Abstract
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.
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Abbreviations
- RMP:
-
resting membrane potential
- AP:
-
action potential
- 5-HT:
-
serotonin
- fAHP:
-
fast afterhyperpolarization
- mAHP:
-
medium afterhyperpolarization
- α-Me-5-HT (α-Methyl-5-hydroxytryptamine maleate):
-
specific agonist of 5-HT2A,2B,2C-receptors
- 8-OH-DPAT(±)-(8-hydroxy-2-(di-n-propylamino)tetralin hydrobromide):
-
agonist of 5-HT1A/7-receptors
- sumatriptan (3-[2-(Dimethylamino) ethyl]-N-methyl-1H-indole-5-methanesulfonamide succinate):
-
agonist of 5-HT 1B/D-receptors
- ketanserin (3-[2-[4-(4-Fluorobenzoyl)-1-piperidinyl]ethyl]-2,4[1H,3H]-quinazolinedione tartrate):
-
selective antagonist of 5-HT2A-receptors
- SB 206553 (3,5-Dihydro-5-methyl-N-3-pyridinylbenzo[1,2-b:4,5-b’]dipyrrole-1(2H)-carboxamide hydrochloride:
-
selective antagonist of 5-HT2B,2C-receptors
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Funding
This study was implemented under the state assignment (reg. no. AAAA-A18-118012290372-0). Pharmacological studies were supported by the Russian Foundation for Basic Research (grant no. 18-04-00247).
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All applicable international, national and institutional principles of handling and using experimental animals for scientific purposes were observed.
This study did not involve human subjects as research objects.
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Russian Text © The Author(s), 2019, published in Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, 2019, Vol. 55, No. 4, pp. 255–262.
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Kalinina, N.A., Zaitsev, A.V. & Vesselkin, N.P. Different Effects of 5-HT1 and 5-HT2 Receptor Agonists on Excitability Modulation of Motoneurons in Frog Spinal Cord. J Evol Biochem Phys 55, 284–292 (2019). https://doi.org/10.1134/S0022093019040045
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DOI: https://doi.org/10.1134/S0022093019040045