ABSTRACT
<p><b>OBJECTIVE</b>To explore the effects of di-butyl phthalate (DBP) on the reproductive system of adolescent male rats.</p><p><b>METHODS</b>Sprague-Dawley (SD) rats aged 5 weeks were assigned to receive corn oil (vehicle control) or DBP orally at 10, 100 and 500 mg/(kg x d) for 30 days. After the exposure, the testis, epididymis, liver and pituitary of the rats were weighted and their ratios to the body weight obtained. Histopathological changes of the testis and epididymis were examined by Hematoxylin-eosin staining, the levels of testosterone (T), luteinizing hormone (LH) and follicle stimulating hormone (FSH) in the serum were measured by radioimmunoassay, and the relative mRNA expressions of the steroidogenesis acute regulatory protein (StAR), proliferating cell nuclear antigen (PCNA), cytochrome P450 cholesterol side chain cleavage enzyme (P450scc) and scavenger receptor (SR) were detected by real-time quantitative RT-PCR.</p><p><b>RESULTS</b>DBP induced significant histopathological changes in the testicular tissue at 100 and 500 mg/(kg x d), and decreased the testicular and epididymal weights, inhibited the mRNA expressions of StAR and PCNA, reduced the levels of T and LH, and elevated the level of FSH at 500 mg/(kg x d). At the dose of 10 mg/(kg x d), DBP increased serum LH and FSH and the mRNA expression of P450scc. While the SR mRNA expression showed no significant changes in all the groups.</p><p><b>CONCLUSION</b>High level of DBP has apparent toxic effect on reproductive system of male rats. Low - dose DBP can increase the level of serum gonadotropin LH and affect the mRNA expression of P450scc in the testis.</p>