Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-2120, USA.
Gen Comp Endocrinol. 2013 Apr 1;184:111-9. doi: 10.1016/j.ygcen.2012.12.018. Epub 2013 Jan 18.
We examined associations between thyroid condition, gonadal sex and pubertal development in zebrafish. Seventy-two-hour postfertilization larvae were reared in untreated medium or in the presence of goitrogens (sodium perchlorate, 0.82 mM; methimazole, 0.15 and 0.3 mM) or thyroxine (1 and 10 nM) for 30 days. Thyrocyte height, gonadal sex and gonadal development were histologically determined at 45 and 60 days postfertilization (dpf). Thyrocyte hypertrophy, an index of hypothyroidism, was observed at 45 and 60 dpf in perchlorate-treated but only at 45 dpf in methimazole-treated fish. Similarly, gonadal sex ratios were biased toward ovaries relative to control animals at 45 and 60 dpf in perchlorate-treated fish but only at 45 dpf in methimazole-treated fish. Gonadal sex ratios were biased toward testes at 45 and 60 dpf in thyroxine-treated fish. Spermatogenesis was delayed in testes from goitrogen-treated fish at 60 dpf relative to control values, but was unaffected in testes from thyroxine-treated individuals. Oogenesis seemed to be nonspecifically delayed in all treatments relative to control at 60 dpf. This study confirmed the previously reported association between hypothyroid condition and ovarian-skewed ratios, and hyperthyroid condition and testicular-skewed ratios, and also showed that male pubertal development is specifically delayed by experimental hypothyroidism. The simultaneous recovery from the hypothyroid and ovary-inducing effects of methimazole by 60 dpf (27 days post-treatment) suggests that the ovary-skewing effect of goitrogens is reversible when thyroid conditions return to basal levels before developmental commitment of gonadal sex. Conversely, the masculinizing effect of hyperthyroidism seems to be stable and perhaps permanent.
我们研究了甲状腺状况、性腺性别和斑马鱼青春期发育之间的关系。72 小时后孵化的幼虫在未经处理的培养基或存在致甲状腺肿剂（高氯酸钠，0.82mM；甲巯咪唑，0.15 和 0.3mM）或甲状腺素（1 和 10nM）的情况下培养 30 天。在 45 天和 60 天孵化后（dpf）通过组织学确定甲状腺细胞高度、性腺性别和性腺发育。在高氯酸盐处理的鱼中，在 45 和 60 dpf 观察到甲状腺细胞肥大，这是甲状腺功能减退的一个指标，但在甲巯咪唑处理的鱼中仅在 45 dpf 观察到。同样，在高氯酸盐处理的鱼中，相对于对照动物，在 45 和 60 dpf 时性腺性别比例偏向于卵巢，但在甲巯咪唑处理的鱼中仅在 45 dpf 时偏向于卵巢。在甲状腺素处理的鱼中，在 45 和 60 dpf 时，睾丸性别比例偏向于睾丸。与对照值相比，在 60 dpf 时，来自致甲状腺肿剂处理的鱼的精子发生被延迟，但在来自甲状腺素处理的个体的睾丸中不受影响。在 60 dpf 时，与对照相比，所有处理似乎都特异性地延迟了卵母细胞发生，提示甲巯咪唑的甲状腺功能减退和卵巢诱导作用在 60 dpf（治疗后 27 天）同时恢复，这表明在性腺性别发育承诺之前，甲状腺状况恢复到基础水平时，致甲状腺肿剂的卵巢偏斜作用是可逆的。相反，甲状腺功能亢进的雄性化作用似乎是稳定的，甚至可能是永久性的。
