Depletion of creatine phosphagen energetics with a covalent creatine kinase inhibitor.

Creatine kinases (CKs) provide local ATP production in periods of elevated energetic demand, such as during rapid anabolism and growth. Thus, creatine energetics has emerged as a major metabolic liability in many rapidly proliferating cancers. Whether CKs can be targeted therapeutically is unknown because no potent or selective CK inhibitors have been developed. Here we leverage an active site cysteine present in all CK isoforms to develop a selective covalent inhibitor of creatine phosphagen energetics, CKi. Using deep chemoproteomics, we discover that CKi selectively engages the active site cysteine of CKs in cells. A co-crystal structure of CKi with creatine kinase B indicates active site inhibition that prevents bidirectional phosphotransfer. In cells, CKi and its analogs rapidly and selectively deplete creatine phosphate, and drive toxicity selectively in CK-dependent acute myeloid leukemia. Finally, we use CKi to uncover an essential role for CKs in the regulation of proinflammatory cytokine production in macrophages.

Antenatal creatine supplementation reduces persistent fetal lung inflammation and oxidative stress in an ovine model of chorioamnionitis.

Chorioamnionitis is a common antecedent of preterm birth and induces inflammation and oxidative stress in the fetal lungs. Reducing inflammation and oxidative stress in the fetal lungs may improve respiratory outcomes in preterm infants. Creatine is an organic acid with known anti-inflammatory and antioxidant properties. The objective of the study was to evaluate the efficacy of direct fetal creatine supplementation to reduce inflammation and oxidative stress in fetal lungs arising from an in utero proinflammatory stimulus. Fetal lambs (n = 51) were instrumented at 90 days gestation to receive a continuous infusion of creatine monohydrate (6 mg·kg-1·h-1) or saline for 17 days. Maternal chorioamnionitis was induced with intra-amniotic lipopolysaccharide (LPS; 1 mg, O55:H6) or saline 7 days before delivery at 110 days gestation. Tissue creatine content was assessed with capillary electrophoresis, and inflammatory markers were analyzed with Luminex Magpix and immunohistochemistry. Oxidative stress was measured as the level of protein thiol oxidation. The effects of LPS and creatine were analyzed using a two-way ANOVA. Fetal creatine supplementation increased lung creatine content by 149% (PCr < 0.0001) and had no adverse effects on lung morphology. LPS-exposed groups showed increased levels of interleukin-8 in the bronchoalveolar lavage (PLPS < 0.0001) and increased levels of CD45+ leukocytes (PLPS < 0.0001) and MPO+ (PLPS < 0.0001) cells in the lung parenchyma. Creatine supplementation significantly reduced the levels of CD45+ (PCr = 0.045) and MPO+ cells (PCr = 0.012) in the lungs and reduced thiol oxidation in plasma (PCr < 0.01) and lung tissue (PCr = 0.02). In conclusion, fetal creatine supplementation reduced markers of inflammation and oxidative stress in the fetal lungs arising from chorioamnionitis.NEW & NOTEWORTHY We evaluated the effect of antenatal creatine supplementation to reduce pulmonary inflammation and oxidative stress in the fetal lamb lungs arising from lipopolysaccharide (LPS)-induced chorioamnionitis. Fetal creatine supplementation increased lung creatine content and had no adverse effects on systemic fetal physiology and overall lung architecture. Importantly, fetuses that received creatine had significantly lower levels of inflammation and oxidative stress in the lungs, suggesting an anti-inflammatory and antioxidant benefit of creatine.

Creatine supplementation and resistance training to preserve muscle mass and attenuate cancer progression (CREATINE-52): a protocol for a double-blind randomized controlled trial.

BACKGROUND: Muscle mass is important for metastatic prostate cancer survival and quality of life (QoL). The backbone of treatment for men with metastatic castration sensitive prostate cancer (mCSPC) is androgen deprivation therapy (ADT) with an androgen signaling inhibitor. ADT is an effective cancer treatment, but it facilitates significant declines in muscle mass and adverse health outcomes important to mCSPC survivors, such as fatigue, and reductions in physical function, independence, insulin sensitivity, and QoL. In non-metastatic CSPC survivors, resistance training (RT) preserves muscle mass and improves these related health outcomes, but the biggest barrier to RT in CSPC survivors of all stages is fatigue. Creatine monohydrate supplementation coupled with RT (Cr + RT) may address this barrier since creatine plays a critical role in energy metabolism. Cr + RT in cancer-free older adults and other clinical populations improves muscle mass and related health outcomes. Evidence also suggests that creatine supplementation can complement cancer treatment. Thus, Cr + RT is a strategy that addresses gaps in survivorship needs of people with mCSPC. The purpose of this parallel, double-blind randomized controlled trial is to test the effects of 52-weeks of Cr + RT compared with placebo (PLA) and RT (PLA + RT) on muscle mass, other related health outcomes, and markers of cancer progression. METHODS: We will carry out this trial with our team's established, effective, home-based, telehealth RT program in 200 mCSPC survivors receiving ADT, and evaluate outcomes at baseline, 24-, and 52-weeks. RT will occur twice weekly with elastic resistance bands, and an established creatine supplementation protocol will be used for supplementation delivery. Our approach addresses a major facilitator to RT in mCSPC survivors, a home-based RT program, while utilizing a supervised model for safety. DISCUSSION: Findings will improve delivery of comprehensive survivorship care by providing a multicomponent, patient-centered lifestyle strategy to preserve muscle mass, improve health outcomes, and complement cancer treatment (NCT06112990).

No additive effect of creatine, caffeine, and sodium bicarbonate on intense exercise performance in endurance-trained individuals.

BACKGROUND: Athletes commonly use creatine, caffeine, and sodium bicarbonate for performance enhancement. While their isolated effects are well-described, less is known about their potential additive effects. METHODS: Following a baseline trial, we randomized 12 endurance-trained males (age: 25 ± 5 years, VO2max: 56.7 ± 4.6 mL kg-1 min-1; mean ± SD) and 11 females (age: 25 ± 3 years, VO2max: 50.2 ± 3.4 mL kg-1 min-1) to 5 days of creatine monohydrate (0.3 g kg-1 per day) or placebo loading, followed by a daily maintenance dose (0.04 g kg-1) throughout the study. After the loading period, subjects completed four trials in randomized order where they ingested caffeine (3 mg kg-1), sodium bicarbonate (0.3 g kg-1), placebo, or both caffeine and sodium bicarbonate before a maximal voluntary contraction (MVC), 15-s sprint, and 6-min time trial. RESULTS: Compared to placebo, mean power output during 15-s sprint was higher following loading with creatine than placebo (+34 W, 95% CI: 10 to 58, p = 0.008), but with no additional effect of caffeine (+10 W, 95% CI: -7 to 24, p = 0.156) or sodium bicarbonate (+5 W, 95% CI: -4 to 13, p = 0.397). Mean power output during 6-min time trial was higher with caffeine (+12 W, 95% CI: 5 to 18, p = 0.001) and caffeine + sodium bicarbonate (+8 W, 95% CI: 0 to 15, p = 0.038), whereas sodium bicarbonate (-1 W, 95% CI: -7 to 6, p = 0.851) and creatine (-6 W, 95% CI: -15 to 4, p = 0.250) had no effects. CONCLUSION: While creatine and caffeine can enhance sprint- and time trial performance, respectively, these effects do not seem additive. Therefore, supplementing with either creatine or caffeine appears sufficient to enhance sprint or short intense exercise performance.

Short term creatine loading improves strength endurance even without changing maximal strength, RPE, fatigue index, blood lactate, and mode state.

Creatine is consumed by athletes to increase strength and gain muscle. The aim of this study was to evaluate the effects of creatine supplementation on maximal strength and strength endurance. Twelve strength-trained men (25.2 ± 3.4 years) supplemented with 20 g Creatina + 10g maltodextrin or placebo (20g starch + 10g maltodextrin) for five days in randomized order. Maximal strength and strength endurance (4 sets 70% 1RM until concentric failure) were determined in the bench press. In addition, blood lactate, rate of perceived effort, fatigue index, and mood state were evaluated. All measurements were performed before and after the supplementation period. There were no significant changing in maximal strength, blood lactate, RPE, fatigue index, and mood state in either treatment. However, the creatine group performed more repetitions after the supplementation (Cr: Δ = +3.4 reps, p = 0.036, g = 0.53; PLA: Δ = +0.3reps, p = 0.414, g = 0.06), and higher total work (Cr: Δ = +199.5au, p = 0.038, g = 0.52; PLA: Δ = +26.7au, p = 0.402, g = 0.07). Creatine loading for five days allowed the subjects to perform more repetitions, resulting in greater total work, but failed to change the maximum strength.

Guanidinoacetate (GAA) is a potent GABAA receptor GABA mimetic: Implications for neurological disease pathology.

Impairment of excretion and enzymatic processing of nitrogen, for example, because of liver or kidney failure, or with urea cycle and creatine synthesis enzyme defects, surprisingly leads to primarily neurologic symptoms, yet the exact mechanisms remain largely mysterious. In guanidinoacetate N-methyltransferase (GAMT) deficiency, the guanidino compound guanidinoacetate (GAA) increases dramatically, including in the cerebrospinal fluid (CSF), and has been implicated in mediating the neurological symptoms in GAMT-deficient patients. GAA is synthesized by arginine-glycine amidinotransferase (AGAT), a promiscuous enzyme that not only transfers the amidino group from arginine to glycine, but also to primary amines in, for example, GABA and taurine to generate γ-guanidinobutyric acid (γ-GBA) and guanidinoethanesulfonic acid (GES), respectively. We show that GAA, γ-GBA, and GES share structural similarities with GABA, evoke GABAA receptor (GABAA R) mediated currents (whereas creatine [methylated GAA] and arginine failed to evoke discernible currents) in cerebellar granule cells in mouse brain slices and displace the high-affinity GABA-site radioligand [3 H]muscimol in total brain homogenate GABAA Rs. While γ-GBA and GES are GABA agonists and displace [3 H]muscimol (EC50 /IC50 between 10 and 40 µM), GAA stands out as particularly potent in both activating GABAA Rs (EC50 ~6 µM) and also displacing the GABAA R ligand [3 H]muscimol (IC50 ~3 µM) at pathophysiologically relevant concentrations. These findings stress the role of substantially elevated GAA as a primary neurotoxic agent in GAMT deficiency and we discuss the potential role of GAA in arginase (and creatine transporter) deficiency which show a much more modest increase in GAA concentrations yet share the unique hyperexcitability neuropathology with GAMT deficiency. We conclude that orthosteric activation of GABAA Rs by GAA, and potentially other GABAA R mimetic guanidino compounds (GCs) like γ-GBA and GES, interferes with normal inhibitory GABAergic neurotransmission which could mediate, and contribute to, neurotoxicity.

Effects of creatine and caffeine ingestion in combination on exercise performance: A systematic review.

Creatine (CRE) and caffeine (CAF) have been used as ergogenic aids to improve exercise performance. The present study reviewed the current evidence supporting the additional use of CAF intake during or after the CRE loading on exercise performance. The search was carried out in eight databases, with the methodological quality of the studies assessed via the QualSyst tool. From ten studies that met the criteria for inclusion, six had strong, three moderate, and one weak methodological quality. CAF was ingested ∼1 h before the performance trial (5-7 mg.kg-1) after a CRE loading period (5-6 days with 0.3 g.kg-1.d-1) in five studies, with the combination CAF + CRE providing additional ergogenic effect compared to CRE alone in three of these studies. Furthermore, CAF was ingested daily during the CRE loading protocol in five studies, with CAF showing additive benefits compared to CRE alone only in one study (3 g.d-1 of CRE during 3 days + 6 mg.kg-1 of CAF for 3 days). The combination CAF + CRE seems to provide additional benefits to exercise performance when CAF is acutely ingested after a CRE loading. There is, however, no apparent benefit in ingesting CAF during a CRE loading period.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2021.2007470.

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.

In ovo feeding of creatine monohydrate increases performances of hatching and development in breeder chicks.

The current investigation was conducted to test the potential effects of in ovo feeding of creatine monohydrate (CMH) on hatchability, embryonic mortality, hatching weight, and development of heart and gastrointestinal tract (main organs and regions) of breeder chick embryos. Rhode Island Red fertile eggs were randomly distributed into seven experimental treatments: untreated egg (control), a sterile buffered solution (0.50% NaCl), and five solutions containing increased levels of CMH (0.50, 1.00, 1.50, and 2.00%) + 0.50% NaCl, being separated in four groups/replicates (three with 15 eggs and one with 16 eggs), totaling 61 eggs/treatment and a total of 427 fertile eggs used. All-in ovo injected groups with CMH decreased the hatchability and increased the intermediary embryonic mortality. At hatching, all-in ovo injected groups with CMH also increased the hatching weight and stimulated the development of the heart and the total length of the gastrointestinal tract, especially important organs for digestion of nutrients (yolk sac, pro-ventricle and gizzard) and regions for nutrient absorption (jejunum + ileum and colon + rectum). Conclusively, the in ovo feeding using CMH showed positive impacts on hatching weight and the development of gastrointestinal tract of chicks. However, caused negative impacts on hatchability.

Efficacy of creatine nitrate supplementation on redox status and mitochondrial function in pectoralis major muscle of preslaughter transported broilers.

This study was purposed to investigate the efficacy of dietary creatine nitrate (CrN) supplementation on redox status and mitochondrial function in pectoralis major (PM) muscle of broilers that experienced preslaughter transport. A total of 288 Arbor Acres broilers (28-day-old) were randomly assigned into five dietary treatments, including a basal diet or the basal diet supplemented with 600 mg/kg guanidinoacetic acid (GAA), 300, 600, or 900 mg/kg CrN for 14 days, respectively. On the transportation day, the basal diet group was divided into two groups on average, resulting in six groups. The control group was transported for 0.5 h and the other groups for 3 h (identified as Control, T3h, GAA600, CrN300, CrN600, and CrN900 group, respectively), and all crates were randomly placed on the truck travelling at an average speed of 80 km/h. Our results showed that GAA600 and CrN treatments decreased the muscle ROS level and MDA content (P < 0.05) and increased the mitochondrial membrane potential (P < 0.001), as well as a higher mRNA expression of avUCP (P < 0.001) and lower mRNA expressions of Nrf2 (P < 0.001), Nrf2 and PGC-1α (P < 0.05) compared with T3h group. Meanwhile, the mRNA and protein expressions of Nrf1, TFAM, and PGC-1α in CrN600 and CrN900 groups were lower than those in the T3h group (P < 0.05). Conclusively, dietary supplementation with GAA and CrN decreased muscle oxidative products and enhanced mitochondrial uncoupling mechanism and mtDNA copy number, which relieved muscle oxidative damage and maintained mitochondrial function.

The Effect of Skeletal Muscle-Specific Creatine Treatment on ALS NMJ Integrity and Function.

Although skeletal muscle (hSKM) has been proven to be actively involved in Amyotrophic Lateral Sclerosis (ALS) neuromuscular junction (NMJ) dysfunction, it is rarely considered as a pharmacological target in preclinical drug discovery. This project investigated how improving ALS hSKM viability and function effects NMJ integrity. Phenotypic ALS NMJ human-on-a-chip models developed from patient-derived induced pluripotent stem cells (iPSCs) were used to study the effect of hSKM-specific creatine treatment on clinically relevant functional ALS NMJ parameters, such as NMJ numbers, fidelity, stability, and fatigue index. Results indicated comparatively enhanced NMJ numbers, fidelity, and stability, as well as reduced fatigue index, across all hSKM-specific creatine-treated systems. Immunocytochemical analysis of the NMJs also revealed improved post-synaptic nicotinic Acetylcholine receptor (AChR) clustering and cluster size in systems supplemented with creatine relative to the un-dosed control. This work strongly suggests hSKM as a therapeutic target in ALS drug discovery. It also demonstrates the need to consider all tissues involved in multi-systemic diseases, such as ALS, in drug discovery efforts. Finally, this work further establishes the BioMEMs NMJ platform as an effective means of performing mutation-specific drug screening, which is a step towards personalized medicine for rare diseases.

Dietary creatine and guanidinoacetic acid supplementation have limited effects on hybrid striped bass.

The effects of dietary supplementation of creatine and guanidinoacetic acid (GDA) have been studied to a limited extent in various fish species including red drum (Sciaenops ocellatus) and hybrid striped bass (HBS) (Morone saxatilis x M. chrysops). However, in HSB, there is a need to better understand the impact of creatine and GDA supplementation at elevated salinity which may be encountered by this euryhaline fish. Therefore, two separate feeding trials were conducted at a salinity ranging from 15 to 20 g/L with juvenile HSB for 9 and 8 weeks to evaluate the effects of dietary creatine and GDA. In each trial, four diets were formulated with either singular additions of creatine at 2% of dry weight, GDA at 1% of dry weight, or a combination of both. Fish grew adequately in both feeding trials but no significant (P > 0.05) effects of supplemental creatine or GDA were observed on weight gain, feed efficiency, survival, hepatosomatic index (HSI), intraperitoneal fat (IPF ratio), or protein conversion efficiency (PCE). However, fish fed diets supplemented with creatine had significantly (P < 0.05) increased ash and reduced lipid deposition in whole-body tissues in the first feeding trial. Supplemental creatine also resulted in significantly higher muscle yield in the second trial, but no other effects on growth performance or body composition were observed. The addition of GDA to the diet had little effect except for significantly increasing the creatine content in the liver of fish in both feeding trials due to its role as a precursor and a catalyst for synthesis of creatine within the body. Based on the results of these two trials, supplemental creatine and GDA had rather limited effects on HSB cultured in moderately saline water.

Metabolites, gene expression, and gut microbiota profiles suggest the putative mechanisms via which dietary creatine increases the serum taurine and g-ABA contents in Megalobrama amblycephala.

A 90-day experiment was conducted to explore the effects of creatine on growth performance, liver health status, metabolites, and gut microbiota in Megalobrama amblycephala. There were 6 treatments as follows: control (CD, 29.41% carbohydrates), high carbohydrate (HCD, 38.14% carbohydrates), betaine (BET, 1.2% betaine + 39.76% carbohydrates), creatine 1 (CRE1, 0.5% creatine + 1.2% betaine + 39.29% carbohydrates), creatine 2 (CRE2, 1% creatine + 1.2% betaine + 39.50% carbohydrates), and creatine 3 (CRE3, 2% creatine + 1.2% betaine + 39.44% carbohydrates). The results showed that supplementing creatine and betaine together reduced the feed conversion ratio significantly (P < 0.05, compared to CD and HCD) and improved liver health (compared to HCD). Compared with the BET group, dietary creatine significantly increased the abundances of Firmicutes, Bacteroidota, ZOR0006, and Bacteroides and decreased the abundances of Proteobacteria, Fusobacteriota, Vibrio, Crenobacter, and Shewanella in the CRE1 group. Dietary creatine increased the content of taurine, arginine, ornithine, γ-aminobutyric acid (g-ABA), and creatine (CRE1 vs. BET group) and the expression of creatine kinase (ck), sulfinoalanine decarboxylase (csad), guanidinoacetate N-methyltransferase (gamt), glycine amidinotransferase (gatm), agmatinase (agmat), diamine oxidase1 (aoc1), and glutamate decarboxylase (gad) in the CRE1 group. Overall, these results suggested that dietary supplementation of creatine (0.5-2%) did not affect the growth performance, but it altered the gut microbial composition at the phylum and genus levels, which might be beneficial to the gut health of M. amblycephala; dietary creatine also increased the serum content of taurine by enhancing the expressions of ck and csad and increased the serum content of g-ABA by enhancing the arginine content and the expressions of gatm, agmat, gad, and aoc1.

Creatine supplementation reduces the cerebral oxidative and metabolic stress responses to acute in utero hypoxia in the late-gestation fetal sheep.

Prophylactic creatine treatment may reduce hypoxic brain injury due to its ability to sustain intracellular ATP levels thereby reducing oxidative and metabolic stress responses during oxygen deprivation. Using microdialysis, we investigated the real-time in vivo effects of fetal creatine supplementation on cerebral metabolism following acute in utero hypoxia caused by umbilical cord occlusion (UCO). Fetal sheep (118 days' gestational age (dGA)) were implanted with an inflatable Silastic cuff around the umbilical cord and a microdialysis probe inserted into the right cerebral hemisphere for interstitial fluid sampling. Creatine (6 mg kg-1  h-1 ) or saline was continuously infused intravenously from 122 dGA. At 131 dGA, a 10 min UCO was induced. Hourly microdialysis samples were obtained from -24 to 72 h post-UCO and analysed for percentage change of hydroxyl radicals (• OH) and interstitial metabolites (lactate, pyruvate, glutamate, glycerol, glycine). Histochemical markers of protein and lipid oxidation were assessed at post-mortem 72 h post-UCO. Prior to UCO, creatine treatment reduced pyruvate and glycerol concentrations in the microdialysate outflow. Creatine treatment reduced interstitial cerebral • OH outflow 0 to 24 h post-UCO. Fetuses with higher arterial creatine concentrations before UCO presented with reduced levels of hypoxaemia ( PO2${P_{{{\rm{O}}_{\rm{2}}}}}$ and SO2${S_{{{\rm{O}}_{\rm{2}}}}}$ ) during UCO which associated with reduced interstitial cerebral pyruvate, lactate and • OH accumulation. No effects of creatine treatment on immunohistochemical markers of oxidative stress were found. In conclusion, fetal creatine treatment decreased cerebral outflow of • OH and was associated with an improvement in cerebral bioenergetics following acute hypoxia. KEY POINTS: Fetal hypoxia can cause persistent metabolic and oxidative stress responses that disturb energy homeostasis in the brain. Creatine in its phosphorylated form is an endogenous phosphagen; therefore, supplementation is a proposed prophylactic treatment for fetal hypoxia. Fetal sheep instrumented with a cerebral microdialysis probe were continuously infused with or without creatine-monohydrate for 10 days before induction of 10 min umbilical cord occlusion (UCO; 131 days' gestation). Cerebral interstitial fluid was collected up to 72 h following UCO. Prior to UCO, fetal creatine supplementation reduced interstitial cerebral pyruvate and glycerol concentrations. Fetal creatine supplementation reduced cerebral hydroxyl radical efflux up to 24 h post-UCO. Fetuses with higher arterial creatine concentrations before UCO and reduced levels of systemic hypoxaemia during UCO were associated with reduced cerebral interstitial pyruvate, lactate and • OH following UCO. Creatine supplementation leads to some improvements in cerebral bioenergetics following in utero acute hypoxia.

Creatine deficiency and heart failure.

Impaired cardiac energy metabolism has been proposed as a mechanism common to different heart failure aetiologies. The energy-depletion hypothesis was pursued by several researchers, and is still a topic of considerable interest. Unlike most organs, in the heart, the creatine kinase system represents a major component of the metabolic machinery, as it functions as an energy shuttle between mitochondria and cytosol. In heart failure, the decrease in creatine level anticipates the reduction in adenosine triphosphate, and the degree of myocardial phosphocreatine/adenosine triphosphate ratio reduction correlates with disease severity, contractile dysfunction, and myocardial structural remodelling. However, it remains to be elucidated whether an impairment of phosphocreatine buffer activity contributes to the pathophysiology of heart failure and whether correcting this energy deficit might prove beneficial. The effects of creatine deficiency and the potential utility of creatine supplementation have been investigated in experimental and clinical models, showing controversial findings. The goal of this article is to provide a comprehensive overview on the role of creatine in cardiac energy metabolism, the assessment and clinical value of creatine deficiency in heart failure, and the possible options for the specific metabolic therapy.

Guanidinoacetic acid provides superior cardioprotection to its combined use with betaine and (or) creatine in HIIT-trained rats.

This study aimed to determine how guanidinoacetic acid (GAA) or its combined administration with betaine (B) or creatine (C) influences the cardiac function, morphometric parameters, and redox status of rats subjected to high-intensity interval training (HIIT). This research was conducted on male Wistar albino rats exposed to HIIT for 4 weeks. The animals were randomly divided into five groups: HIIT, HIIT + GAA, HIIT + GAA + C, HIIT + GAA + B, and HIIT + GAA + C + B. After completing the training protocol, GAA (300 mg/kg), C (280 mg/kg), and B (300 mg/kg) were applied daily per os for 4 weeks. GAA supplementation in combination with HIIT significantly decreased the level of both systemic and cardiac prooxidants ( O 2 - , H2O2, NO 2 - , and thiobarbituric acid reactive substances) compared with nontreated HIIT (p < 0.05). Also, GAA treatment led to an increase in glutathione and superoxide dismutase levels. None of the treatment regimens altered cardiac function. A larger degree of cardiomyocyte hypertrophy was observed in the HIIT + GAA group, which was reflected through an increase of the cross-sectional area of 27% (p < 0.05) and that of the left ventricle wall thickness of 27% (p < 0.05). Since we showed that GAA in combination with HIIT may ameliorate oxidative stress and does not alter cardiac function, the present study is a basis for future research exploring the mechanisms of cardioprotection induced by this supplement in an HIIT scenario.

Taurine supplementation improves hippocampal metabolism in immature rats with intrauterine growth restriction (IUGR) through protecting neurons and reducing gliosis.

Taurine as an essential amino acid in the brain could play an important role in protecting the fetal brain of intrauterine growth restriction (IUGR). The hippocampus with IUGR showed neural metabolic disorder and structure changed that affected memory and learning ability. This study was aimed to identify the effect of taurine supplementation on the metabolism alterations and cellular composition changes of the hippocampus in IUGR immature rats. Metabolite concentrations were determined by magnetic resonance spectroscopy (MRS) in the hippocampus of juvenile rats with IUGR following taurine supplementation with antenatal or postnatal supply. The composition of neural cells in the hippocampus was observed by immunohistochemical staining (IHC) and western blotting (WB). Antenatal taurine supplementation increased the ratios of N-acetylaspartate (NAA) /creatine (Cr) and glutamate (Glu) /Cr of the hippocampus in the IUGR immature rats, but reduced the ratios of choline (Cho) /Cr and myoinositol (mI) /Cr. At the same time, the protein expression of NeuN in the IUGR rats was increased through intrauterine taurine supplementation, and the GFAP expression was reduced. Especially the effect of antenatal taurine was better than postpartum. Furthermore, there existed a positive correlation between the NAA/Cr ratio and the NeuN protein expression (R = 0.496 p < 0.001 IHC; R = 0.568 p < 0.001 WB), the same results existed in the relationship between the mI/Cr ratio and the GFAP protein expression (R = 0.338 p = 0.019 IHC; R = 0.440 p = 0.002 WB). Prenatal taurine supplementation can better improve hippocampal neuronal metabolism by increasing NAA / Cr ratio related to the number of neurons and reducing Cho / Cr ratio related to the number of glial cells.

Interaction Between Caffeine and Creatine When Used as Concurrent Ergogenic Supplements: A Systematic Review.

There is some controversy regarding the interactions between creatine (CRE) and caffeine (CAF) supplements. The aim of this systematic review was to study whether such ergogenic interaction occurs and to analyze the protocol to optimize their synchronous use. The PubMed, Web of Science, MEDLINE, CINAHL, and SPORTDiscus databases were searched until November 2021 following the PRISMA guidelines. Ten studies were included. Three studies observed that CRE loading before an acute dose of CAF before exercise did not interfere in the beneficial effect of CAF, whereas one study reported that only an acute supplementation (SUP) of CAF was beneficial but not the acute SUP of both. When chronic SUP with CRE + CAF was used, two studies reported that CAF interfered in the beneficial effect of CRE, whereas three studies did not report interaction between concurrent SUP, and one study reported synergy. Possible mechanisms of interaction are opposite effects on relaxation time and gastrointestinal distress derived from concurrent SUP. CRE loading does not seem to interfere in the acute effect of CAF. However, chronic SUP of CAF during CRE loading could interfere in the beneficial effect of CRE.

Investigation of the nephroprotective effect of dexmedetomidine on colistin-induced nephrotoxicity in rats.

ACKGROUND: There are very few studies in the literature focusing on whether dexmedetomidine exerts a protective effect on colistin nephrotoxicity. Our study aims to investigate the nephroprotective effect of dexmedetomidine in an experimental model of nephrotoxicity in rats. METHODS: The control group was administered saline (SF) intraperitoneally twice a day. The colistin group received an intraperitoneal (ip) injection of 10 mg/kg of colistin twice a day. The DX10 group received 10 mg/kg of colistin 20 minutes after the intraperitoneal injection of 10 mcg/kg of dexmedetomidine. The DX20 group received 10 mg/kg of colistin 20 minutes after the intraperitoneal injection of 20 mcg/kg of dexmedetomidine. Applications were continued for 7 days, twice a day. All rats were sacrificed on the 8th day after blood and kidney tissue samples were taken. BUN, Creatine, KIM-1 and Endothelin-1 were studied in blood samples. RESULTS: There was a significant difference in the median values of Urea, BUN and Creatine between the groups (p<0.001, p<0.001, p<0.001, respectively). There was a significant difference in the median values of KIM-1 and Endothelin-1 between the groups (p=0.009, p=0.001, respectively). A significant difference was observed between the histopathological scores of the groups (p<0.001). CONCLUSION: Dexmedetomidine significantly decreased the elevated levels of BUN, Creatinine, KIM-1, and Endothelin-1 induced by colistin. Dexmedetomidine, at both doses, histopathologically prevented apoptosis and reduced the number of necrotic cells in the kidneys. Dexmedetomidine provides renoprotective effects, therefore it is a valuable sedation agent for clinicians working in intensive care units (Tab. 2, Fig. 4, Ref. 19). Text in PDF www.elis.sk Keywords: rat, colistin, nephrotoxicity, dexmedetomidine.

Altered calcium handling in cardiomyocytes from arginine-glycine amidinotransferase-knockout mice is rescued by creatine.

The creatine kinase system facilitates energy transfer between mitochondria and the major ATPases in the heart. Creatine-deficient mice, which lack arginine-glycine amidinotransferase (AGAT) to synthesize creatine and homoarginine, exhibit reduced cardiac contractility. We studied how the absence of a functional CK system influences calcium handling in isolated cardiomyocytes from AGAT-knockouts and wild-type littermates as well as in AGAT-knockout mice receiving lifelong creatine supplementation via the food. Using a combination of whole cell patch clamp and fluorescence microscopy, we demonstrate that the L-type calcium channel (LTCC) current amplitude and voltage range of activation were significantly lower in AGAT-knockout compared with wild-type littermates. Additionally, the inactivation of LTCC and the calcium transient decay were significantly slower. According to our modeling results, these changes can be reproduced by reducing three parameters in knockout mice when compared with wild-type: LTCC conductance, the exchange constant of Ca2+ transfer between subspace and cytosol, and SERCA activity. Because tissue expression of LTCC and SERCA protein were not significantly different between genotypes, this suggests the involvement of posttranslational regulatory mechanisms or structural reorganization. The AGAT-knockout phenotype of calcium handling was fully reversed by dietary creatine supplementation throughout life. Our results indicate reduced calcium cycling in cardiomyocytes from AGAT-knockouts and suggest that the creatine kinase system is important for the development of calcium handling in the heart.NEW & NOTEWORTHY Creatine-deficient mice lacking arginine-glycine amidinotransferase exhibit compromised cardiac function. Here, we show that this is at least partially due to an overall slowing of calcium dynamics. Calcium influx into the cytosol via the L-type calcium current (LTCC) is diminished, and the rate of the sarcoendoplasmic reticulum calcium ATPase (SERCA) pumping calcium back into the sarcoplasmic reticulum is slower. The expression of LTCC and SERCA did not change, suggesting that the changes are regulatory.