Visceral afferents directly activate catecholamine neurons in the solitary tract nucleus
Visceral afferents directly activate catecholamine neurons in the solitary tract nucleus
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DOI：
10.1523/jneurosci.3502-07.2007
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发表时间：
2007-11-28
影响因子：
5.3
通讯作者：
Andresen, Michael C.
中科院分区：
文献类型：
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作者：
Appleyard, Suzanne M.;Marks, Daniel;Andresen, Michael C.
脑干A(2)/C-2神经元是孤束核(NTS)内的儿茶酚胺(CA)神经元，影响许多稳态功能，包括心血管反射、食物摄入和应激。由于NTS是感觉内脏传入和CNS之间的主要接口，NTS CA神经元非常适合通过向大脑多个区域的投射来协调复杂的反应。为了测试NTS CA神经元如何处理由孤束(ST)传入的内脏传入信息，我们用表达TH-EGFP(酪氨酸羟基酶启动子控制下的增强型绿色荧光蛋白)的转基因小鼠鉴定了CA神经元，并在水平脑片上记录了对ST激活的突触反应。ST刺激可在90%的NTS CA神经元中诱发大幅度、短潜伏期的谷氨酸能EPSCs(ST-EpSCs)。在神经元内部，ST-EPSCs潜伏期恒定，很少失灵，ST-EPSCs频率较高时显著降低，表明NTS CA神经元接受来自传入终末的直接单突触联系。NTS CA神经元只接受一个或两个传入纤维的直接ST输入，其中一半也接受幅度较小的间接输入。高达90%的ST波可诱发NTS CA神经元的动作电位。然而，感觉传入信息通过NTS CA神经元的传递严重依赖于A型钾电流(I-KA)的表达，当激活该电流时，ST-激活的动作电位的成功率为37%。饱腹肽CCK在突触前促进了NTS CA神经元中一半的谷氨酸传递。因此，NTS CA神经元由内脏传入直接驱动，其输出受突触前肽受体和突触后钾通道的调节。
Brainstem A(2)/C-2 neurons are catecholamine (CA) neurons within the solitary tract nucleus (NTS) that influence many homeostatic functions, including cardiovascular reflexes, food intake, and stress. Because NTS is a major interface between sensory visceral afferents and the CNS, NTS CA neurons are ideally suited to coordinate complex responses by their projections to multiple brain regions. To test how NTS CA neurons process visceral afferent information carried by solitary tract (ST) afferents, we identified CA neurons using transgenic mice expressing TH-EGFP (enhanced green fluorescent protein under the control of the tyrosine hydroxylase promoter) and recorded synaptic responses to ST activation in horizontal slices. ST shocks evoked large-amplitude, short-latency, glutamatergic EPSCs (ST-EPSCs) in 90% of NTS CA neurons. Within neurons, ST-EPSCs had constant latency, rarely failed, and depressed substantially at high ST frequencies, indicating that NTS CA neurons receive direct monosynaptic connections from afferent terminals. NTS CA neurons received direct ST inputs from only one or two afferent fibers, with one-half also receiving smaller amplitude indirect inputs. Up to 90% of ST shocks evoked action potentials in NTS CA neurons. However, transmission of sensory afferent information through NTS CA neurons critically depended on the expression of an A-type potassium current (I-KA), which when active attenuated ST-activated action potentials to a 37% success rate. The satiety peptide, cholecystokinin, presynaptically facilitated glutamate transmission in one-half of NTS CA neurons. Thus, NTS CA neurons are directly driven by visceral afferents with output being modulated by presynaptic peptide receptors and postsynaptic potassium channels.