Tripp K M, Dubois M, Delahaut P, Verstegen J P
University of Florida College of Veterinary Medicine, 2015 SW 16th Avenue, Gainesville, FL 32610, USA.
Theriogenology. 2009 Aug;72(3):365-71. doi: 10.1016/j.theriogenology.2009.03.004. Epub 2009 May 21.
Florida manatees (Trichechus manatus latirostris) have relatively low peripheral concentrations of progesterone (P4). The objective of this study was to determine if these relatively low P4 concentrations are associated with a high ratio of progestin metabolites and to document metabolite concentrations from individual blood samples obtained from manatees during diestrus or pregnancy. Metabolites known to exist in elephants-terrestrial manatee relatives-were targeted. These included 5alpha-reduced progestins (5alpha-pregnane-3,20-dione [5alpha-DHP] and 3alpha-hydroxy-5alpha-pregnan-20-one [5alpha-P3-OH]) and 17alpha-hydroxyprogesterone (17alpha-OHP), which occurs in Asian elephants. An additional, inactive metabolite, 20alpha-hydroxyprogesterone (20alpha-OHP), indicative of P4 overproduction, was also targeted. Progesterone itself was the predominant progestin detected in pregnant and nonpregnant manatee plasma (n = 10) using gas chromatography-mass spectrometry with tandem quadrupole detectors (GC/MS/MS). Progesterone concentrations in pregnant females varied from early (moderate to high) through mid and late (low) pregnancy. Progesterone concentrations ranged from low to high in nonpregnant, nonlactating females. The most commonly detected metabolite was 5alpha-P3-OH (n = 7), which occurred in pregnant (lower limit of detection [LLOD] to high) and nonpregnant (trace to high) females. The 5alpha-DHP metabolite was also detected in pregnant (LLOD to moderate) and nonpregnant (low) females. The 17alpha-OHP metabolite was not detected in any tested female. The 20alpha-OHP metabolite was detected in one nonpregnant, nonlactating, captive female (LLOD). Metabolites were most prevalent during early pregnancy, concurrent with maximum P4 concentrations. Based on their concentrations in peripheral circulation, we inferred that these metabolites may have, opposite to elephants, a limited physiologic role during luteal, pregnant, and nonpregnant phases in the manatee.
佛罗里达海牛（Trichechus manatus latirostris）外周血中孕酮（P4）的浓度相对较低。本研究的目的是确定这些相对较低的P4浓度是否与孕激素代谢物的高比例相关，并记录从处于间情期或妊娠期的海牛个体血液样本中获得的代谢物浓度。研究针对的是已知存在于大象（海牛的陆地近亲）体内的代谢物。这些代谢物包括5α-还原孕激素（5α-孕烷-3,20-二酮[5α-DHP]和3α-羟基-5α-孕烷-20-酮[5α-P3-OH]）以及在亚洲象体内存在的17α-羟基孕酮（17α-OHP）。另外，还针对一种指示P4产生过多的无活性代谢物20α-羟基孕酮（20α-OHP）。使用带串联四极杆检测器的气相色谱-质谱联用仪（GC/MS/MS）检测发现，孕酮本身是在怀孕和未怀孕海牛血浆（n = 10）中检测到的主要孕激素。怀孕雌性海牛体内的孕酮浓度在妊娠早期（中等至高）、中期和晚期（低）有所变化。未怀孕、未哺乳雌性海牛体内的孕酮浓度范围从低到高。最常检测到的代谢物是5α-P3-OH（n = 7），在怀孕（检测下限[LLOD]至高）和未怀孕（痕量至高）雌性海牛中均有出现。在怀孕（LLOD至中等）和未怀孕（低）雌性海牛中也检测到了5α-DHP代谢物。在任何受试雌性海牛中均未检测到17α-OHP代谢物。在一只未怀孕、未哺乳的圈养雌性海牛中检测到了20α-OHP代谢物（LLOD）。代谢物在妊娠早期最为普遍，此时P4浓度也最高。根据它们在外周循环中的浓度，我们推断与大象相反，这些代谢物在海牛的黄体期、妊娠期和非妊娠期可能具有有限的生理作用。
