OBJECTIVE

To study alterations of mitochondrial membrane potential (delta psi) and the propensity to undergo apoptosis in peripheral blood lymphocytes (PBL) from subjects with acute HIV syndrome; and to evaluate possible modulations of these phenomena by antioxidants that can be used in therapy, such as N-acetyl-cysteine (NAC), nicotinamide (NAM), or L-acetyl-carnitine (LAC).

METHODS

Mitochondrial function and the tendency of PBL to undergo spontaneous apoptosis were studied on freshly collected PBL from patients with symptomatic, acute HIV-1 primary infection, which were cultured for different durations in the presence of absence of NAC. NAM or LAC. By a cytofluorimetric method allowing analysis of delta psi in intact cells, we studied the function of these organelles under the different conditions. PBL apoptosis was evaluated by the classic cytofluorimetric method of propidium iodide staining, capable of revealing the typical DNA hypodiploid peak.

RESULTS

Significant delta psi alterations and tendency to undergo apoptosis were present in PBL from the subjects we studied. Indeed, when cultured even for a few hours in the absence of any stimulus, a consistent number of cells died. However, the presence of even different levels of NAC, NAM or LAC was able to rescue most of them from apoptosis. Both a fall in delta psi and apoptosis were evident in PBL collected in the earliest phases of the syndrome (before seroconversion), and changed significantly after a few days. A significant correlation was found between spontaneous apoptosis and tumour necrosis factor (TNF)-alpha or p24 plasma levels, as well as between apoptosis and the percentages of circulating CD4+ or CD8+ T cells.

CONCLUSIONS

PBL from patients with acute HIV syndrome are characterized by both significant mitochondrial alterations and a dramatic tendency to undergo apoptosis. The use of NAC, NAM or LAC seems to rescue cells through a protective effect on mitochondria, a well-known target for the action of TNF-alpha and for reactive oxygen species, the production of which is strongly induced by this cytokine. Thus, our data could provide the rationale for the use of such agents in addition to antiviral drugs in primary infection.

The effects of acetyl-L-carnitine (ALCAR) on metabolites involved in energy and phospholipid metabolism have been evaluated by mean of 31P and 1H NMR spectroscopy on adult (6 months) and old (24 months) rat brains. A significant increase of glycerophosphorylcholin (GroPCho) in aged rat brain has been observed as compared with adult rat brain. No variations in ATP, phosphocreatine (PCr), Cr, lactate, ADP and inorganic phosphate (Pi) levels have been found between aged and adult brains. Treatment with ALCAR caused a significant increase in PCr levels and a decrease in lactate and sugar phosphate in adult and aged rat brain. These results are suggestive of treatment with ALCAR being responsible for a reduction in brain glycolytic flow and for enhancing the utilization of alternative energy sources, such as lipid substrates or ketone bodies. Furthermore, the changes in GroPCho levels observed after treatment with ALCAR may be indicative of a modulating effect on the activity of the enzymes involved in the acylation-re-acylation process of membrane phospholipids.

During experimental hypertensive cardiac hypertrophy, the heart energy metabolism reverts from the normal adult type that obtains the majority of its requirement for adenosine triphosphate (ATP) from metabolism of fatty acids and oxidative phosphorylation (OXPHOS), to the fetal form, which metabolizes glucose and lactate. Mitochondrial synthesis and function require an estimated 1000 polypeptides, 37 of which are encoded by mitochondrial (mt) DNA, the rest by nuclear (n) DNA. Inherited or acquired aberrations of either mtDNA or nDNA mitochondrial genes cause mitochondrial dysfunction. Tissue expression of OXPHOS enzyme defects is often heterogeneous. As a result, cardiomyopathy and cardiac failure are frequent but unpredictable complications of mitochondrial encephalopathy, neuropathy, and myopathy. Several nuclear genes that encode mitochondrial proteins have been sequenced and specific defects associated with nuclear genes that affect mitochondrial structure and function have been linked to hypertrophic and dilated cardiomyopathies and to cardiac conduction defects. Thyroid hormone and exercise stimulate expression of a nuclear respiratory factor (NRF) that induces the nuclear gene TFAM, which encodes the mitochondrial transcription factor A that controls mitochondrial replication and transcription. TFAM-null mouse embryos lack mitochondria and fail to develop a heart. Mitochondrial dysfunction enhances the generation of radical oxygen species (ROS), which damage mtDNA, nDNA, proteins, and lipid membranes. Mice lacking the mitochondrial antioxidant enzyme manganese-superoxide dismutase (SOD) develop dilated cardiomyopathy. Palliative mitochondrial therapy with L-acetyl-carnitine and coenzyme Q10 improves cardiac function in patients with cardiomyopathy. Cure is only achievable by mitochondrial gene therapy. Experimental direct gene therapy uses vectors or targeting signal sequences to insert genes into mtDNA; indirect gene therapy employs viral or non-viral vectors to introduce genes into nDNA. Clinical repair of damaged somatic and germline genes that encode mitochondrial proteins may soon be within reach.

L-carnitine and acetyl-L-carnitine (ALC) are both used to improve mitochondrial function. Although it has been argued that ALC is better than l-carnitine in absorption and activity, there has been no experiment to compare the two compounds at the same dose. In the present experiment, the effects of ALC and L-carnitine on the levels of free, acyl, and total L-carnitine in plasma and brain, rat ambulatory activity, and biomarkers of oxidative stress are investigated. Aged rats (23 months old) were given ALC or L-carnitine at 0.15% in drinking water for 4 weeks. L-carnitine and ALC were similar in elevating carnitine levels in plasma and brain. Both increased ambulatory activity similarly. However, ALC decreased the lipid peroxidation (malondialdehyde, MDA) in the old rat brain, while L-carnitine did not. ALC decreased the extent of oxidized nucleotides (oxo8dG/oxo8G) immunostaining in the hippocampal CA1 and cortex, while L-carnitine did not. ALC decreased nitrotyrosine immunostaining in the hippocampal CA1 and white matter, while L-carnitine did not. In conclusion, ALC and L-carnitine were similar in increasing ambulatory activity in old rats and elevating carnitine levels in blood and brain. However, ALC was effective, unlike L-carnitine, in decreasing oxidative damage, including MDA, oxo8dG/oxo8G, and nitrotyrosine, in old rat brain. These data suggest that ALC may be a better dietary supplement than L-carnitine.

In addition to cognitive impairment, behavioral changes such as aggressive behavior, depression, and psychosis accompany Alzheimer's Disease. Such symptoms may arise due to imbalances in neurotransmitters rather than overt neurodegeneration. Herein, we demonstrate that combined administration of N-acetyl cysteine (an antioxidant and glutathione precursor that protects against A beta neurotoxicity), acetyl-L-carnitine (which raises ATP levels, protects mitochondria, and buffers A beta neurotoxicity), and S-adenosylmethionine (which facilitates glutathione usage and maintains acetylcholine levels) enhanced or maintain cognitive function, and attenuated or prevented aggression, in mouse models of aging and neurodegeneration. Enhancement of cognitive function was rapidly reversed upon withdrawal of the formulation and restored following additional rounds supplementation. Behavioral abnormalities correlated with a decline in acetylcholine, which was also prevented by this nutriceutical combination, suggesting that neurotransmitter imbalance may contribute to their manifestation. Treatment with this nutriceutical combination was able to compensate for lack of dietary folate and vitamin E, coupled with administration of dietary iron as a pro-oxidant (which collectively increase homocysteine and oxidative damage to brain tissue), indicating that it provided antioxidant neuroprotection. Maintenance of neurotransmitter levels and prevention of oxidative damage underscore the efficacy of a therapeutic approach that utilizes a combination of neuroprotective agents.

Methamphetamine (METH), an addictive psycho-stimulant drug exerts euphoric effects on users and abusers. It is also known to cause cognitive impairment and neurotoxicity. Here, we hypothesized that METH exposure impairs the glucose uptake and metabolism in human neurons and astrocytes. Deprivation of glucose is expected to cause neurotoxicity and neuronal degeneration due to depletion of energy. We found that METH exposure inhibited the glucose uptake by neurons and astrocytes, in which neurons were more sensitive to METH than astrocytes in primary culture. Adaptability of these cells to fatty acid oxidation as an alternative source of energy during glucose limitation appeared to regulate this differential sensitivity. Decrease in neuronal glucose uptake by METH was associated with reduction of glucose transporter protein-3 (GLUT3). Surprisingly, METH exposure showed biphasic effects on astrocytic glucose uptake, in which 20 µM increased the uptake while 200 µM inhibited glucose uptake. Dual effects of METH on glucose uptake were paralleled to changes in the expression of astrocytic glucose transporter protein-1 (GLUT1). The adaptive nature of astrocyte to mitochondrial β-oxidation of fatty acid appeared to contribute the survival of astrocytes during METH-induced glucose deprivation. This differential adaptive nature of neurons and astrocytes also governed the differential sensitivity to the toxicity of METH in these brain cells. The effect of acetyl-L-carnitine for enhanced production of ATP from fatty oxidation in glucose-free culture condition validated the adaptive nature of neurons and astrocytes. These findings suggest that deprivation of glucose-derived energy may contribute to neurotoxicity of METH abusers.

Although regulation of energy metabolism has been linked with multiple disorders, its role in depression and responsiveness to antidepressants is less known. We found that an epigenetic and energetic agent, acetyl-l-carnitine (LAC, oral administration), rapidly rescued the depressive- and central and systemic metabolic-like phenotype of LAC-deficient Flinders Sensitive Line rats (FSL). After acute stress during LAC treatment, a subset of FSL continued to respond to LAC (rFSL), whereas the other subset did not (nrFSL). RNA sequencing of the ventral dentate gyrus, a mood-regulatory region, identified metabolic factors as key markers predisposing to depression (insulin receptors Insr, glucose transporters Glut-4 and Glut-12, and the regulator of appetite Cartpt) and to LAC responsiveness (leptin receptors Lepr, metabotropic glutamate receptors-2 mGlu2, neuropeptide-Y NPY, and mineralocorticoid receptors MR). Furthermore, we found that stress-induced treatment resistance in nrFSL shows a new gene profile, including the metabolic regulator factors elongation of long chain fatty acids 7 (Elovllator NPAS4. Finally, while improving central energy regulation and exerting rapid antidepressant-like effects, LAC corrected a systemic hyperinsulinemia and hyperglicemia in rFSL and failed to do that in nrFSL. These findings establish CNS energy regulation as a factor to be considered for the development of better therapeutics. Agents such as LAC that regulate metabolic factors and reduce glutamate overflow could rapidly ameliorate depression and could also be considered for treatment of insulin resistance in depressed subjects. The approach here serves as a model for identifying markers and underlying mechanisms of predisposition to diseases and treatment responsiveness that may be useful in translation to human behavior and psychopathology.

Over the last 10 years, the potential therapeutic effects of nutraceuticals to prevent or delay Alzheimer's disease were proposed. Among dietary antioxidants curcumin, Ginkgo biloba and carnitines were extensively studied for their neuroprotective effects. The rationale for this alternative therapeutic approach was based on several preclinical studies which suggested the neuroprotective effects for curcumin, Ginkgo biloba and acetyl-l-carnitine due to either a free radical scavenging activity or the inhibition of pro-inflammatory pathways or the potentiation of the cell stress response. However, although these are interesting premises, clinical studies were not able to demonstrate significant beneficial effects of curcumin, Ginkgo biloba and acetyl-l-carnitine in improving cognitive functions in Alzheimer's disease patients. The aim of this review is to summarize the main pharmacologic features of curcumin, Ginkgo biloba and carnitines as well as to underlie the main outcomes reached by clinical studies designed to demonstrate the efficacy of these natural substances in Alzheimer's disease patients. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

Acetyl-L-carnitine (ALC) is a naturally occurring molecule with an important role in cellular bioenergetics and as donor of acetyl groups to proteins, including NF-κB p65. In humans, exogenously administered ALC has been shown to be effective in mood disturbances, with a good tolerability profile. No current information is available on the antidepressant effect of ALC in animal models of depression and on the putative mechanism involved in such effect. Here we report that ALC is a proneurogenic molecule, whose effect on neuronal differentiation of adult hippocampal neural progenitors is independent of its neuroprotective activity. The in vitro proneurogenic effects of ALC appear to be mediated by activation of the NF-κB pathway, and in particular by p65 acetylation, and subsequent NF-κB-mediated upregulation of metabotropic glutamate receptor 2 (mGlu2) expression. When tested in vivo, chronic ALC treatment could revert depressive-like behavior caused by unpredictable chronic mild stress, a rodent model of depression with high face validity and predictivity, and its behavioral effect correlated with upregulated expression of mGlu2 receptor in hippocampi of stressed mice. Moreover, chronic, but not acute or subchronic, drug treatment significantly increased adult born neurons in hippocampi of stressed and unstressed mice. We now propose that this mechanism could be potentially involved in the antidepressant effect of ALC in humans. These results are potentially relevant from a clinical perspective, as for its high tolerability profile ALC may be ideally employed in patient subpopulations who are sensitive to the side effects associated with classical antidepressants.

Injury to sensory afferents may contribute to the peripheral neuropathies that develop after administration of chemotherapeutic agents. Manipulations that increase levels of nicotinamide adenine dinucleotide (NAD) can protect against neuronal injury. This study examined whether nicotinamide riboside (NR), a third form of vitamin B3 and precursor of NAD, diminishes tactile hypersensitivity and place escape-avoidance behaviors in a rodent model of paclitaxel-induced peripheral neuropathy. Female Sprague-Dawley rats received 3 intravenous injections of 6.6 mg/kg paclitaxel over 5 days. Daily oral administration of 200 mg/kg NR beginning 7 days before paclitaxel treatment and continuing for another 24 days prevented the development of tactile hypersensitivity and blunted place escape-avoidance behaviors. These effects were sustained after a 2-week washout period. This dose of NR increased blood levels of NAD by 50%, did not interfere with the myelosuppressive effects of paclitaxel, and did not produce adverse locomotor effects. Treatment with 200 mg/kg NR for 3 weeks after paclitaxel reversed the well-established tactile hypersensitivity in a subset of rats and blunted escape-avoidance behaviors. Pretreatment with 100 mg/kg oral acetyl-L-carnitine (ALCAR) did not prevent paclitaxel-induced tactile hypersensitivity or blunt escape-avoidance behaviors. ALCAR by itself produced tactile hypersensitivity. These findings suggest that agents that increase NAD, a critical cofactor for mitochondrial oxidative phosphorylation systems and cellular redox systems involved with fuel utilization and energy metabolism, represent a novel therapeutic approach for relief of chemotherapy-induced peripheral neuropathies. Because NR is a vitamin B3 precursor of NAD and a nutritional supplement, clinical tests of this hypothesis may be accelerated.

OBJECTIVE

To determine the effect of oral carnitine supplementation on the semen parameters of men with idiopathic asthenospermia.

METHODS

Prospective, randomized, double-blind placebo-controlled study.

METHODS

Academic tertiary referral centers.

METHODS

Male patients presenting with infertility and with sperm motility of 10%-50% were selected.

METHODS

Patients were randomized to 24-week treatment arms of oral carnitine (2,000 mg L-carnitine and 1,000 mg L-acetyl-carnitine per day) or placebo.

METHODS

Sperm motility and total motile sperm counts at baseline, 12 weeks, and 24 weeks. Seminal plasma and sperm free, acetyl, and total L-carnitine levels at baseline and at week 24.

RESULTS

Twenty-one patients entered the study, with 12 patients in the carnitine arm and 9 in the placebo arm. There were no significant differences in baseline semen parameters between the carnitine and placebo arms. There was no statistically significant or clinically significant increase in motility or total motile sperm counts between baseline, 12 week, or 24 weeks in the carnitine or placebo arms.

CONCLUSIONS

Carnitine supplementation demonstrated no clinically or statistically significant effect on sperm motility or total motile sperm counts in men with idiopathic asthenospermia.

OBJECTIVE

To To compare testosterone undecanoate versus propionyl-L-carnitine plus acetyl-L-carnitine and placebo in the treatment of male aging symptoms.

METHODS

A total of 120 patients were randomized into three groups. The mean patient age was 66 years (range 60 to 74). Group 1 was given testosterone undecanoate 160 mg/day, the second group was given propionyl-L-carnitine 2 g/day plus acetyl-L-carnitine 2 g/day. The third group was given a placebo (starch). Drugs and placebo were given for 6 months. The assessed variables were total prostate-specific antigen, prostate volume, peak systolic velocity, end-diastolic velocity, resistive index of cavernosal penile arteries, nocturnal penile tumescence, total and free testosterone, prolactin, luteinizing hormone, International Index of Erectile Function score, Depression Melancholia Scale score, fatigue scale score, and incidence of side effects. The assessment was performed at intervals before, during, and after therapy.

RESULTS

Testosterone and carnitines significantly improved the peak systolic velocity, end-diastolic velocity, resistive index, nocturnal penile tumescence, International Index of Erectile Function score, Depression Melancholia Scale score, and fatigue scale score. Carnitines proved significantly more active than testosterone in improving nocturnal penile tumescence and International Index of Erectile Function score. Testosterone significantly increased the prostate volume and free and total testosterone levels and significantly lowered serum luteinizing hormone; carnitines did not. No drug significantly modified prostate-specific antigen or prolactin. Carnitines and testosterone proved effective for as long as they were administered, with suspension provoking a reversal to baseline values. Only the group 1 prostate volume proved significantly greater than baseline 6 months after testosterone suspension. Placebo administration proved ineffective. Negligible side effects emerged.

CONCLUSIONS

Testosterone and, especially, carnitines proved to be active drugs for the therapy of symptoms associated with male aging.

Lysine acetylation (AcK), a posttranslational modification wherein a two-carbon acetyl group binds covalently to a lysine residue, occurs prominently on mitochondrial proteins and has been linked to metabolic dysfunction. An emergent theory suggests mitochondrial AcK occurs via mass action rather than targeted catalysis. To test this hypothesis, we performed mass spectrometry-based acetylproteomic analyses of quadriceps muscles from mice with skeletal muscle-specific deficiency of carnitine acetyltransferase (CrAT), an enzyme that buffers the mitochondrial acetyl-CoA pool by converting short-chain acyl-CoAs to their membrane permeant acylcarnitine counterparts. CrAT deficiency increased tissue acetyl-CoA levels and susceptibility to diet-induced AcK of broad-ranging mitochondrial proteins, coincident with diminished whole body glucose control. Sub-compartment acetylproteome analyses of muscles from obese mice and humans showed remarkable overrepresentation of mitochondrial matrix proteins. These findings reveal roles for CrAT and L-carnitine in modulating the muscle acetylproteome and provide strong experimental evidence favoring the nonenzymatic carbon pressure model of mitochondrial AcK.

Alterations in brain metabolism after ischemia and reperfusion are described herein. Several roles played by carnitine and acetylcarnitine can be of particular relevance in counteracting these brain metabolism alterations. The effects of acetylcarnitine in several experimental models of brain ischemia in rats are described. The data obtained show that acetylcarnitine can have significant clinical neuroprotective effects when administered shortly after the onset of focal or global cerebral ischemia. In the canine cardiac arrest model, acetylcarnitine improved the postischemic neurological outcome and tissue levels of lactate and pyruvate were normalized. A trend toward reversal of pyruvate dehydrogenase inhibition in acetylcarnitine-treated dogs was also observed. The immediate postischemic administration of acetylcarnitine prevents free radical-mediated protein oxidation in the frontal cortex of dogs submitted to cardiac arrest and resuscitation. The transfer of the acetyl group to coenzyme A (CoA) to form acetyl-CoA as the primary source of energy is a plausible mechanism of action of acetylcarnitine.

Several pathologies related to nervous tissue alterations are characterized by a chronic pain syndrome defined by persistent or paroxysmal pain independent or dependent on a stimulus. Pathophysiological mechanisms related to neuropathic disease are associated with mitochondrial dysfunctions that lead to an activation of the apoptotic cascade. In a model of peripheral neuropathy obtained by the loose ligation of the rat sciatic nerve, acetyl-L-Carnitine (ALCAR; 100 mg/kg intraperitoneally [i.p.] twice daily for 14 days) was able to reduce hyperalgesia and apoptosis. In the present study, different mechanisms for the analgesic and the antineuropathic effect of ALCAR are described. The muscarinic blocker atropine (5 mg/kg i.p.) injected simultaneously with ALCAR did not antagonize the ALCAR antihyperalgesic effect on the paw-pressure test but significantly reduced the analgesic effect of ALCAR. Conversely, the antineuropathic effect of ALCAR was prevented by cotreatment with the nicotinic antagonist mecamylamine (2 mg/kg i.p. twice daily for 14 days). A pharmacological silencing of the nicotinic receptors significantly reduced the X-linked inhibitor of apoptosis protein-related protective effect of ALCAR on the apoptosis induced by ligation of the sciatic nerve. Taken together, these data highlight the relevance of nicotinic modulation in neuropathy treatment.

The control of fatty acid oxidation in heart is reviewed with special emphasis on the energy-linked regulation of this process. Studies with perfused working hearts and isolated mitochondria have revealed an inverse relationship between the energy-dependent rate of fatty acid oxidation and the intramitochondrial ratio of [acetyl-CoA]:[free CoA] at sufficiently high concentrations of fatty acids. Studies with isolated enzymes demonstrated a strong inhibition of 3-ketoacyl-CoA thiolase by acetyl-CoA at low concentrations of free CoA. Together these observations prompted the proposal that the rate of fatty acid oxidation is tuned to the energy demand of heart via the regulation of 3-ketoacyl-CoA thiolase by the [acetyl-CoA]:[free CoA] ratio. Evidence in support of this regulatory model has been obtained with isolated rat heart mitochondria in which either the activity of 3-ketoacyl-CoA thiolase was decreased by use of mechanism-based inhibitors or the intramitochondrial ratio of [acetyl-CoA]:[free CoA] was adjusted with L-carnitine. Because intermediates of beta-oxidation normally do not accumulate in mitochondria, it remains unclear how the entry of fatty acyl-CoA into the beta-oxidation spiral is tuned to the activity of 3-ketoacyl-CoA thiolase. A control of fatty acid oxidation in heart via the regulation of carnitine palmitoyltransferase I by malonyl-CoA has not been established even though malonyl-CoA is present in this tissue and strongly inhibits myocardial carnitine palmitoyltransferase I.

P19 teratoma cells differentiate to neural-like cells in the presence of retinoic acid. If they are plated in N2 synthetic, serum-free medium without being exposed to retinoic acid, they die within 48-72 h. This model has allowed the discovery of the neuron survival-promoting capacity of activin. We have studied the death process triggered by serum removal, and showed that it has the characteristics of apoptosis. In addition we have used this model to study the mechanism of action of L-acetyl-carnitine. This endogenous molecule has been successfully employed as a drug retarding Alzheimer's disease progression. Many pharmacological actions have been reported for this compound. However, so far, it has been difficult to explain the observed results with a single mechanism of action. We have demonstrated that the addition of 100 microM L-acetylcarnitine to the N2 medium, at the time of plating, enhances cell survival, retarding DNA fragmentation and nuclear condensation. We have ruled out the possibility of a role of oxidative stress in the activation of apoptosis, under our conditions. Therefore the protective action of L-acetylcarnitine does not seem to be due to a putative antioxidant activity. Our data, demonstrating a retardation by L-acetylcarnitine of apoptotic cell death, could provide a unifying hypothesis for the explanation of several described actions of this drug. In the view that some of the degenerative diseases in the nervous system could be due to the presence of abnormal stimuli, or the absence of trophic factors that trigger programmed cell death, this model of serum deprivation-induced cell death seems to be relevant for the study of neuroprotective molecules.

Dementias and other severe cognitive dysfunction states pose a daunting challenge to existing medical management strategies. An integrative, early intervention approach seems warranted. Whereas, allopathic treatment options are highly limited, nutritional and botanical therapies are available which have proven degrees of efficacy and generally favorable benefit-to-risk profiles. This review covers five such therapies: phosphatidylserine (PS), acetyl-l-carnitine (ALC), vinpocetine, Ginkgo biloba extract (GbE), and Bacopa monniera (Bacopa). PS is a phospholipid enriched in the brain, validated through double-blind trials for improving memory, learning, concentration, word recall, and mood in middle-aged and elderly subjects with dementia or age-related cognitive decline. PS has an excellent benefit-to-risk profile. ALC is an energizer and metabolic cofactor which also benefits various cognitive functions in the middle-aged and elderly, but with a slightly less favorable benefit-to-risk profile. Vinpocetine, found in the lesser periwinkle Vinca minor, is an excellent vasodilator and cerebral metabolic enhancer with proven benefits for vascular-based cognitive dysfunction. Two meta-analyses of GbE demonstrate the best preparations offer limited benefits for vascular insufficiencies and even more limited benefits for Alzheimer's, while "commodity" GbE products offer little benefit, if any at all. GbE (and probably also vinpocetine) is incompatible with blood-thinning drugs. Bacopa is an Ayurvedic botanical with apparent anti-anxiety, anti-fatigue, and memory-strengthening effects. These five substances offer interesting contributions to a personalized approach for restoring cognitive function, perhaps eventually in conjunction with the judicious application of growth factors.

The energy-linked processes (transmembrane potential and oxidative phosphorylation) resulted in impaired mitochondria isolated from ischemic perfused rat hearts. Addition of 1.5 mM L-propionyl-carnitine to the perfusate significantly reduced the ischemic damage and ameliorated mitochondrial Ca2+ homeostasis. In both normoxic and ischemic hearts perfused with L-propionyl-carnitine a consistent amount of propionyl-CoA-otherwise undetectable-was produced. L-propionyl-carnitine treatment also prevented the decrease of succinyl-CoA associated with the ischemic condition. These results and the decrease of myocardial acetyl-CoA induced by exogenous L-propionyl-carnitine points to the anaplerotic effect of this ester. The consequently improved flux in the tricarboxylic-acid cycle may account for the observed protection of mitochondrial functions afforded by L-propionyl-carnitine in the ischemic perfused hearts.

The effects of acetyl-L-carnitine (ALCAR) treatment on brain energy state recovery and lactic acid levels following 20 min ischemia and 2, 24 and 48 h reperfusion were investigated by 31P and 1H-NMR spectroscopy. Transient forebrain ischemia was induced by four-vessel occlusion method in fed 6-month-old Fischer rats. ALCAR or saline was administered by intraperitoneal route immediately after 20 min ischemia and again at 1, 4, 24 and 30 h during reperfusion. Twenty-min severe forebrain ischemia was associated with a marked decrease in phosphocreatine (PCr) and ATP levels and a corresponding increase in lactic acid, inorganic phosphate (Pi), AMP, creatine, glycerol 3-phosphate and alanine levels. Following reperfusion, a general tendency to restore pre-ischemic metabolite levels was observed. However, after 2 h reperfusion in saline-treated rats, lactic acid and Pi levels remained significantly higher, while ATP levels were still significantly lower than in non-ischemic controls. On the contrary, in ALCAR-treated animals a complete recovery of all metabolites including Pi and ATP was observed, while PCr levels were even more elevated compared with those in saline-treated rats. Furthermore lactic acid content was significantly lower than that in both saline-treated and non-ischemic control rats. It is concluded that a potential therapeutic role may be claimed for ALCAR in the treatment of cerebral ischemia through mechanisms that include faster recovery and improvement of brain energy production as well as a decreased lactic acid content during early post-ischemic reperfusion.

Propionyl-CoA is formed principally during amino acid catabolism. It is then converted chiefly to succinate in a described three-step sequence. Free propionate is formed from propionyl-CoA to a very limited extent, but this anion can participate in a futile cycle of activation and hydrolysis, which can significantly deplete mitochondrial ATP. Free CoA and propionyl-CoA cannot enter or leave mitochondria, but propionyl groups are transferred between separate CoA pools by prior conversion to propionyl-L-carnitine. This reaction requires carnitine and carnitine acetyl transferase, an enzyme abundant in heart tissue. Propionyl-L-carnitine traverses both mitochondrial and cell membranes. Within the cell, this mobility helps to maintain the mitochondrial acyl-CoA/CoA ratio. When this ratio is increased, as in carnitine deficiency states, deleterious consequences ensue, which include deficient metabolism of fatty acids and urea synthesis. From outside the cell (in blood plasma), propionyl-L-carnitine can either be excreted in the urine or redistributed by entering other tissues. This process apparently occurs-without prior hydrolysis and reformation. It is suggested that heart tissue utilizes such exogenous propionyl-L-carnitine to stimulate the tricarboxylic acid cycle (via succinate synthesis) and that this may explain its known protective effect against ischemia.

1. CoA, acetyl-CoA, l-carnitine and acetyl-l-carnitine when added to rat liver mitochondria equilibrate with approximately two-thirds of the total intramitochondrial water. The mitochondrial space calculated to be freely permeable to these solutes was identical with that obtained for sucrose. 2. Acetyl-CoA is rapidly deacylated by rat liver mitochondria at 0 degrees C, and special precautions are required to measure its mitochondrial permeation. 3. Rat liver mitochondria were separated into fractions that correspond to the inner membrane, the outer membrane, and the soluble proteins of the matrix and intermembrane compartment. Soluble enzymes considered to be located in the matrix were citrate synthase (EC 4.1.3.7), palmitoyl-CoA dehydrogenase (EC 1.3.2.2), electron-transferring flavoprotein, medium-chain-length ATP-specific fatty acyl-CoA synthetase (EC 6.2.1.2), l-3-hydroxybutyryl-CoA dehydrogenase (EC 1.1.1.35) and 3-keto-acyl-CoA thiolase (EC 2.3.1.16). Carnitine palmitoyltransferase (EC 2.3.1.-) is largely associated with the inner-membrane fraction. A long-chain-length ATP-specific fatty acyl-CoA synthetase (EC 6.2.1.3) is associated with the outer-membrane fraction.

BACKGROUND

Nucleoside analogue reverse transcriptase inhibitors (NRTIs) used for the treatment of HIV can a cause distal symmetrical peripheral polyneuropathy by disruption of mitochondrial metabolism. Treatment with acetyl-L-carnitine (ALCAR) has shown short-term symptomatic and histological improvement. Long-term effects have not been investigated.

OBJECTIVE

To assess the subjective and objective degree of antiretroviral toxic neuropathy (ATN) during treatment with ALCAR.

METHODS

A cohort of 21 patients with ATN who commenced treatment with ALCAR between March 1999 and October 2001 was reviewed after a mean of 4.3 years using standardized questionnaires and neurological examination.

RESULTS

Of the 21 patients, 2 had died and 3 were lost to follow-up. 16 patients were assessed. 10 were still on potentially neurotoxic drugs. 13 were still taking ALCAR. 9 were pain free. The most common symptom was numbness (mild, moderate, and severe in 12, 3, and 0 patients, respectively), followed by paraesthesia (8, 2, 2), pain (4, 3, 0), and burning (5, 2, 0). There was mildly reduced sensation in the toes of 8 patients. 13 patients reported that ALCAR had improved their symptoms very much or moderately, 2 reported no change, and 1 reported a moderate worsening.

CONCLUSIONS

ALCAR led to long-term symptomatic improvement in most patients without the need to discontinue neurotoxic drugs. Although in this study there was no control group, this agent appears to be an effective pathogenesis-based treatment for ATN.

The mechanism for the pathological increase in cell death in various disease states e.g. HIV immunodefficiency or even ageing or Alzheimer's disease, occurs by complex and as yet undefined mechanism(s) related to immunological, virological or biochemical disturbances (i.e. energy depletion, oxidative stress, increased protein degradation). We have studied mitochondrial uncoupling or inhibitor toxicity on neurones at the cellular level and at the mitochondrial level using rhodamine (Rh123) and 10-nonylacridine orange (NAO) fluorescence with confocal microscopy. Blockade of the mitochondrial chain complexes at various points was studied. The possible protective effects of the compound L-carnitine, which plays a central role in mitochondrial function, was tested in this form of neurotoxicity. It appears that L-carnitine and its acetylated form, acetyl-L-carnitine, can attenuate the cell damage, as assessed by lactate dehydrogenase (LDH) release, evoked by the uncoupler, p-(trifluoromethoxy)phenylhdyrazone (FCCP), or by the inhibitors, 3-nitropropionic acid (3-NPA) or rotenone. Further, the FCCP-induced inhibition of Rh123 uptake was antagonized by the preincubation of cells with L-carnitine. Since such neurotoxic mechanisms may be operating in the various pathological forms of myotoxicity and neurotoxicity, these observations suggest potential for a therapeutic approach.