The objective of this study was to reveal the molecular mechanisms involved in the exogenous androgen and aromatase inhibitor‐induced gonadal masculinization of all‐female triploid rainbow trout (RBT) populations. 17α‐methyltestosterone (MT) and letrozole (LET) were used for treatment. The female triploid (XXX) rainbow trout is an effective model to study the molecular mechanism of gonadal masculinization, owing to its tendency towards masculinization under natural conditions. The MT and LET were supplemented with a diet in ethanol at 1.5 mg/kg and 50 mg/kg of food. The treatments did not influence ovary development in female triploid RBT in the early stage (56–80 days post fertilization, i.e. dpf). However, LET could more successfully induce the morphological masculinization of gonads when compared with MT, from 94 dpf to 377 dpf. Gene expression in gonads was analysed after MT and LET treatment. The results showed that expression of male‐specific genes (sdy, dmrt1, sox9 and amh) increased more significantly in the LET group than in the control and MT group, and expression of female‐specific genes (cyp19a1a and foxl2) in LET group tended to decrease significantly. At 377 dpf, significant inhibition of female‐specific genes was shown in the LET group, and male‐specific gene expression increased to levels almost similar to that in diploid male samples. Our preliminary results suggest that the genes involved in gonadal development are pivotal factors in fish sex reversal, and aromatase inhibitor is a more effective inducer of masculinization when compared with androgen.

中文翻译：

---

来曲唑和17α-甲基睾丸激素对全雌三倍体虹鳟性腺发育的影响

这项研究的目的是揭示与外源雄激素和芳香化酶抑制剂诱导的全雌性三倍体虹鳟（RBT）种群性腺男性化有关的分子机制。使用17α-甲基睾丸酮（MT）和来曲唑（LET）进行治疗。雌性三倍体（XXX）虹鳟鱼是研究性腺男性化分子机制的有效模型，因为它在自然条件下倾向于男性化。MT和LET补充有1.5 mg / kg的乙醇饮食和50 mg / kg的食物。在早期（受精后56-80天，即dpf），这些治疗方法不影响雌性三倍体RBT的卵巢发育。然而，与MT相比，LET可以更成功地诱导性腺的形态男性化，从94 dpf到377 dpf。MT和LET处理后，分析性腺中的基因表达。结果表明，男性特异性基因的表达（sdy，dmrt1，sox9和amh）在LET组中比在对照组和MT组中显着增加，并且LET组中女性特异性基因（cyp19a1a和foxl2）的表达倾向于显着下降。在377 dpf时，LET组显示出对女性特异性基因的显着抑制，并且男性特异性基因的表达增加到几乎与二倍体男性样品相似的水平。我们的初步结果表明，与性腺发育有关的基因是鱼类性逆转的关键因素，与雄激素相比，芳香化酶抑制剂是更有效的男性化诱导剂。