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Zhantiev R, Korsunovskaya O. Bimodality of auditory receptors in bush-crickets. Сontinued discussion. It's time to experiment. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2023; 339:961-966. [PMID: 37559464 DOI: 10.1002/jez.2745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 07/28/2023] [Accepted: 07/29/2023] [Indexed: 08/11/2023]
Abstract
Continuation of the discussion on the sensitivity of the chordotonal sensilla of the tympanal organ of bush-crickets to vibratory stimuli. We have previously shown that individual receptors registered directly in the tympanal organ perceive vibrations along with sound stimuli. In addition, scolopidia of the crista acustica possess mixed sensitivity, too, as well as receptors of the intermediate organ. The authors of the comment offered their opinion concerning our applied methods as well as our obtained results. In particular, they noted the dissimilarity of our data from the previously obtained data (the 1970s-1990s), mainly in the laboratory of Prof. K. Kalmring, who assumed that only low-frequency receptors, in particular receptors of the intermediate organ, possess mixed sensitivity. At the same time, receptor activity was recorded in the tympanal nerve without morphological identification of receptors (with the exception of one stained neuron in the prothoracic ganglion). We carried out a series of experiments using the method of K. Kalmring and found that it is possible to register several receptors in the tympanal nerve with different reactions during one experiment: to sound only, also both to vibration stimuli and sound. In the latter case, we dealt with low-threshold receptors, which responded to ultrasound, and this with high probability belonged to the crista acustica. Similar data were previously obtained on the bush-cricket Decticus verrucivorus. In this publication, we explain the methodological features of our work and suggest that the loss of sensitivity to vibrations at the level of the tympanal nerve by some auditory receptors may be due to the ephaptic and/or chemical interaction of the tympanal organ receptors with vibroreceptors of the subgenual or other organs. To verify this hypothesis, it is necessary to conduct additional studies, such as physiological, morphological, and immunohistochemical, along the entire vibroacoustic afferent tract, that is, from the peripheral part to the first switches to the corresponding interneurons.
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Affiliation(s)
- Rustem Zhantiev
- Department of Entomology, Lomonosov Moscow State University, Moscow, Russia
| | - Olga Korsunovskaya
- Department of Entomology, Lomonosov Moscow State University, Moscow, Russia
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2
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Gilloteaux J, De Swert K, Suain V, Brion JP, Nicaise C. Loss of Ephaptic Contacts in the Murine Thalamus during Osmotic Demyelination Syndrome. Ultrastruct Pathol 2023; 47:398-423. [PMID: 37477534 DOI: 10.1080/01913123.2023.2232452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/10/2023] [Accepted: 06/29/2023] [Indexed: 07/22/2023]
Abstract
BACKGROUND AND AIM A murine model mimicking osmotic demyelination syndrome (ODS) revealed with histology in the relay posterolateral (VPL) and ventral posteromedial (VPM) thalamic nuclei adjoined nerve cell bodies in chronic hyponatremia, amongst the damaged 12 h and 48 h after reinstatement of osmolality. This report aims to verify and complement with ultrastructure other neurophysiology, immunohistochemistry, and molecular biochemistry data to assess the connexin-36 protein, as part of those hinted close contacts.This ODS investigation included four groups of mice: Sham (NN; n = 13), hyponatremic (HN; n = 11), those sacrificed 12 h after a fast restoration of normal natremia (ODS12h; n = 6) and mice sacrificed 48 h afterward, or ODS48 h (n = 9). Out of these, thalamic zones samples included NN (n = 2), HN (n = 2), ODS12h (n = 3) and ODS48h (n = 3). RESULTS Ultrastructure illustrated junctions between nerve cell bodies that were immunolabeled with connexin36 (Cx36) with light microscopy and Western blots. These cell's junctions were reminiscent of low resistance junctions characterized in other regions of the CNS with electrophysiology. Contiguous neurons showed neurolemma contacts in intact and damaged tissues according to their location in the ODS zones, at 12 h and 48 h post correction along with other demyelinating alterations. Neurons and ephaptic contact measurements indicated the highest alterations, including nerve cell necrosis in the ODS epicenter and damages decreased toward the outskirts of the demyelinated zone. CONCLUSION Ephapses contained C × 36between intact or ODS injured neurons in the thalamus appeared to be resilient beyond the core degraded tissue injuries. These could maintain intercellular ionic and metabolite exchanges between these lesser injured regions and, thus, would partake to some brain plasticity repairs.
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Affiliation(s)
- Jacques Gilloteaux
- Department of Medicine, URPHyM, NARILIS, Université de Namur, Namur, Belgium
- Department of Anatomical Sciences, St George's University School of Medicine, Newcastle Upon Tyne, UK
| | - Kathleen De Swert
- Department of Medicine, URPHyM, NARILIS, Université de Namur, Namur, Belgium
| | - Valérie Suain
- Laboratory of Histology, Neuroanatomy and Neuropathology, Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium
| | - Jean-Pierre Brion
- Laboratory of Histology, Neuroanatomy and Neuropathology, Faculty of Medicine, Université Libre de Bruxelles, Brussels, Belgium
| | - Charles Nicaise
- Department of Medicine, URPHyM, NARILIS, Université de Namur, Namur, Belgium
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Wheelwright M, Whittle CR, Riabinina O. Olfactory systems across mosquito species. Cell Tissue Res 2021; 383:75-90. [PMID: 33475852 PMCID: PMC7873006 DOI: 10.1007/s00441-020-03407-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/15/2020] [Indexed: 01/06/2023]
Abstract
There are 3559 species of mosquitoes in the world (Harbach 2018) but, so far, only a handful of them have been a focus of olfactory neuroscience and neurobiology research. Here we discuss mosquito olfactory anatomy and function and connect these to mosquito ecology. We highlight the least well-known and thus most interesting aspects of mosquito olfactory systems and discuss promising future directions. We hope this review will encourage the insect neuroscience community to work more broadly across mosquito species instead of focusing narrowly on the main disease vectors.
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Affiliation(s)
- Matthew Wheelwright
- Department of Biosciences, Durham University, Stockton Road, Durham, DH1 3LE, UK
| | - Catherine R Whittle
- Department of Biosciences, Durham University, Stockton Road, Durham, DH1 3LE, UK
| | - Olena Riabinina
- Department of Biosciences, Durham University, Stockton Road, Durham, DH1 3LE, UK.
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4
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Xu P, Choo YM, Chen Z, Zeng F, Tan K, Chen TY, Cornel AJ, Liu N, Leal WS. Odorant Inhibition in Mosquito Olfaction. iScience 2019; 19:25-38. [PMID: 31349189 PMCID: PMC6660600 DOI: 10.1016/j.isci.2019.07.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 04/22/2019] [Accepted: 07/03/2019] [Indexed: 01/03/2023] Open
Abstract
How chemical signals are integrated at the peripheral sensory system of insects is still an enigma. Here we show that when coexpressed with Orco in Xenopus oocytes, an odorant receptor from the southern house mosquito, CquiOR32, generated inward (regular) currents when challenged with cyclohexanone and methyl salicylate, whereas eucalyptol and fenchone elicited inhibitory (upward) currents. Responses of CquiOR32-CquiOrco-expressing oocytes to odorants were reduced in a dose-dependent fashion by coapplication of inhibitors. This intrareceptor inhibition was also manifested in vivo in fruit flies expressing the mosquito receptor CquiOR32, as well in neurons on the antennae of the southern house mosquito. Likewise, an orthologue from the yellow fever mosquito, AaegOR71, showed intrareceptor inhibition in the Xenopus oocyte recording system and corresponding inhibition in antennal neurons. Inhibition was also manifested in mosquito behavior. Blood-seeking females were repelled by methyl salicylate, but repellence was significantly reduced when methyl salicylate was coapplied with eucalyptol. We found dual inhibitory/excitatory odorant receptors (ORs) in mosquitoes Inhibitory and endogenous ORs coexpressed in flies showed lateral inhibition The bipolar nature of these inhibitory ORs was displayed in electrophysiology The duality excitation/inhibition was also manifested in mosquito behavior
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Affiliation(s)
- Pingxi Xu
- Department of Molecular and Cellular Biology, University of California-Davis, Davis, CA 95616, USA
| | - Young-Moo Choo
- Department of Molecular and Cellular Biology, University of California-Davis, Davis, CA 95616, USA
| | - Zhou Chen
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36489, USA
| | - Fangfang Zeng
- Department of Molecular and Cellular Biology, University of California-Davis, Davis, CA 95616, USA
| | - Kaiming Tan
- Department of Molecular and Cellular Biology, University of California-Davis, Davis, CA 95616, USA
| | - Tsung-Yu Chen
- Center for Neuroscience, Department of Neurology, University of California-Davis, Davis, CA 95616, USA
| | - Anthony J Cornel
- Department of Entomology and Nematology, University of California-Davis, Davis, CA 95616, USA
| | - Nannan Liu
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36489, USA
| | - Walter S Leal
- Department of Molecular and Cellular Biology, University of California-Davis, Davis, CA 95616, USA.
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5
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Zhang Y, Tsang TK, Bushong EA, Chu LA, Chiang AS, Ellisman MH, Reingruber J, Su CY. Asymmetric ephaptic inhibition between compartmentalized olfactory receptor neurons. Nat Commun 2019; 10:1560. [PMID: 30952860 PMCID: PMC6451019 DOI: 10.1038/s41467-019-09346-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 03/04/2019] [Indexed: 11/09/2022] Open
Abstract
In the Drosophila antenna, different subtypes of olfactory receptor neurons (ORNs) housed in the same sensory hair (sensillum) can inhibit each other non-synaptically. However, the mechanisms underlying this underexplored form of lateral inhibition remain unclear. Here we use recordings from pairs of sensilla impaled by the same tungsten electrode to demonstrate that direct electrical ("ephaptic") interactions mediate lateral inhibition between ORNs. Intriguingly, within individual sensilla, we find that ephaptic lateral inhibition is asymmetric such that one ORN exerts greater influence onto its neighbor. Serial block-face scanning electron microscopy of genetically identified ORNs and circuit modeling indicate that asymmetric lateral inhibition reflects a surprisingly simple mechanism: the physically larger ORN in a pair corresponds to the dominant neuron in ephaptic interactions. Thus, morphometric differences between compartmentalized ORNs account for highly specialized inhibitory interactions that govern information processing at the earliest stages of olfactory coding.
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Affiliation(s)
- Ye Zhang
- Neurobiology Section, Division of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Tin Ki Tsang
- Neurobiology Section, Division of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Eric A Bushong
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Li-An Chu
- Brain Research Center, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan
| | - Ann-Shyn Chiang
- Brain Research Center, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, 30013, Taiwan
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA
| | - Jürgen Reingruber
- Institut of Biology, École Normale Supérieure (IBENS), 46 rue d'Ulm, 75005, Paris, France.,INSERM U1024, 75005, Paris, France
| | - Chih-Ying Su
- Neurobiology Section, Division of Biological Sciences, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
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Chan HK, Hersperger F, Marachlian E, Smith BH, Locatelli F, Szyszka P, Nowotny T. Odorant mixtures elicit less variable and faster responses than pure odorants. PLoS Comput Biol 2018; 14:e1006536. [PMID: 30532147 PMCID: PMC6287832 DOI: 10.1371/journal.pcbi.1006536] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 09/29/2018] [Indexed: 11/18/2022] Open
Abstract
In natural environments, odors are typically mixtures of several different chemical compounds. However, the implications of mixtures for odor processing have not been fully investigated. We have extended a standard olfactory receptor model to mixtures and found through its mathematical analysis that odorant-evoked activity patterns are more stable across concentrations and first-spike latencies of receptor neurons are shorter for mixtures than for pure odorants. Shorter first-spike latencies arise from the nonlinear dependence of binding rate on odorant concentration, commonly described by the Hill coefficient, while the more stable activity patterns result from the competition between different ligands for receptor sites. These results are consistent with observations from numerical simulations and physiological recordings in the olfactory system of insects. Our results suggest that mixtures allow faster and more reliable olfactory coding, which could be one of the reasons why animals often use mixtures in chemical signaling.
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Affiliation(s)
- Ho Ka Chan
- Sussex Neuroscience, School of Engineering and Informatics, University of Sussex, Falmer, Brighton, United Kingdom
| | - Fabian Hersperger
- Department of Neuroscience, University of Konstanz, Konstanz, Germany
| | - Emiliano Marachlian
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET) and Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Brian H. Smith
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Fernando Locatelli
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE-UBA-CONICET) and Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Buenos Aires, Argentina
| | - Paul Szyszka
- Department of Neuroscience, University of Konstanz, Konstanz, Germany
| | - Thomas Nowotny
- Sussex Neuroscience, School of Engineering and Informatics, University of Sussex, Falmer, Brighton, United Kingdom
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Faber DS, Pereda AE. Two Forms of Electrical Transmission Between Neurons. Front Mol Neurosci 2018; 11:427. [PMID: 30534051 PMCID: PMC6276723 DOI: 10.3389/fnmol.2018.00427] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 11/05/2018] [Indexed: 12/30/2022] Open
Abstract
Electrical signaling is a cardinal feature of the nervous system and endows it with the capability of quickly reacting to changes in the environment. Although synaptic communication between nerve cells is perceived to be mainly chemically mediated, electrical synaptic interactions also occur. Two different strategies are responsible for electrical communication between neurons. One is the consequence of low resistance intercellular pathways, called "gap junctions", for the spread of electrical currents between the interior of two cells. The second occurs in the absence of cell-to-cell contacts and is a consequence of the extracellular electrical fields generated by the electrical activity of neurons. Here, we place present notions about electrical transmission in a historical perspective and contrast the contributions of the two different forms of electrical communication to brain function.
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Affiliation(s)
- Donald S. Faber
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
- Marine Biological Laboratory, Woods Hole, MA, United States
| | - Alberto E. Pereda
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
- Marine Biological Laboratory, Woods Hole, MA, United States
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8
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Takeichi Y, Uebi T, Miyazaki N, Murata K, Yasuyama K, Inoue K, Suzaki T, Kubo H, Kajimura N, Takano J, Omori T, Yoshimura R, Endo Y, Hojo MK, Takaya E, Kurihara S, Tatsuta K, Ozaki K, Ozaki M. Putative Neural Network Within an Olfactory Sensory Unit for Nestmate and Non-nestmate Discrimination in the Japanese Carpenter Ant: The Ultra-structures and Mathematical Simulation. Front Cell Neurosci 2018; 12:310. [PMID: 30283303 PMCID: PMC6157317 DOI: 10.3389/fncel.2018.00310] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/27/2018] [Indexed: 11/13/2022] Open
Abstract
Ants are known to use a colony-specific blend of cuticular hydrocarbons (CHCs) as a pheromone to discriminate between nestmates and non-nestmates and the CHCs were sensed in the basiconic type of antennal sensilla (S. basiconica). To investigate the functional design of this type of antennal sensilla, we observed the ultra-structures at 2D and 3D in the Japanese carpenter ant, Camponotus japonicus, using a serial block-face scanning electron microscope (SBF-SEM), and conventional and high-voltage transmission electron microscopes. Based on the serial images of 352 cross sections of SBF-SEM, we reconstructed a 3D model of the sensillum revealing that each S. basiconica houses > 100 unbranched dendritic processes, which extend from the same number of olfactory receptor neurons (ORNs). The dendritic processes had characteristic beaded-structures and formed a twisted bundle within the sensillum. At the "beads," the cell membranes of the processes were closely adjacent in the interdigitated profiles, suggesting functional interactions via gap junctions (GJs). Immunohistochemistry with anti-innexin (invertebrate GJ protein) antisera revealed positive labeling in the antennae of C. japonicus. Innexin 3, one of the five antennal innexin subtypes, was detected as a dotted signal within the S. basiconica as a sensory organ for nestmate recognition. These morphological results suggest that ORNs form an electrical network via GJs between dendritic processes. We were unable to functionally certify the electric connections in an olfactory sensory unit comprising such multiple ORNs; however, with the aid of simulation of a mathematical model, we examined the putative function of this novel chemosensory information network, which possibly contributes to the distinct discrimination of colony-specific blends of CHCs or other odor detection.
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Affiliation(s)
- Yusuke Takeichi
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
| | - Tatsuya Uebi
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
| | | | | | - Kouji Yasuyama
- Division of Biology, Department of Natural Sciences, Kawasaki Medical School, Kurashiki, Japan
| | - Kanako Inoue
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki, Japan
| | - Toshinobu Suzaki
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
| | - Hideo Kubo
- Department of Mathematics, Faculty of Sciences, Hokkaido University, Sapporo, Japan
| | - Naoko Kajimura
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Jo Takano
- Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Toshiaki Omori
- Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Kobe, Japan
| | - Ryoichi Yoshimura
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan
| | - Yasuhisa Endo
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan
| | - Masaru K Hojo
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
| | - Eichi Takaya
- Graduate School of Information Systems, The University of Electro-Communications, Chofu, Japan
| | - Satoshi Kurihara
- Graduate School of Information Systems, The University of Electro-Communications, Chofu, Japan
| | - Kenta Tatsuta
- Department of Biological Science, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan
| | - Koichi Ozaki
- Department of Biological Science, Faculty of Life and Environmental Science, Shimane University, Matsue, Japan
| | - Mamiko Ozaki
- Department of Biology, Graduate School of Science, Kobe University, Kobe, Japan
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Signaling Mode of the Broad-Spectrum Conserved CO 2 Receptor Is One of the Important Determinants of Odor Valence in Drosophila. Neuron 2018; 97:1153-1167.e4. [PMID: 29429938 DOI: 10.1016/j.neuron.2018.01.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 11/17/2017] [Accepted: 01/11/2018] [Indexed: 12/24/2022]
Abstract
Odor detection involves hundreds of olfactory receptors from diverse families, making modeling of hedonic valence of an odorant difficult, even in Drosophila melanogaster where most receptors have been deorphanised. We demonstrate that a broadly tuned heteromeric receptor that detects CO2 (Gr21a, Gr63a) and other odorants is a key determinant of valence along with a few members of the Odorant receptor family in a T-maze, but not in a trap assay. Gr21a and Gr63a have atypically high amino acid conservation in Dipteran insects, and they use both inhibition and activation to convey positive or negative valence for numerous odorants. Inhibitors elicit a robust Gr63a-dependent attraction, while activators, strong aversion. The attractiveness of inhibitory odorants increases with increasing background CO2 levels, providing a mechanism for behavior modulation in odor blends. In mosquitoes, valence is switched and activation of the orthologous receptor conveys attraction. Reverse chemical ecology enables the identification of inhibitory odorants to reduce attraction of mosquitoes to skin.
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Martin F, Alcorta E. Measuring activity in olfactory receptor neurons in Drosophila: Focus on spike amplitude. JOURNAL OF INSECT PHYSIOLOGY 2016; 95:23-41. [PMID: 27614176 DOI: 10.1016/j.jinsphys.2016.09.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 09/01/2016] [Accepted: 09/02/2016] [Indexed: 06/06/2023]
Abstract
Olfactory responses at the receptor level have been thoroughly described in Drosophila melanogaster by electrophysiological methods. Single sensilla recordings (SSRs) measure neuronal activity in intact individuals in response to odors. For sensilla that contain more than one olfactory receptor neuron (ORN), their different spontaneous spike amplitudes can distinguish each signal under resting conditions. However, activity is mainly described by spike frequency. Some reports on ORN response dynamics studied two components in the olfactory responses of ORNs: a fast component that is reflected by the spike frequency and a slow component that is observed in the LFP (local field potential, the single sensillum counterpart of the electroantennogram, EAG). However, no apparent correlation was found between the two elements. In this report, we show that odorant stimulation produces two different effects in the fast component, affecting spike frequency and spike amplitude. Spike amplitude clearly diminishes at the beginning of a response, but it recovers more slowly than spike frequency after stimulus cessation, suggesting that ORNs return to resting conditions long after they recover a normal spontaneous spike frequency. Moreover, spike amplitude recovery follows the same kinetics as the slow voltage component measured by the LFP, suggesting that both measures are connected. These results were obtained in ab2 and ab3 sensilla in response to two odors at different concentrations. Both spike amplitude and LFP kinetics depend on odorant, concentration and neuron, suggesting that like the EAG they may reflect olfactory information.
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Affiliation(s)
- Fernando Martin
- Department of Functional Biology, Faculty of Medicine, University of Oviedo, Oviedo, Spain
| | - Esther Alcorta
- Department of Functional Biology, Faculty of Medicine, University of Oviedo, Oviedo, Spain.
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Entz M, George SA, Zeitz MJ, Raisch T, Smyth JW, Poelzing S. Heart Rate and Extracellular Sodium and Potassium Modulation of Gap Junction Mediated Conduction in Guinea Pigs. Front Physiol 2016; 7:16. [PMID: 26869934 PMCID: PMC4735342 DOI: 10.3389/fphys.2016.00016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 01/12/2016] [Indexed: 11/29/2022] Open
Abstract
Background: Recent studies suggested that cardiac conduction in murine hearts with narrow perinexi and 50% reduced connexin43 (Cx43) expression is more sensitive to relatively physiological changes of extracellular potassium ([K+]o) and sodium ([Na+]o). Purpose: Determine whether similar [K+]o and [Na+]o changes alter conduction velocity (CV) sensitivity to pharmacologic gap junction (GJ) uncoupling in guinea pigs. Methods: [K+]o and [Na+]o were varied in Langendorff perfused guinea pig ventricles (Solution A: [K+]o = 4.56 and [Na+]o = 153.3 mM. Solution B: [K+]o = 6.95 and [Na+]o = 145.5 mM). Gap junctions were inhibited with carbenoxolone (CBX) (15 and 30 μM). Epicardial CV was quantified by optical mapping. Perinexal width was measured with transmission electron microscopy. Total and phosphorylated Cx43 were evaluated by western blotting. Results: Solution composition did not alter CV under control conditions or with 15μM CBX. Decreasing the basic cycle length (BCL) of pacing from 300 to 160 ms decreased CV uniformly with both solutions. At 30 μM CBX, a change in solution did not alter CV either longitudinally or transversely at BCL = 300 ms. However, reducing BCL to 160 ms caused CV to decrease more in hearts perfused with Solution B than A. Solution composition did not alter perinexal width, nor did it change total or phosphorylated serine 368 Cx43 expression. These data suggest that the solution dependent CV changes were independent of altered perinexal width or GJ coupling. Action potential duration was always shorter in hearts perfused with Solution B than A, independent of pacing rate and/or CBX concentration. Conclusions: Increased heart rate and GJ uncoupling can unmask small CV differences caused by changing [K+]o and [Na+]o. These data suggest that modulating extracellular ionic composition may be a novel anti-arrhythmic target in diseases with abnormal GJ coupling, particularly when heart rate cannot be controlled.
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Affiliation(s)
- Michael Entz
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA; Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State UniversityRoanoke, VA, USA
| | - Sharon A George
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA; Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State UniversityRoanoke, VA, USA
| | - Michael J Zeitz
- Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State University Roanoke, VA, USA
| | - Tristan Raisch
- Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State UniversityRoanoke, VA, USA; Translational Biology, Medicine, and Health, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA
| | - James W Smyth
- Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State UniversityRoanoke, VA, USA; Department of Biological Sciences, College of Science, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA
| | - Steven Poelzing
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA; Virginia Tech Carilion Research Institute and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State UniversityRoanoke, VA, USA; Department of Biological Sciences, College of Science, Virginia Polytechnic Institute and State UniversityBlacksburg, VA, USA
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12
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George SA, Poelzing S. Cardiac conduction in isolated hearts of genetically modified mice--Connexin43 and salts. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:189-98. [PMID: 26627143 DOI: 10.1016/j.pbiomolbio.2015.11.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/13/2015] [Accepted: 11/23/2015] [Indexed: 10/22/2022]
Abstract
Physiologic variations in perfusate composition have been identified as a new and important modulator of cardiac conduction velocity (CV), particularly when gap junctions (GJ) are reduced. We recently demonstrated in ex vivo hearts that perfusates with low sodium and high potassium preferentially slow ventricular CV in mice genetically engineered to express 50% less of the gap junction protein, connexin43 (Cx43). We also reported the possible role of calcium in modulating CV. In this review we discuss previous murine studies that explored the CV-GJ relationship in isolated mouse heart preparations with approximately 50% reduced Cx43. Studies were grouped according to the type of perfusate utilized, and CV during GJ uncoupling was compared. Studies in Group A preferentially used perfusates with low sodium, high potassium and non-physiologic calcium, and found CV slows and arrhythmias increase in mouse hearts with reduced Cx43. Studies in Group B used solutions with high sodium, low potassium and physiologic calcium, and did not observe CV slowing nor increased arrhythmia risk with loss of Cx3. Studies in Group C used solutions with low sodium, low potassium, physiologic calcium, creatine, taurine, and insulin. CV slowing was not observed, nor was arrhythmia risk increased with loss of Cx43. We suggest that perfusate ion composition may be a major determinant of whether CV slows when Cx43 is reduced. Furthermore, the review of these studies highlights important theoretical developments in the understanding of cardiac conduction and suggests that ionic milieu can conceal electrophysiologic remodeling secondary to reduced Cx43 expression as occurs in many cardiac diseases.
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Affiliation(s)
- Sharon A George
- Department of Biomedical Engineering and Mechanics, Virginia Tech Carilion Research Institute, and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
| | - Steven Poelzing
- Department of Biomedical Engineering and Mechanics, Virginia Tech Carilion Research Institute, and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
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Su CY, Wang JW. Modulation of neural circuits: how stimulus context shapes innate behavior in Drosophila. Curr Opin Neurobiol 2014; 29:9-16. [PMID: 24801064 DOI: 10.1016/j.conb.2014.04.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 04/03/2014] [Accepted: 04/10/2014] [Indexed: 11/25/2022]
Abstract
Remarkable advances have been made in recent years in our understanding of innate behavior and the underlying neural circuits. In particular, a wealth of neuromodulatory mechanisms have been uncovered that can alter the input-output relationship of a hereditary neural circuit. It is now clear that this inbuilt flexibility allows animals to modify their behavioral responses according to environmental cues, metabolic demands and physiological states. Here, we discuss recent insights into how modulation of neural circuits impacts innate behavior, with a special focus on how environmental cues and internal physiological states shape different aspects of feeding behavior in Drosophila.
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Affiliation(s)
- Chih-Ying Su
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, United States
| | - Jing W Wang
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, United States.
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