The effects of an in utero exposure to 2,3,7,8-tetrachloro-dibenzo-p-dioxin on male reproductive function: identification of Ccl5 as a potential marker.

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and dioxin-like compounds are widely encountered toxic substances suspected of interfering with the endocrine systems of humans and wildlife, and of contributing to the loss of fertility. In this study, we determined the changes in testicular gene expression caused by in utero exposure to TCDD along with the intra-testicular testosterone levels, epididymal sperm reserves, daily sperm production (DSP) and testis histology. To this purpose, female pregnant Sprague-Dawley rats orally received TCDD (10, 100 or 200 ng/kg body weight) or vehicle at embryonic day 15, and the offspring was killed throughout development. Hepatic Cyp1a1 gene expression was measured in the offspring to confirm the exposure to TCDD. The gross histology of the testes and intra-testicular testosterone levels were normal among the studied groups. Sperm reserves were altered in 67-day-old rats of the TCDD-200 group, but not in 145-day-old animals or in the other TCDD-exposed groups. Nonetheless, fertility was not altered in males of the TCDD-200 group, and the F2 males generated had normal sperm reserves and DSP. Microarray analysis permitted the identification of eight differentially expressed genes in the 4-week-old testes of the TCDD-200 compared with that of the control group (cut-off value +/- 1.40), including the down-regulated chemokine Ccl5/Rantes. Inhibition of Ccl5/Rantes gene expression was observed throughout development in the TCDD-200 group, and at 67 and 145 days in the TCDD-100 group (animals of younger ages were not examined). Ccl5/Rantes gene expression was mostly confined in Leydig cells. F2 males generated from males of the TCDD-200 group had normal levels of Ccl5/Rantes in testis and Cyp1a1 in liver, which might indicate that Ccl5/Rantes is a marker of TCDD exposure in testis such as Cyp1a1 in liver. In conclusion, we demonstrated a decrease in Ccl5/Rantes RNA levels and a transitory decline in sperm reserves in the testes of rats of TCDD-dosed dams.

Fibroblast growth factor (FGF) 2 and FGF9 mediate mesenchymal-epithelial interactions of peritubular and Sertoli cells in the rat testis.

The role of fibroblast growth factor (FGF) 2 and FGF9 as mediators of cell-cell interactions between Sertoli cells (SCs) and peritubular cells (PCs) was investigated. Using RT-PCR, we demonstrated that SCs and PCs recovered from 20-day-old rats expressed several of the seven FGF receptors (FGFRs), and more specifically the FGFR1 IIIc. FGF2 and FGF9 did not elicit any morphological changes in primary cultures of SCs, nor did they alter the number of SCs in culture. By contrast, changes in shape were observed in FGF2- and FGF9-treated PCs. In addition, FGF2 but not FGF9 enhanced significantly and dose-dependently the number of PCs in culture, indicating that FGF2 was a survival factor for these cells. It was also mitogenic because it enhanced the [3H]thymidine labeling index in PCs. We next examined the effects of FGF2 and FGF9 in a coculture system using 20-day-old rat SCs and PCs, and in an organotypic culture system using XY rat embryonic gonads. In both models, FGF2 and FGF9 were found to promote cellular interactions as evidenced by the extent of cellular reorganization in the coculture system, and cord morphogenesis and growth in the organotypic culture system. A key feature in SC-PC interactions is the synthesis and remodeling of the basement membrane which is co-elaborated by the two cell types. Since basement membrane homeostasis depends upon the coordinated activity of proteinases and inhibitors, the proteinases and inhibitors produced by PCs and SCs degrading or opposing degradation of the major components of the basement membrane were further studied. Specifically, we monitored the metalloproteinases (MMP)-2 and -9 and the tissue inhibitors -1, -2 and -3, the plasminogen activators (PAs) and the PA inhibitor-1, using zymography for the proteinases and Western blots for the cognate inhibitors. Cocultures received FGF or an analog of cAMP in order to prevent cellular reorganization. We found that FGF2 was unique in inducing MMP-9 in coculture. Also, the enhanced levels of the PA inhibitor-1 and the 30 kDa band glycosylated form of tissue inhibitor-3 correlated with the enhanced SC-PC reorganization. It was concluded that FGF2 and FGF9 are morphogens for the formation of testicular cords.