Evaluation of benzo(a)pyrene-induced gene mutations in male germ cells.
Polycyclic aromatic hydrocarbons (PAHs) are mutagenic in somatic cells, whereas it remains unclear whether PAHs induce mutations in male germ cells, subsequently increasing health risks in offspring. Although results from the classical specific locus test are negative or inconclusive, recent studies with environmentally exposed animals suggest that PAHs are mutagenic in sperm cells. Therefore, we studied whether benzo(a)pyrene (B[a]P) was able to induce gene mutations in testis and sperm cells of wild-type (Wt) and Xpc(-/-) mice containing the pUR288 lacZ reporter gene. Mice were exposed to B[a]P (13 mg/kg body weight, three times per week) during 1, 4, or 6 weeks and sacrificed 6 weeks after the final exposure to obtain mutations in sperm derived from B[a]P-exposed spermatogonial stem cells. The lacZ gene mutation assay was used to assess mutant frequencies in spleen, testis, and mature sperm, and (32)P-postlabeling was used for the detection of DNA adducts in testis. Successful exposure was confirmed by a dose-related higher mutant frequency in spleen of Xpc(-/-) mice as compared with Wt mice. Mutant frequencies were also increased in all ethyl nitrosourea-exposed samples, which were used as positive control. Although B[a]P-related DNA adducts were detected in testis, mutant frequencies were not increased. On the other hand, B[a]P increased mutant frequencies in sperm of Wt mice, but not in Xpc(-/-) mice, after 6 weeks exposure. Therefore, we conclude that B[a]P can induce gene mutations in spermatogonial cells of mice, but it remains to be elucidated whether these mutations can be transmitted to offspring.
Verhofstad
Nicole
N
Department of Health Risk Analysis and Toxicology, Maastricht University, 6200 MD Maastricht, The Netherlands.
van Oostrom
Conny Th M
CT
Zwart
Edwin
E
Maas
Lou M
LM
van Benthem
Jan
J
van Schooten
Frederik J
FJ
van Steeg
Harry
H
Godschalk
Roger W L
RW
D000818:Animals; D001564:Benzo(a)pyrene / Q000633:toxicity*; D002478:Cells, Cultured; D018736:DNA Adducts / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D017930:Genes, Reporter; D007763:Lac Operon / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009154:Mutation; D013094:Spermatozoa / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D013737:Testis / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology
D018736:DNA Adducts; D004268:DNA-Binding Proteins; C501002:Xpc protein, mouse; D001564:Benzo(a)pyrene