体外培养条件下钾离子对少突胶质细胞表达MBP的影响

应用体外培养、免疫细胞化学和计算机辅助图象分析方法研究了少突胶质细胞表达髓鞘碱性蛋白及高钾离子（３０ｍｍｏｌ／Ｌ）对少突胶质细胞表达髓鞘碱性蛋白的影响。结果表明，体外培养条件下，少突胶质细胞最早表达髓鞘碱性蛋白是在培养第７天。髓鞘碱性蛋白阳性的少突胶质细胞可分为大、中、小和双核四种类型，它们的构成比随培养时间延长呈动态变化。高Ｋ＋不影响少突胶质细胞表达髓鞘碱性蛋白。实验结果提示，体外培养条件下，少突胶质细胞仍能正常表达髓鞘碱性蛋白，且表达时程并不依赖神经元的存在；细胞外Ｋ＋浓度升高对髓鞘碱性蛋白在少突胶质细胞内的正常合成及表达过程无明显影响。本文对少突胶质细胞表达髓鞘碱性蛋白后的体积变化与其与中枢神经系统髓鞘形成的关系进行了讨论。

INVESTIGATION ON THE INFLUENCE OF POTASSIUM ON OLIGODENDROCYTES EXPRESSING MYELIN BASIC PROTEIN IN VITRO

The Myelin basic protein (BMP) plays an important role in myelination in central nervous system (CNS). which should be expressed in oligodendrocyte (oligo) one or two days before myelination. It has been confirmed that some substances, for example. hydrocortisone, triiodothyronine, transferrin and insulin, etc, can influence the expression of MBP in oligo. In order to investigate whether the potassium ion(K+) which is one of the important electrolytes in CNS influences oligo expressing MBP in vitro, we used the techniques of tissue culture, immunocytochemistry and computer-assisted morphometric analysis in the experiment. The optic nerves taken from P-7 Wistar rats were explanted on collagen coated coverslips, then incorporated into a Maximow assembly and sealed with paraffin. The medium of control group was composed of equal parts of DMEM, fetal bovine serum, Tyrode's BSS and chicken embryo extract, which contained about 10 mmol/L K+. In test group, the ingredient of the medium is the same as control group, hut the concentration of K+ was increased to 30 mmol/L.All cultures were maintained at 36.5C, and the medium was changed every three days. Some cultures ere fixed and then stained immunocytochemically with the antibody of MBP (PAP method). The results showed that the earliest time of expressing MBP in oligos were 7 days in vitro (div). The oligos of positive MBP could be divided into four groups (the large,the middle, the small and the double nuclei). the percentage of which was varied with the time in vitro. High concentration of K+ did not influence the expression of MBP in oligo. From the experimental results it can be seen that under the condition in vitro, oligo can also express MBP, the course of which was not dependent on the existence of neurons; and enhancing the concentration of extracellular K+ did not obviously influence the normal syntheses and expressions of MBP in oligos. It could be supposed that the double nuclei and large oligos were not mature; and the middle oligos were most active in the period of myelination in CNS, during which it was possible they secreted some materials and/or depleted part components, while decreased in volume, so, the small oligos were aged or degenerated.