Bicuculline blocks neuropeptide Y-induced phase advances when microinjected in the suprachiasmatic nucleus of Syrian hamsters

Brain Res. 1995 Mar 27;675(1-2):333-6. doi: 10.1016/0006-8993(95)00018-l.


Microinjection of neuropeptide Y (NPY) into the suprachiasmatic nucleus of the hypothalamus (SCN) during the middle of the subjective day (i.e. circadian time 6) causes large phase advances in circadian rhythms. The present study demonstrates that microinjection of the gamma-aminobutyric acid (GABA) antagonist, bicuculline, completely blocks NPY-induced phase advances. These data indicate that GABAA activity within the SCN may mediate the phase shifting effects of some stimuli on the circadian pacemaker.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Bicuculline / administration & dosage
  • Bicuculline / pharmacology*
  • Cricetinae
  • GABA-A Receptor Antagonists
  • Male
  • Mesocricetus
  • Microinjections
  • Neuropeptide Y / antagonists & inhibitors*
  • Neuropeptide Y / pharmacology
  • Receptors, GABA-A / metabolism
  • Regression Analysis
  • Suprachiasmatic Nucleus / metabolism
  • Suprachiasmatic Nucleus / physiology*


  • GABA-A Receptor Antagonists
  • Neuropeptide Y
  • Receptors, GABA-A
  • Bicuculline