The effects of di-2-ethylhexyl phthalate on testicular ultrastructure and hormone-regulated gene expression in male rats.

The objective of this study is to determine testicular pathological damage and explore its molecular mechanisms after di-2-ethylhexyl phthalate (DEHP) treatment. A total of 40 healthy 5-week-old male Sprague-Dawley rats were randomly divided into four groups, which received intragastric administration of 0 mg kg-1, 100 mg kg-1, 500 mg kg-1 and 1500 mg kg-1 DEHP for six continuous weeks. After DEHP treatment, the testes wet weight and testes coefficient were calculated, the histopathological changes of the testes were examined by HE staining and the testicular ultrastructure was examined by transmission electron microscopy. The gene expression levels were analyzed by quantitative RT-PCR and the protein expression levels were analyzed by western blotting. Both 500 mg kg-1 and 1500 mg kg-1 DEPH treatments decreased the wet weight of the testes and testes coefficient, due to vacuoles in Sertoli cells, broken mitochondrial ridges, and degranulation. Quantitative RT-PCR showed that the relative gene expression levels of steroidogenic acute regulatory protein (StAR) and 3β-hydroxysteroid dehydrogenase (3β-HSD) increased in the 100 mg kg-1, 500 mg kg-1, and 1500 mg kg-1 DEHP groups, respectively. Additionally, 17β-hydroxysteroid dehydrogenase (17β-HSD) expression levels were increased in the 1500 mg kg-1 DEHP treatment group. Gonadotropin-releasing hormone (GnRH) expression levels were decreased with 500 mg kg-1 and 1500 mg kg-1 DEHP treatments. DEHP induced serious pathological damage and ultrastructure changes in rat testes, caused endocrine disorders, interfered with the synthesis of male hormones, and ultimately led to male reproductive system dysfunction.