Citrulline and nitrogen homeostasis: an overview

Area of Science:

• Biochemistry
• Nutritional Science
• Physiology

Background:

• Citrulline (Cit) is a non-essential amino acid with emerging regulatory properties.
• Its role in nitrogen homeostasis has gained attention in the last decade.
• Cit is synthesized in the intestine and not taken up by the liver.

Purpose of the Study:

• To explore the metabolic properties and regulatory roles of Cit.
• To understand Cit's mechanism in preventing amino acid catabolism.
• To investigate the potential benefits of Cit for muscle protein synthesis and function.

Main Methods:

• Literature review on Cit metabolism and function.
• Analysis of Cit's role in nitrogen homeostasis.
• Exploration of potential signaling pathways, including mTOR.

Main Results:

• Cit synthesis in the intestine spares arginine and glutamine from hepatic uptake.
• This sparing effect prevents urea cycle activation and amino acid catabolism.
• Preliminary data suggest Cit's involvement in the mTOR pathway, potentially benefiting muscle.

Conclusions:

• Citrulline is crucial for maintaining nitrogen homeostasis.
• Cit may positively influence muscle protein synthesis, content, and functionality.
• Further research is required to fully elucidate Cit's mechanisms of action and its role in nitrogen metabolism.