Zelinski M B, Selivonchick D P, Stormshak F
Department of Animal Science, Oregon State University, Corvallis 97331-6702.
Biol Reprod. 1988 May;38(4):768-79. doi: 10.1095/biolreprod38.4.768.
Lipid composition of plasma membranes from luteal cells was examined to determine whether changes in this organelle occur during regression and maintenance of the corpus luteum in nonpregnant (NP) and pregnant (P) ewes, respectively. Forty ewes were assigned to be killed on Day 13 or 15 of the estrous cycle (D13-NP and D15-NP) or pregnancy (D13-P and D15-P). Purification of luteal plasma membranes on discontinuous sucrose gradients yielded two fractions, designated F1 and F2, that exhibited the greatest enrichment of 5'-nucleotidase activity (five- and fourfold, respectively) over that of the homogenate. These fractions also yielded the lowest contamination by endoplasmic reticulum as represented by nicotinamide adenine dinucleotide phosphate (NADPH) cytochrome C reductase activity and mitochondrial membranes as indicated by succinate dehydrogenase activity. Predominant phospholipids identified in membranes obtained from all groups were phosphatidylcholine (PC, 48.9 +/- 0.6% of total phospholipid), phosphatidylethanolamine (PE, 33.3 +/- 0.4%), sphingomyelin (SPH, 9.7 +/- 0.3%), phosphatidylserine (PS, 3.5 +/- 0.2%), and phosphatidylinositol (PI, 4.0 +/- 0.5%). No changes in microgram phospholipid/mg membrane protein were observed for any luteal phospholipid on D13 and 15 of the estrous cycle or pregnancy. No significant changes in the relative percentages of major fatty acids present in PC (palmitic [16:0], oleic [18:1]), PE (stearic [18:0], 18:1 and arachidonic [20:4]), or PS (18:0, 18:1, docosatetraenoic [22:4]), nor in the ratios of unsaturated (U) to saturated (S) fatty acids in these phospholipids were observed. Significant differences in unsaturated fatty acids of chain length greater than 20 carbons present in minor quantities in PC, PE, and PS were detected between NP and P ewes as well as between days within reproductive stage. The profile of major fatty acids present in PI revealed decreases in 18:0 and 20:4 in D15-NP and increases in 22:4 and docosapentaenoic acid (22:5) in luteal membranes of both D13- and D15-NP ewes relative to the levels of these fatty acids in PI of corresponding groups of pregnant ewes. There was a general trend for 20:4 levels of PC and PI in membranes of D15-NP ewes to be inversely related to those of D15-P ewes. Collectively, these changes were reflected by an increased U:S fatty acid ratio in luteal membrane PI during the estrous cycle. Specific binding of [125I] iodo-human chorionic gonadotropin to luteal plasma membranes from NP and P ewes on D13 and 15 (6/group) revealed similar affinities and concentrations of unoccupied luteinizing hormone (LH) receptors.(ABSTRACT TRUNCATED AT 400 WORDS)
研究黄体细胞的质膜脂质组成，以确定在未孕（NP）和怀孕（P）母羊的黄体退化和维持过程中，该细胞器是否发生变化。40只母羊被分配在发情周期的第13天或第15天（D13-NP和D15-NP）或怀孕期（D13-P和D15-P）处死。通过不连续蔗糖梯度纯化黄体质膜得到两个组分，命名为F1和F2，它们相对于匀浆，5'-核苷酸酶活性的富集程度最高（分别为5倍和4倍）。这些组分中，以内质网的烟酰胺腺嘌呤二核苷酸磷酸（NADPH）细胞色素C还原酶活性表示的内质网污染以及以琥珀酸脱氢酶活性表示的线粒体膜污染也是最低的。在所有组获得的膜中鉴定出的主要磷脂为磷脂酰胆碱（PC，占总磷脂的48.9±0.6%）、磷脂酰乙醇胺（PE，33.3±0.4%）、鞘磷脂（SPH，9.7±0.3%）、磷脂酰丝氨酸（PS，3.5±0.2%）和磷脂酰肌醇（PI，4.0±0.5%）。在发情周期或怀孕期的第13天和第15天，未观察到任何黄体磷脂的微克磷脂/毫克膜蛋白有变化。在PC（棕榈酸[16:0]、油酸[18:1]）、PE（硬脂酸[18:0]、18:1和花生四烯酸[20:4]）或PS（18:0、18:1、二十二碳四烯酸[22:4]）中存在的主要脂肪酸的相对百分比，以及这些磷脂中不饱和（U）与饱和（S）脂肪酸的比例均未观察到显著变化。在NP和P母羊之间以及生殖阶段内不同天数之间，检测到PC、PE和PS中少量存在的链长大于20个碳的不饱和脂肪酸存在显著差异。PI中存在的主要脂肪酸谱显示，相对于相应怀孕母羊组PI中的这些脂肪酸水平，D15-NP母羊黄体膜中18:0和20:4减少，D13-和D15-NP母羊黄体膜中22:4和二十二碳五烯酸（22:5）增加。D15-NP母羊膜中PC和PI的20:4水平总体上与D15-P母羊的呈负相关。总的来说，这些变化反映为发情周期中黄体膜PI的U:S脂肪酸比值增加。[125I]碘人绒毛膜促性腺激素与D13和15天的NP和P母羊黄体质膜的特异性结合（每组6只）显示，未占据的促黄体生成素（LH）受体具有相似的亲和力和浓度。（摘要截断于400字）
