Trichostrongylus colubriformis: Effect of anthelmintics on ingestion and oviposition

Bottjer, Kurt P.; Bone, Leon W.

doi:10.1016/0020-7519(85)90044-x

Cited by 19 publications

(7 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We speculate that the molecular and cellular pathways for pumping inhibition identified here are shared with the pathways involved in the function of ivermectin, which is known to inhibit nematode pumping [39,40]. First, the avr-15 and avr-14 glutamate-gated chloride channels that we have found to function in light-induced inhibition of pumping also function in ivermectin-induced inhibition of pumping [14].…”

Section: Discussionmentioning

confidence: 87%

Distinct Neural Circuits Control Rhythm Inhibition and Spitting by the Myogenic Pharynx of C. elegans

et al. 2015

View full text Add to dashboard Cite

SUMMARY Neural circuits have long been known to modulate myogenic muscles such as the heart, yet a mechanistic understanding at the cellular and molecular levels remains limited. We studied how light inhibits pumping of the Caenorhabditis elegans pharynx, a myogenic muscular pump for feeding, and found three neural circuits that alter pumping. First, light inhibits pumping via the I2 neuron monosynaptic circuit. Our electron microscopic reconstruction of the anterior pharynx revealed evidence for synapses from I2 onto muscle that were missing from the published connectome, and we show that these "missed synapses" are likely functional. Second, light inhibits pumping through the RIP-I1-MC neuron polysynaptic circuit, in which an inhibitory signal is likely transmitted from outside the pharynx into the pharynx in a manner analogous to how the mammalian autonomic nervous system controls the heart. Third, light causes a novel pharyngeal behavior, reversal of flow or "spitting," which is induced by the M1 neuron. These three neural circuits show that neurons can control a myogenic muscle organ not only by changing the contraction rate but also by altering the functional consequences of the contraction itself, transforming swallowing into spitting. Our observations also illustrate why connectome builders and users should be cognizant that functional synaptic connections might exist despite the absence of a declared synapse in the connectome.

show abstract

Section: Discussionmentioning

confidence: 87%

Distinct Neural Circuits Control Rhythm Inhibition and Spitting by the Myogenic Pharynx of C. elegans

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Pharyngeal pumping in nematodes is extremely sensitive to the A/M, and in many species the pharynx is the most sensitive organ to the effects of the drugs, with reported EC50 values of 0 . 2 to 10 nM (Bottjer & Bone, 1985 ;Avery & Horvitz, 1990 ;Geary et al 1993 ;Gill et al 1995 ;Paiement et al 1999 ;Sheriff et al 2002). This may mean that the primary anthelmintic effect of the A/M is on the pharynx and that its paralysis leads to worm death, either due to starvation or to the loss of internal turgor pressure.…”

Section: P-g L Y C O P R O T E I N S a N D T H E A / M A N T H E L M mentioning

confidence: 99%

Glutamate-gated chloride channels and the mode of action of the avermectin/milbemycin anthelmintics

2006

View full text Add to dashboard Cite

The macrocyclic lactones are the biggest selling and arguably most effective anthelmintics currently available. They are good substrates for the P-glycoproteins, which might explain their selective toxicity for parasites over their vertebrate hosts. Changes in the expression of these pumps have been implicated in resistance to the macrocyclic lactones, but it is clear that they exert their anthelmintic effects by binding to glutamate-gated chloride channels expressed on nematode neurones and pharyngeal muscle cells. This effect is quite distinct from the channel opening induced by glutamate, the endogenous transmitter acting at these receptors, which produces rapidly opening and desensitising channels. Ivermectin-activated channels open very slowly but essentially irreversibly, leading to a very long-lasting hyperpolarisation or depolarisation of the neurone or muscle cell and therefore blocking further function. Molecular and genetic studies have shown that there are multiple GluCl isoforms in both free-living and parasitic nematodes: the exact genetic make-up and functions of the GluCl may vary between species. The known expression patterns of the GluCl explain most of the observed biological effects of treatment with the macrocyclic lactones, though the reason for the long-lasting inhibition of larval production in filarial species is still poorly understood.

show abstract

“…Its morphology, especially the anterior part with the pharynx, serves as a taxonomically relevant criterion (Chitwood and Chitwood 1950;Lorenzen 1983), and it is the most important feeding organ in nearly all adult rhabditid worms and many larval stages (Bottjer and Bone 1985;Geary et al 1993). Our comparative ®ne-structure study showed that the selection of compounds caused dierent alterations in adult Onchocerca volvulus tissues and organs.…”

Section: Discussionmentioning

confidence: 99%

The anterior central nervous system of male Onchocerca volvulus (Nematoda: Filarioidea) as a target for chemotherapy: results of an electron microscopy study

Strote

Bonow

Attah³

1997

Parasitol Res

View full text Add to dashboard Cite

An electron microscopy study was performed to evaluate the feasibility of the use of the anterior nerve ring of male Onchocerca volvulus for the assessment of early drug effects. Worms were exposed to new and known compounds at reasonable concentrations of 1 microM and less for 6, 12, 18, and 36 h in an established in vitro system. The anterior end of the filariae up to a length of 1 mm was examined and the morphological findings were compared with motility and reduction of a tetrazolium sat to formazan by live but not dead worms. The nerve fibers were more susceptible to the chemotherapeutic intervention then the other tissues in the anteriormost part of the worms. The alterations depended on the duration of exposure and the chemical nature of the compounds used. Morphological changes in the nervous tissue and the inhibition of motility and formazan production corresponded well for the arsenical mel w, used as an active standard, two pyrimidinyl-guanidines (PD 105482 and PD 105666), and an imidazolinylhydrazone (WR 251993).

show abstract

Trichostrongylus colubriformis: Effect of anthelmintics on ingestion and oviposition

Cited by 19 publications

References 9 publications

Distinct Neural Circuits Control Rhythm Inhibition and Spitting by the Myogenic Pharynx of C. elegans

Distinct Neural Circuits Control Rhythm Inhibition and Spitting by the Myogenic Pharynx of C. elegans

Glutamate-gated chloride channels and the mode of action of the avermectin/milbemycin anthelmintics

The anterior central nervous system of male Onchocerca volvulus (Nematoda: Filarioidea) as a target for chemotherapy: results of an electron microscopy study

Contact Info

Product

Resources

About