Effectsof DEHP In Utero Exposure Onthe Testis Toxicity In Mice

Di-(2-ethylhexyl) phthalate(DEHP) is a commonly used plasticizer. It was worldwide concerned for its adverse effects on the environment and the human body. DEHP widely exist in various plastic products, such as food packaging, toys, medical products, building materials and automotive supplies. DEHP is non-covalently bound to plastics. When heated or repeated used,DEHP will leach out and into spread the environment, causing environmental pollution. DEHP can enter the bodythrough inhalation, ingestion, injection, skin contact and other ways, which is harmful to human health. Study found that, DEHP can lead to neurotoxicity, immunotoxicity,embryotoxicity and reproductive toxicity, among which reproductive toxicity is particularly significant.Testis is reproductive organs of male animal, and its main function is to produce sperm and androgen and to maintain male reproductive function. Testis is the target organs of DEHP and it will inevitably be damaged to lead to crytorchidism or testicular desgenesis syndrome.Study also found that DEHP exposure can cause male reproductive damage symptoms, similar to cryptorchidism and testicular dysgenesis syndrome.In this research we investigated the reproductive defects of testis morphological characteristics, serum hormone level and cell apoptosis by establishing in urtero DEHP exposure model. Mice were exposed to 62.5, 125, 250 and 375 mg/kg/day of DEHP through intraperitoneal injection from gestation day 13 to 19. Control mice were injected same amount of olive oil. The numbers of offspring of F1 generration was recorded and the proportions of female and male in F1 and F2 offspring were calculated. The body and testis weight of male F1 offspring at postnatal day 40, 60 and 90(P40, P60 and P90) were weighed and sperm malformation rate of male F1 offspring at P90 were tested. Hormone levels of T, E, LH and FSH in serum of male F1 offspring at P40, P60 and P90 were detected through radioimmunoassay. The expression of Star and Cyp17a1 which are enzymes of testosterone synthesis in testis were analysed by Weston blot. The morphological characteristics and cell apoptosis of testis from F1 offspring at P90 were detected by HE staining and TUNEL analysis. Finally, the expressions of ABP and P53 in testis were detected by immunohistochemistry.The results showed that:(1)F1 generationtesticular weight at P40, sperm malformation rate in F1 and F2 offspring and the proportion of female and male in F1 offspring increased after DEHP in utero exposure. Vacuolation, multinucleated cell and abnormal cell clumps were appeared in seminiferous tubule, the gaps among seminiferous tubule were enlarged and spermatogenic cycle were disordered in DEHP exposed testis.(2) DEHP caused serum T levels decreased at P40, P60 and P90, serum E levels increased at P40 and serum LH levels increased at P40 and P60. ABP expression pattern in testis were also abnormal at P60 and P90.(3) DEHP can induce spermatogenic cells and sertoli cell apoptosis in a dose dependant manner.The results suggest that DEHP in utero exposure may influence the embryo development and thus the hypothalamus-pituitary-testis axis, which lead to the increasing proporation of female and male offspring mice and abnormal testis development. Finnally, sperm deformity, testicular tissue structure abnormalities, disrupted spermatogenesis and spermatogenic cells and sertoli cell apoptosis were appeared in the post embryonic development and adult testis.This reaserch has studied the effects of DEHP on testis after in utero exposure and provided a reference for further study of reproductive toxicity mechanism of DEHP.