such as depression, Alzheimer's disease and addiction. Through binding to glucocorticoid receptor (GR), glucocorticoids play a pivotal role for stress responses, mood and neuronal plasticity. We recently showed in neuronal primary culture and in the immortalized neuronal-like BZ cells that GR repressed Bdnf expression, notably the bdnf exon IV containing mRNA isoform (Bdnf4) via GR binding to a short 275-bp sequence of Bdnf promoter. Herein, we demonstrate by transient transfection experiments and mutagenesis in BZ cells that GR interacts with an early growth response protein 1 (EGR1) response element (EGR-RE) located in the transcription start site of Bdnf exon IV promoter. Using Chromatin Immunoprecipitation, we find that both GR and EGR1 bind to this promoter sequence in a glucocorticoid-dependent manner and demonstrate by co-immunoprecipitation that GR and EGR1 are interacting physically. Interestingly, EGR1 has been widely characterized as a regulator of brain plasticity. In conclusion, we deciphered a mechanism by which GR downregulates Bdnf expression, identifying a novel functional crosstalk between glucocorticoid pathways, immediate early growth response proteins and Bdnf. As all these factors are well-recognized germane for brain pathophysiology, these findings may have significant implications in neurosciences as well as in therapeutics.
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Affiliation(s)
- Hui Chen
- Inserm 1185, Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, France
| | - Larbi Amazit
- UMS-32, Institut Biomédical de Bicêtre, Le Kremlin-Bicêtre, France
| | - Marc Lombès
- Inserm 1185, Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, France; Assistance Publique-Hôpitaux de Paris, Hôpital de Bicêtre, Service d'Endocrinologie et des Maladies de la Reproduction, Le Kremlin Bicêtre F-94275, France
| | - Damien Le Menuet
- Inserm 1185, Fac Med Paris Sud, Université Paris-Saclay, Le Kremlin-Bicêtre, France.
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Fleuriet J, McLoon LK. Visualizing Neuronal Adaptation Over Time After Treatment of Strabismus. Invest Ophthalmol Vis Sci 2018; 59:5022-5024. [PMID: 30326069 PMCID: PMC6188464 DOI: 10.1167/iovs.18-25651] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Jérome Fleuriet
- Washington National Primate Research Center, University of Washington, Seattle, Washington, United States
- Department of Ophthalmology, University of Washington, Seattle, Washington, United States
| | - Linda K. McLoon
- Department of Ophthalmology and Visual Neurosciences, Minneapolis, Minnesota, United States;
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, Minnesota, United States
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