Acetyl-L-carnitine and alpha-lipoic acid supplementation of aged beagle dogs improves learning in two landmark discrimination tests

Strategies to protect against age-related mitochondrial decay: Do natural products and their derivatives help?

Mitochondria serve vital roles critical for overall cellular function outside of energy transduction. Thus, mitochondrial decay is postulated to be a key factor in aging and in age-related diseases. Mitochondria may be targets of their own decay through oxidative damage. However, treating animals with antioxidants has been met with only limited success in rejuvenating mitochondrial function or in increasing lifespan. A host of nutritional strategies outside of using traditional antioxidants have been devised to promote mitochondrial function. Dietary compounds are under study that induce gene expression, enhance mitochondrial biogenesis, mitophagy, or replenish key metabolites that decline with age. Moreover, redox-active compounds may now be targeted to mitochondria which improve their effectiveness. Herein we review the evidence that representative dietary effectors modulate mitochondrial function by stimulating their renewal or reversing the age-related loss of key metabolites. While in vitro evidence continues to accumulate that many of these compounds benefit mitochondrial function and/or prevent their decay, the results using animal models and, in some instances human clinical trials, are more mixed and sometimes even contraindicated. Thus, further research on optimal dosage and age of intervention are warranted before recommending potential mitochondrial rejuvenating compounds for human use.

Alpha-Lipoic Acid as a Nutritive Supplement for Humans and Animals: An Overview of Its Use in Dog Food

Simple Summary

A review of human and animal studies involving alpha-lipoic acid supplementation was conducted to determine the utility of alpha-lipoic acid in dog food. The present literature shows that alpha-lipoic acid has utility as a nutritive additive at concentrations of 2.7–4.94 mg/kg body weight/day and improves antioxidant capacity in dogs.

Abstract

Alpha-lipoic acid (a-LA) is used as a nutritive additive in dog food. Therefore, we performed a systematic review of studies published to date in PubMed, Google Scholar, Cochrane Library and MedlinePlus involving alpha-lipoic acid supplementation, which included human clinical trials as well as animal studies, to evaluate its utility as a supplement in foods for healthy, adult dogs. While an upper limit of alpha-lipoic acid intake in humans has not been conclusively determined, the levels for oral intake of a-LA have been better defined in animals, and distinct differences based on species have been described. The maximum tolerated oral dose of a-LA in dogs has been reported as 126 mg/kg body weight and the LD₅₀ as 400 to 500 mg/kg body weight. The antioxidant, anti-inflammatory and neuro-protective benefits of alpha-lipoic acid in dogs were observed at concentrations much lower than the maximum tolerated dose or proposed LD₅₀. At concentrations of 2.7–4.94 mg/kg body weight/day, alpha-lipoic acid is well tolerated and posed no health risks to dogs while providing improved antioxidant capacity. This review thereby supports the utility of alpha-lipoic acid as an effective nutritive additive in dog food.

Age-related defects in short-term plasticity are reversed by acetyl-L-carnitine at the mouse calyx of Held

Hearing acuity and sound localization are affected by aging and may contribute to cognitive dementias. Although loss of sensorineural conduction is well documented to occur with age, little is known regarding short-term synaptic plasticity in central auditory nuclei. Age-related changes in synaptic transmission properties were evaluated at the mouse calyx of Held, a sign-inverting relay synapse in the circuit for sound localization, in juvenile adults (1 month old) and late middle-aged (18-21 months old) mice. Synaptic timing and short-term plasticity were severely disrupted in older mice. Surprisingly, acetyl-l-carnitine (ALCAR), an anti-inflammatory agent that facilitates mitochondrial function, fully reversed synaptic transmission delays and defects in short-term plasticity in aged mice to reflect transmission similar to that seen in juvenile adults. These findings support ALCAR supplementation as an adjuvant to improve short-term plasticity and potentially central nervous system performance in animals compromised by age and/or neurodegenerative disease.

Cognitive enhancement in old dogs from dietary supplementation with a nutrient blend containing arginine, antioxidants, B vitamins and fish oil

This study focused on the hypothesis that cognitive decline in aged dogs could be attenuated by dietary supplementation with a nutrient blend consisting of antioxidants, B vitamins, fish oil and l-arginine, referred to hereafter as the Brain Protection Blend (BPB). Baseline cognitive assessment before the start of treatment was used to establish cognitively equivalent control (10·464+2·33 kg) and treatment (12·118+3·386 kg) groups of aged dogs between 9·1 and 11·5 years of age and with body condition score of 5. After an initial wash-in period, all dogs were tested over a 6-month period on cognitive test protocols that assessed four phases of a landmark discrimination learning protocol, which assessed a spatial learning skill based on utilisation of external cues, and egocentric discrimination task, which assessed spatial learning based on internal body-centred cues. The BPB-supplemented group showed significantly better performance than the controls on the landmark 1 (P=0·0446) discrimination learning tasks, and on two egocentric discrimination reversal learning tasks (P=0·005 and P=0·01, respectively). The groups did not differ significantly (P>0·10) on the landmark zero discrimination task and the egocentric discrimination learning task. These results suggest beneficial effects are positively linked to task complexity. Many of the nutrients supplemented in the BPB diet were significantly higher in plasma, including arginine, α-tocopherol, DHA and EPA. These results indicate that long-term supplementation with the BPB can have cognition-improving effects and support the use of nutritional strategies in targeting brain ageing-associated risk factors as an intervention to delay cognitive ageing.

Alpha-synuclein, epigenetics, mitochondria, metabolism, calcium traffic, & circadian dysfunction in Parkinson's disease. An integrated strategy for management

The motor deficits which characterise the sporadic form of Parkinson's disease arise from age-related loss of a subset of dopamine neurons in the substantia nigra. Although motor symptoms respond to dopamine replacement therapies, the underlying disease process remains. This review details some features of the progressive molecular pathology and proposes deployment of a combination of nutrients: R-lipoic acid, acetyl-l-carnitine, ubiquinol, melatonin (or receptor agonists) and vitamin D3, with the collective potential to slow progression of these features. The main nutrient targets include impaired mitochondria and the associated oxidative/nitrosative stress, calcium stress and impaired gene transcription induced by pathogenic forms of alpha- synuclein. Benefits may be achieved via nutrient influence on epigenetic signaling pathways governing transcription factors for mitochondrial biogenesis, antioxidant defences and the autophagy-lysosomal pathway, via regulation of the metabolic energy sensor AMP activated protein kinase (AMPK) and the mammalian target of rapamycin mTOR. Nutrients also benefit expression of the transcription factor for neuronal survival (NR4A2), trophic factors GDNF and BDNF, and age-related calcium signals. In addition a number of non-motor related dysfunctions in circadian control, clock genes and associated metabolic, endocrine and sleep-wake activity are briefly addressed, as are late-stage complications in respect of cognitive decline and osteoporosis. Analysis of the network of nutrient effects reveals how beneficial synergies may counter the accumulation and promote clearance of pathogenic alpha-synuclein.

The oil-rich alga Schizochytrium sp. as a dietary source of docosahexaenoic acid improves shape discrimination learning associated with visual processing in a canine model of senescence

Whole cell Schizochytrium sp. is a rich source of omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) including docosahexaenoic acid (DHA), an important nutrient for brain health. Aged beagle dogs experienced on a visuospatial task of working memory, variable-delay delayed-non-matching-to-position were used to assess efficacy of DHA-rich microalgae based upon DHA wt% of total phospholipids and 8-iso-PGF_2α concentrations in plasma, and performance on cognitive assessments of visual object discrimination, learning, and memory consolidation after 25 weeks on fortified diet. Improved DHA status (p<0.001) and initial learning of the protocols for visual and variable contrast discrimination (p<0.05), but not long-term recall of the concurrent discrimination task were observed in animals fed the algal-fortified diet. Overall, results were consistent with dried Schizochytrium sp. as a source of n-3 LCPUFA nutrition to support DHA status in large mammals, and healthy brain function in a canine model of senescence.

Cats in Positive Energy Balance Have Lower Rates of Adipose Gain When Fed Diets Containing 188 versus 121 ppm L-Carnitine

L-carnitine (LC) is included in select adult feline diets for weight management. This study investigated whether feeding adult cats with diets containing either 188 ppm of LC (LC188) or 121 ppm of LC (LC121) and feeding them 120% of maintenance energy requirement (MER) resulted in differences in total energy expenditure (EE), metabolic fuel selection, BW, body composition, and behavior. Cats (n = 20, 4 ± 1.2 yrs) were stratified for BCS and randomly assigned to one of two dietary treatments and fed for 16 weeks. BW was measured weekly, and indirect calorimetry, body composition, physical activity, play motivation, and cognition were measured at baseline and throughout the study. A mixed, repeated measures, ANCOVA model was used. Cats in both treatments gained BW (P < 0.05) throughout the study, with no differences between treatments at any time point (P > 0.05). There were no differences in body composition between groups at baseline; however, body fat (g) and body fat : lean mass ratio were greater in cats fed LC121 in contrast to cats fed LC188 (P < 0.05) on week 16. No other outcomes differed between treatments (P > 0.05). Supplying dietary LC at a dose of at least 188 ppm may be beneficial for the health and well-being of cats fed above MER.

Nutrition for working and service dogs

Conformation, genetics, and behavioral drive are the major determinants of success in canine athletes, although controllable variables, such as training and nutrition, play an important role. The scope and breadth of canine athletic events has expanded dramatically in the past 30 years, but with limited research on performance nutrition. There are considerable data examining nutritional physiology in endurance dogs and in sprinting dogs; however, nutritional studies for agility, field trial, and detection are rare. This article highlights basic nutritional physiology and interventions for exercise, and reviews newer investigations regarding aging working and service dogs, and canine detection activities.

Neuronal failure in Alzheimer's disease: a view through the oxidative stress looking-glass

Considerable debate and controversy surround the cause(s) of Alzheimer's disease (AD). To date, several theories have gained notoriety, however none is universally accepted. In this review, we provide evidence for the oxidative stress-induced AD cascade that posits aged mitochondria as the critical origin of neurodegeneration in AD.

Mitochondrial cofactors in experimental Huntington's disease: behavioral, biochemical and histological evaluation

The present study was carried out to evaluate the beneficial effect of mitochondrial cofactors; alpha-lipoic acid (ALA) and acetyl-l-carnitine (ALCAR) in 3-nitropropionic acid (3-NP) induced experimental model of Huntington's disease (HD). HD was developed by administering sub-chronic doses of 3-NP, intraperitoneally, twice daily for 17 days. The animals were assessed for their behavioral performance in terms of motor (spontaneous locomotor activity, narrow beam walk test, footprint analysis and rotarod test) and cognitive (elevated plus maze and T-maze tests) functions. 3-NP treated animals showed impairment in motor coordination such as decreased stride length, increased distance between inner toes, and increased gait angle. Increased transfer latency on elevated plus maze and T-maze tasks revealed cognition deficits in 3-NP treated animals. Increased lipid peroxidation and concomitant decrease in thiol levels were also observed. 3-NP administration also induced histopathological changes in terms of enhanced striatal lesion volume, presence of pyknotic nuclei and astrogliosis. However, combined supplementation with ALA+ALCAR to 3-NP administered animals for 21 days was able to efficiently improve behavioral deficits, attenuate oxidative stress and histological changes, suggesting a putative role of these two supplements if given together in ameliorating 3-NP induced impairments and thus could be engaged in managing HD.

Effects of alpha-lipoic acid on associative and spatial memory of sham-irradiated and 56Fe-irradiated C57BL/6J male mice

Cranial irradiation with (56)Fe, a form of space radiation, causes hippocampus-dependent cognitive changes. (56)Fe irradiation also increases reactive oxygen species (ROS) levels, which may contribute to these changes. Therefore, we investigated the effects of the antioxidant alpha lipoic acid (ALA) on cognition following sham-irradiation and irradiation. Male mice were irradiated (brain only) with (56)Fe (3 Gy) or sham-irradiated at 6-9 months of age. Half of the mice remained fed a regular chow and the other half of the mice were fed a caloric-matched diet containing ALA starting two-weeks prior to irradiation and throughout cognitive testing. Following cognitive testing, levels of 3-nitrotyrosine (3NT), a marker of oxidative protein stress, and levels of microtubule-associated protein (MAP-2), a dendritic protein important for cognition, were assessed using immunohistochemistry and confocal microscopy. ALA prevented radiation-induced impairments in spatial memory retention in the hippocampal and cortical dependent water maze probe trials following reversal learning. However, in sham-irradiated mice, ALA treatment impaired cortical-dependent novel object recognition and amygdala-dependent cued fear conditioning. There was a trend towards lower 3NT levels in irradiated mice receiving a diet containing ALA than irradiated mice receiving a regular diet. In the hippocampal dentate gyrus of mice on regular diet, irradiated mice had higher levels of MAP-2 immunoreactivity than sham-irradiated mice. Thus, ALA might have differential effects on the brain under normal physiological conditions and those involving environmental challenges such as cranial irradiation.

Frontiers in Alzheimer's disease therapeutics

Alzheimer disease (AD) is a progressive neurodegenerative disease which begins with insidious deterioration of higher cognition and progresses to severe dementia. Clinical symptoms typically involve impairment of memory and at least one other cognitive domain. Because of the exponential increase in the incidence of AD with age, the aging population across the world has seen a congruous increase AD, emphasizing the importance of disease altering therapy. Current therapeutics on the market, including cholinesterase inhibitors and N-methyl-D-aspartate receptor antagonists, provide symptomatic relief but do not alter progression of the disease. Therefore, progress in the areas of prevention and disease modification may be of critical interest. In this review, we summarize novel AD therapeutics that are currently being explored, and also mechanisms of action of specific drugs within the context of current knowledge of AD pathologic pathways.

Reactive oxygen species in the regulation of synaptic plasticity and memory

The brain is a metabolically active organ exhibiting high oxygen consumption and robust production of reactive oxygen species (ROS). The large amounts of ROS are kept in check by an elaborate network of antioxidants, which sometimes fail and lead to neuronal oxidative stress. Thus, ROS are typically categorized as neurotoxic molecules and typically exert their detrimental effects via oxidation of essential macromolecules such as enzymes and cytoskeletal proteins. Most importantly, excessive ROS are associated with decreased performance in cognitive function. However, at physiological concentrations, ROS are involved in functional changes necessary for synaptic plasticity and hence, for normal cognitive function. The fine line of role reversal of ROS from good molecules to bad molecules is far from being fully understood. This review focuses on identifying the multiple sources of ROS in the mammalian nervous system and on presenting evidence for the critical and essential role of ROS in synaptic plasticity and memory. The review also shows that the inability to restrain either age- or pathology-related increases in ROS levels leads to opposite, detrimental effects that are involved in impairments in synaptic plasticity and memory function.

Evidence that α-lipoic acid inhibits NF-κB activation independent of its antioxidant function

OBJECTIVE

α-Lipoic acid (LA) exerts beneficial effects in cardiovascular diseases though its antioxidant and/or anti-inflammatory functions. It is postulated that the anti-inflammatory function of LA results from its antioxidant function. In this study we tested whether inhibition of NF-κB by LA is dependent on its antioxidant function.

METHODS

Human umbilical vein endothelial cells (HUVECs) were treated with tumor necrosis factor-α (TNFα) in the presence of various antioxidants, including LA, tiron, apocynin, and tempol. The activation of the nuclear factor-κB (NF-κB) signaling pathway was then analyzed.

RESULTS

LA, but not other tested antioxidants, inhibited TNFα-induced inhibitor-kappaB-α (IκBα) degradation and VCAM-1 and COX2 expression in HUVECs. Although LA activated the phosphatidylinositol-3-kinase (PI3-kinase)/Akt pathway in HUVECs, inhibition of Akt by LY294002 did not affect inhibition of TNFα-induced IκBα degradation by LA. In transient co-transfection assays of a constitutively active mutant of IκB kinase-2 (IKK2), IKK2(EE), and a NF-κB luciferase reporter construct, LA dose-dependently inhibited IKK2(EE)-induced NF-κB activation in addition to inhibiting IKK activity in in vitro assays. Consistent with the effect on luciferase expression, LA inhibited IKK2(EE)-induced cyclo-oxygenase-2 (COX2) expression, suggesting that IKK2 inhibition by LA may be a relevant mechanism that explains its anti-inflammatory effects.

CONCLUSIONS

LA inhibits NF-κB activation through antioxidant-independent and probably IKK-dependent mechanisms.

Age-related oxidative decline of mitochondrial functions in rat brain is prevented by long term oral antioxidant supplementation

A combination of antioxidants (N-acetyl cysteine, α-lipoic acid, and α-tocopherol) was selected for long term oral supplementation study in rats for protective effects on age-related mitochondrial alterations in the brain. Four groups of rats were chosen: young control (6-7 months); aged rats (22-24 months); aged rats (22-24 months) on daily antioxidant supplementation from 18 month onwards and young rats (6-7 months) on daily antioxidant supplementation from 2 month onwards. The brain mitochondrial functional parameters, status of antioxidant enzymes and accumulation of oxidative damage markers were measured in the four groups of rats. A significant decrease in complex IV activity and a loss of transmembrane potential and phosphorylation capacity along with an increased accumulation of oxidative damage markers and compromised antioxidant enzyme status were noticed in aged rat brain mitochondria as compared to that in young controls, but in aged rats supplemented with oral antioxidants the mitochondrial alterations were largely prevented. Antioxidant supplementation in young rats had no effect on mitochondrial parameters investigated in this study. The results have implications in biochemical and functional deficits of brain during aging as well as in neurodegenerative disorders.

Lessons learnt from animal models: pathophysiology of neuropathic lysosomal storage disorders

Approximately 50 inborn errors of metabolism known as lysosomal storage disorders have been discovered to date, most of which are due to a single mutation in a gene encoding a soluble lysosomal enzyme. Consequently, inadequate enzyme activity results in the accumulation of substrates for that enzyme, invariably accompanied by a wide variety of secondary pathological changes. Many of these conditions remain untreatable, and therefore, research into pathogenic processes and potential treatment strategies is intense. A key tool for researchers in this area is the availability of clinically relevant animal models in which to study disease manifestation and evaluate therapeutic outcomes. Large numbers of both naturally occurring and genetically modified animal models of neurodegenerative lysosomal storage disorders are in existence, with spontaneous models occurring in both large domestic (e.g., cat, dog, sheep) and small (e.g., mouse) animal species. Many have undergone rigorous phenotypic characterization and are now providing us with insights into neurological disease processes. The purpose of this review is to highlight some of the major lessons learnt from these studies.

Mitochondrial dynamics in Alzheimer's disease: opportunities for future treatment strategies

The complexities that underlie the cognitive impairment and neurodegeneration characteristic of Alzheimer's disease (AD) have yet to be completely understood, although many factors in disease pathogenesis have been identified. Particularly important in disease development seem to be mitochondrial disturbances. As pivotal role players in cellular metabolism, mitochondria are pertinent to cell survival and thus any deviation from their operation is certainly fatal. In this review, we describe how the dynamic balance of mitochondrial fission and fusion in particular is a necessary aspect of cell proliferation and that, as the cell ages, such balance is inevitably compromised to yield a destructive environment in which the cell cannot exist. Evidence for such disturbance is abundant in AD. Specifically, the dynamic balance of fission and fusion in AD is greatly shifted toward fission, and, as a result, affected neurons contain abnormal mitochondria that are unable to meet the metabolic demands of the cell. Moreover, mitochondrial distribution in AD cells is perinuclear, with few metabolic organelles in the distal processes, where they are normally distributed in healthy cells and are needed for exocytosis, ion channel pumps, synaptic function and other activities. AD neurons are thus characterized by increases in reactive oxidative species and decreases in metabolic capability, and, notably, these changes are evident very early in AD progression. We therefore believe that oxidative stress and altered mitochondrial dynamics contribute to the precipitation of AD pathology and thus cognitive decline. These implications provide a window for therapeutic intervention (i.e. mitochondrial protection) that has the potential to significantly deter AD progression if adequately developed. Current treatment strategies under investigation are described in this review.

Optimal micronutrients delay mitochondrial decay and age-associated diseases

Three of our research efforts are reviewed, which suggest that optimizing metabolism will delay aging and the diseases of aging in humans. (1) Research on delay of the mitochondrial decay of aging by supplementing rats with lipoic acid and acetyl carnitine. (2) The triage theory, which posits that modest micronutrient deficiencies (common in much of the population) accelerate molecular aging, including mitochondrial decay, and supportive evidence, including an analysis in depth of vitamin K, that suggests the importance of achieving optimal micronutrient intake for longevity. (3) The finding that decreased enzyme binding constants (increased Km) for coenzymes (or substrates) can result from protein deformation and loss of function due to loss of membrane fluidity with age, or to polymorphisms or mutation. The loss of enzyme function can be ameliorated by high doses of a B vitamin, which raises coenzyme levels, and indicates the importance of understanding the effects of age, or polymorphisms, on micronutrient requirements.

Oxidative stress in Alzheimer disease: a possibility for prevention

Oxidative stress is at the forefront of Alzheimer disease (AD) research. While its implications in the characteristic neurodegeneration of AD are vast, the most important aspect is that it seems increasingly apparent that oxidative stress is in fact a primary progenitor of the disease, and not merely an epiphenomenon. Moreover, evidence indicates that a long "dormant period" of gradual oxidative damage accumulation precedes and actually leads to the seemingly sudden appearance of clinical and pathological AD symptoms, including amyloid-beta deposition, neurofibrillary tangle formation, metabolic dysfunction, and cognitive decline. These findings provide important insights into the development of potential treatment regimens and even allude to the possibility of a preventative cure. In this review, we elaborate on the dynamic role of oxidative stress in AD and present corresponding treatment strategies that are currently under investigation.

Dietary supplementation with medium-chain TAG has long-lasting cognition-enhancing effects in aged dogs

The present study focused on the hypothesis that dietary supplementation with medium-chain TAG (MCT) will improve cognitive function in aged dogs by providing the brain with energy in the form of ketones. Aged Beagle dogs were subjected to a baseline battery of cognitive tests, which were used to establish cognitively equivalent control or treatment groups. The dogs in the treatment group were maintained on a diet supplemented with 5.5 % MCT. After an initial wash-in period, all the dogs were tested with a battery of cognitive test protocols, which assessed sequentially landmark discrimination learning ability, egocentric visuospatial function and attention. The groups were maintained on the diets for 8 months. The MCT-supplemented group showed significantly better performance in most of the test protocols than the control group. The group differences also varied as a function of task difficulty, with the more difficult task showing greater supplementation effects than the easier tasks. The group given the MCT supplement showed significantly elevated levels of beta-hydroxybutyrate, a ketone body. These results indicate, first, that long-term supplementation with MCT can have cognition-improving effects, and second, that MCT supplementation increases circulating levels of ketones. The results support the hypothesis that brain function of aged dogs can be improved by MCT supplementation, which provides the brain with an alternative energy source.

Oxidative Stress Induced Mitochondrial Failure and Vascular Hypoperfusion as a Key Initiator for the Development of Alzheimer Disease

Mitochondrial dysfunction may be a principal underlying event in aging, including age-associated brain degeneration. Mitochondria provide energy for basic metabolic processes. Their decay with age impairs cellular metabolism and leads to a decline of cellular function. Alzheimer disease (AD) and cerebrovascular accidents (CVAs) are two leading causes of age-related dementia. Increasing evidence strongly supports the theory that oxidative stress, largely due to reactive oxygen species (ROS), induces mitochondrial damage, which arises from chronic hypoperfusion and is primarily responsible for the pathogenesis that underlies both disease processes. Mitochondrial membrane potential, respiratory control ratios and cellular oxygen consumption decline with age and correlate with increased oxidant production. The sustained hypoperfusion and oxidative stress in brain tissues can stimulate the expression of nitric oxide synthases (NOSs) and brain endothelium probably increase the accumulation of oxidative stress products, which therefore contributes to blood brain barrier (BBB) breakdown and brain parenchymal cell damage. Determining the mechanisms behind these imbalances may provide crucial information in the development of new, more effective therapies for stroke and AD patients in the near future.

Alpha-lipoic acid induces elevated S-adenosylhomocysteine and depletes S-adenosylmethionine

Lipoic acid is a disulfhydryl-containing compound used in clinical medicine and in experimental models as an antioxidant. We developed a stable isotope dilution capillary gas chromatography/mass spectrometry assay for lipoic acid. We assayed a panel of the metabolites of transmethylation and transsulfuration 30 min after injecting 100 mg/kg lipoic acid in a rat model. Lipoic acid values rose 1000-fold in serum and 10-fold in liver. A methylated metabolite of lipoic acid was also detected but not quantitated. Lipoic acid injection caused a massive increase in serum S-adenosylhomocysteine and marked depletion of liver S-adenosylmethionine. Serum total cysteine was depleted but liver cysteine and glutathione were maintained. Serum total homocysteine doubled, with increases also in cystathionine, N,N-dimethylglycine, and alpha-aminobutyric acid. In contrast, after injection of 2-mercaptoethane sulfonic acid, serum total cysteine and homocysteine were markedly depleted and there were no effects on serum S-adenosylmethionine or S-adenosylhomocysteine. We conclude that large doses of lipoic acid displace sulfhydryls from binding sites, resulting in depletion of serum cysteine, but also pose a methylation burden with severe depletion of liver S-adenosylmethionine and massive release of S-adenosylhomocysteine. These changes may have previously unrecognized deleterious effects that should be investigated in both human disease and experimental models.

Short-term supplementation with acetyl-L-carnitine and lipoic acid alters plasma protein carbonyl levels but does not improve cognition in aged beagles

Previous work has shown that a diet enriched with antioxidants and mitochondrial co-factors improves cognition in aged dogs, which is accompanied by a reduction in oxidative damage in the brain. The objective of the present study was to assess the effects of supplementation with mitochondrial co-factors on cognition and plasma protein carbonyl levels in aged dogs. Specifically, we aimed to test whether the individual or combined action of lipoic acid (LA) and acetyl-l-carnitine (ALCAR) could account for the beneficial effects of the enriched diet that contained both plus antioxidants. Dogs were given LA or ALCAR, alone and then in combination and cognition was assessed using a spatial learning task and two discrimination and reversal paradigms. Dogs receiving the ALCAR supplement showed an increase in protein carbonyl levels that was associated with increased error scores on the spatial task, and which was reduced upon additional supplementation with LA. We did not observe significant positive effects on cognition. The present findings suggest that short-term supplementation with LA and ALCAR is insufficient to improve cognition in aged dogs, and that the beneficial effects of the full spectrum diet arose from either the cellular antioxidants alone or their interaction with LA and ALCAR.

Vitagenes, cellular stress response, and acetylcarnitine: relevance to hormesis

Modulation of endogenous cellular defense mechanisms via the stress response signaling represents an innovative approach to therapeutic intervention in diseases causing chronic damage, such as neurodegeneration and cancer. Protein thiols play a key role in redox sensing, and regulation of cellular redox state is crucial mediator of multiple metabolic, signaling, and transcriptional processes. Maintenance of optimal long-term health conditions is accomplished by a complex network of longevity assurance processes that are controlled by vitagenes, a group of genes involved in preserving cellular homeostasis during stressful conditions. Vitagenes encode for heat shock proteins (Hsp) Hsp32, Hsp70, the thioredoxin, and the sirtuin protein systems. Dietary antioxidants, such as polyphenols and L-carnitine/acetyl-L-carnitine, have recently been demonstrated to be neuroprotective through the activation of hormetic pathways, including vitagenes. The hormetic dose-response, challenges long-standing beliefs about the nature of the dose-response in a low dose zone, having the potential to affect significantly the design of pre-clinical studies and clinical trials as well as strategies for optimal patient dosing in the treatment of numerous diseases. Given the broad cytoprotective properties of the heat shock response, there is now strong interest in discovering and developing pharmacological agents capable of inducing these responses. In this review we discuss the most current and up-to-date understanding of the possible signaling mechanisms by which acetylcarnitine by activating vitagenes can differentially modulate signal transduction cascades inducing apoptosis/cell death in abnormal cancer cells but at the same time enhancing defensive enzymes to protect against carcinogenesis and neurodegeneration in normal cells. (c) 2009 International Union of Biochemistry and Molecular Biology, Inc.

Nutritional therapies to improve health: lessons from companion animals: Conference on ‘Multidisciplinary approaches to nutritional problems’ Symposium on ‘Nutrition and health’

Companion animals represent an under-utilised resource. The present paper is designed to encourage collaborative studies. Dogs and cats are out-bred animals that are willing to consume a consistent diet for long periods, so are ideal candidates for prospective studies of naturally-occurring disease. In some studies the effect of diet on survival has been substantial. Food restriction, for example, slows the development of osteoarthritis and increases the lifespan of Labrador retrievers by 2 years, protein and P restriction more than doubles the median survival time of dogs and cats with chronic kidney disease and addingn-3 fats and arginine to the diet of dogs with stage 3 lymphoma improves median survival time by one-quarter. Obesity is also very common in both dogs and cats and is also associated with disease as in human subjects. When interpreting these results, however, it is essential to take into account pathophysiological differences among species. Dogs and cats do not display all the characteristics of metabolic disease in human subjects, they metabolise fat well and atherosclerosis and cardiac infarction are uncommon. Such differences should not, however, preclude further study because differences among species often clarify knowledge. Monitoring of disease in companion animals may also provide a surveillance system for the safety of the food supply, as illustrated by recent outbreaks of acute renal failure and liver failure in cats and dogs in the USA caused respectively by melamine and mycotoxin contamination of pet foods.

Mitochondrial decay in the brains of old rats: ameliorating effect of alpha-lipoic acid and acetyl-L-carnitine

To investigate the mitochondrial decay and oxidative damage resulting from aging, the activities/kinetics of the mitochondrial complexes were examined in the brains of young and old rats as well as in old rats fed R-alpha-lipoic acid plus acetyl-L-carnitine (LA/ALC). The brain mitochondria of old rats, compared with young rats, had significantly decreased endogenous antioxidants and superoxide dismutase activity; more oxidative damage to lipids and proteins; and decreased activities of complex I, IV and V. Complex I showed a decrease in binding affinity (increase in K(m)) for substrates. Feeding LA/ALC to old rats partially restored age-associated mitochondrial dysfunction to the levels of the young rats. These results indicate that oxidative mitochondrial decay plays an important role in brain aging and that a combination of nutrients targeting mitochondria, such as LA/ALC, could ameliorate mitochondrial decay through preventing mitochondrial oxidative damage.

Cellular stress response: a novel target for chemoprevention and nutritional neuroprotection in aging, neurodegenerative disorders and longevity

The predominant molecular symptom of aging is the accumulation of altered gene products. Moreover, several conditions including protein, lipid or glucose oxidation disrupt redox homeostasis and lead to accumulation of unfolded or misfolded proteins in the aging brain. Alzheimer's and Parkinson's diseases or Friedreich ataxia are neurological diseases sharing, as a common denominator, production of abnormal proteins, mitochondrial dysfunction and oxidative stress, which contribute to the pathogenesis of these so called "protein conformational diseases". The central nervous system has evolved the conserved mechanism of unfolded protein response to cope with the accumulation of misfolded proteins. As one of the main intracellular redox systems involved in neuroprotection, the vitagene system is emerging as a neurohormetic potential target for novel cytoprotective interventions. Vitagenes encode for cytoprotective heat shock proteins (Hsp) Hsp70 and heme oxygenase-1, as well as thioredoxin reductase and sirtuins. Nutritional studies show that ageing in animals can be significantly influenced by dietary restriction. Thus, the impact of dietary factors on health and longevity is an increasingly appreciated area of research. Reducing energy intake by controlled caloric restriction or intermittent fasting increases lifespan and protects various tissues against disease. Genetics has revealed that ageing may be controlled by changes in intracellular NAD/NADH ratio regulating sirtuin, a group of proteins linked to aging, metabolism and stress tolerance in several organisms. Recent findings suggest that several phytochemicals exhibit biphasic dose responses on cells with low doses activating signaling pathways that result in increased expression of vitagenes encoding survival proteins, as in the case of the Keap1/Nrf2/ARE pathway activated by curcumin and NAD/NADH-sirtuin-1 activated by resveratrol. Consistently, the neuroprotective roles of dietary antioxidants including curcumin, acetyl-L-carnitine and carnosine have been demonstrated through the activation of these redox-sensitive intracellular pathways. Although the notion that stress proteins are neuroprotective is broadly accepted, still much work needs to be done in order to associate neuroprotection with specific pattern of stress responses. In this review the importance of vitagenes in the cellular stress response and the potential use of dietary antioxidants in the prevention and treatment of neurodegenerative disorders is discussed.

Mitochondrial nutrients improve immune dysfunction in the type 2 diabetic Goto-Kakizaki rats

The development of type 2 diabetes is accompanied by decreased immune function and the mechanisms are unclear. We hypothesize that oxidative damage and mitochondrial dysfunction may play an important role in the immune dysfunction in diabetes. In the present study, we investigated this hypothesis in diabetic Goto-Kakizaki rats by treatment with a combination of four mitochondrial-targeting nutrients, namely, R-α-lipoic acid, acetyl-L-carnitine, nicotinamide and biotin. We first studied the effects of the combination of these four nutrients on immune function by examining cell proliferation in immune organs (spleen and thymus) and immunomodulating factors in the plasma. We then examined, in the plasma and thymus, oxidative damage biomarkers, including lipid peroxidation, protein oxidation, reactive oxygen species, calcium and antioxidant defence systems, mitochondrial potential and apoptosis-inducing factors (caspase 3, p53 and p21). We found that immune dysfunction in these animals is associated with increased oxidative damage and mitochondrial dysfunction and that the nutrient treatment effectively elevated immune function, decreased oxidative damage, enhanced mitochondrial function and inhibited the elevation of apoptosis factors. These effects are comparable to, or greater than, those of the anti-diabetic drug pioglitazone. These data suggest that a rational combination of mitochondrial-targeting nutrients may be effective in improving immune function in type 2 diabetes through enhancement of mitochondrial function, decreased oxidative damage, and delayed cell death in the immune organs and blood.