Pharmacological interventions in human aging.

Pharmacological interventions are emerging as potential avenues of alleviating age-related disease. However, the knowledge of ongoing clinical trials as they relate to aging and pharmacological interventions is dispersed across a variety of mediums. In this review we summarize 136 age-related clinical trials that have been completed or are ongoing. Furthermore, we establish a database that describe the trials (AgingDB, www.agingdb.com) keeping track of the previous and ongoing clinical trials, alongside their outcomes. The aim of this review and database is to give people the ability to easily query for their trial of interest and stay up to date on the latest results. In sum, herein we give an overview of the current pharmacological strategies that have been applied to target human aging.

Defining the progeria phenome.

Progeroid disorders are a heterogenous group of rare and complex hereditary syndromes presenting with pleiotropic phenotypes associated with normal aging. Due to the large variation in clinical presentation the diseases pose a diagnostic challenge for clinicians which consequently restricts medical research. To accommodate the challenge, we compiled a list of known progeroid syndromes and calculated the mean prevalence of their associated phenotypes, defining what we term the 'progeria phenome'. The data were used to train a support vector machine that is available at https://www.mitodb.com and able to classify progerias based on phenotypes. Furthermore, this allowed us to investigate the correlation of progeroid syndromes and syndromes with various pathogenesis using hierarchical clustering algorithms and disease networks. We detected that ataxia-telangiectasia like disorder 2, spastic paraplegia 49 and Meier-Gorlin syndrome display strong association to progeroid syndromes, thereby implying that the syndromes are previously unrecognized progerias. In conclusion, our study has provided tools to evaluate the likelihood of a syndrome or patient being progeroid. This is a considerable step forward in our understanding of what constitutes a premature aging disorder and how to diagnose them.

Oxoglutarate dehydrogenase complex controls glutamate-mediated neuronal death.

Brain injury is accompanied by neuroinflammation, accumulation of extracellular glutamate and mitochondrial dysfunction, all of which cause neuronal death. The aim of this study was to investigate the impact of these mechanisms on neuronal death. Patients from the neurosurgical intensive care unit suffering aneurysmal subarachnoid hemorrhage (SAH) were recruited retrospectively from a respective database. In vitro experiments were performed in rat cortex homogenate, primary dissociated neuronal cultures, B35 and NG108-15 cell lines. We employed methods including high resolution respirometry, electron spin resonance, fluorescent microscopy, kinetic determination of enzymatic activities and immunocytochemistry. We found that elevated levels of extracellular glutamate and nitric oxide (NO) metabolites correlated with poor clinical outcome in patients with SAH. In experiments using neuronal cultures we showed that the 2-oxoglutarate dehydrogenase complex (OGDHC), a key enzyme of the glutamate-dependent segment of the tricarboxylic acid (TCA) cycle, is more susceptible to the inhibition by NO than mitochondrial respiration. Inhibition of OGDHC by NO or by succinyl phosphonate (SP), a highly specific OGDHC inhibitor, caused accumulation of extracellular glutamate and neuronal death. Extracellular nitrite did not substantially contribute to this NO action. Reactivation of OGDHC by its cofactor thiamine (TH) reduced extracellular glutamate levels, Ca2+ influx into neurons and cell death rate. Salutary effect of TH against glutamate toxicity was confirmed in three different cell lines. Our data suggest that the loss of control over extracellular glutamate, as described here, rather than commonly assumed impaired energy metabolism, is the critical pathological manifestation of insufficient OGDHC activity, leading to neuronal death.

High-confidence cancer patient stratification through multiomics investigation of DNA repair disorders.

Multiple cancer types have limited targeted therapeutic options, in part due to incomplete understanding of the molecular processes underlying tumorigenesis and significant intra- and inter-tumor heterogeneity. Identification of novel molecular biomarkers stratifying cancer patients with different survival outcomes may provide new opportunities for target discovery and subsequent development of tailored therapies. Here, we applied the artificial intelligence-driven PandaOmics platform ( https://pandaomics.com/ ) to explore gene expression changes in rare DNA repair-deficient disorders and identify novel cancer targets. Our analysis revealed that CEP135, a scaffolding protein associated with early centriole biogenesis, is commonly downregulated in DNA repair diseases with high cancer predisposition. Further screening of survival data in 33 cancers available at TCGA database identified sarcoma as a cancer type where lower survival was significantly associated with high CEP135 expression. Stratification of cancer patients based on CEP135 expression enabled us to examine therapeutic targets that could be used for the improvement of existing therapies against sarcoma. The latter was based on application of the PandaOmics target-ID algorithm coupled with in vitro studies that revealed polo-like kinase 1 (PLK1) as a potential therapeutic candidate in sarcoma patients with high CEP135 levels and poor survival. While further target validation is required, this study demonstrated the potential of in silico-based studies for a rapid biomarker discovery and target characterization.

Nuclear morphology is a deep learning biomarker of cellular senescence.

Cellular senescence is an important factor in aging and many age-related diseases, but understanding its role in health is challenging due to the lack of exclusive or universal markers. Using neural networks, we predict senescence from the nuclear morphology of human fibroblasts with up to 95% accuracy, and investigate murine astrocytes, murine neurons, and fibroblasts with premature aging in culture. After generalizing our approach, the predictor recognizes higher rates of senescence in p21-positive and ethynyl-2'-deoxyuridine (EdU)-negative nuclei in tissues and shows an increasing rate of senescent cells with age in H&E-stained murine liver tissue and human dermal biopsies. Evaluating medical records reveals that higher rates of senescent cells correspond to decreased rates of malignant neoplasms and increased rates of osteoporosis, osteoarthritis, hypertension and cerebral infarction. In sum, we show that morphological alterations of the nucleus can serve as a deep learning predictor of senescence that is applicable across tissues and species and is associated with health outcomes in humans.

Severe Spinal Cord Injury in Rats Induces Chronic Changes in the Spinal Cord and Cerebral Cortex Metabolism, Adjusted by Thiamine That Improves Locomotor Performance.

Our study aims at developing knowledge-based strategies minimizing chronic changes in the brain after severe spinal cord injury (SCI). The SCI-induced long-term metabolic alterations and their reactivity to treatments shortly after the injury are characterized in rats. Eight weeks after severe SCI, significant mitochondrial lesions outside the injured area are demonstrated in the spinal cord and cerebral cortex. Among the six tested enzymes essential for the TCA cycle and amino acid metabolism, mitochondrial 2-oxoglutarate dehydrogenase complex (OGDHC) is the most affected one. SCI downregulates this complex by 90% in the spinal cord and 30% in the cerebral cortex. This is associated with the tissue-specific changes in other enzymes of the OGDHC network. Single administrations of a pro-activator (thiamine, or vitamin B1, 1.2 mmol/kg) or a synthetic pro-inhibitor (triethyl glutaryl phosphonate, TEGP, 0.02 mmol/kg) of OGDHC within 15-20 h after SCI are tested as protective strategies. The biochemical and physiological assessments 8 weeks after SCI reveal that thiamine, but not TEGP, alleviates the SCI-induced perturbations in the rat brain metabolism, accompanied by the decreased expression of (acetyl)p53, increased expression of sirtuin 5 and an 18% improvement in the locomotor recovery. Treatment of the non-operated rats with the OGDHC pro-inhibitor TEGP increases the p53 acetylation in the brain, approaching the brain metabolic profiles to those after SCI. Our data testify to an important contribution of the OGDHC regulation to the chronic consequences of SCI and their control by p53 and sirtuin 5.

ARDD 2020: from aging mechanisms to interventions.

Aging is emerging as a druggable target with growing interest from academia, industry and investors. New technologies such as artificial intelligence and advanced screening techniques, as well as a strong influence from the industry sector may lead to novel discoveries to treat age-related diseases. The present review summarizes presentations from the 7th Annual Aging Research and Drug Discovery (ARDD) meeting, held online on the 1st to 4th of September 2020. The meeting covered topics related to new methodologies to study aging, knowledge about basic mechanisms of longevity, latest interventional strategies to target the aging process as well as discussions about the impact of aging research on society and economy. More than 2000 participants and 65 speakers joined the meeting and we already look forward to an even larger meeting next year. Please mark your calendars for the 8th ARDD meeting that is scheduled for the 31st of August to 3rd of September, 2021, at Columbia University, USA.

New methodologies in ageing research.

Ageing is arguably the most complex phenotype that occurs in humans. To understand and treat ageing as well as associated diseases, highly specialised technologies are emerging that reveal critical insight into the underlying mechanisms and provide new hope for previously untreated diseases. Herein, we describe the latest developments in cutting edge technologies applied across the field of ageing research. We cover emerging model organisms, high-throughput methodologies and machine-driven approaches. In all, this review will give you a glimpse of what will be pushing the field onwards and upwards.

Diurnal regulation of the function of the rat brain glutamate dehydrogenase by acetylation and its dependence on thiamine administration.

Glutamate dehydrogenase (GDH) is essential for the brain function and highly regulated, according to its role in metabolism of the major excitatory neurotransmitter glutamate. Here we show a diurnal pattern of the GDH acetylation in rat brain, associated with specific regulation of GDH function. Mornings the acetylation levels of K84 (near the ADP site), K187 (near the active site), and K503 (GTP-binding) are highly correlated. Evenings the acetylation levels of K187 and K503 decrease, and the correlations disappear. These daily variations in the acetylation adjust the GDH responses to the enzyme regulators. The adjustment is changed when the acetylation of K187 and K503 shows no diurnal variations, as in the rats after a high dose of thiamine. The regulation of GDH function by acetylation is confirmed in a model system, where incubation of the rat brain GDH with acetyl-CoA changes the enzyme responses to GTP and ADP, decreasing the activity at subsaturating concentrations of substrates. Thus, the GDH acetylation may support cerebral homeostasis, stabilizing the enzyme function during diurnal oscillations of the brain metabolome. Daytime and thiamine interact upon the (de)acetylation of GDH in vitro. Evenings the acetylation of GDH from control animals increases both IC50GTP and EC50ADP . Mornings the acetylation of GDH from thiamine-treated animals increases the enzyme IC50GTP . Molecular mechanisms of the GDH regulation by acetylation of specific residues are proposed. For the first time, diurnal and thiamine-dependent changes in the allosteric regulation of the brain GDH due to the enzyme acetylation are shown.

Human Exonuclease 1 (EXO1) Regulatory Functions in DNA Replication with Putative Roles in Cancer.

Human exonuclease 1 (EXO1), a 5'→3' exonuclease, contributes to the regulation of the cell cycle checkpoints, replication fork maintenance, and post replicative DNA repair pathways. These processes are required for the resolution of stalled or blocked DNA replication that can lead to replication stress and potential collapse of the replication fork. Failure to restart the DNA replication process can result in double-strand breaks, cell-cycle arrest, cell death, or cellular transformation. In this review, we summarize the involvement of EXO1 in the replication, DNA repair pathways, cell cycle checkpoints, and the link between EXO1 and cancer.

Aging and drug discovery.

Multiple interventions in the aging process have been discovered to extend the healthspan of model organisms. Both industry and academia are therefore exploring possible transformative molecules that target aging and age-associated diseases. In this overview, we summarize the presented talks and discussion points of the 5th Annual Aging and Drug Discovery Forum 2018 in Basel, Switzerland. Here academia and industry came together, to discuss the latest progress and issues in aging research. The meeting covered talks about the mechanistic cause of aging, how longevity signatures may be highly conserved, emerging biomarkers of aging, possible interventions in the aging process and the use of artificial intelligence for aging research and drug discovery. Importantly, a consensus is emerging both in industry and academia, that molecules able to intervene in the aging process may contain the potential to transform both societies and healthcare.

Thiamine preserves mitochondrial function in a rat model of traumatic brain injury, preventing inactivation of the 2-oxoglutarate dehydrogenase complex.

BACKGROUND AND PURPOSE: Based on the fact that traumatic brain injury is associated with mitochondrial dysfunction we aimed at localization of mitochondrial defect and attempted to correct it by thiamine. EXPERIMENTAL APPROACH: Interventional controlled experimental animal study was used. Adult male Sprague-Dawley rats were subjected to lateral fluid percussion traumatic brain injury. Thiamine was administered 1 h prior to trauma; cortex was extracted for analysis 4 h and 3 d after trauma. KEY RESULTS: Increased expression of inducible nitric oxide synthase (iNOS) and tumor necrosis factor receptor 1 (TNF-R1) by 4 h was accompanied by a decrease in mitochondrial respiration with glutamate but neither with pyruvate nor succinate. Assays of TCA cycle flux-limiting 2-oxoglutarate dehydrogenase complex (OGDHC) and functionally linked enzymes (glutamate dehydrogenase, glutamine synthetase, pyruvate dehydrogenase, malate dehydrogenase and malic enzyme) indicated that only OGDHC activity was decreased. Application of the OGDHC coenzyme precursor thiamine rescued the activity of OGDHC and restored mitochondrial respiration. These effects were not mediated by changes in the expression of the OGDHC sub-units (E1k and E3), suggesting post-translational mechanism of thiamine effects. By the third day after TBI, thiamine treatment also decreased expression of TNF-R1. Specific markers of unfolded protein response did not change in response to thiamine. CONCLUSION AND IMPLICATIONS: Our data point to OGDHC as a major site of damage in mitochondria upon traumatic brain injury, which is associated with neuroinflammation and can be corrected by thiamine. Further studies are required to evaluate the pathological impact of these findings in clinical settings.

Positive correlation between rat brain glutamate concentrations and mitochondrial 2-oxoglutarate dehydrogenase activity.

Glutamate is a key metabolite and major excitatory neurotransmitter, degraded through transformation to 2-oxoglutarate which is further catabolized by 2-oxoglutarate dehydrogenase complex (OGDHC). Both the glutamate excitotoxicity and impaired OGDHC activity are hallmarks of neurodegeneration. This work quantifies a relationship between the brain OGDHC activity and glutamate levels, assessing its diagnostic value to characterize (patho)physiology. A moderate to strong positive correlation of the two parameters determined under varied physiological settings (brain regions, seasons, gender, pregnancy, rat line), is revealed. Mitochondrial impairment (OGDHC inhibition or acute hypobaric hypoxia) decreases the interdependence, even when the parameter means do not change significantly. Compared to the cortex, the cerebellum exhibits a lower inter-individual glutamate variation and a weaker glutamate-OGDHC interdependence. Specific metabolism of the brain regions is also characterized by a positive correlation between glutamate and γ-aminobutyric acid (GABA) concentrations in the cortex but not in the cerebellum. In contrast, a strong positive correlation between glutamate and glutamine is present in both the cortex and cerebellum. The differences in metabolic correlations are in line with transcriptomics data which suggest that glutamate distribution between competitive pathways contributes to the brain-region-specific features of the interdependences of glutamate and OGDHC or GABA.

The Antioxidant Cofactor Alpha-Lipoic Acid May Control Endogenous Formaldehyde Metabolism in Mammals.

The healthy human body contains small amounts of metabolic formaldehyde (FA) that mainly results from methanol oxidation by pectin methylesterase, which is active in a vegetable diet and in the gastrointestinal microbiome. With age, the ability to maintain a low level of FA decreases, which increases the risk of Alzheimer's disease and dementia. It has been shown that 1,2-dithiolane-3-pentanoic acid or alpha lipoic acid (ALA), a naturally occurring dithiol and antioxidant cofactor of mitochondrial α-ketoacid dehydrogenases, increases glutathione (GSH) content and FA metabolism by mitochondrial aldehyde dehydrogenase 2 (ALDH2) thus manifests a therapeutic potential beyond its antioxidant property. We suggested that ALA can contribute to a decrease in the FA content of mammals by acting on ALDH2 expression. To test this assumption, we administered ALA in mice in order to examine the effect on FA metabolism and collected blood samples for the measurement of FA. Our data revealed that ALA efficiently eliminated FA in mice. Without affecting the specific activity of FA-metabolizing enzymes (ADH1, ALDH2, and ADH5), ALA increased the GSH content in the brain and up-regulated the expression of the FA-metabolizing ALDH2 gene in the brain, particularly in the hippocampus, but did not impact its expression in the liver in vivo or in rat liver isolated from the rest of the body. After ALA administration in mice and in accordance with the increased content of brain ALDH2 mRNA, we detected increased ALDH2 activity in brain homogenates. We hypothesized that the beneficial effects of ALA on patients with Alzheimer's disease may be associated with accelerated ALDH2-mediated FA detoxification and clearance.

Multiple Forms of Glutamate Dehydrogenase in Animals: Structural Determinants and Physiological Implications.

Glutamate dehydrogenase (GDH) of animal cells is usually considered to be a mitochondrial enzyme. However, this enzyme has recently been reported to be also present in nucleus, endoplasmic reticulum and lysosomes. These extramitochondrial localizations are associated with moonlighting functions of GDH, which include acting as a serine protease or an ATP-dependent tubulin-binding protein. Here, we review the published data on kinetics and localization of multiple forms of animal GDH taking into account the splice variants, post-translational modifications and GDH isoenzymes, found in humans and apes. The kinetic properties of human GLUD1 and GLUD2 isoenzymes are shown to be similar to those published for GDH1 and GDH2 from bovine brain. Increased functional diversity and specific regulation of GDH isoforms due to alternative splicing and post-translational modifications are also considered. In particular, these structural differences may affect the well-known regulation of GDH by nucleotides which is related to recent identification of thiamine derivatives as novel GDH modulators. The thiamine-dependent regulation of GDH is in good agreement with the fact that the non-coenzyme forms of thiamine, i.e., thiamine triphosphate and its adenylated form are generated in response to amino acid and carbon starvation.

Inhibition of mitochondrial 2-oxoglutarate dehydrogenase impairs viability of cancer cells in a cell-specific metabolism-dependent manner.

2-Oxoglutarate dehydrogenase (OGDH) of the tricarboxylic acid (TCA) cycle is often implied to be inactive in cancer, but this was not experimentally tested. We addressed the question through specific inhibition of OGDH by succinyl phosphonate (SP). SP action on different cancer cells was investigated using indicators of cellular viability and reactive oxygen species (ROS), metabolic profiling and transcriptomics. Relative sensitivity of various cancer cells to SP changed with increasing SP exposure and could differ in the ATP- and NAD(P)H-based assays. Glioblastoma responses to SP revealed metabolic sub-types increasing or decreasing cellular ATP/NAD(P)H ratio under OGDH inhibition. Cancer cell homeostasis was perturbed also when viability indicators were SP-resistant, e.g. in U87 and N2A cells. The transcriptomics database analysis showed that the SP-sensitive cells, such as A549 and T98G, exhibit the lowest expression of OGDH compared to other TCA cycle enzymes, associated with higher expression of affiliated pathways utilizing 2-oxoglutarate. Metabolic profiling confirmed the dependence of cellular SP reactivity on cell-specific expression of the pathways. Thus, oxidative decarboxylation of 2-oxoglutarate is significant for the interdependent homeostasis of NAD(P)H, ATP, ROS and key metabolites in various cancer cells. Assessment of cell-specific responses to OGDH inhibition is of diagnostic value for anticancer strategies.

Molecular mechanisms of the non-coenzyme action of thiamin in brain: biochemical, structural and pathway analysis.

Thiamin (vitamin B1) is a pharmacological agent boosting central metabolism through the action of the coenzyme thiamin diphosphate (ThDP). However, positive effects, including improved cognition, of high thiamin doses in neurodegeneration may be observed without increased ThDP or ThDP-dependent enzymes in brain. Here, we determine protein partners and metabolic pathways where thiamin acts beyond its coenzyme role. Malate dehydrogenase, glutamate dehydrogenase and pyridoxal kinase were identified as abundant proteins binding to thiamin- or thiazolium-modified sorbents. Kinetic studies, supported by structural analysis, revealed allosteric regulation of these proteins by thiamin and/or its derivatives. Thiamin triphosphate and adenylated thiamin triphosphate activate glutamate dehydrogenase. Thiamin and ThDP regulate malate dehydrogenase isoforms and pyridoxal kinase. Thiamin regulation of enzymes related to malate-aspartate shuttle may impact on malate/citrate exchange, responsible for exporting acetyl residues from mitochondria. Indeed, bioinformatic analyses found an association between thiamin- and thiazolium-binding proteins and the term acetylation. Our interdisciplinary study shows that thiamin is not only a coenzyme for acetyl-CoA production, but also an allosteric regulator of acetyl-CoA metabolism including regulatory acetylation of proteins and acetylcholine biosynthesis. Moreover, thiamin action in neurodegeneration may also involve neurodegeneration-related 14-3-3, DJ-1 and ß-amyloid precursor proteins identified among the thiamin- and/or thiazolium-binding proteins.

Mineralization of the connective tissue: a complex molecular process leading to age-related loss of function.

Age-related metastatic mineralization of soft tissues has been considered a passive and spontaneous process. Recent data have demonstrated that calcium salt deposition in soft tissues could be a highly regulated process. Although calcification occurs in any tissue type, vascular calcification has been of particular interest due to association with atherosclerosis, chronic kidney disease (CKD), and osteoporosis. Different mechanisms underlying calcium apatite accumulation are explored with these age-related disorders. In the case of atherosclerotic plaques, oxy-lipids trigger release of the pro-inflammatory cytokines and inflammation that activate calcification processes in aorta intimae. In CKD patients, renal failure alters the balance between calcium and phosphate levels usually regulated by fibroblast growth factor-23 (FGF23), Klotho, and vitamin D, and vascular smooth muscle cells (VSMCs) begin to explore an osteoblastosteoblast-like phenotype. Calcification could affect extracellular matrix along with VSMCs. Collagen is a major component of extracellular matrix and its modifications accumulate with age. The formation of cross-links between collagen fibers is regulated by the action of lysine hydroxylases and lysyl oxidase and could occur spontaneously. Oxidation-induced advanced glycation end products (AGEs) are a major type of spontaneous cross-links that accelerate with age and may result in tissue stiffness, problems with recycling, and potential accumulation of calcium apatite. Applying strategies for clearing the AGEs proposed by de Grey may be more difficult in the highly mineralized extracellular matrix. We performed bioinformatic analysis of the molecular pathways underlying calcification in atherosclerotic and CKD patients, signaling pathways of collagen cross-links formation, and bone mineralization, and we propose new potential targets and review drugs for calcification treatment.

On the role of the mitochondrial 2-oxoglutarate dehydrogenase complex in amino acid metabolism.

Mitochondria are tightly linked to cellular nutrient sensing, and provide not only energy, but also intermediates for the de novo synthesis of cellular compounds including amino acids. Mitochondrial metabolic enzymes as generators and/or targets of signals are therefore important players in the distribution of intermediates between catabolic and anabolic pathways. The highly regulated 2-oxoglutarate dehydrogenase complex (OGDHC) participates in glucose oxidation via the tricarboxylic acid cycle. It occupies an amphibolic branch point in the cycle, where the energy-producing reaction of the 2-oxoglutarate degradation competes with glutamate (Glu) synthesis via nitrogen incorporation into 2-oxoglutarate. To characterize the specific impact of the OGDHC inhibition on amino acid metabolism in both plant and animal mitochondria, a synthetic analog of 2-oxoglutarate, namely succinyl phosphonate (SP), was applied to living systems from different kingdoms, both in situ and in vivo. Using a high-throughput mass spectrometry-based approach, we showed that organisms possessing OGDHC respond to SP by significantly changing their amino acid pools. By contrast, cyanobacteria which lack OGDHC do not show perturbations in amino acids following SP treatment. Increases in Glu, 4-aminobutyrate and alanine represent the most universal change accompanying the 2-oxoglutarate accumulation upon OGDHC inhibition. Other amino acids were affected in a species-specific manner, suggesting specific metabolic rearrangements and substrate availability mediating secondary changes. Strong perturbation in the relative abundance of amino acids due to the OGDHC inhibition was accompanied by decreased protein content. Our results provide specific evidence of a considerable role of OGDHC in amino acid metabolism.

Up-regulation of 2-oxoglutarate dehydrogenase as a stress response.

2-Oxoglutarate dehydrogenase multienzyme complex (OGDHC) operates at a metabolic cross-road, mediating Ca(2+)- and ADP-dependent signals in mitochondria. Here, we test our hypothesis that OGDHC plays a major role in the neurotransmitter metabolism and associated stress response. This possibility was assessed using succinyl phosphonate (SP), a highly specific and efficient in vivo inhibitor of OGDHC. Animals exposed to toxicants (SP, ethanol or MnCl(2)), trauma or acute hypoxia showed intrinsic up-regulation of OGDHC in brain and heart. The known mechanism of the SP action as OGDHC inhibitor pointed to the up-regulation triggered by the enzyme impairment. The animal behavior and skeletal muscle or heart performance were tested to correlate physiology with the OGDHC regulation and associated changes in the glutamate and cellular energy status. The SP-treated animals exhibited interdependent changes in the brain OGDHC activity, glutamate level and cardiac autonomic balance, suggesting the neurotransmitter role of glutamate to be involved in the changed heart performance. Energy insufficiency after OGDHC inhibition was detectable neither in animals up to 25 mg/kg SP, nor in cell culture during 24 h incubation with 0.1 mM SP. However, in animals subjected to acute ethanol intoxication SP did evoke energy deficit, decreasing muscular strength and locomotion and increasing the narcotic sleep duration. This correlated with the SP-induced decrease in NAD(P)H levels of the ethanol-exposed neurons. Thus, we show the existence of natural mechanisms to up-regulate mammalian OGDHC in response to stress, with both the glutamate neurotransmission and energy production potentially involved in the OGDHC impact on physiological performance. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.