Reich E E, Zackert W E, Brame C J, Chen Y, Roberts L J, Hachey D L, Montine T J, Morrow J D
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6602, USA.
Biochemistry. 2000 Mar 7;39(9):2376-83. doi: 10.1021/bi992000l.
Free radical-mediated oxidant injury and lipid peroxidation have been implicated in a number of neural disorders. We have reported that bioactive prostaglandin D2/E2-like compounds, termed D2/E2-isoprostanes, are produced in vivo by the free radical-catalyzed peroxidation of arachidonic acid. Docosahexaenoic acid, in contrast to arachidonic acid, is the most abundant unsaturated fatty acid in brain. We therefore questioned whether D/E-isoprostane-like compounds (D4/E4-neuroprostanes) are formed from the oxidation of docosahexaenoic acid. Levels of putative D4/E4-neuroprostanes increased 380-fold after oxidation of docosahexaenoic acid in vitro from 15.2 +/- 6.3 to 5773 +/- 1024 ng/mg of docosahexaenoic acid. Subsequently, chemical approaches and liquid chromatography electrospray ionization tandem mass spectrometry definitively identified these compounds as D4/E4-neuroprostanes. We then explored the formation of D4/E4-neuroprostanes from a biological source, rat brain synaptosomes. Basal levels of D4/E4-neuroprostanes were 3.8 +/- 0.6 ng/mg of protein and increased 54-fold after oxidation (n = 4). We also detected these compounds in fresh brain tissue from rats at levels of 12.1 +/- 2.4 ng/g of brain tissue (n = 3) and in human brain tissue at levels of 9.2 +/- 4.1 ng/g of brain tissue (n = 4). Thus, these studies have identified novel D/E-ring isoprostane-like compounds that are derived from docosahexaenoic acid and that are formed in brain in vivo. The fact that they are readily detectable suggests that ongoing oxidative stress is present in the central nervous system of humans and animals. Further, identification of these compounds provides a rationale for examining their role in neurological disorders associated with oxidant stress.
自由基介导的氧化损伤和脂质过氧化与多种神经疾病有关。我们曾报道，生物活性前列腺素D2/E2样化合物，即D2/E2-异前列腺素，是体内花生四烯酸自由基催化过氧化反应的产物。与花生四烯酸不同，二十二碳六烯酸是大脑中含量最丰富的不饱和脂肪酸。因此，我们质疑是否会由二十二碳六烯酸氧化形成D/E-异前列腺素样化合物（D4/E4-神经前列腺素）。体外将二十二碳六烯酸氧化后，假定的D4/E4-神经前列腺素水平从15.2±6.3 ng/mg二十二碳六烯酸增加到5773±1024 ng/mg二十二碳六烯酸，增长了380倍。随后，通过化学方法和液相色谱电喷雾电离串联质谱法明确鉴定出这些化合物为D4/E4-神经前列腺素。接着，我们探究了大鼠脑突触体这一生物来源中D4/E4-神经前列腺素的形成。D4/E4-神经前列腺素的基础水平为3.8±0.6 ng/mg蛋白质，氧化后增加了54倍（n = 4）。我们还在大鼠新鲜脑组织中检测到这些化合物，含量为12.1±2.4 ng/g脑组织（n = 3），在人类脑组织中的含量为9.2±4.1 ng/g脑组织（n = 4）。因此，这些研究鉴定出了新型的D/E环异前列腺素样化合物，它们源自二十二碳六烯酸且在体内大脑中形成。它们易于检测这一事实表明，人类和动物的中枢神经系统中存在持续的氧化应激。此外，这些化合物的鉴定为研究它们在与氧化应激相关的神经疾病中的作用提供了理论依据。
