Testicular Growth and Regression Are Not Correlated With Dio2 Expression in a Wild Male Songbird, Sturnus vulgaris, Exposed to Natural Changes in Photoperiod
Testicular Growth and Regression Are Not Correlated With Dio2 Expression in a Wild Male Songbird, Sturnus vulgaris, Exposed to Natural Changes in Photoperiod
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DOI：
10.1210/en.2013-1093
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发表时间：
2013-05-01
期刊：
影响因子：
4.8
通讯作者：
Perfito, Nicole
中科院分区：
文献类型：
--
作者：
Bentley, George E.;Tucker, Shanna;Perfito, Nicole
鸟类和哺乳动物季节性繁殖的时间是通过改变白天的长度来调节的，并且取决于甲状腺激素的存在。已经提出了一种甲状腺依赖性控制季节性的机制，其中暴露于长日照长度诱导T-4快速局部转化为其生物活性形式T-3，通过上调大脑中的2型碘甲腺原氨酸脱碘酶（Dio 2）和下调Dio 3（使T-3失活）。这种变化与鹌鹑促性腺激素释放和性腺生长有关。这一机制在一个驯化的物种（鹌鹑）暴露在一天的长度不自然的急性变化阐明。在这里，我们调查了Dio 2/Dio 3机制在野生物种，欧洲椋鸟，自然变化的白天长度。虽然Dio 2的表达随季节变化，但Dio 3没有。我们没有发现Dio 2与光周期，季节性调节GnRH，或睾丸体积相关。观察到的差异，从椋鸟和鹌鹑的数据可能是一个结果，从创始人种群的遗传漂变，或生殖季节性的差异，除了或而不是由驯化或使用人工改变光周期。总的来说，数据表明，在一个野生物种暴露于自然变化的一天的长度，目前提出的机制，光周期定时是不那么简单，比普遍接受的，可能不像以前认为的那样普遍适用。（内分泌学154：1813-1819，2013）
Timing of seasonal breeding in birds and mammals is regulated by changing the day length and is dependent on the presence of thyroid hormones. A mechanism for thyroid-dependent control of seasonality has been proposed, in which exposure to long day lengths induces rapid local conversion of T-4 to its bioactive form, T-3, via the up-regulation of the enzyme type 2 iodothyronine deiodinase (Dio2) in the brain, and the down-regulation of Dio3 (which inactivates T-3). Such changes were correlated with gonadotropin release and gonadal growth in quail. This mechanism was elucidated in a domesticated species (quail) exposed to unnatural acute changes in day length. Here we investigated the Dio2/Dio3 mechanism in a wild species, the European starling, under naturally changing day length. Although Dio2 expression varied seasonally, Dio3 did not. We found no correlation of Dio2 with photoperiod, seasonal regulation of GnRH, or testicular volume. The observed differences in data from starlings and quail could be a result of phylogeny, genetic drift from founder populations, or differences in reproductive seasonality in addition to or instead of arising from domestication or use of artificially changing photoperiods. Overall, the data indicate that in a wild species exposed to natural changes in day length, the current proposed mechanism for photoperiodic timing is less straightforward than is generally accepted and might not be as universally applicable as previously thought. (Endocrinology 154: 1813-1819, 2013)