Oxidative stress on mitochondrial antioxidant defense system in the aging process: Role of dl-α-lipoic acid and l-carnitine

Metabolic memory: mechanisms and diseases

Metabolic diseases and their complications impose health and economic burdens worldwide. Evidence from past experimental studies and clinical trials suggests our body may have the ability to remember the past metabolic environment, such as hyperglycemia or hyperlipidemia, thus leading to chronic inflammatory disorders and other diseases even after the elimination of these metabolic environments. The long-term effects of that aberrant metabolism on the body have been summarized as metabolic memory and are found to assume a crucial role in states of health and disease. Multiple molecular mechanisms collectively participate in metabolic memory management, resulting in different cellular alterations as well as tissue and organ dysfunctions, culminating in disease progression and even affecting offspring. The elucidation and expansion of the concept of metabolic memory provides more comprehensive insight into pathogenic mechanisms underlying metabolic diseases and complications and promises to be a new target in disease detection and management. Here, we retrace the history of relevant research on metabolic memory and summarize its salient characteristics. We provide a detailed discussion of the mechanisms by which metabolic memory may be involved in disease development at molecular, cellular, and organ levels, with emphasis on the impact of epigenetic modulations. Finally, we present some of the pivotal findings arguing in favor of targeting metabolic memory to develop therapeutic strategies for metabolic diseases and provide the latest reflections on the consequences of metabolic memory as well as their implications for human health and diseases.

Comparative efficacy of silibinin and nano-silibinin on lead poisoning in Male Wistar rats

Lead (Pb) is an environmental neurotoxin that can lead to toxicity. It has shown that tissues can be exposed to oxidative stress in lead poisoning. Since silymarin is a natural agent with antioxidant effects, this study aimed to investigate the antioxidant and chelation effects of silibinin and nano-silibinin on the oxidative stress status in lead-poisoned rats. Sixty male Wistar rats randomly divided into ten groups (n = 6). Control and Pb groups treated with or without silibinin and nano-silibinin for six days. Following measuring of weight and blood lead levels, biochemical antioxidant parameters evaluated. Finally, a histopathological examination of the liver performed. In this experiment, silibinin and more efficiently nano-silibinin prevented weight loss and blood lead level elevation induced by lead. Also, they increased the attenuated levels of superoxide dismutase (SOD) activity, catalase (CAT), total thiol molecules (TTM), glutathione (GSH), and total antioxidant capacity (TAC). Lead-induced elevation of lipid peroxidation products (MDA) and nitric oxide (NO) normalized to the standard level in silibinin and especially nano-silibinin groups. These data suggested that silibinin and especially nano-silibinin can decrease blood lead levels and prevent weight loss and oxidative stress in the lead-poisoned rat's model.

Rag1 immunodeficiency-induced early aging and senescence in zebrafish are dependent on chronic inflammation and oxidative stress

In mammals, recombination activating gene 1 (RAG1) plays a crucial role in adaptive immunity, generating a vast range of immunoglobulins. Rag1^−/− zebrafish (Danio rerio) are viable and reach adulthood without obvious signs of infectious disease in standard nonsterile conditions, suggesting that innate immunity could be enhanced to compensate for the lack of adaptive immunity. By using microarray analysis, we confirmed that the expression of immunity‐ and apoptosis‐related genes was increased in the rag1^−/− fish. This tool also allows us to notice alterations of the DNA repair and cell cycle mechanisms in rag1^−/− zebrafish. Several senescence and aging markers were analyzed. In addition to the lower lifespan of rag1^−/− zebrafish compared to their wild‐type (wt) siblings, rag1^−/− showed a higher incidence of cell cycle arrest and apoptosis, a greater amount of phosphorylated histone H2AX, oxidative stress and decline of the antioxidant mechanisms, an upregulated expression and activity of senescence‐related genes and senescence‐associated β‐galactosidase, respectively, diminished telomere length, and abnormal self‐renewal and repair capacities in the retina and liver. Metabolomic analysis also demonstrated clear differences between wt and rag1^−/− fish, as was the deficiency of the antioxidant metabolite l‐acetylcarnitine (ALCAR) in rag1^−/− fish. Therefore, Rag1 activity does not seem to be limited to V(D)J recombination but is also involved in senescence and aging. Furthermore, we confirmed the senolytic effect of ABT‐263, a known senolytic compound and, for the first time, the potential in vivo senolytic activity of the antioxidant agent ALCAR, suggesting that this metabolite is essential to avoid premature aging.

Mechanism of valproic acid-induced Fanconi syndrome involves mitochondrial dysfunction and oxidative stress in rat kidney

AIM

Drug-induced kidney proximal tubular injury and renal failure (Fanconi syndrome; FS) is a clinical complication. Valproic acid (VPA) is among the FS-inducing drugs. The current investigation was designed to evaluate the role of mitochondrial dysfunction and oxidative stress in VPA-induced renal injury.

METHODS

Animals received VPA (250 and 500 mg/kg, i.p., 15 consecutive days). Serum biomarkers of kidney injury and markers of oxidative stress were assessed. Moreover, kidney mitochondria were isolated and mitochondrial indices, including succinate dehydrogenase activity (SDA), mitochondrial depolarization, mitochondrial permeability transition pore (MPP), reactive oxygen species (ROS), lipid peroxidation (LPO), mitochondrial glutathione, and ATP were determined.

RESULTS

Valproic acid-treated animals developed biochemical evidence of FS as judged by elevated serum gamma-glutamyl transferase (γ-GT), alkaline phosphatase (ALP), creatinine (Cr), and blood urea nitrogen (BUN) along with hypokalaemia, hypophosphataemia, and a decrease in serum uric acid. VPA caused an increase in kidney ROS and LPO. Renal GSH reservoirs were depleted and tissue antioxidant capacity decreased in VPA-treated animals. Renal tubular interstitial nephritis, tissue necrosis, and atrophy were also evident in VPA-treated rats. Mitochondrial parameters including SDA, MMP, GSH, ATP and MPP were decreased and mitochondrial ROS and LPO were increased with VPA treatment. It was found that carnitine (100 mg/kg, i.p.) mitigated VPA adverse effects towards the kidney.

CONCLUSIONS

These data suggest that mitochondrial dysfunction and oxidative stress contributed to the VPA-induced FS. On the other hand, carnitine could be considered a potentially safe and effective therapeutic option in attenuating VPA-induced renal injury.

The genomic impact of historical hybridization with massive mitochondrial DNA introgression

BACKGROUND

The extent to which selection determines interspecific patterns of genetic exchange enlightens the role of adaptation in evolution and speciation. Often reported extensive interspecific introgression could be selection-driven, but also result from demographic processes, especially in cases of invasive species replacements, which can promote introgression at their invasion front. Because invasion and selective sweeps similarly mold variation, population genetics evidence for selection can only be gathered in an explicit demographic framework. The Iberian hare, Lepus granatensis, displays in its northern range extensive mitochondrial DNA introgression from L. timidus, an arctic/boreal species that it replaced locally after the last glacial maximum. We use whole-genome sequencing to infer geographic and genomic patterns of nuclear introgression and fit a neutral model of species replacement with hybridization, allowing us to evaluate how selection influenced introgression genome-wide, including for mtDNA.

RESULTS

Although the average nuclear and mtDNA introgression patterns contrast strongly, they fit a single demographic model of post-glacial invasive replacement of timidus by granatensis. Outliers of elevated introgression include several genes related to immunity, spermatogenesis, and mitochondrial metabolism. Introgression is reduced on the X chromosome and in low recombining regions.

CONCLUSIONS

General nuclear and mtDNA patterns of introgression can be explained by purely demographic processes. Hybrid incompatibilities and interplay between selection and recombination locally modulate levels of nuclear introgression. Selection promoted introgression of some genes involved in conflicts, either interspecific (parasites) or possibly cytonuclear. In the latter case, nuclear introgression could mitigate the potential negative effects of alien mtDNA on mitochondrial metabolism and male-specific traits.

An evaluation of the protective role of Ficus racemosa Linn. in streptozotocin-induced diabetic neuropathy with neurodegeneration

Objective:

Ficus racemosa (FR) is one of the herbs mentioned in the scriptures of the Ayurveda as Udumbara with high medicinal value. The objective of this study was to estimate the protective effect of FR against streptozotocin (STZ) induced diabetic neuropathy with neurodegeneration (DNN).

Materials and Methods:

Diabetes was induced in Wistar rats with STZ and were divided into six groups namely diabetic vehicle control, FR (four) and glibenclamide (one) treated rats; while one group was of normal control rats. After the 4^th week of diabetes, induction treatment was started for further 28 days (5^th to 8^th week) with FR aqueous extract (250 mg/kg and 500 mg/kg) and ethanolic extract (200 mg/kg and 400 mg/kg). Investigation of DNN was carried out through biochemical and behavioral parameter assessment in rats.

Results:

Study showed a significant fall in glycosylated hemoglobin (HbA1c) and blood glucose level by the treatment of FR in diabetic rats. Antioxidant potential of FR showed a great rise in superoxide dismutase, catalase content and reduction observed in serum nitrite level; while significant fall in lipid peroxidation level and of C-reactive protein was observed in FR treated diabetic rats. Further FR treated diabetic rats also showed marked improvement in tail flick latency, pain threshold, the rise in locomotion and fall latency period.

Conclusion:

Treatment with FR shows protection in the multiple pathways of DNN by improving blood glucose, HbA1c, biochemical, and behavioral parameters, which suggest the protective role of FR in the reversal of DNN.

Experimental strategies towards increasing intracellular mitochondrial activity in oocytes: A systematic review

PURPOSE

The mitochondrial complement is critical in sustaining the earliest stages of life. To improve the Assisted Reproductive Technology (ART), current methods of interest were evaluated for increasing the activity and copy number of mitochondria in the oocyte cell.

METHODS

This covered the researches from 1966 to September 2015.

RESULTS

The results provided ten methods that can be studied individually or simultaneously.

CONCLUSION

Though the use of these techniques generated great concern about heteroplasmy observation in humans, it seems that with study on these suggested methods there is real hope for effective treatments of old oocyte or oocytes containing mitochondrial problems in the near future.

Conductive Paper with Antibody-Like Film for Electrical Readings of Biomolecules

This work reports a novel way of producing an inexpensive substrate support to assemble a sensing film, designed for the electrical transduction of an intended biomolecule. The support uses cellulose paper as substrate, made hydrophobic with solid wax and covered by a home-made conductive ink having graphite as core material. The hydrophobicity of the paper was confirmed by contact angle measurements and the conductive ink composition was optimized with regard to its adhesion, conductivity, and thermal stability. This support was further modified targeting its application in quantitative analysis. Carnitine (CRT) was selected as target compound, a cancer biomarker. The recognition material consisted of an antibody-like receptor film for CRT, tailored on the support and prepared by electrically-sustained polymerization of 3,4-ethylenedioxythiophene (EDOT) or dodecylbenzenesulfonic acid (DBS). Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy analysis confirmed the presence of the polymeric film on the support, and the performance of the devices was extensively evaluated with regard to linear response ranges, selectivity, applicability, and reusability. Overall, the paper-based sensors offer simplicity of fabrication, low cost and excellent reusability features. The design could also be extended to other applications in electrical-based approaches to be used in point-of-care (POC).

Nephron Toxicity Profiling via Untargeted Metabolome Analysis Employing a High Performance Liquid Chromatography-Mass Spectrometry-based Experimental and Computational Pipeline

Untargeted metabolomics has the potential to improve the predictivity of in vitro toxicity models and therefore may aid the replacement of expensive and laborious animal models. Here we describe a long term repeat dose nephrotoxicity study conducted on the human renal proximal tubular epithelial cell line, RPTEC/TERT1, treated with 10 and 35 μmol·liter(-1) of chloroacetaldehyde, a metabolite of the anti-cancer drug ifosfamide. Our study outlines the establishment of an automated and easy to use untargeted metabolomics workflow for HPLC-high resolution mass spectrometry data. Automated data analysis workflows based on open source software (OpenMS, KNIME) enabled a comprehensive and reproducible analysis of the complex and voluminous metabolomics data produced by the profiling approach. Time- and concentration-dependent responses were clearly evident in the metabolomic profiles. To obtain a more comprehensive picture of the mode of action, transcriptomics and proteomics data were also integrated. For toxicity profiling of chloroacetaldehyde, 428 and 317 metabolite features were detectable in positive and negative modes, respectively, after stringent removal of chemical noise and unstable signals. Changes upon treatment were explored using principal component analysis, and statistically significant differences were identified using linear models for microarray assays. The analysis revealed toxic effects only for the treatment with 35 μmol·liter(-1) for 3 and 14 days. The most regulated metabolites were glutathione and metabolites related to the oxidative stress response of the cells. These findings are corroborated by proteomics and transcriptomics data, which show, among other things, an activation of the Nrf2 and ATF4 pathways.

Allicin protects rat cardiomyoblasts (H9c2 cells) from hydrogen peroxide-induced oxidative injury through inhibiting the generation of intracellular reactive oxygen species

Oxidative stress is considered an important factor that promotes cell death in response to a variety of pathophysiological conditions. This study investigated the antioxidant properties of allicin, the principle ingredient of garlic, on preventing oxidative stress-induced injury. The antioxidant capacities of allicin were measured by using 1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay and hydrogen peroxide (H(2)O(2))-induced cell damage on H9c2 cardiomyoblasts. Allicin (0.3-10 μM) pre-incubation could concentration-dependently attenuate the intracellular reactive oxygen species (ROS) increase induced by H(2)O(2) on H9c2 cells. It could also protect H9c2 cells against H(2)O(2)-induced cell damage. However, the DPPH free radical scavenging activity of allicin was shown to be low. Therefore, it is believed that the protective effect of allicin on H9c2 cells could inhibit intracellular ROS production instead of scavenging extracellular H(2)O(2) or free radicals. For the observed protective effect on H9c2 cells, allicin might also be effective in reducing free radical-induced myocardial cell death in ischemic condition.

Nanocapsulated quercetin downregulates rat hepatic MMP-13 and controls diethylnitrosamine-induced carcinoma

AIMS

The aims of our work were to investigate the controlling role and the efficacy of nanocapsulated quercetin drug delivery system on the decrement of inflammatory mediators such as MMP-13 in diethyl nitrosamine (DEN)-induced hepatocarcinogenesis.

MATERIALS & METHODS

Hepatocellular carcinoma was developed in the Swiss albino rats by the exposure of DEN. DEN administration caused the generation of reactive oxygen species, upregulation of TNF-α, IL-6, activation of MMP-13, severe oxidative damage, hyperplastic nodules with preneoplastic lesions and the histopathological changes in rat liver.

RESULTS & CONCLUSION

Nanocapsulated quercetin treatment restricted all alterations in DEN-mediated development of hepatocarcinogenesis. Therefore, it may be concluded that nanocapsulated quercetin may be accepted as a potent therapeutic formulation in preventing DEN-mediated hepatocarcinogenesis.

Huperzine A ameliorates cognitive deficits and oxidative stress in the hippocampus of rats exposed to acute hypobaric hypoxia

Acute exposure to high altitudes can cause neurological dysfunction due to decreased oxygen availability to the brain. In this study, the protective effects of Huperzine A on cognitive deficits along with oxidative and apoptotic damage, due to acute hypobaric hypoxia, were investigated in male Sprague-Dawley rats. Rats were exposed to simulated hypobaric hypoxia at 6,000 m in a specially fabricated animal decompression chamber while receiving daily Huperzine A orally at the dose of 0.05 or 0.1 mg/kg body weight. After exposure to hypobaric hypoxia for 5 days, rats were trained in a Morris Water Maze for 5 consecutive days. Subsequent trials revealed Huperzine A supplementation at a dose of 0.1 mg/kg body weight restored spatial memory significantly, as evident from decreased escape latency and path length to reach the hidden platform, and the increase in number of times of crossing the former platform location and time spent in the former platform quadrant. In addition, after exposure to hypobaric hypoxia, animals were sacrificed and biomarkers of oxidative damage, such as reactive oxygen species, lipid peroxidation, lactate dehydrogenase activity, reduced glutathione, oxidized glutathione and superoxide dismutase were studied in the hippocampus. Expression levels of pro-apoptotic proteins (Bax, caspase-3) and anti-apoptotic protein (Bcl-2) of hippocampal tissues were evaluated by Western blotting. There was a significant increase in oxidative stress along with increased expression of apoptotic proteins in hypoxia exposed rats, which was significantly improved by oral Huperzine A at 0.1 mg/kg body weight. These results suggest that supplementation with Huperzine A improves cognitive deficits, reduces oxidative stress and inhibits the apoptotic cascade induced by acute hypobaric hypoxia.

Hesperidin-mediated expression of Nrf2 and upregulation of antioxidant status in senescent rat heart

OBJECTIVES

Oxidative stress is recognized as a key element responsible for the development of age-related pathologies. A declining endogenous defence system during senescence dictates the need for supplementation with exogenous antioxidants through diet. Hesperidin is a naturally occurring flavonone present in citrus fruits and has been shown to have many biological properties, including antioxidant activity. We investigated whether hesperidin supplementation could be valuable in protecting cardiac tissue of aged rats against age-related increase in oxidative stress, as well as the mechanism by which it can boost the antioxidant status of the cell.

METHODS

The activity of antioxidant enzymes, mRNA expression of Nrf2, protein levels of superoxide dismutase and catalase were measured using standard protocols.

KEY FINDINGS

Hesperidin treatment effectively protected aged rat heart by increasing the activity of enzymic antioxidants. Hesperidin upregulated the protein levels of nuclear factor erythroid 2-related factor 2, which is responsible for maintaining the antioxidant status of the cell.

CONCLUSIONS

Hesperidin could be useful in protecting cardiomyocytes against age-related increase in oxidative stress mediated by Nrf2 upregulation.

Evaluation of Anti-Oxidant Capacity of Root of Scutellaria baicalensis Georgi, in Comparison with Roots of Polygonum multiflorum Thunb and Panax ginseng CA Meyer

In Chinese communities, regular consumption of Chinese-medicated diets (CMD) (usually in the form of soup) is a traditional practice to promote health and prevent disease development. The overall improvement of health conditions is believed to be correlated with the anti-oxidant potentials of these herbs. Huangqin, roots of Scutellaria baicalensis Georgi (Lamiaceae), is one of the herbs commonly used in CMD. In this study, the anti-oxidant capacities of Huangqin extracts (water, ethanol and ether extracts) were evaluated and compared to commonly used CMD herbs, Heshouwu, roots of Polygonum multiflorum Thunb (Polygonaceae) and Renshen (or Ginseng), roots of Panax ginseng CA Meyer (Araliaceae). The anti-oxidant capacities were measured by using both cell-free assay [ferric reducing/anti-oxidant power (FRAP)] and biological methods [2,2'-azobis–(2-amidinopropane) (AAPH)-induced haemolysis assay and H2O2 -induced cell damage on H9C2 cells]. Additionally, the total phenolic content was measured using Folin-Ciocalteu methods. Water extract of Huangqin has the highest anti-oxidant activities compared to the ethanol and ether extracts. A positive relationship between the anti-oxidant effects and total phenolic contents of extracts was demonstrated. This shows that Huangqin could be an effective dietary anti-oxidant that can be consumed regularly as a functional food for the prevention of oxidant/free radical-related diseases.

Dietary lipoic acid influences antioxidant capability and oxidative status of broilers

The effects of lipoic acid (LA) on the antioxidant status of broilers were investigated. Birds (1 day old) were randomly assigned to four groups and fed corn-soybean diets supplemented with 0, 100, 200, 300 mg/kg LA, respectively. The feeding program included a starter diet from 1 to 21 days of age and a grower diet from 22 to 42 days of age. Serum, liver and muscle samples were collected at 42 days of age. For antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity in serum, liver and breast muscle significantly increased in chickens fed with LA. The concentration of malondiadehyde (MDA), an indicator of lipid peroxidation, was significantly lower in serum, liver and leg muscle in birds that received LA than in the control group. Treatments with LA significantly increased glutathione (GSH) content in liver and increased α-tocopherol content in leg muscle as compared to the control. These results indicate that dietary supplementation with 300 mg/kg LA may enhance antioxidant capability and depress oxidative stress in broilers.

Early changes in oxidative stress markers in a rat model of acute stress: effect of l-carnitine on the striatum

This work focuses on the effect of acute stress on different markers of oxidative stress and mitochondrial dysfunction in the rat striatum. In addition, the effect of a single dose of l-carnitine (l-CAR, 300 mg/kg, i.p.) was evaluated in these animals. Immobilization (restraint) stress was induced to rats for 24 hr. The levels of lipid peroxidation (LP) and mitochondrial function (MF), as well as the superoxide dismutase (SOD) activity and content and reduced glutathione (GSH) levels, were all measured in striatal samples of animals subjected to stress. Our results indicate that acute stress is able to increase the striatal LP and reduced the levels of MF, while significantly lowered the manganese superoxide dismutase (Mn-SOD) activity. No changes were observed in the total striatal content of SOD, nor in GSH levels, but serum corticosterone content was increased by stress. l-CAR exhibited partial protective effects on the immobilized group, reducing the striatal LP and recovering the striatal MF and Mn-SOD activity. Our results suggest that acute restraint stress brings an accurate model for early pro-oxidant responses that can be targeted by broad-spectrum antioxidants like l-CAR.

Effect of POLY-MVA, a palladium alpha-lipoic acid complex formulation against declined mitochondrial antioxidant status in the myocardium of aged rats

Palladium alpha-lipoic acid formulation--'POLY-MVA' is found to enhance the activities of Krebs cycle dehydrogenases and respiratory complexes in the heart of aged rat. In this study, we aimed to evaluate the effect of POLY-MVA on the activities of antioxidant status in the heart mitochondria of aged rat. We determined the activities of manganese-superoxide dismutase (Mn SOD), catalase (CAT), glutathione peroxidase (GPx), and level of reduced GSH and lipid peroxidation in the heart mitochondria of aged rats, after administering POLY-MVA (0.05 ml/kg; equivalent to 0.38 mg complexed alpha-lipoic acid/kg) orally once daily for 30 days. DL-alpha-lipoic acid (0.38 mg/kg, p.o) treated for 30 days was kept as the positive control. We found that the antioxidant in the aged control was declined significantly than the young control. The formulation significantly (p<0.05) enhanced the activity of CAT and GPx compared to the aged control. The level of GSH was also significantly improved and the level of lipid peroxidation was decreased significantly (p<0.05) by POLY-MVA. The results indicate that POLY-MVA is effective to protect the age-linked decline of myocardial mitochondrial antioxidant status. The findings suggest the use of this formulation against myocardial aging.

Effect of propionyl-L-carnitine, L-arginine and nicotinic acid on the efficacy of vardenafil in the treatment of erectile dysfunction in diabetes

OBJECTIVE

The association of diabetes-related vascular damage and the role of metabolic factors in erectile dysfunction are well known in the literature. The compounds propionyl-L-carnitine (PLC), L-arginine (L-Arg) and nicotinic acid have numerous metabolic actions which have been reported to improve endothelial function. This study investigated the administration of the combination of these three compounds alone and in association with an inhibitor of 5-phosphodiesterase (5PDE), vardenafil, on endothelial function in diabetic patients with erectile dysfunction.

METHODS

A total of 40 patients aged between 50 and 60 years with insulin-dependent diabetes (IDDM) for 3-4 years were selected from 509 patients presenting with erectile dysfunction. The patients were randomly subdivided into four groups of ten to be treated for 12 weeks. Group A was administered one sachet each day of test formulation containing PLC, L-Arg and nicotinic acid (Ezerex); group B with one 20 mg capsule of vardenafil (Levitra) twice a week; group C was treated with one sachet each day of the test formulation plus vardenafil 20 mg twice a week. Group D was administered placebo capsules twice weekly. Endothelial function was evaluated by examining flow-mediated dilation (FMD) and erectile function was estimated with the International Index of Erectile Function (IIEF5) questionnaire in all subjects.

RESULTS

At the end of treatment group A showed an increment of 2 points in the IIEF5; group B showed an increment of 4 points; group C, the group which was administered all the treatments, showed an increment of 5 points, and group D, treated with placebo, showed no increment in the IIEF5.

CONCLUSION

Although there was a small number of subjects in this study the data suggest that the test formulation may improve the endothelial situation in diabetes. The test formulation together with vardenafil was better than the 5PDE inhibitor alone, but further studies are needed to confirm these findings.

Prophylaxis with alpha-lipoic acid against lipopolysaccharide-induced brain injury in rats

Introduction

Lipopolysaccharide (LPS) stimulates the synthesis and release of reactive oxygen species that play an important role in the pathogenesis of tissue injuries. In this study the effect of early administration of the antioxidant α-lipoic acid (α-LA) on brain lipid peroxidation, brain hydrogen peroxide (H₂O₂) concentration, and brain total sulfhydryl group (-SH group) content was evaluated in rats with endotoxic shock induced by administration of LPS (Escherichia coli 026:B6, 30 mg/kg i.v.)

Materials and Methods

Rats were treated intravenously with normal saline or α-LA (60 mg/kg) 30 min after LPS injection. After 5 h of observation, the animals were killed and their brains were isolated for the measurements.

Results

Injection of LPS alone resulted in the development of shock and oxidative stress, the latter indicated by a significant increase in brain concentrations of thiobarbituric acid-reacting substances (TBARS) and H₂O₂ and a decrease in total brain -SH group content. Administration of α-LA after the LPS challenge resulted in an increase in total -SH group content and a decrease in TBARS and H₂O₂ concentration in the brain tissue compared with the LPS group.

Conclusion

The results indicate that α-LA treatment effectively protected the brain tissue against endotoxin-induced oxidative stress. Administration of LA could be a useful adjunct to clinical application in the management of septic shock.

The combination of alpha-lipoic acid supplementation and aerobic exercise inhibits lipid peroxidation in rat skeletal muscles

We investigated the effect of DL-alpha-lipoic acid (LA) supplementation and regular aerobic exercise on the concentrations of malondialdehyde (MDA) and vitamin E, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx), and the levels of glutathione (GSH) in rat skeletal muscles (soleus and red gastrocnemius). For 8 weeks, rats (n = 7 per group) were (1) exercised on a treadmill for 30 min d(-1), (2) treated with supplemental LA, or (3) exercised and treated with supplemental LA. Control rats (n = 7) did not receive LA and were not exercised. DL-alpha-lipoic acid (100 mg kg(-1)) was administered daily as an oral supplement. The rats were exercised in a graded manner for 5 d wk(-1). The concentration of MDA in the soleus and red gastrocnemius was significantly lower in rats that exercised and received LA than in the other groups. Compared with the other groups, rats that exercised and received LA had a significantly higher vitamin E concentration in the soleus. The SOD and GPx activities in the soleus and red gastrocnemius were significantly higher in rats that exercised and received LA. These results suggest that LA supplementation combined with aerobic treadmill exercise inhibits lipid peroxidation in skeletal muscles. This effect was especially remarkable in the soleus, which is particularly sensitive to oxidative stress, as revealed by the increased vitamin E level and SOD and GPx activities.

Role of nitrosative stress in the pathogenesis of diabetic vascular dysfunction

Here we overview the role of reactive nitrogen species (nitrosative stress) and associated pathways in the pathogenesis of diabetic vascular complications. Increased extracellular glucose concentration, a principal feature of diabetes mellitus, induces a dysregulation of reactive oxygen and nitrogen generating pathways. These processes lead to a loss of the vascular endothelium to produce biologically active nitric oxide (NO), which impairs vascular relaxations. Mitochondria play a crucial role in this process: endothelial cells placed in increase extracellular glucose respond with a marked increase in mitochondrial superoxide formation. Superoxide, when combining with NO generated by the endothelial cells (produced by the endothelial isoform of NO synthase), leads to the formation of peroxynitrite, a cytotoxic oxidant. Reactive oxygen and nitrogen species trigger endothelial cell dysfunction through a multitude of mechanisms including substrate depletion and uncoupling of endothelial isoform of NO synthase. Another pathomechanism involves DNA strand breakage and activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP). PARP-mediated poly(ADP-ribosyl)ation and inhibition of glyceraldehyde-3-phosphate dehydrogenase importantly contributes to the development of diabetic vascular complications: it induces activation of multiple pathways of injury including activation of nuclear factor kappa B, activation of protein kinase C and generation of intracellular advanced glycation end products. Reactive species generation and PARP play key roles in the pathogenesis of 'glucose memory' and in the development of injury in endothelial cells exposed to alternating high/low glucose concentrations.

Role of nitrosative stress in the pathogenesis of diabetic vascular dysfunction

Here we overview the role of reactive nitrogen species (nitrosative stress) and associated pathways in the pathogenesis of diabetic vascular complications. Increased extracellular glucose concentration, a principal feature of diabetes mellitus, induces a dysregulation of reactive oxygen and nitrogen generating pathways. These processes lead to a loss of the vascular endothelium to produce biologically active nitric oxide (NO), which impairs vascular relaxations. Mitochondria play a crucial role in this process: endothelial cells placed in increase extracellular glucose respond with a marked increase in mitochondrial superoxide formation. Superoxide, when combining with NO generated by the endothelial cells (produced by the endothelial isoform of NO synthase), leads to the formation of peroxynitrite, a cytotoxic oxidant. Reactive oxygen and nitrogen species trigger endothelial cell dysfunction through a multitude of mechanisms including substrate depletion and uncoupling of endothelial isoform of NO synthase. Another pathomechanism involves DNA strand breakage and activation of the nuclear enzyme poly(ADP-ribose) polymerase (PARP). PARP-mediated poly(ADP-ribosyl)ation and inhibition of glyceraldehyde-3-phosphate dehydrogenase importantly contributes to the development of diabetic vascular complications: it induces activation of multiple pathways of injury including activation of nuclear factor kappa B, activation of protein kinase C and generation of intracellular advanced glycation end products. Reactive species generation and PARP play key roles in the pathogenesis of 'glucose memory' and in the development of injury in endothelial cells exposed to alternating high/low glucose concentrations.

Loss of cardioprotection with ageing

Not only the prevalence, but also the mortality due to ischaemic cardiovascular disease is higher in older than in young humans, and the demographic shift towards an ageing population will further increase the prevalence of age-related cardiovascular disease. In order to develop strategies aimed to limit reversible and irreversible myocardial damage in older patients, there is a need to better understand age-induced alterations in protein expression and cell signalling. Cardioprotective phenomena such as ischaemic and pharmacological pre and postconditioning attenuate ischaemia/reperfusion injury in young hearts. Whether or not pre and postconditioning are still effective in aged organs, animals, or patients, i.e. under conditions where such cardioprotection is most relevant, is still a matter of debate; most studies suggest a loss of protection in aged hearts. The present review discusses changes in protein expression and cell signalling important to ischaemia/reperfusion injury with myocardial ageing. The efficacy of cardioprotective manoeuvres, e.g. ischaemic pre and postconditioning in aged organs and animals will be discussed, and the development of strategies aimed to antagonize the age-induced loss of protection will be addressed.

L-carnitine supplementation and physical exercise restore age-associated decline in some mitochondrial functions in the rat

In mammals, during the aging process, an atrophy of the muscle fibers, an increase in body fat mass, and a decrease in skeletal muscle oxidative capacities occur. Compounds and activities that interact with lipid oxidative metabolism may be useful in limiting damages that occur in aging muscle. In this study, we evaluated the effect of L-carnitine and physical exercise on several parameters related to muscle physiology. We described that supplementing old rats with L-carnitine at 30 mg/kg body weight for 12 weeks (a) allowed the restoration of L-carnitine level in muscle cells, (b) restored muscle oxidative activity in the soleus, and (c) induced positive changes in body composition: a decrease in abdominal fat mass and an increase in muscle capabilities without any change in food intake. Moderate physical exercise was also effective in (a) limiting fat mass gain and (b) inducing an increase in the capacities of the soleus to oxidize fatty acids.

L-carnitine-L-tartrate promotes human hair growth in vitro

The trimethylated amino acid l-carnitine plays a key role in the intramitochondrial transport of fatty acids for beta-oxidation and thus serves important functions in energy metabolism. Here, we have tested the hypothesis that l-carnitine, a frequently employed dietary supplement, may also stimulate hair growth by increasing energy supply to the massively proliferating and energy-consuming anagen hair matrix. Hair follicles (HFs) in the anagen VI stage of the hair cycle were cultured in the presence of 0.5-50 microm of l-carnitine-l-tartrate (CT) for 9 days. At day 9, HFs treated with 5 microm or 0.5 microm of CT showed a moderate, but significant stimulation of hair shaft elongation compared with vehicle-treated controls (P < 0.05). Also, CT prolonged the duration of anagen VI, down regulated apoptosis (as measured by TUNEL assay) and up regulated proliferation (as measured by Ki67 immunohistology) of hair matrix keratinocytes (P < 0.5). By immunohistology, intrafollicular immunoreactivity for TGFbeta2, a key catagen-promoting growth factor, in the dermal papilla and TGF-beta II receptor protein in the outer root sheath and dermal papilla was down regulated. As shown by caspase activity assay, caspase 3 and 7, which are known to initiate apoptosis, are down regulated at day 2 and day 4 after treatment of HFs with CT compared with vehicle-treated control indicating that CT has an immediate protective effect on HFs to undergo programmed cell death. Our findings suggest that l-carnitine stimulates human scalp hair growth by up regulation of proliferation and down regulation of apoptosis in follicular keratinocytes in vitro. They further encourage one to explore topical and nutraceutical administration of l-carnitine as a well-tolerated, relatively safe adjuvant treatment in the management of androgenetic alopecia and other forms of hair loss.

Propionyl-L-Carnitine Prevents Age-Related Myocardial Remodeling in the Rabbit

Age-related cardiac remodeling is characterized by changes in myocardial structure, which include fibrosis (ie, increased collagen concentration). The pathogenetic mechanisms of age-related cardiac changes and possible pharmacologic interventions are still a matter of investigation. A morphometric analysis of collagen accumulation was performed in Sirius Red-stained left ventricular sections of 3-month-old and 5-6-year-old animals after a 9-month period of propionyl-L-carnitine treatment (PLC; 120 mg Kg(-1) day(-1) per os); aged rabbits showed decreased interstitial collagen accumulation and no changes in cellularity and apoptotic rate compared to controls. Age-related expression of vascular cell adhesion molecule-1 (VCAM-1)-positive microvessels was also reduced in PLC-treated rabbits. In vitro, the 16-hour, 10-microM PLC treatment reduced collagen type 1 and VCAM-1 transcripts, which were investigated by reverse transcription-polymerase chain reaction, more markedly in cardiac fibroblasts from aged donors. In the latter, the anti-VCAM-1 antibody treatment was found to be associated with a reduction in collagen type I transcripts. Our results demonstrated that long-term PLC treatment partially prevents age-related interstitial remodeling and suggests that a more complex interstitial cell-to-cell signaling regulates senescent myocardium properties.

Reactive oxygen species mediate a cellular 'memory' of high glucose stress signalling

AIMS/HYPOTHESIS

A long-term 'memory' of hyperglycaemic stress, even when glycaemia is normalised, has been previously reported in endothelial cells. In this report we sought to duplicate and extend this finding.

MATERIALS AND METHODS

HUVECs and ARPE-19 retinal cells were incubated in 5 or in 30 mmol/l glucose for 3 weeks or subjected to 1 week of normal glucose after being exposed for 2 weeks to continuous high glucose. HUVECs were also treated in this last condition with several antioxidants. Similarly, four groups of rats were studied for 3 weeks: (1) normal rats; (2) diabetic rats not treated with insulin; (3) diabetic rats treated with insulin during the last week; and (4) diabetic rats treated with insulin plus alpha-lipoic acid in the last week.

RESULTS

In human endothelial cells and ARPE-19 retinal cells in culture, as well as in the retina of diabetic rats, levels of the following markers of high glucose stress remained induced for 1 week after levels of glucose had normalised: protein kinase C-beta, NAD(P)H oxidase subunit p47phox, BCL-2-associated X protein, 3-nitrotyrosine, fibronectin, poly(ADP-ribose) Blockade of reactive species using different approaches, i.e. the mitochondrial antioxidant alpha-lipoic acid, overexpression of uncoupling protein 2, oxypurinol, apocynin and the poly(ADP-ribose) polymerase inhibitor PJ34, interrupted the induction both of high glucose stress markers and of the fluorescent reactive oxygen species (ROS) probe CM-H(2)DCFDA in human endothelial cells. Similar results were obtained in the retina of diabetic rats with alpha-lipoic acid added to the last week of normalised glucose.

CONCLUSIONS/INTERPRETATION

These results provide proof-of-principle of a ROS-mediated cellular persistence of vascular stress after glucose normalisation.

Genomic structure, alternative maturation and tissue expression of the human BBOX1 gene

Gamma-butyrobetaine hydroxylase (BBOX1) is the enzyme responsible for the biosynthesis of l-carnitine, a key molecule of fatty acid metabolism. This cytosolic dimeric protein belongs to the dioxygenase family. In human, enzyme activity has been detected in kidney, liver and brain. The human gene encoding gamma-butyrobetaine hydroxylase is located on chromosome 11. Although the protein structure and activity have been extensively described, little information is available concerning BBOX1 structure and expression. In this study, the organization of the human gene was determined. The structure and functions of the 5'- and 3'-untranslated regions of the human BBOX1 mRNA were characterized in kidney, liver and brain. Our experiments revealed that the transcription initiation of the human BBOX1 gene might occur at 3 different exons, and that the expression level of each type of transcript is organ-specific. We showed that the use of 3 different promoters is responsible for the 5'-end heterogeneity. Investigations on BBOX1 mRNA maturation highlighted an alternative polyadenylation mechanism that generates two 3'-untranslated regions differing by their length. This alternative polyadenylation exhibited a tissue specificity.

L-Carnitine and -Lipoic Acid Improve Age-Associated Decline in Mitochondrial Respiratory Chain Activity of Rat Heart Muscle

The aging process is characterized by a general decline in physiological functions that affects many tissues and increases the risk of death. In the present investigation using various substrates, the respiration rate was observed in young, middle-aged, and aged rats upon administration of carnitine (300 mg/kg body weight) and lipoic acid (100 mg/kg body weight). We observed that the rate of respiration, both State 3 and respiratory control ratio, decreased significantly in aged rats after using various substrates (except succinate). An increase in the State 4 respiration was observed in aged rats when beta-hydroxybutyrate as well as pyruvate and malate were used as substrates, whereas no change in the adenosine diphosphate/oxygen ratio ratio was observed. These changes were brought to normal levels upon cosupplementation of carnitine and lipoic acid. Thus, this study provides evidence for the role of carnitine and lipoic acid in alleviating the age-related decline in mitochondrial respiratory activity.

Suppression of N-nitrosodiethylamine induced hepatocarcinogenesis by silymarin in rats

Antioxidants are one of the key players in tumorigenesis, several natural and synthetic antioxidants were shown to have anticancer effects. In the present investigation the efficacy of silymarin on the antioxidant status of N-nitrosodiethylamine (NDEA) induced hepatocarcinogenesis in Wistar albino male rats were assessed. The animals were divided into five groups. The animals in the groups 1 and 3 were normal control and silymarin control, respectively. Groups 2, 4 and 5 were administered with 0.01% NDEA in drinking water for 15 weeks to induce hepatocellular carcinoma (HCC). Starting 1 week prior to NDEA administration group 4 animals were treated with silymarin in diet for 16 weeks, 10 weeks after NDEA administration group 5 animals were treated with silymarin and continued till the end of the experiment period (16 weeks). After the experimental period the body weight, relative liver weight, number of nodules, size of nodules, the levels of lipid peroxidation, glutathione (GSH), and the activities of antioxidant enzymes were assessed in both haemolysate and liver tissue. In group 2 hepatocellular carcinoma induced animals there was an increase in the number of nodules, relative liver weight. The levels of lipid peroxides were elevated with subsequent decrease in the body weight, (glutathione) GSH, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD). In contrast, silymarin + NDEA treated groups 4 and 5 animals showed a significant decrease in the number of nodules with concomitant decrease in the lipid peroxidation status. The levels of GSH and the activities of antioxidant enzymes in both haemolysate and liver were improved when compared with hepatocellular carcinoma induced group 2 animals. The electron microscopy studies were also carried out which supports the chemopreventive action of the silymarin against NDEA administration during liver cancer progression. These findings suggest that silymarin suppresses NDEA induced hepatocarcinogenesis by modulating the antioxidant defense status of the animals.

Carnitine and Lipoic Acid Alleviates Protein Oxidation in Heart Mitochondria During Aging Process

Oxidative modification alters the function of proteins and is thought to play an important role in the decline of cellular function during aging process. In the present study, we have evaluated the levels of oxidant production, protein oxidation, reduced and oxidized glutathione in young, middle aged and aged rats. The animals were divided into six groups, each group consisting of six animals each. Groups I and II were young rats, Groups III and IV were middle-aged rats and Groups V and VI were aged rats. Groups II, IV and VI were treated with carnitine (300 mg/kg bw) and Dl-alpha-Lipoic acid (100 mg/kg bw) for 28 days. Statistical significance was carried out using ANOVA. There was a significant reduction in the levels of reduced glutathione and Redox ratio (P<0.05) in aged rats whereas elevation in the levels of oxidant production, protein carbonyls, advanced oxidation protein products and oxidized glutathione were observed. Co-supplementation of carnitine and lipoic acid improved these levels to near normalcy. Thus we conclude that the utilization of carnitine and lipoic acid will lead to an improvement in the quality of living during the later stages of life by preventing free radical induced damage to the proteins.

Oxidative Stress and DNA Single Strand Breaks in Skeletal Muscle of Aged Rats: Role of Carnitine and Lipoicacid

The exposure of biological system to various conditions of oxidative stress is the major contributor for aging process. Oxidative stress in turn increases the cellular levels of oxidatively modified proteins, lipids and nucleic acids resulting in a loss of physical activity and metabolic integrity. In this study, we evaluated the role of L-carnitine and DL-alpha-lipoic acid in minimizing oxidant generation and macromolecular damage in skeletal muscle of aged rats. We found that the oxidant generation was increased in aged rat skeletal muscle when compared to young rats. There was a simultaneous increase in the levels of lipid peroxidation, protein carbonyl content and DNA strand breaks in aged rat skeletal muscle. Administration of L-carnitine (300 mg/kg body wt/day) and DL-alpha-lipoic acid (100 mg/kg body wt/day) to aged rats for 30 days, decreased the oxidant generation, lipid peroxidation, protein carbonylation and DNA strand breaks. We concluded that co-administration of carnitine and lipoic acid to aged rats has the potential to prevent oxidative stress mediated macromolecular damage in skeletal muscle of aged rats by their putative role as efficient antioxidants.

Vitamin E and L-carnitine, separately or in combination, in the prevention of radiation-induced oral mucositis and myelosuppression: a controlled study in a rat model

The aim of this study was to determine the effects of vitamin E (VE) and L-carnitine (LC) supplementation, separately or in combination, on radiation-induced oral mucositis and myelosuppression. Group 1 received no treatment (control). Group 2 received 15 Gray of 60Co gamma irradiation as a single dose to total cranium (IR). Group 3, 4, and 5 received irradiation plus 40 mg/kg/day VE (IR+VE) or 200 mg/kg/day LC (IR+LC) or in combination (IR+VE+LC) respectively. Clinically and histopathologically, assessments of mucosal reactions were performed by two independent experts in Radiation Oncology and Pathology, respectively. Hematologic analyses and antioxidant enzyme evaluations were also performed. Irradiation significantly increased oral mucositis, and decreased thrombocyte and White Blood Cell counts. A significant increase in malondialdehyde (MDA) levels and decrease in superoxide dismutase (SOD) and catalase (CAT) activities in plasma were found in the IR group. VE and LC administration, separately, plus irradiation significantly delayed the starting day, and reduced the severity of, oral mucositis. This administration also reduced a fall in the numbers of thrombocyte and WBC caused by irradiation, and decreased the MDA level, and increased the activity of SOD and CAT enzymes in the plasma. VE and LC, in combination, plus irradiation did not provide a superior radioprotection against radiation-induced toxicities.

Mitochondrial membrane damage during aging process in rat heart: potential efficacy of L-carnitine and DL alpha lipoic acid

Mitochondria are the main intracellular source of oxidizing free radicals and these oxidants produced exhibit selectivity in damaging mitochondrial macromolecules and membrane functions. In the present study we have investigated the effect of co-supplementation of carnitine (300 mg/kg bw) and lipoic acid (100 mg/kg bw) for 28 days in young, middle aged and aged rats and evaluated the effect of these compounds on age-related alterations in mitochondrial membrane functions. The levels of H2O2 were increased in both middle aged and aged rats with a concomitant decrease in the levels of cardiolipin and mitochondrial membrane potential. The levels of membrane bound ATPases were also decreased in aged rats along with alterations in mitochondrial morphology. Supplementation of carnitine and lipoic acid to middle aged and aged rats brought these changes to near normalcy. Thus, lipoic acid acts with carnitine to improve mitochondrial-supported bioenergetics and also improves general antioxidant status, thereby effectively attenuating any putative increase in oxidative stress with age.