Comparison of Ivermectin-Induced Paralysis of the Pharyngeal and Somatic Musculature of Ivermectin-Sensitive and -Resistant Strains of a Parasitic Nematode,Haemonchus Contortus
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Authors
Hernández, Caterina Maria
Issue Date
1996
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Nematodes that parasitize the mammalian gastrointestinal
tract are a serious health problem in human and veterinary medicine.
The use of drugs, called anthelmintics, to control these infectious
organisms is most developed for ruminant animals. Currently, the
primary class of anthelmintics used to treat ruminant nematodiases
is termed the macrocyclic lactones, typified by Ivermectin.
Unfortunately, as is the case for essentially all chemotherapeutic
agents, resistance to Ivermectin has appeared in the field. In order
to investigate this example of drug resistance, I focused my studies
on a trichostrongylid parasite of ruminants, Haemonchus contortus,
which is a large parasite and easily obtainable for laboratory use.
The basis for Ivermectin resistance in H. contortus, as for other
parasitic nematodes, is undefined. Ivermectin paralyzes both the
somatic and pharyngeal muscular systems in nematodes, inhibiting
movement and preventing oral ingestion of nutrients. These effects
seem to be mediated through different receptors. To determine if
either is more affected in resistant strains, this study compared the
differential effects of Ivermectin on motility and pharyngeal
function in Ivermectin-sensitive and -resistant strains of H.
contortus. Using a radiometric assay to measure oral ingestion in
adult parasites and an automated motility recorder to measure body
wall paralysis, it was found that both parameters were less
sensitive to the drug in the Ivermectin-resistant strain compared to
the sensitive strain. Based on these results, it does not appear that
Ivermectin resistance is mediated by the mutation of a tissue-specific
receptor.
Description
vii, 48 p.
Citation
Publisher
Kalamazoo College
License
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