Effects of 5-HT1 and 5-HT2 receptor agonists and antagonists on membrane properties of motoneurons in the isolated lumbar segment of the frog spinal cord were investigated using intracellular recordings. Application of a 5-HT2A,B,C receptor agonist α-Me-5-HT evoked depolarization of the motoneuronal membrane. The co-application of α-Me-5-HT and a specific 5-HT2B receptor antagonist SB 206553 did not result in depolarization. α-Me-5-HT reduced the amplitude of medium afterhyperpolarization and increased the number of antidromic action potentials (APs). The application of an antagonist SB 206553 abolished these effects. A 5-HT1A/7 receptor agonist 8-OH-DPAT had a time-dependent effect on the number of antidromic APs, evoking an initial short-term excitation followed by an inhibition. The data obtained in our experiments indicate the presence of 5-HT1A/7 and 5-HT2B,C receptors on the postsynaptic membrane of motoneurons. We suggest a possible co-modulation of the accommodative properties of motoneurons by the two types of serotonin receptors, 5-HT2B,C and 5-HT1A.

中文翻译：

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5-HT1和5-HT2受体激动剂对青蛙脊髓运动神经元兴奋性调节的不同影响

使用细胞内记录研究了 5-HT1 和 5-HT2 受体激动剂和拮抗剂对青蛙脊髓分离腰段中运动神经元膜特性的影响。5-HT2A、B、C 受体激动剂 α-Me-5-HT 的应用引起运动神经元膜的去极化。α-Me-5-HT 和特定 5-HT2B 受体拮抗剂 SB 206553 的共同应用不会导致去极化。α-Me-5-HT 降低了超极化后介质的振幅并增加了逆向动作电位 (AP) 的数量。拮抗剂 SB 206553 的应用消除了这些影响。5-HT1A/7 受体激动剂 8-OH-DPAT 对逆向 AP 的数量具有时间依赖性影响，引起最初的短期兴奋，然后是抑制。在我们的实验中获得的数据表明运动神经元的突触后膜上存在 5-HT1A/7 和 5-HT2B,C 受体。我们建议可能通过两种血清素受体 5-HT2B,C 和 5-HT1A 共同调节运动神经元的调节特性。