Tributyltin (TBT), an organotin acting as aromatase (Cyp19a1) inhibitor, has been found to disrupt gametogenesis and reproductive behaviors in several fish species. However, few studies addressing the mechanisms underlying the impaired gametogenesis and reproduction have been reported. In this study, female adults of zebrafish (Danio rerio) were continuously exposed to two nominal concentrations of TBT (100 and 500 ng/L, actual concentrations: 90.8 ± 1.3 ng/L and 470.3 ± 2.7 ng/L, respectively) for 28 days. After exposures, TBT decreased the total egg number, reduced the hatchability and elevated the mortality of the larvae. Decreased gonadosomatic index (GSI) and altered percentages of follicles in different developmental stages (increased early-stage follicles and reduced mid/late-stage follicles) were also observed in the ovary of TBT-treated fish. TBT also lowered the plasma level of 17β-estradiol and suppressed the expressions of cyp19a1a in the ovary. In treated fish, up-regulated expressions of aldhla2, sycp3 and dmc1 were present in the ovary, indicating an enhanced level of meiosis. The mRNA level of vtg1 was dramatically suppressed in the liver of TBT-treated fish, suggesting an insufficient synthesis of Vtg protein, consistent with the decreased percentage of mid/late-stage follicles in the ovaries. Moreover, TBT significantly suppressed the reproductive behaviors of the female fish (duration of both sexes simultaneously in spawning area, the frequency of meeting and the visit in spawning area) and down-regulated the mRNA levels of genes involved in the regulation of reproductive behaviors (cyp19a1b, gnrh-3 and kiss 2) in the brain. In addition, TBT significantly suppressed the expressions of serotonin-related genes, such as tph2 (encoding serotonin synthase), pet1 (marker of serotonin neuron) and kiss 1 (the modulator of serotonin synthesis), suggesting that TBT might disrupt the non-reproductive behaviors of zebrafish. The present study demonstrated that TBT may impair the reproductive success of zebrafish females probably through disrupting oogenesis, disturbing reproductive behaviors and altering serotonin synthesis. The present study greatly extends our understanding on the reproductive toxicity of TBT on fish.

三丁基锡（TBT）是一种有机锡，可作为芳香酶（Cyp19a1）抑制剂，已破坏几种鱼类的配子发生和生殖行为。然而，很少有研究针对配子发生和繁殖受损的潜在机制进行研究。在这项研究中，斑马鱼成年雌性（Danio rerio）连续暴露于两种名义浓度的TBT（100和500 ng / L，实际浓度：分别为90.8±1.3 ng / L和470.3±2.7 ng / L）28天。暴露后，TBT减少了总卵数，降低了孵化率并提高了幼虫的死亡率。在TBT处理鱼的卵巢中，还观察到了不同发育阶段的性腺体激素指数（GSI）降低和卵泡百分比改变（早期卵泡增加和中期/晚期卵泡减少）。TBT还降低了血浆中17β-雌二醇的水平，并抑制了cyp19a1a在卵巢中的表达。在处理过的鱼中，aldhla2，sycp3和dmc1的表达上调在卵巢中存在，表明减数分裂水平增加。在经TBT处理的鱼的肝脏中，vtg1的mRNA水平被显着抑制，表明Vtg蛋白合成不足，这与卵巢中/晚期卵泡的百分比降低有关。此外，TBT显着抑制了雌性鱼类的生殖行为（产卵区的雌雄同时体持续时间，产卵区的相遇频率和探视频率），并下调了参与生殖行为调控的基因的mRNA水平（cyp19a1b，gnrh -3和亲吻2）在大脑中。此外，TBT显着抑制了血清素相关基因（如tph2）的表达。（编码5-羟色胺合酶），pet1（5-羟色胺神经元标记）和kiss 1（5-羟色胺合成调节剂），表明TBT可能会破坏斑马鱼的非繁殖行为。本研究表明，TBT可能通过破坏卵子发生，干扰生殖行为和改变5-羟色胺的合成而损害斑马鱼雌性的繁殖成功。本研究极大地扩展了我们对TBT对鱼类的生殖毒性的理解。