Functional Roles of Gastrin-Releasing Peptide-Producing Neurons in the Suprachiasmatic Nucleus: Insights into Photic Entrainment and Circadian Regulation

May 22, 2025The Journal of neuroscience : the official journal of the Society for Neuroscience

Roles of Gastrin-Releasing Peptide Neurons in the Brain’s Clock for Light-Based Timing and Daily Rhythm Control

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Abstract

Chemogenetic stimulation of SCN gastrin-releasing peptide-producing neurons can induce phase shifts in behavioral rhythms.

  • The suprachiasmatic nucleus (SCN) is the central circadian clock in mammals, regulating daily rhythms in behavior and physiology.
  • SCN gastrin-releasing peptide-producing neurons (GRPNs) primarily project to the thalamus and hypothalamus.
  • SCN GRPNs receive most of their synaptic inputs from within the SCN itself.
  • Neither the absence of GRP nor the removal of SCN GRPNs significantly altered circadian locomotor activity rhythms or .
  • Calcium imaging revealed that SCN GRPNs respond quickly to light stimulation, showing increased activity after exposure to white light.
  • These findings indicate that while SCN GRPNs are involved in photic entrainment, their role may overlap with other neuronal populations.

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Key numbers

7
Phase Shift Induction
Mice expressing hM3Dq in SCN GRPNs showed significant phase shifts.
87±3.6%
Neuronal Projection Targets
Indicates the specificity of the genetic manipulation in GRPNs.

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