Tryptophan metabolism is a physiological integrator regulating circadian rhythms

Area of Science:

• Chronobiology
• Nutritional Neuroscience
• Metabolomics

Background:

• The circadian clock synchronizes physiology with Earth's 24-hour cycle, regulated by environmental cues like light and food.
• Interactions between diet and light in regulating circadian homeostasis are not well understood, particularly the role of essential amino acids.

Purpose of the Study:

• To investigate the role of essential amino acids, specifically tryptophan, in modulating circadian homeostasis.
• To explore how tryptophan metabolism interacts with light cues to influence circadian rhythms.

Main Methods:

• Mice were fed diets lacking specific essential amino acids, with behavioral rhythms monitored.
• Tryptophan metabolism was analyzed using isotope tracing, transcriptomics, and metabolomics.
• Combined dietary and light interventions were employed alongside multi-omics approaches.

Main Results:

• Dietary tryptophan depletion altered behavioral rhythms in mice.
• Tryptophan metabolism exhibited time- and light-dependent regulation.
• Tryptophan metabolites were found to modulate metabolic and transcriptional programs, buffering photic cues and influencing suprachiasmatic nucleus and liver clock function.

Conclusions:

• Tryptophan metabolism acts as a key modulator of circadian homeostasis by integrating environmental cues.
• Tryptophan metabolism presents a potential target for pharmacological interventions to address disrupted circadian rhythm phenotypes.