Role of acetyl-L-carnitine in rat brain lipogenesis: implications for polyunsaturated fatty acid biosynthesis

Rational analysis of data from LC-MS/MS: new insights in acylcarnitines as biomarkers for brain disorders or neurotoxicity

Objective

LC-MS/MS-based metabolomics is an important tool for studying disease-related biomarkers. Conventionally, different strategies have been used to screen biomarkers. However, many studies for biomarker screening by different strategies have ignored the dose-response relationship between the biomarker level and exposure level, and no relevant studies have described and compared different strategies in detail. Phenobarbital (PHB) which belongs to the barbiturates, was selected as the typical representative of neurotoxins. Acylcarnitines have been promising candidates for diagnostic biomarkers for several neurological disorders and neurotoxicity. In this work, we aimed to use an acute PHB poisoning animal model to clarify PHB poisoning effects on plasma and brain acylcarnitine changes and how to rationally analyze data from LC-MS/MS.

Methods

The acylcarnitine profiles in plasma and brain regions in an actuate PHB poisoning animal model were utilized. The dose-response relationship between plasma PHB and carnitine and acylcarnitines (CARs) in plasma and brain were assessed by the variance analysis trend test and Spearman's rank correlation test. In different strategies, principal component analysis (PCA) and partial least squares discriminant analysis (OPLS-DA) screened the differential CARs, variable importance plots (VIPs) were utilized to select putative biomarkers for PHB-induced toxicity, and receiver operating characteristic (ROC) curve analysis then illustrated the reliability of biomarkers.

Results

Under the first strategy, 14 potential toxicity biomarkers were obtained including eight downregulated CARs with AUC >0.8. Under the second strategy, 11 potential toxicity biomarkers were obtained containing five downregulated CARs with AUC >0.8. Only when the dose-response relationship was fully considered, different strategies screen for the same biomarkers (plasma acetyl-carnitine (C2) and plasma decanoyl-carnitine (C10)), which indicated plasma acylcarnitines might serve as toxicity biomarkers. In addition, the plasma CAR level changes showed differences from brain CAR level changes, and correlations between plasma CARs and their brain counterparts were weak.

Conclusion

We found that plasma C2 and C10 might serve as toxicity biomarkers for PHB poisoning disorders, and PHB poisoning effects on changes in plasma CARs may not be fully representative of changes in brain CARs.

Comparing Brain and Blood Lipidome Changes following Single and Repetitive Mild Traumatic Brain Injury in Rats

Traumatic brain injury (TBI) is a major health concern in the United States and globally, contributing to disability and long-term neurological problems. Lipid dysregulation after TBI is underexplored, and a better understanding of lipid turnover and degradation could point to novel biomarker candidates and therapeutic targets. Here, we investigated overlapping lipidome changes in the brain and blood using a data-driven discovery approach to understand lipid alterations in the brain and serum compartments acutely following mild TBI (mTBI) and the potential efflux of brain lipids to peripheral blood. The cortices and sera from male and female Sprague-Dawley rats were analyzed via ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS) in both positive and negative ion modes following single and repetitive closed head impacts. The overlapping lipids in the data sets were identified with an in-house data dictionary for investigating lipid class changes. MS-based lipid profiling revealed overall increased changes in the serum compartment, while the brain lipids primarily showed decreased changes. Interestingly, there were prominent alterations in the sphingolipid class in the brain and blood compartments after single and repetitive injury, which may suggest efflux of brain sphingolipids into the blood after TBI. Genetic algorithms were used for predictive panel selection to classify injured and control samples with high sensitivity and specificity. These overlapping lipid panels primarily mapped to the glycerophospholipid metabolism pathway with Benjamini-Hochberg adjusted q-values less than 0.05. Collectively, these results detail overlapping lipidome changes following mTBI in the brain and blood compartments, increasing our understanding of TBI-related lipid dysregulation while identifying novel biomarker candidates.

Conceptual foundations of acetylcarnitine supplementation in neuropsychiatric long COVID syndrome: a narrative review

Post-acute sequelae of COVID-19 can present as multi-organ pathology, with neuropsychiatric symptoms being the most common symptom complex, characterizing long COVID as a syndrome with a significant disease burden for affected individuals. Several typical symptoms of long COVID, such as fatigue, depressive symptoms and cognitive impairment, are also key features of other psychiatric disorders such as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and major depressive disorder (MDD). However, clinically successful treatment strategies are still lacking and are often inspired by treatment options for diseases with similar clinical presentations, such as ME/CFS. Acetylcarnitine, the shortest metabolite of a class of fatty acid metabolites called acylcarnitines and one of the most abundant blood metabolites in humans can be used as a dietary/nutritional supplement with proven clinical efficacy in the treatment of MDD, ME/CFS and other neuropsychiatric disorders. Basic research in recent decades has established acylcarnitines in general, and acetylcarnitine in particular, as important regulators and indicators of mitochondrial function and other physiological processes such as neuroinflammation and energy production pathways. In this review, we will compare the clinical basis of neuropsychiatric long COVID with other fatigue-associated diseases. We will also review common molecular disease mechanisms associated with altered acetylcarnitine metabolism and the potential of acetylcarnitine to interfere with these as a therapeutic agent. Finally, we will review the current evidence for acetylcarnitine as a supplement in the treatment of fatigue-associated diseases and propose future research strategies to investigate the potential of acetylcarnitine as a treatment option for long COVID.

Identifying Hair Biomarker Candidates for Alzheimer's Disease Using Three High Resolution Mass Spectrometry-Based Untargeted Metabolomics Strategies

High-resolution mass spectrometry (HRMS)-based untargeted metabolomics strategies have emerged as an effective tool for discovering biomarkers of Alzheimer's disease (AD). There are various HRMS-based untargeted metabolomics strategies for biomarker discovery, including the data-dependent acquisition (DDA) method, the combination of full scan and target MS/MS, and the all ion fragmentation (AIF) method. Hair has emerged as a potential biospecimen for biomarker discovery in clinical research since it might reflect the circulating metabolic profiles over several months, while the analytical performances of the different data acquisition methods for hair biomarker discovery have been rarely investigated. Here, the analytical performances of three data acquisition methods in HRMS-based untargeted metabolomics for hair biomarker discovery were evaluated. The human hair samples from AD patients (N = 23) and cognitively normal individuals (N = 23) were used as an example. The most significant number of discriminatory features was acquired using the full scan (407), which is approximately 10-fold higher than that using the DDA strategy (41) and 11% higher than that using the AIF strategy (366). Only 66% of discriminatory chemicals discovered in the DDA strategy were discriminatory features in the full scan dataset. Moreover, compared to the deconvoluted MS/MS spectra with coeluted and background ions from the AIF method, the MS/MS spectrum obtained from the targeted MS/MS approach is cleaner and purer. Therefore, an untargeted metabolomics strategy combining the full scan with the targeted MS/MS method could obtain most discriminatory features along with a high quality MS/MS spectrum for discovering the AD biomarkers.

[Possibilities of sequential levocarnitin and acetylcarnitin treatment in correcting cognitive deficiency in patients with cardiovascular diseases]

OBJECTIVE

To evaluate the effectiveness of sequential therapy with levocarnitine and acetylcarnitine in patients with cardiovascular pathology (arterial hypertension and/or coronary heart disease) and moderate cognitive deficits.

MATERIAL AND METHODS

The study included 120 patients aged 54-67 years. The main group of patients (n=60) in addition to the basic treatment of the underlying disease received l-carnitine (Elkar solution for intravenous and intramuscular injection of 100 mg/ml, the company «PIK-FARMA»)/jet during 10 days in a dose of 1000 mg/day, with following transition to oral administration of acetyl-l-carnitine (Carnitin, the company «PIK-FARMA»), 500 mg (2 cap Sula) 2 times a day for 2 months. The comparison group (n=60) received basic therapy for major diseases. The total duration of follow-up was 70 days.

RESULTS

The results obtained indicate that in such comorbid patients, the use of levocarnitine and acetylcarnitine reduces the severity of cognitive deficits. An important aspect of their pathogenetic effect on the severity of cognitive deficits may be the possibility of correcting endothelial dysfunction. The use of levocarnitine and acetylcarnitine in patients with cardiovascular pathology has demonstrated good tolerability and safety.

L-Carnitine and Acetyl-L-carnitine Roles and Neuroprotection in Developing Brain

L-Carnitine functions to transport long chain fatty acyl-CoAs into the mitochondria for degradation by β-oxidation. Treatment with L-carnitine can ameliorate metabolic imbalances in many inborn errors of metabolism. In recent years there has been considerable interest in the therapeutic potential of L-carnitine and its acetylated derivative acetyl-L-carnitine (ALCAR) for neuroprotection in a number of disorders including hypoxia-ischemia, traumatic brain injury, Alzheimer's disease and in conditions leading to central or peripheral nervous system injury. There is compelling evidence from preclinical studies that L-carnitine and ALCAR can improve energy status, decrease oxidative stress and prevent subsequent cell death in models of adult, neonatal and pediatric brain injury. ALCAR can provide an acetyl moiety that can be oxidized for energy, used as a precursor for acetylcholine, or incorporated into glutamate, glutamine and GABA, or into lipids for myelination and cell growth. Administration of ALCAR after brain injury in rat pups improved long-term functional outcomes, including memory. Additional studies are needed to better explore the potential of L-carnitine and ALCAR for protection of developing brain as there is an urgent need for therapies that can improve outcome after neonatal and pediatric brain injury.

Global Metabolomic Profiling of Mice Brains following Experimental Infection with the Cyst-Forming Toxoplasma gondii

The interplay between the Apicomplexan parasite Toxoplasma gondii and its host has been largely studied. However, molecular changes at the metabolic level in the host central nervous system and pathogenesis-associated metabolites during brain infection are largely unexplored. We used a global metabolomics strategy to identify differentially regulated metabolites and affected metabolic pathways in BALB/c mice during infection with T. gondii Pru strain at 7, 14 and 21 days post-infection (DPI). The non-targeted Liquid Chromatography-Mass Spectrometry (LC-MS) metabolomics analysis detected approximately 2,755 retention time-exact mass pairs, of which more than 60 had significantly differential profiles at different stages of infection. These include amino acids, organic acids, carbohydrates, fatty acids, and vitamins. The biological significance of these metabolites is discussed. Principal Component Analysis and Orthogonal Partial Least Square-Discriminant Analysis showed the metabolites' profile to change over time with the most significant changes occurring at 14 DPI. Correlated metabolic pathway imbalances were observed in carbohydrate metabolism, lipid metabolism, energetic metabolism and fatty acid oxidation. Eight metabolites correlated with the physical recovery from infection-caused illness were identified. These findings indicate that global metabolomics adopted in this study is a sensitive approach for detecting metabolic alterations in T. gondii-infected mice and generated a comparative metabolic profile of brain tissue distinguishing infected from non-infected host.

L-Acetylcarnitine in dysthymic disorder in elderly patients: a double-blind, multicenter, controlled randomized study vs. fluoxetine

INTRODUCTION

L-Acetylcarnitine (LAC), the acetyl ester of carnitine naturally present in the central nervous system and involved in several neural pathways, has been demonstrated to be active in various animal experimental models resembling some features of human depression. The aim of the study is to verify whether LAC can have an antidepressant action in a population of elderly patients with dysthymic disorder in comparison with a traditional antidepressant such as fluoxetine.

METHODS

Multicentric, double-blind, double-dummy, controlled, randomized study based on a observation period of 7 weeks. 80 patients with DSM-IV diagnosis of dysthymic disorder were enrolled in the study and subdivided into 2 groups. Group A patients received LAC plus placebo; group B patients received fluoxetine 20 mg/die plus placebo. Clinical assessment was performed through several psychometric scales at 6 different moments.

RESULTS

Group A patients showed a statistically significant improvement in the following scales: HAM-D, HAM-A, BDI and Touluse Pieron Test. Comparison between the two groups, A and B, generally showed very similar clinical progression.

DISCUSSION

The results obtained with LAC and fluoxetine were equivalent. As the subjects in this study were of senile age, it is possible to hypothesize that the LAC positive effect on mood could be associated with improvement in subjective cognitive symptomatology. The difference in the latency time of clinical response (1 week of LAC treatment, compared with the 2 weeks' latency time with fluoxetine) suggests the existence of different mechanisms of action possibly in relation to the activation of rapid support processes of neuronal activity.

Chronic acetyl-L-carnitine alters brain energy metabolism and increases noradrenaline and serotonin content in healthy mice

Acetyl-L-carnitine (ALCAR), the short-chain ester of carnitine, is a common dietary supplement readily available in health food stores, claimed to improve energy levels and muscle strength. ALCAR has numerous effects on brain and muscle metabolism, protects against neurotoxic insults and may be an effective treatment for certain forms of depression. However, little is known about the effect of chronic ALCAR supplementation on the brain metabolism of healthy mice. Here, we investigated ALCAR's effect on cerebral energy and neurotransmitter metabolism after supplementing the drinking water of mice with ALCAR for 25 days, providing a daily dose of about 0.5 g/kg. Thereafter the animals were injected with [1-(13)C]glucose, and (13)C incorporation into and levels of various metabolites were quantified in extracts of the hippocampal formation (HF) and cortex using (1)H- and (13)C-nuclear magnetic resonance (NMR) spectroscopy and high performance liquid chromatography (HPLC). Increased glucose levels were detected in both regions together with a decreased amount of [3-(13)C]lactate, but no alterations in incorporation of (13)C derived from [1-(13)C]glucose into the amino acids glutamate, GABA and glutamine. These findings are consistent with decreased metabolism of glucose to lactate but not via the TCA cycle. Higher amounts of the sum of adenosine nucleotides, phosphocreatine and the phosphocreatine/creatine ratio found in the cortex of ALCAR-treated mice are indicative of increased energy levels. Furthermore, ALCAR supplementation increased the levels of the neurotransmitters noradrenaline in the HF and serotonin in cortex, consistent with ALCAR's potential efficacy for depressive symptoms. Other ALCAR-induced changes observed included reduced amounts of GABA in the HF and increased myo-inositol. In conclusion, chronic ALCAR supplementation decreased glucose metabolism to lactate, resulted in increased energy metabolite and altered monoamine neurotransmitter levels in the mouse brain.

Metabolism of acetyl-L-carnitine for energy and neurotransmitter synthesis in the immature rat brain

Acetyl-L-carnitine (ALCAR) is an endogenous metabolic intermediate that facilitates the influx and efflux of acetyl groups across the mitochondrial inner membrane. Exogenously administered ALCAR has been used as a nutritional supplement and also as an experimental drug with reported neuroprotective properties and effects on brain metabolism. The aim of this study was to determine oxidative metabolism of ALCAR in the immature rat forebrain. Metabolism was studied in 21-22 day-old rat brain at 15, 60 and 120 min after an intraperitoneal injection of [2-(13)C]acetyl-L-carnitine. The amount, pattern, and fractional enrichment of (13)C-labeled metabolites were determined by ex vivo(13)C-NMR spectroscopy. Metabolism of the acetyl moiety from [2-(13)C]ALCAR via the tricarboxylic acid cycle led to incorporation of label into the C4, C3 and C2 positions of glutamate (GLU), glutamine (GLN) and GABA. Labeling patterns indicated that [2-(13)C]ALCAR was metabolized by both neurons and glia; however, the percent enrichment was higher in GLN and GABA than in GLU, demonstrating high metabolism in astrocytes and GABAergic neurons. Incorporation of label into the C3 position of alanine, both C3 and C2 positions of lactate, and the C1 and C5 positions of glutamate and glutamine demonstrated that [2-(13)C]ALCAR was actively metabolized via the pyruvate recycling pathway. The enrichment of metabolites with (13)C from metabolism of ALCAR was highest in alanine C3 (11%) and lactate C3 (10%), with considerable enrichment in GABA C4 (8%), GLN C3 (approximately 4%) and GLN C5 (5%). Overall, our (13)C-NMR studies reveal that the acetyl moiety of ALCAR is metabolized for energy in both astrocytes and neurons and the label incorporated into the neurotransmitters glutamate and GABA. Cycling ratios showed prolonged cycling of carbon from the acetyl moiety of ALCAR in the tricarboxylic acid cycle. Labeling of compounds formed from metabolism of [2-(13)C]ALCAR via the pyruvate recycling pathway was higher than values reported for other precursors and may reflect high activity of this pathway in the developing brain. This is, to our knowledge, the first study to determine the extent and pathways of ALCAR metabolism for energy and neurotransmitter biosynthesis in the brain.

Mitochondria in the elderly: Is acetylcarnitine a rejuvenator?

Endogenous acetylcarnitine is an indicator of acetyl-CoA synthesized by multiple metabolic pathways involving carbohydrates, amino acids, fatty acids, sterols, and ketone bodies, and utilized mainly by the tricarboxylic acid cycle. Acetylcarnitine supplementation has beneficial effects in elderly animals and humans, including restoration of mitochondrial content and function. These effects appear to be dose-dependent and occur even after short-term therapy. In order to set the stage for understanding the mechanism of action of acetylcarnitine, we review the metabolism and role of this compound. We suggest that acetylation of mitochondrial proteins leads to a specific increase in mitochondrial gene expression and mitochondrial protein synthesis. In the aged rat heart, this effect is translated to increased cytochrome b content, restoration of complex III activity, and oxidative phosphorylation, resulting in amelioration of the age-related mitochondrial defect.

Carnitine insufficiency caused by aging and overnutrition compromises mitochondrial performance and metabolic control

In addition to its essential role in permitting mitochondrial import and oxidation of long chain fatty acids, carnitine also functions as an acyl group acceptor that facilitates mitochondrial export of excess carbons in the form of acylcarnitines. Recent evidence suggests carnitine requirements increase under conditions of sustained metabolic stress. Accordingly, we hypothesized that carnitine insufficiency might contribute to mitochondrial dysfunction and obesity-related impairments in glucose tolerance. Consistent with this prediction whole body carnitine diminution was identified as a common feature of insulin-resistant states such as advanced age, genetic diabetes, and diet-induced obesity. In rodents fed a lifelong (12 month) high fat diet, compromised carnitine status corresponded with increased skeletal muscle accumulation of acylcarnitine esters and diminished hepatic expression of carnitine biosynthetic genes. Diminished carnitine reserves in muscle of obese rats was accompanied by marked perturbations in mitochondrial fuel metabolism, including low rates of complete fatty acid oxidation, elevated incomplete beta-oxidation, and impaired substrate switching from fatty acid to pyruvate. These mitochondrial abnormalities were reversed by 8 weeks of oral carnitine supplementation, in concert with increased tissue efflux and urinary excretion of acetylcarnitine and improvement of whole body glucose tolerance. Acetylcarnitine is produced by the mitochondrial matrix enzyme, carnitine acetyltransferase (CrAT). A role for this enzyme in combating glucose intolerance was further supported by the finding that CrAT overexpression in primary human skeletal myocytes increased glucose uptake and attenuated lipid-induced suppression of glucose oxidation. These results implicate carnitine insufficiency and reduced CrAT activity as reversible components of the metabolic syndrome.

Acetyl-L-carnitine (ALC) in attention-deficit/hyperactivity disorder: a multi-site, placebo-controlled pilot trial

OBJECTIVE

To determine whether acetyl-L-carnitine (ALC), a metabolite necessary for energy metabolism and essential fatty acid anabolism, might help attention-deficit/hyperactivity disorder (ADHD). Trials in Down's syndrome, migraine, and Alzheimer's disease showed benefit for attention. A preliminary trial in ADHD using L-carnitine reported significant benefit.

METHOD

A multi-site 16-week pilot study randomized 112 children (83 boys, 29 girls) age 5-12 with systematically diagnosed ADHD to placebo or ALC in weight-based doses from 500 to 1500 mg b.i.d. The 2001 revisions of the Conners' parent and teacher scales (including DSM-IV ADHD symptoms) were administered at baseline, 8, 12, and 16 weeks. Analyses were ANOVA of change from baseline to 16 weeks with treatment, center, and treatment-by-center interaction as independent variables.

RESULTS

The primary intent-to-treat analysis, of 9 DSM-IV teacher-rated inattentive symptoms, was not significant. However, secondary analyses were interesting. There was significant (p = 0.02) moderation by subtype: superiority of ALC over placebo in the inattentive type, with an opposite tendency in combined type. There was also a geographic effect (p = 0.047). Side effects were negligible; electrocardiograms, lab work, and physical exam unremarkable.

CONCLUSION

ALC appears safe, but with no effect on the overall ADHD population (especially combined type). It deserves further exploration for possible benefit specifically in the inattentive type.

N-Acetylaspartate in the CNS: from neurodiagnostics to neurobiology

The brain is unique among organs in many respects, including its mechanisms of lipid synthesis and energy production. The nervous system-specific metabolite N-acetylaspartate (NAA), which is synthesized from aspartate and acetyl-coenzyme A in neurons, appears to be a key link in these distinct biochemical features of CNS metabolism. During early postnatal central nervous system (CNS) development, the expression of lipogenic enzymes in oligodendrocytes, including the NAA-degrading enzyme aspartoacylase (ASPA), is increased along with increased NAA production in neurons. NAA is transported from neurons to the cytoplasm of oligodendrocytes, where ASPA cleaves the acetate moiety for use in fatty acid and steroid synthesis. The fatty acids and steroids produced then go on to be used as building blocks for myelin lipid synthesis. Mutations in the gene for ASPA result in the fatal leukodystrophy Canavan disease, for which there is currently no effective treatment. Once postnatal myelination is completed, NAA may continue to be involved in myelin lipid turnover in adults, but it also appears to adopt other roles, including a bioenergetic role in neuronal mitochondria. NAA and ATP metabolism appear to be linked indirectly, whereby acetylation of aspartate may facilitate its removal from neuronal mitochondria, thus favoring conversion of glutamate to alpha ketoglutarate which can enter the tricarboxylic acid cycle for energy production. In its role as a mechanism for enhancing mitochondrial energy production from glutamate, NAA is in a key position to act as a magnetic resonance spectroscopy marker for neuronal health, viability and number. Evidence suggests that NAA is a direct precursor for the enzymatic synthesis of the neuron specific dipeptide N-acetylaspartylglutamate, the most concentrated neuropeptide in the human brain. Other proposed roles for NAA include neuronal osmoregulation and axon-glial signaling. We propose that NAA may also be involved in brain nitrogen balance. Further research will be required to more fully understand the biochemical functions served by NAA in CNS development and activity, and additional functions are likely to be discovered.

Brain regions involved in fatigue sensation: reduced acetylcarnitine uptake into the brain

Fatigue is an indispensable sense for ordering rest. However, the neuronal and molecular mechanisms of fatigue remain unclear. Chronic fatigue syndrome (CFS) with long-lasting fatigue sensation seems to be a good model for studying these mechanisms underlying fatigue sensation. Recently, we found that most patients with CFS showed a low level of serum acetylcarnitine, which well correlated with the rating score of fatigue, and that a considerable amount of acetyl moiety of serum acetylcarnitine is taken up into the brain. Here we show by metabolite analysis of the mouse brain that an acetyl moiety taken up into the brain through acetylcarnitine is mainly utilized for the biosynthesis of glutamate. When we studied the cerebral uptake of acetylcarnitine by using [2-(11)C]acetyl-L-carnitine in 8 patients with CFS and in 8 normal age- and sex-matched controls, a significant decrease was found in several regions of the brains of the patient group, namely, in the prefrontal (Brodmann's area 9/46d) and temporal (BA21 and 41) cortices, anterior cingulate (BA24 and 33), and cerebellum. These findings suggest that the levels of biosynthesis of neurotransmitters through acetylcarnitine might be reduced in some brain regions of chronic fatigue patients and that this abnormality might be one of the keys to unveiling the mechanisms of the chronic fatigue sensation.

Localization of messenger RNAs encoding enzymes associated with malonyl-CoA metabolism in mouse brain

Malonyl-CoA acts a fuel sensor in the pancreas, liver and muscle. Similarly, malonyl-CoA is implicated in satiety regulation in the brain. Expression of genes encoding enzymes implicated in regulation of malonyl-CoA levels was examined in murine brain. Acetyl-CoA carboxylase (ACC) alpha-isoform, fatty acid synthase and malonyl-CoA decarboxylase are highly expressed in the hippocampus, habenula nucleus, cerebral cortex and areas of the hypothalamus, whereas the ACC-beta isoform and liver-type carnitine palmitoyltransferase I (CPTI-L) are principally expressed in the choroid plexus. Thus different brain regions appear to be functionally configured primarily for either fatty acid synthesis or beta-oxidation. Localization of transcripts encoding enzymes involved in fatty acid synthesis and beta-oxidation in distinct nuclei of the hypothalamus supports a role for malonyl-CoA as a potential effector of satiety.

Efficacy of carnitine in the treatment of children with attention-deficit hyperactivity disorder

To determine safety and the efficacy of carnitine treatment in children with attention-deficit hyperactivity disorder (ADHD). The ADHD behavior was observed by parents completing the Child Behavior Checklist (CBCL) and by teachers completing the Conners teacher-rating score, in a randomized, double-blind, placebo-controlled double-crossover trial. In 13/24 boys receiving carnitine, home behavior improved as assessed with the CBCL total score (P < 0.02). In 13/24 boys, school behavior improved as assessed with the Conners teacher-rating score (P < 0.05). Before treatment, the CBCL total and sub-scores were significantly different from those of normal Dutch boys (P < 0.0001). Responders showed a significant improvement of the CBCL total scores compared to baseline (P < 0.0001). In the majority of boys no side effects were seen. At baseline and after carnitine treatment, responders showed higher levels of plasma-free carnitine (P < 0.03) and acetylcarnitine (P < 0.05). Compared to baseline, the carnitine treatment caused in the responsive patients a decrease of 20-65% (8-48 points) as assessed by the CBCL total problem rating scale. Treatment with carnitine significantly decreased the attention problems and aggressive behavior in boys with ADHD.

Straight-chain acyl-CoA oxidase knockout mouse accumulates extremely long chain fatty acids from alpha-linolenic acid: evidence for runaway carousel-type enzyme kinetics in peroxisomal beta-oxidation diseases

Extremely long chain polyunsaturated fatty acids (ELCPs) with >24 carbons and four or more double bonds are normally found in excitatory tissues but have no known function, and are greatly increased in brain and other tissues of humans with peroxisomal disorders. Straight-chain acyl-CoA oxidase (AOX) catalyzes the first, rate-limiting step of peroxisomal beta-oxidation of very-long-chain saturated and unsaturated fatty acids. We have studied the polyunsaturated fatty acid metabolism of AOX knockout mice (AOX-/- as a model of human AOX deficiency (pseudo-neonatal adrenoleukodystrophy), and as a genetic tool to test the putative peroxisomal beta-oxidation involvement in polyunsaturated fatty acid synthesis. Liver lipids of 26-day-old weanling AOX-/- mice livers accumulate n-3 and n-6 ELCPs from C24 to C30 with 5 and 6 double bonds, have 356 +/- 66 microg/g docosahexaenoic acid (22:6n-3), similar to congenic (AOX -/* = AOX+/+ and AOX+/-) controls (401 +/- 96 microg/g), but increased 22:5n-6 (22.4 +/- 3.7 vs 6.4 +/- 1.5 microg/g). AOX+/* mice injected intraperitoneally at 23 days with [U-(13)C]-18:3n-3 show strong labeling of 22:6n-3 after 72 h, whereas AOX -/- mice display less labeling of 22:6n-3 but strong tracer incorporation into 24:6n-3, 26:6n-3, and 28:6n-3, after the same period. These data suggest that ELCPs are natural runaway elongation by-products of 22:6n-3 and 22:5n-6 synthesis, which are normally disposed of by peroxisomal beta-oxidation. Under conditions with impaired peroxisomal beta-oxidation, such as Zellweger syndrome and adrenoleukodystrophies, ELCPs accumulate due to increased synthesis and impaired disposal. Two mechanisms for the formation of these runaway elongation by-products and the involvement of secondary carnitine deficiency in this process are proposed: n-3 ELCPs are synthesized by a carnitine-dependent multifunctional mitochondrial docosahexaenoic acid synthase (mtDHAS) which normally synthesizes primarily 22:6n-3, while n-6 ELCPs are synthesized by independent elongation enzymes in the endoplasmic reticulum.

Alternative treatments for adults with attention-deficit hyperactivity disorder (ADHD)

A previous review of alternative treatments (Tx) of ADHD--those other than psychoactive medication and behavioral/psychosocial Tx--was supplemented with an additional literature search focused on adults with ADHD. Twenty-four alternative Tx were identified, ranging in scientific documentation from discrediting controlled studies through mere hypotheses to positive controlled double-blind clinical trials. Many of them are applicable only to a specific subgroup. Although oligoantigenic (few-foods) diets have convincing double-blind evidence of efficacy for a properly selected subgroup of children, they do not appear promising for adults. Enzyme-potentiated desensitization, relaxation/EMG biofeedback, and deleading also have controlled evidence of efficacy. Iron supplementation, magnesium supplementation, Chinese herbals, EEG biofeedback, massage, meditation, mirror feedback, channel-specific perceptual training, and vestibular stimulation all have promising prospective pilot data, many of these tests reasonably controlled. Single-vitamin megadosage has some intriguing pilot trial data. Zinc supplementation is hypothetically supported by systematic case-control data, but no systematic clinical trial. Laser acupuncture has promising unpublished pilot data and may be more applicable to adults than children. Essential fatty acid supplementation has promising systematic case-control data, but clinical trials are equivocal. RDA vitamin supplementation, non-Chinese herbals, homeopathic remedies, and antifungal therapy have no systematic data in ADHD. Megadose multivitamin combinations are probably ineffective for most patients and are possibly dangerous. Simple sugar restriction seems ineffective. Amino acid supplementation is mildly effective in the short term, but not beyond 2-3 months. Thyroid treatment is effective in the presence of documented thyroid abnormality. Some alternative Tx of ADHD are effective or probably effective, but mainly for certain patients. In some cases, they are the Tx of choice, and initial evaluation should consider the relevant etiologies. A few have failed to prove effective in controlled trials. Most need research to determine whether they are effective and/or to define the applicable subgroup. Some of them, although not safer than standard Tx, may be preferable for an etiologic subgroup.

Assessment of dietary therapies in a canine model of Batten disease

The neuronal ceroid lipofuscinoses (NCLs) are inherited neurodegenerative diseases that occur in a number of animal species, including dogs. A study was conducted to determine whether the resupply of nutrients lost in NCL English Setter dogs would modify the course of the disease. Carnitine and polyunsaturated fatty acids have been reported to be reduced in NCL English Setters. Therefore, the normal laboratory diets of NCL dogs were supplemented with carnitine, fish oil and corn oil and the disease progression was compared with that of an untreated litter mate. The following specific prognostic indicators of NCL were monitored: cognitive function, brain atrophy, brain glucose metabolism and lifespan. Carnitine, with or without lipid supplements, dramatically delayed the progression of cognitive decline in NCL dogs. When fish oil and corn oil only were supplied, brain atrophy was reduced. A combination of all three supplements preserved cognitive function and increased lifespan by 10%. However, brain glucose hypometabolism and cerebral atrophy were not reduced. The results in this study indicated that the effectiveness of therapeutic interventions can be assessed by non-invasive methods at a relatively early stage of the disease process. Our study suggests that dietary supplementation with carnitine is a promising new approach for delaying or preventing the cognitive decline in dogs, and perhaps, with human NCL patients.

The role of the carnitine system in peroxisomal fatty acid oxidation

Peroxisomes are small, subcellular organelles that play a major role in lipid metabolism. Inherited disorders of peroxisomal structure and metabolism can result from defective assembly, missing protein import transporters, or individual enzyme deficiencies. Molecular studies helped by the range of disorders have now elucidated many of the pathways, including the paths of alpha-oxidation for phytanic acid and beta-oxidation for very-long-chain and branched-chain fatty acids and for bile acid synthesis. The mechanism of the transfer of substrates, intermediates, and products across the membrane is poorly understood. The carnitine system, known to transport activated acyl groups between localized coenzyme A pools, is presented. The evidence for the involvement of carnitine in the transfer of activated acyl groups to and from the peroxisomes is reviewed.

A function for the vitamin E metabolite alpha-tocopherol quinone as an essential enzyme cofactor for the mitochondrial fatty acid desaturases

A critical analysis of the changes in fatty acid patterns and their metabolism elicited by vitamin E deficiency leads to the proposal that a major role of dietary RRR-alpha-tocopherol (alpha-TOC) is as an enzymatic precursor of alpha-tocopherolquinone (alpha-TQ) whose semiquinone radical functions as an essential enzyme cofactor for the fatty acid desaturases of the recently elucidated carnitine-dependent, channeled, mitochondrial desaturation-elongation pathway; a detailed mechanism for its function is proposed. Pathophysiological states produced by vitamin E deficiency and alpha-TOC transfer protein defects, such as ataxia, myopathy, retinopathy, and sterility are proposed to develop from the effects of impaired alpha-TQ-dependent desaturases and the resulting deficiency of their polyenoic fatty acid products.