Altered brain and muscle amino-acid levels due toremote injury during glutamine supplementation

Abstract

Glutamine (GLN) has aroused considerable interest among clinicians andnutritionists after studies demonstrated conclusively profound GLN depletion during critical illness. Although the brain plays an important role in GLN metabolism, little is known concerning changes in cerebral handling of GLN following injury. We have evaluated in a rat trauma (bilateral femur fractures) model, the nutritional efficacy of GLN-rich diet and the remote injury-induced changes in amino-acid (AA) contents of brain and muscle tissues. Both control and traumatised rats were starved for 2 days and then pair-fed for 4 days, either a basic liquid diet (BioServ # F1259) or an isonitrogenous test diet which contained the same basic diet from which 10% nitrogen (N) was replaced by GLN-N. Protein efficiency ratio as well as plasma levels of anabolic growth hormone and insulin did not change due to GLN-enriched diet. Remote injury-induced changes in GLN and glutamic acid (GLU) during GLN-rich diet were minimal in brain tissues; whereas GLN levels were decreased in plasma and muscle, GLU levels were increased in plasma and decreased in muscle tissues. The AA levels of brain tissues, in general, were maintained within narrow limits during GLN supplementation in control and injured rats. An increased influx of tryptophan and increased synthesis of the neurotransmitter serotonin were suggested due to GLN-enriched diet.