Arginine and disease states

Area of Science:

• Biochemistry
• Nutritional Science
• Physiology

Background:

• Arginine's role in mammalian metabolism is primarily linked to growth.
• Adult mammals are generally believed to synthesize sufficient arginine endogenously.
• Dietary arginine's necessity beyond growth stages is debated.

Purpose of the Study:

• To investigate the biological functions of arginine beyond its role in growth.
• To examine the impact of liver injury on ammonia detoxification and arginine metabolism.
• To evaluate arginine's influence on glucose tolerance, insulin secretion, and lean body mass.

Main Methods:

• Review of studies on ammonia intoxication, orotic acid excretion, and L-amino acid feeding.
• Analysis of data from carnivorous species and experimental models of liver injury (CCl4, ethanol, galactosamine, partial hepatectomy).
• Examination of arginine's effects on metabolic pathways, including mitochondrial function and urea synthesis.

Main Results:

• Orotic acid excretion, indicative of liver injury and ammonia overload, can be suppressed by arginine.
• Liver injury disrupts ammonia detoxification and mitochondrial metabolism, impacting urea cycle enzymes.
• Dietary arginine influences insulin secretion, glucose tolerance, and lean body mass repletion in animals.

Conclusions:

• Arginine's dietary requirement may extend beyond growth, potentially including adults and infants.
• Arginine deficiency might occur in various disease states, necessitating further investigation.
• Experimental models offer new avenues for studying arginine's role in conditions like Reye's syndrome and ammonia intoxication disorders.