Insecticide Actions on Gaba Receptors and Voltage-Dependent Chloride Channels

1989 ◽  
pp. 1-11 ◽  
Author(s):  
Mohyee E. Eldefrawi ◽  
Amira T. Eldefrawi
Keyword(s):  
Gaba Receptors ◽  
Chloride Channels ◽  
Voltage Dependent

Ion channels and G protein-coupled receptors as targets for invertebrate pest control: from past challenges to practical insecticides

2021 ◽  
Author(s):  
Yoshihisa Ozoe
Keyword(s):  
Ion Channels ◽  
G Protein ◽  
Pest Control ◽  
Gaba Receptors ◽  
Chloride Channels ◽  
Structural Changes ◽  
G Protein Coupled Receptors ◽  
Octopamine Receptors ◽  
Sites Of Action ◽  
G Protein Coupled

Abstract In the late 1970s, we discovered that toxic bicyclic phosphates inhibit the generation of miniature inhibitory junction potentials, implying their antagonism of γ-aminobutyric acid (GABA) receptors (GABARs; GABA-gated chloride channels). This unique mode of action provided a strong incentive for our research on GABARs in later years. Furthermore, minor structural changes conferred insect GABAR selectivity to this class of compounds, convincing us of the possibility of GABARs as targets for insecticides. Forty years later, third-generation insecticides acting as allosteric modulator antagonists at a distinctive site of action in insect GABARs were developed. G protein-coupled receptors (GPCRs) are also promising targets for pest control. We characterized phenolamine receptors functionally and pharmacologically. Of the tested receptors, β-adrenergic-like octopamine receptors were revealed to be the most sensitive to the acaricide/insecticide amitraz. Given the presence of multiple sites of action, ion channels and GPCRs remain potential targets for invertebrate pest control.

Homomeric RDL and Heteromeric RDL/LCCH3 GABA Receptors in the Honeybee Antennal Lobes: Two Candidates for Inhibitory Transmission in Olfactory Processing

2010 ◽  
Vol 103 (1) ◽  
pp. 458-468 ◽  
Author(s):  
Julien Pierre Dupuis ◽  
Michaël Bazelot ◽  
Guillaume Stéphane Barbara ◽  
Sandrine Paute ◽  
Monique Gauthier ◽  
...  
Keyword(s):  
Information Processing ◽  
Chloride Channel ◽  
Gaba Receptors ◽  
Gaba Receptor ◽  
Chloride Channels ◽  
Physiological Role ◽  
Inhibitory Transmission ◽  
Olfactory Information ◽  
Whole Cell Patch Clamp ◽  
Inward Currents

γ-Aminobutyric acid (GABA)–gated chloride channel receptors are abundant in the CNS, where their physiological role is to mediate fast inhibitory neurotransmission. In insects, this inhibitory transmission plays a crucial role in olfactory information processing. In an effort to understand the nature and properties of the ionotropic receptors involved in these processes in the honeybee Apis mellifera, we performed a pharmacological and molecular characterization of GABA-gated channels in the primary olfactory neuropile of the honeybee brain—the antennal lobe (AL)—using whole cell patch-clamp recordings coupled with single-cell RT-PCR. Application of GABA onto AL cells at −110 mV elicited fast inward currents, demonstrating the existence of ionotropic GABA-gated chloride channels. Molecular analysis of the GABA-responding cells revealed that both subunits RDL and LCCH3 were expressed out of the three orthologs of Drosophila melanogaster GABA-receptor subunits encoded within the honeybee genome (RDL, resistant to dieldrin; GRD, GABA/glycine-like receptor of Drosophila ; LCCH3, ligand-gated chloride channel homologue 3), opening the door to possible homo- and/or heteromeric associations. The resulting receptors were activated by insect GABA-receptor agonists muscimol and CACA and blocked by antagonists fipronil, dieldrin, and picrotoxin, but not bicuculline, displaying a typical RDL-like pharmacology. Interestingly, increasing the intracellular calcium concentration potentiated GABA-elicited currents, suggesting a modulating effect of calcium on GABA receptors possibly through phosphorylation processes that remain to be determined. These results indicate that adult honeybee AL cells express typical RDL-like GABA receptors whose properties support a major role in synaptic inhibitory transmission during olfactory information processing.

Attenuation of endothelin effects by a chloride channel inhibitor, indanyloxyacetic acid

1992 ◽  
Vol 262 (5) ◽  
pp. F799-F806 ◽  
Author(s):  
T. Takenaka ◽  
M. Epstein ◽  
H. Forster ◽  
D. W. Landry ◽  
K. Iijima ◽  
...  
Keyword(s):  
Chloride Channel ◽  
Chloride Channels ◽  
Specific Binding ◽  
Fluorescein Isothiocyanate ◽  
Cytosolic Calcium ◽  
Membrane Depolarization ◽  
Voltage Dependent ◽  
Voltage Dependent Calcium Channels ◽  
Afferent Arterioles ◽  
Subsequent Activation

We have recently proposed that the actions of endothelin (ET) are in part mediated by opening of chloride channels (K. Iijima, L. Lin, A. Nasjletti, and M. S. Goligorsky. Am. J. Physiol. 260 (Cell Physiol. 29: C982-C992, 1991). In the present study the ability of a chloride channel inhibitor, an indanyloxyacetic acid (IAA-94), to block ET-induced effects was examined in cultured vascular smooth muscle cells (VSMC) by spectrofluorometry and direct videomicroscopic visualization of the renal microcirculation in isolated perfused hydronephrotic kidneys (IPHK). A fluorescein isothiocyanate (FITC)-labeled IAA-94 analogue showed specific binding to VSMC. IAA-94 (30 microM) neither affected basal cytosolic calcium concentration ([Ca2+]i) in VSMC nor peak response to ET, but it significantly curtailed sustained elevation of [Ca2+]i (half-time recovery was 147 +/- 23 vs. 248 +/- 33 s in control, P less than 0.05). IAA-94 blunted ET-induced membrane depolarization from 24.5 +/- 3.3 to 8.0 +/- 1.8 mV. In IPHK, ET constricted afferent arterioles (AA) by 29 +/- 2% (18.7 +/- 0.8 to 13.2 +/- 0.6 microns, P less than 0.001). Isradipine reversed this ET-induced vasoconstriction. Pretreatment with IAA-94 did not alter AA diameter, but markedly attenuated ET-induced AA constriction (reduction of AA diameters by only 9 +/- 2%, P less than 0.001). The subsequent addition of isradipine (0.1-1 microM) did not further dilate AA. Our data indicate that IAA-94 markedly attenuates AA vasoconstriction elicited by ET and suggest that ET-induced opening of chloride channels, membrane depolarization, and subsequent activation of voltage-dependent calcium channels contribute to the vasoconstrictor mechanisms of this peptide.

scholarly journals Mechanism of voltage-dependent gating in skeletal muscle chloride channels

1996 ◽  
Vol 71 (2) ◽  
pp. 695-706 ◽  
Author(s):  
C. Fahlke ◽  
A. Rosenbohm ◽  
N. Mitrovic ◽  
A.L. George ◽  
R. Rüdel
Keyword(s):  
Skeletal Muscle ◽  
Chloride Channels ◽  
Voltage Dependent

Inositol trisphosphate activates a voltage-dependent calcium influx in Xenopus oocytes

1987 ◽  
Vol 231 (1262) ◽  
pp. 27-36 ◽  
Keyword(s):  
Chloride Channels ◽  
Calcium Influx ◽  
Inositol Trisphosphate ◽  
Ringer Solution ◽  
Chloride Ions ◽  
Bathing Solution ◽  
Calcium Dependent ◽  
Large Numbers ◽  
Voltage Dependent ◽  
Oocyte Membrane

Injection of inositol trisphosphate (IP 3 ) into oocytes of Xenopus laevis induces the appearance of a transient inward ( T in ) current on hyper­polarization of the membrane. This current is carried largely by chloride ions, but is shown to depend on extracellular calcium, because it is abolished by removal of calcium in the bathing fluid or by addition of manganese. Recordings with aequorin as an intracellular calcium indi­cator show that a calcium influx is activated by hyperpolarization after intracellular injection of IP 3 as well as after activation of neurotrans­mitter receptors thought to mediate a rise in IP 3 . Furthermore, by substituting barium for calcium in the bathing solution, inward barium currents can be recorded during hyperpolarization. We conclude that intracellular IP 3 modulates the activity of a class of calcium channels, so as to allow an influx of calcium on hyperpolarization. In normal Ringer solution this then leads to the generation of a chloride current, because of the large numbers of calcium-dependent chloride channels in the oocyte membrane.

scholarly journals Myotonia-related mutations in the distal C-terminus of ClC-1 and ClC-0 chloride channels affect the structure of a poly-proline helix

2007 ◽  
Vol 403 (1) ◽  
pp. 79-87 ◽  
Author(s):  
María J. Macías ◽  
Oscar Teijido ◽  
Giovanni Zifarelli ◽  
Pau Martin ◽  
Ximena Ramirez-Espain ◽  
...  
Keyword(s):  
Chloride Channels ◽  
Structural Changes ◽  
Surface Expression ◽  
Muscle Fibres ◽  
Coding Region ◽  
Protein Coding ◽  
C Terminus ◽  
Voltage Dependent ◽  
Common Gate ◽  
Spectroscopy Studies

Myotonia is a state of hyperexcitability of skeletal-muscle fibres. Mutations in the ClC-1 Cl− channel cause recessive and dominant forms of this disease. Mutations have been described throughout the protein-coding region, including three sequence variations (A885P, R894X and P932L) in a distal C-terminal stretch of residues [CTD (C-terminal domain) region] that are not conserved between CLC proteins. We show that surface expression of these mutants is reduced in Xenopus oocytes compared with wild-type ClC-1. Functional, biochemical and NMR spectroscopy studies revealed that the CTD region encompasses a segment conserved in most voltage-dependent CLC channels that folds with a secondary structure containing a short type II poly-proline helix. We found that the myotonia-causing mutation A885P disturbs this structure by extending the poly-proline helix. We hypothesize that this structural modification results in the observed alteration of the common gate that acts on both pores of the channel. We provide the first experimental investigation of structural changes resulting from myotonia-causing mutations.

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