Rosenberg M, Pié B, Cooper E
Department of Physiology, McGill University, Montréal, Québec, Canada H3G 1Y6.
J Neurosci. 1997 Sep 1;17(17):6629-38. doi: 10.1523/JNEUROSCI.17-17-06629.1997.
Serotonin 5-HT3 receptors (5-HT3Rs) are ligand-gated ion channels expressed by many peripheral neurons and are involved in several physiological processes. To learn more about the developmental regulation of 5-HT3R expression, we investigated rat sympathetic and vagal sensory neurons. We found that sympathetic and sensory neurons differ in their regulation of 5-HT3R expression during early postnatal life and as these neurons develop in culture. In SCG neurons 5-HT3R transcript levels are low at postnatal day 1 (P1) and increase 7.5-fold by P21; this increase occurs even after elimination of preganglionic innervation. In comparison, 5-HT3R mRNA levels in P1 nodose neurons are over 14-fold greater than in P1 SCG and change little by P21. We show that 5-HT3R transcript levels in nodose neurons depend on intact target innervation and drop by 60% after axotomy. When P1 SCG neurons develop in culture, we observed a significant increase in 5-HT3R expression: after 7 d in culture, transcript levels increase ninefold versus a threefold increase for neurons developing for 7 d in vivo. In contrast, 5-HT3R mRNA levels in cultured nodose neurons drop by 70% within 24 hr; however, this drop is transient. After 2 d, transcript levels begin to increase, and after 7 d, they are above initial values. We show that this delayed increase in 5-HT3R expression depends on neurotrophins. In both nodose and sympathetic neurons we found that the changes in 5-HT3R gene expression correlate directly with the appearance of 5-HT-evoked current densities.
血清素5-HT3受体（5-HT3Rs）是由许多外周神经元表达的配体门控离子通道，参与多种生理过程。为了更多地了解5-HT3R表达的发育调控，我们研究了大鼠交感神经和迷走感觉神经元。我们发现，交感神经和感觉神经元在出生后早期以及在培养中发育时，其5-HT3R表达的调控存在差异。在颈上神经节（SCG）神经元中，5-HT3R转录水平在出生后第1天（P1）较低，到P21时增加7.5倍；即使在去除节前神经支配后，这种增加仍会发生。相比之下，P1结状神经元中的5-HT3R mRNA水平比P1 SCG中的高14倍以上，到P21时变化不大。我们表明，结状神经元中的5-HT3R转录水平依赖于完整的靶神经支配，轴突切断后会下降60%。当P1 SCG神经元在培养中发育时，我们观察到5-HT3R表达显著增加：培养7天后，转录水平增加9倍，而在体内发育7天的神经元转录水平仅增加3倍。相反，培养的结状神经元中的5-HT3R mRNA水平在24小时内下降70%；然而，这种下降是短暂的。2天后，转录水平开始增加，7天后，它们高于初始值。我们表明，5-HT3R表达的这种延迟增加依赖于神经营养因子。在结状神经元和交感神经元中，我们都发现5-HT3R基因表达的变化与5-HT诱发电流密度的出现直接相关。
