Hodges J K, Heistermann M, Beard A, van Aarde R J
Department of Reproductive Biology, German Primate Centre, Göttingen, Germany.
Biol Reprod. 1997 Mar;56(3):640-6. doi: 10.1095/biolreprod56.3.640.
The 5 alpha-reduced metabolites 5 alpha-pregnane-3,20-dione (5 alpha-DHP) and 3 alpha-hydroxy-5 alpha-pregnan-20-one (5 alpha-P-3 alpha-OH) are the principal progestins biosynthesized by the African elephant corpus luteum. The aim of the present study was to determine luteal and circulating concentrations of these 5 alpha-reduced progestins in relation to progesterone (P4) and to examine whether their measurement reflects corpus luteum function. Ovarian (luteal) tissue (30 corpora lutea and 3 corpora rubra from 8 animals) and plasma samples (30 animals) were collected from pregnant and nonpregnant adult elephants shot in the Kruger National Park. Specific immunological measurement for both 5 alpha-reduced progestins and P4 was achieved by enzymeimmunoassay of tissue and plasma extracts following purification by HPLC. Mean (+/- SEM) luteal concentrations of 5 alpha-DHP and 5 alpha-P-3 alpha-OH were 79.5 +/- 9.4 micrograms/g and 196.5 +/- 24.8 micrograms/g, respectively, approximately 2-3 orders of magnitude higher than those of P4 (mean +/- SEM, 0.16 +/- 0.01 microgram/g). Whereas 5 alpha-reduced progestin concentrations tended to be lower in corpora lutea from late pregnancy compared with earlier stages and were lowest in corpora rubra, P4 levels were similar in all tissues/stages examined. The 5 alpha-reduced progestins also predominated over P4 in plasma (mean 5 alpha-DHP:P4 and 5 alpha-P-3 alpha-OH:P4 ratios 20.3 and 13.4, respectively). Similar to results for luteal tissue, plasma concentrations of 5 alpha-reduced progestins, but not of P4, were lower in late pregnancy than in earlier gestation stages and in nonpregnant animals. Moreover, plasma levels of both 5 alpha-reduced metabolites were negatively correlated with gestation age, whereas those of P4 were not. Levels of 5 alpha-reduced metabolites (without chromatography) were also measured in weekly blood samples throughout two complete ovarian cycles in one captive female. Both measurements showed a cyclic profile (similar to that of P4) with a luteal-phase elevation of 10- to 15-fold. The results indicate that 5 alpha-reduced compounds are the predominant progestins contained within and secreted by the corpus luteum of the African elephant, both during the ovarian cycle and throughout pregnancy. They also provide preliminary evidence to suggest that measurements of 5 alpha-reduced metabolites may reflect corpus luteum function more closely than those of P4.
5α-还原代谢产物5α-孕烷-3,20-二酮（5α-DHP）和3α-羟基-5α-孕烷-20-酮（5α-P-3α-OH）是非洲象黄体生物合成的主要孕激素。本研究的目的是确定这些5α-还原孕激素在黄体和循环中的浓度与孕酮（P4）的关系，并研究它们的测量是否反映黄体功能。从在克鲁格国家公园被射杀的怀孕和未怀孕成年大象身上采集卵巢（黄体）组织（来自8只动物的30个黄体和3个红体）和血浆样本（30只动物）。通过高效液相色谱法纯化后，对组织和血浆提取物进行酶免疫测定，实现对5α-还原孕激素和P4的特异性免疫测量。5α-DHP和5α-P-3α-OH的平均（±标准误）黄体浓度分别为79.5±9.4微克/克和196.5±24.8微克/克，比P4的浓度（平均±标准误，0.16±0.01微克/克）高约2 - 3个数量级。与妊娠早期相比，妊娠晚期黄体中5α-还原孕激素的浓度往往较低，在红体中最低，而在所检查的所有组织/阶段中P4水平相似。在血浆中，5α-还原孕激素也比P4占优势（5α-DHP:P4和5α-P-3α-OH:P4的平均比值分别为20.3和13.4）。与黄体组织的结果相似，妊娠晚期血浆中5α-还原孕激素的浓度低于妊娠早期和未怀孕动物，而P4的浓度则不然。此外，两种5α-还原代谢产物的血浆水平与妊娠年龄呈负相关，而P4的血浆水平则不然。还在一只圈养雌性大象的两个完整卵巢周期中，每周采集血液样本测量（无需色谱法）5α-还原代谢产物的水平。两次测量均显示出周期性变化（类似于P4），黄体期升高10至15倍。结果表明，在卵巢周期和整个妊娠期，5α-还原化合物是非洲象黄体所含和分泌的主要孕激素。它们还提供了初步证据，表明测量5α-还原代谢产物可能比测量P4更能准确反映黄体功能。
