放射性脂肪酸和葡萄糖的放射性衍生物掺入大脑皮质突触下组分的磷脂中。

The incorporation of radioactive fatty acids and of radioactive derivatives of glucose into the phospholipids of subsynaptosomal fractions of cerebral cortex.

作者信息

Baker R, Dowdall M J, Whittaker V P

出版信息

Biochem J. 1976 Jan 15;154(1):65-75. doi: 10.1042/bj1540065.

DOI:10.1042/bj1540065

PMID:179537

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1172677/

Abstract

Crude synaptosomal fractions (P2) from guinea-pig cerebral cortex were incubated in a Krebs-glucose medium containing labelled fatty acids and [3H]glucose. After the shortest incubation period (7.5 min) a high percentage (50-80%) of the total radioactive fatty acids was found in the P2 fractions. 2. After the incubation, the synaptosomal fractions were submitted to hypo-osmotic disruption and subsynaptosomal fractionation was carried out by using discontinuous-sucrose-gradient centrifugation. The specific radioactivities of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol were determined in fractions D (synaptic vesicles), E (microsomal preparation) and H (disrupted synaptosomes), as were the specific activities of a number of marker enzymes and the distribution of acetylcholine. 3. By using [14C]oleate, [14C]arachidonate, [3H]palmitate and [3H]glucose, the order to specific radioactivities in fraction D was found to be: phosphatidylinositol greater than phosphatidylcholine greater than phosphatidylserine greater than phosphatidylethanolamine. 4. The specific radioactivities of phosphatidylcholine and phosphatidylethanolamine were always higher in fraction D than in fraction E. As fraction E had higher specific activities of several membrane marker enzymes, the enhanced labelling found in fraction D was considered to be localized in the synaptic vesicles. In this fraction, phosphatidylinositol made particularly large contributions to the total phospholipid labelling derived from [14C]arachidonate and [3H]glucose. 5. The similar labelling ratios of fatty acid/glucose in the phospholipids of fractions D and E, and the high specific radioactivities in the total phospholipid of the soluble fraction O, suggested intrasynaptosomal phospholipid transport.

摘要

将豚鼠大脑皮层的粗制突触体组分（P2）在含有标记脂肪酸和[3H]葡萄糖的Krebs-葡萄糖培养基中孵育。在最短孵育期（7.5分钟）后，在P2组分中发现总放射性脂肪酸的高百分比（50 - 80%）。2. 孵育后，对突触体组分进行低渗破坏，并通过不连续蔗糖梯度离心进行亚突触体分级分离。测定了D组分（突触小泡）、E组分（微粒体制备物）和H组分（破碎的突触体）中磷脂酰胆碱、磷脂酰乙醇胺、磷脂酰丝氨酸和磷脂酰肌醇的比放射性，以及一些标记酶的比活性和乙酰胆碱的分布。3. 通过使用[14C]油酸、[14C]花生四烯酸、[3H]棕榈酸和[3H]葡萄糖，发现D组分中比放射性的顺序为：磷脂酰肌醇＞磷脂酰胆碱＞磷脂酰丝氨酸＞磷脂酰乙醇胺。4. D组分中磷脂酰胆碱和磷脂酰乙醇胺的比放射性总是高于E组分。由于E组分具有几种膜标记酶的较高比活性，D组分中发现的增强标记被认为定位于突触小泡。在该组分中，磷脂酰肌醇对源自[14C]花生四烯酸和[3H]葡萄糖的总磷脂标记贡献特别大。5. D组分和E组分磷脂中脂肪酸/葡萄糖的相似标记率，以及可溶性组分O总磷脂中的高比放射性，提示突触体内磷脂转运。