Nicotinic-acetylcholine receptors are functionally coupled to the nitric oxide/cGMP-pathway in insect neurons (original) (raw)
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Activation of nicotinic acetylcholine receptors on cultured Drosophila and other insect neurones
The Journal of physiology, 1993
1. Using whole-cell and single channel recordings, we have examined the properties of acetylcholine (ACh)-activated currents in neurones from larval and pupal Drosophila melanogaster (fruit fly), larval and embryonic Musca domestica (house fly), and nymphal Schistocerca gregaria (locust). 2. In all preparations, single channel recordings revealed two major classes of ACh-activated channels, with average conductances of approximately 32 and 59 pS. 3. At ACh concentrations from 1 to 10 microM, channel activity in Drosophila larval neurones occurs in bursts with an average of 1-2 openings. Open times and burst durations are described by one or two exponentials. Burst durations for the 32 pS channel (approximately 3 ms, slow component) were longer than those for the 59 pS channel (approximately 1.0 ms). The mean open interval duration for the 32 pS channel (slow component) was also longer than that of the 59 pS channel. 4. At high ACh (20-200 microM) concentrations, bursts of the smalle...
Exploring the pharmacological properties of insect nicotinic acetylcholine receptors
Trends in Pharmacological Sciences, 2007
Glossary a-Bungarotoxin (a-Bgt): toxin from snake venom. a-Bgt binding is considered to represent the distribution of a7-subunit-containing nACh receptors. DEG: degeneration of certain neurons. In Caenorhabditis elegans, there are 42 different nACh receptor subunits, including the deg-3 group. des-2 is another gene in this group. DES: degeneration suppressor. Mutations in the gene encoding this protein suppress the degeneration caused by deg-3. Drosophila Da7 mutant: excisions of P elements in the Da7 subunits lead to several alleles. nACh receptor subtype: a specific combination of identical (homomeric) or different (heteromeric) subunits that forms a pentameric nACh receptor.
Molecular pharmacology, 2001
Although molecular biology provides new insights into the subunit compositions and the stoichiometries of insect neuronal nicotinic acetylcholine receptors (nAChRs), our knowledge about the phosphorylation/dephosphorylation mechanisms of native neuronal nAChRs is limited. The regulation of alpha-bungarotoxin-resistant nAChRs was studied on dissociated adult dorsal unpaired median neurons isolated from the terminal abdominal ganglion of the cockroach Periplaneta americana, using whole-cell, patch-clamp technique. Under 0.5 microM alpha-bungarotoxin treatment, pressure ejection application of nicotine or acetylcholine onto the cell body induced an inward current exhibiting a biphasic current-voltage relationship. We found that two distinct components underlying the biphasic curve differed in their ionic permeability and pharmacology (one being sensitive to d-tubocurarine, and the other affected only by mecamylamine and alpha-conotoxin ImI). This indicated that two types of alpha-bunga...
Neuroscience Letters, 2012
The goal of the present study is to examine the agonist action of nornicotine on insect nicotinic acetylcholine receptors. Using patch-clamp techniques on cockroach dorsal unpaired median neurons, we demonstrated that nornicotine induced two distinct ionic currents named types 1 and 2. We found that alpha-bungarotoxin induced a rapid desensitization of type 1 currents whereas type 2 was completely blocked. Interestingly, types 1 and 2 currents were not blocked by the muscarinic antagonist, pirenzepine but by co-application of 1 M pirenzepine and 0.5 M alpha-bungarotoxin, suggesting that muscarinic receptors modulated nornicotine-induced current amplitudes. In addition, type 1 current amplitudes were strongly reduced by 20 M d-tubocurarine and 5 M mecamylamine which blocked the previously identified alpha-bungarotoxin-insensitive nAChR1 and nAChR2 receptors. Co-application of alpha-bungarotoxin with d-tubocurarine or mecamylamine completely blocked all ionic currents. We propose that types 1 and 2 currents are associated to several nicotinic receptors subtypes, including nAChR1 and nAChR2 receptors. Finally, we conclude that nornicotine could be used as an agonist to identify distinct insect nicotinic receptors.
Expression of a neuronal nicotinic acetylcholine receptor in insect and mammalian host cell systems
Neurochemical research, 2000
Different mammalian and insect somatic host cell systems were tested in their ability to express, fold, and assemble alpha7-type neuronal acetylcholine receptor (AChR) both at the transcriptional and translational level. For this purpose we employed clonal cell lines derived from the neural crest, such as PC12 cells from a rat adrenal pheochromocytoma, and GH3 cells isolated from a rat pituitary tumor, as well as non-neuronal cells such as NIH-3T3 fibroblasts from embryonic NIH Swiss mouse and Sf9 cells from ovary tissue of the Spodoptera frugiperda butterfly. Total RNA, isolated from either transfected or non-transfected PC12, GH3 or 3T3 cells, or recombinant AcNPV-infected and mock-infected Sf9 cells was analyzed by Northern blot. PC12 cells, which endogenously express alpha7 AChR, and all its heterologous alpha7-transfectant clones, exhibited variable but generally high amounts of a single transcript. GH3 and NIH-3T3 transfectant clones and recombinant AcNPV-infected Sf9 cells ex...
Invertebrate Neuroscience, 2008
In insects, acetylcholine (ACh) is the main neurotransmitter, and nicotinic acetylcholine receptors (nAChRs) mediate fast cholinergic synaptic transmission. In the honeybee, nAChRs are expressed in diverse structures including the primary olfactory centres of the brain, the antennal lobes (AL) and the mushroom bodies. Whole-cell, voltage-clamp recordings were used to characterize the nAChRs present on cultured AL cells from adult honeybee,
Neuronal nicotinic acetylcholine receptors: from the gene to the disease
Behavioural Brain Research, 2000
Although neuronal nicotinic acetylcholine receptors from insects have been reconstituted in vitro more than a decade ago, our knowledge about the subunit composition of native receptors as well as their functional properties still remains limited. Immunohistochemical evidence has suggested that two ␣ subunits, ␣-like subunit (ALS) and Drosophila ␣2 subunit (D␣2), are colocalized in the synaptic neuropil of the Drosophila CNS and therefore may be subunits of the same receptor complex. To gain further understanding of the composition of these nicotinic receptors, we have examined the possibility that a receptor may imbed more than one ␣ subunit using immunoprecipitations and electrophysiological investigations. Immunoprecipitation experiments of fly head extracts revealed that ALS-specific antibodies coprecipitate D␣2, and vice versa, and thereby suggest that these two ␣ subunits must be contained within the same receptor complex, a result that is supported by investigations of reconstituted receptors in Xenopus oocytes. Discrimination between binary (ALS/2 or D␣2/2) and ternary (ALS/D␣2/2) receptor complexes was made on the basis of their dose -response curve to acetylcholine as well as their sensitivity to ␣-bungarotoxin or dihydro--erythroidine. These data demonstrate that the presence of the two ␣ subunits within a single receptor complex confers new receptor properties that cannot be predicted from knowledge of the binary receptor's properties.
Neuronal nicotinic receptors in the locust Locusta migratoria
Journal of Biological …, 1998
We have identified five cDNA clones that encode nicotinic acetylcholine receptor (nAChR) subunits expressed in the nervous system of the locust Locusta migratoria. Four of the subunits are ligand-binding ␣ subunits, and the other is a structural  subunit. The existence of at least one more nAChR gene, probably encoding a  subunit, is indicated.
Journal of Experimental Biology, 1992
Mechanically isolated neuronal somata from the thoracic ganglia of the locust Locusta migratoria remain electrophysiologically viable under current-or voltage-clamp in vitro for many hours. Nicotine and muscarine evoke different responses when pressure-microapplied to these somata. The response to acetylcholine is mainly nicotinic but contains a small muscarinic component. The nicotinic (AChl) response is a rapid depolarisation accompanied by a decrease in membrane resistance. In voltage-clamped somata, the current mediating the AChl response is inward over the membrane potential range −30 to − 110 mV, decreasing with depolarisation and with a projected reversal potential of about +20 mV. The muscarinic (ACh2) response is a slow depolarisation accompanied by a decrease in membrane resistance. In voltage-clamped somata, the current mediating the ACh2 response is inward, decreasing to zero at potentials of −80 to −90 mV. The AChl response is evoked by nicotine, anabasine, tetramethyla...
The nicotinic receptors in the nervous system
Pharmacological Research Communications, 1988
Nicotinic acetylcholine receptors (AChRs) mediate chemical communication in many parts of the body, including neuromuscular junctions, autonomic ganglia and several areas of the brain. Their activation, by acetylcholine (ACh) released from nerve terminals, induces an influx of Na + ions and depolarization of the target cell. The function of AChR has been investigated by pharmacological, biochemical and reconstitution experiments, using as a model, the AChR purified from the electric organs of the Torpedo. These studies have provided a wealth of basic information techniques, and molecular probes which have been utilized to characterize other receptors classes and ion channels, which may share structural and functional properties with AChRs (Barnard et al., 1987). In the Central Nervous System (CNS), the presence of AChR has been postulated on the basis of pharmacological experiments, and the information available suggests that this molecule has different properties from those of muscle or Torpedo AChR. In the CNS of higher vertebrates AChRs are involved in different physiological functions as indicated by several observations on the effects of nicotinic agonists and antagonists on