Louis J C, Magal E, Burnham P, Varon S
Department of Biology 0601, University of California, San Diego, La Jolla 92093.
Dev Biol. 1993 Jan;155(1):1-13. doi: 10.1006/dbio.1993.1001.
Ciliary neurotrophic factor (CNTF) was found to promote the expression of tyrosine hydroxylase (TH) immunoreactivity by cultured noradrenergic neurons from the locus coeruleus (LC) of E18 rat fetuses, but only in the concomitant presence of norepinephrine (NE), their own neurotransmitter. The number of TH-positive cells in LC cultures was shown to decrease by 65% within 3 days and by 75% after 6 days. Treatment with 10 TU/ml human recombinant CNTF together with 1 microM NE was able to fully maintain the initial number of TH-positive neurons for 3 days. This effect, however, was no longer seen after 6 days of continuous exposure. A 24-hr treatment with CNTF/NE was capable of completely restoring the initial number of TH-positive cells, even if its addition was delayed for 2 days. Moreover, when its addition was delayed for 5 days, CNTF/NE restored approximately 80% of the TH-positive neurons that were initially present. These results suggest that the disappearance of TH-positive neurons in LC cultures is not due to their death, but rather to the reduced expression of TH and that the simultaneous exposure to CNTF and NE upregulates TH. Effects on TH-positive cell number were not evoked by CNTF or NE alone. The CNTF/NE effect was dependent on protein synthesis, but was only partially inhibited by RNA synthesis inhibitors, suggesting that both transcription from preexisting mRNA and synthesis of new RNA were stimulated. The effect of CNTF/NE was mediated by alpha 2-adrenoceptors, since it was blocked by alpha 2-antagonists and since alpha 2-agonists were able to substitute for NE. Our results suggest a novel mechanism of regulation of the phenotype of the noradrenergic LC neuron, involving the collaborative influences of CNTF and norepinephrine, their own neurotransmitter.
睫状神经营养因子（CNTF）被发现可促进来自E18大鼠胎儿蓝斑（LC）的培养去甲肾上腺素能神经元中酪氨酸羟化酶（TH）免疫反应性的表达，但仅在其自身神经递质去甲肾上腺素（NE）同时存在的情况下。LC培养物中TH阳性细胞的数量在3天内减少了65%，6天后减少了75%。用10 TU/ml人重组CNTF与1 microM NE一起处理能够在3天内完全维持TH阳性神经元的初始数量。然而，持续暴露6天后这种效果不再出现。用CNTF/NE处理24小时能够完全恢复TH阳性细胞的初始数量，即使其添加延迟2天。此外，当添加延迟5天时，CNTF/NE恢复了最初存在的约80%的TH阳性神经元。这些结果表明，LC培养物中TH阳性神经元的消失不是由于它们的死亡，而是由于TH表达的降低，并且同时暴露于CNTF和NE会上调TH。单独的CNTF或NE不会引起对TH阳性细胞数量的影响。CNTF/NE的作用依赖于蛋白质合成，但仅被RNA合成抑制剂部分抑制，这表明预先存在的mRNA的转录和新RNA的合成均受到刺激。CNTF/NE的作用是由α2 - 肾上腺素能受体介导的，因为它被α2拮抗剂阻断，并且α2激动剂能够替代NE。我们的结果提示了一种去甲肾上腺素能LC神经元表型调节的新机制，涉及CNTF和去甲肾上腺素（它们自身的神经递质）的协同影响。
