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Partial characterization of specific cantharidin binding sites in mouse tissues
M J Graziano1, I N Pessah, M Matsuzawa
1Department of Entomological Sciences, University of California, Berkeley 94720.
Molecular Pharmacology
|June 1, 1988
Summary
Cantharidin toxicity in mice is linked to specific binding in liver cytosol. This binding site
Area of Science:
- Biochemistry
- Toxicology
- Pharmacology
Background:
- Cantharidin, a vesicant from blister beetles, has known toxicity.
- Its precise molecular mechanism of action remains incompletely understood.
Purpose of the Study:
- To investigate the molecular interactions of cantharidin using radioligand binding assays.
- To identify and characterize the specific binding sites of cantharidin in mouse tissues.
- To establish the toxicological relevance of these binding sites.
Main Methods:
- Radioligand binding studies using [3H]cantharidin with mouse liver cytosol.
- Characterization of binding kinetics, including Kd, Bmax, pH optimum, and inhibitor sensitivity.
- Correlation of analog binding affinity with acute toxicity data.
- Dose-dependent inhibition studies in poisoned mice.
Main Results:
- Specific, saturable binding of [3H]cantharidin observed in mouse liver cytosol.
- Binding site characterized by specific kinetic parameters and sensitivity to divalent cations and nucleotide triphosphates.
- High correlation (r = 0.829) between analog potency in inhibiting binding and acute toxicity.
- Similar binding characteristics found in mouse brain cytosol.
Conclusions:
- Cantharidin toxicity is attributable to its specific binding to a site in mouse liver cytosol.
- This binding site and its characteristics are conserved in other tissues like the brain.
- The findings provide a molecular basis for the toxicity of cantharidin and related oxabicycloheptanes.