title: N-hexane inhalation during pregnancy alters DNA promoter methylation in the ovarian granulosa cells of rat offspring.
abstract: The N-hexane-induced impact on the reproductive system of the offspring of animals exposed to n-hexane has caused great concern. Pregnant Wistar rats inhaled 500, 2 500 or 12 500 ppm n-hexane during gestational days 1-20. Clinical characteristics and developmental indices were observed. Ovarian granulosa cells were extracted from F1 rats, the number of follicles was determined in ovarian slices and promoter methylation was assessed using MeDIP-Chip. Several methods were used to analyze the scanned genes, including the Gene Ontology Consortium tools, the DAVID Functional Annotation Clustering Tool, hierarchical clustering and KEGG pathway analysis. The results indicated that the live pups/litter ratio was significantly lowest in the 12 500 ppm group. A significant decrease in secondary follicles and an increase in atresic follicles were observed in the 12 500 ppm group. The number of shared demethylated genes was higher than that of the methylated genes, and the differentially methylated genes were enriched in cell death and apoptosis, cell growth and hormone regulation. The methylation profiles of the offspring from the 500 ppm and control groups were different from those of the 2500 and 12 500 ppm groups. Furthermore, the methylation status of genes in the PI3K-Akt and NF-kappa B signaling pathways was changed after n-hexane exposure. The Cyp11a1, Cyp17a1, Hsd3b1, Cyp1a1 and Srd5a1 promoters were hypermethylated in the n-hexane-exposed groups. These results indicate that the developmental toxicity of n-hexane in F1 ovaries is accompanied by the altered methylation of promoters of genes associated with apoptotic processes and steroid hormone biosynthesis.
authors.affiliation: Department of Occupational and Environmental Health, School of Public Health, Fujian Medical University, Fuzhou, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Jin
authors.initials: J
authors.lastname: Liu
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: Wenxiang
authors.initials: W
authors.lastname: Wang
authors.forename: Shaozheng
authors.initials: S
authors.lastname: Weng
authors.forename: Shihua
authors.initials: S
authors.lastname: Xiao
authors.forename: Huiling
authors.initials: H
authors.lastname: Huang
authors.forename: Wenchang
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001835:Body Weight; D019175:DNA Methylation / Q000187:drug effects*; D005260:Female; D006107:Granulosa Cells / Q000187:drug effects* / Q000378:metabolism; D006586:Hexanes / Q000009:adverse effects*; D019570:Inhalation Exposure / Q000009:adverse effects*; D005810:Multigene Family; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D011247:Pregnancy; D011401:Promoter Regions, Genetic; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction
chemical_list: D006586:Hexanes; D016328:NF-kappa B; C026385:n-hexane; D019869:Phosphatidylinositol 3-Kinases
keywords: DAVID; DNA methylation; inhalation; n-hexane; ovarian granulosa cell