Serotonergic modulation of the mudpuppy (Necturus maculatus) locomotor pattern in vitro
Serotonergic modulation of the mudpuppy (Necturus maculatus) locomotor pattern in vitro
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DOI：
10.1007/bf00229556
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发表时间：
1996-09-01
影响因子：
2
通讯作者：
Stein, RB
中科院分区：
文献类型：
--
作者：
Jovanovic, K;Petrov, T;Stein, RB
本研究的目的是：（1）研究血清素（5-HT）在调节泥小狗（Necturus maculatus）运动的中枢模式发生器（CPG）中的作用； (2)考察脊髓是否存在内在的5-羟色胺系统。这些目标是通过使用药理学和免疫细胞化学方法来实现的。为了研究运动模式和节律的调节，我们将 5-HT、其摄取阻滞剂齐美立定以及各种 5-HT 受体激动剂和拮抗剂应用于从泥小狗身上分离的体外脑干脊髓制剂。该标本由脊髓的前五段和由臂丛神经连接的右前肢组成。通过向灌注溶液中添加 NMDA 来化学激活用于运动的脊髓 CPG。在运动过程中，单侧尺屈肌和伸肌进行双极肌电图 (EMG) 记录。 5-HT 本身不会诱导运动，但它确实对 NMDA 诱导的运动具有深远的调节作用。 5-HT 使整个循环持续时间呈剂量依赖性增加，并增强了 EMC 突发持续时间。使用齐美立定表明存在调节运动节律的内源性 5-HT 释放。内源性释放被 5-HT1/5-HT2 受体拮抗剂甲硫替平拮抗。使用泥犬的整个脊髓进行的免疫细胞化学分析显示，脊髓中存在不止一种类型的血清素能神经元。它们根据细胞直径、形状和突起的分枝模式进行区分。这些神经元位于中央管腹外侧的中央灰质内。我们的结果表明，5-HT 通过发达的脊髓血清素能系统发挥作用，在调节泥犬的运动 CPG 方面发挥着重要作用。这与高等脊椎动物的报道形成鲜明对比，在高等脊椎动物中，血清素能神经支配源自脊柱上结构。
The aims of the present study were to: (1) study the role of serotonin (5-HT) in modulating the central pattern generator (CPG) underlying locomotion in the mudpuppy (Necturus maculatus); (2) investigate whether there is an intrinsic spinal serotonergic system. These aims were achieved by the use of pharmacological and immunocytochemical methods. To study modulation of the locomotor pattern and rhythm, we applied 5-HT, its uptake blocker zimelidine, and a variety of 5-HT receptor agonists and antagonists to an in vitro brainstem-spinal cord preparation isolated from the mudpuppy. The preparation consisted of the first five segments of the spinal cord and the right forelimb attached by the brachial plexus. The spinal CPG for locomotion was activated chemically by adding NMDA to the superfusing solution. During locomotion, bipolar electromyographic (EMG) recordings were made unilaterally from flexor and extensor ulnae muscles. 5-HT on its own did not induce locomotion, but it did have a profound modulatory effect on NMDA-induced locomotion. 5-HT produced a dose-dependent increase in the overall cycle duration and enhanced the EMC burst duration. Use of zimelidine indicated that there is an endogenous release of 5-HT which modulated the locomotor rhythm. The endogenous release was antagonized by 5-HT1/5-HT2 receptor antagonist methiothepin. Immunocytochemical analysis, in which the entire spinal cord of the mudpuppy was used, revealed that there were more than one type of spinal serotonergic neuron. They were differentiated according to the cell diameter, shape, and arborization pattern of their processes. These neurons were located within the central gray matter ventrolateral to the central canal. Our results suggest that 5-HT plays an important role in modulating the locomotor CPG in the mudpuppy, by acting through a well-developed spinal serotonergic system. This is in contrast to what has been reported in higher vertebrates, where serotonergic innervation is derived from supraspinal structures.