Department of Biology, 220 Bartram Hall, P.O. Box 118525, University of Florida, Gainesville, FL 32611-8525, USA.
Gen Comp Endocrinol. 2012 Jan 15;175(2):251-8. doi: 10.1016/j.ygcen.2011.11.018. Epub 2011 Dec 1.
Oviducts respond to hormonal cues from ovaries with tissue proliferation and differentiation in preparation of transporting and fostering gametes. These responses produce oviducal microenvironments conducive to reproductive success. Here, we investigated changes in circulating plasma sex steroid hormones concentrations and ovarian and oviducal mRNA expression to an in vivo gonadotropin (FSH) challenge in sexually immature, five-month-old alligators. Further, we investigated differences in these observed responses between alligators hatched from eggs collected at a heavily-polluted (Lake Apopka, FL) and minimally-polluted (Lake Woodruff, FL) site. In oviducts, we measured mRNA expression of estrogen, progesterone, and androgen receptors and also beta A and B subunits which homo- or heterodimerize to produce the transforming growth factor activin. In comparison, minimal inhibin alpha subunit mRNA expression suggests that these oviducts produce a primarily activin-dominated signaling milieu. Ovaries responded to a five-day FSH challenge with increased expression of steroidogenic enzyme mRNA which was concomitant with increased circulating sex steroid hormone concentrations. Oviducts in the FSH-challenged Lake Woodruff alligators increased mRNA expression of progesterone and androgen receptors, proliferating cell nuclear antigen, and the activin signaling antagonist follistatin. In contrast, Lake Apopka alligators displayed a diminished increase in ovarian CYP19A1 aromatase expression and no increase in oviducal AR expression, as compared to those observed in Lake Woodruff alligators. These results demonstrate that five-month-old female alligators display an endocrine-responsive ovarian-oviducal axis and environmental pollution exposure may alter these physiological responses.
输卵管会对卵巢发出的激素信号做出反应，通过组织增生和分化来准备运输和培育配子。这些反应产生了有利于生殖成功的输卵管微环境。在这里，我们研究了性未成熟的五个月大的短吻鳄在体内接受促性腺激素（FSH）刺激时，循环血浆中性激素浓度以及卵巢和输卵管 mRNA 表达的变化。此外，我们还研究了在污染严重（佛罗里达州奥帕卡湖）和污染较轻（佛罗里达州伍德鲁夫湖）的产卵地点孵化的短吻鳄之间，这些观察到的反应是否存在差异。在输卵管中，我们测量了雌激素、孕激素和雄激素受体以及 beta A 和 B 亚基的 mRNA 表达，这些亚基可以形成同二聚体或异二聚体，从而产生转化生长因子激活素。相比之下，最小抑制素 alpha 亚基的 mRNA 表达表明，这些输卵管产生的信号环境主要以激活素为主。卵巢对为期五天的 FSH 刺激做出反应，表现为类固醇生成酶 mRNA 的表达增加，同时循环性激素浓度也增加。在接受 FSH 刺激的伍德鲁夫湖短吻鳄的输卵管中，孕激素和雄激素受体、增殖细胞核抗原和激活素信号拮抗剂卵泡抑素的 mRNA 表达增加。相比之下，与伍德鲁夫湖短吻鳄相比，奥帕卡湖短吻鳄的卵巢 CYP19A1 芳香化酶表达增加较少，输卵管 AR 表达没有增加。这些结果表明，五个月大的雌性短吻鳄表现出内分泌反应的卵巢-输卵管轴，而环境污染暴露可能会改变这些生理反应。
