Maternal hepatic and embryonic effects of 1,2,3,4-tetrachlorobenzene in the rat.
To assess possible maternal hepatic and reproductive effects of this uncharged, low molecular weight, lipophilic chlorinated benzene 0, 100, 300 and 1000 mg/kg/day of 1,2,3,4-tetrachlorobenzene (TCB) was orally administered to pregnant rats on days 9-13 of gestation and the animals were killed on day 14 of pregnancy. Phenobarbital and beta-naphthoflavone were administered to other pregnant rats as positive hepatic controls. Maternal mortality (7/19 rats) was increased and body weight gain was greatly decreased in the 1000 mg/kg/day TCB group. Liver to body weight ratio and hepatic microsomal protein content were unaffected by any TCB treatment. On day 14 maternal NADPH-cytochrome c reductase activity was increased at 1000 mg/kg/day, while the maternal hepatic microsomal cytochrome P-450 content was significantly induced by both 300 and 1000 mg/kg/day of TCB. Microsomal N-demethylation of aminopyrine was increased from 2.6 to 4.0 and 4.5 nmol/mg protein/min at doses of 300 and 1000 mg/kg TCB, respectively. However, maternal hepatic microsomal ethoxyresorufin O-deethylase activity was not consistently increased by TCB. Hepatic glutathione S-transferase activity towards 1,2-dichloro-4-nitrobenzene was increased only by the 1000 mg/kg/day TCB treatment. The rate of microsomal p-nitrophenol and phenolphthalein glucuronidation was increased by TCB administration. Embryonic growth was adversely affected by TCB treatment. Yolk sac diameter, embryonic crown-rump length, and head length were all decreased by treatment with 300 mg/kg/day TCB. This TCB treatment did not significantly elevate the number of dead or abnormal embryos.
D000821:Animal Feed; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002722:Chlorobenzenes / Q000008:administration & dosage / Q000633:toxicity*; D004622:Embryo, Mammalian / Q000187:drug effects*; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D008099:Liver / Q000187:drug effects*; D008431:Maternal-Fetal Exchange; D008862:Microsomes, Liver / Q000201:enzymology; D009929:Organ Size / Q000187:drug effects; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains / Q000196:embryology / Q000254:growth & development
D002722:Chlorobenzenes; C030386:1,2,3,4-tetrachlorobenzene