Extracellular somatostatin measured by microdialysis in the hippocampus of freely moving rats: Evidence for neuronal release

A. Vezzani, R. Ruiz, A. Monno, M. Rizzi, N. Lindefors, R. Samanin, E. Brodin

Research output: Contribution to journalArticle

Abstract

Intracerebral microdialysis combined with a sensitive and specific radioimmunoassay was used to monitor the neuronal release of somatostatin (somatostatin-like immunoreactivity, SLI) in the dorsal hippocampus of freely moving rats. The sensitivity of the radioimmunoassay was optimized to detect 2+ was omitted and 1 mM EGTA added to the Krebs-Ringer solution and by 65.5 ± 3.2% (p <0.05) in the presence of 1 μM tetrodotoxin. Depolarizing concentrations of the Na+ channel opener veratridine (6.25, 25, 100 μM) induced 11 ± 2 (p <0.05), 17 ± 2 (p <0.05), and 21 ± 5 (p <0.01) fold increase in SLI concentration, respectively, during the first 20 min of perfusion. The effect of 100 μM veratridine was blocked by coperfusion with 5 μM tetro-dotoxin (p <0.01) and reduced by 79% (p <0.01) in the virtual absence of Ca2+. Neuronal depolarization by 20 min of perfusion with Krebs-Ringer solution containing 25 and 50 mM KCl and proportionally lowered Na+ increased the dialysate SLI 4.4 ± 1 (p <0.05) and 17 ± 3 (p <0.01) fold baseline, respectively. Ten micromolar ouabain, a blocker of Na+,K+-ATPase, increased the dialysate SLI 15-fold baseline, on average (p <0.05), during 80 min of perfusion. The results demonstrate the suitability of brain microdialysis for monitoring the neuronal release of SLI and for studying its role in synaptic transmission.

Original languageEnglish
Pages (from-to)671-677
Number of pages7
JournalJournal of Neurochemistry
Volume60
Issue number2
Publication statusPublished - 1993

Keywords

  • Extracellular space
  • Freely moving rats
  • Hippocampus
  • In vivo microdialysis
  • Neuronal somatostatin release
  • Radioimmunoas-say

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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