l-Arginine supplementation improves antioxidant defenses through l-arginine/nitric oxide pathways in exercised rats

Advances in the impact of ASS1 dysregulation on metabolic reprogramming of tumor cells

ASS1(argininosuccinate synthase 1) is a rate-limiting enzyme in the urea cycle, catalyzing the synthesis of argininosuccinate from citrulline and aspartate to ultimately produce arginine and support cellular metabolism. Increasing evidence suggests that ASS1 is commonly dysregulated in the tumor microenvironment, promoting tumor cell metastasis and infiltration. With a deeper understanding of tumor metabolic reprogramming in recent years, the impact of ASS1 dysregulation on abnormal tumor metabolism has attracted growing interest among researchers. In tumors with lacked or downregulated expression of ASS1, tumor cells become 'addicted' to exogenous arginine. Several strategies for arginine deprivation have been developed and entered clinical trials for treating such tumors. Therefore, we focus on elucidating the commonalities and characteristics of ASS1 dysregulation in tumors, as well as its implications for diagnosis, treatment, and prognosis. The mechanisms by which ASS1 gene dysregulation leads to metabolic abnormalities in tumor cells vary across different types of tumors. Extensive experimental studies have demonstrated that overexpression or low expression of ASS1 exhibits varying effects-either inhibitory or stimulatory proliferation-on tumor cells across different types. Restoring its expression can inhibit proliferation in some tumors lacking or downregulating ASS1 but can promote metastasis and infiltration in others (e.g., resistance to arginine deprivation therapy). Additionally, the expression level of ASS1 dynamically changes during tumorigenesis and progression. Finally, this review discusses the diagnostic, therapeutic, and prognostic value of ASS1 in future clinical practice.

L-Arginine and Nitric Oxide in Vascular Regulation-Experimental Findings in the Context of Blood Donation

This narrative review provides an analysis of the role of nitric oxide (NO) and its precursors, particularly L-arginine, in vascular regulation and health, with an emphasis on findings from our experimental research in animal models. NO serves as a critical mediator of vascular function, contributing to vasodilation, the regulation of blood flow, and the prevention of thrombosis. As a primary precursor of NO, L-arginine is essential for maintaining endothelial integrity, modulating mitochondrial function, and reducing oxidative damage. This review synthesises the data and contextualises these findings within the physiological challenges faced by blood donors, such as repeated blood donation and associated oxidative stress. It examines the effects of L-arginine supplementation on mitochondrial respiration, lipid peroxidation, and microsomal oxidation in different conditions, including differences in age, gender, and dietary interventions. The mechanisms by which L-arginine enhances NO production, improves vascular elasticity, and alleviates endothelial dysfunction caused by reduced NO bioavailability are also investigated. By integrating experimental findings with insights from the existing literature, this review provides a perspective on the potential of L-arginine supplementation to address the specific physiological needs of blood donors. It highlights the importance of personalised nutritional approaches in enhancing donor recovery and vascular resilience. In addition, this review assesses the wider implications of L-arginine supplementation in mitigating oxidative stress and preserving vascular function. The interplay between NO bioavailability, dietary factors, and physiological adaptation in blood donors is highlighted, along with the identification of current knowledge gaps and recommendations for future research. By presenting both original experimental evidence and a critical synthesis of the literature, this article highlights the therapeutic potential of NO precursors, particularly L-arginine, in promoting vascular health in the context of blood donation.

Dysregulated metabolic pathways associated with air pollution exposure and the risk of autism: Evidence from epidemiological studies

Autism spectrum disorder (ASD) is a developmental disorder with symptoms that range from social and communication impairments to restricted interests and repetitive behavior and is the 4th most disabling condition for children aged 5-14. Risk factors of ASD are not fully understood. Environmental risk factors are believed to play a significant role in the ASD epidemic. Research focusing on air pollution exposure as an early-life risk factor of autism is growing, with numerous studies finding associations of traffic and industrial emissions with an increased risk of ASD. One of the possible mechanisms linking autism and air pollution exposure is metabolic dysfunction. However, there were no consensus about the key metabolic pathways and corresponding metabolite signatures in mothers and children that are altered by air pollution exposure and cause the ASD. Therefore, we performed a review of published papers examining the metabolomic signatures and metabolic pathways that are associated with either air pollution exposure or ASD risk in human studies. In conclusion, we found that dysregulated lipid, fatty acid, amino acid, neurotransmitter, and microbiome metabolisms are associated with both short-term and long-term air pollution exposure and the risk of ASD. These dysregulated metabolisms may provide insights into ASD etiology related to air pollution exposure, particularly during the perinatal period in which neurodevelopment is highly susceptible to damage from oxidative stress and inflammation.

L-arginine attenuates dichlorvos-induced testicular toxicity in male Wistar rats by suppressing oxidative stress-dependent activation of caspase 3-mediated apoptosis

BACKGROUND

The continuous use of pesticides, such as dichlorvos, is a common agricultural and domestic practice. However, it is associated with shortfalls like testicular toxicity through the induction of oxidative stress-mediated signaling. On the other hand, L-arginine, a precursor of nitric oxide, has been reported to exert antioxidant activities and thus may attenuate dichlorvos-induced testicular toxicity.

AIM

Hence, this study was designed to evaluate the effect of L-arginine treatment on dichlorvos-induced testicular toxicity.

MATERIALS AND METHODS

Forty male Wistar rats were randomly assigned into four equal groups. The control rats were administered 0.5 mL of distilled water, dichlorvos- (DDVP-) treated rats were exposed to DDVP via inhalation for 15 min, DDVP + L-arginine-treated rats were exposed to DDVP and also received 100 mg/kg b.w/day, while L-arginine-treated rats received 100 mg/kg b.w/day.

RESULTS

DDVP exposure significantly reduced testicular nitric oxide, relative testicular weight, lowered sperm count, viability, and motility, and suppressed serum FSH, LH, and testosterone levels. These findings were associated with a rise in testicular malondialdehyde, TNF-α, IL-6, and 8OHdG levels and caspase 3 activities, and a reduction in GSH and superoxide dismutase. Additionally, on histopathological examination, DDVP was observed to reduce mature sperm cells in the seminiferous tubular lumen and induce focal vascular congestion in the interstitial space. Nonetheless, L-arginine treatment significantly attenuated DDVP-induced biochemical and histological alterations.

CONCLUSION

This study showed that L-arginine attenuated testicular toxicity by improving epididymal sperm variables and male sex hormones by suppressing oxidative stress, inflammation, and apoptosis in DDVP-exposed rats.

Multi-omics revealed anti-fatigue property of polyphenol from areca nut

BACKGROUND

Areca nut polyphenols (AP) that extracted from areca nut, have been demonstrated for their potential of anti-fatigue effects. However, the underlying mechanisms for the anti-fatigue properties of AP has not been fully elucidated to date. Previous studies have predominantly concentrated on single aspects, such as antioxidation and anti-inflammation, yet have lacked comprehensive multi-dimensional analyses.

PURPOSE

To explore the underlying mechanism of AP in exerting anti-fatigue effects.

METHODS

In this study, we developed a chronic sleep deprivation-induced fatigue model and used physiological, hematological, and biochemical indicators to evaluate the anti- fatigue efficacy of AP. Additionally, a multi-omics approach was employed to reveal the anti-fatigue mechanisms of AP from the perspective of microbiome, metabolome, and proteome.

RESULTS

The detection of physiology, hematology and biochemistry index indicated that AP markedly alleviate mice fatigue state induced by sleep deprivation. The 16S rRNA sequencing showed the AP promoted the abundance of probiotics (Odoribacter, Dubosiella, Marvinbryantia, and Eubacterium) and suppressed harmful bacteria (Ruminococcus). On the other hand, AP was found to regulate the expression of colonic proteins, such as increases of adenosine triphosphate (ATP) synthesis and mitochondrial function related proteins, including ATP5A1, ATP5O, ATP5L, ATP5H, NDUFA, NDUFB, NDUFS, and NDUFV. Serum metabolomic analysis revealed AP upregulated the levels of anti-fatigue amino acids, such as taurine, leucine, arginine, glutamine, lysine, and l-proline. Hepatic proteins express levels, especially tricarboxylic acid (TCA) cycle (CS, SDHB, MDH2, and DLST) and redox-related proteins (SOD1, SOD2, GPX4, and PRDX3), were significantly recovered by AP administration. Spearman correlation analysis uncovered the strong correlation between microbiome, metabolome and proteome, suggesting the anti-fatigue effects of AP is attribute to the energy homeostasis and redox balance through gut-liver axis.

CONCLUSION

AP increased colonic ATP production and improve mitochondrial function by regulating gut microbiota, and further upregulated anti-fatigue amino acid levels in the blood. Based on the gut-liver axis, AP upregulated the hepatic tricarboxylic acid cycle and oxidoreductase-related protein expression, regulating energy homeostasis and redox balance, and ultimately exerting anti-fatigue effects. This study provides insights into the anti-fatigue mechanisms of AP, highlighting its potential as a therapeutic agent.

Oyster (Ostrea Plicatula Gmelin) Peptides Improve Exercise Endurance Capacity via Activating AMPK and HO-1

OBJECTIVE

Previous studies have shown that oyster peptides (OPs) have antioxidant and anti-fatigue activities. This study aimed to investigate the effects of OPs on swimming endurance in mice and the underlying mechanisms.

METHODS

The mice were subjected to gavage with OPs and subjected to exercise training. After 14 days, various biochemical indicators in the blood and gastrocnemius muscle of mice were assessed, and real-time PCR was utilized to detect the level of signal pathway regulation by OPs in the gastrocnemius muscle. Molecular docking technology was employed to observe the potential active components in OPs that regulate signal pathways.

RESULTS

In this study, OPs supplementation combined with and without exercise significantly extended swimming time compared to the sedentary group. OPs supplementation with exercise also increased glycogen levels and decreased blood urea nitrogen, lactate dehydrogenase, and lactic acid levels. Additionally, mice in the exercise with OPs group exhibited higher activities of antioxidant enzymes. OPs can upregulate metabolic regulatory factors such as AMP-activated protein kinase, peroxisome proliferator-activated receptor gamma coactivator-1 alpha, peroxisome proliferator-activated receptor delta, and glucose transporter 4, thereby increasing energy supply during exercise. Additionally, OPs enhances the expression of heme oxygenase 1 and superoxide dismutase 2, thereby reducing oxidative stress during physical activity. Molecular docking analyses revealed that peptides found in OPs formed hydrogen bonds with AMPK and HO-1, indicating that they can exert bioactivity by activating target proteins such as AMPK and HO-1.

CONCLUSIONS

OPs supplementation improved energy reserves, modulated energy metabolism pathways, and coordinated antioxidative stress responses, ultimately enhancing swimming endurance. These findings suggest that OPs have the potential to improve exercise levels by promoting metabolism and improving energy utilization efficiency.

The effects of omega-3 fatty acids on antioxidant enzyme activities and nitric oxide levels in the cerebral cortex of rats treated ethanol

The toxic effect of ethanol on the cerebral cortex and protective effects of omega-3 fatty acids against this neurotoxicity were investigated. Twenty eight male Wistar-albino rats were divided into 4 groups. Rats of the ethanol and ethanol withdrawal groups were treated with ethanol (6 g/kg/day) for 15 days. Animals of the ethanol+omega-3 group received omega-3 fatty acids (400 mg/kg daily) and ethanol. In rats of the ethanol group SOD activity was lower than in animals of the control group. In rats treated with omega-3 fatty acids along with ethanol SOD, activity increased. GSH-Px activity and MDA levels in animals of all groups were similar. In ethanol treated rats NO levels significantly decreased as compared to the animals of the control group (6.45±0.24 nmol/g vs 11.05±0.53 nmol/g, p.

Early microbial intervention reshapes phenotypes of newborn Bos taurus through metabolic regulations

BACKGROUND

The rumen of neonatal calves has limited functionality, and establishing intestinal microbiota may play a crucial role in their health and performance. Thus, we aim to explore the temporal colonization of the gut microbiome and the benefits of early microbial transplantation (MT) in newborn calves.

RESULTS

We followed 36 newborn calves for 2 months and found that the composition and ecological interactions of their gut microbiomes likely reached maturity 1 month after birth. Temporal changes in the gut microbiome of newborn calves are widely associated with changes in their physiological statuses, such as growth and fiber digestion. Importantly, we observed that MT reshapes the gut microbiome of newborns by altering the abundance and interaction of Bacteroides species, as well as amino acid pathways, such as arginine biosynthesis. Two-year follow-up of those calves further showed that MT improves their later milk production. Notably, MT improves fiber digestion and antioxidant capacity of newborns while reducing diarrhea. MT also contributes to significant changes in the metabolomic landscape, and with putative causal mediation analysis, we suggest that altered gut microbial composition in newborns may influence physiological status through microbial-derived metabolites.

CONCLUSIONS

Our study provides a metagenomic and metabolomic atlas of the temporal development of the gut microbiome in newborn calves. MT can alter the gut microbiome of newborns, leading to improved physiological status and later milk production. The data may help develop strategies to manipulate the gut microbiota during early life, which may be relevant to the health and production of newborn calves.

Differential benefits of physical training associated or not with L-arginine supplementation in rats with metabolic syndrome: evaluation of cardiovascular, autonomic and metabolic parameters

Metabolic syndrome (MetS) is characterized by endocrine-metabolic and cardiac alterations that increase the risk of cardiovascular disease, dyslipidemia, and type-2 diabetes mellitus. Dietary supplementation with L-Arginine (L-Arg) is beneficial for fat loss, while chronic aerobic exercise has several benefits in reversing cardiovascular, autonomic, and metabolic dysfunctions caused by obesity. However, the association between these two approaches has not yet been described. This study aimed to evaluate the possible benefits of physical training, with or without L-Arg supplementation, on cardiovascular, autonomic, and metabolic parameters in rats with MetS, which was induced by the subcutaneous administration of monosodium glutamate at 4 mg g^-1day^-1 in rats from the first to fifth day of life. Physical training on a treadmill and supplementation with L-Arg in adulthood were carried out concomitantly for 8 weeks. After this, the animals underwent femoral artery catheterization to record their cardiovascular parameters and autonomic modulation. Organs and blood were removed to measure levels of nitrite, glucose, and hepatic steatosis. In adult rats with MetS, supplementation with L-Arg in combination with physical training reduced hypertension, tachycardia, adipose tissue mass, free fatty acids, and hepatic steatosis. Supplementation with L-Arg and physical training separately was beneficial in reducing several aspects of MetS, but a combination of both was especially effective in reducing adipose tissue and hepatic steatosis. Together, the two therapies can form a good strategy to combat MetS.

Effects of supplementation with different concentrations of L-citrulline on the plasma amino acid concentration, reproductive hormone concentrations, antioxidant capacity, and reproductive performance of Hu ewes

Context L-citrulline (L-Cit) does not degrade in the rumen and has the ability to form peptide bonds in the body; however, it does not participate in protein synthesis. Aims This study aimed to evaluate the effects of L-Cit on the reproductive performance of Hu ewes. Methods In total, 30 ewes were randomly categorised into five groups. The control group was fed with a basic diet, whereas the Experimental Groups I, II, III, and IV were provided feed supplemented with 5, 10, 15, and 20 g/day of L-Cit respectively. Blood samples of ewes were collected 4 h after feeding on Day 21 of the experiment and before feeding on Day 30. The optimal supplementary feeding dose was selected on the basis of blood biochemical indexes. Overall, ninety 2-year-old ewes were classified into two groups. The control group was fed with a basic diet and the experimental group was fed with a diet supplemented with 10 g/day of L-Cit. After 30 days of supplementary feeding, reproductive performance of ewes was determined. Key results The plasma concentrations of Cit, ornithine, and arginine in ewes increased linearly with an increase in the level of L-Cit supplementation. The plasma concentrations of gonadotropin-releasing hormone, luteinising hormone, and follicle-stimulating hormone in the experimental group increased significantly compared with those in the control group. The plasma total antioxidant capacity and catalase, superoxide dismutase, and glutathione peroxidase in the experimental group were significantly higher than those in the control group, whereas the concentrations of malondialdehyde in all experimental groups were significantly lower than those in the control group. The conception, lambing, and double lambing rates of the experimental group were increased by 28.76%, 15.90%, and 40.21% respectively. Conclusions Supplementation with different doses of L-Cit can improve the concentrations of some plasma amino acids and reproductive hormones as well as antioxidant capacity of ewes. Supplementary feeding with 10 g/day of L-Cit could increase the lambing and double lambing rates of ewes. Implication L-Cit can improve the reproductive performance of ewes.

Effects of l-arginine supplementation in patients with sickle cell disease: A systematic review and meta-analysis of clinical trials

Background and Aims

Previous studies have shown that supplementation of some amino acids such as l-arginine or its precursors could exert beneficial effects in patients with sickle cell disease (SCD). The objective of this study is to systematically review the literature to assess the effect of arginine administration on the clinical and paraclinical parameters of patients with SCD.

Methods

Four online databases of PubMed, Web of Sciences, Scopus, and Embase were selected for systematic search. Eligible studies were clinical trials that evaluated the effect of arginine usage in patients with SCD. Effects sizes were calculated using weighted mean difference (WMD) and Hedge's g and they were pooled using random-effects modeling with Hartung-Knapp adjustment. Additional analyses were also conducted.

Results

Twelve studies containing detail of 399 patients with SCD were found to be eligible. The data synthesis showed that l-arginine significantly increased the level of NO metabolites (Hedge's g: 1.50, 0.48-1.82, I 2: 88%) and hemoglobin F (WMD: 1.69%, 0.86-2.52, I 2: 0%) and significantly decreased systolic blood pressure (WMD: -8.46 mmHg, -15.58 to -1.33, I 2: 53%) and aspartate transaminase (Hedge's g: -0.49, -0.73 to -0.26, I 2: 0%). However, there were no significant effects on hemoglobin, reticulocyte, malondialdehyde and diastolic blood pressure, and alanine transaminase.

Conclusion

Our meta-analysis showed that l-arginine use for SCD could be beneficial, increase hemoglobin F and exert blood pressure-lowering and hepatoprotective properties. However, for a firm conclusion and widespread use of  l-arginine for these patients, more studies are needed.

Swimming exercise and nano-l-arginine supplementation improve oxidative capacity and some autophagy-related genes in the soleus muscle of aging rats

The present research aims to evaluate the effect of swimming exercise and chitosan-coated l-arginine on mitochondrial oxidation, BCL2 Interacting Protein 3 (Bnip3), NIP-like protein × (Nix), B-cell lymphoma-extra-large (Bcl-xL) and autophagy-related protein light chain 3(LC3) expression in soleus muscle of aging rats. In this experimental research, 25 male Wistar rats were assigned into five groups randomly: young, old, old + Nano l-arginine (Nano L-a), old + exercise (Ex), and old + Nano l-arginine (Nano L-a) + exercise (Ex) (n = 5 in each). They performed a swimming exercise program five days a week for six weeks. To determine the relative strength for rats before and after performing these interventions, the 1repetition maximum (1RM) test was done as a pre and post-test. The exercise program started with 20 min and after four sessions, gradually increased to 60 min and this time was maintained until the completion of the training period. l-arginine coated with chitosan nanoparticles was given to the rats in the l-arginine-supplemented group via gavage at a dosage of 500 mg/kg/day, five days a week, for six weeks. Additionally, the rats in all groups were fed a normal diet (2.87 kcal/g and 15 % energy from fat). Upon the completion of the protocol implementation, the rats were sacrificed and the soleus muscle was fixed and frozen to determine hematoxylin and eosin (H&E) staining, immunohistochemistry (IHC), gene expression analysis, levels of reactive oxygen species (ROS), and total antioxidant capacity (TAC). The results from the present research indicated that swimming exercise and Nano l-arginine improve the strength and histology of muscle tissue in old rats (p < 0.05). Aging significantly increased the expression of Nix and Bnip3 (p < 0.05) and reduced the Bcl-xL gene expression (p < 0.05). The expression of LC3 protein also increased with aging (p < 0.05). Therapeutic interventions, such as combined treatment (old + Nano L-a + Ex) for old animals, reduced the amount of this protein in soleus muscle (p < 0.05). The ROS values also showed a significant reduction only in the old + Nano L-a + Ex group compared to the old group. Moreover, TAC values show a significant decrease in the old and old + Ex groups in comparison to the young group. The use of arginine supplement, especially in nano form, along with swimming exercise seems to reduce the oxidative damage to the elderly muscle tissue, which has a positive effect on the structure and function of the soleus muscle. Since these interventions only had a significant effect on LC3 protein, further studies with more diverse measurement methods for autophagy are suggested.

Effects of Antioxidants in Human Milk on Bronchopulmonary Dysplasia Prevention and Treatment: A Review

Bronchopulmonary dysplasia (BPD) is a severe chronic lung illness that affects neonates, particularly premature infants. It has far-reaching consequences for infant health and their families due to intractable short- and long-term repercussions. Premature infant survival and long-term quality of life are severely harmed by BPD, which is characterized by alveolarization arrest and hypoplasia of pulmonary microvascular cells. BPD can be caused by various factors, with oxidative stress (OS) being the most common. Premature infants frequently require breathing support, which results in a hyperoxic environment in the developing lung and obstructs lung growth. OS can damage the lungs of infants by inducing cell death, inhibiting alveolarization, inducing inflammation, and impairing pulmonary angiogenesis. Therefore, antioxidant therapy for BPD relieves OS and lung injury in preterm newborns. Many antioxidants have been found in human milk, including superoxide dismutase, glutathione peroxidase, glutathione, vitamins, melatonin, short-chain fatty acids, and phytochemicals. Human milk oligosaccharides, milk fat globule membrane, and lactoferrin, all unique to human milk, also have antioxidant properties. Hence, human milk may help prevent OS injury and improve BPD prognosis in premature infants. In this review, we explored the role of OS in the pathophysiology of BPD and related signaling pathways. Furthermore, we examined antioxidants in human milk and how they could play a role in BPD to understand whether human milk could prevent and treat BPD.

Integrated Metabolomics and Transcriptomics Analyses Reveal Metabolic Mechanisms in Porcine Intestinal Epithelial Cells under Zearalenone Stress

Zearalenone (ZEA) is a mycotoxin that frequently occurs in agricultural crops and related products and seriously threatens both animal feed and human food safety. To identify key metabolites and regulators involved in ZEA toxicological processes, we performed metabolomic and transcriptomic analyses of porcine IPEC-J2 intestinal epithelial cells upon ZEA exposure using liquid chromatography-mass spectrometry (LC-MS)/MS and RNA-seq techniques. A total of 325 differential metabolites and 5646 differentially expressed genes were detected. Integrated analyses of metabolomic and transcriptomic data indicated that metabolic processes including lipid metabolism, amino acid metabolism, and carbohydrate metabolism were most affected. Exogenous addition of the key metabolite l-arginine significantly facilitated ZEA metabolism and ameliorated ZEA-induced reactive oxygen species levels and cell apoptosis. Furthermore, l -arginine contributed to the expression of phase II detoxification genes (SULT2B1, GSTA1, GSTM3, and GPX4). l-Arginine addition also increased the protein levels of LC3-II and Beclin 1, and downregulated p62/SQSTM1 levels, indicating its regulatory roles in autophagic flux activation upon ZEA exposure. This study provided global insights into metabolic and transcriptional changes as well as key metabolites and regulators underlying the cellular response to ZEA exposure, and paved the way for the identification of metabolic and molecular targets for biomonitoring and controlling contamination by ZEA.

Association between Protein Intake and the Risk of Hypertension among Chinese Men and Women: A Longitudinal Study

This study aimed to examine the relationship between hypertension risk and protein intake in Chinese individuals. Our analysis included 7007 men and 7752 women from 9 China Health and Nutrition Survey waves (1991−2015). The main outcome was incident hypertension. Dietary intake was recorded using a combination of 3 consecutive 24-h recalls and a household food inventory survey. Energy-adjusted cumulative average intakes were analyzed, and Cox proportional hazards regression models were built. After 143,035 person-years of follow-up, 2586 and 2376 new male and female hypertension cases were identified, respectively. In multivariate-adjusted models with dietary protein intakes included as categorical variables, higher animal protein intake was associated with lower hypertension risk in women (p-trend = 0.01), whereas non-significant in men. Plant protein intake showed a significant positive correlation with hypertension risk, while non-significant for total protein. On a continuous scale, restricted cubic spline curves visually revealed L-, J-, and U-shaped associations between hypertension risk and animal-, plant-, and total-protein intakes, respectively, in both sexes (all p-nonlinearity < 0.0001). Our results suggest a beneficial association between intakes of animal, plant, and total proteins and hypertension risk at lower intake levels, and excessive intake of plant or total protein may increase the hypertension risk in the Chinese population.

Evaluation of Pediococcus pentosaceus strains as probiotic adjunct cultures for soybean milk post-fermentation

Soybean milk is an economical substitute for dairy products. Pediococcus pentosaceus has been used as a food additive to improve taste, nutrition, and food safety. In this study, four P. pentosaceus strains (CICC 24444, QK-1, MQ-1 and RQ-1) isolated from various food sources and known to exhibit broad-spectrum antibacterial activities were used to ferment soybean milk, and their fermentation characteristics and the properties of the resulting beverages were evaluated. The results revealed that the P. pentosaceus strains can inhibited the growth of five types of pathogenic bacteria (Salmonella enterica subsp. enterica serotype Enteritidis, Yersinia enterocolitica, Shigella dysenteriae, Escherichia coli, and Staphylococcus aureus), and their in vitro survival rates in the simulated stomach and intestinal environments were above 90%, satisfying the probiotic requirements. Isomaltose oligosaccharide was used as a protective agent to resist low-temperature freeze-drying damage and ensure a high survival rate, and P. pentosaceus was directly injected into fermented soymilk. The acidification of fermented soybean milk was the weakest with P. pentosaceus QK-1, and the viable bacterial counts of all strains were stable after 28 days of storage. After fermentation, the antioxidant ability was enhanced. Arginine and β-alanine levels increased after fermentation, and the adjunct culture of P. pentosaceus QK-1 increased proline levels. Our data indicate that P. pentosaceus QK-1 is a suitable strain for the development of functional plant-based beverages.

Influence of arginine on the biocontrol efficiency of Metschnikowia citriensis against Geotrichum citri-aurantii causing sour rot of postharvest citrus fruit

This study investigated the effect of arginine (Arg) on the antagonistic activity of Metschnikowia citriensis against sour rot caused by Geotrichum citri-aurantii in postharvest citrus, and evaluated the possible mechanism therein. Arg treatment up-regulated the PUL genes expression, and significantly induced the pulcherriminic acid (PA) production of M. citriensis, which related to the capability of iron depletion of M. citriensis. By comparing the biocontrol effects of Arg-treated and untreated yeast cells, it was found that Arg treatment significantly enhanced the biocontrol efficacy of M. citriensis, and 5 mmol L^-1 Arg exerted the best effect. Additionally, the biofilm formation ability of M. citriensis was greatly enhanced by Arg, and the higher population density of yeast cells in citrus wounds was also observed in Arg treatment groups stored both at 25 °C and 4 °C. Moreover, Arg was shown to function as a cell protectant to elevate antioxidant enzyme activity [including catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPX)] and intracellular trehalose content to resist oxidative stress damage, that directly helped to enhance colonization ability of yeasts in fruit wounds. These results suggest the application of Arg is a useful approach to improve the biocontrol performance of M. citriensis.

Antiseptic mouthwash inhibits antihypertensive and vascular protective effects of L-arginine

L-arginine supplementation increases nitric oxide (NO) formation and bioavailability in hypertension. We tested the possibility that many effects of L-arginine are mediated by increased formation of NO and enhanced nitrite, nitrate and nitrosylated species concentrations, thus stimulating the enterosalivary cycle of nitrate. Those effects could be prevented by antiseptic mouthwash. We examined how the derangement of the enterosalivary cycle of nitrate affects the improvement of endothelial dysfunction (assessed with isolated aortic ring preparation), the antihypertensive (assessed by tail-cuff blood pressure measurement) and the antioxidant effects (assessed with the fluorescent dye DHE) of L-arginine in two-kidney, one-clip hypertension model in rats by using chlorhexidine to decrease the number of oral bacteria and to decrease nitrate reductase activity assessed from the tongue (by ozone-based chemiluminiscence assay). Nitrite, nitrate and nitrosylated species concentrations were assessed (ozone-based chemiluminiscence). Chlorhexidine mouthwash reduced the number of oral bacteria and tended to decrease the nitrate reductase activity from the tongue. Antiseptic mouthwash blunted the improvement of the endothelial dysfunction and the antihypertensive effects of L-arginine, impaired L-arginine-induced increases in plasma nitrite and nitrosylated species concentrations, and blunted L-arginine-induced increases in aortic nitrate concentrations and vascular antioxidant effects. Our results show for the first time that the vascular and antihypertensive effects of L-arginine are prevented by antiseptic mouthwash. These findings show an important new mechanism that should be taken into consideration to explain how the use of antibacterial mouth rinse may affect arterial blood pressure and the risk of developing cardiovascular and other diseases.

Immunonutrition effects on coping with COVID-19

COVID-19 implications are still a threat to global health. In the face of this pandemic, food and nutrition are key issues that can boost the immune system. The bioactivity of functional foods and nutrients (probiotics, prebiotics, water- and fat-soluble vitamins, minerals, flavonoids, glutamine, arginine, nucleotides, and PUFAs) contributes to immune system modulation, which establishes the status of nutrients as a factor of immune competence. These foods can contribute, especially during a pandemic, to the minimization of complications of SARS-CoV-2 infection. Therefore, it is important to support the nutritional strategies for strengthening the immune status, associated with good eating habits, as a way to confront COVID-19.

L-Arginine alleviates the testosterone reduction in heat-treated mice by upregulating LH secretion, the testicular antioxidant system and expression of steroidogenesis-related genes

High temperature can reduce testes function, leading to decreased testosterone secretion. Dietary l-arginine (l-Arg) supplementation improves the semen quality and libido of boars. The present study investigated whether l-Arg could enhance the production of testosterone in mice exposed to high ambient temperature. Twenty-four 6-week-old male ICR mice were randomly divided into three groups: a control group, a heat-treated (HT) group and a group subjected to heat treatment plus 2mg kg-1 l-Arg (HT+Arg). l-Arg was administered to mice by oral gavage for 18 consecutive days, after which the HT and HT+Arg groups were placed into an incubator at 40°C for 30min every day for 5 days. Serum testosterone and LH concentrations were significantly increased in the HT+Arg compared with HT group, as was catalase, total superoxide dismutase and glutathione peroxidase activity and the expression of steroidogenesis-related genes steroidogenic acute regulatory protein (Star), steroidogenic factor-1 (Sf1), 17β-hydroxysteroid dehydrogenase 3 (Hsd17b3) and 17α-hydroxylase/17,20-lyase (Cyp17a1) in the testes. These results demonstrate that l-Arg can alleviate testosterone reductions in heat-treated mice by upregulating LH secretion, enhancing the antioxidant system and increasing the expression of testosterone synthesis-related genes.

L-Arginine Improves Endurance to High-Intensity Interval Exercises in Overweight Men

The effects of acute consumption of L-Arginine (L-Arg) in healthy young individuals are not clearly defined, and no studies on the effects of L-Arg in individuals with abnormal body mass index undertaking strenuous exercise exist. Thus, we examined whether supplementation with L-Arg diminishes cardiopulmonary exercise testing responses, such as ventilation (VE), VE/VCO2, oxygen uptake (VO2), and heart rate, in response to an acute session of high-intensity interval exercise (HIIE) in overweight men. A double-blind, randomized crossover design was used to study 30 overweight men (age, 26.5 ± 2.2 years; body weight, 88.2 ± 5.3 kilogram; body mass index, 28.0 ± 1.4 kg/m2). Participants first completed a ramped-treadmill exercise protocol to determine VO2max velocity (vVO2max), after which they participated in two sessions of HIIE. Participants were randomly assigned to receive either 6 g of L-Arg or placebo supplements. The HIIE treadmill running protocol consisted of 12 trials, including exercise at 100% of vVO2max for 1 min interspersed with recovery intervals of 40% of vVO2max for 2 min. Measurements of VO2 (ml·kg-1·min-1), VE (L/min), heart rate (beat per min), and VE/VCO2 were obtained. Supplementation with L-Arg significantly decreased all cardiorespiratory responses during HIIE (placebo+HIIE vs. L-Arg+HIIE for each measurement: VE [80.9 ± 4.3 L/min vs. 74.6 ± 3.5 L/min, p < .05, ES = 1.61], VE/VCO2 [26.4 ± 1.3 vs. 24.4 ± 1.0, p < .05, ES = 1.8], VO2 [26.4 ± 0.8 ml·kg-1·min-1 vs. 24.4 ± 0.9 ml·kg-1·min-1, p < .05, ES = 2.2], and heart rate [159.7 ± 6.3 beats/min vs. 155.0 ± 3.7 beats/min, p < .05, d = 0.89]). The authors conclude consuming L-Arg before HIIE can alleviate the excessive physiological strain resulting from HIIE and help to increase exercise tolerance in participants with a higher body mass index who may need to exercise on a regular basis for extended periods to improve their health.

Arginine and Endothelial Function

Arginine (L-arginine), is an amino acid involved in a number of biological processes, including the biosynthesis of proteins, host immune response, urea cycle, and nitric oxide production. In this systematic review, we focus on the functional role of arginine in the regulation of endothelial function and vascular tone. Both clinical and preclinical studies are examined, analyzing the effects of arginine supplementation in hypertension, ischemic heart disease, aging, peripheral artery disease, and diabetes mellitus.

Amelioration of Cisplatin-Induced Ototoxicity in Rats by L-arginine: The Role of Nitric Oxide, Transforming Growth Factor Beta 1 and Nrf2/HO-1 Pathway

BACKGROUND

Cisplatin is an alkylating agent that inhibits DNA replication and interferes with proliferation of cancer cells. However, the major limiting factor for its use is the possible development of adverse effects, including ototoxicity. Up till now, the mechanisms of this ototoxicity remain poorly understood. However, induction of oxidative stress and activation of the inflammatory cascade were suggested as contributing factors.

PURPOSE

The aim of this study was to explore the effect of L-arginine on cisplatin-induced ototoxicity in rats.

METHODS

Thirty male adult Wistar rats were divided into three equal groups as follows: control group; cisplatin group and cisplatin + L-arginine group. Auditory brainstem response (ABR), tissue oxidative stress parameters, total nitrate/nitrite, nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/heme oxygenase-1 (HO-1) content, transforming growth factor beta 1 (TGF-β1), tumor necrosis factor alpha (TNF-α) and interleukin 15 (IL-15) were assessed. Also, the cochlear tissues were subjected to histopathological and electron microscopic examination.

RESULTS

Administration of L-arginine to cisplatin-treated rats induced significant decrease in the average ABR threshold shifts at all frequencies, tissue TGF-β1, TNF-α and IL-15 associated with significant increase in tissue antioxidant enzymes, total nitrate/nitrite and Nrf2/HO-1 content compared to cisplatin group. Also, pretreatment of cisplatin-injected rats with L-arginine induced significant improvement of the histopathological and electron microscopic picture compared to cisplatin group.

CONCLUSION

L-arginine may serve as a promising therapeutic modality for amelioration of cisplatin-induced ototoxicity.
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Insulinotropic and antidiabetic effects of β-caryophyllene with l-arginine in type 2 diabetic rats

Beta-caryophyllene (BCP) is a flavoring agent, whereas l-arginine (LA) is used as a food supplement. They possess insulinotropic and β cell regeneration activities, respectively. We assessed the antidiabetic potential of BCP, LA, and its combination in RIN-5F cell lines and diabetic rats. Ex vivo studies were carried out for glucose uptake and absorption of the combination of BCP with LA. The results indicated that the combination of BCP with LA showed a significant decrease in glucose absorption and an increase in its uptake in tissues and also an increase in insulin secretion in RIN-5F cells. The combination treatment of BCP with LA showed a significant reduction in glucose, lipid levels, and oxidative stress in pancreatic tissue when compared with the diabetic group. Furthermore, the combination of BCP with LA normalized glucose tolerance and pancreatic cell damage in diabetic rats. In conclusion, the combinational treatment showed significant potentials in the treatment of type 2 diabetes mellitus. PRACTICAL APPLICATIONS: Type 2 diabetes mellitus is the most prevalent chronic metabolic disorder affecting a large population. Beta-caryophyllene is a CB₂ receptor agonist shown to have insulinotropic activity. l-Arginine is a food supplement that possesses beta-cell regeneration property. The combination of BCP with LA could work as a potential therapeutic intervention, considering the individual pharmacological activities of each. We evaluated the antidiabetic activity of the combination of BCP with LA in diabetic rats using ex vivo and in vitro experimentations. Results from the study revealed that the combination of BCP with LA showed a significant (p < .001) reduction in glucose and lipid levels as compared to individual treatment. In vitro study also supports the diabetic potential of the combination of BCP with LA in the glucose-induced insulin secretion in RIN-5F cell lines. The study indicates a therapeutic approach to treat T2DM by BCP and LA combination as food and dietary supplement.

Oxidative Stress: Role and Response of Short Guanine Tracts at Genomic Locations

Over the decades, oxidative stress has emerged as a major concern to biological researchers. It is involved in the pathogenesis of various lifestyle-related diseases such as hypertension, diabetes, atherosclerosis, and neurodegenerative diseases. The connection between oxidative stress and telomere shortening via oxidative guanine lesion is well documented. Telomeres are confined to guanine rich ends of chromosomes. Owing to its self-association properties, it adopts G-quadruplex structures and hampers the overexpression of telomerase in the cancer cells. Guanine, being the most oxidation prone nucleobase, when structured in G-quadruplex entity, is found to respond peculiarly towards oxidative stress. Interestingly, this non-Watson-Crick structural feature exists abundantly in promoters of various oncogenes, exons and other genomic locations. The involvement of G-quadruplex architecture in oncogene promoters is well recognized in gene regulation processes. Development of small molecules aimed to target G-quadruplex structures, have found to alter the overexpression of oncogenes. The interaction may lead to the obstruction of diseased cell having elevated level of reactive oxygen species (ROS). Thus, presence of short guanine tracts (Gn) forming G-quadruplexes suggests its critical role in oxidative genome damage. Present review is a modest attempt to gain insight on the association of oxidative stress and G-quadruplexes, in various biological processes.

Effect of amino-acid intake on physical conditions and skin state: a randomized, double-blind, placebo-controlled, crossover trial

The objective of this study is to elucidate the effect of a supplement enriched with l-leucine, l-arginine, and l-glutamine on body compositions/skin conditions. Healthy young women (n = 29) were allocated to a group (n = 14) receiving an amino-acid supplement (600 mg l-leucine, 250 mg l-arginine, and 300 mg l-glutamine) and a placebo group (n = 15) receiving a supplement not-containing the amino acids. The amino-acid supplement and placebo were given twice/day for 6 weeks. After a wash-out (2 months) from the 1st test, the amino-acid group received the placebo and the placebo group the amino-acid supplement. The body compositions/skin conditions were measured 4 times (day 1 and weeks 2, 4, and 6) in each test. Percentage-change of muscle mass in the amino-acid group increased up to 4 weeks (p = 0.05) and was higher than that in the placebo group (p = 0.09). Skin texture estimated by the image processing of neck skin replica tended to increase in the amino-acid group at 6 weeks compared with that at 0 week, though there was no significant intergroup difference. In conclusion, the young adult women having no fitness habit showed the significant increase of the muscle amount and improvement tendency of the skin texture by the continuous intake of the amino-acid supplement.

Decreased plasma l-arginine levels in organic acidurias (MMA and PA) and decreased plasma branched-chain amino acid levels in urea cycle disorders as a potential cause of growth retardation: Options for treatment

BACKGROUND AND AIM

Patients with methylmalonic acidemia (MMA) and propionic acidemia (PA) and urea cycle disorders (UCD), treated with a protein restricted diet, are prone to growth failure. To obtain optimal growth and thereby efficacious protein incorporation, a diet containing the essential and functional amino acids for growth is necessary. Optimal growth will result in improved protein tolerance and possibly a decrease in the number of decompensations. It thus needs to be determined if amino acid deficiencies are associated with the growth retardation in these patient groups. We studied the correlations between plasma L-arginine levels, plasma branched chain amino acids (BCAA: L-isoleucine, L-leucine and L-valine) levels (amino acids known to influence growth), and height in MMA/PA and UCD patients.

METHODS

We analyzed data from longitudinal visits made in stable metabolic periods by patients registered at the European Registry and Network for Intoxication Type Metabolic Diseases (E-IMD, Chafea no. 2010 12 01).

RESULTS

In total, 263 MMA/PA and 311 UCD patients were included, all aged below 18 years of age. In patients with MMA and PA, height z-score was positively associated with patients' natural-protein-to-energy prescription ratio and their plasma L-valine and L-arginine levels, while negatively associated with the amount of synthetic protein prescription and their age at visit. In all UCDs combined, height z-score was positively associated with the natural-protein-to-energy prescription ratio. In those with carbamylphosphate synthetase 1 deficiency (CPS1-D), those with male ornithine transcarbamylase deficiency (OTC-D), and those in the hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome subgroup, height z-score was positively associated with patients' plasma L-leucine levels. In those with argininosuccinate synthetase deficiency (ASS-D) and argininosuccinate lyase deficiency (ASL-D), height was positively associated with patients' plasma L-valine levels.

CONCLUSION

Plasma L-arginine and L-valine levels in MMA/PA patients and plasma L-leucine and L-valine levels in UCD patients, as well as the protein-to-energy prescription ratio in both groups were positively associated with height. Optimization of these plasma amino acid levels is essential to support normal growth and increase protein tolerance in these disorders. Consequently this could improve the protein-to-energy intake ratio.

Acute L-Arginine supplementation does not affect red blood cell aggregation and deformability during high intensity interval exercise in healthy men

BACKGROUND

L-Arginine, the precursor of NO might be involved in improving the cardiovascular disorders via regulation of functional properties of erythrocytes.

OBJECTIVE

This study investigated the effects of L-Arginine supplementation on responses of red blood cell (RBC) properties to high intensity interval exercise (HIIE).

METHODS

Ten overweight healthy men participated voluntarily in the study and performed two HIIE trials with and without L-Arginine in two separate weeks. The HIIE protocol included 12 intervals of 3-min encompassed 1-min running at 100% of vVO2max and 2-min active recovery at 40% of vVO2max. Three blood samples were taken before and after supplementation, and immediately after exercise; and were used to measure red blood cell properties.

RESULTS

The HIIE protocol increased hematocrit, hemoglobin and lactate significantly (P < 0.05), but had no significant effect on RBC aggregation, RBC deformability, and fibrinogen concentration. When data were compared for two trials no significant differences between the responses of RBC properties to two HIIE protocols were detected (P > 0.05), whereas the increases in lactate concentration following HIIE was significantly lower in L-Arginine than placebo trial (P < 0.05).

CONCLUSIONS

It is concluded that L-Arginine consumption prior to HIIE does not lead to any improvement in RBC properties during HIIE in overweight healthy men.

Plasma asymmetric dimethylarginine concentrations are not related to differences in maximal oxygen uptake in endurance trained and untrained men

NEW FINDINGS

What is the central question of this study? Is there an association of plasma concentration of asymmetric dimethylarginine, which is related to exercise capacity in patients with cardiovascular diseases, with oxygen delivery and subsequently exercise capacity in healthy subjects in the absence of the potentially confounding influence of inflammation and oxidative stress? What is the main finding and its importance? Plasma asymmetric dimethylarginine concentrations are not related to exercise capacity in healthy subjects, while O₂ delivery in the working skeletal muscle during the maximal graded-exercise test is not associated with any of the l-arginine analogues. ADMA alone does not play a crucial role in local muscle perfusion and in maintaining exercise capacity.

ABSTRACT

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide (NO) synthesis that could limit oxygen (O₂ ) delivery in the working skeletal muscles by altering endothelium-dependent vasodilatation. Exercise capacity is associated with plasma ADMA concentrations in patients with cardiovascular diseases, but this issue has still not been investigated in healthy subjects. We aimed to determine whether plasma ADMA concentrations were negatively associated with exercise capacity in young healthy male subjects. Ten men with maximal oxygen uptake ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:mrow><mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> <mml:mi>max</mml:mi> </mml:mrow> </mml:msub> </mml:math> ) > 65 mL kg^-1  min^-1 were included in the high exercise capacity group (HI-FIT), and 10 men with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:mrow><mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> <mml:mi>max</mml:mi> </mml:mrow> </mml:msub> </mml:math>  < 45 mL kg^-1  min^-1 were included in the low exercise capacity group (LO-FIT). Plasma ADMA and other l-arginine analogue concentrations were measured before and after a maximal graded-exercise test by liquid chromatography-tandem mass spectrometry. Microvascular O₂ delivery during exercise was estimated through the pattern from the sigmoid model of muscle deoxygenation in the vastus lateralis measured by near infrared spectroscopy. <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mover><mml:mi>V</mml:mi> <mml:mo>̇</mml:mo></mml:mover> <mml:mrow><mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> <mml:mi>max</mml:mi> </mml:mrow> </mml:msub> </mml:math> was 60% higher in the HI-FIT group (median: 70.2 mL kg^-1  min^-1 ; IQR: 68.0-71.9 mL kg^-1  min^-1 ) than in the LO-FIT group (median: 43.8 mL kg^-1  min^-1 ; IQR: 34.8-45.3 mL kg^-1  min^-1 ). Plasma ADMA concentrations did not differ between the LO-FIT and HI-FIT groups before (0.50 ± 0.06 vs. 0.54 ± 0.07 μmol L^-1 , respectively) and after the maximal incremental exercise test (0.49 ± 0.08 vs. 0.55 ± 0.03 μmol L^-1 , respectively). There was no significant association of plasma ADMA concentrations with the pattern of local muscle deoxygenation and exercise capacity. Exercise capacity and microvascular O₂ delivery are not related to plasma ADMA concentrations in young healthy male subjects. Our findings show that ADMA does not play a crucial role in local muscle perfusion and in maintaining exercise capacity without pathological conditions.

Resistance training and L-arginine supplementation are determinant in genomic stability, cardiac contractility and muscle mass development in rats

L-arginine supplementation has been related to increased maximum strength and improvement of hemodynamic parameters in several diseases. The aim of our study was to evaluate the effect of L-arginine supplementation and resistance training on muscle mass, hemodynamic function and DNA damage in healthy rats subjected to a low-arginine concentration diet. Twenty three Wistar rats (290-320g) were divided into 4 groups: Sedentary (SED-Arg, n = 6), Sedentary+Arg (SED+Arg, n = 6), Resistance Training (RT-Arg, n = 5), Resistance Training+Arg (RT+Arg, n = 6). Trained animals performed resistance training protocol in a squat apparatus adapted for rats (4 sets of 10–12 repetitions, 90s of interval, 4x/week, 65–75% of One Maximum Repetition, for 8 weeks). Comet assay was performed to measure DNA damage in leukocytes. The resistance training induced higher muscle mass in trained groups. The L-arginine supplementation increased both gastrocnemius and left ventricle to body mass ratio and increased left ventricle contractility without changing hemodynamic variables. The SED+Arg group showed higher concentration of extracellular heat shock protein 72 (eHSP72) and total testosterone, as well as lower uric acid concentration in blood versus SED-Arg group. The administration of isolated L-arginine supplementation and its association with resistance training promoted less damage in leukocytes DNA. In conclusion, the L-arginine supplementation showed synergistic effect with resistance training regarding leukocyte genomic stability in a low-L-arginine diet scenario.

Dietary arginine affects growth, gut morphology, oxidation resistance and immunity of hybrid grouper (Epinephelus fuscoguttatus♀×Epinephelus lanceolatus♂) juveniles

An 8-week growth trial was conducted to evaluate the effects of dietary arginine (Arg) levels on growth, gut morphology, oxidation resistance and immunity of hybrid grouper (Epinephelus fuscoguttatus♀×Epinephelus lanceolatus♂) juveniles. Seven isoenergetic (1465 kJ (350 kcal)/100-g DM), isoproteic (53·5 % of DM) and isolipidic (7 % of DM) experimental diets were formulated to contain graded Arg levels ranging from 1·9 to 4·7 % (dry weight) at approximately 0·5 % increments. Each diet was randomly assigned to triplicate groups of 16 juvenile fish (average initial body weight: 11·7 (sd 0·1) g) and was administered twice daily (08.00 and 16.00 hours). After the growth trial, all remaining fish were fed their prescribed diets for 2 d and then exposed to 4·5 mg Cu2+/l water for 36 h. Results showed that growth performance and feed utilisation of experimental fish were significantly affected by different dietary Arg levels. Weight gain % (WG%) of fish was increased as dietary Arg increased, reaching a peak value at 3·8 % dietary Arg level, and when dietary Arg level increased to 4·7 % WG% was reduced. Fish fed 1·9 and 2·2 % dietary Arg levels had higher daily feed intake compared with fish fed other dietary Arg levels. Feed conversion ratios in fish fed 1·9, 2·2, 2·7 and 4·7 % dietary Arg levels were higher than those in fish fed 3·1, 3·8 and 4·1 % dietary Arg levels. Protein efficiency ratio and protein productive value (PPV) increased with an increase in dietary Arg, up to a peak value at 3·8 % dietary Arg level, above which these parameters declined. On the basis of quadratic regression analysis of weight gain % (WG%) or PPV against dietary Arg levels, the optimal dietary Arg requirement for hybrid grouper was estimated to be 3·65 %. Fish fed 3·8 % dietary Arg had higher whole-body and muscle protein contents compared with fish fed other dietary Arg levels. Fish fed 3·8 and 4·1 % dietary Arg levels had higher levels of mRNA for insulin-like growth factor-I and target of rapamycin in the liver compared with fish fed other dietary Arg levels. Hepatic S6 kinase 1 mRNA expression in fish fed 3·8 % dietary Arg level was higher than that in fish fed any of the other dietary Arg levels. Gut morphology, hepatic antioxidant indices and immune indices in serum and head kidney were significantly influenced by dietary Arg levels. In conclusion, the optimal dietary Arg requirement for hybrid grouper was estimated to be 3·65 %, and suitable dietary Arg supplementations improved gut morphology and oxidation resistance of hybrid grouper.

Effect of l-arginine addition on long-term storability of ram semen

This study was conducted to investigate the effect of l-arginine addition on long-term storability of ram semen. Six Akkaraman rams were used as material. Semen samples were collected. Pooled samples were diluted and were divided into six equal aliquots. While aliquot 1 was kept as control, the stock solutions including 0.1, 0.5, 1, 5 and 10 mm l-arginine were added to other aliquots. All aliquots were routinely frozen in 0.25-ml straws at -130°C liquid nitrogen vapour and stored in liquid nitrogen -196°C until being analysed. The equilibrated and thawed sperm motility, membrane integrity and arginase activity were evaluated. While the 10 mm l-arginine supplementation significantly (p < .001) decreased equilibrated sperm motility, the 5 mm significantly (p < .05) increased the membrane integrity and arginase activity in comparison with the control group. The motility (p < .001) and membrane integrity (p < .01) were determined to be highest in 0.5 mm group, while significant reductions were observed in motility (p < .001) of 10 mm group and arginase activity (p < .05) of 1, 10 mm groups as compared to the control group. It was concluded that in vitro addition of 0.5 mm l-arginine to ram semen may be useful, but 10 mm may be harmful to spermatozoa quality during long-term storage.

Decreased diabetes risk over 9 year after 18-month oral L-arginine treatment in middle-aged subjects with impaired glucose tolerance and metabolic syndrome (extension evaluation of L-arginine study)

Purpose

This study aimed to determine whether l-arginine supplementation lasting for 18 months maintained long-lasting effects on diabetes incidence, insulin secretion and sensitivity, oxidative stress, and endothelial function during 108 months among subjects at high risk of developing type 2 diabetes.

Methods

One hundred and forty-four middle-aged subjects with impaired glucose tolerance and metabolic syndrome were randomized in 2006 to an l-arginine supplementation (6.4 g orally/day) or placebo therapy lasting 18 months. This period was followed by a 90-month follow-up. The primary outcome was a diagnosis of diabetes during the 108 month study period. Secondary outcomes included changes in insulin secretion (proinsulin/c-peptide ratio), insulin sensitivity (IGI/HOMA-IR), oxidative stress (AOPPs), and vascular function. After the 18 month participation, subjects that were still free of diabetes and willing to continue their participation (104 subjects) were further followed until diabetes diagnosis, with a time span of about 9 years from baseline.

Results

Although results derived from the 18 month of the intervention study demonstrated no differences in the probability of becoming diabetics, at the end of the study, the cumulative incidence of diabetes was of 40.6% in the l-arginine group and of 57.4% in the placebo group. The adjusted HR for diabetes (l-arginine vs. placebo) was 0.66; 95% CI 0.48, 0.91; p < 0.02). Proinsulin/c-peptide ratio (p < 0.001), IGI/HOMA-IR (p < 0.01), and AOPP (p < 0.05) levels were ameliorated in l-arginine compared to placebo.

Conclusions

These results may suggest that the administration of l-arginine could delay the development of T2DM for a long period. This effect could be mediated, in some extent, by l-arginine-induced reduction in oxidative stress.

Argininosuccinate synthase 1 is an intrinsic Akt repressor transactivated by p53

The transcription factor p53 is at the core of a built-in tumor suppression system that responds to varying degrees of stress input and is deregulated in most human cancers. Befitting its role in maintaining cellular fitness and fidelity, p53 regulates an appropriate set of target genes in response to cellular stresses. However, a comprehensive understanding of this scheme has not been accomplished. We show that argininosuccinate synthase 1 (ASS1), a citrulline-aspartate ligase in de novo arginine synthesis pathway, was directly transactivated by p53 in response to genotoxic stress, resulting in the rearrangement of arginine metabolism. Furthermore, we found that x-ray irradiation promoted the systemic induction of Ass1 and concomitantly increased plasma arginine levels in p53^+/+ mice but not in p53^-/- mice. Notably, Ass1^+/- mice exhibited hypersensitivity to whole-body irradiation owing to increased apoptosis in the small intestinal crypts. Analyses of ASS1-deficient cells generated using the CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 (CRISPR-associated 9) system revealed that ASS1 plays a pivotal role in limiting Akt phosphorylation. In addition, aberrant activation of Akt resulting from ASS1 loss disrupted Akt-mediated cell survival signaling activity under genotoxic stress. Building on these results, we demonstrated that p53 induced an intrinsic Akt repressor, ASS1, and the perturbation of ASS1 expression rendered cells susceptible to genotoxic stress. Our findings uncover a new function of p53 in the regulation of Akt signaling and reveal how p53, ASS1, and Akt are interrelated to each other.

Modulatory effects of arginine, glutamine and branched-chain amino acids on heat shock proteins, immunity and antioxidant response in exercised rats

Heat shock proteins (HSPs) are endogenous proteins whose function is to maintain the cell's tolerance to insult, including intense exercise.

Arginine Relieves the Inflammatory Response and Enhances the Casein Expression in Bovine Mammary Epithelial Cells Induced by Lipopolysaccharide

As one of functional active amino acids, L-arginine holds a key position in immunity. However, the mechanism that arginine modulates cow mammary inflammatory response in ruminant is unclear. Therefore, this study was conducted to investigate the effects of L-arginine on inflammatory response and casein expression after challenging the bovine mammary epithelial cells (BMECs) with lipopolysaccharide (LPS). The cells were divided into four groups, stimulated with or without LPS (10 μg/mL) and treated with or without arginine (100 μg/mL) for 12 h. The concentration of proinflammatory cytokines, inducible nitric oxide synthase (iNOS), mammalian target of rapamycin (mTOR), and Toll-like receptor 4 (TLR4) signaling pathways as well as the casein was determined. The results showed that arginine reduced the LPS-induced production like IL-1β, IL-6, TNF-α, and iNOS. Though the expression of NF-κB was attenuated and the mTOR signaling pathway was upregulated, arginine had no effect on TLR4 expression. In addition, our results show that the content of β-casein and the total casein were enhanced after arginine was supplemented in LPS-induced BMECs. In conclusion, arginine could relieve the inflammatory reaction induced by LPS and enhance the concentration of β-casein and the total casein in bovine mammary epithelial cells.

Arginyl-glutamine dipeptide attenuates experimental colitis by enhancing antioxidant function and inhibiting nuclear factor-kappaB

This study aimed to investigate the effect and underlying mechanism of Arginyl-glutamine (AG) dipeptide on dextran sulfate sodium (DSS)-induced colitis byin vivoandin vitromodels.