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The Conqueror Worm: recent advances with cholinergic anthelmintics and techniques excite research for better therapeutic drugs.

Martin RJ, Puttachary S, Buxton SK, Verma S, Robertson AP - J. Helminthol. (2014)

Bottom Line: Here we illustrate the use of three parasite nematode models, Ascaris suum, Oesophagostomum dentatum and Brugia malayi, microfluidic techniques and the Xenopus oocyte expression system for testing and examining the effects of cholinergic anthelmintics.We also show how the combination of derquantel, the selective nematode cholinergic antagonist and abamectin produce increased inhibition of the nicotinic acetylcholine receptors on the nematode body muscle.We are optimistic that new compounds and combinations of compounds can limit the effects of drug resistance, allowing anthelmintics to be continued to be used for effective treatment of human and animal helminth parasites.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Sciences,College of Veterinary Medicine, Iowa State University,USA.

ABSTRACT
The following account is based on a review lecture given recently at the British Society of Parasitology. We point out that nematode parasites cause very widespread infections of humans, particularly in economically underdeveloped areas where sanitation and hygiene are not adequate. In the absence of adequate clean water and effective vaccines, control and prophylaxis relies on anthelmintic drugs. Widespread use of anthelmintics to control nematode parasites of animals has given rise to the development of resistance and so there is a concern that similar problems will occur in humans if mass drug administration is continued. Recent research on the cholinergic anthelmintic drugs has renewed enthusiasm for the further development of cholinergic anthelmintics. Here we illustrate the use of three parasite nematode models, Ascaris suum, Oesophagostomum dentatum and Brugia malayi, microfluidic techniques and the Xenopus oocyte expression system for testing and examining the effects of cholinergic anthelmintics. We also show how the combination of derquantel, the selective nematode cholinergic antagonist and abamectin produce increased inhibition of the nicotinic acetylcholine receptors on the nematode body muscle. We are optimistic that new compounds and combinations of compounds can limit the effects of drug resistance, allowing anthelmintics to be continued to be used for effective treatment of human and animal helminth parasites.

No MeSH data available.


Related in: MedlinePlus

(colour online) Nomarski photomicrograph of a Brugia malayi muscle flap dissection with a diagram of a patch-pipette placed for whole-cell current clamp recording of the nicotinic receptors. Scale bar 10 μm. (B) Bar chart (mean ± SE) of normalized currents produced by the nAChR agonists/anthelmintics (30 μM) on B. malayi muscles in whole-cell patch-clamp. All current responses were normalized to ACh currents (*P < 0.05, paired t-test). Displayed above the bars are sample whole-cell current traces. Scale bar, horizontal 30 s, vertical 700 pA. (C) Plot of motility versus time (min) of adult female B. malayi in the absence and presence of 30 μM levamisole. Four worms/treatment were used for the assay. Comparisons of motility were made between control and treated worms at each time point, **P < 0.01, ***P < 0.001.
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Figure 7: (colour online) Nomarski photomicrograph of a Brugia malayi muscle flap dissection with a diagram of a patch-pipette placed for whole-cell current clamp recording of the nicotinic receptors. Scale bar 10 μm. (B) Bar chart (mean ± SE) of normalized currents produced by the nAChR agonists/anthelmintics (30 μM) on B. malayi muscles in whole-cell patch-clamp. All current responses were normalized to ACh currents (*P < 0.05, paired t-test). Displayed above the bars are sample whole-cell current traces. Scale bar, horizontal 30 s, vertical 700 pA. (C) Plot of motility versus time (min) of adult female B. malayi in the absence and presence of 30 μM levamisole. Four worms/treatment were used for the assay. Comparisons of motility were made between control and treated worms at each time point, **P < 0.01, ***P < 0.001.

Mentions: We are particularly excited by developments of the B. malayi muscle-flap preparation for recording from single muscle cells (Robertson et al., 2011, 2013). We glue one side of a 0.5 cm body cylinder section with GluShield (®Glushield, Seattle, Washington, USA) delivered with a modified patch pipette under the high power of the dissecting microscope. The body cylinder is then cut open and, after removal of the intestine and uterus, it is glued flat. We use Nomarski optics (fig. 7) to view the muscle cells. We make patch recordings following brief collagenase treatment to clear the extracellular matrix. Single-channel recordings using cell-attached and isolated inside-out patch recordings or whole-cell recordings allow us to study nAChRs in the intact preparation. Figure 7B shows our recently developed recording system for whole-cell currents made from a B. malayi muscle (Robertson et al., 2011, 2013). It shows the sequential application of 30 μM acetylcholine, tribendimidine, pyrantel, levamisole and bephenium along with a bar chart of normalized currents. Interestingly bephenium is the least potent of the agonist series, which is different from the situation in A. suum muscle, suggesting that the receptor subtypes present are different from the receptors of B. malayi.Figure 7C shows the effect of longer-term application of 30 μM levamisole on adult motility, and that after a period of some 10 min the inhibition of motility begins to be lost.


The Conqueror Worm: recent advances with cholinergic anthelmintics and techniques excite research for better therapeutic drugs.

Martin RJ, Puttachary S, Buxton SK, Verma S, Robertson AP - J. Helminthol. (2014)

(colour online) Nomarski photomicrograph of a Brugia malayi muscle flap dissection with a diagram of a patch-pipette placed for whole-cell current clamp recording of the nicotinic receptors. Scale bar 10 μm. (B) Bar chart (mean ± SE) of normalized currents produced by the nAChR agonists/anthelmintics (30 μM) on B. malayi muscles in whole-cell patch-clamp. All current responses were normalized to ACh currents (*P < 0.05, paired t-test). Displayed above the bars are sample whole-cell current traces. Scale bar, horizontal 30 s, vertical 700 pA. (C) Plot of motility versus time (min) of adult female B. malayi in the absence and presence of 30 μM levamisole. Four worms/treatment were used for the assay. Comparisons of motility were made between control and treated worms at each time point, **P < 0.01, ***P < 0.001.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4247809&req=5

Figure 7: (colour online) Nomarski photomicrograph of a Brugia malayi muscle flap dissection with a diagram of a patch-pipette placed for whole-cell current clamp recording of the nicotinic receptors. Scale bar 10 μm. (B) Bar chart (mean ± SE) of normalized currents produced by the nAChR agonists/anthelmintics (30 μM) on B. malayi muscles in whole-cell patch-clamp. All current responses were normalized to ACh currents (*P < 0.05, paired t-test). Displayed above the bars are sample whole-cell current traces. Scale bar, horizontal 30 s, vertical 700 pA. (C) Plot of motility versus time (min) of adult female B. malayi in the absence and presence of 30 μM levamisole. Four worms/treatment were used for the assay. Comparisons of motility were made between control and treated worms at each time point, **P < 0.01, ***P < 0.001.
Mentions: We are particularly excited by developments of the B. malayi muscle-flap preparation for recording from single muscle cells (Robertson et al., 2011, 2013). We glue one side of a 0.5 cm body cylinder section with GluShield (®Glushield, Seattle, Washington, USA) delivered with a modified patch pipette under the high power of the dissecting microscope. The body cylinder is then cut open and, after removal of the intestine and uterus, it is glued flat. We use Nomarski optics (fig. 7) to view the muscle cells. We make patch recordings following brief collagenase treatment to clear the extracellular matrix. Single-channel recordings using cell-attached and isolated inside-out patch recordings or whole-cell recordings allow us to study nAChRs in the intact preparation. Figure 7B shows our recently developed recording system for whole-cell currents made from a B. malayi muscle (Robertson et al., 2011, 2013). It shows the sequential application of 30 μM acetylcholine, tribendimidine, pyrantel, levamisole and bephenium along with a bar chart of normalized currents. Interestingly bephenium is the least potent of the agonist series, which is different from the situation in A. suum muscle, suggesting that the receptor subtypes present are different from the receptors of B. malayi.Figure 7C shows the effect of longer-term application of 30 μM levamisole on adult motility, and that after a period of some 10 min the inhibition of motility begins to be lost.

Bottom Line: Here we illustrate the use of three parasite nematode models, Ascaris suum, Oesophagostomum dentatum and Brugia malayi, microfluidic techniques and the Xenopus oocyte expression system for testing and examining the effects of cholinergic anthelmintics.We also show how the combination of derquantel, the selective nematode cholinergic antagonist and abamectin produce increased inhibition of the nicotinic acetylcholine receptors on the nematode body muscle.We are optimistic that new compounds and combinations of compounds can limit the effects of drug resistance, allowing anthelmintics to be continued to be used for effective treatment of human and animal helminth parasites.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Sciences,College of Veterinary Medicine, Iowa State University,USA.

ABSTRACT
The following account is based on a review lecture given recently at the British Society of Parasitology. We point out that nematode parasites cause very widespread infections of humans, particularly in economically underdeveloped areas where sanitation and hygiene are not adequate. In the absence of adequate clean water and effective vaccines, control and prophylaxis relies on anthelmintic drugs. Widespread use of anthelmintics to control nematode parasites of animals has given rise to the development of resistance and so there is a concern that similar problems will occur in humans if mass drug administration is continued. Recent research on the cholinergic anthelmintic drugs has renewed enthusiasm for the further development of cholinergic anthelmintics. Here we illustrate the use of three parasite nematode models, Ascaris suum, Oesophagostomum dentatum and Brugia malayi, microfluidic techniques and the Xenopus oocyte expression system for testing and examining the effects of cholinergic anthelmintics. We also show how the combination of derquantel, the selective nematode cholinergic antagonist and abamectin produce increased inhibition of the nicotinic acetylcholine receptors on the nematode body muscle. We are optimistic that new compounds and combinations of compounds can limit the effects of drug resistance, allowing anthelmintics to be continued to be used for effective treatment of human and animal helminth parasites.

No MeSH data available.


Related in: MedlinePlus