Obesity or overweight in humans is a growing epidemic worldwide. New knowledge about arginine biochemistry and physiology is expected to aid in designing a novel, safe and effective way to prevent and treat obesity as well as metabolic syndrome in humans. But how does arginine act on metabolism?
There is growing interest in the metabolism of amino acids by the intestine and the portal-drained viscera (PDV). Arginine is converted to nitric oxide (NO) by NO synthase (NOS) in almost all mammalian cells, showing important roles in regulating multiple metabolic pathways involving in the metabolism of fatty acids, glucose, amino acids, and proteins through cell signaling and gene expression.
Dr. YIN Yulong’s group at Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA) studied the effects of arginine on PDV metabolism and metabolic profiles using a new technique for implanting chronic portal vein and ileal mesenteric vein catheters in pigs. The findings showed acute treatment of arginine in the portal vein increased blood flow and decreased oxygen consumption by PDV. This would enhance the entry of dietary macronutrients into the systemic circulation and the efficiency of their utilization for lean tissue gains in the body.
As expected, an increase in circulating levels of arginine increased plasma concentrations of insulin and glucagon. The rise in insulin associated with arginine infusion stimulates uptake of the sugar formed in the liver by muscle and fat tissue, but glucagon stimulates gluconeogenesis and release of the newly formed glucose from the liver to the blood stream. The fine balance between insulin and glucagon contributes the regulation of nutrient metabolism.
Additionally, plasma free fatty acid (FFA) concentrations decreased in response to arginine infusion. This metabolic change is likely due to an increase in the uptake of FFA by skeletal muscle for oxidation.
Given the current epidemic of obesity worldwide, this finding is very important and may have important implications for human health. The findings were published recently in the Amino Acids (DOI 10.1007/s00726-012-1328-5). For the paper, please click http://www.springerlink.com/content/07674k100l7263x8/fulltext.pdf
This research was jointly supported by grants from National Basic Research Project (2012CB124704), NSFC (31110103909, 31001016, 30901040, 30928018), Chinese Academy of Sciences and Knowledge Innovation Project (KZCX2-EW-412, Y022042020), Chinese Universities Scientific Funds (2012RC024), the Thousand-People-Talent program at China Agricultural University, and Texas AgriLife Research project (No. 8200)