Extracellular serotonin and 5-hydroxyindoleacetic acid in hypothalamus of the unanesthetized rat measured by in vivo dialysis coupled to high-performance liquid chromatography with electrochemical detection: dialysate serotonin reflects neuronal release

Sidney B. Auerbach, Michael J. Minzenberg, Lynn O. Wilkinson

Research output: Contribution to journalArticle

182 Scopus citations


In vivo dialysis coupled to high-performance liquid chromotography with electrochemical detection (HPLC-EC) was used for measurement of extracellular serotonin (5-HT) in the hypothalamus of unanesthetized, unrestrained rats. A series of experiments was carried out to determine if 5-HT in the dialysis solution was released from nerve terminals. Fenfluramine, a 5-HT-releasing drug and fluoxetine, a 5-HT-reuptake inhibitor, both significantly increased extracellular 5-HT. Elevating potassium concentration in the dialysis solution also significantly increased 5-HT. Reciprocally, 5-HT was significantly reduced to about half of control levels with either local administration of tetrodotoxin, zero calcium dialysis solution, or systemic administration of 8-hydroxy-2-(di-n-propylamino)tetralin, a 5-HT1A agonist that suppresses 5-HT neuronal activity via activation of the somatodendritic autoreceptor. In addition, 5-HT levels were elevated during the dark portion of the light-dark cycle, a period when rats are more active. Changes in extracellular 5-hydroxyindoleacetic acid (5-HIAA) rarely followed changes in 5-HT. The results indicate that 5-HT in the dialysis solution, but not 5-HIAA, was a reliable measure of depolarization-induced release of 5-HT from nerve terminals. This is the first establishing the reliability of in vivo dialysis coupled to HPLC-EC for measurement of synaptically released 5-HT.

Original languageEnglish (US)
Pages (from-to)281-290
Number of pages10
JournalBrain Research
Issue number2
StatePublished - Oct 16 1989
Externally publishedYes



  • Dialysis
  • High-performance liquid chromatography-electrochemical detection
  • Hypothalamus
  • Rat
  • Release
  • Serotonin

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)

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