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Takatoh J, Prevosto V, Thompson PM, Lu J, Chung L, Harrahill A, Li S, Zhao S, He Z, Golomb D, Kleinfeld D, Wang F. The whisking oscillator circuit. Nature 2022; 609:560-568. [PMID: 36045290 PMCID: PMC10038238 DOI: 10.1038/s41586-022-05144-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 07/25/2022] [Indexed: 11/09/2022]
Abstract
Central oscillators are primordial neural circuits that generate and control rhythmic movements1,2. Mechanistic understanding of these circuits requires genetic identification of the oscillator neurons and their synaptic connections to enable targeted electrophysiological recording and causal manipulation during behaviours. However, such targeting remains a challenge with mammalian systems. Here we delimit the oscillator circuit that drives rhythmic whisking-a motor action that is central to foraging and active sensing in rodents3,4. We found that the whisking oscillator consists of parvalbumin-expressing inhibitory neurons located in the vibrissa intermediate reticular nucleus (vIRtPV) in the brainstem. vIRtPV neurons receive descending excitatory inputs and form recurrent inhibitory connections among themselves. Silencing vIRtPV neurons eliminated rhythmic whisking and resulted in sustained vibrissae protraction. In vivo recording of opto-tagged vIRtPV neurons in awake mice showed that these cells spike tonically when animals are at rest, and transition to rhythmic bursting at the onset of whisking, suggesting that rhythm generation is probably the result of network dynamics, as opposed to intrinsic cellular properties. Notably, ablating inhibitory synaptic inputs to vIRtPV neurons quenched their rhythmic bursting, impaired the tonic-to-bursting transition and abolished regular whisking. Thus, the whisking oscillator is an all-inhibitory network and recurrent synaptic inhibition has a key role in its rhythmogenesis.
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Affiliation(s)
- Jun Takatoh
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Neurobiology, Duke University, Durham, NC, USA.
| | - Vincent Prevosto
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Neurobiology, Duke University, Durham, NC, USA
| | - P M Thompson
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Jinghao Lu
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Neurobiology, Duke University, Durham, NC, USA
| | - Leeyup Chung
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
- Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - Andrew Harrahill
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Shun Li
- Department of Neurobiology, Duke University, Durham, NC, USA
| | - Shengli Zhao
- Department of Neurobiology, Duke University, Durham, NC, USA
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA
- Department of Neurology, Harvard Medical School, Boston, MA, USA
- Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| | - David Golomb
- Department of Physiology and Cell Biology, Ben Gurion University, Be'er Sheva, Israel
- Department of Physics, Ben Gurion University, Be'er Sheva, Israel
- Zlotowski Center for Neuroscience, Ben Gurion University, Be'er Sheva, Israel
| | - David Kleinfeld
- Department of Physics, University of California at San Diego, La Jolla, CA, USA
- Department of Neurobiology, University of California at San Diego, La Jolla, CA, USA
| | - Fan Wang
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Neurobiology, Duke University, Durham, NC, USA.
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2
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Abstract
During early development, the hindbrain is sub-divided into rhombomeres that underlie the organisation of neurons and adjacent craniofacial tissues. A gene regulatory network of signals and transcription factors establish and pattern segments with a distinct anteroposterior identity. Initially, the borders of segmental gene expression are imprecise, but then become sharply defined, and specialised boundary cells form. In this Review, we summarise key aspects of the conserved regulatory cascade that underlies the formation of hindbrain segments. We describe how the pattern is sharpened and stabilised through the dynamic regulation of cell identity, acting in parallel with cell segregation. Finally, we discuss evidence that boundary cells have roles in local patterning, and act as a site of neurogenesis within the hindbrain.
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Affiliation(s)
- Robb Krumlauf
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA.,Dept of Anatomy and Cell Biology, Kansas University Medical School, Kansas City, KS 66160, USA
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3
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Li S, Wang F. Vertebrate Evolution Conserves Hindbrain Circuits despite Diverse Feeding and Breathing Modes. eNeuro 2021; 8:ENEURO.0435-20.2021. [PMID: 33707205 PMCID: PMC8174041 DOI: 10.1523/eneuro.0435-20.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 01/08/2021] [Accepted: 01/12/2021] [Indexed: 12/21/2022] Open
Abstract
Feeding and breathing are two functions vital to the survival of all vertebrate species. Throughout the evolution, vertebrates living in different environments have evolved drastically different modes of feeding and breathing through using diversified orofacial and pharyngeal (oropharyngeal) muscles. The oropharyngeal structures are controlled by hindbrain neural circuits. The developing hindbrain shares strikingly conserved organizations and gene expression patterns across vertebrates, thus begs the question of how a highly conserved hindbrain generates circuits subserving diverse feeding/breathing patterns. In this review, we summarize major modes of feeding and breathing and principles underlying their coordination in many vertebrate species. We provide a hypothesis for the existence of a common hindbrain circuit at the phylotypic embryonic stage controlling oropharyngeal movements that is shared across vertebrate species; and reconfiguration and repurposing of this conserved circuit give rise to more complex behaviors in adult higher vertebrates.
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Affiliation(s)
- Shun Li
- Department of Neurobiology, Duke University, Durham, NC 27710
| | - Fan Wang
- Department of Neurobiology, Duke University, Durham, NC 27710
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4
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Whitaker-Fornek JR, Nelson JK, Lybbert CW, Pilarski JQ. Development and regulation of breathing rhythms in embryonic and hatchling birds. Respir Physiol Neurobiol 2019; 269:103246. [DOI: 10.1016/j.resp.2019.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 05/19/2019] [Accepted: 06/23/2019] [Indexed: 11/28/2022]
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5
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Pickett KL, Stein PS, Vincen-Brown MA, Pilarski JQ. Maturation of Breathing-Related Inhibitory Neurotransmission in the Medulla Oblongata of the Embryonic and Perinatal Zebra Finch (Taeniopygia guttata). Dev Neurobiol 2018; 78:1081-1096. [PMID: 30160056 DOI: 10.1002/dneu.22632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 07/07/2018] [Accepted: 07/08/2018] [Indexed: 11/05/2022]
Abstract
The medullary portion of the embryonic zebra finch hindbrain was isolated and superfused with physiologically relevant artificial cerebral spinal fluid. This in vitro preparation produced uninterrupted rhythmic episodes of neural activity via cranial nerve IX (glossopharyngeal) from embryonic day 4 (E4) through hatching on E14. Cranial nerve IX carries motor activity to the glottis during the inspiratory phase of breathing, and we focused on the role of synaptic inhibition during the embryonic and perinatal maturation of this branchiomotor outflow. We show that spontaneous neural activity (SNA) is first observed on E4 and temporally transforms as the embryo ages. To start, SNA is dependent on the excitatory actions of GABAA and glycine. As the embryo continues to develop, GABAergic and glycinergic neurotransmission take on a modulatory role, albeit an excitatory one, through E10. After that, data show that GABAergic and glycinergic neurotransmission switches to a phenotype consistent with inhibition, coincident with the onset of functional breathing. We also report that the inhibitory action of GABAergic and glycinergic receptor gating is not necessary for the spontaneous generation of branchiomotor motor rhythms in these birds near hatching. This is the first report focusing on the development of central breathing-related inhibitory neurotransmission in birds during the entire period of embryogenesis.
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Affiliation(s)
- Kaci L Pickett
- Department of Biological Sciences, Idaho State University, Pocatello, Idaho, 83209-8007
| | - Paxton S Stein
- Department of Biological Sciences, Idaho State University, Pocatello, Idaho, 83209-8007
| | | | - Jason Q Pilarski
- Department of Biological Sciences, Idaho State University, Pocatello, Idaho, 83209-8007.,Dental Sciences, Idaho State University, Pocatello, Idaho, 83209-8007
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6
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Momose-Sato Y, Sato K. Development of Spontaneous Activity in the Avian Hindbrain. Front Neural Circuits 2016; 10:63. [PMID: 27570506 PMCID: PMC4981603 DOI: 10.3389/fncir.2016.00063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 07/29/2016] [Indexed: 11/13/2022] Open
Abstract
Spontaneous activity in the developing central nervous system occurs before the brain responds to external sensory inputs, and appears in the hindbrain and spinal cord as rhythmic electrical discharges of cranial and spinal nerves. This spontaneous activity recruits a large population of neurons and propagates like a wave over a wide region of the central nervous system. Here, we review spontaneous activity in the chick hindbrain by focusing on this large-scale synchronized activity. Asynchronous activity that is expressed earlier than the above mentioned synchronized activity and activity originating in midline serotonergic neurons are also briefly mentioned.
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Affiliation(s)
- Yoko Momose-Sato
- Department of Nutrition and Dietetics, College of Nutrition, Kanto Gakuin University Yokohama, Japan
| | - Katsushige Sato
- Department of Health and Nutrition Sciences, Faculty of Human Health, Komazawa Women's University Tokyo, Japan
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7
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Vincen-Brown MA, Revill AL, Pilarski JQ. Activity-dependent plasticity in the isolated embryonic avian brainstem following manipulations of rhythmic spontaneous neural activity. Respir Physiol Neurobiol 2016; 229:24-33. [PMID: 27025229 DOI: 10.1016/j.resp.2016.03.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Revised: 02/20/2016] [Accepted: 03/22/2016] [Indexed: 02/06/2023]
Abstract
When rhythmic spontaneous neural activity (rSNA) first appears in the embryonic chick brainstem and cranial nerve motor axons it is principally driven by nicotinic neurotransmission (NT). At this early age, the nicotinic acetylcholine receptor (nAChR) agonist nicotine is known to critically disrupt rSNA at low concentrations (0.1-0.5μM), which are levels that mimic the blood plasma levels of a fetus following maternal cigarette smoking. Thus, we quantified the effect of persistent exposure to exogenous nicotine on rSNA using an in vitro developmental model. We found that rSNA was eliminated by continuous bath application of exogenous nicotine, but rSNA recovered activity within 6-12h despite the persistent activation and desensitization of nAChRs. During the recovery period rSNA was critically driven by chloride-mediated membrane depolarization instead of nicotinic NT. To test whether this observed compensation was unique to the antagonism of nicotinic NT or whether the loss of spiking behavior also played a role, we eliminated rSNA by lowering overall excitatory drive with a low [K(+)]o superfusate. In this context, rSNA again recovered, although the recovery time was much quicker, and exhibited a lower frequency, higher duration, and an increase in the number of bursts per episode when compared to control embryos. Importantly, we show that the main compensatory response to lower overall excitatory drive, similar to nicotinergic block, is a result of potentiated chloride mediated membrane depolarization. These results support increasing evidence that early neural circuits sense spiking behavior to maintain primordial bioelectric rhythms. Understanding the nature of developmental plasticity in the nervous system, especially versions that preserve rhythmic behaviors following clinically meaningful environmental stimuli, both normal and pathological, will require similar studies to determine the consequences of feedback compensation at more mature chronological ages.
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Affiliation(s)
| | - Ann L Revill
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
| | - Jason Q Pilarski
- Department of Biological Sciences, Idaho State University, Pocatello, ID, United states; Department of Dental Sciences, Idaho State University, Pocatello, ID, United states.
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8
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Corner MA, Schenck CH. Perchance to dream? Primordial motor activity patterns in vertebrates from fish to mammals: their prenatal origin, postnatal persistence during sleep, and pathological reemergence during REM sleep behavior disorder. Neurosci Bull 2015; 31:649-62. [PMID: 26319263 PMCID: PMC5563724 DOI: 10.1007/s12264-015-1557-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Accepted: 06/25/2015] [Indexed: 12/14/2022] Open
Abstract
An overview is presented of the literature dealing with sleep-like motility and concomitant neuronal activity patterns throughout the life cycle in vertebrates, ectothermic as well as endothermic. Spontaneous, periodically modulated, neurogenic bursts of non-purposive movements are a universal feature of larval and prenatal behavior, which in endothermic animals (i.e. birds and mammals) continue to occur periodically throughout life. Since the entire body musculature is involved in ever-shifting combinations, it is proposed that these spontaneously active periods be designated as 'rapid-BODY-movement' (RBM) sleep. The term 'rapid-EYE-movement (REM) sleep', characterized by attenuated muscle contractions and reduced tonus, can then be reserved for sleep at later stages of development. Mature stages of development in which sustained muscle atonia is combined with 'paradoxical arousal' of cortical neuronal firing patterns indisputably represent the evolutionarily most recent aspect of REM sleep, but more research with ectothermic vertebrates, such as fish, amphibians and reptiles, is needed before it can be concluded (as many prematurely have) that RBM is absent in these species. Evidence suggests a link between RBM sleep in early development and the clinical condition known as 'REM sleep behavior disorder (RBD)', which is characterized by the resurgence of periodic bouts of quasi-fetal motility that closely resemble RBM sleep. Early developmental neuromotor risk factors for RBD in humans also point to a relationship between RBM sleep and RBD.
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Affiliation(s)
- Michael A Corner
- Netherlands Institute for Brain Research, Amsterdam, The Netherlands
| | - Carlos H Schenck
- Minnesota Regional Sleep Disorders Center, Hennepin County Medical Center and University of Minnesota, Minneapolis, Minnesota, 55415, USA.
- Departments of Psychiatry, Hennepin County Medical Center and University of Minnesota, Minneapolis, Minnesota, 55415, USA.
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9
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Vincen-Brown MA, Whitesitt KC, Quick FG, Pilarski JQ. Studying respiratory rhythm generation in a developing bird: Hatching a new experimental model using the classic in vitro brainstem-spinal cord preparation. Respir Physiol Neurobiol 2015; 224:62-70. [PMID: 26310580 DOI: 10.1016/j.resp.2015.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Revised: 08/18/2015] [Accepted: 08/19/2015] [Indexed: 01/17/2023]
Abstract
It has been more than thirty years since the in vitro brainstem-spinal cord preparation was first presented as a method to study automatic breathing behaviors in the neonatal rat. This straightforward preparation has led to an incredible burst of information about the location and coordination of several spontaneously active microcircuits that form the ventrolateral respiratory network of the brainstem. Despite these advances, our knowledge of the mechanisms that regulate central breathing behaviors is still incomplete. Investigations into the nature of spontaneous breathing rhythmicity have almost exclusively focused on mammals, and there is a need for comparative experimental models to evaluate several unresolved issues from a different perspective. With this in mind, we sought to develop a new avian in vitro model with the long term goal to better understand questions associated with the ontogeny of respiratory rhythm generation, neuroplasticity, and whether multiple, independent oscillators drive the major phases of breathing. The fact that birds develop in ovo provides unparalleled access to central neuronal networks throughout the prenatal period - from embryo to hatchling - that are free from confounding interactions with mother. Previous studies using in vitro avian models have been strictly limited to the early embryonic period. Consequently, the details and even the presence of brainstem derived breathing-related rhythmogenesis in birds have never been described. In the present study, we used the altricial zebra finch (Taeniopygia guttata) and show robust spontaneous motor outflow through cranial motor nerve IX, which is first detectable on embryonic day four and continues through prenatal and early postnatal development without interruption. We also show that brainstem oscillations change dramatically over the course of prenatal development, sometimes within hours, which suggests rapid maturational modifications in growth and connectivity. We propose that this experimental preparation will be useful for a variety of studies aimed at testing the biophysical and synaptic properties of neurons that participate in the unique spatiotemporal patterns of avian breathing behaviors, especially in the context of early development.
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Affiliation(s)
| | - Kaitlyn C Whitesitt
- Department of Biological Sciences, Idaho State University, Pocatello, ID, 83 209, USA
| | - Forrest G Quick
- Department of Biological Sciences, Idaho State University, Pocatello, ID, 83 209, USA
| | - Jason Q Pilarski
- Department of Biological Sciences, Idaho State University, Pocatello, ID, 83 209, USA; Department of Dental Sciences, Idaho State University, Pocatello, ID, 83 209 USA.
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10
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Momose-Sato Y, Sato K. Maintenance of the large-scale depolarization wave in the embryonic chick brain against deprivation of the rhythm generator. Neuroscience 2014; 266:186-96. [PMID: 24568731 DOI: 10.1016/j.neuroscience.2014.02.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 02/11/2014] [Accepted: 02/12/2014] [Indexed: 11/24/2022]
Abstract
Widely correlated spontaneous activity in the developing nervous system is transiently expressed and is considered to play a fundamental role in neural circuit formation. The depolarization wave, which spreads over a long distance along the neuraxis, maximally extending to the lumbosacral cord and forebrain, is an example of this spontaneous activity. Although the depolarization wave is typically initiated in the spinal cord in intact preparations, spontaneous discharges have also been detected in the isolated brainstem. Although this suggests that the brainstem has the ability to generate spontaneous activity, but is paced by a caudal rhythm generator of higher excitability, a number of questions remains. Does brainstem activity simply appear as a passive consequence, or does any active change occur in the brainstem network to compensate for this activity? If the latter is the case, does this compensation occur equally at different developmental stages? Where is the new rhythm generator in the isolated brainstem? To answer these questions, we optically analyzed spatio-temporal patterns of activity detected from the chick brainstem before and after transection at the obex. The results revealed that the depolarization wave was homeostatically maintained, which was characterized by an increase in excitability and/or the number of neurons recruited to the wave. The wave was more easily maintained in younger embryos. Furthermore, we demonstrated that the ability of brainstem neurons to perform such an active compensation was not lost even at the stage when the depolarization wave was no longer observed in the intact brainstem.
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Affiliation(s)
- Y Momose-Sato
- Department of Health and Nutrition, College of Human Environmental Studies, Kanto Gakuin University, Kanazawa-ku, Yokohama 236-8503, Japan.
| | - K Sato
- Department of Health and Nutrition Sciences, Faculty of Human Health, Komazawa Women's University, Inagi-shi, Tokyo 206-8511, Japan.
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11
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Tyrosine phosphorylation of GABAA receptor γ2-subunit regulates tonic and phasic inhibition in the thalamus. J Neurosci 2013; 33:12718-27. [PMID: 23904608 PMCID: PMC4400286 DOI: 10.1523/jneurosci.0388-13.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
GABA-mediated tonic and phasic inhibition of thalamic relay neurons of the dorsal lateral geniculate nucleus (dLGN) was studied after ablating tyrosine (Y) phosphorylation of receptor γ2-subunits. As phosphorylation of γ2 Y365 and Y367 reduces receptor internalization, to understand their importance for inhibition we created a knock-in mouse in which these residues are replaced by phenylalanines. On comparing wild-type (WT) and γ2(Y365/367F)+/- (HT) animals (homozygotes are not viable in utero), the expression levels of GABAA receptor α4-subunits were increased in the thalamus of female, but not male mice. Raised δ-subunit expression levels were also observed in female γ2(Y365/367F) +/- thalamus. Electrophysiological analyses revealed no difference in the level of inhibition in male WT and HT dLGN, while both the spontaneous inhibitory postsynaptic activity and the tonic current were significantly augmented in female HT relay cells. The sensitivity of tonic currents to the δ-subunit superagonist THIP, and the blocker Zn(2+), were higher in female HT relay cells. This is consistent with upregulation of extrasynaptic GABAA receptors containing α4- and δ-subunits to enhance tonic inhibition. In contrast, the sensitivity of GABAA receptors mediating inhibition in the female γ2(Y356/367F) +/- to neurosteroids was markedly reduced compared with WT. We conclude that disrupting tyrosine phosphorylation of the γ2-subunit activates a sex-specific increase in tonic inhibition, and this most likely reflects a genomic-based compensation mechanism for the reduced neurosteroid sensitivity of inhibition measured in female HT relay neurons.
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12
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Momose-Sato Y, Sato K. Large-scale synchronized activity in the embryonic brainstem and spinal cord. Front Cell Neurosci 2013; 7:36. [PMID: 23596392 PMCID: PMC3625830 DOI: 10.3389/fncel.2013.00036] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Accepted: 03/20/2013] [Indexed: 01/09/2023] Open
Abstract
In the developing central nervous system, spontaneous activity appears well before the brain responds to external sensory inputs. One of the earliest activities is observed in the hindbrain and spinal cord, which is detected as rhythmic electrical discharges of cranial and spinal motoneurons or oscillations of Ca(2+)- and voltage-related optical signals. Shortly after the initial expression, the spontaneous activity appearing in the hindbrain and spinal cord exhibits a large-scale correlated wave that propagates over a wide region of the central nervous system, maximally extending to the lumbosacral cord and to the forebrain. In this review, we describe several aspects of this synchronized activity by focusing on the basic properties, development, origin, propagation pattern, pharmacological characteristics, and possible mechanisms underlying the generation of the activity. These profiles differ from those of the respiratory and locomotion pattern generators observed in the mature brainstem and spinal cord, suggesting that the wave is primordial activity that appears during a specific period of embryonic development and plays some important roles in the development of the central nervous system.
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Affiliation(s)
- Yoko Momose-Sato
- Department of Health and Nutrition, College of Human Environmental Studies, Kanto Gakuin UniversityYokohama, Japan
| | - Katsushige Sato
- Department of Health and Nutrition Sciences, Faculty of Human Health, Komazawa Women's UniversityTokyo, Japan
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13
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Fogarty MJ, Smallcombe KL, Yanagawa Y, Obata K, Bellingham MC, Noakes PG. Genetic deficiency of GABA differentially regulates respiratory and non-respiratory motor neuron development. PLoS One 2013; 8:e56257. [PMID: 23457538 PMCID: PMC3574162 DOI: 10.1371/journal.pone.0056257] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 01/07/2013] [Indexed: 11/25/2022] Open
Abstract
Central nervous system GABAergic and glycinergic synaptic activity switches from postsynaptic excitation to inhibition during the stage when motor neuron numbers are being reduced, and when synaptic connections are being established onto and by motor neurons. In mice this occurs between embryonic (E) day 13 and birth (postnatal day 0). Our previous work on mice lacking glycinergic transmission suggested that altered motor neuron activity levels correspondingly regulated motor neuron survival and muscle innervation for all respiratory and non respiratory motor neuron pools, during this period of development [1]. To determine if GABAergic transmission plays a similar role, we quantified motor neuron number and the extent of muscle innervation in four distinct regions of the brain stem and spinal cord; hypoglossal, phrenic, brachial and lumbar motor pools, in mice lacking the enzyme GAD67. These mice display a 90% drop in CNS GABA levels ( [2]; this study). For respiratory-based motor neurons (hypoglossal and phrenic motor pools), we have observed significant drops in motor neuron number (17% decline for hypoglossal and 23% decline for phrenic) and muscle innervations (55% decrease). By contrast for non-respiratory motor neurons of the brachial lateral motor column, we have observed an increase in motor neuron number (43% increase) and muscle innervations (99% increase); however for more caudally located motor neurons within the lumbar lateral motor column, we observed no change in either neuron number or muscle innervation. These results show in mice lacking physiological levels of GABA, there are distinct regional changes in motor neuron number and muscle innervation, which appear to be linked to their physiological function and to their rostral-caudal position within the developing spinal cord. Our results also suggest that for more caudal (lumbar) regions of the spinal cord, the effect of GABA is less influential on motor neuron development compared to that of glycine.
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Affiliation(s)
- Matthew J Fogarty
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
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Champagnat J, Morin-Surun MP, Bouvier J, Thoby-Brisson M, Fortin G. Prenatal development of central rhythm generation. Respir Physiol Neurobiol 2011; 178:146-55. [PMID: 21527363 DOI: 10.1016/j.resp.2011.04.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Revised: 04/08/2011] [Accepted: 04/12/2011] [Indexed: 12/01/2022]
Abstract
Foetal breathing in mice results from prenatal activity of the two coupled hindbrain oscillators considered to be responsible for respiratory rhythm generation after birth: the pre-Bötzinger complex (preBötC) is active shortly before the onset of foetal breathing; the parafacial respiratory group (e-pF in embryo) starts activity one day earlier. Transcription factors have been identified that are essential to specify neural progenitors and lineages forming each of these oscillators during early development of the neural tube: Hoxa1, Egr2 (Krox20), Phox2b, Lbx1 and Atoh1 for the e-pF; Dbx1 and Evx1 for the preBötC which eventually grow contralateral axons requiring expression of Robo3. Inactivation of the genes encoding these factors leads to mis-specification of these neurons and distinct breathing abnormalities: apneic patterns and loss of central chemosensitivity for the e-pF (central congenital hypoventilation syndrome, CCHS, in humans), complete loss of breathing for the preBötC, right-left desynchronized breathing in Robo3 mutants. Mutations affecting development in more rostral (pontine) respiratory territories change the shape of the inspiratory drive without affecting the rhythm. Other (primordial) embryonic oscillators start in the mouse three days before the e-pF, to generate low frequency (LF) rhythms that are probably required for activity-dependent development of neurones at embryonic stages; in the foetus, however, they are actively silenced to avoid detrimental interaction with the on-going respiratory rhythm. Altogether, these observations provide a strong support to the previously proposed hypothesis that the functional organization of the respiratory generator is specified at early stages of development and is dual in nature, comprising two serially non-homologous oscillators.
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Affiliation(s)
- Jean Champagnat
- Neurobiologie et Développement (UPR 3294, CNRS), Neuro-Sud Paris (IFR 144), Centre de Recherche de Gif-sur Yvette (CNRS, FRC 3115), Gif-sur-Yvette, France.
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Genetic factors determining the functional organization of neural circuits controlling rhythmic movements the murine embryonic parafacial rhythm generator. PROGRESS IN BRAIN RESEARCH 2011. [PMID: 21111199 DOI: 10.1016/b978-0-444-53613-6.00003-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
In mammals, fetal movements governed by central pattern generators are essential for the development of adaptive behaviors such as breathing, walking, and chewing, which are vital after birth. Combining targeted mutations and genetic fate mapping can help to define the molecular determinants that control the development of these central pattern generators. In this chapter, recent results are presented on the embryonic parafacial (e-pF) rhythm generator, one of the two oscillators involved in controlling the breathing behavior and chemosensitive responsiveness.
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Meillerais A, Champagnat J, Morin-Surun M. Extracellular calcium induces quiescence of the low-frequency embryonic motor rhythm in the mouse isolated brainstem. J Neurosci Res 2010; 88:3555-65. [DOI: 10.1002/jnr.22518] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Revised: 08/16/2010] [Accepted: 08/20/2010] [Indexed: 11/11/2022]
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17
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Deficits in spatial memory correlate with modified {gamma}-aminobutyric acid type A receptor tyrosine phosphorylation in the hippocampus. Proc Natl Acad Sci U S A 2009; 106:20039-44. [PMID: 19903874 DOI: 10.1073/pnas.0908840106] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fast synaptic inhibition in the brain is largely mediated by gamma-aminobutyric acid receptors (GABA(A)R). While the pharmacological manipulation of GABA(A)R function by therapeutic agents, such as benzodiazepines can have profound effects on neuronal excitation and behavior, the endogenous mechanisms neurons use to regulate the efficacy of synaptic inhibition and their impact on behavior remains poorly understood. To address this issue, we created a knock-in mouse in which tyrosine phosphorylation of the GABA(A)Rs gamma2 subunit, a posttranslational modification that is critical for their functional modulation, has been ablated. These animals exhibited enhanced GABA(A)R accumulation at postsynaptic inhibitory synaptic specializations on pyramidal neurons within the CA3 subdomain of the hippocampus, primarily due to aberrant trafficking within the endocytic pathway. This enhanced inhibition correlated with a specific deficit in spatial object recognition, a behavioral paradigm dependent upon CA3. Thus, phospho-dependent regulation of GABA(A)R function involving just two tyrosine residues in the gamma2 subunit provides an input-specific mechanism that not only regulates the efficacy of synaptic inhibition, but has behavioral consequences.
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18
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Fong AY, Zimmer MB, Milsom WK. The conditional nature of the “Central Rhythm Generator” and the production of episodic breathing. Respir Physiol Neurobiol 2009; 168:179-87. [DOI: 10.1016/j.resp.2009.05.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 05/20/2009] [Accepted: 05/28/2009] [Indexed: 12/01/2022]
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19
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Mochida H, Fortin G, Champagnat J, Glover JC. Differential Involvement of Projection Neurons During Emergence of Spontaneous Activity in the Developing Avian Hindbrain. J Neurophysiol 2009; 101:591-602. [DOI: 10.1152/jn.90835.2008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To better characterize the emergence of spontaneous neuronal activity in the developing hindbrain, spontaneous activity was recorded optically from defined projection neuron populations in isolated preparations of the brain stem of the chicken embryo. Ipsilaterally projecting reticulospinal (RS) neurons and several groups of vestibuloocular (VO) neurons were labeled retrogradely with Calcium Green-1 dextran amine and spontaneous calcium transients were recorded using a charge-coupled-device camera mounted on a fluorescence microscope. Simultaneous extracellular recordings were made from one of the trigeminal motor nerves (nV) to register the occurrence of spontaneous synchronous bursts of activity. Two types of spontaneous activity were observed: synchronous events (SEs), which occurred in register with spontaneous bursts in nV once every few minutes and were tetrodotoxin (TTX) dependent, and asynchronous events (AEs), which occurred in the intervals between SEs and were TTX resistant. AEs occurred developmentally before SEs and were in general smaller and more variable in amplitude than SEs. SEs appeared at the same stage as nV bursts early on embryonic day 4, first in RS neurons and then in VO neurons. All RS neurons participated equally in SEs from the outset, whereas different subpopulations of VO neurons participated differentially, both in terms of the proportion of neurons that exhibited SEs, the fidelity with which the SEs in individual neurons followed the nV bursts, and the developmental stage at which SEs appeared and matured. The results show that spontaneous activity is expressed heterogeneously among hindbrain projection neuron populations, suggesting its differential involvement in the formation of different functional neuronal circuits.
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20
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Narita Y, Rijli FM. Hox genes in neural patterning and circuit formation in the mouse hindbrain. Curr Top Dev Biol 2009; 88:139-67. [PMID: 19651304 DOI: 10.1016/s0070-2153(09)88005-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The mammalian hindbrain is the seat of regulation of several vital functions that involve many of the organ systems of the body. Such functions are controlled through the activity of intricate arrays of neuronal circuits and connections. The establishment of ordered patterns of neuronal specification, migration, and axonal topographic connectivity during development is crucial to build such a complex network of circuits and functional connectivity in the mature hindbrain. The early development of the vertebrate hindbrain proceeds according to a fundamental metameric partitioning along the anteroposterior axis into cellular compartments known as rhombomeres. Such an organization has been highly conserved in vertebrate evolution and has a fundamental impact on the hindbrain adult structure, nuclear organization, and connectivity. Here, we review the cellular and molecular mechanisms underlying hindbrain neuronal circuitry in the mouse, with a specific focus on the role of the homeodomain transcription factors of the Hox gene family. The Hox genes are crucial determinants of rhombomere segmental identity and anteroposterior patterning. However, recent findings suggest that, in addition to their well-known roles at early embryonic stages, the Hox genes may play important roles also in later aspect of neuronal circuit development, including stereotypic neuronal migration, axon pathfinding, and topographic mapping of connectivity.
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Affiliation(s)
- Yuichi Narita
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
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21
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Mochida H, Sato K, Momose-Sato Y. Switching of the transmitters that mediate hindbrain correlated activity in the chick embryo. Eur J Neurosci 2008; 29:14-30. [PMID: 19087161 DOI: 10.1111/j.1460-9568.2008.06569.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Widely propagating correlated neuronal activity is a hallmark of the developing nervous system. The activity is usually mediated by multiple transmitters, and the contribution of gap junctions has also been suggested in several systems. In some structures, such as the retina and spinal cord, it has been shown that the dominant transmitter mediating the correlated wave switches from acetylcholine to glutamate during development, although the functional significance of this phenomenon has not been clarified. An important question is whether such a transmitter switch occurs in other systems, especially in the brain. In the present study, we demonstrate that the major transmitter mediating correlated wave activity in the embryonic chick hindbrain changes from acetylcholine/gamma-aminobutyric acid (GABA)/glycine to glutamate/GABA as development proceeds. The results show for the first time that the dominant transmitter switches from acetylcholine to glutamate in a region other than the retina and spinal cord. This finding sheds more light on the role of nicotinic acetylcholine receptors in the generation of correlated wave activity, which is considered to regulate the development of the nervous system.
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Affiliation(s)
- Hiraku Mochida
- Department of Psychiatry, Graduate School and Faculty of Medicine, Kobe University, Kobe, Japan
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22
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Bouvier J, Autran S, Fortin G, Champagnat J, Thoby-Brisson M. Acute role of the brain-derived neurotrophic factor (BDNF) on the respiratory neural network activity in mice in vitro. ACTA ACUST UNITED AC 2007; 100:290-6. [PMID: 17628454 DOI: 10.1016/j.jphysparis.2007.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
In humans, several pathologies are associated with disturbances of the respiratory control, some of them including alteration in the brain-derived neurotrophic factor (BDNF) signalling pathway. BDNF has long been known as a neurotrophic factor involved in survival, differentiation and maintenance of neuronal populations in the peripheral and central nervous system. More recently BDNF has also been discovered to be a potent neuromodulator with acute effects on neuronal excitability and synaptic plasticity. Animals deleted for the gene encoding BDNF exhibit respiratory alteration suggesting an important but yet undefined role of the neurotrophin in respiratory rhythmogenesis either by a trophic and/or an acute action. The possibility that BDNF might exert an acute regulatory role on the rhythmic activity of the respiratory generator of the pre-Bötzinger complex has been recently examined in newborn mice in vitro. Results obtained, reviewed in the present paper, will help getting insights in respiratory rhythm regulatory mechanisms that involve BDNF signalling.
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Affiliation(s)
- Julien Bouvier
- Laboratoire de Neurobiologie Génétique et Intégrative Institut Alfred Fessard, CNRS UPR2216, 1 avenue de la terrasse, 91198 Gif sur Yvette, France
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23
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Borday C, Vias C, Autran S, Thoby-Brisson M, Champagnat J, Fortin G. The pre-Bötzinger oscillator in the mouse embryo. ACTA ACUST UNITED AC 2007; 100:284-9. [PMID: 17628453 DOI: 10.1016/j.jphysparis.2007.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Studies of the sites and mechanisms involved in mammalian respiratory rhythm generation point to two clusters of rhythmic neurons forming a coupled oscillator network within the brainstem. The location of these oscillators, the pre-Bötzinger complex (preBötC) at vagal level, and the para-facial respiratory group at facial level, probably result from regional patterning schemes specifying neural types in the hindbrain during embryogenesis. Here, we report evidence that the preBötC oscillator (i) is first active at embryonic stages, (ii) originates in the post-otic hindbrain neural tube and (iii) requires the glutamate vesicular transporter 2 for rhythm generation.
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Affiliation(s)
- C Borday
- Neurobiologie Génétique et Intégrative, Institut de Neurobiologie Alfred Fessard, CNRS, 1 av. de la terrasse, 91198 Gif sur Yvette, France
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24
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Momose-Sato Y, Sato K, Kinoshita M. Spontaneous depolarization waves of multiple origins in the embryonic rat CNS. Eur J Neurosci 2007; 25:929-44. [PMID: 17331191 DOI: 10.1111/j.1460-9568.2007.05352.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
During development, correlated neuronal activity plays an important role in the establishment of the central nervous system (CNS). We have previously reported that a widely propagating correlated neuronal activity, termed the depolarization wave, is evoked by various sensory inputs. A remarkable feature of the depolarization wave is that it spreads broadly through the brain and spinal cord. In the present study, we examined whether the depolarization wave occurs spontaneously in the embryonic rat CNS and, if so, where it originates. In E15-16 rat embryos, spontaneous optically-revealed signals appeared in association with the rhythmic discharges of cranial motoneurons and propagated widely with similar characteristics to the evoked depolarization wave. At E15, the spontaneous wave mostly originated in the cervical to upper lumbar cords. At E16, the wave was predominantly generated in the lumbosacral cord although a wave associated with the second oscillatory burst was initiated in the rostral cord. At E16, a few waves also originated in the rostral ventrolateral medulla and the dorsomedial pons. When the influence of the caudal cord was removed by transecting the spinal cord, the contribution of the medulla and pons became more significant. These results show that the depolarization wave can be triggered by the spontaneous activity of multiple neuronal populations which are distributed widely from the pons to the lumbosacral cord, although the spinal cord usually plays a predominant role. This network possibly works as a self-distributing system that maintains the incidence and complicated patterns of the correlated activity in the developing CNS.
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Affiliation(s)
- Yoko Momose-Sato
- Department of Physiology, Tokyo Medical and Dental University, Graduate School and Faculty of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
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25
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Borday C, Coutinho A, Germon I, Champagnat J, Fortin G. Pre-/post-otic rhombomeric interactions control the emergence of a fetal-like respiratory rhythm in the mouse embryo. ACTA ACUST UNITED AC 2006; 66:1285-301. [PMID: 16967510 DOI: 10.1002/neu.20271] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
How regional patterning of the neural tube in vertebrate embryos may influence the emergence and the function of neural networks remains elusive. We have begun to address this issue in the embryonic mouse hindbrain by studying rhythmogenic properties of different neural tube segments. We have isolated pre- and post-otic hindbrain segments and spinal segments of the mouse neural tube, when they form at embryonic day (E) 9, and grafted them into the same positions in stage-matched chick hosts. Three days after grafting, in vitro recordings of the activity in the cranial nerves exiting the grafts indicate that a high frequency (HF) rhythm (order: 10 bursts/min) is generated in post-otic segments while more anterior pre-otic and more posterior spinal territories generate a low frequency (LF) rhythm (order: 1 burst/min). Comparison with homo-specific grafting of corresponding chick segments points to conservation in mouse and chick of the link between the patterning of activities and the axial origin of the hindbrain segment. This HF rhythm is reminiscent of the respiratory rhythm known to appear at E15 in mice. We also report on pre-/post-otic interactions. The pre-otic rhombomere 5 prevents the emergence of the HF rhythm at E12. Although the nature of the interaction with r5 remains obscure, we propose that ontogeny of fetal-like respiratory circuits relies on: (i) a selective developmental program enforcing HF rhythm generation, already set at E9 in post-otic segments, and (ii) trans-segmental interactions with pre-otic territories that may control the time when this rhythm appears.
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Affiliation(s)
- C Borday
- Neurobiologie Génétique et Intégrative, Institut de Neurobiologie Alfred Fessard, C.N.R.S., 1 av. de la Terrasse, 91198 Gif-sur-Yvette, France
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26
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Chatonnet F, Borday C, Wrobel L, Thoby-Brisson M, Fortin G, McLean H, Champagnat J. Ontogeny of central rhythm generation in chicks and rodents. Respir Physiol Neurobiol 2006; 154:37-46. [PMID: 16533622 DOI: 10.1016/j.resp.2006.02.004] [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: 11/23/2005] [Revised: 01/31/2006] [Accepted: 02/01/2006] [Indexed: 10/24/2022]
Abstract
Recent studies help in understanding how the basic organization of brainstem neuronal circuits along the anterior-posterior (AP) axis is set by the Hox-dependent segmentation of the neural tube in vertebrate embryos. Neonatal respiratory abnormalities in Krox20(-/-), Hoxa1(-/-) and kreisler mutant mice indicate the vital role of a para-facial (Krox20-dependent, rhombomere 4-derived) respiratory group, that is distinct from the more caudal rhythm generator called Pre-Bötzinger complex. Embryological studies in the chick suggest homology and conservation of this Krox20-dependent induction of parafacial rhythms in birds and mammals. Calcium imaging in embryo indicate that rhythm generators may derive from different cell lineages within rhombomeres. In mice, the Pre-Bötzinger complex is found to be distinct from oscillators producing the earliest neuronal activity, a primordial low-frequency rhythm. In contrast, in chicks, maturation of the parafacial generator is tightly linked to the evolution of this primordial rhythm. It seems therefore that ontogeny of brainstem rhythm generation involves conserved processes specifying distinct AP domains in the neural tube, followed by diverse, lineage-specific regulations allowing the emergence of organized rhythm generators at a given AP level.
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Affiliation(s)
- F Chatonnet
- UPR 2216, Neurobiologie Génétique et Integrative, Institut fédératif de Neurobiologie Alfred Fessard, C.N.R.S. 1, Avenue de la terrasse, Gif sur Yvette, 91198 Cedex, France
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27
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Gargaglioni LH, Milsom WK. Control of breathing in anuran amphibians. Comp Biochem Physiol A Mol Integr Physiol 2006; 147:665-684. [PMID: 16949847 DOI: 10.1016/j.cbpa.2006.06.040] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2006] [Revised: 06/21/2006] [Accepted: 06/24/2006] [Indexed: 11/27/2022]
Abstract
The primary role of the respiratory system is to ensure adequate tissue oxygenation, eliminate carbon dioxide and help to regulate acid-base status. To maintain this homeostasis, amphibians possess an array of receptors located at peripheral and central chemoreceptive sites that sense respiration-related variables in both internal and external environments. As in mammals, input from these receptors is integrated at central rhythmogenic and pattern-forming elements in the medulla in a manner that meets the demands determined by the environment within the constraints of the behavior and breathing pattern of the animal. Also as in mammals, while outputs from areas in the midbrain may modulate respiration directly, they do not play a significant role in the production of the normal respiratory rhythm. However, despite these similarities, the breathing patterns of the two classes are different: mammals maintain homeostasis of arterial blood gases through rhythmic and continuous breathing, whereas amphibians display an intermittent pattern of aerial respiration. While the latter is also often rhythmic, it allows a degree of fluctuation in key respiratory variables that has led some to suggest that control is not as tight in these animals. In this review we will focus specifically on recent advances in studies of the control of ventilation in anuran amphibians. This is the group of amphibians that has attracted the most recent attention from respiratory physiologists.
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Affiliation(s)
- Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, Sao Paulo State University-FCAV at Jaboticabal, SP, Brazil.
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
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28
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Thoby-Brisson M, Trinh JB, Champagnat J, Fortin G. Emergence of the pre-Bötzinger respiratory rhythm generator in the mouse embryo. J Neurosci 2006; 25:4307-18. [PMID: 15858057 PMCID: PMC6725099 DOI: 10.1523/jneurosci.0551-05.2005] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
To obtain insights into the emergence of rhythmogenic circuits supporting respiration, we monitored spontaneous activities in isolated brainstem and medullary transverse slice preparations of mouse embryos, combining electrophysiological and calcium imaging techniques. At embryonic day 15 (E15), in a restricted region ventral to the nucleus ambiguus, we observed the onset of a sustained high-frequency (HF) respiratory-like activity in addition to a preexisting low-frequency activity having a distinct initiation site, spatial extension, and susceptibility to gap junction blockers. At the time of its onset, the HF generator starts to express the neurokinin 1 receptor, is connected bilaterally, requires active AMPA/kainate glutamatergic synapses, and is modulated by substance P and the mu-opioid agonist D-Ala2-N-Me-Phe4-Glycol5-enkephalin. We conclude that a rhythm generator sharing the properties of the neonatal pre-Bötzinger complex becomes active during E15 in mice.
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Affiliation(s)
- Muriel Thoby-Brisson
- Laboratoire de Neurobiologie Génétique et Intégrative, Institut Alfred Fessard, Centre National de la Recherche Scientifique, 91198 Gif sur Yvette, France
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29
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Straka H, Baker R, Gilland E. Preservation of segmental hindbrain organization in adult frogs. J Comp Neurol 2006; 494:228-45. [PMID: 16320236 DOI: 10.1002/cne.20801] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
To test for possible retention of early segmental patterning throughout development, the cranial nerve efferent nuclei in adult ranid frogs were quantitatively mapped and compared with the segmental organization of these nuclei in larvae. Cranial nerve roots IV-X were labeled in larvae with fluorescent dextran amines. Each cranial nerve efferent nucleus resided in a characteristic segmental position within the clearly visible larval hindbrain rhombomeres (r). Trochlear motoneurons were located in r0, trigeminal motoneurons in r2-r3, facial branchiomotor and vestibuloacoustic efferent neurons in r4, abducens and facial parasympathetic neurons in r5, glossopharyngeal motoneurons in r6, and vagal efferent neurons in r7-r8 and rostral spinal cord. In adult frogs, biocytin labeling of cranial nerve roots IV-XII and spinal ventral root 2 in various combinations on both sides of the brain revealed precisely the same rostrocaudal sequence of efferent nuclei relative to each other as observed in larvae. This indicates that no longitudinal migratory rearrangement of hindbrain efferent neurons occurs. Although rhombomeres are not visible in adults, a segmental map of adult cranial nerve efferent nuclei can be inferred from the strict retention of the larval hindbrain pattern. Precise measurements of the borders of adjacent efferent nuclei within a coordinate system based on external landmarks were used to create a quantitative adult segmental map that mirrors the organization of the larval rhombomeric framework. Plotting morphologically and physiologically identified hindbrain neurons onto this map allows the physiological properties of adult hindbrain neurons to be linked with the underlying genetically specified segmental framework.
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Affiliation(s)
- Hans Straka
- Laboratoire de Neurobiologie des Réseaux Sensorimoteurs, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7060, Université Paris 5, Cédex 06, France.
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30
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Borday C, Chatonnet F, Thoby-Brisson M, Champagnat J, Fortin G. Neural tube patterning by Krox20 and emergence of a respiratory control. Respir Physiol Neurobiol 2005; 149:63-72. [PMID: 16203212 DOI: 10.1016/j.resp.2005.02.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2004] [Revised: 02/16/2005] [Accepted: 02/17/2005] [Indexed: 11/15/2022]
Abstract
Recent data begin to bridge the gap between developmental events controlling hindbrain neural tube regional patterning and the emergence of breathing behaviour in the fetus and its vital adaptive function after birth. In vertebrates, Hox paralogs and Hox-regulating genes orchestrate, in a conserved manner, the transient formation of developmental compartments in the hindbrain, the rhombomeres, in which rhythmic neuronal networks of the brainstem develop. Genetic inactivation of some of these genes in mice leads to pathological breathing at birth pointing to the vital importance of rhombomere 3 and 4 derived territories for maintenance of the breathing frequency. In chick embryo at E7, we investigated neuronal activities generated in neural tube islands deriving from combinations of rhombomeres isolated at embryonic day E1.5. Using a gain of function approach, we reveal a role of the transcription factor Krox20, specifying rhombomeres 3 and 5, in inducing a rhythm generator at the parafacial level of the hindbrain. The developmental genes selecting and regionally coordinating the fate of CNS progenitors may hold further clues to conserved aspects of neuronal network formation and function. However, the most immediate concern is to take advantage of early generated rhythmic activities in the hindbrain to pursue their downstream cellular and molecular targets, for it seems likely that it will be here that rhythmogenic properties will eventually take on a vital role at birth.
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Affiliation(s)
- C Borday
- UPR 2216 Neurobiologie Génétique et Integrative, Institut fédératif de Neurobiologie Alfred Fessard, C.N.R.S., 1, Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France
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31
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Pritz MB. Comparisons and homology in adult and developing vertebrate central nervous systems. BRAIN, BEHAVIOR AND EVOLUTION 2005; 66:222-33. [PMID: 16254412 DOI: 10.1159/000088127] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Comparisons of characters in both adult and developing vertebrate central nervous systems require an understanding of the concept of homology. This article begins with a definition of homology in adult animals and then discusses criteria and methodology used to make appropriate comparisons of characters at a variety of hierarchical levels. Crucial to such an analysis is the methodology employed by neurocladistics to ensure meaningful comparisons. Then, a similar approach is used to address these identical problems in embryos. Concerns unique to comparisons of developing central nervous systems are enumerated. In addition, a number of special features of central nervous system formation and organization in both adults and embryos are discussed within the framework of homology and neurocladistics. Lastly, the concept of field homology as applied to vertebrate central nervous system characters is addressed.
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Affiliation(s)
- Michael B Pritz
- Department of Neurological Surgery, Indiana University School of Medicine, 545 Barnhill Drive, EH 141, Indianapolis, IN 46202-5124, USA.
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32
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Moody WJ, Bosma MM. Ion Channel Development, Spontaneous Activity, and Activity-Dependent Development in Nerve and Muscle Cells. Physiol Rev 2005; 85:883-941. [PMID: 15987798 DOI: 10.1152/physrev.00017.2004] [Citation(s) in RCA: 274] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
At specific stages of development, nerve and muscle cells generate spontaneous electrical activity that is required for normal maturation of intrinsic excitability and synaptic connectivity. The patterns of this spontaneous activity are not simply immature versions of the mature activity, but rather are highly specialized to initiate and control many aspects of neuronal development. The configuration of voltage- and ligand-gated ion channels that are expressed early in development regulate the timing and waveform of this activity. They also regulate Ca2+influx during spontaneous activity, which is the first step in triggering activity-dependent developmental programs. For these reasons, the properties of voltage- and ligand-gated ion channels expressed by developing neurons and muscle cells often differ markedly from those of adult cells. When viewed from this perspective, the reasons for complex patterns of ion channel emergence and regression during development become much clearer.
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Affiliation(s)
- William J Moody
- Department of Biology, University of Washington, Seattle, Washington 98195, USA.
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33
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Coutinho AP, Borday C, Gilthorpe J, Jungbluth S, Champagnat J, Lumsden A, Fortin G. Induction of a parafacial rhythm generator by rhombomere 3 in the chick embryo. J Neurosci 2005; 24:9383-90. [PMID: 15496674 PMCID: PMC6730091 DOI: 10.1523/jneurosci.2408-04.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Observations of knock-out mice suggest that breathing at birth requires correct development of a specific hindbrain territory corresponding to rhombomeres (r) 3 and 4. Focusing on this territory, we examined the development of a neuronal rhythm generator in the chick embryo. We show that rhythmic activity in r4 is inducible after developmental stage 10 through interaction with r3. Although the nature of this interaction remains obscure, we find that the expression of Krox20, a segmentation gene responsible for specifying r3 and r5, is sufficient to endow other rhombomeres with the capacity to induce rhythmic activity in r4. Induction is robust, because it can be reproduced with r2 and r6 instead of r4 and with any hindbrain territory that normally expresses Krox20 (r3, r5) or can be forced to do so (r1, r4). Interestingly, the interaction between r4 and r3/r5 that results in rhythm production can only take place through the anterior border of r4, revealing a heretofore unsuspected polarity in individual rhombomeres. The r4 rhythm generator appears to be homologous to a murine respiratory parafacial neuronal system developing in r4 under the control of Krox20 and Hoxa1. These results identify a late role for Krox20 at the onset of neurogenesis.
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Affiliation(s)
- Ana P Coutinho
- Medical Research Council Centre for Developmental Neurobiology, King's College London, Guy's Campus, London SE1 1UL, United Kingdom
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34
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Tsunekawa N, Arata A, Obata K. Development of spontaneous mouth/tongue movement and related neural activity, and their repression in fetal mice lacking glutamate decarboxylase 67. Eur J Neurosci 2005; 21:173-8. [PMID: 15654854 DOI: 10.1111/j.1460-9568.2004.03860.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Spontaneous body movement starts at early fetal stage, at embryonic day (E) 12-15 in mice. In the present study, the movement of the head region was studied in E13-14 mice by in utero ultrasound imaging, together with the in vitro recording of underlying neural activities in the hypoglossal nerve and the ventral root of the upper cervical cord of an isolated brainstem-spinal cord preparation. The role of gamma-aminobutyric acid (GABA) in the generation of fetal movement was assessed using mice lacking GABA-synthesizing glutamate decarboxylase 67 (GAD67). At E14, mouth opening and tongue withdrawal were observed independently at frequency of 14/h each. This movement was rarely observed in the GAD67-deficient mouse. The intraventricular administration of picrotoxin or 3-mercaptopropionic acid abolished mouth opening in the wild-type mice. In a brainstem-spinal cord preparation, three types of neural discharge were recorded: mouth/tongue-moving burst, respiratory burst and irregular activity on the basis of their waveform, regularity in occurrence and concomitant muscle activity. In the GAD67-deficient mice, the occurrence of mouth/tongue-moving burst and irregular activity was inhibited to about 15 and 40% of those in the wild-type mice, respectively. Respiratory burst was slightly inhibited but the difference was not significant. Picrotoxin greatly reduced the frequency of mouth/tongue-moving burst. These results indicate that GABA is involved in rhythm generation in movement of the head region and support the hypothesis that cleft palate in the GAD67-deficient mouse is due to the impairment of mouth or tongue movement that assists palate formation.
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Affiliation(s)
- Naoko Tsunekawa
- Obata Research Unit, RIKEN Brain Science Institute, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan
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Fortin G, Borday C, Germon I, Champagnat J. Breathing at birth: influence of early developmental events. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2005; 551:143-8. [PMID: 15602956 DOI: 10.1007/0-387-27023-x_22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Affiliation(s)
- Gilles Fortin
- Neurobiologie Génétique et Integrative, Institut de Neurobiologie Alfred Fessard, CNRS, 91198, Gif sur Yvette, France
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36
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Lumsden A. Segmentation and compartition in the early avian hindbrain. Mech Dev 2005; 121:1081-8. [PMID: 15296973 DOI: 10.1016/j.mod.2004.04.018] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2004] [Revised: 04/19/2004] [Accepted: 04/26/2004] [Indexed: 11/16/2022]
Abstract
For the comparative embryologists of the early 20th century, the segment-like bulges that appear transiently during the early stages of vertebrate hindbrain development were both the object of fascination and the subject of vigorous dispute. Conflicting views were held as to the significance of these 'rhombomeres' to brain development and their more general relevance to head evolution. Whether rhombomeres are inconsequential bumps in the embryonic brain or true segments-iterative or metameric units-has only recently been resolved. A number of studies using more modern techniques (such as immunohistochemistry, in situ hybridisation, axonal tracing, single cell labelling, heterotopic and orthotopic grafting, and the manipulation of gene expression by electroporation) have shown that the hindbrain has a truly metameric cellular organisation. The avian embryo has played a particularly prominent role in such studies by virtue of its large size and accessibility, its amenability to microsurgery, and its well-described anatomy. Furthermore, electrophysiological studies, also on avian embryos, have shown that segmentation of the parent neuroepithelium into rhombomeres plays a crucial part in establishing the functional organization of the hindbrain. Segmentation suggests the early allocation of defined sets of precursor cells and is therefore presumed to allow a specific identity for each successive segment to emerge from a common ground plan. This short review will focus on the contribution the avian embryo has made to our understanding of this fly-like region of the vertebrate brain, in respect of its morphology and neuronal architecture, the cellular and molecular mechanisms involved in establishing and maintaining the segments, and the molecular controls of segmental identity.
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Affiliation(s)
- Andrew Lumsden
- MRC Centre for Developmental Neurobiology, King's College London, Guy's Hospital Campus, London SE1 1UL, UK.
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Borday C, Wrobel L, Fortin G, Champagnat J, Thaëron-Antôno C, Thoby-Brisson M. Developmental gene control of brainstem function: views from the embryo. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2004; 84:89-106. [PMID: 14769431 DOI: 10.1016/j.pbiomolbio.2003.11.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The respiratory rhythm is generated within the hindbrain reticular formation, rostrally in the vicinity of the facial nucleus and caudally within the vagal/glossopharyngeal domain. This is probably one of the best models to understand how genes have been selected and conserved to control adaptive behaviour in vertebrates. The para-facial region is well understood with respect to the transcription factors that underlie antero-posterior specification of neural progenitors in the embryo. Hox paralogs and Hox-regulating genes kreisler and Krox-20 govern transient formation of developmental compartments, the rhombomeres, in which rhythmic neuronal networks develop. Hox are master genes selecting and coordinating the developmental fate of reticular and motor neurons thereby specifying patterns of motor activities operating throughout life. Neuronal function and development are also tightly linked in the vagal/glossopharyngeal domain. At this level, bdnf acts as a neurotrophin of peripheral chemoafferent neural populations and as a neuromodulator of the central rhythmogenic respiratory circuits. A general view is now emerging on the role of developmental transcription and trophic factors allowing the coordinated integration of different neuronal types to produce, and eventually refine, respiratory rhythmic pattern in a use-dependent manner.
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Affiliation(s)
- Caroline Borday
- UPR 2216 Neurobiologie Génétique et Intégrative, Institut de Neurobiologie Alfred Fessard, CNRS, 1, av de la Terrasse, Gif-sur-Yvette 91198, France
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38
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Abstract
Respiratory neuronal networks in vertebrates appear to be able to generate a variety of rhythmic patterns in vivo, leading to the biological diversity of eupneic patterns as well as to life-threatening dyspneic patterns. Eupnea is best viewed as the collection of respiratory strategies preventing potential dyspneas, the major (and perhaps the only) criterion for a definition being that eupnea allows survival. Specific criteria can then be derived from the physiological identification of neurobiological mechanisms underlying identified dyspneic patterns, by exaggerating (pro-dyspneic mechanisms) or suppressing them (anti-dyspneic mechanisms). Because eupnea is vital, and one of the major targets of evolutionary pressure, identification of dyspnea-related neuronal systems seems to be important to understand the normal biological organization of the respiratory neuronal system.
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Affiliation(s)
- Jean Champagnat
- U.P.R. 2216, Neurobiologie Génétique et Intégrative, IFR 2118 Institut de Neurobiologie Alfred Fessard, C.N.R.S., 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France.
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Kuwana S, Okada Y, Sugawara Y, Tsunekawa N, Obata K. Disturbance of neural respiratory control in neonatal mice lacking GABA synthesizing enzyme 67-kDa isoform of glutamic acid decarboxylase. Neuroscience 2003; 120:861-70. [PMID: 12895526 DOI: 10.1016/s0306-4522(03)00338-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
To examine the role of GABA in the respiratory rhythm and pattern generation in neonatal mice, we analyzed the function of the respiratory control system of 67-kDa isoform of glutamic acid decarboxylase (GAD67)-deficient neonatal mice. In these mutant (GAD67-/-) mice, GABA levels in the brainstem were reduced to about 30% of those in wild-type (GAD67+/+) mice. In in vivo preparations, ventilatory parameters were analyzed by whole body plethysmography and electromyography of intercostal muscles. GAD67-/- mice exhibited abnormal respiratory patterns, i.e. irregular respiratory rhythm, and periodic gasp-like respiration followed by shallow breathing with short inspiratory duration and apnea. In in vitro GAD67-/- brainstem-spinal cord preparations, inspiratory C4 burst duration was shorter than that in GAD67+/+ preparations. Whole cell recordings revealed that activities of inspiratory neurons in the ventral medulla of GAD67-/- mice were characterized by a short depolarization period and a paucity of firing during the inspiratory phase. Superfusion of the in vitro GAD67-/- preparation with 10 microM GABA prolonged C4 burst duration and partly restored a normal pattern of inspiration, although the restoration was limited. These results indicate that reduced GABA levels during the perinatal period induce malfunction in the respiratory control system. We suggest that GABAergic transmission is not essential for basic respiratory rhythm generation but plays an important role in the maintenance of regular respiratory rhythm and normal inspiratory pattern in neonatal mice.
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Affiliation(s)
- S Kuwana
- Department of Physiology, Teikyo University School of Medicine, Kaga 2-11-1, Itabashi-ku, Tokyo 173-8605, Japan.
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Expression of functional tyrosine kinase B receptors by rhythmically active respiratory neurons in the pre-Bötzinger complex of neonatal mice. J Neurosci 2003. [PMID: 12930808 DOI: 10.1523/jneurosci.23-20-07685.2003] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Genetic loss of brain-derived neurotrophic factor (BDNF) severely disrupts brainstem control of respiratory rhythmogenesis in newborn mice; however, the sites at which BDNF acts to regulate respiratory rhythmogenesis are unknown. Using immunochemical and multiplex RT-PCR analysis in mouse brainstem slices, we report that the BDNF receptor, Tyrosine kinase B (TrkB), is strongly expressed in the pre-Bötzinger complex (PBC), the presumed site for rhythm generation, and colocalizes with neurokinin 1 (NK1), a marker of neurons critical for breathing. The period of the respiratory rhythm generated by PBC neurons in vitro was increased by 30% after BDNF treatment (100 ng/ml) and not by nerve growth factor (100 ng/ml) or BDNF (100 ng/ml) in the presence of the tyrosine kinase inhibitor K252a (200 nm). Both synaptic and voltage-dependent properties of PBC neurons were modified by BDNF. Synaptic currents underlying spontaneous rhythmic bursts and glutamate-evoked currents were enhanced by 66 and 33%, respectively. BDNF reduced the Ih current amplitude in rhythmic neurons by 46% and shifted its activation curve by -17 mV. All neurons expressing TrkB mRNA (n = 8) also expressed mRNAs for the Ih current [hyperpolarization-activated cyclic nucleotide-sensitive cation nonselective channel (HCN1)], and three of four NK1-positive neurons coexpressed TrkB and HCN mRNA. Six of 16 PBC neurons expressed BDNF mRNA, supporting the possibility of autocrine and paracrine actions of BDNF within the respiratory pattern generator. Our data demonstrate that BDNF can modulate respiratory network activity through TrkB signaling in rhythmic PBC neurons.
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Fortin G, Charnay P, Champagnat J. Linking respiratory rhythm generation to segmentation of the vertebrate hindbrain. Pflugers Arch 2003; 446:514-5. [PMID: 12728321 DOI: 10.1007/s00424-003-1083-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2003] [Accepted: 03/24/2003] [Indexed: 10/26/2022]
Affiliation(s)
- Gilles Fortin
- Neurobiologie Génétique et Intégrative, UPR2216, Centre National de la Recherche Scientifique, Institut de Neurobiologie Alfred Fessard UFR 2218, 91198 Gif-sur-Yvette Cedex, France
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Borday C, Abadie V, Chatonnet F, Thoby-Brisson M, Champagnat J, Fortin G. Developmental molecular switches regulating breathing patterns in CNS. Respir Physiol Neurobiol 2003; 135:121-32. [PMID: 12809613 DOI: 10.1016/s1569-9048(03)00031-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The present paper presents some of the molecular switches that may operate at early embryonic stages to make development of the brainstem respiratory rhythm generator a robust and irreversible process. We concentrate on the role of transient Hox-related gene expression patterns in register with the regionalisation of the rhombencephalic neural tube along the antero-posterior axis. Using different recording and isolation procedures in chick embryos, we show that the hindbrain is subdivided at E1 into developmental units (rhombomeres) intrinsically able to produce rhythm generating neuronal circuits active at E5. At E6, intrinsic cues also allow a progressive maturation of episodic rhythm generators that persists after isolation of the hindbrain in vitro and requires odd/even rhombomeric interactions at E1. From these results and from respiratory pathologies observed in transgenic mice, we are beginning to understand that, despite diversity of breathing patterns and adaptations, there are links between developmental control genes and adult respiration.
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Affiliation(s)
- Caroline Borday
- UPR 2216 Neurobiologie Génétique et Intégrative, Institut de Neurobiologie Alfred Fessard, C.N.R.S., 1, av. de la Terrasse, 91198, Gif-sur-Yvette, France.
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43
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Daz C, Puelles L. Plurisegmental vestibulocerebellar projections and other hindbrain cerebellar afferents in midterm chick embryos: biotinylated dextranamine experiments in vitro. Neuroscience 2003; 117:71-82. [PMID: 12605894 DOI: 10.1016/s0306-4522(02)00834-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The vestibular neuronal groups that project to the cerebellum were mapped in midterm chick embryos (10-11 days in "ovo") through "in vitro " retrograde tracing experiments. Massive unilateral deposits of biotin-dextranamine were placed at the basis of the cerebellum to label the cerebellar peduncles. Separate rostral and caudal vestibulo-cerebellar groups were identified, with predominance of contralateral neurons. We tentatively identified the rhombomeric location of both groups, as well as their topography within the conventional cytoarchitectonically-defined vestibular nuclei, by comparison with previously established segmental fate maps. The rostral group extended from rhombomeres 1-4 (r1-r4) and was restricted mainly to the superior vestibular nucleus. The caudal group stretched from r6 to pseudorhombomere "r8" and was related to the descending and medial vestibular nuclei. The less abundant ipsilateral vestibulocerebellar neurons had a similar topography. The crossing axons of the rostral vestibulocerebellar neurons formed a distinct rostral vestibulocerebellar decussation, restricted to the floorplate of rhombomere 2. The axons of the caudal vestibulocerebellar population mostly decussated associated to the deep cochlear commissure. The present results extend the "segmental hodological mosaic" of defined projection-neuron groups identified within the avian vestibular nuclear complex: The vestibulocerebellar projecting neurons as a type appear iterated from r1 to r4 and from r6 to pseudorhombomere "r8," albeit showing in their arrangement peculiarities related to single segmental domains, particularly rostrally. In contrast, the vestibulospinal groups are located more restrictedly in r4-r6, while the vestibulo-ocular projecting neurons extend from r1 to "r7." Only r4 and r6 contain elements of all three hodological types. The organization of the three vestibular projection populations studied to date seems comparable in chicken and frogs and may be a conserved feature in vertebrates.
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Affiliation(s)
- C Daz
- Department of Morphological Sciences, Faculty of Medicine, University of Murcia, Spain.
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44
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Momose-Sato Y, Mochida H, Sasaki S, Sato K. Depolarization waves in the embryonic CNS triggered by multiple sensory inputs and spontaneous activity: optical imaging with a voltage-sensitive dye. Neuroscience 2003; 116:407-23. [PMID: 12559096 DOI: 10.1016/s0306-4522(02)00585-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Previously, we discovered a novel type of depolarization wave in the embryonic chick brain by using a multiple-site optical recording technique with a fast voltage-sensitive dye. This depolarization wave traveled widely over almost all the region of the CNS. This profile has raised the possibility that the depolarization wave plays some global roles in development of the CNS, rather than contributing to a specific neuronal circuit formation. To obtain more information concerning this issue, in the present study, we examined whether the depolarization wave was triggered by various types of peripheral nerve inputs. Stimulation applied to the vagus, glossopharyngeal, cochlear and trigeminal nerves evoked widely spreading depolarization waves with similar spatiotemporal distribution patterns. The developmental sequence of wave expression was parallel to the development of the excitatory postsynaptic potentials in each sensory nucleus. The depolarization wave was accompanied by a Ca(2+)-wave, suggesting that not only electrical synchrony, but also large-scale Ca(2+)-transients may affect developmental processes in the embryonic brain. Furthermore, we found that the depolarization wave also occurred spontaneously. The waveform and distribution patterns of the spontaneous optical signals were similar to those of the cranial nerve-evoked depolarization wave. These results demonstrated that the depolarization wave in the embryonic chick brain is triggered by multiple sources of external and endogenous activity. This profile supports the idea that this depolarization wave may not serve as a simple regulator of specific neuronal circuit formation, but might play more global roles in CNS development.
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Affiliation(s)
- Y Momose-Sato
- Department of Physiology, Tokyo Medical and Dental University, Graduate School and Faculty of Medicine, Bunkyo-ku, Tokyo 113-8519, Japan.
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45
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Momose-Sato Y, Miyakawa N, Mochida H, Sasaki S, Sato K. Optical analysis of depolarization waves in the embryonic brain: a dual network of gap junctions and chemical synapses. J Neurophysiol 2003; 89:600-14. [PMID: 12522205 DOI: 10.1152/jn.00337.2002] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Correlated neuronal activity plays a fundamental role in the development of the CNS. Using a multiple-site optical recording technique with a voltage-sensitive dye, we previously described a novel type of depolarization wave that was evoked by cranial or spinal nerve stimulation and spread widely over the whole brain region in the chick embryo. We have now investigated developmental expression and neuronal network mechanisms of this depolarization wave by applying direct stimulation to the brain stem or upper cervical cord of E5-E11 embryos, which elicited wave activity similar to that evoked by nerve stimulation. Spatial distribution patterns of the depolarization wave changed dynamically with development, and this change appeared to be related to the regional differences in neuronal differentiation. The depolarization wave was completely eliminated by application of either gap junction blockers or an N-methyl-D-aspartate (NMDA)-receptor antagonist, indicating that functions of both gap junctions and NMDA receptors are indispensable for wave propagation. A possible interpretation of the results is that dual networks of gap junctions and chemical synaptic coupling mediate large-scale depolarization waves in the developing chick CNS.
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Affiliation(s)
- Yoko Momose-Sato
- Department of Physiology, Tokyo Medical and Dental University, Graduate School and Faculty of Medicine, Japan.
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Chatonnet F, Thoby-Brisson M, Abadie V, Domínguez del Toro E, Champagnat J, Fortin G. Early development of respiratory rhythm generation in mouse and chick. Respir Physiol Neurobiol 2002; 131:5-13. [PMID: 12106991 DOI: 10.1016/s1569-9048(02)00033-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We are investigating neuronal circuits resulting from conservative developmental mechanisms orchestrating the segmentation of the vertebrates hindbrain into compartments called rhombomeres (r). Segmentation transcription factors Hoxa1, Krox20 and kreisler are expressed in the future rhombomeres r4-r5, r3 and r5, r5-r6, respectively. In mice, the in vivo and in vitro analysis of neuronal groups after inactivation of these three genes revealed distinct postnatal respiratory phenotypes associated with defects of central respiratory controls resulting from deletion, neoformation or reconfiguration of modular circuits. In chick and mice, we have found neuronal rhythm generators that conform to the rhombomeric anatomical pattern as early as at the end of the segmentation. By isolating chick hindbrain segments in vitro, we have also identified rhombomeric motifs allowing the formation or deletion of a specific (GABAergic) rhythm-promoting module. Therefore, primordial rhombomeric organization of the hindbrain seems to determine a modular organization of the rhythmogenic network, thereby influencing later function of brainstem respiratory control networks.
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Affiliation(s)
- Fabrice Chatonnet
- U.P.R. 2216, Neurobiologie Génétique et Intégrative, IFR 2118 Institut de Neurobiologie Alfred Fessard, C.N.R.S., 1, av. de la Terrasse, 91198 Gif-sur-Yvette, France.
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Wilson RJA, Vasilakos K, Harris MB, Straus C, Remmers JE. Evidence that ventilatory rhythmogenesis in the frog involves two distinct neuronal oscillators. J Physiol 2002; 540:557-70. [PMID: 11956343 PMCID: PMC2290235 DOI: 10.1113/jphysiol.2001.013512] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
In Rana catesbeiana the upper airways are used for two distinct yet highly coordinated ventilatory behaviours: buccal ventilation and lung inflation cycles. How these behaviours are generated and coordinated is unknown. The purpose of this study was to identify putative rhythmogenic brainstem loci involved in these ventilatory behaviours. We surveyed the isolated postmetamorphic brainstem to determine sites where local depolarization, produced by microinjecting the non-NMDA glutamate receptor agonist, AMPA, augmented the ventilatory motor patterns. Two sites were identified: a caudal site, at the level of cranial nerve (CN) X, where AMPA injections caused increased buccal burst frequency but abolished lung bursts, and a rostral site, between the levels of CN VIII and IX, where injections increased the frequency of both types of ventilatory bursts. These two sites were further examined using GABA microinjections to locally inhibit cells. GABA injected into the caudal site suppressed the buccal rhythm but the lung rhythm continued, albeit at a different frequency. When GABA was injected into the rostral site the lung bursts were abolished but the buccal rhythm continued. When the two sites were physically separated by transection, both rostral and caudal brainstem sections were capable of rhythmogenesis. The results suggest the respiratory network within the amphibian brainstem is composed of at least two distinct but interacting oscillators, the buccal and lung oscillators. These putative oscillators may provide a promising experimental model for studying coupled oscillators in vertebrates.
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Affiliation(s)
- R J A Wilson
- Department of Medical Physiology, University of Calgary, 330 Hospital Drive, N.W., Calgary, Alberta, Canada T2N 4N1.
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48
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Descending 5-hydroxytryptamine raphe inputs repress the expression of serotonergic neurons and slow the maturation of inhibitory systems in mouse embryonic spinal cord. J Neurosci 2002. [PMID: 11923425 DOI: 10.1523/jneurosci.22-07-02598.2002] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Spontaneous synchronous rhythmic activities are a common feature of immature neuronal networks. Although the mechanisms underlying such activities have been studied extensively, whether they might be controlled by modulatory information remains questionable. Here, we investigated the role of descending serotonergic (5-HT) inputs from the medulla to the spinal cord in the maturation of rhythmic activity. We found that in spinal cords maintained, as a whole, in organotypic culture without the medulla, the maturation of spontaneous activity is similar to that found in spinal cords developed in utero. Interestingly, in organotypic cultures without the medulla (i.e., devoid of descending inputs), numerous intraspinal neurons expressed 5-HT, unlike in spinal cords cultivated in the presence of the medulla or matured in utero. We demonstrated that this 5-HT expression was specifically dependent on the absence of 5-HT fibers and was repressed by 5-HT itself via activation of 5-HT(1A) receptors. Finally, to verify whether the expression of 5-HT intraspinal neurons could compensate for the lack of descending 5-HT fibers and play a role in the development of spontaneous activity, we blocked the 5-HT synthesis using p-chlorophenylalanine methyl ester in cultures devoid of the medulla. Surprisingly, we found that this pharmacological treatment did not prevent the development of spontaneous activity but accelerated the maturation of intraspinal inhibition at the studied stages. Together, our data indicate that descending 5-HT raphe inputs (1) repress the expression of spinal serotonergic neurons and (2) slow the maturation of inhibitory systems in mouse spinal cord.
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Jungbluth S, Willecke K, Champagnat J. Segment-specific expression of connexin31 in the embryonic hindbrain is regulated by Krox20. Dev Dyn 2002; 223:544-51. [PMID: 11921342 DOI: 10.1002/dvdy.10072] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Communication and interaction between cells has been shown to be important during the embryonic development of the vertebrate hindbrain, which becomes transiently subdivided into segments called rhombomeres (r). One gene family allowing intercellular communication and possibly being involved in the control of hindbrain development is the connexin family encoding gap junction channels. Here, we have characterized in detail the previously observed (Dahl et al., 1997) expression of one particular connexin gene, connexin31 (Cx31), in the mouse embryonic hindbrain and compared it with that of Cx43 and Cx36. We found transient Cx31 expression from approximately embryonic day (E) E8-E11 in two small lateral/dorsal subgroups of cells in the hindbrain. We could show that these spots of expression corresponded to r3 and r5 and that Cx31 expression in r3 and r5 was controlled by the transcription factor Krox20. In contrast, expression of Cx43 and Cx36 started later (from E9.5 and E10.5, respectively) and was confined to longitudinal stripes of expression. In addition, from E10.5-E11.5, Cx31 was expressed by a column of cells in ventral r4, most likely representing contralateral vestibulo-acoustic efferent neurons, immediately anterior to a ventral column expressing Cx36 at the same stage. From E11.5 onward, another site of Cx31 expression was detected in the boundary cap cells in the entry/exit points of all mixed sensory/motor and in the entry points of pure sensory nerves. This expression was not present in the boundary cap cells of the exit points of pure motor nerves. So far, our analysis of the hindbrain area of Cx31-deficient embryos in terms of projections of sensory or motor neurons or in the generation or migration of neurons has not yet revealed any obvious defects.
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Affiliation(s)
- Stefan Jungbluth
- Neurobiologie Genetique et Integrative, Institut de Neurobiologie Alfred Fessard, CNRS, Gif-sur-Yvette, France.
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50
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Corner MA, van Pelt J, Wolters PS, Baker RE, Nuytinck RH. Physiological effects of sustained blockade of excitatory synaptic transmission on spontaneously active developing neuronal networks--an inquiry into the reciprocal linkage between intrinsic biorhythms and neuroplasticity in early ontogeny. Neurosci Biobehav Rev 2002; 26:127-85. [PMID: 11856557 DOI: 10.1016/s0149-7634(01)00062-8] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Spontaneous bioelectric activity (SBA) taking the form of extracellularly recorded spike trains (SBA) has been quantitatively analyzed in organotypic neonatal rat visual cortex explants at different ages in vitro, and the effects investigated of both short- and long-term pharmacological suppression of glutamatergic synaptic transmission. In the presence of APV, a selective NMDA receptor blocker, 1-2- (but not 3-)week-old cultures recovered their previous SBA levels in a matter of hours, although in imitation of the acute effect of the GABAergic inhibitor picrotoxin (PTX), bursts of action potentials were abnormally short and intense. Cultures treated either overnight or chronically for 1-3 weeks with APV, the AMPA/kainate receptor blocker DNQX, or a combination of the two were found to display very different abnormalities in their firing patterns. NMDA receptor blockade for 3 weeks produced the most severe deviations from control SBA, consisting of greatly prolonged and intensified burst firing with a strong tendency to be broken up into trains of shorter spike clusters. This pattern was most closely approximated by acute GABAergic disinhibition in cultures of the same age, but this latter treatment also differed in several respects from the chronic-APV effect. In 2-week-old explants, in contrast, it was the APV+DNQX treated group which showed the most exaggerated spike bursts. Functional maturation of neocortical networks, therefore, may specifically require NMDA receptor activation (not merely a high level of neuronal firing) which initially is driven by endogenous rather than afferent evoked bioelectric activity. Putative cellular mechanisms are discussed in the context of a thorough review of the extensive but scattered literature relating activity-dependent brain development to spontaneous neuronal firing patterns.
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Affiliation(s)
- M A Corner
- Academic Medical Centre, Meibergdreef 33, Netherlands Institute for Brain Research, 1105 AZ Amsterdam, The Netherlands.
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