Knusel B, Hefti F
Dept. of Neurology, University of Miami, FL 33101.
J Neurosci Res. 1988 Oct-Dec;21(2-4):365-75. doi: 10.1002/jnr.490210228.
The well-documented role of nerve growth factor (NGF) in the function of cholinergic neurons in the mammalian basal forebrain can be regarded as a paradigm for the action of trophic substances on CNS neurons. Although several growth factors have been identified in recent years, the specificities and importance of such factors for the development of the nervous system are still unknown. In the present study it has been tested whether NGF affects the group of pedunculopontine cholinergic neurons. This population, which has been described in detail only recently, is located more caudally than but resembles, in some aspects, the basal forebrain cholinergic neurons. The cell bodies are located in the metencephalic pedunculopontine and dorsolateral tegmental nuclei. Similar to the forebrain cholinergic neurons, they are medium to large in size and ascend centrally with long axons. Projection areas are widespread throughout the mesencephalon and diencephalon. Dissociated pontine and septal cells of fetal rat brain (embryo ages E14 to E17) were grown in culture for 7 to 14 days in the presence or absence of NGF. Furthermore, a possible action of retinoic acid and ciliary neuronotrophic factor (CNTF) on cholinergic neurons of both the basal forebrain and the pontine area were tested. Differentiation of cultured cholinergic neurons was assessed by biochemical determination of choline acetyltransferase (ChAT) activity and by immunocytochemical staining for ChAT. NGF in concentrations of 1 to 1,000 ng/ml medium increased the number of immunostained cells and the staining intensity in ChAT immunocytochemistry and enhanced ChAT activity by at least 100% above control levels in septal cultures, thus confirming earlier results. In marked contrast, the same concentrations of NGF failed to influence ChAT activity or immunocytochemical staining in cultures of the pontine area. Retinoic acid (10(-8) M to 10(-5) M) and CNTF (0.2 and 2.0 ng/ml, corresponding to 1 and 10 trophic units, as defined in the ciliary ganglion cell assay) failed to enhance ChAT activity in either culture system and did not potentiate the NGF-mediated increase of ChAT activity in septal cultures. Our results, which indicate that pedunculopontine cholinergic neurons do not respond to NGF during development, are in line with those of NGF-receptor visualization studies that failed to demonstrate such receptors on cholinergic pontine cells in postnatal and adult rats. The findings further underline the specificity of NGF action in the central nervous system and, in particular, do not support the idea of transmitter-specific neurotrophic factors.(ABSTRACT TRUNCATED AT 400 WORDS)
神经生长因子（NGF）在哺乳动物基底前脑胆碱能神经元功能中所起的作用有充分的文献记载，可被视为营养物质对中枢神经系统（CNS）神经元作用的一个范例。尽管近年来已鉴定出几种生长因子，但这些因子对神经系统发育的特异性和重要性仍不清楚。在本研究中，已对NGF是否影响脚桥胆碱能神经元群进行了测试。这一神经元群直到最近才被详细描述，其位置比基底前脑胆碱能神经元更靠尾侧，但在某些方面与之相似。细胞体位于后脑的脚桥核和背外侧被盖核。与前脑胆碱能神经元相似，它们大小为中等至大型，轴突长且向中枢延伸。投射区域广泛分布于中脑和间脑。将胎鼠脑（胚胎年龄E14至E17）分离的脑桥和隔区细胞在有或无NGF的情况下培养7至14天。此外，还测试了视黄酸和睫状神经营养因子（CNTF）对基底前脑和脑桥区域胆碱能神经元的可能作用。通过生化测定胆碱乙酰转移酶（ChAT）活性以及对ChAT进行免疫细胞化学染色来评估培养的胆碱能神经元的分化。培养基中浓度为1至1000 ng/ml的NGF增加了免疫染色细胞的数量以及ChAT免疫细胞化学中的染色强度，并使隔区培养物中的ChAT活性比对照水平至少提高了100%，从而证实了早期结果。与之形成显著对比的是，相同浓度的NGF未能影响脑桥区域培养物中的ChAT活性或免疫细胞化学染色。视黄酸（10⁻⁸ M至10⁻⁵ M）和CNTF（0.2和2.0 ng/ml，对应于睫状神经节细胞测定中定义的1和10个营养单位）在任一培养系统中均未能增强ChAT活性，也未增强隔区培养物中NGF介导的ChAT活性增加。我们的结果表明，脚桥胆碱能神经元在发育过程中对NGF无反应，这与NGF受体可视化研究的结果一致，该研究未能在出生后和成年大鼠的胆碱能脑桥细胞上证明此类受体的存在。这些发现进一步强调了NGF在中枢神经系统中作用的特异性，特别是不支持递质特异性神经营养因子的观点。（摘要截短于400字）
