Transcriptional signature of the developing rat testes and ovaries following embryonic exposure to 2,3,7,8-TCDD

We determined global gene changes in immature ovaries and testes in response to an in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure. Microarray analysis was performed using testes and ovaries of the dioxin-exposed dams offspring. One hundred and thirteen genes were differentially expressed in ovaries and 56 genes in testes of 14 and 5 days-old, respectively. Real-time PCR was used to validate and extend data using RNA extracted from 5 to 145-day old rat testes and 3 to 25-day old rat ovaries. A single gene of the classic dioxin battery, i.e., the repressor of the aryl hydrocarbon receptor (Ahrr) was found altered in testes. In contrast, several of them including Cyp1a1, Cyp1b1, Nqo1, and Ahrr were found up-regulated in ovary, pituitary (a different endocrine organ) and liver. In addition to Ahrr, we identified 6 genes targeted by dioxin in both gonads, including the chemokines Cxcl4, Ccl5. Ccl5 gene expression levels were also regulated in pituitary and liver, so as pituitary Cxcl4. Four genes targeted by TCDD in testis and meeting stringent criteria were further surveyed. It included 2 genes with no previous reported function in testis, Art2b, Gzmf, Hpgds and Fgf13. Fgf13 was down-regulated in testis, and pituitary but not in ovary or liver. Interestingly, Art2b and Gzmf were up-regulated in testis, liver and pituitary but not ovary. Finally, Hpgds was unique in that expressed in various tissues it was regulated by TCDD in the gonads but not in the other tissues studied.

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