Species differences in the tissue distribution of catechol and methylsulphonyl metabolites of 2,4,5,2',5'-penta- and 2,3,4,2',3',6'-hexachlorobiphenyls in rats, mice, hamsters and guinea pigs

Abstract

Polychlorinated biphenyls (PCBs) are metabolized to phenolic or methylsulphonyl PCBs (MeSO₂-CBs) in animal species. The study determined the species differences in the tissue distribution of persistent PCB metabolites in rats, mice, hamsters and guinea pigs 4 days after exposure to 2,4,5,2',5'-pentachlorobiphenyl (CB101) or 2,3,4,2',3',6'-hexachlorobiphenyl (CB132). For CB101 metabolism, the hydroxylation in rats, mice and hamsters occurred primarily at the 3'-position in the 2',5'-dichlorinated phenyl ring, whereas the hydroxylation in guinea pigs occurred preferentially at the 3-position. Metabolite profiles in tissues of hamsters were dominated by 3',4'-catechol-CB101, whereas metabolite profiles in rats and mice were dominated by 3'- or 4'-MeSO₂-CBs. For CB132 metabolism, rats and mice produced 4'- and 5'-MeSO₂-CBs at similar concentration ratios, whereas guinea pigs produced MeSO₂-CBs at higher levels and selectively retained 5'-MeSO₂-CB in liver. In contrast, hamsters preferentially produced 4',5'-catechol-CB132 that was retained in serum. Consequently, hamsters produced catechols, whereas guinea pigs produced meta-substituted MeSO₂-CBs, preferentially from CB132. These findings indicate that PCBs with 2,3,6-chlorine substitution are preferred substrates for the formation of catechols or MeSO₂-CBs and the differences in metabolite profiles are related to species-dependent metabolic capacities.

Key words::

• Species difference
• tissue distribution
• methylsulphonyl
• catechol
• polychlorinated biphenyl