Di-(2 ethylhexyl) phthalate and flutamide alter gene expression in the testis of immature male rats

Thuy Tb Vo,Yeong-Min Yoo,Eui-Man Jung,Kyung-Chul Choi,Vu Hoang Dang,Eui-Bae Jeung,Frank H Yu

doi:10.1186/1477-7827-7-104

Abstract

We previously demonstrated that the androgenic and anti-androgenic effects of endocrine disruptors (EDs) alter reproductive function and exert distinct effects on developing male reproductive organs. To further investigate these effects, we used an immature rat model to examine the effects of di-(2 ethylhexyl) phthalate (DEHP) and flutamide (Flu) on the male reproductive system. Immature male SD rats were treated daily with DEHP and Flu on postnatal days (PNDs) 21 to 35, in a dose-dependent manner. As results, the weights of the testes, prostate, and seminal vesicle and anogenital distances (AGD) decreased significantly in response to high doses of DEHP or Flu. Testosterone (T) levels significantly decreased in all DEHP- treated groups, whereas luteinizing hormone (LH) plasma levels were not altered by any of the two treatments at PND 36. However, treatment with DEHP or Flu induced histopathological changes in the testes, wherein degeneration and disorders of Leydig cells, germ cells and dilatation of tubular lumen were observed in a dose-dependent manner. Conversely, hyperplasia and denseness of Leydig, Sertoli and germ cells were observed in rats given with high doses of Flu. The results by cDNA microarray analysis indicated that 1,272 genes were up-regulated by more than two-fold, and 1,969 genes were down-regulated in response to DEHP, Flu or both EDs. These genes were selected based on their markedly increased or decreased expression levels. These genes have been also classified on the basis of gene ontology (e.g., steroid hormone biosynthetic process, regulation of transcription, signal transduction, metabolic process, biosynthetic process...). Significant decreases in gene expression were observed in steroidogenic genes (i.e., Star, Cyp11a1 and Hsd3b). In addition, the expression of a common set of target genes, including CaBP1, Vav2, Plcd1, Lhx1 and Isoc1, was altered following exposure to EDs, suggesting that they may be marker genes to screen for the anti-androgenic or androgenic effects of EDs. Overall, our results demonstrated that exposure to DEHP, Flu or both EDs resulted in a alteration of gene expression in the testes of immature male rats. Furthermore, the toxicological effects of these EDs on the male reproductive system resulted from their anti-androgenic effects. Taken together, these results provide a new insight into the molecular mechanisms underlying the detrimental impacts of EDs, in regards to anti-androgenic effects in humans and wildlife.

Highlights

Over the past two decades, the detrimental effects of endocrine disruptors (EDs) on wildlife and humans have become a major public health concern
We used an immature rat model of development to examine the adverse effects of di-(2 ethylhexyl) phthalate (DEHP) and Flu on the male reproductive system
Any significant effect in the androgen- dependent organs in animals treated with Testosterone propionate (TP) was not observed even though there is a tendency of gene alterations by TP as seen Figure 1

Summary

Introduction

Over the past two decades, the detrimental effects of endocrine disruptors (EDs) on wildlife and humans have become a major public health concern. A large group of environmental pollutants, are believed to act as agonists or antagonists of androgens and estrogens, which are key hormones involved in many physiological processes. These pollutants have been linked to male reproductive defects in humans, including an increase in the incidence of testicular cancer [1], and declining semen quality [2]. EDs have been linked to developmental problems in the testis and reproductive tract, including reductions in fertility and litter size, induction of cryptorchidism and testicular atrophy [4,5]. Previous reports have suggested that male reproductive system disorders, which often originate during the fetal stage, can appear as testicular dysgenesis syndrome (TDS) after birth [6]

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Results

Conclusion