神经生长因子对体外培养的大鼠颈上节神经突起生长及RNA和DNA合成的作用的放射自显影研究

神经生长因子(NGF)可促进靶神经节神经突起生长晕的生长。本文应用~3H-尿嘧啶核苷和~3H-腺胸嘧啶核苷放射自显影术进一步探讨此作用与神经元合成RNA和DNA的关系。实验材料用新生大鼠颈上节。按Maximow双盖片法进行培养。培养物分NGF组(培养液内添加NGF粗制剂)和对照组(不用CNGF),培养终止前分别转入含放射性同位素的培养液中孵育,然后取出固定、连续切片、制作自显影标本进行观察。实验结果指出:NGF组培养物被~3H-尿嘧啶核苷标记的神经元百分率及标记颗粒水平均高于对照组,而且每当培养物神经突起生长晕生长速度出现高峰的前夕,神经元~3H-尿嘧啶核苷标记颗粒水平都是明显地增高。这说明NGF可促进颈上节神经元的RNA合成,后者与神经突起的迅速生长有一定的相互关系。在~3H-胸腺嘧啶核苷标记培养物神经元的实验中,观察到NGF可促进培养第3天的颈上节少量的神经元合成DNA。

Effects of Nerve Growth Factor on Neurite Outgrowth and on Synthesis of RNA and DNA in Rat Superior Cervical Ganglia in Vitro: An Autoradiographic Study

Nerve growth factor (NGF) can promote the outgrowth of neurites of the target ganglia. In order to further explore the relationship between this effect and the synthesis of RNA and DNA in the neurons, an autoradiography of 3H-uridine and 3H-thymidine was used. Superior cervical ganglia (SCG) from newborn rats were used for the material of experiments and cultivated by Maximow's double coverslip method. All cultures were divided into a group of NGF (a crude preparation of NGF was added to the medium) and another group served as control (no NGF was added to the medium). Before tissue culture was stopped, the coverslip cultures were transferred to Petri dishes containing the labeling-medium and incubated, and then taken out to be fixated, to be made into serial sections and autoradiographic specimens, which were analysed under the light microscope. The results show that the percentage and the level of grains of neurons uabeled by 3H-uridine in a group of NGF are higher than that of control. Moreover, before the growth rate of neurites shows a peak, the level of grains of neurons labeled by 3H-uridine in a group of NGF is obviously increased. Hence, this evidence suggests that NGF can promote the synthesis of RNA in neurons of SCG, which has a direct bearing on the quick outgrowth of neurites. In the experiments with 3H-thymidine incorporation, that the NGF may promote the synthesis of DNA in some neurons of the third day SCG in vitro was also observed.