Brannian J D
Department of Obstetrics and Gynecology, University of South Dakota, School of Medicine, Sioux Falls 57105-1570, USA.
Biol Reprod. 1997 Jan;56(1):221-8. doi: 10.1095/biolreprod56.1.221.
A pathway(s) for uptake of modified (e.g., acetylated, oxidized) low-density lipoprotein (LDL) moieties has been recently discovered on luteal cells of certain species. The expression and function of this pathway during the life span of the corpus luteum (CL) have not been investigated. Aims of the present study were the following: 1) to determine whether porcine small and large luteal cells take up modified LDL; if so, 2) to compare uptake of native and modified LDL by luteal cell subpopulations during the luteal life span and 3) to compare effects of native and modified LDL on luteal steroidogenesis during the estrous cycle. Collagenase-dispersed luteal cells were prepared from porcine ovaries at various stages of the estrous cycle: early (E, Days 4-6), mid (M, Days 8-10), mid-late (ML, Day 13-14), or late (L, Day 16-17) (estrus = Day 0). Cells were incubated with fluorescent-tagged LDL (Dil-LDL; 0-10 microg/ml) or acetylated LDL (Dil-AC-LDL; 0-10 microg/ml). Fluorescence was analyzed by multiparameter flow cytometry in each of three subpopulations of cells: small (SLC) and large (LLC) luteal cells and nonsteroidogenic cells. The percentage of LLC taking up Dil-LDL remained relatively constant (65-75%) from E to ML cycle and then declined (13.3 +/- 4.1%; p < 0.05); these findings were consistent with previous data. In contrast, the percentage of LLC taking up Dil-AC-LDL gradually increased from E (29.8 +/- 8.5%) to ML (68.3 +/- 5.9%) stage and then declined (17.1 +/- 2.3%; p < 0.05). Similarly, Dil-LDL uptake by SLC was relatively constant (15-20%) from E to M cycle, declining to 2.9 +/- 0.5% at L cycle. Dil-AC-LDL uptake by SLC progressively increased from E (5.4 +/- 2.6%) to ML (24.3 +/- 6.9%) and then fell somewhat (12.9 +/- 6.7%) in L cycle. Few (< 2%) nonsteroidogenic cells labeled for Dil-LDL at all stages, whereas Dil-AC-LDL uptake by nonsteroidogenic cells was similar to that by SLC. Dual-uptake experiments revealed subtypes of LLC that took up either native LDL only or both native and modified LDL. Progesterone (P4) production by E and M luteal cell cultures was dose-dependently increased (p < 0.05) by both native and modified LDL. In contrast, modified LDL suppressed (up to 40-50%, p < 0.05) steroidogenesis by ML and L cultures, whereas LDL had no significant effect. Only native LDL stimulated P4 production by isolated SLC, although both native and modified LDL similarly increased P4 production by LLC. In conclusion, expression of one or more scavenger LDL pathways on porcine luteal cell subtypes is dynamic. Moreover, modified LDL can exert both stimulatory and inhibitory effects on luteal steroidogenesis in vitro. Differential expression and function of a scavenger LDL pathway by subpopulations of cells within the CL may play a novel role in luteal development, function, and/or regression.
最近在某些物种的黄体细胞上发现了一条摄取修饰（如乙酰化、氧化）低密度脂蛋白（LDL）部分的途径。该途径在黄体（CL）生命周期中的表达和功能尚未得到研究。本研究的目的如下：1）确定猪的小黄体细胞和大黄体细胞是否摄取修饰的LDL；如果是，2）比较黄体生命周期中黄体细胞亚群对天然LDL和修饰LDL的摄取，以及3）比较发情周期中天然LDL和修饰LDL对黄体类固醇生成的影响。从发情周期不同阶段（早期（E，第4 - 6天）、中期（M，第8 - 10天）、中后期（ML，第13 - 14天）或晚期（L，第16 - 17天）（发情期 = 第0天））的猪卵巢中制备胶原酶分散的黄体细胞。将细胞与荧光标记的LDL（Dil-LDL；0 - 10μg/ml）或乙酰化LDL（Dil-AC-LDL；0 - 10μg/ml）一起孵育。通过多参数流式细胞术分析细胞的三个亚群（小（SLC）和大（LLC）黄体细胞以及非类固醇生成细胞）中的荧光。摄取Dil-LDL的LLC百分比从E期到ML期相对保持恒定（65 - 75%），然后下降（13.3±4.1%；p < 0.05）；这些发现与先前的数据一致。相比之下，摄取Dil-AC-LDL的LLC百分比从E期（29.8±8.5%）到ML期逐渐增加（68.3±5.9%），然后下降（17.1±2.3%；p < 0.05）。同样，SLC对Dil-LDL的摄取从E期到M期相对恒定（15 - 20%），在L期降至2.9±0.5%。SLC对Dil-AC-LDL的摄取从E期（5.4±2.6%）到ML期逐渐增加（24.3±6.9%），然后在L期略有下降（12.9±6.7%）。在所有阶段，很少有（<2%）非类固醇生成细胞被标记为摄取Dil-LDL，而非类固醇生成细胞对Dil-AC-LDL的摄取与SLC相似。双重摄取实验揭示了LLC的亚型，它们要么仅摄取天然LDL，要么同时摄取天然LDL和修饰LDL。E期和M期黄体细胞培养物中孕酮（P4）的产生在天然LDL和修饰LDL作用下均呈剂量依赖性增加（p < 0.05）。相比之下，修饰LDL抑制（高达40 - 50%，p < 0.05）ML期和L期培养物的类固醇生成，而LDL无显著影响。只有天然LDL刺激分离的SLC产生P4，尽管天然LDL和修饰LDL同样增加LLC产生P4。总之，猪黄体细胞亚型上一种或多种清道夫LDL途径的表达是动态的。此外，修饰LDL在体外对黄体类固醇生成可产生刺激和抑制作用。CL内细胞亚群对清道夫LDL途径的差异表达和功能可能在黄体发育、功能和/或退化中发挥新作用。
