Somatostatin regulates central clock function and circadian responses to light

Area of Science:

• Neuroscience
• Chronobiology
• Molecular Biology

Background:

• The suprachiasmatic nucleus (SCN) processes light cues to regulate daily rhythms and seasonal changes.
• The role of somatostatin (SST) in SCN light responses and its influence on circadian and photoperiodic functions remain largely unexamined.
• Understanding SCN circuits is crucial for deciphering how light impacts behavior and physiology.

Purpose of the Study:

• To investigate the role of somatostatin (SST) signaling in the SCN's response to light.
• To determine how SST influences circadian rhythms, photoperiodic encoding, and sex-specific responses to light.
• To elucidate the mechanisms by which SST modulates SCN network function.

Main Methods:

• Utilized cell-fate mapping to investigate light-induced SST regulation in the SCN.
• Employed Sst knockout mice (Sst-/-) to assess behavioral and physiological responses to altered light conditions.
• Analyzed SCN neuronal morphology, photoperiodic encoding, and intercellular synchrony.

Main Results:

• SST in the SCN is regulated by light via de novo Sst activation.
• Sst-/- mice exhibit enhanced circadian plasticity to photoperiod, jetlag, and constant light, with eliminated sex differences due to increased male plasticity.
• Lack of SST signaling alters retinorecipient neuron numbers in the SCN core and modulates SCN photoperiodic encoding, network after-effects, and synchrony in a sex-specific manner.

Conclusions:

• SST signaling is a key regulator of daily rhythms and SCN responses to light, with significant sex-specific modulation.
• SST influences behavioral plasticity and the processing of light information within the SCN network.
• These findings reveal novel peptide signaling mechanisms underlying central clock function and light adaptation.