Changes in serotonin-induced potentials during spinal cord development.
Changes in serotonin-induced potentials during spinal cord development.
复制标题
脊髓发育过程中血清素诱导电位的变化。
DOI：
10.1152/jn.1993.69.4.1338
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发表时间：
1993
影响因子：
2.5
通讯作者：
Gao,BX
中科院分区：
文献类型：
--
作者：
Ziskind-Conhaim,L;Seebach,BS;Gao,BX
1. 在胚胎和新生大鼠的离体脊髓中研究了运动神经元对血清素（5-羟色胺，5-HT）的反应以及 5-HT 投射到腹角的生长模式。 2. 5-HT 投射首先出现在妊娠第 16-17 天（E16-E17）的腰脊髓中，并定位于侧索和腹索。到 E18 时，突起已长成腹角，出生后 1-2 天，它们与运动神经元胞体紧密相连。 3.在E16-E17，响应于5-HT的浴应用，在腰部运动神经元的细胞内记录到1-4mV的缓慢上升的去极化电位。这些潜力在 E18 之后并不明显；此时5-HT产生平均振幅6mV的持久去极化，膜电阻增加11%。从 E18 开始，5-HT 还诱导高频快速上升电位，该电位被谷氨酸、γ-氨基丁酸和甘氨酸拮抗剂阻断。 4. 运动神经元对 5-HT 的反应在出生后显着增加，此时 5-HT 产生 19 mV 的平均去极化和动作电位的重复放电。 5.河豚毒素和高浓度Mg2+并没有降低持久去极化的幅度，这表明它们是由5-HT直接作用于运动神经元膜而产生的。 6. 在所有发育年龄，5-HT 均降低背根诱发电位的幅度。反应受到抑制既不是由于 5-HT 诱导的去极化，也不是运动神经元兴奋性降低的结果。 7.使用各种5-HT激动剂和拮抗剂研究了5-HT诱导电位的药理学特征。研究结果表明，5-HT 对脊髓神经元的作用是通过多种 5-HT 受体亚型介导的。 8. 我们的结果表明，在 5-HT 投射长成腹角之前，5-HT 会兴奋脊髓神经元。然而，当运动核中 5-HT 投射密度增加时，5-HT 诱导电位的特征发生了变化。
1. Motoneuron responses to serotonin (5-hydroxytryptamine, 5-HT), and the growth pattern of 5-HT projections into the ventral horn were studied in the isolated spinal cord of embryonic and neonatal rats. 2. 5-HT projections first appeared in lumbar spinal cord at days 16-17 of gestation (E16-E17) and were localized in the lateral and ventral funiculi. By E18, the projections had grown into the ventral horn, and at 1-2 days after birth they were in close apposition to motoneuron somata. 3. At E16-E17, slow-rising depolarizing potentials of 1-4 mV were recorded intracellularly in lumbar motoneurons in response to bath application of 5-HT. These potentials were not apparent after E18; at that time 5-HT generated long-lasting depolarizations with an average amplitude of 6 mV, and an increase of 11% in membrane resistance. Starting at E18, 5-HT also induced high-frequency fast-rising potentials that were blocked by antagonists of glutamate, gamma-aminobutyric acid, and glycine. 4. Motoneuron responses to 5-HT increased significantly after birth, when 5-HT produced an average depolarization of 19 mV and repetitive firing of action potentials. 5. Tetrodotoxin and high Mg2+ did not reduce the amplitude of the long-lasting depolarizations, which suggested that they were produced by direct action of 5-HT on motoneuron membrane. 6. At all developmental ages, 5-HT reduced the amplitude of dorsal root-evoked potentials. The suppressed responses were neither due to 5-HT-induced depolarization nor the result of a decrease in motoneuron excitability. 7. The pharmacological profile of 5-HT-induced potentials was studied with the use of various agonists and antagonists of 5-HT. The findings indicated that the actions of 5-HT on spinal neurons were mediated via multiple 5-HT receptor subtypes. 8. Our results suggested that 5-HT excited spinal neurons before 5-HT projections grew into the ventral horn. The characteristics of 5-HT-induced potentials changed, however, at the time when the density of 5-HT projections increased in the motor nuclei.