QUANTITATIVE STRUCTURE-ACTIVITY-RELATIONSHIPS - ANALYSIS OF INTERACTIONS OF 2,3,7,8-TETRACHLORODIBENZO-PARA-DIOXIN AND 2-SUBSTITUTED ANALOGS WITH RAT, MOUSE, GUINEA-PIG, AND HAMSTER CYTOSOLIC RECEPTOR | Academic Article individual record
abstract

The competitive receptor binding affinities of thirteen 2-substituted 3,7,8-trichlorodibenzo-p-dioxins to hepatic cytosol from rat, mouse, guinea pig, and hamster were determined with [3H]-2,3,7,8-tetrachlorodibenzo-p-dioxin as the radioligand. Multiple parameter linear regression analysis of the binding data from the four species gave the following equations: pEC50 (rat) = 7.196 + 0.600 pi - 0.255 delta Es - 1.683 HB pEC50 (mouse) = 6.365 + 1.641 pi + 1.206 sigma 0 pEC50 (hamster) = 7.416 + 1.026 pi + 0.509 delta Es + 0.748 sigma 0 pEC50 (guinea pig) = 6.892 + 1.035 pi where pi, delta Es, HB, sigma 0, and Vw are physicochemical parameters for substituent lipophilicity, steric effect, hydrogen bonding capacity, electronegativity, and van der Waals volume (relative to H), respectively. These equations demonstrate that there are important species differences in the receptor protein binding site interactions with the substituted analogues. These data, coupled with the known species differences in the molecular properties of the receptor proteins, are evidence for a heterologous nature of the receptor between mammalian species. Multiple parameter linear regression analysis of the relative aryl hydrocarbon hydroxylase (AHH) induction potencies of these analogues in rat hepatoma H-4-II E-cells in culture gave the following equation. The correlation pEC50 (AHH induction) = 3.208 + 0.950 pEC50 (rat binding) - 0.955 delta B5 between receptor binding and AHH induction was dependent on a steric parameter (delta B5, STERIMOL) and the results suggest that an additional substituent-dependent process (e.g., an activation step) may be required after initial ligand-receptor binding for the ultimate expression of the receptor-mediated response (i.e., AHH induction).

authors
author list (cited authors)
ROMKES, M., PISKORSKAPLISZCZYNSKA, J., KEYS, B., SAFE, S., & FUJITA, T.
publication date
1987
published in
keywords
  • Liver
  • Receptors, Aryl Hydrocarbon
  • Mice, Inbred C57BL
  • Cricetinae
  • Dioxins
  • Tetrachlorodibenzodioxin
  • Species Specificity
  • Polychlorinated Dibenzodioxins
  • Rats
  • Receptors, Drug
  • Regression Analysis
  • Animals
  • Mice
  • Guinea Pigs
  • Mesocricetus
  • Cytosol
  • Structure-Activity Relationship
  • Aryl Hydrocarbon Hydroxylases
  • Rats, Inbred Strains