| Tributyltin (TBT) had been widely used as a biocide in antifouling paints of boat, until it was restricted after discovery of severe damage on marine life, especially mollusk imposex inducing degeneration of population. TBT can deposit in marine biota for many years because of its relative stability, suggesting a possible exposure of humans to TBT in marine diet. Tributyltin Chloride (TBTC) is a main existing form in water. Most experts studied effects of exposure to TBTC on male reproductive system in rats by administrating prepubertal, pubertal or two-generation rats, this study is to explore effects of gestation exposure to TBTC on reproductive system in male offspring rats.Objective: In order to explore effects of gestation exposure to TBTC on development of reproductive organs, function of biosynthesis and secretion of testosterone, spermatogenesis function, activities of enzymes in testes, testicular histopathology and axis of hvpothalamus-pituitary-sex gland in male offspring rats.Methods: Healthy adult male and female Wistar rats were mated. Pregnant rats were randomly divided into four groups (vehicle control, 1, 2.5 and 5mg/kg TBTC) with 4 animals per dose group. TBTC was administered by oral gavage daily from days 12-20 of gestation. The volume of the vehicle used was 5ml/kg body weight. Dams were weighed at the initiation of treatment, once every three days thereafter. The offspring rats were weaned on the postnatal day (PND) 21, and divided based on sexuality. On PND70, 10 male rats randomly selected in each group were killed by decapitation after weighed and trunk blood (about 4-5ml) was collected. Immediately after collection, the blood was centrifuged for 10 min at room temperature and 3000 g·min-(-1) . Aliquots (about 700-800μl) of the supernatant were collected and stored at -20℃. The testis and epididymis were weighed for account of viscera coefficient. Then the left testis was stored at -80℃, the right testis was fixed in neutral formaldehyde balanced solution (4% formaldehyde), and made paraffin section for observation of testicular histopathology, epididymis was stored at -20℃for sperm count. Measurement of concentration of testosterone (T) in serum was performed with enzyme immunoassay, and that of serum luteinizing hormone (LH), follicle stimulating hormone(FSH) and testicular T with radioimmunoasssy. Determinations of enzyme activities were performed with ultraviolet-visible range spectrophotometry.Results: There were no significant differences in number and sex ratio of litter rats between the three treatment groups and the control group.Compared with the control group, body weights gain from PND21-70 were decreased significantly in the 5 and 2.5mg/kg group (P<0.01). Viscera coefficient of testis was increased in a dose-dependent manner. The treatment with 2.5 and 5 mg/kg TBTC led to a statistically significantly increase in viscera coefficient of testis compared with the control (P<0.01). Cauda epididymal sperm counts and concentration of testicular T exhibited significant increase in all treatment groups compared with the control (P<0.01). Viscera coefficient of epididymis and concentration of T in serum did not exhibited significant increase, there was no statistically significant difference between any treatment and the control (P>0.05). TBTC treatment did not have effect on level of LH and FSH in serum compared with the control (P>0.05).It is an increasing trend for activities of lactate dehydrogenase (LDH) and succinate dehydrogenase(SDH) with increasing doses of TBTC. A significant increase was seen in activity of SDH in the 2.5 and 5 mg/kg TBTC, as well as activity of LDH in all treatment groups (P<0.01). Treatment with TBTC did not influence activities of acid phosphatase(ACP) and nitric oxide synthase(NOS) in all treatment groups (P>0.05).We observed that the testis did not appear significant change on histopathology in all treatment groups. Edema was not observed in interstitial tissue, proliferation and necrosis were not found in leydig cells. Spermatogoniums and all degree spermatocytes did not appear vacuolization, increase and necrosis.Conclusions: Gestation of exposure to TBTC could inhibit body weight gain of the offspring rats, and promote development of testis in male rats, increase secretion of testosterone and spermatogenesis function of testis, however, not effect testicular histopathology yet. Furthermore, increasing sperms could induce compensative increase in activities of enzymes such as LDH and SDH in testis, and upregulation of testosterone in testis could not be due to change of hypothalamus- pituitary- sex gland axis. |
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