PubMed Health⌕ Search

Biomedical subjects

C Legraverend

Publications and source records attributed to C Legraverend.

28 records · Page 2Linked to original sources
PubMed1984

Importance of the route of administration for genetic differences in benzo[a]pyrene-induced in utero toxicity and teratogenicity.

C57BL/6N (Ahb/Ahb) mice have a high-affinity Ah receptor in tissues, whereas AKR/J and DBA/2N (Ahd/Ahd) mice have a poor-affinity Ah receptor. The cytochrome P1-450 induction response (enhanced benzo[a]pyrene metabolism) occurs much more readily in Ahb/Ahb and Ahb/Ahd than in Ahd/Ahd mice, at any given dose of the inducer benzo[a]pyrene. Embryos from the AKR/J X (C57BL/6N)(AKR/J)F1 and the reciprocal backcross were studied during benzo[a]pyrene feeding of the pregnant females. Oral benzo[a]pyrene (120 mg/kg/day) given to pregnant Ahd/Ahd mice between gestational day 2 and 10 produces more intrauterine toxicity and malformations in Ahd/Ahd than Ahb/Ahd embryos. This striking allelic difference is not seen in pregnant Ahb/Ahd mice receiving oral benzo[a]pyrene. Pharmacokinetics studies with [3H]benzo[a]pyrene in the diet and high-performance liquid chromatographic analysis of benzo[a]pyrene metabolism in vitro by the maternal intestine, liver, and ovary and the embryos of control and oral benzo[a]pyrene-treated pregnant females are consistent with "first-pass elimination" kinetics and differences in benzo[a]pyrene metabolism by the embryos and/or placentas versus maternal tissues. In the pregnant Ahd/Ahd mouse receiving oral benzo[a]pyrene, little induction of benzo[a]pyrene metabolism occurs in her intestine and liver; this leads to much larger amounts of benzo[a]pyrene reaching her embryos, and genetic differences in toxicity and teratogenesis are manifest. In the pregnant Ahb/Ahd mouse receiving oral benzo[a]pyrene, benzo[a]pyrene metabolism is greatly enhanced in her intestine and liver; this leads to less benzo[a]pyrene reaching her embryos, much less intrauterine toxicity and malformations, and no genetic differences are manifest. More toxic metabolites (especially benzo[a]pyrene 1,6- and 3,6-quinones) are shown to occur in Ahd/Ahd embryos than in Ahb/Ahd embryos. In additional studies, no prenatal or neonatal "imprinting" effect in C57BL/6N mice by 2,3,7,8-tetrachlorodibenzo-p-dioxin or Aroclor 1254 on benzo[a]pyrene metabolism later in life was detectable. These genetic differences in intrauterine toxicity and teratogenicity induced by oral benzo[a]pyrene are just opposite those induced by intraperitoneal benzo[a]pyrene [Shum et al., '79; Hoshino et al., '81). The data in the present report emphasize the importance of the route of administration when the teratogen induces its own metabolism.

Abnormalities, Drug-Induced↗
PubMed1984

Aryl hydrocarbon hydroxylase induction by benzo[a]anthracene: regulatory gene localized to the distal portion of mouse chromosome 17.

Aryl hydrocarbon (benzo[a]pyrene) hydroxylase inducibility by benzo[a]anthracene was studied in 29 somatic cell hybrid clones, developed by fusing mouse spleen or peritoneal cells from four different inbred strains with hypoxanthine phosphoribosyltransferase-deficient Chinese hamster E36 cells. Karyotype analysis plus 25 markers assigned to 16 autosomes and the X chromosome were examined. In 28 of the 29 clones, the presence or absence of inducibility is associated with the presence or absence, respectively, of mouse chromosome 17. Liver microsomal aryl hydrocarbon hydroxylase induction by 3-methylcholanthrene or benzo[a]anthracene was assessed in appropriate backcrosses with the Mus musculus molossinus, M. m. castaneus, MOR/Cv, PL/J, SM/J and DBA/2J inbred strains and in 13 NX8 recombinant inbred lines. Twenty-seven biochemical genetic markers representing all but four autosomes were tested for possible linkage with the hydroxylase inducibility, and no linkage was found. The hepatic Ah receptor was quantitated in 26 BXD recombinant inbred lines; the Ah phenotype did not match exactly any of the more than 70 genes with established strain distribution patterns representing 12 autosomes and at least five unlinked markers. It is concluded that a major gene controlling aryl hydrocarbon hydroxylase inducibility by benzo[a]anthracene is located on chromosome 17. Because there is no significant linkage with any of three biochemical markers in the upper third of the chromosome, we conclude that the inducibility gene is located in the distal 40% of mouse chromosome 17. Whether this trait represents the Ah locus, i.e., the gene encoding the cytosolic Ah receptor, will require further study.

Animals↗
PubMed1983

Bone marrow toxicity induced by oral benzo[a]pyrene: protection resides at the level of the intestine and liver.

The Ah locus encodes a cytosolic receptor that regulates the induction of certain drug-metabolizing enzymes by polycyclic aromatic hydrocarbons such as benzo[a]pyrene. Some inbred mouse strains such as C57BL/6N have the high-affinity Ah receptor (Ahb/Ahb), others such as DBA/2N, the poor-affinity receptor (Ahd/Ahd). Presence of the high-affinity receptor leads to greater cytochrome P1-450 induction by benzo[a]pyrene; in turn, enhanced benzo[a]pyrene metabolism can result in more toxic intermediates or greater detoxication, depending upon the test system studied. Benzo[a]pyrene in the growth medium, in direct contact with cultured myeloid cells, is more toxic to C57BL/6N than DBA/2N cultured cells. Oral benzo[a]pyrene induces P1-450 (measured by benzo[a]pyrene trans-7,8-dihydrodiol formation determined by high-performance liquid chromatography) in C57BL/6N but not DBA/2N intestine and liver. In the bone marrow of oral benzo[a]pyrene-treated C57BL/6N and DBA/2N mice, the magnitude of P1-450 induction is about the same. WB/ReJ (Ahd/Ahd), C57BL/6J (Ahb/Ahb), or (WB/ReJ)(C57BL/6J)F1 (Ahb/Ahd) marrow was transplanted into lethally irradiated (WB/ReJ)(C57BL/6J)F1 mice. DBA/2J (Ahd/Ahd) marrow was transplanted into lethally irradiated BALB/cByJ (Ahb/Ahb) mice and vice versa. Mice having the Ahd/Ahd intestine and liver died in less than 3 weeks of benzo[a]pyrene feeding (120 mg/kg/day), irrespective of the source of transfused marrow. All the data are consistent with pharmacokinetic differences in the tissue distribution of benzo[a]pyrene: mice having the high-affinity receptor, and therefore the P1-450 induction process in the intestine and liver, are protected from oral benzo[a]pyrene-induced myelotoxicity.

Administration, Oral↗
PubMed1980

DNA binding of benzo[a]pyrene metabolites. Effects of substrate and microsomal protein concentration in vitro, dietary contaminants, and tissue differences.

The binding of reactive benzo[a]pyrene metabolites to deproteinized DNA in vitro can be drastically changed, both quantitatively and qualitatively, in vitro by changes in the substrate concentration or the substrate/P-450 ratio, and in the intact animal by starvation or substitution of a 'purified protein test diet' for the regular laboratory chow. Liver, lung, and bowel microsomes from C57BL/6N and DBA/2N mice were examined. These data demonstrate the importance of dietary contaminants or nutrition during benzo[a]pyrene tumorigenesis. The profile of DNA binding of benzo[a]pyrene metabolites is also shown to be an extremely sensitive test for detecting minute amounts of induced cytochrome P1-450 and its associated aryl hydrocarbon (benzo[a]pyrene) hydroxylase (EC 1.14.14.2) activity. A direct correlation is not necessarily observed, however, between 'aryl hydrocarbon hydroxylase activity' and the amount of benzo[a]pyrene metabolites bound covalently to DNA. 'Untreated' genetically responsive mice are shown to have greater 'control' levels of benzo[a]pyrene metabolism in their various tissues than genetically nonresponsive mice simply on the basis that responsive mice have a lower threshold for 'responsiveness' to exogenous inducers inhaled and/or ingested in their crude diet, i.e., responsive 'control' animals already have partially induced enzymes.

Animals↗