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PLoS One
2016 Jan 01;111:e0146854. doi: 10.1371/journal.pone.0146854.
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Curiouser and Curiouser: The Macrocyclic Lactone, Abamectin, Is also a Potent Inhibitor of Pyrantel/Tribendimidine Nicotinic Acetylcholine Receptors of Gastro-Intestinal Worms.
Abongwa M
,
Buxton SK
,
Robertson AP
,
Martin RJ
.
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Nematode parasites may be controlled with drugs, but their regular application has given rise to concerns about the development of resistance. Drug combinations may be more effective than single drugs and delay the onset of resistance. A combination of the nicotinic antagonist, derquantel, and the macrocyclic lactone, abamectin, has been found to have synergistic anthelmintic effects against gastro-intestinal nematode parasites. We have observed in previous contraction and electrophysiological experiments that derquantel is a potent selective antagonist of nematode parasite muscle nicotinic receptors; and that abamectin is an inhibitor of the same nicotinic receptors. To explore these inhibitory effects further, we expressed muscle nicotinic receptors of the nodular worm, Oesophagostomum dentatum (Ode-UNC-29:Ode-UNC-63:Ode-UNC-38), in Xenopus oocytes under voltage-clamp and tested effects of abamectin on pyrantel and acetylcholine responses. The receptors were antagonized by 0.03 μM abamectin in a non-competitive manner (reduced Rmax, no change in EC50). This antagonism increased when abamectin was increased to 0.1 μM. However, when we increased the concentration of abamectin further to 0.3 μM, 1 μM or 10 μM, we found that the antagonism decreased and was less than with 0.1 μM abamectin. The bi-phasic effects of abamectin suggest that abamectin acts at two allosteric sites: one high affinity negative allosteric (NAM) site causing antagonism, and another lower affinity positive allosteric (PAM) site causing a reduction in antagonism. We also tested the effects of 0.1 μM derquantel alone and in combination with 0.3 μM abamectin. We found that derquantel on these receptors, like abamectin, acted as a non-competitive antagonist, and that the combination of derquantel and abamectin produced greater inhibition. These observations confirm the antagonistic effects of abamectin on nematode nicotinic receptors in addition to GluCl effects, and illustrate more complex effects of macrocyclic lactones that may be exploited in combinations with other anthelmintics.
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Fig 1. Structures of derquantel and abamectin.A: Structure of derquantel. B: Structure of abamectin. Abamectin is a mixture of avermectin B1a and avermectin B1b. Avermectin B1a differs from avermectin B1b by a functional group at the âRâ position, and makes up more than 80% of abamectin, while avermectin B1b makes up less than 20% of abamectin.
Fig 2. Acetylcholine and pyrantel concentration-response relationships for the Ode-UNC-29:Ode-UNC-63:Ode-UNC-38 receptor.A: Representative trace (inward currents, holding potential -60mV, from oocytes expressing Ode-UNC-29:Ode-UNC-63:Ode-UNC-38) following 10 seconds applications of different acetylcholine concentrations, from 0.1 μM to 100 μM. B: Representative trace (inward currents, holding potential -60mV, from oocytes expressing Ode-UNC-29:Ode-UNC-63:Ode-UNC-38) of the 10 seconds application of different pyrantel concentrations, from 0.03 μM to 10 μM. An initial 10 seconds application of 100 μM acetylcholine served as the control. C: Concentration-response plots for acetylcholine (n = 4, black) and pyrantel (n = 6, red). Results were normalized to 100 μM acetylcholine current responses and expressed as mean ± S.E.M.
Fig 3. Pyrantel concentration-response relationships in the presence of 0.03 μM and 0.1 μM abamectin.A: Representative trace (inward currents, holding potential -60mV, from oocytes expressing Ode-UNC-29:Ode-UNC-63:Ode-UNC-38) of the 10 seconds application of the control 100 μM acetylcholine, followed by a 10 minutes application of abamectin (0.03 μM) and finally, a 10 seconds application of different pyrantel concentrations in the continued presence of abamectin. B: Concentration-response plots for pyrantel in the absence (n = 6, red) and presence of 0.03 μM abamectin (n = 5, orange) and 0.1 μM abamectin (n = 6, dark blue). Results were normalized to 100 μM acetylcholine current responses and expressed as mean ± S.E.M. Notice 0.03 μM abamectin caused an inhibition of current responses to pyrantel, and this inhibition was greater with 0.1 μM abamectin.
Fig 4. Effects of increasing concentrations of abamectin (above 0.1 μM) on the pyrantel concentration-response plots.A: Concentration-response plots for pyrantel in the absence (n = 6, red) and presence of 0.1 μM abamectin (n = 6, dark blue); 0.3 μM abamectin (n = 5, dark green); 1 μM abamectin (n = 6, pink); 10 μM abamectin (n = 5, light blue). Results were normalized to 100 μM acetylcholine current responses and expressed as mean ± S.E.M. Increasing the concentration of abamectin from 0.1 μM to 0.3, 1 and 10 μM rather caused a reduction in the inhibition instead of a potentiation. B: Bar chart showing the mean ± S.E.M of the maximum current responses (Rmax) for pyrantel and the different abamectin concentrations. Rmax for 0.1 μM abamectin (n = 6, dark blue), 0.3 μM abamectin (n = 5, dark green), 1 μM abamectin (n = 6, pink) and 10 μM abamectin (n = 5, light blue) were significantly lower than Rmax for pyrantel alone (n = 6, red). * p < 0.05, ** p < 0.01 and *** p < 0.001, unpaired two-tailed student t-test. C: Model of ligand sites of action. Pyrantel binds to the orthosteric sites opening the channel. Low concentrations of abamectin (0.03 and 0.1 μM) bind to a negative allosteric site (NAM) in the lipid phase of the channel, inhibiting opening. Higher concentrations of abamectin (0.3, 1 and 10 μM) bind to a positive allosteric site (PAM) increasing opening. D: Abamectin Rmax inhibition (blue curve) and inhibition reduction (red curve) dose response plots. The data points for inhibition used data from 0.03 μM and 0.1 μM abamectin from Fig 3. The data points for inhibition reduction used data from Fig 4B.
Fig 5. Effects of 0.1 μM derquantel alone, 0.3 μM abamectin alone, and derquantel and abamectin combination (0.1 μM derquantel + 0.3 μM abamectin) on the pyrantel concentration-response plots.A: Representative trace (inward currents from oocytes expressing Ode-UNC-29:Ode-UNC-63:Ode-UNC-38) of the 10 seconds application of the control 100 μM acetylcholine, followed by a 10 minutes application of 0.3 μM abamectin and finally, a 10 seconds application of different pyrantel concentrations in the continued presence of abamectin. B: Representative trace (inward currents from oocytes expressing Ode-UNC-29:Ode-UNC-63:Ode-UNC-38) of the 10 seconds application of the control 100 μM acetylcholine, followed by a 10 minutes application of derquantel and abamectin combination and finally, a 10 seconds application of different pyrantel concentrations in the continued presence of the derquantel and abamectin combination. C: Concentration-response plots for pyrantel in the absence (n = 6, red) and presence of 0.1 μM derquantel (n = 4, light purple); 0.3 μM abamectin (n = 5, dark green); 0.1 μM derquantel + 0.3 μM abamectin combination (n = 6, olive green). Results were normalized to 100 μM acetylcholine current responses and expressed as mean ± S.E.M. Inhibition with 0.1 μM derquantel + 0.3 μM abamectin combination was greater than that with 0.1 μM derquantel alone and 0.3 μM abamectin alone. The calculated additive effect for the combination of derquantel and abamectin (broken black) was not statistically different (p > 0.05, paired two-tailed student t-test) from the observed additive effect for the combination of derquantel and abamectin (olive green). D: Bar chart showing the mean ± S.E.M of the maximum current responses (Rmax) for 0.1 μM derquantel (n = 4, light purple); 0.3 μM abamectin (n = 5, dark green); 0.1 μM derquantel + 0.3 μM abamectin combination (n = 6, olive green). Rmax for the combination of 0.1 μM derquantel + 0.3 μM abamectin was significantly smaller than Rmax for 0.1 μM derquantel alone and for 0.3 μM abamectin alone. * p < 0.05 and *** p < 0.001, unpaired two-tailed student t-test.
Beech,
The evolution of pentameric ligand-gated ion-channels and the changing family of anthelmintic drug targets.
2015, Pubmed
Beech,
The evolution of pentameric ligand-gated ion-channels and the changing family of anthelmintic drug targets.
2015,
Pubmed
Blaxter,
A molecular evolutionary framework for the phylum Nematoda.
1998,
Pubmed
Boulin,
Eight genes are required for functional reconstitution of the Caenorhabditis elegans levamisole-sensitive acetylcholine receptor.
2008,
Pubmed
,
Xenbase
Buxton,
Investigation of acetylcholine receptor diversity in a nematode parasite leads to characterization of tribendimidine- and derquantel-sensitive nAChRs.
2014,
Pubmed
,
Xenbase
Greco,
The search for cytotoxic synergy between anticancer agents: a case of Dorothy and the ruby slippers?
1996,
Pubmed
Greenberg,
Ion channels and drug transporters as targets for anthelmintics.
2014,
Pubmed
Guest,
The calcium-activated potassium channel, SLO-1, is required for the action of the novel cyclo-octadepsipeptide anthelmintic, emodepside, in Caenorhabditis elegans.
2007,
Pubmed
Hibbs,
Principles of activation and permeation in an anion-selective Cys-loop receptor.
2011,
Pubmed
Jin,
Near-infrared fluorescence detection of acetylcholine in aqueous solution using a complex of rhodamine 800 and p-sulfonatocalix[8]arene.
2010,
Pubmed
Kotze,
Recent advances in candidate-gene and whole-genome approaches to the discovery of anthelmintic resistance markers and the description of drug/receptor interactions.
2014,
Pubmed
Lacey,
Mode of action of benzimidazoles.
1990,
Pubmed
Leathwick,
Modelling the benefits of a new class of anthelmintic in combination.
2012,
Pubmed
Lee,
Marcfortine and paraherquamide class of anthelmintics: discovery of PNU-141962.
2002,
Pubmed
Lloberas,
Comparative tissue pharmacokinetics and efficacy of moxidectin, abamectin and ivermectin in lambs infected with resistant nematodes: Impact of drug treatments on parasite P-glycoprotein expression.
2013,
Pubmed
Martin,
On the distribution of a fluorescent ivermectin probe (4" 5,7 dimethyl-bodipy proprionylivermectin) in Ascaris membranes.
1992,
Pubmed
Martin,
Emodepside and SL0-1 potassium channels: a review.
2012,
Pubmed
Martin,
Mode of action of levamisole and pyrantel, anthelmintic resistance, E153 and Q57.
2007,
Pubmed
Martin,
Modes of action of anthelmintic drugs.
1997,
Pubmed
Polderman,
Oesophagostomiasis, a common infection of man in northern Togo and Ghana.
1991,
Pubmed
Pullan,
Global numbers of infection and disease burden of soil transmitted helminth infections in 2010.
2014,
Pubmed
Puttachary,
Derquantel and abamectin: effects and interactions on isolated tissues of Ascaris suum.
2013,
Pubmed
Rayes,
The anthelmintic pyrantel acts as a low efficacious agonist and an open-channel blocker of mammalian acetylcholine receptors.
2001,
Pubmed
Robertson,
The action of pyrantel as an agonist and an open channel blocker at acetylcholine receptors in isolated Ascaris suum muscle vesicles.
1994,
Pubmed
Robertson,
Tribendimidine: mode of action and nAChR subtype selectivity in Ascaris and Oesophagostomum.
2015,
Pubmed
Rufener,
Monepantel allosterically activates DEG-3/DES-2 channels of the gastrointestinal nematode Haemonchus contortus.
2010,
Pubmed
,
Xenbase
Saeger,
Latrophilin-like receptor from the parasitic nematode Haemonchus contortus as target for the anthelmintic depsipeptide PF1022A.
2001,
Pubmed
Williamson,
The nicotinic acetylcholine receptors of the parasitic nematode Ascaris suum: formation of two distinct drug targets by varying the relative expression levels of two subunits.
2009,
Pubmed
,
Xenbase
Wolstenholme,
Anthelmintics - from discovery to resistance.
2014,
Pubmed
Wolstenholme,
Glutamate-gated chloride channels and the mode of action of the avermectin/milbemycin anthelmintics.
2005,
Pubmed
Wolstenholme,
Ion channels and receptor as targets for the control of parasitic nematodes.
2011,
Pubmed
