scholarly journals More than meets the IR: the expanding roles of variant Ionotropic Glutamate Receptors in sensing odor, taste, temperature and moisture

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 1753 ◽  
Author(s):  
Lena van Giesen ◽  
Paul A. Garrity
Keyword(s):  
Glutamate Receptors ◽  
Glutamate Receptor ◽  
Olfactory Receptors ◽  
Sensory Transduction ◽  
Ionotropic Glutamate Receptors ◽  
Ionotropic Glutamate Receptor ◽  
Ecological Significance ◽  
Ionotropic Receptors ◽  
Sensory Modalities ◽  
Receptor Family

The ionotropic receptors (IRs) are a branch of the ionotropic glutamate receptor family and serve as important mediators of sensory transduction in invertebrates. Recent work shows that, though initially studied as olfactory receptors, the IRs also mediate the detection of taste, temperature, and humidity. Here, we summarize recent insights into IR evolution and its potential ecological significance as well as recent advances in our understanding of how IRs contribute to diverse sensory modalities.

scholarly journals Functional properties of insect olfactory receptors: ionotropic receptors and odorant receptors

2021 ◽  
Vol 383 (1) ◽  
pp. 7-19
Author(s):  
Dieter Wicher ◽  
Fabio Miazzi
Keyword(s):  
Functional Properties ◽  
Olfactory Receptors ◽  
Odorant Receptors ◽  
Current View ◽  
Ionotropic Glutamate Receptor ◽  
Specific Receptor ◽  
Ionotropic Receptors ◽  
Receptor Proteins ◽  
Evolution Function ◽  
Receptor Family

AbstractThe majority of insect olfactory receptors belong to two distinct protein families, the ionotropic receptors (IRs), which are related to the ionotropic glutamate receptor family, and the odorant receptors (ORs), which evolved from the gustatory receptor family. Both receptor types assemble to heteromeric ligand-gated cation channels composed of odor-specific receptor proteins and co-receptor proteins. We here present in short the current view on evolution, function, and regulation of IRs and ORs. Special attention is given on how their functional properties can meet the environmental and ecological challenges an insect has to face.

scholarly journals The Structure and Function of Ionotropic Receptors in Drosophila

2021 ◽  
Vol 13 ◽  
Author(s):  
Lina Ni
Keyword(s):  
Glutamate Receptors ◽  
Structure And Function ◽  
Ionotropic Glutamate Receptors ◽  
Animal Kingdom ◽  
Ionotropic Receptors ◽  
Ir Studies ◽  
Major Branch ◽  
Future Direction ◽  
And Function ◽  
Peripheral Sensory

Ionotropic receptors (IRs) are a highly divergent subfamily of ionotropic glutamate receptors (iGluR) and are conserved across Protostomia, a major branch of the animal kingdom that encompasses both Ecdysozoa and Lophothrochozoa. They are broadly expressed in peripheral sensory systems, concentrated in sensory dendrites, and function in chemosensation, thermosensation, and hygrosensation. As iGluRs, four IR subunits form a functional ion channel to detect environmental stimuli. Most IR receptors comprise individual stimulus-specific tuning receptors and one or two broadly expressed coreceptors. This review summarizes the discoveries of the structure of IR complexes and the expression and function of each IR, as well as discusses the future direction for IR studies.

scholarly journals Distinct combinations of variant ionotropic glutamate receptors mediate thermosensation and hygrosensation in Drosophila

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Zachary A Knecht ◽  
Ana F Silbering ◽  
Lina Ni ◽  
Mason Klein ◽  
Gonzalo Budelli ◽  
...  
Keyword(s):  
Glutamate Receptors ◽  
Recent Work ◽  
Sensory Neurons ◽  
Behavioral Responses ◽  
Ionotropic Glutamate Receptors ◽  
Neuronal Responses ◽  
Common Component ◽  
Ionotropic Receptors ◽  
Dry Air ◽  
Discrete Population

Ionotropic Receptors (IRs) are a large subfamily of variant ionotropic glutamate receptors present across Protostomia. While these receptors are most extensively studied for their roles in chemosensory detection, recent work has implicated two family members, IR21a and IR25a, in thermosensation in Drosophila. Here we characterize one of the most evolutionarily deeply conserved receptors, IR93a, and show that it is co-expressed and functions with IR21a and IR25a to mediate physiological and behavioral responses to cool temperatures. IR93a is also co-expressed with IR25a and a distinct receptor, IR40a, in a discrete population of sensory neurons in the sacculus, a multi-chambered pocket within the antenna. We demonstrate that this combination of receptors is required for neuronal responses to dry air and behavioral discrimination of humidity differences. Our results identify IR93a as a common component of molecularly and cellularly distinct IR pathways important for thermosensation and hygrosensation in insects.

Development of glutamatergic synapses in the rat retina: The postnatal expression of ionotropic glutamate receptor subunits

2002 ◽  
Vol 19 (1) ◽  
pp. 1-13 ◽  
Author(s):  
IRIS HACK ◽  
PETER KOULEN ◽  
LEO PEICHL ◽  
JOHANN HELMUT BRANDSTÄTTER
Keyword(s):  
Glutamate Receptors ◽  
Glutamate Receptor ◽  
Plexiform Layer ◽  
Ultrastructural Localization ◽  
Kainate Receptors ◽  
Kainate Receptor ◽  
Ionotropic Glutamate Receptor ◽  
Inner Plexiform Layer ◽  
Rat Retina ◽  
Kainate Receptor Subunits

We examined the distribution of the AMPA glutamate receptor subunits GluR1 to GluR4, of the kainate receptor subunits GluR6/7 and KA2, and of the glutamate receptor subunits δ1/2, during postnatal development of the rat retina by immunocytochemistry and light microscopy using receptor subunit specific antisera. The various ionotropic glutamate receptor subunits were expressed early in postnatal rat retina, and most of the subunits, with the exception of δ1/2, were found in both synaptic layers of rat retina. The glutamate receptor subunits studied showed differences in their time of appearance, their spatial distribution patterns, and in their expression levels in the developing rat retina. Interestingly, most of the AMPA receptor subunits were expressed earlier than the kainate receptor subunits in the two synaptic layers of the retina, indicating that AMPA glutamate receptors play an important role in early postnatal glutamatergic synaptic transmission. We also studied the ultrastructural localization of the AMPA glutamate receptor subunits GluR1 to GluR4 by immunocytochemistry and electron microscopy in the inner plexiform layer of the mature rat retina. Most of the subunits were found postsynaptic to the ribbon synapses of OFF-cone, ON-cone, and rod bipolar cells. The results of this study suggest an involvement of ionotropic glutamate receptors in processes of synaptic maturation and the formation of synaptic circuitries in the developing plexiform layers of the retina. Furthermore, AMPA and kainate receptors play a role in synaptic processing and in the development of both the scotopic and photopic pathways in the rat retina.

scholarly journals Ionotropic glutamate receptors in the external lateral parabrachial nucleus participate in processing cardiac sympathoexcitatory reflexes

2012 ◽  
Vol 302 (7) ◽  
pp. H1444-H1453 ◽  
Author(s):  
Liang-Wu Fu ◽  
Zhi-Ling Guo ◽  
John C. Longhurst
Keyword(s):  
Glutamate Receptors ◽  
Glutamate Receptor ◽  
Ampa Receptors ◽  
Repeated Administration ◽  
Parabrachial Nucleus ◽  
Ionotropic Glutamate Receptors ◽  
Reflex Responses ◽  
Lateral Parabrachial Nucleus ◽  
Artificial Cerebrospinal Fluid ◽  
Before And After

Stimulation of cardiac sympathetic afferents during myocardial ischemia with metabolites such as bradykinin (BK) evokes sympathoexcitatory reflex responses and activates neurons in the external lateral parabrachial nucleus (elPBN). The present study tested the hypothesis that this region in the pons processes sympathoexcitatory cardiac reflexes through an ionotropic glutamate receptor mechanism. The ischemic metabolite BK (0.1–1 μg) was injected into the pericardial space of anesthetized and bilaterally vagotomized or intact cats. Hemodynamic and renal sympathetic nerve activity (RSNA) responses to repeated administration of BK before and after unilateral 50-nl microinjections of kynurenic acid (Kyn; 25 mM), 2-amino-5-phosphonopentanoic acid (AP5; 25 mM), and 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzol(F)quinoxaline (NBQX; 10 mM) into the elPBN were recorded. Intrapericardial BK evoked significant increases in mean arterial pressure (MAP) and RSNA in seven vagotomized cats. After blockade of glutamate receptors with the nonselective glutamate receptor antagonist Kyn, the BK-evoked reflex increases in MAP (50 ± 6 vs. 29 ± 2 mmHg) and RSNA (59 ± 8.6 vs. 29 ± 4.7%, before vs. after) were significantly attenuated. The BK-evoked responses returned to pre-Kyn levels 85 min after the application of Kyn. Similarly, BK-evoked reflex responses were reversibly attenuated by blockade of glutamate N-methyl-d-aspartate (NMDA) receptors with AP5 ( n = 5) and α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors with NBQX ( n = 5). In contrast, we observed that the repetitive administration of BK evoked consistent reflex responses including MAP and RSNA before and after microinjection of 50 nl of the artificial cerebrospinal fluid vehicle into the elPBN in five animals. Microinjection of glutamate receptor antagonists into regions outside the elPBN did not alter BK-induced reflex responses. Microinjection of Kyn into the elPBN reversibly attenuated BK-induced reflex responses in four vagus intact animals. These data are the first to show that NMDA and AMPA ionotropic glutamate receptors in the elPBN play an important role in processing cardiac excitatory reflex responses.

scholarly journals Distinct combinations of variant ionotropic glutamate 1 receptors mediate thermosensation and hygrosensation in Drosophila

2016 ◽  
Author(s):  
Zachary A. Knecht ◽  
Ana F. Silbering ◽  
Lina Ni ◽  
Mason Klein ◽  
Gonzalo Budelli ◽  
...  
Keyword(s):  
Glutamate Receptors ◽  
Recent Work ◽  
Sensory Neurons ◽  
Behavioral Responses ◽  
Ionotropic Glutamate Receptors ◽  
Neuronal Responses ◽  
Common Component ◽  
Ionotropic Receptors ◽  
Dry Air ◽  
Discrete Population

AbstractIonotropic Receptors (IRs) are a large subfamily of variant ionotropic glutamate receptors present across Protostomia. While these receptors are most extensively studied for their roles in chemosensory detection in insects, recent work has implicated two family members, IR21a and IR25a, in thermosensation in Drosophila. Here we characterize one of the most deeply conserved receptors, IR93a, and show that it is co-expressed and functions with IR21a and IR25a to mediate physiological and behavioral responses to cool temperatures. IR93a is also co-expressed with IR25a and a distinct receptor, IR40a, in a discrete population of sensory neurons in the sacculus, a multi-chambered pocket within the antenna. We demonstrate that this combination of receptors is important for neuronal responses to dry air and behavioral discrimination of humidity differences. Our results identify IR93a as a common component of molecularly and cellularly distinct IR pathways underlying thermosensation and hygrosensation in insects.

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