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Lucas JA, Schmidt TM. Cellular properties of intrinsically photosensitive retinal ganglion cells during postnatal development. Neural Dev 2019; 14:8. [PMID: 31470901 PMCID: PMC6716945 DOI: 10.1186/s13064-019-0132-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 08/12/2019] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Melanopsin-expressing, intrinsically photosensitive retinal ganglion cells (ipRGCs) respond directly to light and have been shown to mediate a broad variety of visual behaviors in adult animals. ipRGCs are also the first light sensitive cells in the developing retina, and have been implicated in a number of retinal developmental processes such as pruning of retinal vasculature and refinement of retinofugal projections. However, little is currently known about the properties of the six ipRGC subtypes during development, and how these cells act to influence retinal development. We therefore sought to characterize the structure, physiology, and birthdate of the most abundant ipRGC subtypes, M1, M2, and M4, at discrete postnatal developmental timepoints. METHODS We utilized whole cell patch clamp to measure the electrophysiological and morphological properties of ipRGC subtypes through postnatal development. We also used EdU labeling to determine the embryonic timepoints at which ipRGC subtypes terminally differentiate. RESULTS Our data show that ipRGC subtypes are distinguishable from each other early in postnatal development. Additionally, we find that while ipRGC subtypes terminally differentiate at similar embryonic stages, the subtypes reach adult-like morphology and physiology at different developmental timepoints. CONCLUSIONS This work provides a broad assessment of ipRGC morphological and physiological properties during the postnatal stages at which they are most influential in modulating retinal development, and lays the groundwork for further understanding of the specific role of each ipRGC subtype in influencing retinal and visual system development.
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Affiliation(s)
- Jasmine A. Lucas
- Department of Neurobiology, Northwestern University, Evanston, IL USA
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Nishino A. Morphology and Physiology of the Ascidian Nervous Systems and the Effectors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018. [PMID: 29542090 DOI: 10.1007/978-981-10-7545-2_16] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurobiology in ascidians has made many advances. Ascidians have offered natural advantages to researchers, including fecundity, structural simplicity, invariant morphology, and fast and stereotyped developmental processes. The researchers have also accumulated on this animal a great deal of knowledge, genomic resources, and modern genetic techniques. A recent connectomic analysis has shown an ultimately resolved image of the larval nervous system, whereas recent applications of live imaging and optogenetics have clarified the functional organization of the juvenile nervous system. Progress in resources and techniques have provided convincing ways to deepen what we have wanted to know about the nervous systems of ascidians. Here, the research history and the current views regarding ascidian nervous systems are summarized.
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Affiliation(s)
- Atsuo Nishino
- Department of Biology, Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori, Japan.
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Sarantopoulos CD, McCallum JB, Rigaud M, Fuchs A, Kwok WM, Hogan QH. Opposing effects of spinal nerve ligation on calcium-activated potassium currents in axotomized and adjacent mammalian primary afferent neurons. Brain Res 2007; 1132:84-99. [PMID: 17184741 PMCID: PMC2692681 DOI: 10.1016/j.brainres.2006.11.055] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Revised: 11/09/2006] [Accepted: 11/09/2006] [Indexed: 10/23/2022]
Abstract
UNLABELLED Calcium-activated potassium channels regulate AHP and excitability in neurons. Since we have previously shown that axotomy decreases I(Ca) in DRG neurons, we investigated the association between I(Ca) and K((Ca)) currents in control medium-sized (30-39 microM) neurons, as well as axotomized L5 or adjacent L4 DRG neurons from hyperalgesic rats following L5 SNL. Currents in response to AP waveform voltage commands were recorded first in Tyrode's solution and sequentially after: 1) blocking Na(+) current with NMDG and TTX; 2) addition of K((Ca)) blockers with a combination of apamin 1 microM, iberiotoxin 200 nM, and clotrimazole 500 nM; 3) blocking remaining K(+) current with the addition of 4-AP, TEA-Cl, and glibenclamide; and 4) blocking I(Ca) with cadmium. In separate experiments, currents were evoked (HP -60 mV, 200 ms square command pulses from -100 to +50 mV) while ensuring high levels of activation of I(K(Ca)) by clamping cytosolic Ca(2+) concentration with pipette solution in which Ca(2+) was buffered to 1 microM. This revealed I(K(Ca)) with components sensitive to apamin, clotrimazole and iberiotoxin. SNL decreases total I(K(Ca)) in axotomized (L5) neurons, but increases total I(K(Ca)) in adjacent (L4) DRG neurons. All I(K(Ca)) subtypes are decreased by axotomy, but iberiotoxin-sensitive and clotrimazole-sensitive current densities are increased in adjacent L4 neurons after SNL. In an additional set of experiments we found that small-sized control DRG neurons also expressed iberiotoxin-sensitive currents, which are reduced in both axotomized (L5) and adjacent (L4) neurons. CONCLUSIONS Axotomy decreases I(K(Ca)) due to a direct effect on K((Ca)) channels. Axotomy-induced loss of I(Ca) may further potentiate current reduction. This reduction in I(K(Ca)) may contribute to elevated excitability after axotomy. Adjacent neurons (L4 after SNL) exhibit increased I(K(Ca)) current.
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MESH Headings
- Animals
- Axotomy
- Calcium/metabolism
- Calcium Signaling/drug effects
- Calcium Signaling/physiology
- Cell Size/drug effects
- Cells, Cultured
- Ganglia, Spinal/cytology
- Ganglia, Spinal/metabolism
- Ganglia, Spinal/physiopathology
- Hyperalgesia/metabolism
- Hyperalgesia/physiopathology
- Ligation
- Male
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Neurons, Afferent/cytology
- Neurons, Afferent/drug effects
- Neurons, Afferent/metabolism
- Organ Culture Techniques
- Patch-Clamp Techniques
- Peripheral Nervous System Diseases/metabolism
- Peripheral Nervous System Diseases/physiopathology
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Calcium-Activated/drug effects
- Potassium Channels, Calcium-Activated/metabolism
- Rats
- Rats, Sprague-Dawley
- Sciatic Neuropathy/metabolism
- Sciatic Neuropathy/physiopathology
- Sodium Channel Blockers/pharmacology
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Affiliation(s)
- Constantine D Sarantopoulos
- Department of Anesthesiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
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McCabe AK, Easton CR, Lischalk JW, Moody WJ. Roles of glutamate and GABA receptors in setting the developmental timing of spontaneous synchronized activity in the developing mouse cortex. Dev Neurobiol 2007; 67:1574-88. [PMID: 17542015 DOI: 10.1002/dneu.20533] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Spontaneous, synchronized electrical activity (SSA) plays important roles in nervous system development, but it is not clear what causes it to start and stop at the appropriate times. In previous work, we showed that when SSA in neonatal mouse cortex is blocked by TTX in cultured slices during its normal time of occurrence (E17-P3), it fails to stop at P3 as it does in control cultured slices, but instead persists through at least P10. This indicates that SSA is self-extinguishing. Here we use whole-cell recordings and [Ca2+]i imaging to compare control and TTX-treated slices to isolate the factors that normally extinguish SSA on schedule. In TTX-treated slices, SSA bursts average 4 s in duration, and have two components. The first, lasting about 1 s, is mediated by AMPA receptors; the second, which extends the burst to 4 s and is responsible for most of the action potential generation during the burst, is mediated by NMDA receptors. In later stage (P5-P9) control slices, after SSA has declined to about 4% of its peak frequency, bursts lack this long NMDA component. Blocking this NMDA component in P5-P9 TTX-treated slices reduces SSA frequency, but not to the low values found in control slices, implying that additional factors help extinguish SSA. GABA(A) inhibitors restore SSA in control slices, indicating that the emergence of GABA(A)-mediated inhibition is another major factor that helps terminate SSA.
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Affiliation(s)
- Annette K McCabe
- Department of Biology, University of Washington, Seattle, Washington 98195, USA
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McCabe AK, Chisholm SL, Picken-Bahrey HL, Moody WJ. The self-regulating nature of spontaneous synchronized activity in developing mouse cortical neurones. J Physiol 2006; 577:155-67. [PMID: 16945966 PMCID: PMC2000675 DOI: 10.1113/jphysiol.2006.117523] [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] [Indexed: 11/08/2022] Open
Abstract
Waves of spontaneous electrical activity that are highly synchronized across large populations of neurones occur throughout the developing mammalian central nervous system. The stages at which this activity occurs are tightly regulated to allow activity-dependent developmental programmes to be initiated correctly. What determines the onset and cessation of spontaneous synchronous activity (SSA) in a particular region of the nervous system, however, remains unclear. We have tested the hypothesis that activity itself triggers developmental changes in intrinsic and circuit properties that determine the stages at which SSA occurs. To do this we exposed cultured slices of mouse neocortex to tetrodotoxin (TTX) to block SSA, which normally occurs between embryonic day 17 (E17) and postnatal day 3 (P3). In control cultured slices, SSA rarely occurs after P3. In TTX-treated slices, however, SSA was generated from P3 (the day of TTX removal) until at least P10. This indicates that in the absence of spontaneous activity, the mechanisms that normally determine the timing of SSA are not initiated, and that a compensatory response occurs that shifts the time of SSA occurrence to later developmental stages.
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Affiliation(s)
- Annette K McCabe
- Department of Biology, University of Washington, Seattle, WA 98195, USA
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Ohtsuka Y, Okamura Y. Voltage-dependent calcium influx mediates maturation of myofibril arrangement in ascidian larval muscle. Dev Biol 2006; 301:361-73. [PMID: 16962575 DOI: 10.1016/j.ydbio.2006.08.013] [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] [Received: 05/10/2006] [Revised: 07/28/2006] [Accepted: 08/04/2006] [Indexed: 11/18/2022]
Abstract
Calcium signaling is important for multiple events during embryonic development. However, roles of calcium influx during embryogenesis have not been fully understood since routes of calcium influx are often redundant. To define roles of voltage-gated calcium channel (Cav) during embryogenesis, we have isolated an ascidian Cav beta subunit gene (TuCavbeta) and performed gene knockdown using the morpholino antisense oligonucleotide (MO). The suppression of Cav activity by TuCavbetaMO remarkably perturbed gastrulation and tail elongation. Further, larvae with normal morphology also failed to exhibit motility. Phalloidin-staining showed that arrangement of myofibrils was uncoordinated in muscle cells of TuCavbetaMO-injected larvae with normal tail. To further understand the roles of Cav activity in myofibrillogenesis, we tested pharmacological inhibitions with ryanodine, curare, and N-benzyl-p-toluensulphonamide (BTS). The treatment with ryanodine, an intracellular calcium release blocker, did not significantly affect the motility and establishment of the myofibril orientation. However, treatment with curare, an acetylcholine receptor blocker, and BTS, an actomyosin ATPase specific inhibitor, led to abnormal motility and irregular orientation of myofibrils that was similar to those of TuCavbetaMO-injected larvae. Our results suggest that contractile activation regulated by voltage-dependent calcium influx but not by intracellular calcium release is required for proper arrangement of myofibrils.
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Affiliation(s)
- Yukio Ohtsuka
- Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 6, Higashi 1-1-1, Tsukuba, Ibaraki 305-8566, Japan.
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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: 281] [Impact Index Per Article: 14.8] [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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Moody WJ. Subtype-specific mechanisms for regulating K+ channel density during development. Focus on "The carboxyl tail region of the Kv2.2 subunit mediates novel developments of channel density". J Neurophysiol 2004; 92:3169-70. [PMID: 15548633 DOI: 10.1152/jn.00795.2004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Corlew R, Bosma MM, Moody WJ. Spontaneous, synchronous electrical activity in neonatal mouse cortical neurones. J Physiol 2004; 560:377-90. [PMID: 15297578 PMCID: PMC1665264 DOI: 10.1113/jphysiol.2004.071621] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Spontaneous [Ca2+]i transients were measured in the mouse neocortex from embryonic day 16 (E16) to postnatal day 6 (P6). On the day of birth (P0), cortical neurones generated widespread, highly synchronous [Ca2+]i transients over large areas. On average, 52% of neurones participated in these transients, and in 20% of slices, an average of 80% participated. These transients were blocked by TTX and nifedipine, indicating that they resulted from Ca2+ influx during electrical activity, and occurred at a mean frequency of 0.91 min(-1). The occurrence of this activity was highly centred at P0: at E16 and P2 an average of only 15% and 24% of neurones, respectively, participated in synchronous transients, and they occurred at much lower frequencies at both E16 and P2 than at P0. The overall frequency of [Ca2+]i transients in individual cells did not change between E16 and P2, just the degree of their synchronicity. The onset of this spontaneous, synchronous activity correlated with a large increase in Na+ current density that occurred just before P0, and its cessation with a large decrease in resting resistance that occurred just after P2. This widespread, synchronous activity may serve a variety of functions in the neonatal nervous system.
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Affiliation(s)
- Rebekah Corlew
- Department of Biology, University of Washington, Seattle, WA 98115, USA
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Nakajo K, Okamura Y. Development of Transient Outward Currents Coupled With Ca2+-Induced Ca2+Release Mediates Oscillatory Membrane Potential in Ascidian Muscle Cells. J Neurophysiol 2004; 92:1056-66. [PMID: 15056691 DOI: 10.1152/jn.00043.2004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Isolated ascidian Halocynthia roretzi blastomeres of the muscle lineage exhibit muscle cell-like excitability on differentiation despite the arrest of cell cleavage early in development. This characteristic provides a unique opportunity to track changes in ion channel expression during muscle cell differentiation. Here, we show that the intrinsic membrane property of ascidian cleavage-arrested muscle-type cells becomes oscillatory by expressing transient outward currents ( Ito) activated by Ca2+-induced Ca2+release (CICR) in a maturation-dependent manner. In current-clamp mode, most day 4 (72 h after fertilization) cleavage-arrested muscle cells exhibited an oscillatory membrane potential of –20 mV at 15 Hz, whereas most day 3 (48 h after fertilization) cells exhibited a spiking pattern. In voltage-clamp mode, the day 4 cells exhibited prominent transient outward currents that were not present in day 3 cells. Itowas abolished by the application of 10 mM caffeine, implying that CICR was involved in Itoactivation. Itowas based on K+efflux and sensitive to tetraethylammonium and some Ca2+-activated K+channel inhibitors. We found a 60-pS single channel conductance that was activated by local Ca2+release in ascidian muscle cell. Voltage-clamp recording with an oscillatory waveform as a command pulse showed that CICR-activated K+currents were activated during the falling phase of the membrane potential oscillation. These results suggest that developmental expression of CICR-activated K+current plays a role in the maturation of larval locomotion by modifying the intrinsic membrane excitability of muscle cells.
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Affiliation(s)
- Koichi Nakajo
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, 153-8902 Tokyo, Japan.
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Gust J, Wright JJ, Pratt EB, Bosma MM. Development of synchronized activity of cranial motor neurons in the segmented embryonic mouse hindbrain. J Physiol 2003; 550:123-33. [PMID: 12730346 PMCID: PMC2343012 DOI: 10.1113/jphysiol.2002.038737] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2002] [Accepted: 04/04/2003] [Indexed: 11/08/2022] Open
Abstract
Spontaneous electrical activity synchronized among groups of related neurons is a widespread and important feature of central nervous system development. Among the many places from which spontaneous rhythmic activity has been recorded early in development are the cranial motor nerve roots that exit the hindbrain, the motor neuron pool that, at birth, will control the rhythmic motor patterns of swallow, feeding and the oral components of respiratory behaviour. Understanding the mechanism and significance of this hindbrain activity, however, has been hampered by the difficulty of identifying and recording from individual hindbrain motor neurons in living tissue. We have used retrograde labelling to identify living cranial branchiomeric motor neurons in the hindbrain, and [Ca2+]i imaging of such labelled cells to measure spontaneous activity simultaneously in groups of motor neuron somata. We find that branchiomeric motor neurons of the trigeminal and facial nerves generate spontaneous [Ca2+]i transients throughout the developmental period E9.5 to E11.5. During this two-day period the activity changes from low-frequency, long-duration events that are tetrodotoxin insensitive and poorly coordinated among cells, to high-frequency short-duration events that are tetrodotoxin sensitive and tightly coordinated throughout the motor neuron population. This early synchronization may be crucial for correct neuron-target development.
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Affiliation(s)
- J Gust
- Department of Zoology, Box 351800, University of Washington, Seattle, WA 98195-1800, USA
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Belmeguenai A, Leprince J, Tonon MC, Vaudry H, Louiset E. Neurotensin modulates the amplitude and frequency of voltage-activated Ca2+ currents in frog pituitary melanotrophs: implication of the inositol triphosphate/protein kinase C pathway. Eur J Neurosci 2002; 16:1907-16. [PMID: 12453054 DOI: 10.1046/j.1460-9568.2002.02296.x] [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: 11/20/2022]
Abstract
Many excitatory neurotransmitters and neuropeptides regulate the activity of neuronal and endocrine cells by modulating voltage-operated Ca2+ channels. Paradoxically, however, excitatory neuromediators that provoke mobilization of intracellular calcium from inositol trisphosphate (IP3)-sensitive stores usually inhibit voltage-gated Ca2+ currents. We have recently demonstrated that neurotensin (NT) stimulates the electrical and secretory activities of frog pituitary melanotrophs, and increases intracellular calcium concentration in these cells. In the present study, we have investigated the effects of NT on Ca2+ currents in cultured frog melanotrophs by using the perforated patch-clamp technique. Frog neurotensin (f NT) reduced the amplitude and facilitated the inactivation of both L- and N-type Ca2+ currents. Application of the membrane-permeant Ca2+ chelator BAPTA-AM, the sarcoendoplasmic reticulum Ca2+-ATPase inhibitor thapsigargin, or the IP3 receptor antagonist 2-APB suppressed the reduction of Ca2+ currents induced by f NT. Incubation of melanotrophs with the diacylglycerol analogue PMA, which causes desensitization of protein kinase C (PKC), or with the PKC inhibitors chelerythrine and calphostin C, reduced the inhibitory effect of f NT. The NT-induced action potential waveforms, applied as voltage-clamp commands, decreased the amplitude of Ca2+ currents, and enhanced Ca2+ influx by increasing the Ca2+ spike frequency. Altogether, these data indicate that the inhibitory effect of f NT on Ca2+ currents results from activation of the IP3/PKC pathway. The observation that NT controls Ca2+ signalling through both amplitude and frequency modulations of Ca2+ currents suggests that NT might induce spacial and temporal changes of intracellular Ca2+ concentration leading to stimulation of exocytosis.
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Affiliation(s)
- Amor Belmeguenai
- European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U-413, UA CNRS, University of Rouen, 76821 Mont-Saint-Aignan, France
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Meinertzhagen IA, Okamura Y. The larval ascidian nervous system: the chordate brain from its small beginnings. Trends Neurosci 2001; 24:401-10. [PMID: 11410271 DOI: 10.1016/s0166-2236(00)01851-8] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The body plan of the tadpole larva of ascidians, or sea-squirts, is widely presumed to be close to that of the hypothetical ancestor of all chordate animal groups, including vertebrates. This is nowhere more obvious than in the organization and development of the dorsal tubular nervous system. Several recent developments advocate this model neural system for studies on neurobiology and neurogenesis. These include advances in our understanding of development in ascidian embryos and of differentiation among the cellular progeny of its neural plate; the application of transgenic and mutant approaches to studies on ascidian larval neurones; and the prospect of advances in genomic analyses. In addition to providing ways to study a working chordate brain in miniature, all these offer insights into the ancestral condition of the developing vertebrate brain.
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Affiliation(s)
- I A Meinertzhagen
- Neuroscience Institute, Life Sciences Centre, Dalhousie University, Halifax, NS, B3H 4J1, Canada
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