Induction of Cytochrome P450 Isoenzymes after Toxicokinetic Interactions between 2,3,7,8-Tetrachlorodibenzo-p-dioxin and 2,2′,4,4′,5,5′-Hexachlorobiphenyl in the Liver of the Mouse

Opposite Effects of 2,2′,4,4′,5,5′-Hexachlorobiphenyl and 2,3,7,8-Tetrachlorodibenzo-p-dioxin on the Antibody Response to Sheep Erythrocytes in Mice

“…In contrast, all doses of TCDD combined with the high dose of PCB153 resulted in a dose-related increase in hepatic weight. This interactive effect of TCDD and PCB153 on increased liver weight has been observed by others (DeJongh et al, 1995).…”

“…Mice were weighed and dosed with TCDD alone (i.e., 0, 0.1, 1.0, or 10 /ig/kg body wt), PCB153 alone (i.e., 0, 3.58, 35.8, or 358 mg/kg body wt), and all possible combinations, as a single oral dose in a volume of 10 ml/kg. The doses of PCB 153 used in this study were chosen based on the fact that these doses have been reported to alter TCDD-induced responses (Bannister et al, 1987;Biegel et al, 1989;Morrissey et ai, 1992;DeJongh et al, 1995). It was impossible to perform a single multimatrix experiment that included all TCDD and PCB 153 doses alone as well as TCDD and PCB 153 dose combinations.…”

Inhibition of 3,3′,4,4′,5-Pentachlorobiphenyl-Induced Chicken Embryotoxicity by 2,2′,4,4′,5,5′-Hexachlorobiphenyl

“…These results suggest that the antagonism observed for 2,2',4,4',5,5'-hexaCB may occur by mechanisms other than through the Ah receptor (Davis and Safe, 1990). A recent study by De Jongh et al (1995) has shown that the concentration of TCDD in the liver (% dose/ g tissue) was increased in the animals cotreated with TCDD and 2,2',4,4',5,5'-hexaCB compared to the animals treated with TCDD alone. The increase in the hepatic retention and subsequent decrease in available TCDD reaching the palate may contribute to the antagonistic action of 2,2',4,4',5,5'-hexaCB.…”

Toxic Equivalency Factors (TEFs) for PCBs, PCDDs, PCDFs for Humans and Wildlife

“…However, in rainbow trout at greater doses, the same mixture was found less than additive (213). In addition, PCB 153 had an antagonistic effect on the induction of EROD activity by TCDD (214), but was found to be synergistic in another study (215).…”