Changes in extracellular serotonin in rat hypothalamus affect thermoregulatory function

Am J Physiol. 1998 May;274(5):R1260-7. doi: 10.1152/ajpregu.1998.274.5.R1260.

Abstract

Experiments were carried out to determine the effects of altering the serotonin (5-HT) levels in the hypothalamus on thermoregulatory function in unanesthetized restrained rats. Local perfusion of the hypothalamus with dialysis solution containing 5-hydroxytryptophan (a 5-HT precursor), fluoxetine (a 5-HT reuptake inhibitor), or high potassium significantly increased both colonic temperature (Tco) and the extracellular concentrations of 5-HT in the hypothalamus. Reciprocally, both extracellular concentration of 5-HT in the hypothalamus and Tco were decreased with a dialysis solution containing tetrodotoxin (which blocks the voltage-dependent sodium channel), zero calcium concentration, or systemic administration of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT,5-HT1A agonist). Intrahypothalamic administration of 8-OH-DPAT and (2,5-dimethoxy-4-iodophenyl)-2-aminopropane (a 5-HT2 agonist) produced hypothermic and hyperthermic effects, respectively. The results indicate that elevating the 5-HT levels in the hypothalamus activates postsynaptic 5-HT2 receptors and results in hyperthermic effects, whereas stimulation of presynaptic 5-HT1A receptors in the hypothalamus reduces the endogenous 5-HT release and results in hypothermic effects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Temperature Regulation / physiology*
  • Extracellular Space / metabolism
  • Hypothalamus / physiology*
  • Hypothalamus / ultrastructure
  • Male
  • Microdialysis
  • Rats
  • Rats, Sprague-Dawley
  • Serotonin / physiology*
  • Tetrodotoxin

Substances

  • Serotonin
  • Tetrodotoxin