三苯基锡对褐菖鮋卵巢发育的影响

尽管三苯基锡(triphenyltin,TPT)与三丁基锡(tributyltin,TBT)在海洋环境中经常同时存在,但相对于TBT,对TPT的毒性研究还较少。本实验以海洋经济鱼类褐菖鲉(Sebastiscus marmoratus)为对象,研究环境水平TPT对卵巢发育的影响。结果发现,TPT抑制了卵巢发育,表现为性腺指数的降低。TPT还诱导卵巢总脂质水平的增加,而卵巢脂质蓄积可能影响卵巢的正常生殖功能。另外,TPT暴露后,卵巢游离睾酮水平增加,卵巢游离17β-雌二醇水平降低;同时,血清三碘甲腺原氨酸水平降低。因此,TPT对性激素和甲状腺激素水平的影响可能是其抑制卵巢发育的重要机制。实验结果为全面了解TPT产生鱼类生殖毒性效应、途径和机制提供了新的重要的资料。

Effects of triphenyltin on ovarian development in Sebastiscus marmoratus

Organotin compounds,such as triphenyltin(TPT) and tributyltin(TBT),have been extensively used as antifouling agents in paints applied to ships.Aquatic pollution resulting from its usage has been of great concern due to its highly toxic effects on non-targeted marine life.Although TPT and TBT often co-exist in the environment,fewer studies focus on the toxicity of TPT compared with TBT.Recently,an increasing number of studies have reported unexpectedly high levels of TPT in fishes around the world.The effects of TBT on reproductive functions and ovarian development in fishes have been reported.However,whether TPT affects ovarian development in fishes is not clear.Therefore,the study was conducted to investigate the effects of TPT at environmentally relevant concentrations(1,10,and 100 ng·L-1) on ovarian development in Sebastiscus marmoratus,which is an important marine commercial fish.After exposure for 48 d,the body weight was recorded and the gonadosomatic index(GSI) was calculated.The total lipid in the ovary was extracted and determined.The concentrations of testosterone(T) and 17β-estradiol(E2) in the ovaries,and triiodothyronine(T3) and thyroxine in the serum were assayed using radioimmunoassay.The results showed that TPT reduced the GSI.The decreases of GSI induced by TPT indicated inhibition of ovary development and probably had adverse effects on reproduction.TPT exposure also induced lipotoxicity responses in the ovaries,shown as increases of total lipids.The accumulation of ectopic lipids in the ovaries might impact ovarian functions in fish.The free T levels in the ovaries increased after exposure to TPT,while the free E2 levels in the ovaries decreased.E2 derived from the ovarian follicular cells played crucial roles in reproduction of female teleosts.Thus,the decrease of E2 might contribute the inhibition of ovary development induced by TPT.Thyroid hormones were predominantly considered as hormones involved in the catabolic processes of lipids.TPT inhibited the serum T3,which might be related to the lipid accumulation in the ovaries.In addition,it is suggested that thyroid hormones are necessary for gonadal development and reproduction of fishes.Thus,the thyroid disorders might represent an important target of TPT reproductive toxicity in fish.The results of present study provided new information,which was important for fully understanding the reproductive effects and mechanism of TPT,and important evidences for constituting marine environment policies and evaluating effects of organotin compounds on resources of marine fish.