Organic cation transporter inhibition increases medial hypothalamic serotonin under basal conditions and during mild restraint

Na Feng, Christopher A. Lowry, Jodi L. Lukkes, Miles Orchinik, Gina L. Forster, Kenneth J. Renner

Research output: Contribution to journalArticle

16 Scopus citations

Abstract

The dorsomedial hypothalamus (DMH) has been implicated in the coordination of stress responses. Restraint stress or systemic corticosterone (CORT) treatment induces a rapid increase in tissue concentrations of serotonin (5-hydroxytryptamine; 5-HT) in the DMH. Although the mechanism for rapid changes in 5-HT concentrations in the DMH is not clear, earlier results suggest that stress-induced increases in CORT may inhibit 5-HT transport from the extracellular fluid by acting on corticosterone-sensitive organic cation transporters (OCTs). We tested the hypothesis that perfusion of the medial hypothalamus (MH), which includes the DMH, with the OCT blocker decynium 22 (D-22) would potentiate the effects of mild restraint on extracellular 5-HT. Male Sprague-Dawley rats, implanted with a microdialysis probe into the MH, were treated with reverse-dialysis of D-22 (20 μM; 40 min) or vehicle and subjected to either 40 min mild restraint or undisturbed control conditions. Perfusates collected from a separate group of rats were evaluated for the effect of restraint on extracellular CORT concentrations in the MH. Reverse-dialysis of D-22 induced an increase (200%) in extracellular 5-HT concentrations in the MH in undisturbed control rats. Restraint in the absence of D-22 did not significantly affect MH CORT or 5-HT concentrations. However, perfusion of the MH with D-22 during restraint led to an increased magnitude and duration of extracellular 5-HT concentrations, relative to D-22 by itself. These results are consistent with the hypothesis that OCTs in the DMH contribute to the clearance of 5-HT from the extracellular fluid under both baseline conditions and mild restraint.

Original languageEnglish (US)
Pages (from-to)105-113
Number of pages9
JournalBrain Research
Volume1326
DOIs
Publication statusPublished - Apr 22 2010

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Keywords

  • 5-hydroxytryptamine
  • Dorsomedial hypothalamus (DMH)
  • OCT3
  • Organic cation transporter
  • Restraint stress

ASJC Scopus subject areas

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

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