title: Increased resistance to anthelmintics of Haemonchus contortus eggs associated with changes in membrane fluidity of eggshells during embryonation.
abstract: The embryonation of nematode eggs has been shown to increase their resistance to anthelmintics when parasites are submitted to egg hatch assays. Nevertheless, no mechanism has been suggested to explain this phenomenon. Earlier observations by other authors showed that the biochemical composition of eggshells is altered during the embryonation of eggs. The functional consequences of these changes have not been identified. We studied the changes in membrane environment (eggshells) of Haemonchus contortus eggs during the embryonation by fluidity measurements and their effects on nonspecific mechanisms of resistance to anthelmintics. We previously demonstrated that these mechanisms imply P-glycoproteins (Pgp) belonging to the multi-drug resistance (MDR) system and that the Pgp activity is very susceptible to their lipidic environment. The results obtained here show that the embryonation induced a significant and gradual increase in eggshell fluidity which was associated with an increased resistance to anthelmintics. Differences were observed between H. contortus isolates with various levels of resistance which might result from their specific biology and/or membrane composition. The membrane environment changes could act both on the solubilization of anthelmintics into the eggs and on the efflux of these lipophilic molecules by Pgp.
authors.affiliation: MultiResistances et Antiparasitic drugs, INRA-Tours: UR086-BioAgressors, Health and Environment, 37380 , Nouzilly, France.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Riou
authors.forename: Christine
authors.initials: C
authors.lastname: Koch
authors.forename: Dominique
authors.initials: D
authors.lastname: Kerboeuf
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology*; D004351:Drug Resistance; D005454:Fluorescence Polarization; D006189:Haemonchus / Q000187:drug effects* / Q000196:embryology / Q000502:physiology; D008560:Membrane Fluidity; D010063:Ovum / Q000187:drug effects / Q000502:physiology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000969:Antinematodal Agents