Effects of GABA and anxiolytics on the single unit discharge of suprachiasmatic neurons in rat hypothalamic slices

S. Y. Liou, Shigenobu Shibata, H. E. Albers, S. Ueki

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Abstract

The effects of gamma-aminobutyric acid (GABA), muscimol, baclofen and the anxiolytics; diazepam (DZP), flurazepam (FZP) and zopiclone on single-unit neural activities in the suprachiasmatic nucleus (SCN) were investigated using the rat hypothalamic slice preparation. Exposure of the slice to GABA 10-4 M produced inhibitory responses in 65% of the 49 SCN neurons examined. The threshold concentration of GABA ranged from 10-6 to 10-f4 M. Neurons responsive to GABA were not found to be restricted to a subdivision of the SCN, but were diffusely distributed throughout the nucleus. DZP, FZP and zopiclone produced responses similar to those of GABA. The inhibitory effects of GABA (10-5 M) were potentiated by coadministration of DZP (10-5 M). Muscimol and baclofen (10-7 M to 10-4 M) also inhibited SCN neuronal activity in a dose-dependent manner. Bicuculline (10-5 M-10-4 M) scarcely affected the baclofen-induced inhibition ( 1 6) but strongly antagonized the effects of muscimol ( 6 6), GABA ( 6 8) and DZP ( 4 5). These results suggest that the receptors mediating the inhibitory effects of GABA and anxiolytics within the SCN may be GABAA and/or GABAB or GABA-BDZ receptor complex, respectively.

Original languageEnglish
Pages (from-to)103-107
Number of pages5
JournalBrain Research Bulletin
Volume25
Issue number1
DOIs
Publication statusPublished - 1990
Externally publishedYes

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Keywords

  • Anxiolytics
  • Brain slice
  • Gamma-aminobutyric acid
  • Single unit activity
  • Suprachiasmatic nucleus

ASJC Scopus subject areas

  • Neuroscience(all)

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