Auld D S, Mennicken F, Day J C, Quirion R
Douglas Hospital Research Centre, Montréal, Canada.
J Neurochem. 2001 Apr;77(1):253-62. doi: 10.1046/j.1471-4159.2001.t01-1-00234.x.
Several lines of evidence indicate that nerve growth factor is important for the development and maintenance of the basal forebrain cholinergic phenotype. In the present study, using rat primary embryonic basal forebrain cultures, we demonstrate the differential regulation of functional cholinergic markers by nerve growth factor treatment (24--96 h). Following a 96-h treatment, nerve growth factor (1--100 ng/mL) increased choline acetyltransferase activity (168--339% of control), acetylcholine content (141--185%), as well as constitutive (148--283%) and K(+)-stimulated (162--399%) acetylcholine release, but increased release was not accompanied by increased high-affinity choline uptake. Enhancement of ACh release was attenuated by vesamicol (1 microM), suggesting a vesicular source, and was abolished under choline-free conditions, emphasizing the importance of extracellular choline as the primary source for acetylcholine synthesized for release. A greater proportion of acetylcholine released from nerve growth factor-treated cultures than from nerve growth factor-naïve cultures was blocked by voltage-gated Ca(2+) channel antagonists, suggesting that nerve growth factor modified this parameter of neurotransmitter release. Cotreatment of NGF (20 ng/mL) with K252a (200 nM) abolished increases in ChAT activity and prevented enhancement of K(+)-stimulated ACh release beyond the level associated with K252a, suggesting the involvement of TrkA receptor signaling. Also, neurotrophin-3, neurotrophin-4 and brain-derived neurotrophic factor (all at 5--200 ng/mL) increased acetylcholine release, although they were not as potent as nerve growth factor and higher concentrations were required. High brain-derived neurotrophic factor concentrations (100 and 200 ng/mL) did, however, increase release to a level similar to nerve growth factor. In summary, long-term exposure (days) of basal forebrain cholinergic neurons to nerve growth factor, and in a less-potent fashion the other neurotrophins, enhanced the release of acetylcholine, which was dependent upon a vesicular pool and the availability of extracellular choline.
多条证据表明，神经生长因子对于基底前脑胆碱能表型的发育和维持至关重要。在本研究中，我们使用大鼠原代胚胎基底前脑培养物，证明了神经生长因子处理（24 - 96小时）对功能性胆碱能标志物的差异调节作用。经过96小时的处理后，神经生长因子（1 - 100 ng/mL）增加了胆碱乙酰转移酶活性（对照的168 - 339%）、乙酰胆碱含量（141 - 185%），以及组成性（148 - 283%）和钾离子刺激的（162 - 399%）乙酰胆碱释放，但释放增加并未伴随着高亲和力胆碱摄取的增加。水泡性口炎病毒糖蛋白（1 microM）减弱了乙酰胆碱释放的增强，表明其来源于囊泡，并且在无胆碱条件下被消除，这强调了细胞外胆碱作为合成用于释放的乙酰胆碱的主要来源的重要性。与未用神经生长因子处理的培养物相比，从用神经生长因子处理的培养物中释放的乙酰胆碱有更大比例被电压门控钙通道拮抗剂阻断，这表明神经生长因子改变了神经递质释放的这一参数。将神经生长因子（20 ng/mL）与K252a（200 nM）共同处理可消除胆碱乙酰转移酶活性的增加，并阻止钾离子刺激的乙酰胆碱释放增强至超过与K252a相关的水平，这表明TrkA受体信号传导参与其中。此外，神经营养因子-3、神经营养因子-4和脑源性神经营养因子（均为5 - 200 ng/mL）增加了乙酰胆碱释放，尽管它们的效力不如神经生长因子，且需要更高浓度。然而，高浓度的脑源性神经营养因子（100和200 ng/mL）确实将释放增加到了与神经生长因子相似的水平。总之，基底前脑胆碱能神经元长期（数天）暴露于神经生长因子以及以较弱的方式暴露于其他神经营养因子，增强了乙酰胆碱的释放，这依赖于囊泡池和细胞外胆碱的可用性。
