Differential Effects of Nerve Growth Factor on Expression of Choline Acetyltransferase and Sodium‐Coupled Choline Transport in Basal Forebrain Cholinergic Neurons in Culture
Differential Effects of Nerve Growth Factor on Expression of Choline Acetyltransferase and Sodium‐Coupled Choline Transport in Basal Forebrain Cholinergic Neurons in Culture
复制标题
神经生长因子对培养的基底前脑胆碱能神经元胆碱乙酰转移酶表达和钠偶联胆碱转运的不同影响
作者：
J. Pongrac;R. Rylett
摘要：神经生长因子 (NGF) 对胚胎 17 天大鼠基底前脑原代培养物的处理差异改变了胆碱乙酰转移酶 (ChAT) 的活性和高亲和力胆碱转运；在 NGF 存在下生长 4 至 8 天的神经元中，ChAT 比活性增加了三倍，而高亲和力胆碱转运活性相对于对照没有变化。剂量反应研究表明，低浓度的 NGF 会增强神经元 ChAT 活性，EC50 为 7 ng/ml，而在 NGF 浓度高达 100 ng/ml 时，没有观察到高亲和力胆碱转运的增强。此外，与对照组相比，在 NGF 存在下生长长达 6 天的神经元中乙酰胆碱 (ACh) 的合成和 ACh 含量显着增加。这些结果表明，基底前脑神经元原代培养物中 ACh 合成的调节不受高亲和力胆碱转运系统提供胆碱的限制，并且在 NGF 存在的情况下增加 ChAT 活性而不伴随高亲和力胆碱转运的增加足以增加 ACh 合成。这进一步表明，细胞内胆碱池通常不作为乙酰胆碱合成的底物，但在 NGF 存在的情况下可能可用于乙酰胆碱合成。
Abstract: Nerve growth factor (NGF) treatment of primary cultures of embryonic day 17 rat basal forebrain differentially altered activity of choline acetyltransferase (ChAT) and high‐affinity choline transport; ChAT specific activity was increased by threefold in neurons grown in the presence of NGF for between 4 and 8 days, whereas high‐affinity choline transport activity was not changed relative to control. Dose‐response studies revealed that enhancement of neuronal ChAT activity occurred at low concentrations of NGF with an EC50 of 7 ng/ml, with no enhancement of high‐affinity choline transport observed at NGF concentrations up to 100 ng/ml. In addition, synthesis of acetylcholine (ACh) and ACh content in neurons grown in the presence of NGF for up to 6 days was increased significantly compared with controls. These results suggest that regulation of ACh synthesis in primary cultures of basal forebrain neurons is not limited by provision of choline by the high‐affinity choline transport system and that increased ChAT activity in the presence of NGF without a concomitant increase in high‐affinity choline transport is sufficient to increase ACh synthesis. This further suggests that intracellular pools of choline, which do not normally serve as substrate for ACh synthesis, may be made available for ACh synthesis in the presence of NGF.