Rao M S, Tyrrell S, Landis S C, Patterson P H
Division of Biology, California Institute of Technology, Pasadena 91125.
Dev Biol. 1992 Apr;150(2):281-93. doi: 10.1016/0012-1606(92)90242-9.
We examined the effects of ciliary neurotrophic factor (CNTF) and depolarization, two environmental signals that influence noradrenergic and cholinergic function, on neuropeptide expression by cultured sympathetic neurons. Sciatic nerve extract, a rich source of CNTF, increased levels of vasoactive intestinal peptide (VIP), substance P, and somatostatin severalfold while significantly reducing levels of neuropeptide Y (NPY). No change was observed in the levels of leu-enkephalin (L-Enk). These effects were abolished by immunoprecipitation of CNTF-like molecules from the extract with an antiserum raised against recombinant CNTF, and recombinant CNTF caused changes in neuropeptide levels similar to those of sciatic nerve extract. Alterations in neuropeptide levels by CNTF were dose-dependent, with maximal induction at concentrations of 5-25 ng/ml. Peptide levels were altered after only 3 days of CNTF exposure and continued to change for 14 days. Depolarization of sympathetic neuron cultures with elevated potassium elicited a different spectrum of effects; it increased VIP and NPY content but did not alter substance P, somatostatin, or L-Enk. Depolarization is known to block cholinergic induction in response to heart cell conditioned medium and we found that it blocked the induction of choline acetyltransferase (ChAT) and peptides by recombinant cholinergic differentiation factor/leukemia inhibitory factor (CDF/LIF). In contrast, it did not antagonize the effects of CNTF on either ChAT activity or neuropeptide expression. Thus, while CNTF has effects on neurotransmitter properties similar to those previously reported for CDF/LIF, the actions of these two factors are differentially modulated by depolarization, suggesting that the mechanisms of cholinergic and neuropeptide induction for the two factors differ. In addition, in contrast to CDF/LIF, CNTF did not alter levels of ChAT, VIP, substance P, or somatostatin in cultured dorsal root ganglion neurons. These observations indicate that CNTF and depolarization affect the expression of neuropeptides by sympathetic neurons and provide evidence for an overlapping yet distinct spectrum of actions of the two neuronal differentiation factors, CNTF and CDF/LIF.
我们研究了睫状神经营养因子（CNTF）和去极化这两种影响去甲肾上腺素能和胆碱能功能的环境信号对培养的交感神经元神经肽表达的影响。坐骨神经提取物是CNTF的丰富来源，它使血管活性肠肽（VIP）、P物质和生长抑素的水平增加了几倍，同时显著降低了神经肽Y（NPY）的水平。亮脑啡肽（L-Enk）的水平未观察到变化。用针对重组CNTF产生的抗血清对提取物中的CNTF样分子进行免疫沉淀后，这些作用被消除，并且重组CNTF引起的神经肽水平变化与坐骨神经提取物相似。CNTF引起的神经肽水平变化呈剂量依赖性，在5 - 25 ng/ml浓度时诱导作用最大。仅在暴露于CNTF 3天后肽水平就发生了改变，并持续变化14天。用升高的钾使交感神经元培养物去极化引发了不同的效应谱；它增加了VIP和NPY的含量，但不改变P物质、生长抑素或L-Enk。已知去极化会阻断对心脏细胞条件培养基的胆碱能诱导，并且我们发现它会阻断重组胆碱能分化因子/白血病抑制因子（CDF/LIF）对胆碱乙酰转移酶（ChAT）和肽的诱导。相反，它并不拮抗CNTF对ChAT活性或神经肽表达的作用。因此，虽然CNTF对神经递质特性的作用与先前报道的CDF/LIF相似，但这两种因子的作用受到去极化的差异调节，表明这两种因子的胆碱能和神经肽诱导机制不同。此外，与CDF/LIF不同，CNTF不会改变培养的背根神经节神经元中ChAT、VIP、P物质或生长抑素的水平。这些观察结果表明，CNTF和去极化影响交感神经元神经肽的表达，并为两种神经元分化因子CNTF和CDF/LIF重叠但又不同的作用谱提供了证据。
