[Frontiers in Bioscience E3, 279-290, January 1, 2011]
Effects of monosodium glutamate supplementation on glutamine metabolism in adult rats
Claire Boutry1,2, Cecile Bos1,2, Hideki Matsumoto3, Patrick Even1,2, Dalila Azzout-Marniche1,2, Daniel Tome1,2 and Francois Blachier1,2
1INRA, CNRH-IdF, UMR 914 Nutrition Physiology and Ingestive Behavior, F-75005 Paris, France, 2AgroParisTech, CNRH-IdF, UMR 914 Nutrition Physiology and Ingestive Behavior, F-75005 Paris, France, 3AJINOMOTO Company, Institute of Life Sciences, Amino Acid Basic and Applied Research Group, Ajinomoto Co., Inc, Kawasaki 210-8681, Japan
TABLE OF CONTENTS
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.