Effects of monosodium glutamate supplementation on glutamine metabolism in adult rats

Front Biosci (Elite Ed). 2011 Jan 1;3:279-90. doi: 10.2741/e243.

Abstract

Monosodium glutamate (MSG) is a worldwide used flavor enhancer. Supplemental glutamate may impact physiological functions. The aim of this study was to document the metabolic and physiological consequences of supplementation with 2% MSG (w/w) in rats. After 15 days-supplementation and following the ingestion of a test meal containing 2% MSG, glutamic acid accumulated for 5h in the stomach and for 1h in the small intestine. This coincided with a significant decrease of intestinal glutaminase activity, a marked specific increase in plasma glutamine concentration and a transient increase of plasma insulin concentration. MSG after chronic or acute supplementation had no effect on food intake, body weight, adipose tissue masses, gastric emptying rate, incorporation of dietary nitrogen in gastrointestinal and other tissues, and protein synthesis in intestinal mucosa, liver and muscles. The only significant effects of chronic supplementation were a slightly diminished gastrocnemius muscle mass, increased protein mass in intestinal mucosa and decreased protein synthesis in stomach. It is concluded that MSG chronic supplementation promotes glutamine synthesis in the body but has little effect on the physiological functions examined.

MeSH terms

  • Analysis of Variance
  • Animals
  • DNA Primers / genetics
  • Dietary Supplements
  • Gastric Emptying / drug effects
  • Gastrointestinal Transit / drug effects
  • Gene Expression Regulation, Enzymologic / drug effects*
  • Glutamic Acid / metabolism
  • Glutaminase / metabolism
  • Glutamine / biosynthesis*
  • Glutamine / blood
  • Intestinal Mucosa / drug effects
  • Intestinal Mucosa / metabolism
  • Kinetics
  • Muscle, Skeletal / drug effects
  • Muscle, Skeletal / growth & development
  • Nitrogen / metabolism
  • Protein Biosynthesis / drug effects*
  • Rats
  • Sodium Glutamate / pharmacology*

Substances

  • DNA Primers
  • Glutamine
  • Glutamic Acid
  • Glutaminase
  • Nitrogen
  • Sodium Glutamate