Decrease In Glutamine Concentration Research Articles

Deprivation of glutamine in cell culture reveals its potential for treating cancer

The growth-stimulating capacity of calf serum (CS) in cell culture reaches a maximum of 10% with Balb 3T3 cells, remains at a plateau to 40% CS, and declines steeply to 100% CS. Growth capacity can be largely restored to the latter by a combination of cystine and glutamine. Glutamine is a conditionally essential amino acid that continues to function at very low concentrations to support the growth of nontransformed cells, but transformed cells require much larger concentrations to survive. These different requirements hold true over a 10-fold variation in background concentrations of CS and amino acids. The high requirement of glutamine for transformed cells applies to the development of neoplastically transformed foci. These observations have given rise to a novel protocol for cancer therapy based on the large difference in the need for glutamine between nontransformed and transformed cells. This protocol would stop the cumulative growth and survival of the transformed cells without reducing the growth rate of the nontransformed cells. The results call for studies of glutamine deprivation as a treatment for experimental cancer in rodents and clinical trials in humans.

Alterations of plasma glutamine and surgical stress in gastric cancer surgery.

176 Background: The plasma glutamine levels are known to decrease after major surgery, which is related to a negative clinical outcome. However, the influence of surgical stress on the decrease in the plasma glutamine concentration is unclear. The aim of this study was to evaluate the change in glutamine in relation to the types of gastrectomy and approaches as well as the amount of surgical stress evaluated by serum interleukin-6(IL-6) as an objective indicator. Methods: This was a prospective observational study. The eligibility criteria were (1) gastric adenocarcinoma of the stomach confirmed by pathology and (2) patients scheduled to receive gastrectomy with D1 or D2 lymphadenectomy for gastric cancer. Blood samples were taken at 7 AM on the day of surgery and at 12 h after surgery to measure the plasma glutamine and interleukin-6 (IL-6) levels. Results: Between May 2011 and December 2011, 81 consecutive patients were enrolled in this study. The plasma glutamine level was significantly decreased in all patients, regardless of distal or total gastrectomy and laparoscopic or open surgery. No significant differences were observed in the IL-6 level between total and distal gastrectomy patients or between patients treated via a laparoscopic or open approach. Decreases in the plasma glutamine level were positively correlated with the logarithmically transformed-plasma IL-6 (logIL6) (r = 0.471, p < 0.001) overall. Conclusions: Decreases in the glutamine concentration depended on the amount of surgical stress. When conducting a clinical trial to evaluate glutamine administration, personalized adjustment may be key to avoiding glutamine depletion in response to surgical stress.

Adverse effects of chronic intake of glutamine-supplemented diet on amino acid concentrations and protein metabolism in rat: Effect of short-term starvation

Summary Background & aims Glutamine supplementation is recommended in severe illness, preterm infants, and athletes. However, the information about side effects of chronic intake of glutamine-supplemented diet is limited. Methods Male Wistar rats were fed with glutamine-supplemented diet (GlnD). The controls were fed by standard or high-protein diets. After three months, the effect of GlnD on amino acid concentration in body fluids and protein metabolism was examined in fed and in 24 h-fasted animals. Protein synthesis was examined by the “flooding method” using phenylalanine; proteolysis on the basis of chymotrypsin-like activity (CHTLA) of proteasome and cathepsin B and L activities; amino acid concentrations were estimated using HPLC. Student’s t -tests with Bonferroni correction were used for statistical analysis. Results In the blood of GlnD fed animals sacrificed in fed state we found higher concentrations of glutamine, urea, and histidine, and lower concentration of creatinine and of a number of amino acids than in controls. The main alterations in intracellular free amino acid concentration were increased concentration of glutamine, increased concentration of histidine in skeletal muscle, and decreased concentrations of glycine, serine, and threonine in several tissues. In GlnD fed animals we found enhanced amount and concentration of protein in the kidneys, decreased protein content in tibialis muscle, and enhanced CHTLA in soleus muscle. We did not find significant effect on protein synthesis in any tissue. Starvation of animals previously fed by GlnD led to a marked decrease in glutamine concentration and an increase in glycine, serine, and threonine in plasma and in most of examined tissues, and in more significant decrease in protein synthesis in the liver, jejunum, colon, and spleen than in animals fed before starvation by standard diet. Conclusions It is concluded that chronic intake of GlnD has negative effect on protein balance in skeletal muscle, significantly alters amino acid concentrations in plasma and tissues, and results in impaired response to starvation, particularly to the rapid development of glutamine deficiency in body fluids and impaired protein synthesis in visceral tissues.

Plasma Amino Acid Concentrations in 108 Children Receiving a Pediatric Amino Acid Formulation as Part of Parenteral Nutrition

Plasma amino acid (PAA) levels can be largely normalized during parenteral nutrition (PN) in infants and children using a pediatric-specific amino acid (AA) formulation. However, these previous results were based on individual clinical studies of small populations of neonates and infants. We have now examined AA levels in 108 children (0-7 years of age) receiving a pediatric-specific AA formulation in PN using a single analytical methodology. Infants and children were enrolled in specific protocols and parents/caregivers gave informed consent. Patients were stable and receiving age-appropriate intakes of AA and non-protein calories. Samples were obtained between 8 and10 am, processed immediately, deproteinized, and AA concentrations (μmol/L) were determined on a Beckman 6300 analyzer. Means and SD were calculated for sub-populations stratified by age: 0-1 month (48 patients, n=139), 1-6 months (36 patients, n=124), 7-12 months (11 patients, n=41), and 1-7 years (13 patients, n=51). Z scores were calculated for each amino acid [(observed mean - normal control mean)/normal control SD]. When compared to the neonatal reference range, nonessential AA had Z scores that ranged from -1.84 (asparagine) to +1.48 (threonine). Only plasma free cystine, free tyrosine, and phenylalanine had Z scores outside the -2.0 to +2.0 range (95% confidence limits). Plasma free cystine values were low in all groups except neonates. Free tyrosine levels were low in all groups despite the presence of N-acetyl-L-tyrosine in the pediatric AA formulation. Phenylalanine levels were elevated only in neonates. When children 1 to 7 years old were compared with an age-matched reference range, plasma free cystine values were low (Z score -2.47), as were plasma glutamine values (-3.11), but elevations were found in the dicarboxylic amino acids aspartic acid (+2.5) and glutamic acid (+4.27). Regardless of reference range used for comparison, all essential amino acids, except phenylalanine in neonates, were within range (-2 to +2 of the 95% confidence limits). While most AAs were within the normal range, formulation modifications are needed to normalize free cystine in infants and young children, free tyrosine in all children, and phenylalanine in neonates. The decrease in glutamine concentrations in older children has been noted by our group before, and may imply limited ability to convert glutamic acid to glutamine, or increased consumption of glutamine. In either case, increased concentrations of glutamine in older children, especially those receiving home parenteral nutrition, should be considered.

EFFECT OF EXERCISE ON GLUTAMINE SYNTHESIS AND TRANSPORT IN SKELETAL MUSCLE FROM RATS

1. Reductions in plasma glutamine are observed after prolonged exercise. Three hypotheses can explain such a decrease: (i) high demand by the liver and kidney; (ii) impaired release from muscles; and (iii) decreased synthesis in skeletal muscle. The present study investigated the effects of exercise on glutamine synthesis and transport in rat skeletal muscle. 2. Rats were divided into three groups: (i) sedentary (SED; n = 12); (ii) rats killed 1 h after the last exercise bout (EX-1; n = 15); and (iii) rats killed 24 h after the last exercise bout (EX-24; n = 15). Rats in the trained groups swam 1 h/day, 5 days/week for 6 weeks with a load equivalent to 5.5% of their bodyweight. 3. Plasma glutamine and insulin were lower and corticosterone was higher in EX-1 compared with SED rats (P < 0.05 and P < 0.01, respectively). Twenty-four hours after exercise (EX-24), plasma glutamine was restored to levels seen in SED rats, whereas insulin levels were higher (P < 0.001) and corticosterone levels were lower (P < 0.01) than in EX-1. In the soleus, ammonia levels were lower in EX-1 than in SED rats (P < 0.001). After 24 h, glutamine, glutamate and ammonia levels were lower in EX-24 than in SED and EX-1 rats (P < 0.001). Soleus glutamine synthetase (GS) activity was increased in EX-1 and was decreased in EX-24 compared with SED rats (both P < 0.001). 4. The decrease in plasma glutamine concentration in EX-1 is not mediated by GS or glutamine transport in skeletal muscle. However, 24 h after exercise, lower GS may contribute to the decrease in glutamine concentration in muscle.

Simultaneous Infusion of Glutamine and Branched‐Chain Amino Acids (BCAA) to Septic Rats Does Not Have More Favorable Effect on Protein Synthesis in Muscle, Liver, and Small Intestine Than Separate Infusions

Glutamine and branched-chain amino acids (BCAA; valine, leucine, and isoleucine) are used as nutrition supplements in the treatment of proteocatabolic illness. We hypothesized that simultaneous administration of BCAA and glutamine affects protein metabolism more significantly than separate administration. In the present study, we evaluated their effect on protein synthesis in skeletal muscle, liver, and jejunum of septic rats. Twenty-four hours after induction of sepsis by subcutaneous injection of turpentine, the rats were infused for 6 hours with 5 mL of 1.75% glutamine, 1.75% BCAA, 1.75% glutamine+BCAA, or saline solution. The control group consisted of intact rats infused with saline. Protein synthesis was measured at the end of infusion by a "flooding method" with [3,4,5-(3)H]phenylalanine. In turpentine-treated animals, we observed a decrease in glutamine concentration in blood plasma and skeletal muscle, a decrease in BCAA concentration in liver and jejunum, and a decrease in protein synthesis in all tissues. Glutamine or glutamine+BCAA infusion increased glutamine concentration in plasma and muscle and stimulated protein synthesis in the liver. The BCAA infusion enhanced concentrations of BCAA in plasma and tissues, but the effect of BCAA on protein synthesis was insignificant. Synergistic effect of simultaneous infusion of glutamine and BCAA on protein synthesis was not observed. We conclude that glutamine infusion to rats with septic injury may significantly improve impaired protein synthesis in the liver and that there is no synergistic effect of glutamine and BCAA infusion on protein synthesis in skeletal muscle, liver, and jejunum.

Does glutamine contribute to immunosuppression after major burns?

The effects of glutamine concentration on the rates of lymphocyte proliferation after mitogenic stimulation and of phagocytosis by macrophages were investigated in vitro. A decrease in the glutamine concentration in culture medium from 0·6 to 0·05 mmol/l greatly decreased the rate of proliferation of human lymphocytes and of phagocytosis by mouse macrophages. In patients with major burn injury plasma glutamine concentration was 58% lower than that in normal controls and it remained low for at least 21 days after the injury. The findings indicate that the decrease in plasma glutamine concentration may contribute to the injury-induced impairment of immune function occurring after major burn injury.

Changes in the activity of glutamate related enzymes in cerebral cortex, during insulin-induced seizures.

The activity of glutamate related enzymes and the concentration of glutamine, glutamate and gamma-amino n-butyric acid (GABA) were investigated in the cerebral cortex of rats, in different stages of insulin-induced hypoglycemia. Hypoglycemia was produced by intraperitoneal injection of insulin 0.05-100 units per kg body weight. The minimum required dose to produce irreversible severe hypoglycemia was 0.5 units/kg. In 85% of the cases an insulin induced hypoglycemic convulsion, was achieved 130-150 minutes after injection. Blood glucose levels during insulin induced seizures ranged between 8-15 mg%. In the range of 0.5-100 u insulin/kg the degree of hypoglycemia and the onset of convulsions were identical. The concentration of glutamine was significantly reduced during convulsive and postconvulsive stages. Glutamate and GABA concentrations were reduced significantly in all stages of insulin-induced hypoglycemia. The decrease in glutamine concentration was concurrent with an increase in the activity of its degradative enzyme, glutaminase. This was apparent at the preconvulsive, convulsive and postconvulsive stages. The activity of other enzymes related to energy production such as glutamate dehydrogenase (GDH), glutamate transaminase (GPT) and aspartate aminotransferase (AAT) were also increased. The activity of glutamine synthase (GS) was unaffected by hypoglycemia. Insulin induced changes in glutamine, glutamate and their related enzymes could not be attributed to convulsion since a similar pattern of changes was observed in the preconvulsive and postconvulsive stages, and no changes were detected following picrotoxin-induced seizures.

Amino acid concentrations in Rhodospirillum rubrum during expression and switch-off of nitrogenase activity.

The amino acid concentrations in the phototrophic bacterium Rhodospirillum rubrum were measured during growth under nif-repressing and nif-derepressing conditions. The effects of ammonium, glutamine, darkness, phenazine methosulfate, and the inhibitors methionine sulfoximine and azaserine on amino acid levels of cells were tested. The changes were compared to changes in whole-cell nitrogenase activity and ADP-ribosylation of dinitrogenase reductase. Glutamate was the dominant amino acid under every growth condition. Glutamine levels were equivalent when cells were grown on high-ammonia (nif-repressing) medium or glutamate (nif-derepressing) medium. Thus, glutamine is not the solitary agent that controls nif expression. No other amino acid correlated with nif expression. Glutamine concentrations rose sharply when either glutamate-grown or N-starved cells were treated with ammonia, glutamine, or azaserine. Glutamine levels showed little change upon treatment of the cells with darkness or ammonium plus methionine sulfoximine. Treatment with phenazine methosulfate resulted in a decrease in glutamine concentration. The glutamine concentration varied independently of dinitrogenase reductase ADP-ribosylation, and it is concluded that an increase in glutamine concentration is neither necessary nor sufficient to initiate the modification of dinitrogenase reductase. No other amino acid exhibited changes in concentration that correlated consistently with modification. Glutamine synthetase activity and nitrogenase activity were not coregulated under all conditions, and thus the two regulatory cascades perceive different signal(s) under at least some conditions.

The alterations of rat brain gaba and glutamine induced by the organophosphorus compound cyolane

1. Levels of the amino acids GABA and glutamine were determined in the whole brain of the white albino rat Rattus norvegicus after daily injection of 1 2 , 1 4 , 1 8 , 1 16 , 1 32 and 1 100 ld 50, of cyolane. 2. With 1 2 ld 50 an increase in the level of both GABA and glutamine in the brain was recorded. 3. Dose levels of 1 4 and 1 8 ld 50 caused an increase in the level of GABA and a decrease in glutamine concentration followed by an increase from the 7th and 11th days for 1 4 and 1 8 ld 50, respectively. 4. The induced increase in GABA level started from the 2nd week for 1 16 and 1 32 ld 50 and from the 3rd week for 1 100 ld 50. 5. Dose levels of 1 16 , 1 32 and 1 100 ld 50 caused a fluctuating increase in glutamine concentration starting from the 2nd, 3rd and 6th weeks, respectively, which was followed by a fluctuating decrease at the 9th week for 1 32 and 1 100 ld 50. 6. These findings support previous findings that the enhanced transformation of glutamic acid to GABA and glutamine is a result of a disturbance in the metabolism of the glutamic acid-GABA and the glutamic acid-glutamine systems in the rat brain.

Muscle and plasma amino acids during semi-starvation in normal subjects: hypocaloric glucose vs. amino acid infusions

Normal subjects were fed hypocaloric amounts of amino acids or glucose for 3 days to separate the effects of these nutrients from those of trauma on muscle and plasma amino acids. Intracellular and plasma levels of Val, Leu and Ile were increased in both groups but were increased to a greater extent when amino acids were infused. Intracellular free glutamine concentration in muscle tissue was not significantly altered. Some of the trauma induced changes in amino acids can be replicated by maintaining normal subjects on hypocaloric amino acids; the decrease in glutamine concentration seen with trauma is not a function of hypocaloric nutrition.