Zhang Peijun, Yang Yong, Han Jiabo, Lu Zhichuang, Wang Limei, Tian Jiashen, Wang Qinguo
Aquatic Mammals Conservation Department, Liaoning Ocean and Fisheries Science Research Institute, Dalian, China; Liaoning Key Laboratory of Marine Biological Resources and Ecology, Dalian, China.
Dalian Sun Asia Tourism Holding Co., Ltd., Dalian, China.
Theriogenology. 2014 Aug;82(3):475-480.e4. doi: 10.1016/j.theriogenology.2014.05.013. Epub 2014 May 21.
Spotted seals (Phoca largha) are ice-breeding phocid found in eight different breeding colonies all over the world. They exhibit a seasonal breeding pattern, with annual and synchronous cycles; however, little is known about their reproductive endocrinology. In this study, we measured serum testosterone, progesterone, and 17β-estradiol concentrations in captive spotted seals (simple number: female n = 68; male n = 89) throughout a full reproductive cycle. Males that were older than 4 years had significant testosterone fluctuations and were, therefore, classified as sexually mature. These animals show significant seasonal changes in testosterone levels, with average peak concentrations of 10.81 ± 9.57 nmol/L (±SD) from November to February, compared with mean concentrations of 1.42 ± 3.09 nmol/L throughout the remainder of the year. Females that reported a significant variation in progesterone concentrations and were older than 4 years were considered to be sexually mature. In these females, progesterone levels increased in February, remained elevated for 7 months with a mean value of 37.39 ± 17.03 nmol/L, and then dropped to 0.74 ± 0.54 nmol/L. Serum 17β-estradiol levels were also found to be significantly increased in January, remained so for 8 months (15.80 ± 14.15 ng/L), and then declined after August (7.77 ± 6.78 ng/L). In seals, mating typically occurs in February and March, 1 month after the observed peaks in testosterone and estradiol concentrations and corresponding to the increase in progesterone. A moderate positive correlation between testosterone and progesterone concentrations in sexually mature males was also observed (Spearman rho, r = 0.63, P < 0.01). In sexually immature females, progesterone and estradiol concentrations were found to be significantly lower than those in mature females. Finally, the observed patterns of estradiol and progesterone in sexually mature females suggest that embryonic diapause or successful implantation occurs in August.
斑海豹（Phoca largha）是一种在全球八个不同繁殖地进行冰上繁殖的海豹科动物。它们呈现出季节性繁殖模式，具有年度同步周期；然而，关于它们的生殖内分泌学却知之甚少。在本研究中，我们在一个完整的繁殖周期内测量了圈养斑海豹（数量：雌性n = 68；雄性n = 89）血清中的睾酮、孕酮和17β - 雌二醇浓度。4岁以上的雄性海豹睾酮水平有显著波动，因此被归类为性成熟。这些动物的睾酮水平呈现出显著的季节性变化，11月至2月的平均峰值浓度为10.81±9.57 nmol/L（±标准差），而一年中其余时间的平均浓度为1.42±3.09 nmol/L。报告孕酮浓度有显著变化且年龄大于4岁的雌性被认为是性成熟。在这些雌性中，孕酮水平在2月升高，持续7个月保持在较高水平，平均值为37.39±17.03 nmol/L，然后降至0.74±0.54 nmol/L。血清17β - 雌二醇水平在1月也显著升高，持续8个月（15.80±14.15 ng/L），8月后下降（7.77±6.78 ng/L）。在海豹中，交配通常发生在2月和3月，在观察到的睾酮和雌二醇浓度峰值后1个月，且与孕酮的增加相对应。在性成熟雄性中还观察到睾酮和孕酮浓度之间存在中度正相关（斯皮尔曼等级相关系数，r = 0.63，P < 0.01）。在性未成熟雌性中，发现孕酮和雌二醇浓度显著低于成熟雌性。最后，在性成熟雌性中观察到的雌二醇和孕酮模式表明，胚胎滞育或成功着床发生在8月。
