Chapter Category: Channels and Transporters

From the book Insect Nicotinic Acetylcholine Receptors

Identification of Critical Elements Determining Toxins and Insecticides Affinity, Ligand Binding Domains and Channel Properties

Hélène Tricoire–Leignel and Steeve H. Thany

Insect nicotinic acetylcholine receptors have been objects of attention since the discovery of neonicotinoid insecticides. Mutagenesis studies have revealed that, although the detailed subunit composition of insect nicotinic acetylcholine receptors subtypes eludes us, the framework provided by mutagenesis analysis makes a picture of the subunits involved in the ligand binding and channel properties. In fact, many residues that line the channel or bind to the ligand seemed to be strongly conserved in particular in the N‑terminal extracellular region and the second transmembrane domain which constitutes the ion‑conducting pathway supporting the flux of ions as well as their discrimination. In fact, the positions are carried by loops B and C, respectively, which contain amino acids directly contributing to the acetylcholine binding site. Mutation of these residues accounts for insect resistance to neonicotinoid insecticides such as imidacloprid or a loss of specific binding. The discovery of the same mutation at homologous residues in different insect species or its conservation raises the intriguing question of whether a single mutation is essential to generate a resistance phenotype or whether some subunit confer insensitivity to ligand. Consequently, recent finding using information from Torpedo marmorata α1 subunit and soluble Aplysia californica and Lymnae stagnalis acetylcholine binding proteins from crystallization suggest that insect nAChR subunits had contributing amino acids in the agonist site structure which participate to affinity and pharmacological properties of these receptors. These new range of data greatly facilitate the understanding of toxin‑nAChR interactions and the neonicotinoid binding and selectivity.
  • ISBN: 978-1-4419-6444-1
  • Publication date: May 15, 2010
  • Series: Intelligence Unit
Taken from the book

Insect Nicotinic Acetylcholine Receptors

Edited by: Steeve Herve Thany

More chapters from the book:

Diversity of Insect Nicotinic Acetylcholine Receptor Subunits
Andrew K. Jones and David B. Sattelle

Nicotinic acetylcholine receptors (nAChRs) are ligand‑gated ion channels that mediate fast synaptic transmission in the insect nervous system and are targets of a major group of insecticides, the neonicotinoids. They consist of five subunits arranged around a central ion channel. Since the...

Characterisation of Insect Nicotinic Acetylcholine Receptors by Heterologous Expression
Neil Millar and Stuart J. Lansdell

As with other neurotransmitter receptors and ion channels, characterisation of nicotinic acetylcholine receptors (nAChRs) has relied heavily on studies conducted with cloned receptors expressed in artificial expression systems. Although much has been achieved in recent years by such studies,...

State of the Art on Insect Nicotinic Acetylcholine Receptor Function in Learning and Memory
Monique Gauthier

Acetylcholine is the most abundant excitatory neurotransmitter in the insect brain and the most numerous acetylcholine receptors are the nicotinic ones (nAChRs). The genome sequencing of diverse insect species has demonstrated the existence of at least 10 nAChR genes coding for α and β...

The Evolution of Pentameric Ligand‑Gated Ion Channels
Joseph A. Dent

Fast, ionotropic neurotransmission mediated by ligand‑gated ion channels is essential for timely behavioral responses in multicellular organisms. Metazoa employ more ionotropic neurotransmitters in more types of synapses, inhibitory or excitatory, than is generally appreciated. It is becoming...

Ecotoxicity of Neonicotinoid Insecticides to Bees
Axel Decourtye and James Devillers

This paper reviews the available data on the toxicity of neonicotinoid insecticides to bees that are the prominent and the most economically important group of pollinators worldwide. Classical and new methods developed to take into account the characteristics and different types of effects of the...

Identification of Critical Elements Determining Toxins and Insecticides Affinity, Ligand Binding Domains and Channel Properties
Hélène Tricoire–Leignel and Steeve H. Thany

Insect nicotinic acetylcholine receptors have been objects of attention since the discovery of neonicotinoid insecticides. Mutagenesis studies have revealed that, although the detailed subunit composition of insect nicotinic acetylcholine receptors subtypes eludes us, the framework provided by...

Electrophysiological Studies and Pharmacological Properties of Insect Native Nicotinic Acetylcholine Receptors
Steeve Herve Thany

The existence of several nicotinic acetylcholine receptor genes in insects suggests that many nicotinic receptor subtypes are present, but the identification and characterization of these subtypes in native neurons has been limited. Their pharmacological properties came from electrophysiological...

Identification of Cholinergic Synaptic Transmission in the Insect Nervous System
Steeve Thany, Hélène Tricoire–Leignel and Bruno Lapied

A major criteria initially used to localize cholinergic neuronal elements in nervous systems tissues that involve acetylcholine (ACh) as neurotransmitter is mainly based on immunochemical studies using choline acetyltransferase (ChAT), an enzyme which catalyzes ACh biosynthesis and the ACh...

Neonicotinoid Insecticides
Historical Evolution and Resistance Mechanisms
Steeve Thany

The use of neonicotinoid insecticides has grown considerably since their introduction in 1990s. They are used extensively for the control of agriculturally important crop pests and also in the control of cat and dog fleas. Imidacloprid exploited through an elaborated structural and substituent...

Advertisements