Effects of 5-HT2 and 5-HT3 receptors on the modulation of nociceptive transmission in rat spinal cord according to the formalin test

Eur J Pharmacol. 2001 Jul 13;424(1):45-52. doi: 10.1016/s0014-2999(01)01117-7.

Abstract

We used the formalin test to clarify the 5-hydroxytryptamine (5-HT) receptor subtypes involved in the modulation of spinal nociceptive transmission in rats. Intrathecal administration of a 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)-tetraline (8-OH-DPAT; 1, 10, and 30 microg), or a 5-HT1B receptor agonist, 1, 4-dihydro-3-(1, 2, 3, 6-tetrahydro-4-pyridinyl)-5H-pyrrol (3, 2-b) pyridin-5-one (CP 93129; 1 and 10 microg), produced no significant change in the number of flinches. A 5-HT(2) receptor agonist, (+/-)-2, 5-dimethoxy-4-iodoamphetamine (DOI; 10, 30, and 100 microg), and a 5-HT3 receptor agonist, 2-methyl-5-HT (100 and 300 microg), produced dose-dependent decreases in the number of flinches in phases 1 (1 to 6 min) and 2 (10 to 61 min) of the test. The antinociceptive effects of DOI and 2-methyl-5-HT were antagonized by intrathecal pretreatment with a 5-HT2 receptor antagonist, ketanserin, and a 5-HT3 receptor antagonist, 3-tropanyl-3, 5-dichlorobenzoate (MDL-72222), respectively. These results suggest that 5-HT2 and 5-HT3 receptors in the spinal cord mediate antinociception to chemical stimuli.

MeSH terms

  • 8-Hydroxy-2-(di-n-propylamino)tetralin / pharmacology
  • Amphetamines / pharmacology
  • Animals
  • Dose-Response Relationship, Drug
  • Formaldehyde
  • Injections, Spinal
  • Male
  • Nociceptors / drug effects
  • Nociceptors / physiology*
  • Pain / chemically induced
  • Pain / physiopathology
  • Pain / prevention & control
  • Pain Measurement
  • Pyridines / pharmacology
  • Pyrroles / pharmacology
  • Rats
  • Rats, Wistar
  • Receptor, Serotonin, 5-HT1B
  • Receptors, Serotonin / physiology*
  • Receptors, Serotonin, 5-HT1
  • Receptors, Serotonin, 5-HT3
  • Serotonin / analogs & derivatives
  • Serotonin / pharmacology
  • Serotonin Antagonists / pharmacology
  • Serotonin Receptor Agonists / pharmacology
  • Spinal Cord / drug effects
  • Spinal Cord / physiology*
  • Synaptic Transmission / drug effects
  • Synaptic Transmission / physiology*
  • Tropanes / pharmacology

Substances

  • Amphetamines
  • Pyridines
  • Pyrroles
  • Receptor, Serotonin, 5-HT1B
  • Receptors, Serotonin
  • Receptors, Serotonin, 5-HT1
  • Receptors, Serotonin, 5-HT3
  • Serotonin Antagonists
  • Serotonin Receptor Agonists
  • Tropanes
  • 3-(1,2,5,6-tetrahydropyrid-4-yl)pyrrolo(3,2-b)pyrid-5-one
  • Formaldehyde
  • Serotonin
  • 2-methyl-5-HT
  • 8-Hydroxy-2-(di-n-propylamino)tetralin
  • bemesetron
  • 4-iodo-2,5-dimethoxyphenylisopropylamine