Myths and reality about the effects of glutamate. Compilation of scientific data of modern world literature

The aim of our scientific work was to study the existing experimental models of glutamate effects on the body and to understand the mechanisms of this effect and its possible consequences. To achieve this goal, we have studied different sources of scientific medical literature. Results. In a healthy body, glutamic acid is secreted by brain neurons in the required amount as a neurotransmitter and participates in the main information flows of human body. Sodium glutamate, which enters the body with food in large quantities, affects the body, causing general toxic effects and has a local effect on the stomach, intestines, salivary glands and pancreas and so on. Based on the scientific literature, experimental models that study the effects of glutamate are divided into two types: models in which glutamate enters the body orally and when glutamate is administered subcutaneously and intraperitoneally in the neonatal period of life. In the first route of administration, glutamate causes a toxic effect, which is manifested in increased catalytic activity in the blood serum of alanine aminotransferase, aspartate aminotransferase and gamma-glutamyltranspeptidase in 2.5; 1.6; and 1.5 times, respectively, while the activity of alkaline phosphatase remained at control levels, indicating a pronounced hepatotoxic effect of monosodium glutamate as a dietary supplement. It causes an increase in content of total and tyrosine-containing peptides in the blood serum, increase of substances of low and medium molecular weight, as well as an increase in the values of intoxication, which indirectly indicates a violation of the detoxification of endogenous metabolites in the liver of experimental animals. Ingestion of sodium glutamate within the recommended doses has not been shown to cause marked pathological changes in the mucous, muscular and serous membranes of the gastric wall, but there is a slight fullness of the vessels of the submucosal membrane. It has been found that in high doses, sodium glutamate has a local pathogenic effect on the tissues of the stomach, which consists in thinning all layers of its wall, desquamation of the mucous membrane and its disorganization by reducing the size of gastric glands, increasing the number of vessels and their fullness with blood. One of the mechanisms of pathogenic effect of sodium glutamate is the contact local and free radical oxidizing effect on gastric tissues. In the oral route of administration of glutamate there are no phenomena of fat growth (obesity) as epidermal, which is characteristic of the abdominal form of obesity, so and pararectal, parallelic, pararenal and retroperitoneal, which is characteristic for the visceral form of obesity. In the subcutaneous and intraperitoneal routes of administration of glutamate in the neonatal period of life in experimental animals, glutamate causes hypersecretion of hydrochloric acid, the development of lesions manifested by hemorrhage, erosions and ulcers in the gastric mucosa and obesity. Prolonged administration of monosodium glutamate significantly enhances the striking effects of stress on the gastric mucosa. Morphological studies of the submandibular salivary glands of rats on the background of glutamate-induced obesity confirm the development of pathological changes, as evidenced by the detected vacuolar dystrophy in the acinar region, perivascular and periductal edema. On the background of abdominal obesity, dystrophic processes were found in the acinuses and minor dystrophic changes in the intraparticle inserts. Conclusion. In the subcutaneous and intraperitoneal routes of administration of glutamate in the neonatal period of life in experimental animals, glutamate causes hypersecretion of hydrochloric acid, the development of lesions manifested by hemorrhage, erosions and ulcers in the gastric mucosa and obesity. Prolonged administration of monosodium glutamate significantly enhances the striking effects of stress on the gastric mucosa. Morphological studies of the submandibular salivary glands of rats on the background of glutamate-induced obesity confirm the development of pathological changes, as evidenced by the detected vacuolar dystrophy in the acinar region, perivascular and periductal edema. On the background of abdominal obesity, dystrophic processes were found in the acinuses and minor dystrophic changes in the intraparticle inserts. There is no doubt in the fact, which is based on the results of numerous experimental studies and covered in professional scientific litefrature, that the abdominal form of glutamate-induced obesity is possible only with subcutaneous and intraperitoneal routes of its administration in the neonatal period of life and while intraorall way of administration does not occur.

Optimization of compatible solutes for improving survival of freeze-dried Lactobacillus delbrueckii subsp. bulgaricus using Box-Behnken design

Lactobacillus delbrueckii subsp. bulgaricus is widely used in yogurt as a starter. The freeze-drying process may cause bacteria death. In the present work, the effect of three solutes (NaCl, sorbitol, and sodium glutamate) in MRS on viability of L.bulgaricus during freeze-drying was investigated. The optimal combination of adequate solutes was chosen by Box-Behnken Design. The survival rate and viable counts in freeze-dried powder, as well as the viable counts in broth, were used as responses. The results revealed that the optimum combination of solutes in MRS broth were 0.50% NaCl, 0.19% sorbitol, and 0.06% sodium glutamate. Under these optimal conditions, the survival rate was 53.2±0.14%, the viable counts in freeze-dried powder was 8.51±0.23×1010 CFU/g, and the viable counts in broth was 6.05±0.19 ×108 CFU/mL, which were increased by 17.18%, 15.94%, and 17.31%, respectively, compared to the control. This research demonstrated the possibility of viability improvement of L.bulgaricus, which may provide a feasible reference for industrial development.

Dynamics of Change of Biochemical Indicators in Rats under the Influence of Sodium Glutamate

The purpose of the study was to determine metabolic parameters (alpha-amylase, alanine aminotransferase and aspartate aminotransferase, gamaglutamyl transpeptidase, glycoproteins and chondroitin sulfates) at the stages of sodium glutamate intake and after withdrawal. Materials and methods. Studies were conducted on 65 white male rats of reproductive age (2.5-3 months); the experimental group received 70 mg/kg of sodium glutamate per live weight for 8 weeks. The control group of animals received a standard diet. Before drug withdrawal, rats were studied every week, after drug withdrawal the studies were performed every two weeks (10, 12, 14, 16 weeks). Results and discussion. The study of the enzyme activity of alpha-amylase showed that this index increased on the average 1.3-fold compared with the control values, and at the end of the period when the rats were fed with sodium glutamate (8 weeks), the index increased by 3.85 times, alanine aminotransferase – by 12.3 times, aspartate aminotransferase – by 1.4 times, gamaglutamyl transpeptidase – by 2.7 times, glycoproteins – by 1.4 times, chondroitin sulfate – by 1.2 times. After transferring the animals to a normal diet, no recovery of the indices was found. According to the studied indicators sodium glutamate has a toxic effect on the liver, pancreas with elements of systemic inflammation. At the stages of discontinuation of monosodium glutamate recovery of most of the studied biochemical markers is not established. Alanine aminotransferase, determined on the 16th day after the abolition of monosodium glutamate, was reduced by 1.33 times compared to the last 8 weeks of admission, gamaglutamyl transpeptidase after 10 weeks was reduced by 1.5 times, after 12 weeks – by 0.4 times, after 14 and 16 weeks, the values corresponded to the control values at 10 week, the alpha-amylase level was reduced by 1.26 times, at 16 weeks – by 2.29 times, but they did not reach the control values. At the end of the study (16 weeks), the level of chondroitin sulfates was increased compared to 8 weeks of feeding animals with glutamate sodium by 1.27 times, and relative to control – by 1.56 times. There was a decrease in glycoprotein content at 16 weeks compared with 8 weeks of observation by 1.3 times, but did not reach the level of intact animals. Conclusion. Thus, the results of serum biochemical studies of rats treated with monosodium glutamate indicated the development of intoxication and its effect on biochemical markers, which were reflected in the dynamics of enzyme activity, inflammation and fibrosis. Most biochemical markers (except gamaglutamyl transpeptidase and aspartate aminotransferase) at the end of the experiment did not reach the level of intact animals, which is apparently due to the chronicity of the pathological process. In rats after discontinuation of monosodium glutamate from 10 to 16 weeks of the experiment, changes in biochemical parameters were observed, which indicated a toxic effect, which was accompanied by the development of subacute inflammatory process. After the transfer of animals to a normal diet, recovery is not established. Sodium glutamate according to the studied parameters has a toxic effect on the liver, pancreas with elements of systemic inflammation

Enhancement of GABA content in Hongqu wine by optimisation of fermentation conditions using response surface methodology

γ-aminobutyric acid (GABA) is an important inhibitory neurotransmitter in the human body, but its content decreases with age. So it is suitable to supplement the body's GABA from diet. Hongqu wine is popular because of the addition of Monascus strains in the saccharification process, which makes the wine rich in functional ingredients such as GABA, and monacolin K. In this study, the fermentation parameters of Hongqu wine were optimised to maximise the GABA content through response surface methodology (RSM). The optimal conditions were as follows: 500 g of steamed rice was mixed with 115.4% of boiled water containing 10 g of sodium glutamate and adjusted to pH 3.8 with lactic acid, and then 32% of Hongqu seed inoculum was added. After 5 days of fermentation at 28 °C, 1.5 g of activated yeast was inoculated for ethanol fermentation at 30 °C for 5 days. Finally, the average content of GABA in Hongqu wine amounted to 710.24 mg L^–1, which is close to the value predicted by RSM model (692.44 mg L^–1), indicating the statistical fit is good. This provided technical support and theoretical guidance for the production of Hongqu wine rich in GABA by two-stage fermentation.

A Panax notoginseng Root Tip Meristem Biosensor and Its Sensing Kinetics for Five Important Nitrogen Nutrients

Plants absorb nitrogen mainly through their roots. Nitrogen sensing is required for the absorption and transport of different nitrogen nutrients. In this study, we constructed biosensors with immobilized Panax notoginseng root tip meristems based on a three-electrode system and successfully determined the kinetics of the interactions between the P. notoginseng root tip meristems and five important nitrogen nutrients, namely, urea, sodium nitrate, sodium glutamate, disodium inosinate, and disodium guanylate. We discovered that the biosensor’s sensing kinetics was similar to the enzyme–substrate kinetics, and the receptor–ligand interconnected allosteric interaction constant Ka (mol/L), analogous to the Michaelis constant, was calculated. The result showed that the root tip meristems of two- to four-year-old P. notoginseng plants had a higher capacity to sense inorganic nitrogen nutrients (sodium nitrate and urea) than the three organic nitrogen nutrients. The ability of the plants to sense inorganic nitrogen nutrients decreased with an increase in plant age. The sensing sensitivity of four-year-old P. notoginseng plants to disodium inosinate and disodium guanylate was 100- to 10,000-fold lower than that of the two- and three-year-old plants. Additionally, the capability to sense sodium glutamate decreased initially and then increased with an increase in plant age. The biosensors reached an ultra-sensitive level ( 1 × 10 − 22 mol/L) in sensing the five nitrogen nutrients and exhibited advantages such as good stability and reproducibility, low cost, a simple structure, and a rapid response, providing a new approach for quantitative determination of the capability of plants to sense different nitrogen nutrients.