Developmental Toxicity Of Polybrominated Diphenyl Ethers On Reproductive System

Polybrominated Diphenyl Ethers (PBDEs) is a new type of persistent organic pollutants (POPs). Since Main KM reported association between incidence of child cryptorchidism and PBDEs concentration in breast milk in2007, reproductive toxicity of PBDEs has become the new research focus.At present, there is very limited data on the relation between PBDEs exposure and human reproductive development. Although more and more animal trials on reproductive toxicity of PBDEs are rising, little has focused on exposure of PBDEs during puberty and its effects on male reproductive system. Moreover, most of animal trials adopted doses much higher than the daily exposure level of human, which results in insufficient research evidence on PBDEs’ toxicity at low dose.Consequently, based on the birth cohort in rural area of Shandong Province, the present study prospectively studied PBDEs exposure and its effects. Furthermore, animal trials were designed to systematically observe the male reproductive toxicity, especially the impact on sperm development of PBDEs exposure at low dose around puberty. Finally, sertoli cells were cultured in vitro to explore the potential mechanism of PBDEs on reproductive system. Part Ⅰ PBDEs exposure among newborns in rural area of Shandong Province and its developmental and reproductive toxicityObjective:To investigate the PBDEs exposure level among newborns in rural area of Shandong Province and to analysis the relation between PBDEs concentration in cord serum of newborns and the outcome of pregnancy.Methods:PBDEs concentration in cord serum of newborns was detected and the process of pregnancy was recorded. Then, partial correlation was used to analysis the relation between PBDEs concentration in cord serum of newborns and the outcome of pregnancy.Results:At least one type of PBDEs congeners was detected in all serum samples (n=176) from newborns. BDE-100(r=0.607, P<0.01), BDE-47(r=0.352, P<0.05), BDE-99(r=0.412, P<0.05) levels in serum of newborns were significantly positively correlated with the number of artificial abortion of their mothers due to abnormality of fetus. Newborns’serum BDE-153levels were significantly positively correlated with their height (r=0.452, P<0.01).Conclusion:Newborns in rural area of Shandong province are widely exposed to PBDEs and PBDEs levels in cord serum of newborns may correlate with the adverse outcome of pregnancy.Part Ⅱ Effects of BDE-209exposure during puberty on reproductive system in male ratsObjective:To study the effects of BDE-209exposure during puberty on sexual development, reproductive organ and gland development, sperm production and reproductive endocrine function in male rats. Methods:Twenty-four male SD rats (4weeks old) were randomly divided into control group and3BDE-209treatment groups (2,10,50mg/kg.d). Rats were exposed to BDE-209by gavage once a day, continuously for one month. In the end, biological samples were collected and detected.Results:(1) Rats in50mg/kg BDE-209treatment groups showed significant lower testis antioxidant enzyme activity (SOD, GSH-Px) and marker enzymes activity (AKP) than that of control group as well as vacuolar degeneration in testis biopsy. No significant difference was found between the treatment groups and control group in body weight, anogenital distance, penis-preputial separation time and organ coefficients.(2) Rats’ sperm activity significantly declined as the dose of BDE-209increased (P<0.05) among treatment groups, among which the50mg/kg group had the lowest sperm activity (P<0.05). The sperm motility and the percentage of progressive sperm also declined among the treatment groups, among which the sperm motility showed significant difference between the50mg/kg BDE-209group and control group (P<0.05). The percentage of abnormal sperm in treatment groups was significantly higher than that in control group (P<0.05). The sperm concentration showed no significant difference between the treatment groups and control group.(3) No significant change was found in the levels of serum testosterone, estradiol and testosterone in testis tissue between the treatment groups and control group (P>0.05).Conclusion:In the present study, BDE-209exposure during puberty results in testis morphological and function change and has significant adverse effects on the process of sperm development, which includes increased percentage of abnormal sperm, decreased sperm motility and declined sperm velocity. Part Ⅲ The cytotoxicity of BDE-209on sertoli cells of rats in vitroObjective:To study the cytotoxicity of BDE-209on sertoli cells of rats in vitro.Methods:Sertoli cells from18-day old SD rats were chosen for primary culture and exposed with BDE-209for24hours. Cell concentration was measured with MTT and apoptosis of sertoli cells were detected with Annexin V-FITC kit.Results:(1) Sertoli cells entered the exponential phase after36hours of culture and the period of48-72hours was the suitable window phase for treatment. After exposed with BDE-209for24hours, the cell survival rate declined with the dose increased. Decline of relative survival rate of sertoli cell showed significant difference between the treatment groups (BDE-2095≥30μg/ml) and control group.(2) The activities of T-AOC and SOD in sertoli cells significantly declined in the10μg/ml and20μg/ml BDE-209treatment groups than that of control group (P<0.05).(3) The percentage of apoptotic cells increased after BDE-209treatment for24hours and was significantly higher in the treatment groups (BDE-209≥20μg/m) than in control group (P<0.05).Conclusion:BDE-209may have cytotoxic effects on sertoli cells cultured in vitro, which include that BDE-209may cause apoptosis of sertoli cells.