The role of GABAergic neuron on NMDA- and SP-induced phase delays in the suprachiasmatic nucleus neuronal activity rhythm in vitro

Neurosci Lett. 2010 Jan 14;468(3):344-7. doi: 10.1016/j.neulet.2009.11.029. Epub 2009 Nov 13.


Gamma-aminobutyric acid (GABA), and its biosynthetic enzyme, glutamic decarboxylase, are widely distributed in the suprachiasmatic nucleus (SCN). In the present study, we examined the role of the GABA(A) receptor on in vitro SCN responses to photic-like signals. We found that 100microM GABA(A) receptor antagonist bicuculline partially blocked field potentials evoked by optic nerve stimulation. NMDA- and SP-induced phase shifts of SCN neuronal activity rhythms, were blocked with 10microM bicuculline. Application of 100microM bicuculline alone induced phase advance of SCN neuronal activity rhythm. These results show that NMDA- and SP-induced phase shifts are blocked by bicuculline and suggest GABA has an important role as neurotransmitter in the neuronal network regulating phase shifts of the circadian clock.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Action Potentials
  • Animals
  • Bicuculline / pharmacology
  • Circadian Rhythm
  • Electric Stimulation
  • Evoked Potentials
  • GABA-A Receptor Antagonists
  • In Vitro Techniques
  • N-Methylaspartate / pharmacology*
  • Neurons / physiology*
  • Optic Nerve / physiology
  • Rats
  • Receptors, GABA-A / physiology*
  • Substance P / pharmacology*
  • Suprachiasmatic Nucleus / cytology
  • Suprachiasmatic Nucleus / drug effects
  • Suprachiasmatic Nucleus / physiology*


  • GABA-A Receptor Antagonists
  • Receptors, GABA-A
  • Substance P
  • N-Methylaspartate
  • Bicuculline