The role of inositol trisphosphate-induced Ca2+ release from IP3-receptor in the rat suprachiasmatic nucleus on circadian entrainment mechanism

Neurosci Lett. 1999 Mar 26;263(2-3):125-8. doi: 10.1016/s0304-3940(99)00111-1.


Synchronization between the environmental lighting cycle and the circadian clock in the suprachiasmatic nucleus (SCN) is correlated with Ca2+ increase. The mechanism underlying the increase of Ca2+ and its relation to clock resetting are unknown. To address these issues, we examined the possibility whether inositol 1,4,5-trisphosphate receptor (IP3-R), which regulate intracellular Ca2+, was involved in the circadian rhythm component of the rat SCN. A novel IP3-induced Ca2+ release modulator, 2-amino-ethoxy diphenylborate (2APB), blocked optic nerve stimulation-induced neuronal field potentials in the SCN. Furthermore, glutamate-induced phase delay of the circadian firing pattern in the SCN was also blocked completely by 2APB in vitro. Together, these data suggest the possibility that IP3-induced Ca2+ release through IP3-R plays a role in the entrainment of the mammalian circadian clock, the SCN.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Boron Compounds / pharmacology
  • Calcium / metabolism*
  • Calcium Channels / drug effects
  • Calcium Channels / physiology*
  • Circadian Rhythm / physiology*
  • Darkness
  • Electric Stimulation
  • Evoked Potentials / drug effects
  • Evoked Potentials / physiology
  • Functional Laterality
  • Glutamic Acid / pharmacology
  • Homeostasis
  • In Vitro Techniques
  • Inositol 1,4,5-Trisphosphate / pharmacology
  • Inositol 1,4,5-Trisphosphate / physiology*
  • Inositol 1,4,5-Trisphosphate Receptors
  • Neurons / drug effects
  • Neurons / physiology*
  • Optic Nerve / physiology
  • Rats
  • Receptors, Cytoplasmic and Nuclear / drug effects
  • Receptors, Cytoplasmic and Nuclear / physiology*
  • Suprachiasmatic Nucleus / physiology*


  • Boron Compounds
  • Calcium Channels
  • Inositol 1,4,5-Trisphosphate Receptors
  • Receptors, Cytoplasmic and Nuclear
  • Glutamic Acid
  • Inositol 1,4,5-Trisphosphate
  • 2-aminoethoxydiphenyl borate
  • Calcium