Creatine as a Neuroprotector: an Actor that Can Play Many Parts

Neurochemical changes in the progression of Huntington's disease: A meta-analysis of in vivo1H-MRS studies

Proton magnetic resonance spectroscopy (1H-MRS) allows measuring specific brain metabolic alterations in Huntington's disease (HD), and these metabolite profiles may serve as non-invasive biomarkers associated with disease progression. Despite this potential, previous findings are inconsistent. Accordingly, we performed a meta-analysis on available in vivo1H-MRS studies in premanifest (Pre-HD) and symptomatic HD stages (Symp-HD), and quantified neurometabolic changes relative to controls in 9 Pre-HD studies (227 controls and 188 mutation carriers) and 14 Symp-HD studies (326 controls and 306 patients). Our results indicated decreased N-acetylaspartate and creatine in the basal ganglia in both Pre-HD and Symp-HD. The overall level of myo-inositol was decreased in Pre-HD while increased in Symp-HD. Besides, Symp-HD patients showed more severe metabolism disruption than Pre-HD patients. Taken together, 1H-MRS is important for elucidating progressive metabolite changes from Pre-HD to clinical conversion; N-acetylaspartate and creatine in the basal ganglia are already sensitive at the preclinical stage and are promising biomarkers for tracking disease progression; overall myo-inositol is a possible characteristic metabolite for distinguishing HD stages.

Mini-encyclopedia of mitochondria-relevant nutraceuticals protecting health in primary and secondary care-clinically relevant 3PM innovation

Despite their subordination in humans, to a great extent, mitochondria maintain their independent status but tightly cooperate with the "host" on protecting the joint life quality and minimizing health risks. Under oxidative stress conditions, healthy mitochondria promptly increase mitophagy level to remove damaged "fellows" rejuvenating the mitochondrial population and sending fragments of mtDNA as SOS signals to all systems in the human body. As long as metabolic pathways are under systemic control and well-concerted together, adaptive mechanisms become triggered increasing systemic protection, activating antioxidant defense and repair machinery. Contextually, all attributes of mitochondrial patho-/physiology are instrumental for predictive medical approach and cost-effective treatments tailored to individualized patient profiles in primary (to protect vulnerable individuals again the health-to-disease transition) and secondary (to protect affected individuals again disease progression) care. Nutraceuticals are naturally occurring bioactive compounds demonstrating health-promoting, illness-preventing, and other health-related benefits. Keeping in mind health-promoting properties of nutraceuticals along with their great therapeutic potential and safety profile, there is a permanently growing demand on the application of mitochondria-relevant nutraceuticals. Application of nutraceuticals is beneficial only if meeting needs at individual level. Therefore, health risk assessment and creation of individualized patient profiles are of pivotal importance followed by adapted nutraceutical sets meeting individual needs. Based on the scientific evidence available for mitochondria-relevant nutraceuticals, this article presents examples of frequent medical conditions, which require protective measures targeted on mitochondria as a holistic approach following advanced concepts of predictive, preventive, and personalized medicine (PPPM/3PM) in primary and secondary care.

Review of the evidence of radioprotective potential of creatine and arginine as dietary supplements

PURPOSE

Creatine (Cr) and l-arginine are naturally occurring guanidino compounds, commonly used as ergogenic dietary supplements. Creatine and l-arginine exhibit also a number of non-energy-related features, such as antioxidant, anti-apoptotic, and anti-inflammatory properties, which contribute to their protective action against oxidative stress (OS). In this regard, there are a number of studies emphasizing the protective effect of Cr against OS, which develops in the process of aging, increased physical loads as part of athletes' workouts, as well as a number of neurological diseases and toxic effects associated with xenobiotics and UV irradiation. Against this backdrop, and since ionizing radiation causes OS in cells, leading to radiotoxicity, there is an increasing interest to understand whether Cr has the full potential to serve as an effective radioprotective agent. The extensive literature search did not provide any data on this issue. In this narrative review, we have summarized some of our own experimental data published over the last years addressing the respective radioprotective effects of Cr. Next, we have additionally reviewed the existing data on the radiomodifying effects of l-arginine presented earlier by other research groups.

CONCLUSIONS

Creatine possesses significant radioprotective potential including: (1) radioprotective effect on the survival rate of rats subjected to acute whole-body X-ray irradiation in a LD70/30 dose of 6.5 Gy, (2) radioprotective effect on the population composition of peripheral blood cells, (3) radioprotective effect on the DNA damage of peripheral blood mononuclear cells, (4) radioprotective effect on the hepatocyte nucleus-nucleolar apparatus, and (5) radioprotective effect on the brain and liver Cr-Cr kinase systems of the respective animals. Taking into account these cytoprotective, gene-protective, hepatoprotective and energy-stimulating features of Cr, as well as its significant radioprotective effect on the survival rate of rats, it can be considered as a potentially promising radioprotector for further preclinical and clinical studies. The review of the currently available data on radiomodifying effects of l-arginine has indicated its significant potential as a radioprotector, radiomitigator, and radiosensitizer. However, to prove the effectiveness of arginine (Arg) as a radioprotective agent, it appears necessary to expand and deepen the relevant preclinical studies, and, most importantly, increase the number of proof-of-concept clinical trials, which are evidently lacking as of now.

Psychiatric Manifestations in Children and Adolescents with Inherited Metabolic Diseases

Background: Inherited metabolic disorders (IEMs) can be represented in children and adolescents by psychiatric disorders. The early diagnosis of IEMs is crucial for clinical outcome and treatment. The aim of this review is to analyze the most recurrent and specific psychiatric features related to IEMs in pediatrics, based on the onset type and psychiatric phenotypes. Methods: Following the PRISMA Statement, a systematic literature review was performed using a predefined algorithm to find suitable publications in scientific databases of interest. After removing duplicates and screening titles and abstracts, suitable papers were analyzed and screened for inclusion and exclusion criteria. Finally, the data of interest were retrieved from the remaining articles. Results: The results of this study are reported by type of symptoms onset (acute and chronic) and by possible psychiatric features related to IEMs. Psychiatric phenomenology has been grouped into five main clinical manifestations: mood and anxiety disorders; schizophrenia-spectrum disorders; catatonia; eating disorders; and self-injurious behaviors. Conclusions: The inclusion of a variety of psychiatric manifestations in children and adolescents with different IEMs is a key strength of this study, which allowed us to explore the facets of seemingly different disorders in depth, avoiding possible misdiagnoses, with the related delay of early and appropriate treatments.

Ligand-Screened Cerium-Based MOF Microcapsules Promote Nerve Regeneration via Mitochondrial Energy Supply

Although mitochondria are crucial for recovery after spinal cord injury (SCI), therapeutic strategies to modulate mitochondrial metabolic energy to coordinate the immune response and nerve regeneration are lacking. Here, a ligand-screened cerium-based metal-organic framework (MOF) with better ROS scavenging and drug-loading abilities is encapsulated with polydopamine after loading creatine to obtain microcapsules (Cr/Ce@PDA nanoparticles), which reverse the energy deficits in both macrophages and neuronal cells by combining ROS scavenging and energy supplementation. It reprogrames inflammatory macrophages to the proregenerative phenotype via the succinate/HIF-1α/IL-1β signaling axis. It also promotes the regeneration and differentiation of neural cells by activating the mTOR pathway and paracrine function of macrophages. In vivo experiments further confirm the effect of the microcapsules in regulating early ROS-inflammation positive-feedback chain reactions and continuously promoting nerve regeneration. This study provides a new strategy for correcting mitochondrial energy deficiency in the immune response and nerve regeneration following SCI.

Modulation of Cellular Levels of Adenosine Phosphates and Creatine Phosphate in Cultured Primary Astrocytes

Adenosine triphosphate (ATP) is the main energy currency of all cells, while creatine phosphate (CrP) is considered as a buffer of high energy-bond phosphate that facilitates rapid regeneration of ATP from adenosine diphosphate (ADP). Astrocyte-rich primary cultures contain ATP, ADP and adenosine monophosphate (AMP) in average specific contents of 36.0 ± 6.4 nmol/mg, 2.9 ± 2.1 nmol/mg and 1.7 ± 2.1 nmol/mg, respectively, which establish an adenylate energy charge of 0.92 ± 0.04. The average specific cellular CrP level was found to be 25.9 ± 10.8 nmol/mg and the CrP/ATP ratio was 0.74 ± 0.28. The specific cellular CrP content, but not the ATP content, declined with the age of the culture. Absence of fetal calf serum for 24 h caused a partial loss in the cellular contents of both CrP and ATP, while application of creatine for 24 h doubled the cellular CrP content and the CrP/ATP ratio, but did not affect ATP levels. In glucose-deprived astrocytes, the high cellular ATP and CrP contents were rapidly depleted within minutes after application of the glycolysis inhibitor 2-deoxyglucose and the respiratory chain inhibitor antimycin A. For those conditions, the decline in CrP levels always preceded that of ATP contents. In contrast, incubation of glucose-fed astrocytes for up to 30 min with antimycin A had little effect on the high cellular ATP content, while the CrP level was significantly lowered. These data demonstrate the importance of cellular CrP for maintaining a high cellular ATP content in astrocytes during episodes of impaired ATP regeneration.

Diagnosis and Treatment of X-Linked Creatine Transporter Deficiency: Case Report and Literature Review

(1) Background: X-linked creatine transporter deficiency (CTD) (OMIM 300036) is a rare group of inherited metabolic disorders characterized by global developmental delay/intellectual disability (GDD/ID), seizures, autistic behavior, and movement disorders. Pathogenic variants in the SLC6A8 gene, located at Xq28, are causative of the disease, leading to impaired creatine transport into the brain. Supplementation with creatine and its precursors, glycine and arginine, has been attempted, yet the treatment efficacy remains controversial. (2) Methods: Here we report a de novo SLC6A8 variant in a boy aged 3 years 9 months presenting with GDD, autistic behavior, and epilepsy. Elevated urinary creatine/creatinine ratio and diminished creatine peak on brain MR spectroscopy suggested the diagnosis of CTD. Genetic sequencing revealed a de novo hemizygous frameshift variant (NM_005629: c.1136_1137del, p. Glu379ValfsTer85). Creatine supplementation therapy was initiated after definitive diagnosis. Electroencephalography and MR spectroscopy were monitored during follow-up in concurrence with neuropsychological evaluations. The clinical phenotype and treatment response of CTD were summarized by systematic view of the literature. (3) Results: In silico analysis showed this variant to be deleterious, probably interfering with substrate binding and conformational changes during creatine transport. Creatine supplementation therapy led to seizure cessation and modest cognitive improvement after half-year's treatment. (4) Conclusions: This case highlights the importance of MR spectroscopy and metabolic screening in males with GDD/ID, allowing for early diagnosis and therapeutic intervention. Mechanistic understanding and case-per-se analysis are required to enable precision treatment for the patients.

Creatine supplementation protects spatial memory and long-term potentiation against chronic restraint stress

Stress contributes to numerous psychopathologies, including memory impairment, and threatens one's well-being. It has been reported that creatine supplementation potentially influences cognitive processing. Hence, in this study, we examined the effects of creatine supplementation on memory, synaptic plasticity, and neuronal arborization in the CA1 region of the hippocampus in rats under chronic restraint stress (CRS). Thirty-two adult male Wistar rats (8 weeks old) weighing 200-250 g were randomly divided into four groups (n = 8/per group): control, stress, creatine, and stress + creatine. CRS was induced for 6 h per day for 14 days, and creatine supplementation was carried out by dissolving creatine (2 g/kg body weight per day) in the animals' drinking water for 14 days. We used the Barnes maze and shuttle box for spatial and passive avoidance memory examination. The in-vivo field potential recording and Golgi-Cox staining were also used to investigate long-term potentiation (LTP) and dendrite arborization in the CA1 pyramidal neurons. Chronic stress impaired spatial memory, dysregulated LTP parameters, and decreased the number of dendrites in the CA1 pyramidal neurons of stressed rats, and creatine supplementation modified these effects in stressed rats. It seems that creatine supplementation can improve spatial memory deficits and synaptic plasticity loss induced by CRS in hippocampal CA1 neurons, possibly by reducing the dendrite arborization damages. However, understanding its mechanism needs further investigation.

Live Cell Imaging of ATP Levels Reveals Metabolic Compartmentalization within Motoneurons and Early Metabolic Changes in FUS ALS Motoneurons

Motoneurons are one of the most energy-demanding cell types and a primary target in Amyotrophic lateral sclerosis (ALS), a debilitating and lethal neurodegenerative disorder without currently available effective treatments. Disruption of mitochondrial ultrastructure, transport, and metabolism is a commonly reported phenotype in ALS models and can critically affect survival and the proper function of motor neurons. However, how changes in metabolic rates contribute to ALS progression is not fully understood yet. Here, we utilize hiPCS-derived motoneuron cultures and live imaging quantitative techniques to evaluate metabolic rates in fused in sarcoma (FUS)-ALS model cells. We show that differentiation and maturation of motoneurons are accompanied by an overall upregulation of mitochondrial components and a significant increase in metabolic rates that correspond to their high energy-demanding state. Detailed compartment-specific live measurements using a fluorescent ATP sensor and FLIM imaging show significantly lower levels of ATP in the somas of cells carrying FUS-ALS mutations. These changes lead to the increased vulnerability of diseased motoneurons to further metabolic challenges with mitochondrial inhibitors and could be due to the disruption of mitochondrial inner membrane integrity and an increase in its proton leakage. Furthermore, our measurements demonstrate heterogeneity between axonal and somatic compartments, with lower relative levels of ATP in axons. Our observations strongly support the hypothesis that mutated FUS impacts the metabolic states of motoneurons and makes them more susceptible to further neurodegenerative mechanisms.

Neuroprotective Peptides and New Strategies for Ischemic Stroke Drug Discoveries

Ischemic stroke continues to be one of the leading causes of death and disability in the adult population worldwide. The currently used pharmacological methods for the treatment of ischemic stroke are not effective enough and require the search for new tools and approaches to identify therapeutic targets and potential neuroprotectors. Today, in the development of neuroprotective drugs for the treatment of stroke, special attention is paid to peptides. Namely, peptide action is aimed at blocking the cascade of pathological processes caused by a decrease in blood flow to the brain tissues. Different groups of peptides have therapeutic potential in ischemia. Among them are small interfering peptides that block protein-protein interactions, cationic arginine-rich peptides with a combination of various neuroprotective properties, shuttle peptides that ensure the permeability of neuroprotectors through the blood-brain barrier, and synthetic peptides that mimic natural regulatory peptides and hormones. In this review, we consider the latest achievements and trends in the development of new biologically active peptides, as well as the role of transcriptomic analysis in identifying the molecular mechanisms of action of potential drugs aimed at the treatment of ischemic stroke.

Creatine Deficiency Syndromes: Comparison of Screening Methods and Characterization of Four Novel Intronic Variants

BACKGROUND

Cerebral creatine deficiency syndromes (CCDS) are disorders affecting creatine synthesis or transport. Several methods have been developed to measure creatine and guanidinoacetate (GAA) in different body fluids including methods based on gas chromatography-mass spectrometry (GC-MS) and High-pressure liquid chromatography mass spectrometry (HPLC-MS). The diagnosis of CCDS is then confirmed by sequencing of creatine biosynthesis genes guanidinoacetate methyltransferase (GAMT) and Arginine: glycine amidinotransferase (GATM) and creatine transporter gene solute carrier family 6 member 8 (SLC6A8) or by functional enzymatic assay. The aim of the current study was to find the most reliable and accurate screening method for CCDS by comparing methods using Nuclear Magnetic Resonance spectroscopy (NMR), GC-MS and HPLC-MS. Additionally, this study was performed to estimate the prevalence of CCDS in a cohort of Egyptian patients and potentially to discover novel variants.

SUBJECTS AND METHODS

The study was conducted on 150 subjects with clinical signs and symptoms consistent with CCDS. Metabolic profiling of urine samples was performed using three techniques: 1) GC-MS 2) Ultra high-pressure (or performance) liquid chromatography - Tandem Mass Spectrometry (UHPLC- MS/MS) and 3) NMR.

RESULTS

The linearity of peak areas for creatine and GAA by UHPLC-MS/MS and NMR covered and exceeded the ranges normally found in urine. The limit of quantification and the inter-day precision results for creatine and GAA were more robust by UHPLC-MS/MS than NMR. Ten cases were identified as being positive for CCDS by our analytical approaches and underwent next generation sequencing (NGS) for GAMT, GATM and SLC6A8 genes. NGS was performed and confirmed one patient with one likely Pathogenic variant in GAMT gene: (NC_000019.10:g.1401317C > G, NP_000147.1:p.Ala54Pro). Additionally, we describe four novel intronic variants in the GATM gene: c.1043-357del and c.1043-357_1043-356insT, and were predicted to activate cryptic acceptor site with potential alteration of splicing, c.979-227G > A was found to significantly alter the Exon Splice Enhancer (ESE) xon Splice Silencer (ESS) motifs ratio and c.1042 + 262del which was found to have no implications on splicing.

CONCLUSIONS

Both UHPLC-MS/MS and NMR spectroscopy are comparable to GC-MS in screening for CCDS. Nonetheless, the UHPLC-MS/MS method had better performance than NMR spectroscopy. Additionally, Sequencing of the full length of GATM, GAMT, and SLC6A8 genes is needed to identify intronic variants that could cause CCDS via affecting splice sites.

Proton magnetic resonance spectroscopy assessment of neonatal brain metabolism during cardiopulmonary bypass surgery

Here, we report on the development and performance of a robust 3-T single-voxel proton magnetic resonance spectroscopy (¹ H MRS) experimental protocol and data analysis pipeline for quantifying brain metabolism during cardiopulmonary bypass (CPB) surgery in a neonatal porcine model, with the overall goal of elucidating primary mechanisms of brain injury associated with these procedures. The specific aims were to assess which metabolic processes can be reliably interrogated by ¹ H MRS on a 3-T clinical scanner and to provide an initial assessment of brain metabolism during deep hypothermia cardiac arrest (DHCA) surgery and recovery. Fourteen neonatal pigs underwent CPB surgery while placed in a 3-T MRI scanner for 18, 28, and 37°C DHCA studies under hyperglycemic, euglycemic, and hypoglycemic conditions. Total imaging times, including baseline measurements, circulatory arrest (CA), and recovery averaged 3 h/animal, during which 30-40 single-voxel ¹ H MRS spectra (sLASER pulse sequence, TR/TE = 2000/30 ms, 64 or 128 averages) were acquired from a 2.2-cc right midbrain voxel. ¹ H MRS at 3 T was able to reliably quantify (1) anaerobic metabolism via depletion of brain glucose and the associated build-up of lactate during CA, (2) phosphocreatine (PCr) to creatine (Cr) conversion during CA and subsequent recovery upon reperfusion, (3) a robust increase in the glutamine-to-glutamate (Gln/Glu) ratio during the post-CA recovery period, and (4) a broadening of the water peak during CA. In vivo ¹ H MRS at 3 T can reliably quantify subtle metabolic brain changes previously deemed challenging to interrogate, including brain glucose concentrations even under hypoglycemic conditions, ATP usage via the conversion of PCr to Cr, and differential changes in Glu and Gln. Observed metabolic changes during CPB surgery of a neonatal porcine model provide new insights into possible mechanisms for prevention of neuronal injury.

Neurons undergo pathogenic metabolic reprogramming in models of familial ALS

Objectives

Methods

Results

Conclusions

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Our work is the first to perform a comprehensive and quantitative analysis of intermediary metabolism in neurons in the setting of fALS causing gene products.

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Because the cardinal feature of ALS is death of motor neurons, these new studies are directly relevant to the pathogenesis of ALS.

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Our functional interrogations begin to unpack how metabolic re-wiring is induced by fALS genes and it will be very interesting, in the future, to gain insight in amino acid fueling of the TCA cycle.

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We suspect pleiotropic effects of amino acid fueling, and this may lead to very targeted therapeutic interventions.

Mitochondrial dysfunction, oxidative stress, neuroinflammation, and metabolic alterations in the progression of Alzheimer's disease: A meta-analysis of in vivo magnetic resonance spectroscopy studies

Accumulating evidence demonstrates that metabolic changes in the brain associated with neuroinflammation, oxidative stress, and mitochondrial dysfunction play an important role in the pathophysiology of mild cognitive impairment (MCI) and Alzheimer's disease (AD). However, the neural signatures associated with these metabolic alterations and underlying molecular mechanisms are still elusive. Accordingly, we reviewed the literature on in vivo human brain 1H and 31P-MRS studies and use meta-analyses to identify patterns of brain metabolic alterations in MCI and AD. 40 and 39 studies on MCI and AD, respectively, were classified according to brain regions. Our results indicate decreased N-acetyl aspartate and creatine but increased myo-inositol levels in both MCI and AD, decreased glutathione level in MCI as well as disrupted energy metabolism in AD. In addition, the hippocampus shows the strongest alterations in most of these metabolites. This meta-analysis also illustrates progressive metabolite alterations from MCI to AD. Taken together, it suggests that 1) neuroinflammation and oxidative stress may occur in the early stages of AD, and likely precede neuron loss in its progression; 2) the hippocampus is a sensitive region of interest for early diagnosis and monitoring the response of interventions; 3) targeting bioenergetics associated with neuroinflammation/oxidative stress is a promising approach for treating AD.

Nutritional approaches to counter performance constraints in high-level sports competition

New Findings

What is the topic of this review?

The nutritional strategies that athletes use during competition events to optimize performance and the reasons they use them.

What advances does it highlight?

A range of nutritional strategies can be used by competitive athletes, alone or in combination, to address various event‐specific factors that constrain event performance. Evidence for such practices is constantly evolving but must be combined with understanding of the complexities of real‐life sport for optimal implementation.

Abstract

High‐performance athletes share a common goal despite the unique nature of their sport: to pace or manage their performance to achieve the highest sustainable outputs over the duration of the event. Periodic or sustained decline in the optimal performance of event tasks, involves an interplay between central and peripheral phenomena that can often be reduced or delayed in onset by nutritional strategies. Contemporary nutrition practices undertaken before, during or between events include strategies to ensure the availability of limited muscle fuel stores. This includes creatine supplementation to increase muscle phosphocreatine content and consideration of the type, amount and timing of dietary carbohydrate intake to optimize muscle and liver glycogen stores or to provide additional exogenous substrate. Although there is interest in ketogenic low‐carbohydrate high‐fat diets and exogenous ketone supplements to provide alternative fuels to spare muscle carbohydrate use, present evidence suggests a limited utility of these strategies. Mouth sensing of a range of food tastants (e.g., carbohydrate, quinine, menthol, caffeine, fluid, acetic acid) may provide a central nervous system derived boost to sports performance. Finally, despite decades of research on hypohydration and exercise capacity, there is still contention around their effect on sports performance and the best guidance around hydration for sporting events. A unifying model proposes that some scenarios require personalized fluid plans while others might be managed by an ad hoc approach (ad libitum or thirst‐driven drinking) to fluid intake.

Creatine transporter deficiency impairs stress adaptation and brain energetics homeostasis

The creatine transporter (CrT) maintains brain creatine (Cr) levels, but the effects of its deficiency on energetics adaptation under stress remain unclear. There are also no effective treatments for CrT deficiency, the second most common cause of X-linked intellectual disabilities. Herein, we examined the consequences of CrT deficiency in brain energetics and stress-adaptation responses plus the effects of intranasal Cr supplementation. We found that CrT-deficient (CrT^–/y) mice harbored dendritic spine and synaptic dysgenesis. Nurtured newborn CrT^–/y mice maintained baseline brain ATP levels, with a trend toward signaling imbalance between the p-AMPK/autophagy and mTOR pathways. Starvation elevated the signaling imbalance and reduced brain ATP levels in P3 CrT^–/y mice. Similarly, CrT^–/y neurons and P10 CrT^–/y mice showed an imbalance between autophagy and mTOR signaling pathways and greater susceptibility to cerebral hypoxia-ischemia and ischemic insults. Notably, intranasal administration of Cr after cerebral ischemia increased the brain Cr/N-acetylaspartate ratio, partially averted the signaling imbalance, and reduced infarct size more potently than intraperitoneal Cr injection. These findings suggest important functions for CrT and Cr in preserving the homeostasis of brain energetics in stress conditions. Moreover, intranasal Cr supplementation may be an effective treatment for congenital CrT deficiency and acute brain injury.

DNMT1 mutations leading to neurodegeneration paradoxically reflect on mitochondrial metabolism

ADCA-DN and HSN-IE are rare neurodegenerative syndromes caused by dominant mutations in the replication foci targeting sequence (RFTS) of the DNA methyltransferase 1 (DNMT1) gene. Both phenotypes resemble mitochondrial disorders, and mitochondrial dysfunction was first observed in ADCA-DN. To explore mitochondrial involvement, we studied the effects of DNMT1 mutations in fibroblasts from four ADCA-DN and two HSN-IE patients. We documented impaired activity of purified DNMT1 mutant proteins, which in fibroblasts results in increased DNMT1 amount. We demonstrated that DNMT1 is not localized within mitochondria, but it is associated with the mitochondrial outer membrane. Concordantly, mitochondrial DNA failed to show meaningful CpG methylation. Strikingly, we found activated mitobiogenesis and OXPHOS with significant increase of H₂O₂, sharply contrasting with a reduced ATP content. Metabolomics profiling of mutant cells highlighted purine, arginine/urea cycle and glutamate metabolisms as the most consistently altered pathways, similar to primary mitochondrial diseases. The most severe mutations showed activation of energy shortage AMPK-dependent sensing, leading to mTORC1 inhibition. We propose that DNMT1 RFTS mutations deregulate metabolism lowering ATP levels, as a result of increased purine catabolism and urea cycle pathways. This is associated with a paradoxical mitochondrial hyper-function and increased oxidative stress, possibly resulting in neurodegeneration in non-dividing cells.

Sex-Based Impact of Creatine Supplementation on Depressive Symptoms, Brain Serotonin and SSRI Efficacy in an Animal Model of Treatment-Resistant Depression

Background: Rates of major depressive disorder (MDD) increase with living at altitude. In our model, rats housed at moderate altitude (in hypobaric hypoxia) exhibit increased depression-like behavior, altered brain serotonin and a lack of antidepressant response to most selective serotonin reuptake inhibitors (SSRIs). A forebrain deficit in the bioenergetic marker creatine is noted in people living at altitude or with MDD. Methods: Rats housed at 4500 ft were given dietary creatine monohydrate (CRMH, 4% w/w, 5 weeks) vs. un-supplemented diet, and impact on depression-like behavior, brain bioenergetics, serotonin and SSRI efficacy assessed. Results: CRMH significantly improved brain creatine in a sex-based manner. At altitude, CRMH increased serotonin levels in the female prefrontal cortex and striatum but reduced male striatal and hippocampal serotonin. Dietary CRMH was antidepressant in the forced swim test and anti-anhedonic in the sucrose preference test in only females at altitude, with motor behavior unchanged. CRMH improved fluoxetine efficacy (20 mg/kg) in only males at altitude: CRMH + SSRI significantly improved male striatal creatine and serotonin vs. CRMH alone. Conclusions: Dietary CRMH exhibits sex-based efficacy in resolving altitude-related deficits in brain biomarkers, depression-like behavior and SSRI efficacy, and may be effective clinically for SSRI-resistant depression at altitude. This is the first study to link CRMH treatment to improving brain serotonin.

Temporal trends in dietary creatine intake from 1999 to 2018: an ecological study with 89,161 participants

Introduction

We described here the annual variations in mean dietary creatine intake from 1999 to 2018 in U.S. children and adults using National Health and Nutrition Examination Survey (NHANES) database.

Methods

Dietary intake information from ten consecutive rounds of NHANES (from 1999 to 2000 to 2017–2018) was extracted for a total of 89,161 respondents aged 0–85 years. Individual values for total grams of creatine consumed per day were computed using the average amount of creatine (3.88 g/kg) across all creatine-containing food sources.

Results

The average daily intake of creatine across the entire sample was 0.70 ± 0.78 g (95% confidence interval [CI], from 0.69 to 0.71) and 13.1 ± 16.5 mg/kg body weight (95% CI, from 13.0 to 13.2). A significant negative trend for dietary creatine intake was found in infants (r = − 0.019; P = 0.042), and children and adolescents (r = − 0.024; P < 0.001).

Conclusions

Our findings suggest a variation in dietary creatine intake in the U.S. population during the past 20 years, with young persons tend to consume fewer grams of creatine per day from 1999 onwards. Long-running studies are highly warranted to assess possible health consequences of variable creatine intake in human nutrition.

Creatine Levels in Patients with Phenylketonuria and Mild Hyperphenylalaninemia: A Pilot Study

Background: Creatine (Cr) levels are strongly dependent on diets, including animal-derived proteins. Cr is an important metabolite as it represents a source of stored energy to support physical performance and potentially sustain positive effects such as improving memory or intelligence. This study was planned to assess Cr levels in PKU children adhering to a diet low in phenylalanine (Phe) content and compared with those of children with mild hyperphenylalaninemia (MHP) on a free diet. Methods: This retrospective pilot study analyzed Cr levels from Guthrie cards in 25 PKU and 35 MHP subjects. Anthropomorphic and nutritional data of the study populations were assessed, compared and correlated. Results: Cr levels of PKU subjects were significantly lower than those of MHP subjects and correlated to the low intake of animal proteins. Although no deficiencies in PKU subjects were identified, PKU subjects were found to have a 26-fold higher risk of displaying Cr levels <25° percentile than MHP counterparts. Conclusions: This pilot study suggests that Cr levels might be concerningly low in PKU children adhering to a low-Phe diet. Confirmatory studies are needed in PKU patients of different age groups to assess Cr levels and the potential benefits on physical and intellectual performance of Cr supplementation.

Metabolic Basis of Creatine in Health and Disease: A Bioinformatics-Assisted Review

Creatine (Cr) is a ubiquitous molecule that is synthesized mainly in the liver, kidneys, and pancreas. Most of the Cr pool is found in tissues with high-energy demands. Cr enters target cells through a specific symporter called Na⁺/Cl⁻-dependent Cr transporter (CRT). Once within cells, creatine kinase (CK) catalyzes the reversible transphosphorylation reaction between [Mg²⁺:ATP⁴⁻]²⁻ and Cr to produce phosphocreatine (PCr) and [Mg²⁺:ADP³⁻]⁻. We aimed to perform a comprehensive and bioinformatics-assisted review of the most recent research findings regarding Cr metabolism. Specifically, several public databases, repositories, and bioinformatics tools were utilized for this endeavor. Topics of biological complexity ranging from structural biology to cellular dynamics were addressed herein. In this sense, we sought to address certain pre-specified questions including: (i) What happens when creatine is transported into cells? (ii) How is the CK/PCr system involved in cellular bioenergetics? (iii) How is the CK/PCr system compartmentalized throughout the cell? (iv) What is the role of creatine amongst different tissues? and (v) What is the basis of creatine transport? Under the cellular allostasis paradigm, the CK/PCr system is physiologically essential for life (cell survival, growth, proliferation, differentiation, and migration/motility) by providing an evolutionary advantage for rapid, local, and temporal support of energy- and mechanical-dependent processes. Thus, we suggest the CK/PCr system acts as a dynamic biosensor based on chemo-mechanical energy transduction, which might explain why dysregulation in Cr metabolism contributes to a wide range of diseases besides the mitigating effect that Cr supplementation may have in some of these disease states.

Role of Creatine in the Heart: Health and Disease

Creatine is a key player in heart contraction and energy metabolism. Creatine supplementation (throughout the paper, only supplementation with creatine monohydrate will be reviewed, as this is by far the most used and best-known way of supplementing creatine) increases creatine content even in the normal heart, and it is generally safe. In heart failure, creatine and phosphocreatine decrease because of decreased expression of the creatine transporter, and because phosphocreatine degrades to prevent adenosine triphosphate (ATP) exhaustion. This causes decreased contractility reserve of the myocardium and correlates with left ventricular ejection fraction, and it is a predictor of mortality. Thus, there is a strong rationale to supplement with creatine the failing heart. Pending additional trials, creatine supplementation in heart failure may be useful given data showing its effectiveness (1) against specific parameters of heart failure, and (2) against the decrease in muscle strength and endurance of heart failure patients. In heart ischemia, the majority of trials used phosphocreatine, whose mechanism of action is mostly unrelated to changes in the ergogenic creatine-phosphocreatine system. Nevertheless, preliminary data with creatine supplementation are encouraging, and warrant additional studies. Prevention of cardiac toxicity of the chemotherapy compounds anthracyclines is a novel field where creatine supplementation may also be useful. Creatine effectiveness in this case may be because anthracyclines reduce expression of the creatine transporter, and because of the pleiotropic antioxidant properties of creatine. Moreover, creatine may also reduce concomitant muscle damage by anthracyclines.

Common questions and misconceptions about creatine supplementation: what does the scientific evidence really show?

Supplementing with creatine is very popular amongst athletes and exercising individuals for improving muscle mass, performance and recovery. Accumulating evidence also suggests that creatine supplementation produces a variety of beneficial effects in older and patient populations. Furthermore, evidence-based research shows that creatine supplementation is relatively well tolerated, especially at recommended dosages (i.e. 3-5 g/day or 0.1 g/kg of body mass/day). Although there are over 500 peer-refereed publications involving creatine supplementation, it is somewhat surprising that questions regarding the efficacy and safety of creatine still remain. These include, but are not limited to: 1. Does creatine lead to water retention? 2. Is creatine an anabolic steroid? 3. Does creatine cause kidney damage/renal dysfunction? 4. Does creatine cause hair loss / baldness? 5. Does creatine lead to dehydration and muscle cramping? 6. Is creatine harmful for children and adolescents? 7. Does creatine increase fat mass? 8. Is a creatine 'loading-phase' required? 9. Is creatine beneficial for older adults? 10. Is creatine only useful for resistance / power type activities? 11. Is creatine only effective for males? 12. Are other forms of creatine similar or superior to monohydrate and is creatine stable in solutions/beverages? To answer these questions, an internationally renowned team of research experts was formed to perform an evidence-based scientific evaluation of the literature regarding creatine supplementation.

Diagnostic and Pharmacological Potency of Creatine in Post-Viral Fatigue Syndrome

Post-viral fatigue syndrome (PVFS) is a widespread chronic neurological disease with no definite etiological factor(s), no actual diagnostic test, and no approved pharmacological treatment, therapy, or cure. Among other features, PVFS could be accompanied by various irregularities in creatine metabolism, perturbing either tissue levels of creatine in the brain, the rates of phosphocreatine resynthesis in the skeletal muscle, or the concentrations of the enzyme creatine kinase in the blood. Furthermore, supplemental creatine and related guanidino compounds appear to impact both patient- and clinician-reported outcomes in syndromes and maladies with chronic fatigue. This paper critically overviews the most common disturbances in creatine metabolism in various PVFS populations, summarizes human trials on dietary creatine and creatine analogs in the syndrome, and discusses new frontiers and open questions for using creatine in a post-COVID-19 world.

Investigation of the detoxification effect of licorice on Semen Strychni-induced acute toxicity in rats using a HPLC-Q-TOF/MS-based metabolomics approach

Semen Strychni, a traditional Chinese medicine (TCM), has been widely used to treat paraplegia, facial nerve palsy and myasthenia gravis. However, its clinical application is greatly limited due to its fatal toxicity. To investigate the acute toxicity of Semen Strychni and the detoxification effect of licorice, a high-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF/MS) based urinary metabolomics method was developed in this study. After intraperitoneal injection to rats with Semen Strychni extract, the serum biochemical indexes were changed significantly, the liver and kidney showed severe necrosis and edema. Then the poisoned rat model was subsequently used for metabolomics research. Through principal component analysis (PCA) and orthogonal partial least squares-discriminant analysis (OPLS-DA), we finally identified 19 endogenous differential metabolites involved in amino acid metabolism, glycerophospholipid metabolism, tricarboxylic acid (TCA) cycle, oxidative stress and energy metabolism. In addition, 4 exogenous compounds from Semen Strychni (3 prototypes and 1 metabolite) were also identified in the present study. Results showed that the alterations of 23 compounds caused by Semen Strychni were significantly reversed after licorice treatment, which indicated that restoring the endogenous metabolic disorder and accelerating the metabolism of the main toxic components might be the possible detoxification mechanisms of licorice. This study may provide an integral understanding for the acute toxicity of Semen Strychni and the detoxification effect of licorice, thereby contributing to the clinical use of Semen Strychni and licorice.

Gut Microbiota Approach-A New Strategy to Treat Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by neuronal loss and dysfunction of dopaminergic neurons located in the substantia nigra, which contain a variety of misfolded α-synuclein (α-syn). Medications that increase or substitute for dopamine can be used for the treatment of PD. Recently, numerous studies have shown gut microbiota plays a crucial role in regulating and maintaining multiple aspects of host physiology including host metabolism and neurodevelopment. In this review article, the role of gut microbiota in the etiological mechanism of PD will be reviewed. Furthermore, we discussed current pharmaceutical medicine-based methods to prevent and treat PD, followed by describing specific strains that affect the host brain function through the gut-brain axis. We explained in detail how gut microbiota directly produces neurotransmitters or regulate the host biosynthesis of neurotransmitters. The neurotransmitters secreted by the intestinal lumen bacteria may induce epithelial cells to release molecules that, in turn, can regulate neural signaling in the enteric nervous system and subsequently control brain function and behavior through the brain-gut axis. Finally, we proved that the microbial regulation of the host neuronal system. Endogenous α-syn can be transmitted long distance and bidirectional between ENS and brain through the circulatory system which gives us a new option that the possibility of altering the community of gut microbiota in completely new medication option for treating PD.

Creatine and multiple sclerosis

Multiple sclerosis (MS) is a complex and debilitating neurodegenerative disease, with unknown cause(s), unpredictable prognosis, and rather limited treatment options. MS is often accompanied by various metabolic disturbances, with impaired creatine metabolism may play a role in its pathogenesis and the clinical course of the disease. This review summarizes human trials describing alterations in creatine levels in the nervous system and other tissues during MS, affects how certain medications for MS affect brain creatine concentrations, and discusses a possible demand for exogenous creatine as an adjunct therapeutic agent in the management of MS. Creatine metabolism seems to be dysfunctional in MS, indicating a low metabolic state of the brain and other relevant organs in this unpredictable demyelinating disease. A disease-driven brain creatine deficit could be seen as a distinctive pathological facet of severe MS that might be approached with targeted therapies in aim to restore creatine homeostasis.

Withdrawal Effects Following Methionine Exposure in Adult Zebrafish

Methionine (Met) has important functions for homeostasis of various species, including zebrafish. However, the increased levels of this amino acid in plasma, a condition known as hypermethioninemia, can lead to cell alterations. Met is crucial for the methylation process and its excesses interfere with the cell cycle, an effect that persists even after the removal of this amino acid. Some conditions may lead to a transient increase of this amino acid with unexplored persistent effects of Met exposure. In the present study, we investigated the behavioral and neurochemical effects after the withdrawal of Met exposure. Zebrafish were divided into two groups: control and Met-treated group (3 mM) for 7 days and after maintained for 8 days in tanks containing only water. In the eighth day post-exposure, we evaluated locomotion, anxiety, aggression, social interaction, and memory, as well as oxidative stress parameters, amino acid, and neurotransmitter levels in the zebrafish brain. Our results showed that 8 days after Met exposure, the treated group showed decreased locomotion and aggressive responses, as well as impaired aversive memory. The Met withdrawal did not change thiobarbituric acid reactive substances, reactive oxygen species, and nitrite levels; however, we observed a decrease in antioxidant enzymes superoxide dismutase, catalase, and total thiols. Epinephrine and cysteine levels were decreased after the Met withdrawal whereas carnitine and creatine levels were elevated. Our findings indicate that a transient increase in Met causes persistent neurotoxicity, observed by behavioral and cognitive changes after Met withdrawal and that the mechanisms underlying these effects are related to changes in antioxidant system, amino acid, and neurotransmitter levels.

Proton Magnetic Resonance Spectroscopy in Common Dementias-Current Status and Perspectives

Dementia occurs mainly in the elderly and is associated with cognitive decline and impairment of activities of daily living. The most common forms of dementia are Alzheimer's disease (AD), vascular dementia (VD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD). To date, there are no causal options for therapy, but drug and non-drug treatments can positively modulate the course of the disease. Valid biomarkers are needed for the earliest possible and reliable diagnosis, but so far, such biomarkers have only been established for AD and require invasive and expensive procedures. In this context, proton magnetic resonance spectroscopy (¹H-MRS) provides a non-invasive and widely available technique for investigating the biochemical milieu of brain tissue in vivo. Numerous studies have been conducted for AD, but for VD, DLB, and FTD the number of studies is limited. Nevertheless, MRS can detect measurable metabolic alterations in common dementias. However, most of the studies conducted are too heterogeneous to assess the potential use of MRS technology in clinical applications. In the future, technological advances may increase the value of MRS in dementia diagnosis and treatment. This review summarizes the results of MRS studies conducted in common dementias and discusses the reasons for the lack of transfer into clinical routine.

Studies on Protection of Astaxanthin from Oxidative Damage Induced by H2O2 in RAW 264.7 Cells Based on 1H NMR Metabolomics

Astaxanthin (AST) is a fat-soluble and non-vitamin A source of carotenoid that can quench reactive oxygen species and it has strong antioxidant and anti-inflammatory abilities. Herein, we have used H₂O₂ to establish a model of oxidative damage to RAW 264.7 cells and cells treated with vitamin C as the positive control group. The changes in metabolome were examined using ¹H NMR and the results demonstrated that H₂O₂ treatment and various metabolic pathways such as amino acid, glucose, and glycerolipid metabolism were downregulated, which in turn affected citric acid cycle and energy status. AST could reverse downregulation of some of these metabolic pathways to a certain extent, and reduce cellular oxidative stress and death. The AST group differed from the vitamin C group in regulating d-glutamine, d-glutamic acid, pyruvate, and glycerolipid metabolism. The experimental results help to further understand the antioxidant effects of AST.

Cross-talk between guanidinoacetate neurotoxicity, memory and possible neuroprotective role of creatine

Guanidinoacetate Methyltransferase deficiency is an inborn error of metabolism that results in decreased creatine and increased guanidinoacetate (GAA) levels. Patients present neurological symptoms whose mechanisms are unclear. We investigated the effects of an intrastriatal administration of 10 μM of GAA (0.02 nmol/striatum) on energy metabolism, redox state, inflammation, glutamate homeostasis, and activities/immunocontents of acetylcholinesterase and Na⁺,K⁺-ATPase, as well as on memory acquisition. The neuroprotective role of creatine was also investigated. Male Wistar rats were pretreated with creatine (50 mg/kg) or saline for 7 days underwenting stereotactic surgery. Forty-eight hours after surgery, the animals (then sixty-days-old) were divided into groups: Control, GAA, GAA + Creatine, and Creatine. Experiments were performed 30 min after intrastriatal infusion. GAA decreased SDH, complexes II and IV activities, and ATP levels, but had no effect on mitochondrial mass/membrane potential. Creatine totally prevented SDH and complex II, and partially prevented COX and ATP alterations. GAA increased dichlorofluorescein levels and decreased superoxide dismutase and catalase activities. Creatine only prevented catalase and dichlorofluorescein alterations. GAA increased cytokines, nitrites levels and acetylcholinesterase activity, but not its immunocontent. Creatine prevented such effects, except nitrite levels. GAA decreased glutamate uptake, but had no effect on the immunocontent of its transporters. GAA decreased Na⁺,K⁺-ATPase activity and increased the immunocontent of its α3 subunit. The performance on the novel object recognition task was also impaired. Creatine partially prevented the changes in glutamate uptake and Na⁺,K⁺-ATPase activity, and completely prevented the memory impairment. This study helps to elucidate the protective effects of creatine against the damage caused by GAA.