Beato M, Nistri A
Biophysics Sector, International School for Advanced Studies (SISSA), Trieste, Italy.
Proc Biol Sci. 1998 Nov 7;265(1410):2073-80. doi: 10.1098/rspb.1998.0542.
The neurotransmitter serotonin (5-HT) induces rhythmic motor patterns (fictive locomotion) of the neonatal rat spinal cord in vitro; this is a useful experimental model to study the generation of a motor programme at exclusively spinal level. Nevertheless, 5-HT slows down the fictive locomotion typically elicited by activation of NMDA glutamate receptors, suggesting a complex action of this monoamine. By means of electrophysiological recordings from multiple ventral roots we demonstrated that the decrease caused by 5-HT in NMDA-induced periodicity was dose-dependent, enhanced after pharmacological blocking of 5-HT2 excitatory receptors, and imitated by pharmacological agonists of the 5-HT1 receptor family. Selective blockers of the 5-HT1A or 5-HT1B/D receptor classes, either alone or in combination, largely (but not completely) attenuated this inhibitory action of 5-HT. It is concluded that the principal inhibitory action of 5-HT on the spinal locomotor network was mediated by certain subtypes of the 5-HT1 receptor class, which tends to oppose the 5-HT2 receptor-mediated excitation of the same network.
神经递质5-羟色胺（5-HT）可在体外诱导新生大鼠脊髓产生节律性运动模式（虚拟运动）；这是一个用于研究仅在脊髓水平产生运动程序的有用实验模型。然而，5-HT会减缓通常由NMDA谷氨酸受体激活所引发的虚拟运动，这表明这种单胺具有复杂的作用。通过对多条腹根进行电生理记录，我们证明5-HT导致的NMDA诱导的周期性降低是剂量依赖性的，在对5-HT2兴奋性受体进行药理学阻断后增强，并可被5-HT1受体家族的药理学激动剂模拟。5-HT1A或5-HT1B/D受体类别的选择性阻滞剂单独或联合使用，可在很大程度上（但并非完全）减弱5-HT的这种抑制作用。得出的结论是，5-HT对脊髓运动网络的主要抑制作用是由5-HT1受体类别的某些亚型介导的，这些亚型倾向于对抗5-HT2受体介导的同一网络的兴奋作用。
