227 AN ALTERATION IN GENE EXPRESSION PATTERNS INDUCED BY DI-(2 ETHYLHEXYL) PHTHALATE AND FLUTAMIDE IN THE TESTIS OF IMMATURE MALE RATS

Abstract

In a previous study, we demonstrated that although endocrine disruptors (EDs) with androgenic and anti-androgenic effects may alter reproductive function, their effects on the developing male reproductive organs may be distinct. To continue this line of study, we treated immature rats to examine the adverse 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/or Flu at postnatal day (PND) 21 to 35 in a dose-dependent manner, and the changes evoked by these EDs were determined by differences in male reproductive tract and other organ weights, testicular histology, and serum LH and testosterone levels in combination with global microarray analysis. Interestingly, the testes, prostate, seminal vesicle weight, and anogenital distances were significantly decreased in response to the highest dose of DEHP and Flu. There were no differences in serum LH and testosterone concentration at PND 35 for immature male rats exposed to DEHP and/or Flu. However, treatment with DEHP and/or Flu caused histopathological changes in testes in which the degeneration and denseness of germ cells and/or dilatation of the tubular lumen were observed in response to the high dose [500 mg kg^–1 of body weight (BW)] of DEHP and medium dose (10 mg kg^–1 of BW) of Flu. Additionally, the results from cDNA microarray indicated that 1272 genes were up-regulated (more than 2-fold) and 1969 genes were down-regulated in response to DEPH and/or Flu. These genes were identified based on their roles in some physiological processes (i.e. lipid and cholesterol homeostasis, steroidogenesis, sex determination, and calcium signal transduction). The significant decreases were observed in the expressions of steroidogenic genes (i.e. Star, Cyp11a1, or Hsd3b). In addition, a common set of targeting genes, including CaBP1, Vav2, Plcd1, Lhx1, and Isoc1, were altered following EDs exposure, suggesting a potential set of biomarker genes for screening anti-androgenic and/or androgenicity of EDs. Taken together, we demonstrated that exposure to DEHP and/or Flu resulted in a temporal alteration in gene expression profile in the testes of immature male rats, and their toxicological effects on male reproductive system are distinct depending on their anti-androgenicity, suggesting new insight into molecular mechanism(s) underlying detrimental impacts of EDs with anti-androgenic activities in human and wildlife.