Lema Sean C, Chow Michelle I, Dittman Andrew H, May Darran, Housh Madeline J
Biological Sciences Department, Center for Coastal Marine Sciences, California Polytechnic State University, San Luis Obispo, CA, USA.
Biological Sciences Department, Center for Coastal Marine Sciences, California Polytechnic State University, San Luis Obispo, CA, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2022 Oct;272:111280. doi: 10.1016/j.cbpa.2022.111280. Epub 2022 Jul 25.
Many fish experience diminished reproductive performance under atypically high or prolonged elevations of temperature. Such high temperature inhibition of reproduction comes about in part from altered stimulation of gametogenesis by the hypothalamic-pituitary-gonadal (HPG) endocrine axis. Elevated temperatures have also been shown to affect thyroid hormone (TH) signaling, and altered TH status under high temperatures may impact gametogenesis via crosstalk with HPG axis pathways. Here, we examined effects of temperature and 3'-triiodo--thyronine (T) on pathways for gonadal steroidogenesis and gametogenesis in Amargosa pupfish (Cyprinodon nevadensis amargosae) from two allopatric populations: 1) the Amargosa River - a highly variable temperature habitat, and 2) Tecopa Bore - an invariably warm groundwater-fed marsh. These populations were previously shown to differ in TH signaling profiles both in the wild and under common laboratory conditions. Sexually-mature pupfish from each population were maintained at 24 °C or 34 °C for 88 days, after which a subset of fish was treated with T for 18-24 h. In both populations, mRNA abundances for follicle-stimulating hormone receptor and luteinizing hormone receptor were higher in the ovary and testis at 24 °C compared to 34 °C. Females from Tecopa Bore - but not from the Amargosa River - also had greater ovarian transcript abundances for steroidogenic enzymes cytochrome P450 aromatase, 3β-hydroxysteroid dehydrogenase, and 17β-hydroxysteroid dehydrogenase at 24 °C compared to 34 °C, as well as higher liver mRNA levels of vitellogenins and choriogenins at cooler temperature. Transcript abundances for estrogen receptors esr1, esr2a, and esr2b were reduced at 34 °C in Amargosa River females, but not in Tecopa Bore females. T augmented gonadal gene transcript levels for steroid acute regulatory protein (StAR) transporter in both sexes and populations. T also downregulated liver estrogen receptor mRNAs in females from the warmer Tecopa Bore habitat only, suggesting T modulation of liver E sensitivity as a possible mechanism whereby temperature-induced changes in TH status may contribute to shifts in thermal sensitivity for oogenesis.
许多鱼类在非典型的高温或长时间温度升高情况下，生殖性能会下降。这种高温对繁殖的抑制部分源于下丘脑 - 垂体 - 性腺（HPG）内分泌轴对配子发生刺激的改变。高温也已被证明会影响甲状腺激素（TH）信号传导，高温下TH状态的改变可能通过与HPG轴途径的相互作用影响配子发生。在此，我们研究了温度和3'-三碘甲状腺原氨酸（T3）对来自两个异域种群的阿马戈萨鳉鱼（Cyprinodon nevadensis amargosae）性腺类固醇生成和配子发生途径的影响：1）阿马戈萨河——一个温度变化很大的栖息地，以及2）特科帕泉——一个始终温暖的由地下水滋养的沼泽地。先前已表明，这些种群在野外和常见实验室条件下的TH信号特征均存在差异。来自每个种群的性成熟鳉鱼在24°C或34°C下饲养88天，之后一部分鱼用T3处理18 - 24小时。在两个种群中，与34°C相比，24°C时卵巢和睾丸中促卵泡激素受体和促黄体生成素受体的mRNA丰度更高。与34°C相比，来自特科帕泉的雌性——而非阿马戈萨河的雌性——在24°C时卵巢中类固醇生成酶细胞色素P450芳香化酶、3β - 羟基类固醇脱氢酶和17β - 羟基类固醇脱氢酶的转录本丰度也更高，并且在较低温度下肝脏中卵黄蛋白原和卵壳蛋白原的mRNA水平也更高。阿马戈萨河雌性在34°C时雌激素受体esr1、esr2a和esr2b的转录本丰度降低，但特科帕泉雌性则没有。T3增加了两个性别和种群中性腺类固醇急性调节蛋白（StAR）转运体的基因转录水平。T3还仅下调了来自较温暖的特科帕泉栖息地雌性肝脏中的雌激素受体mRNA，这表明T3对肝脏雌激素敏感性的调节可能是一种机制，通过这种机制温度诱导的TH状态变化可能导致卵子发生热敏感性的改变。
