Localization and divergent profiles of estrogen receptors and aromatase in the vocal and auditory networks of a fish with alternative mating tactics.

Estrogens play a salient role in the development and maintenance of both male and female nervous systems and behaviors. The plainfin midshipman (Porichthys notatus), a teleost fish, has two male reproductive morphs that follow alternative mating tactics and diverge in multiple somatic, hormonal and neural traits, including the central control of morph-specific vocal behaviors. After we identified duplicate estrogen receptors (ERβ1 and ERβ2) in midshipman, we developed antibodies to localize protein expression in the central vocal-acoustic networks and saccule, the auditory division of the inner ear. As in other teleost species, ERβ1 and ERβ2 were robustly expressed in the telencephalon and hypothalamus in vocal-acoustic and other brain regions shown previously to exhibit strong expression of ERα and aromatase (estrogen synthetase, CYP19) in midshipman. Like aromatase, ERβ1 label co-localized with glial fibrillary acidic protein (GFAP) in telencephalic radial glial cells. Quantitative PCR revealed similar patterns of transcript abundance across reproductive morphs for ERβ1, ERβ2, ERα and aromatase in the forebrain and saccule. In contrast, transcript abundance for ERs and aromatase varied significantly between morphs in and around the sexually polymorphic vocal motor nucleus (VMN). Together, the results suggest that VMN is the major estrogen target within the estrogen-sensitive hindbrain vocal network that directly determines the duration, frequency and amplitude of morph-specific vocalizations. Comparable regional differences in steroid receptor abundances likely regulate morph-specific behaviors in males and females of other species exhibiting alternative reproductive tactics.

雌激素在雄性和雌性神经系统及行为的发育和维持中都起着显著作用。平鳍美洲蟾鱼（Porichthys notatus）是一种硬骨鱼，具有两种雄性繁殖形态，它们遵循不同的交配策略，并且在多种躯体、激素和神经特征上存在差异，包括对特定形态发声行为的中枢控制。在我们确定蟾鱼体内存在重复的雌激素受体（ERβ1和ERβ2）之后，我们制备了抗体以定位其在中枢发声 - 听觉网络以及内耳的听觉部分球囊中的蛋白质表达。与其他硬骨鱼物种一样，ERβ1和ERβ2在发声 - 听觉及其他脑区的端脑和下丘脑中强烈表达，此前已表明在蟾鱼中这些区域ERα和芳香化酶（雌激素合成酶，CYP19）有强烈表达。与芳香化酶类似，ERβ1标记与端脑放射状胶质细胞中的胶质纤维酸性蛋白（GFAP）共定位。定量PCR显示，在前脑和球囊中，ERβ1、ERβ2、ERα和芳香化酶在不同繁殖形态间的转录本丰度模式相似。相比之下，在性多态的发声运动核（VMN）及其周围，雌激素受体和芳香化酶的转录本丰度在不同形态之间存在显著差异。总之，这些结果表明VMN是雌激素敏感的后脑发声网络内的主要雌激素靶点，它直接决定特定形态发声的持续时间、频率和振幅。类固醇受体丰度的类似区域差异可能调节其他具有不同繁殖策略的物种的雄性和雌性的特定形态行为。