Mechanism Underlying the Protective Effect of Glycine in Energetic Disturbances in Brain Tissues under Hypoxic Conditions

An Update of the Promise of Glycine Supplementation for Enhancing Physical Performance and Recovery

Glycine, the simple amino acid, is a key component of muscle metabolism with proven cytoprotective effects and hypothetical benefits as a therapeutic nutrient. Cell, in vitro, and animal studies suggest that glycine enhances protection against muscle wasting by activating anabolic pathways and inhibiting proteolytic gene expression. Some evidence indicates that glycine supplementation may enhance peak power output, reduce lactic acid accumulation during high-intensity exercise, and improve sleep quality and recovery. This literature review critically explores glycine's potential as an ergogenic aid and its relevance to muscle regeneration, muscle strength, endurance exercise performance, and sleep quality. It also underscores key areas for future research. It is concluded that more randomized controlled clinical trials in humans are needed to confirm glycine's potential as a dietary supplement to support muscle function, recovery, and overall athletic performance as an ergogenic aid and to establish nutritional recommendations for athletic performance. Also, it is essential to consider that high doses (>500 mg/kg of body mass) could induce cytotoxic effects and contribute to acute glutamate toxicity.

Autocatalytic cycle in the pathogenesis of diabetes mellitus: biochemical and pathophysiological aspects of metabolic therapy with natural amino acids on the example of glycine

In this work systematization (classification) of biochemical and physiological processes that cause disorders in the human body during the development of diabetes mellitus is carried out. The development of the disease is considered as the interaction and mutual reinforcement of two groups of parallel processes. The first group has a molecular nature and it is associated with impairment of ROS-regulation system which includes NADPH oxidases, RAGE receptors, mitochondria, cellular peroxireductase system and the immune system. The second group has a pathophysiological nature and it is associated with impairment of microcirculation and liver metabolism. The analysis of diabetes biochemistry based on different published references yields a creation of a block diagram evaluating the disease development over time. Two types of autocatalytic processes were identified: autocatalysis in the cascade of biochemical reactions and "cross-section" catalysis, in which biochemical and pathophysiological processes reinforce each other. The developed model has shown the possibility of using pharmacologically active natural metabolite glycine as a medicine inhibiting the development of diabetes. Despite the fact that glycine is a substitute amino acid the drop in the glycine blood concentration occurs even in the early stages of diabetes development and can aggravate the disease. It is shown that glycine is a potential blocker of key autocatalytic cycles, including biochemical and pathophysiological processes. The analysis of the glycine action based on the developed model is in complete agreement with the results of clinical trials in which glycine has improved blood biochemistry of diabetic patients and thereby it prevents the development of diabetic complications.

Geometries of vasculature bifurcation can affect the level of trophic damage during formation of a brain ischemic lesion

Ischemic lesion is a common cause of various diseases in humans. Brain tissue is especially sensitive to this type of damage. A common reason for the appearance of an ischemic area is a stop in blood flow in some branch of the vasculature system. Then, a decreasing concentration gradient results in a low mean level of oxygen in surrounding tissues. After that, the biochemical ischemic cascade spreads. In this review, we examine these well-known events from a new angle. It is stressed that there is essential evidence to predict the formation of an ischemic micro-area at the base of vascular bifurcation geometries. Potential applications to improve neuroprotection are also discussed.

On the regulative role of the glutamate receptor in mitochondria

The purpose of this work was to study the regulative role of the glutamate receptor found earlier in the brain mitochondria. In the present work a glutamate-dependent signaling system with similar features was detected in mitochondria of the heart. The glutamate-dependent signaling system in the heart mitochondria was shown to be suppressed by γ-aminobutyric acid (GABA). The GABA receptor presence in the heart mitochondria was shown by golding with the use of antibodies to α- and β-subunits of the receptor. The activity of glutamate receptor was assessed according to the rate of synthesis of hydrogen peroxide. The glutamate receptor in mitochondria could be activated only under conditions of hypoxic stress, which in model experiments was imitated by blocking Complex I by rotenone or fatty acids. The glutamate signal in mitochondria was shown to be calcium- and potential-dependent and the activation of the glutamate cascade was shown to be accompanied by production of hydrogen peroxide. It was discovered that H2O2 synthesis involves two complexes of the mitochondrial electron transfer system - succinate dehydrogenase (SDH) and fatty acid dehydrogenase (ETF:QO). Thus, functions of the glutamate signaling system are associated with the system of respiration-glycolysis switching (the Pasteur-Crabtree) under conditions of hypoxia.

The role of glycine in regulated cell death

The cytoprotective effects of glycine against cell death have been recognized for over 28 years. They are expressed in multiple cell types and injury settings that lead to necrosis, but are still not widely appreciated or considered in the conceptualization of cell death pathways. In this paper, we review the available data on the expression of this phenomenon, its relationship to major pathophysiologic pathways that lead to cell death and immunomodulatory effects, the hypothesis that it involves suppression by glycine of the development of a hydrophilic death channel of molecular dimensions in the plasma membrane, and evidence for its impact on disease processes in vivo.

Metabolomic investigation of regional brain tissue dysfunctions induced by global cerebral ischemia

Background

To get a broader view of global ischemia-induced cerebral disorders at the metabolic level, a nuclear magnetic resonance-based metabolomic study was performed to evaluate the metabolic profile changes on regional brain tissues of female and male mice upon bilateral common carotid arteries occlusion (BCCAO) operation.

Results

Significant metabolic disorders were observed in both cerebral cortex and hippocampus tissues of the experimental mice upon global cerebral ischemic attack. Multiple amino acids were identified as the dominantly perturbed metabolites. It was also shown that although the metabolic profile change patterns in the brain tissues were quite similar in male and female BCCAO mice, metabolic disorders in the cortex tissues were more severe in the female mice than in the male mice.

Conclusions

In the present study, significant changes in amino acid metabolic pathways were confirmed in the early stage of global ischemia. Meanwhile, cerebral metabolic dysfunctions were more severe in the female BCCAO mice than in the male mice, suggesting that gender may play a role in different metabolic responses to the ischemic attack, which may provide an important hypothesis for a better understanding of the clinically observed gender-dependent pathological outcome of cerebral ischemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s12868-016-0256-9) contains supplementary material, which is available to authorized users.

Glutamate induces H2O2 synthesis in nonsynaptic brain mitochondria

Mitochondrial reactive oxygen species regulate many important biological processes. We studied H2O2 formation by nonsynaptic brain mitochondria in response to the addition of low concentrations of glutamate, an excitatory neurotransmitter. We demonstrated that glutamate at concentrations from 10 to 50 μM stimulated the H2O2 generation in mitochondria up to 4-fold, in a dose-dependent manner. The effect of glutamate was observed only in the presence of Ca(2+) (20 μM) in the incubation medium, and the rate of calcium uptake by the brain mitochondria was increased by up to 50% by glutamate. Glutamate-dependent effects were sensitive to the NMDA receptor inhibitors MK-801 (10 μM) and D-AP5 (20 μM) and the inhibitory neurotransmitter glycine (5mM). We have shown that the H2O2 formation caused by glutamate is associated with complex II and is dependent on the mitochondrial potential. We have found that nonsynaptic brain mitochondria are a target of direct glutamate signaling, which can specifically activate H2O2 formation through mitochondrial respiratory chain complex II. The H2O2 formation induced by glutamate can be blocked by glycine, an inhibitory neurotransmitter that prevents the deleterious effects of glutamate in brain mitochondria.