Different Effects of 5-HT1 and 5-HT2 Receptor Agonists on Excitability Modulation of Motoneurons in Frog Spinal Cord

• Published in: Journal of evolutionary biochemistry and physiology 2019-07, Vol.55 (4), p.284-292
• Main Authors: Kalinina, N. A., Zaitsev, A. V., Vesselkin, N. P.
• Format: Article
• Language: English
• Subjects: 8-Hydroxy-2-(di-n-propylamino)tetralin; Afterhyperpolarization; Agonists; Animal Physiology; Biochemistry; Biomedical and Life Sciences; Comparative and Ontogenic Biochemistry; Depolarization; Evolutionary Biology; Excitability; Life Sciences; Membrane potential; Motor neurons; Receptor mechanisms; Serotonin receptors; Serotonin S1 receptors; Serotonin S2 receptors; Spinal cord
• ISSN: 0022-0930; 1608-3202
• DOI: 10.1134/S0022093019040045

Effects of 5-HT 1 and 5-HT 2 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-HT 2A,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-HT 2B 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-HT 1A/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-HT 1A/7 and 5-HT 2B,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-HT 2B,C and 5-HT 1A .