AXON-MYELIN TRANSFER OF GLYCEROL-LABELED LIPIDS AND INORGANIC-PHOSPHATE DURING AXONAL-TRANSPORT
AXON-MYELIN TRANSFER OF GLYCEROL-LABELED LIPIDS AND INORGANIC-PHOSPHATE DURING AXONAL-TRANSPORT
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DOI：
10.1016/0006-8993(83)90136-1
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发表时间：
1983-01-01
期刊：
影响因子：
2.9
通讯作者：
HALEY, JE
中科院分区：
文献类型：
--
作者：
LEDEEN, RW;HALEY, JE
用眼内注射[~(32)P]正磷酸盐、[~(14)C]甘油和[~3H]甘油的方法，研究了兔视神经系统中脂质和脂质前体的轴突到髓鞘的转移。胆碱、乙醇胺、磷酸甘油酯和髓鞘在注射后7-21天内[~(32)P]-放射性升高，[~(14)C]和[~(32)P]-放射性相对恒定。在同一时期，所有轴突和轴膜富集区的后一种放射性都降低了。这些发现支持这一概念，即一部分经历轴突运输的物质通过两种机制进入髓磷脂池：完整脂质的跨细胞转移和前体的轴突-髓鞘转移，这些前体被髓鞘定位的酶重新用于脂质的生物合成。这项研究表明，PI可能是由轴突内的分解代谢活动产生的，能够进入髓鞘并参与前面描述的丝氨酸、胆碱和酰基链的再利用机制。~3H/~(14)C比值的相对恒定表明，大部分甘油不是以这种方式重新利用的，而可能是通过转移完整的脂质进入髓鞘的。这些和早期的结果表明，髓鞘对轴突营养物质的代谢依赖可能是一种形式。
Axon-to-myelin transfer of lipids and lipid precursors was studied in the rabbit optic system by intraocular injection of [32P]orthophosphate, [14C]glycerol and [3H]glycerol. Choline and ethanolamine phosphoglycerides and myelin showed increasing [32P]-radioactivity between 7-21 days following injection; [3H]- and [14C]-radioactivities remained relatively constant. The latter radioactivities decreased in all the axon- and axolemma-enriched fractions during the same period. These findings support the concept that a portion of substances undergoing axonal transport enters the pool of myelin lipids by 2 mechanisms: transcellular transfer of intact lipid and axon-myelin transfer of precursors which are reutilized for lipid biosynthesis by myelin-localized enzymes. This study shows that Pi, possibly generated by catabolic activity within the axon, is able to enter myelin and participate in the reutilization mechanism as previously described for serine, choline and acyl chains. The relative invariance of the 3H:14C ratio suggested that the majority of glycerol is not reutilized in this manner but probably entered myelin through transfer of intact lipid. These and earlier results suggest a possible form of metabolic dependence of myelin on trophic substances from the axon.