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Scherer JS, Riedesel OE, Arkhypchuk I, Meiser S, Kretzberg J. Initial Variability and Time-Dependent Changes of Neuronal Response Features Are Cell-Type-Specific. Front Cell Neurosci 2022; 16:858221. [PMID: 35573827 PMCID: PMC9092978 DOI: 10.3389/fncel.2022.858221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 03/16/2022] [Indexed: 11/13/2022] Open
Abstract
Different cell types are commonly defined by their distinct response features. But several studies proved substantial variability between cells of the same type, suggesting rather the appraisal of response feature distributions than a limitation to "typical" responses. Moreover, there is growing evidence that time-dependent changes of response features contribute to robust and functional network output in many neuronal systems. The individually characterized Touch (T), Pressure (P), and Retzius (Rz) cells in the medicinal leech allow for a rigid analysis of response features, elucidating differences between and variability within cell types, as well as their changes over time. The initial responses of T and P cells to somatic current injection cover a wide range of spike counts, and their first spike is generated with a high temporal precision after a short latency. In contrast, all Rz cells elicit very similar low spike counts with variable, long latencies. During prolonged electrical stimulation the resting membrane potential of all three cell types hyperpolarizes. At the same time, Rz cells reduce their spiking activity as expected for a departure from the spike threshold. In contrast, both mechanoreceptor types increase their spike counts during repeated stimulation, consistent with previous findings in T cells. A control experiment reveals that neither a massive current stimulation nor the hyperpolarization of the membrane potential is necessary for the mechanoreceptors' increase in excitability over time. These findings challenge the previously proposed involvement of slow K+-channels in the time-dependent activity changes. We also find no indication for a run-down of HCN channels over time, and a rigid statistical analysis contradicts several potential experimental confounders as the basis of the observed variability. We conclude that the time-dependent change in excitability of T and P cells could indicate a cell-type-specific shift between different spiking regimes, which also could explain the high variability in the initial responses. The underlying mechanism needs to be further investigated in more naturalistic experimental situations to disentangle the effects of varying membrane properties versus network interactions. They will show if variability in individual response features serves as flexible adaptation to behavioral contexts rather than just "randomness".
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Affiliation(s)
- Jens-Steffen Scherer
- Computational Neuroscience, Department of Neuroscience, Faculty VI, University of Oldenburg, Oldenburg, Germany
| | - Oda E. Riedesel
- Computational Neuroscience, Department of Neuroscience, Faculty VI, University of Oldenburg, Oldenburg, Germany
| | - Ihor Arkhypchuk
- Computational Neuroscience, Department of Neuroscience, Faculty VI, University of Oldenburg, Oldenburg, Germany
| | - Sonja Meiser
- Computational Neuroscience, Department of Neuroscience, Faculty VI, University of Oldenburg, Oldenburg, Germany
| | - Jutta Kretzberg
- Computational Neuroscience, Department of Neuroscience, Faculty VI, University of Oldenburg, Oldenburg, Germany
- Cluster of Excellence Hearing4all, Department of Neuroscience, Faculty VI, University of Oldenburg, Oldenburg, Germany
- Research Center Neurosensory Science, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany
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Heath-Heckman E, Yoo S, Winchell C, Pellegrino M, Angstadt J, Lammardo VB, Bautista D, De-Miguel FF, Weisblat D. Transcriptional profiling of identified neurons in leech. BMC Genomics 2021; 22:215. [PMID: 33765928 PMCID: PMC7992859 DOI: 10.1186/s12864-021-07526-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 03/11/2021] [Indexed: 12/13/2022] Open
Abstract
Background While leeches in the genus Hirudo have long been models for neurobiology, the molecular underpinnings of nervous system structure and function in this group remain largely unknown. To begin to bridge this gap, we performed RNASeq on pools of identified neurons of the central nervous system (CNS): sensory T (touch), P (pressure) and N (nociception) neurons; neurosecretory Retzius cells; and ganglia from which these four cell types had been removed. Results Bioinformatic analyses identified 3565 putative genes whose expression differed significantly among the samples. These genes clustered into 9 groups which could be associated with one or more of the identified cell types. We verified predicted expression patterns through in situ hybridization on whole CNS ganglia, and found that orthologous genes were for the most part similarly expressed in a divergent leech genus, suggesting evolutionarily conserved roles for these genes. Transcriptional profiling allowed us to identify candidate phenotype-defining genes from expanded gene families. Thus, we identified one of eight hyperpolarization-activated cyclic-nucleotide gated (HCN) channels as a candidate for mediating the prominent sag current in P neurons, and found that one of five inositol triphosphate receptors (IP3Rs), representing a sub-family of IP3Rs absent from vertebrate genomes, is expressed with high specificity in T cells. We also identified one of two piezo genes, two of ~ 65 deg/enac genes, and one of at least 16 transient receptor potential (trp) genes as prime candidates for involvement in sensory transduction in the three distinct classes of leech mechanosensory neurons. Conclusions Our study defines distinct transcriptional profiles for four different neuronal types within the leech CNS, in addition to providing a second ganglionic transcriptome for the species. From these data we identified five gene families that may facilitate the sensory capabilities of these neurons, thus laying the basis for future work leveraging the strengths of the leech system to investigate the molecular processes underlying and linking mechanosensation, cell type specification, and behavior. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07526-0.
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Affiliation(s)
- Elizabeth Heath-Heckman
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA. .,Current address: Department of Integrative Biology, Michigan State University, East Lansing, MI, USA.
| | - Shinja Yoo
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Christopher Winchell
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Maurizio Pellegrino
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA.,Current address: Invitae Corporation, San Francisco, CA, USA
| | - James Angstadt
- Department of Biology, Siena College, Loudonville, New York, NY, USA
| | | | - Diana Bautista
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Francisco F De-Miguel
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - David Weisblat
- Department of Molecular & Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
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Angstadt JD, Rebel MI, Connolly MK. Effects of calcium-activated potassium channel modulators on afterhyperpolarizing potentials in identified motor and mechanosensory neurons of the medicinal leech. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2021; 207:69-85. [PMID: 33483833 DOI: 10.1007/s00359-021-01462-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/30/2020] [Accepted: 01/02/2021] [Indexed: 11/26/2022]
Abstract
Calcium-activated potassium (KCa) channels contribute to multiple neuronal properties including spike frequency and afterhyperpolarizing potentials (AHPs). KCa channels are classified as KCa1.1, KCa2, or KCa3.1 based on single-channel conductance and pharmacology. Ca2+-dependent AHPs in vertebrates are categorized as fast, medium, or slow. Fast and medium AHPs are generated by KCa1.1 and KCa2 channels, respectively. The KCa subtype responsible for slow AHPs is unclear. Prolonged, Ca2+-dependent AHPs have been described in several leech neurons. Unfortunately, apamin and other KCa blockers often prove ineffective in the leech. An alternative approach is to utilize KCa modulators, which alter channel sensitivity to Ca2+. Vertebrate KCa2 channels are targeted selectively by the positive modulator CyPPA and the negative modulator NS8593. Here we show that AHPs in identified motor and mechanosensory leech neurons are enhanced by CyPPA and suppressed by NS8593. Our results indicate that KCa2 channels underlie prolonged AHPs in these neurons and suggest that KCa2 modulators may serve as effective tools to explore the role of KCa channels in leech physiology.
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Affiliation(s)
| | - Matthew I Rebel
- Siena College, Loudonville, NY, USA
- College of Medicine, SUNY Upstate Medical University, Syracuse, NY, USA
| | - Megan K Connolly
- Siena College, Loudonville, NY, USA
- Physician Assistant Studies Department, Marist College, Poughkeepsie, NY, USA
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Meiser S, Ashida G, Kretzberg J. Non-synaptic Plasticity in Leech Touch Cells. Front Physiol 2019; 10:1444. [PMID: 31827443 PMCID: PMC6890822 DOI: 10.3389/fphys.2019.01444] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 11/08/2019] [Indexed: 01/06/2023] Open
Abstract
The role of Na+/K+-pumps in activity-dependent synaptic plasticity has been described in both vertebrates and invertebrates. Here, we provide evidence that the Na+/K+-pump is also involved in activity-dependent non-synaptic cellular plasticity in leech sensory neurons. We show that the resting membrane potential (RMP) of T cells hyperpolarizes in response to repeated somatic current injection, while at the same time their spike count (SC) and the input resistance (IR) increase. Our Hodgkin–Huxley-type neuron model, adjusted to physiological T cell properties, suggests that repetitive action potential discharges lead to increased Na+/K+-pump activity, which then hyperpolarizes the RMP. In consequence, a slow, non-inactivating current decreases, which is presumably mediated by voltage-dependent, low-threshold potassium channels. Closing of these putative M-type channels due to hyperpolarization of the resting potential increases the IR of the cell, leading to a larger number of spikes. By this mechanism, the response behavior switches from rapidly to slowly adapting spiking. These changes in spiking behavior also effect other T cells on the same side of the ganglion, which are connected via a combination of electrical and chemical synapses. An increased SC in the presynaptic T cell results in larger postsynaptic responses (PRs) in the other T cells. However, when the number of elicited presynaptic spikes is kept constant, the PR does not change. These results suggest that T cells change their responses in an activity-dependent manner through non-synaptic rather than synaptic plasticity. These changes might act as a gain-control mechanism. Depending on the previous activity, this gain could scale the relative impacts of synaptic inputs from other mechanoreceptors, versus the spike responses to tactile skin stimulation. This multi-tasking ability, and its flexible adaptation to previous activity, might make the T cell a key player in a preparatory network, enabling the leech to perform fast behavioral reactions to skin stimulation.
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Affiliation(s)
- Sonja Meiser
- Computational Neuroscience, Department of Neuroscience, Faculty VI, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Go Ashida
- Computational Neuroscience, Department of Neuroscience, Faculty VI, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany.,Cluster of Excellence Hearing4all, Department of Neuroscience, Faculty VI, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Jutta Kretzberg
- Computational Neuroscience, Department of Neuroscience, Faculty VI, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany.,Cluster of Excellence Hearing4all, Department of Neuroscience, Faculty VI, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
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Picton LD, Sillar KT, Zhang HY. Control of Xenopus Tadpole Locomotion via Selective Expression of Ih in Excitatory Interneurons. Curr Biol 2018; 28:3911-3923.e2. [PMID: 30503615 PMCID: PMC6303192 DOI: 10.1016/j.cub.2018.10.048] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/06/2018] [Accepted: 10/22/2018] [Indexed: 11/16/2022]
Abstract
Locomotion relies on the coordinated activity of rhythmic neurons in the hindbrain and spinal cord and depends critically on the intrinsic properties of excitatory interneurons. Therefore, understanding how ion channels sculpt the properties of these interneurons, and the consequences for circuit function and behavior, is an important task. The hyperpolarization-activated cation current, Ih, is known to play important roles in shaping neuronal properties and for rhythm generation in many neuronal networks. We show in stage 42 Xenopus laevis frog tadpoles that Ih is strongly expressed only in excitatory descending interneurons (dINs), an important ipsilaterally projecting population that drives swimming activity. The voltage-dependent HCN channel blocker ZD7288 completely abolished a prominent depolarizing sag potential in response to hyperpolarization, the hallmark of Ih, and hyperpolarized dINs. ZD7288 also affected dIN post-inhibitory rebound firing, upon which locomotor rhythm generation relies, and disrupted locomotor output. Block of Ih also unmasked an activity-dependent ultraslow afterhyperpolarization (usAHP) in dINs following swimming, mediated by a dynamic Na/K pump current. This usAHP, unmasked in dINs by ZD7288, resulted in suprathreshold stimuli failing to evoke swimming at short inter-swim intervals, indicating an important role for Ih in maintaining swim generation capacity and in setting the post-swim refractory period of the network. Collectively, our data suggest that the selective expression of Ih in dINs determines specific dIN properties that are important for rhythm generation and counteracts an activity-dependent usAHP to ensure that dINs can maintain coordinated swimming over a wide range of inter-swim intervals. Ih is strongly expressed in Xenopus locomotor-rhythm-generating dIN interneurons Ih is active at rest in dINs, contributing to their distinct electrical properties dINs normally lack a Na pump-dependent ultra-slow afterhyperpolarization (usAHP) Ih counterbalances dIN usAHPs to preserve tadpole rhythm generating capacity
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Affiliation(s)
- Laurence D Picton
- School of Psychology and Neuroscience, University of St Andrews, St Andrews KY16 9JP, UK
| | - Keith T Sillar
- School of Psychology and Neuroscience, University of St Andrews, St Andrews KY16 9JP, UK
| | - Hong-Yan Zhang
- Centre for Discovery Brain Sciences, Edinburgh Medical School, University of Edinburgh, Edinburgh EH16 4SB, UK.
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Fischer L, Scherbarth F, Chagnaud B, Felmy F. Intrinsic frequency response patterns in mechano-sensory neurons of the leech. Biol Open 2017; 6:993-999. [PMID: 28546342 PMCID: PMC5550909 DOI: 10.1242/bio.023960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Animals employ mechano-sensory systems to detect and explore their environment. Mechano-sensation encompasses stimuli such as constant pressure, surface movement or vibrations at various intensities that need to be segregated in the central nervous system. Besides different receptor structures, sensory filtering via intrinsic response properties could provide a convenient way to solve this problem. In leech, three major mechano-sensory cell types can be distinguished, according to their stimulus sensitivity, as nociceptive, pressure and touch cells. Using intracellular recordings, we show that the different mechano-sensory neuron classes in Hirudo medicinalis differentially respond supra-threshold to distinct frequencies of sinusoidal current injections between 0.2 and 20 Hz. Nociceptive cells responded with a low-pass filter characteristic, pressure cells as high-pass filters and touch cells as an intermediate band-pass filter. Each class of mechano-sensory neurons is thus intrinsically tuned to a specific frequency range of voltage oscillation that could help segregate mechano-sensory information centrally. Summary: Mechano-sensitive neurons of leech are intrinsically tuned to generate somatic input-output functions with distinct filter properties.
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Affiliation(s)
- Linda Fischer
- Institute of Zoology, University of Veterinary Medicine Hannover, Buenteweg 17, Hannover 30559, Germany
| | - Frank Scherbarth
- Institute of Zoology, University of Veterinary Medicine Hannover, Buenteweg 17, Hannover 30559, Germany
| | - Boris Chagnaud
- Department Biology II, Ludwig-Maximilians-University Munich, Großhadener Straße 2, Planegg/Martinsried 82152, Germany
| | - Felix Felmy
- Institute of Zoology, University of Veterinary Medicine Hannover, Buenteweg 17, Hannover 30559, Germany
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Neyer C, Herr D, Kohmann D, Budde T, Pape HC, Coulon P. mGluR-mediated calcium signalling in the thalamic reticular nucleus. Cell Calcium 2016; 59:312-23. [PMID: 27041217 DOI: 10.1016/j.ceca.2016.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 03/22/2016] [Accepted: 03/23/2016] [Indexed: 10/22/2022]
Abstract
The thalamic reticular nucleus (TRN) plays a major role in modulating the transfer of information from the thalamus to the cortex. GABAergic inhibition via the TRN is differentially regulated by metabotropic glutamate receptors (mGluRs) and the effect of mGluRs on the membrane potential, on ion channels, and on the plasticity of electrical coupling of TRN neurons has been studied previously. Although mGluRs are generally known to trigger Ca(2+) transients, mGluR-mediated Ca(2+)-transients in TRN neurons have not yet been investigated. In this study, we show that mGluRs can trigger Ca(2+)-transients in TRN neurons, that these transients depend on intracellular Ca(2+)-stores, and are mediated by IP3 receptors. Ca(2+) transients caused by the group I mGluR agonist DHPG elicit a current that is sensitive to flufenamic acid and has a reversal potential around -40mV. Our results add mGluR-mediated Ca(2+)-signalling in the TRN to the state-dependent modulators of the thalamocortical system.
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Affiliation(s)
- Christina Neyer
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Münster, Germany
| | - David Herr
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Münster, Germany
| | - Denise Kohmann
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Münster, Germany
| | - Thomas Budde
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Münster, Germany
| | - Hans-Christian Pape
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Münster, Germany
| | - Philippe Coulon
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Münster, Germany; Center For Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA.
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Hooper SL, Thuma JB, Guschlbauer C, Schmidt J, Büschges A. Cell dialysis by sharp electrodes can cause nonphysiological changes in neuron properties. J Neurophysiol 2015; 114:1255-71. [PMID: 26063785 DOI: 10.1152/jn.01010.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 06/04/2015] [Indexed: 11/22/2022] Open
Abstract
We recorded from lobster and leech neurons with two sharp electrodes filled with solutions often used with these preparations (lobster: 0.6 M K2SO4 or 2.5 M KAc; leech: 4 M KAc), with solutions approximately matching neuron cytoplasm ion concentrations, and with 6.5 M KAc (lobster, leech) and 0.6 M KAc (lobster). We measured membrane potential, input resistance, and transient and sustained depolarization-activated outward current amplitudes in leech and these neuron properties and hyperpolarization-activated current time constant in lobster, every 10 min for 60 min after electrode penetration. Neuron properties varied with electrode fill. For fills with molarities ≥2.5 M, neuron properties also varied strongly with time after electrode penetration. Depending on the property being examined, these variations could be large. In leech, cell size also increased with noncytoplasmic fills. The changes in neuron properties could be due to the ions being injected from the electrodes during current injection. We tested this possibility in lobster with the 2.5 M KAc electrode fill by making measurements only 10 and 60 min after penetration. Neuron properties still changed, although the changes were less extreme. Making measurements every 2 min showed that the time-dependent variations in neuron properties occurred in concert with each other. Neuron property changes with high molarity electrode-fill solutions were great enough to decrease neuron firing strongly. An experiment with (14)C-glucose electrode fill confirmed earlier work showing substantial leak from sharp electrodes. Sharp electrode work should thus be performed with cytoplasm-matched electrode fills.
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Affiliation(s)
- Scott L Hooper
- Department of Biological Sciences, Ohio University, Athens, Ohio; and Zoologisches Institut, Universität zu Köln, Köln, Germany
| | - Jeffrey B Thuma
- Department of Biological Sciences, Ohio University, Athens, Ohio; and
| | - Christoph Guschlbauer
- Department of Biological Sciences, Ohio University, Athens, Ohio; and Zoologisches Institut, Universität zu Köln, Köln, Germany
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