Suppression of steroidogenic enzyme expression during androgen-induced sex reversal in Nile tilapia (Oreochromis niloticus)
Suppression of steroidogenic enzyme expression during androgen-induced sex reversal in Nile tilapia (Oreochromis niloticus)
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DOI：
10.1016/j.ygcen.2005.06.014
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发表时间：
2006-01-01
影响因子：
2.7
通讯作者：
Nagahama, Y
中科院分区：
文献类型：
--
作者：
Bhandari, RK;Nakamura, M;Nagahama, Y
外源性类固醇激素显著改变鱼类的性别分化。这些变化涉及的内分泌和分子机制尚不清楚。为了进一步阐明雄激素诱导的睾丸分化的机制，我们用甲基睾酮（NIT，剂量为50 μ g/g饲料）处理雌性尼罗罗非鱼，并检测性腺中P450胆固醇侧链裂解酶、3 β-羟基类固醇脱氢酶和细胞色素P450芳香化酶（P450 arom）的表达。MT处理导致100%雄性化。未经处理的鱼表现出正常的卵巢分化，所有三种类固醇生成酶的强表达。在MT处理的鱼的性腺中，所有三种类固醇生成酶的表达在15天内减弱，并在处理后30天内完全消失。我们的研究结果表明，外源性雄激素治疗抑制关键类固醇生成酶的表达，包括P450 arom在整个性别分化的罗非鱼，从而雄性化的动物。是否芳香化酶的缺乏或雄激素的存在是睾丸分化的原因仍有待确定。(c)2005年爱思唯尔公司All rights reserved.
Exogenous sex steroids markedly alter sex differentiation in fish. The endocrine and molecular mechanisms involved in these changes remain unclear. To further clarify the mechanism of androgen-induced testicular differentiation, we treated female tilapia Oreochromis niloticus with methyltestosterone (NIT at a dose of 50 mu g/g diet) and examined the expression of P450 cholesterol-sidechain-cleavage, 3 beta-hydroxysteroid dehydrogenase, and cytochrome P450 aromatase (P450arom) in the gonads. MT treatment resulted in 100% masculinization. Untreated fish showed normal ovarian differentiation with strong expression of all three steroidogenic enzymes. In gonads of MT-treated fish, expression of all three steroidogenic enzymes was attenuated within 15 days and completely disappeared within 30 days of treatment. Our results indicate that exogenous androgen treatment suppresses the expression of key steroidogenic enzymes, including P450arom throughout sex differentiation in tilapia, thus masculinizing the animal. Whether the absence of aromatase or the presence of androgens is responsible for testicular differentiation remains to be determined. (c) 2005 Elsevier Inc. All rights reserved.