Rapid glucocorticoid stimulation and GABAergic inhibition of hippocampal serotonergic response: In vivo dialysis in the lizard Anolis carolinensis

Tangi R. Summers, John M. Matter, Jennifer M. McKay, Patrick J. Ronan, Earl T. Larson, Kenneth J. Renner, Cliff H. Summers

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

Central serotonin (5-HT) is activated during stressful situations and aggressive interactions in a number of species. Glucocorticoids secreted peripherally during stressful events feed back on central systems and may affect 5-HT mediation of stress-induced behavioral events. To test the neuromodulatory effect of stress hormone secretion, serotonin overflow was measured from the hippocampus of the lizard Anolis carolinensis. Microdialysis was used to collect repeated samples from anesthetized lizards, with perfusate measured by HPLC with electrochemical analysis. Following initially high levels of 5-HT, concentrations stabilized to basal levels after approximately 2 h. Intracortical infusion of 200 ng/ml corticosterone evoked transient increases in 5-HT release of approximately 400%. The effect of corticosterone on 5-HT overflow appears to be dose dependent as 20 ng/ml stimulated an increase of 200%, whereas 2 ng/ml stimulated a 50% increase. Administration of 0.1 and 1 ng/ml GABA via the dialysis probe significantly inhibited 5-HT overflow by 20 and 40%, respectively. The duration of GABA inhibition is greater than the stimulatory response for glucocorticoids. Short-lived glucocorticoid stimulation of 5-HT release suggests a possible mechanism for endocrine mediation of continuously changing social behavioral events.

Original languageEnglish (US)
Pages (from-to)245-253
Number of pages9
JournalHormones and Behavior
Volume43
Issue number1
DOIs
StatePublished - Jan 2003

Keywords

  • Anolis carolinensis
  • Corticosterone
  • Hippocampus
  • Lizard
  • Medial cortex
  • Microdialysis
  • Serotonin
  • γ-Aminobutyric acid

ASJC Scopus subject areas

  • Endocrinology
  • Endocrine and Autonomic Systems
  • Behavioral Neuroscience

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