A reexamination of the role of GABA in the mammalian suprachiasmatic nucleus.
Three independent electrophysiological approaches in hypothalamic slices were used to test the hypothesis that gamma-amino butyric acid (GABA)A receptor activation excites suprachiasmatic nucleus (SCN) neurons during the subjective day, consistent with a recent report. First, multiple-unit recordings during either the subjective day or night showed that GABA or muscimol inhibited firing activity of the SCN population in a dose-dependent manner. Second, cell-attached recordings during the subjective day demonstrated an inhibitory effect of bath- or microapplied GABA on action currents of single SCN neurons. Third, gramicidin perforated-patch recordings showed that bicuculline increased the spontaneous firing rate during the subjective day. Therefore, electrophysiological data obtained by three different experimental methods provide evidence that GABA is inhibitory rather than excitatory during the subjective day.
Gribkoff
V K
VK
Department 409, Bristol-Myers Squibb Pharmaceutical Research Institute, Wallingford, CT 06492, USA.
Pieschl
R L
RL
Wisialowski
T A
TA
Park
W K
WK
Strecker
G J
GJ
de Jeu
M T
MT
Pennartz
C M
CM
Dudek
F E
FE
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism; D002940:Circadian Rhythm / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D018755:GABA Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D058785:GABA-A Receptor Agonists; D058787:GABA-A Receptor Antagonists; D006096:Gramicidin / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D010852:Picrotoxin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011963:Receptors, GABA-A / Q000502:physiology*; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D001640:Bicuculline; D002712:Chlorides; D018755:GABA Agonists; D018756:GABA Antagonists; D058785:GABA-A Receptor Agonists; D058787:GABA-A Receptor Antagonists; D006096:Gramicidin; D009118:Muscimol; D010852:Picrotoxin; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid