Real-time PCR array to study effects of chemicals on the Hypothalamic-Pituitary-Gonadal axis of the Japanese medaka.
This paper describes the development and validation of a PCR array for studying chemical-induced effects on gene expression of selected endocrine pathways along the hypothalamic-pituitary-gonadal (HPG) axis of the small, oviparous fish, the Japanese medaka (Oryzias latipes). The Japanese medaka HPG-PCR array combines the quantitative performance of SYBR Green-based real-time PCR with the multiple gene profiling capabilities of a microarray to examine expression profiles of 36 genes associated with endocrine pathways in brain, liver and gonad. The performance of the Japanese medaka HPG-PCR array was evaluated by examining effects of two model compounds, the synthetic estrogen, 17alpha-ethinylestradiol (EE2) and the anabolic androgen, 17beta-trenbolone (TRB) on the HPG axis of the Japanese medaka. Four-month-old medaka was exposed to three concentrations of EE2 (5, 50, 500 ng/L) or TRB (50, 500, 5000 ng/L) for 7d in a static renewal exposure system. A pathway-based approach was implemented to analyze and visualize concentration-dependent mRNA expression in the HPG axis of Japanese medaka. The compensatory response to EE2 exposure included the down-regulation of male brain GnRH RI and testicular CYP17. The down-regulation of AR-alpha expression in brain of EE2-exposed males was associated with suppression of male sexual behavior. Compensatory responses to TRB in the female HPG axis included up-regulation of brain GnRH RII and ovary steroidogenic CYP19A. Overall, the results suggested that the Japanese medaka HPG-PCR array has potential not only as a screening tool of potential endocrine-disrupting chemicals but also in elucidating mechanisms of action.
Department of Zoology, National Food Safety & Toxicology Center, Michigan State University, East Lansing, 218c, MI 48824, USA. howard50003250@yahoo.com <howard50003250@yahoo.com>
Xiaowei
X
Zhang
Markus
M
Hecker
June-Woo
JW
Park
Amber R
AR
Tompsett
John
J
Newsted
Kei
K
Nakayama
Paul D
PD
Jones
Doris
D
Au
Richard
R
Kong
Rudolf S S
RS
Wu
John P
JP
Giesy
D000818:Animals; D001141:Aromatase / Q000096:biosynthesis / Q000235:genetics; D004997:Ethinyl Estradiol / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D020869:Gene Expression Profiling / Q000379:methods; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects*; D008297:Male; D009990:Oryzias / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010913:Pituitary-Adrenal System / Q000187:drug effects*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D011944:Receptors, Androgen / Q000096:biosynthesis / Q000235:genetics; D011966:Receptors, LHRH / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D018709:Statistics, Nonparametric; D013254:Steroid 17-alpha-Hydroxylase / Q000096:biosynthesis / Q000235:genetics; D014204:Trenbolone Acetate / Q000494:pharmacology*
D012333:RNA, Messenger; D011944:Receptors, Androgen; D011966:Receptors, LHRH; D004997:Ethinyl Estradiol; D001141:Aromatase; D013254:Steroid 17-alpha-Hydroxylase; D014204:Trenbolone Acetate