Biomaterial Database

Altered gene expression: a mechanism for reproductive toxicity in zebrafish exposed to benzo[a]pyrene. 2006

Jennifer L Hoffmann, and James T Oris

Center for Environmental Toxicology and Statistics, Department of Zoology, Miami University, Oxford, OH 45056, USA.

Exposure of fish to polycyclic aromatic hydrocarbons (PAHs) has consistently been shown to have a negative impact on reproduction (e.g. decreased spawning success, decreased ovarian somatic index (OSI) and lower circulating levels of 17beta-estradiol and vitellogenin). While an understanding of the mechanism behind these changes has yet to be fully elucidated, it has been proposed that PAHs can alter the expression of genes important in regulating reproduction. The objectives of this study were to: (1) determine the effect of exposure to waterborne benzo[a]pyrene (B[a]P) (0, 1.5 and 3.0 microg/L) for 56 days on egg production and OSI in female zebrafish (Danio rerio) and (2) determine the effect of B[a]P on transcription of genes involved in reproduction including gonadotropins (follicle stimulating hormone (FSH) and luteinizing hormone (LH)), steroidogenic enzymes (CYP11A1, CYP17, CYP19A1, CYP19A2 and 20beta-HSD), estrogen receptor beta (ERbeta) and vitellogenin. Cytochrome P4501A1 (CYP1A1) was also measured in the liver and heads as an indicator of exposure to B[a]P. A reduction in total egg output was observed in B[a]P exposed fish as well as a decrease in OSI in fish exposed to 3.0 microg/L B[a]P. A significant increase in CYP1A1 expression in the heads as compared to the control was observed whereas no significant difference in CYP1A1 was detected in livers. A significant increase in 20beta-HSD mRNA occurred in heads and pre-vitellogenic oocytes from fish exposed to 1.5 and 3.0 microg/L as compared to the controls. CYP19A2 and vitellogenin were significantly increased following exposure to 3.0 microg/L in the heads and liver, respectively. No effects on the expression of FSH, LH, CYP19A1 or ERbeta were observed. Results from this study demonstrate that reproduction in zebrafish is affected by waterborne exposure to B[a]P and that altered transcription of genes important in regulating reproduction (20beta-HSD, CYP19A2 and vitellogenin) may be one of the underlying mechanisms of B[a]P-induced reproductive toxicity.

UI	MeSH Term	Description	Entries
D007986	Luteinizing Hormone	A major gonadotropin secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Luteinizing hormone regulates steroid production by the interstitial cells of the TESTIS and the OVARY. The preovulatory LUTEINIZING HORMONE surge in females induces OVULATION, and subsequent LUTEINIZATION of the follicle. LUTEINIZING HORMONE consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the three pituitary glycoprotein hormones (TSH, LH and FSH), but the beta subunit is unique and confers its biological specificity.	ICSH (Interstitial Cell Stimulating Hormone),Interstitial Cell-Stimulating Hormone,LH (Luteinizing Hormone),Lutropin,Luteoziman,Luteozyman,Hormone, Interstitial Cell-Stimulating,Hormone, Luteinizing,Interstitial Cell Stimulating Hormone
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D008297	Male		Males
D009865	Oocytes	Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).	Ovocytes,Oocyte,Ovocyte
D010053	Ovary	The reproductive organ (GONADS) in female animals. In vertebrates, the ovary contains two functional parts: the OVARIAN FOLLICLE for the production of female germ cells (OOGENESIS); and the endocrine cells (GRANULOSA CELLS; THECA CELLS; and LUTEAL CELLS) for the production of ESTROGENS and PROGESTERONE.	Ovaries
D010058	Oviposition	The process of laying or shedding fully developed eggs (OVA) from the female body. The term is usually used for certain INSECTS or FISHES with an organ called ovipositor where eggs are stored or deposited before expulsion from the body.	Larviposition,Larvipositions,Ovipositions
D003577	Cytochrome P-450 Enzyme System	A superfamily of hundreds of closely related HEMEPROTEINS found throughout the phylogenetic spectrum, from animals, plants, fungi, to bacteria. They include numerous complex monooxygenases (MIXED FUNCTION OXYGENASES). In animals, these P-450 enzymes serve two major functions: (1) biosynthesis of steroids, fatty acids, and bile acids; (2) metabolism of endogenous and a wide variety of exogenous substrates, such as toxins and drugs (BIOTRANSFORMATION). They are classified, according to their sequence similarities rather than functions, into CYP gene families (>40% homology) and subfamilies (>59% homology). For example, enzymes from the CYP1, CYP2, and CYP3 gene families are responsible for most drug metabolism.	Cytochrome P-450,Cytochrome P-450 Enzyme,Cytochrome P-450-Dependent Monooxygenase,P-450 Enzyme,P450 Enzyme,CYP450 Family,CYP450 Superfamily,Cytochrome P-450 Enzymes,Cytochrome P-450 Families,Cytochrome P-450 Monooxygenase,Cytochrome P-450 Oxygenase,Cytochrome P-450 Superfamily,Cytochrome P450,Cytochrome P450 Superfamily,Cytochrome p450 Families,P-450 Enzymes,P450 Enzymes,Cytochrome P 450,Cytochrome P 450 Dependent Monooxygenase,Cytochrome P 450 Enzyme,Cytochrome P 450 Enzyme System,Cytochrome P 450 Enzymes,Cytochrome P 450 Families,Cytochrome P 450 Monooxygenase,Cytochrome P 450 Oxygenase,Cytochrome P 450 Superfamily,Enzyme, Cytochrome P-450,Enzyme, P-450,Enzyme, P450,Enzymes, Cytochrome P-450,Enzymes, P-450,Enzymes, P450,Monooxygenase, Cytochrome P-450,Monooxygenase, Cytochrome P-450-Dependent,P 450 Enzyme,P 450 Enzymes,P-450 Enzyme, Cytochrome,P-450 Enzymes, Cytochrome,Superfamily, CYP450,Superfamily, Cytochrome P-450,Superfamily, Cytochrome P450
D005260	Female		Females
D005640	Follicle Stimulating Hormone	A major gonadotropin secreted by the adenohypophysis (PITUITARY GLAND, ANTERIOR). Follicle-stimulating hormone stimulates GAMETOGENESIS and the supporting cells such as the ovarian GRANULOSA CELLS, the testicular SERTOLI CELLS, and LEYDIG CELLS. FSH consists of two noncovalently linked subunits, alpha and beta. Within a species, the alpha subunit is common in the three pituitary glycoprotein hormones (TSH, LH, and FSH), but the beta subunit is unique and confers its biological specificity.	FSH (Follicle Stimulating Hormone),Follicle-Stimulating Hormone,Follitropin
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia