Life Extension Magazine

Life Extension Magazine September 2006

Abstracts

Carnitine

Acetyl-L-carnitine-induced up-regulation of heat shock proteins protects cortical neurons against amyloid-beta peptide 1-42-mediated oxidative stress and neurotoxicity: Implications for Alzheimer’s disease.

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by loss of memory and cognition and by senile plaques and neurofibrillary tangles in brain. Amyloid-beta peptide, particularly the 42-amino-acid peptide (Abeta(1-42)), is a principal component of senile plaques and is thought to be central to the pathogenesis of the disease. The AD brain is under significant oxidative stress, and Abeta(1-42) peptide is known to cause oxidative stress in vitro and in vivo. Acetyl-L-carnitine (ALCAR) is an endogenous mitochondrial membrane compound that helps to maintain mitochondrial bioenergetics and lowers the increased oxidative stress associated with aging. Glutathione (GSH) is an important endogenous antioxidant, and its levels have been shown to decrease with aging. Administration of ALCAR increases cellular levels of GSH in rat astrocytes. In the current study, we investigated whether ALCAR plays a protective role in cortical neuronal cells against Abeta(1-42)-mediated oxidative stress and neurotoxicity. Decreased cell survival in neuronal cultures treated with Abeta(1-42) correlated with an increase in protein oxidation (protein carbonyl, 3-nitrotyrosine) and lipid peroxidation (4-hydroxy-2-nonenal) formation. Pretreatment of primary cortical neuronal cultures with ALCAR significantly attenuated Abeta(1-42)-induced cytotoxicity, protein oxidation, lipid peroxidation, and apoptosis in a dose-dependent manner. Addition of ALCAR to neurons also led to an elevated cellular GSH and heat shock proteins (HSPs) levels compared with untreated control cells. Our results suggest that ALCAR exerts protective effects against Abeta(1-42) toxicity and oxidative stress in part by up-regulating the levels of GSH and HSPs. This evidence supports the pharmacological potential of acetyl carnitine in the management of Abeta(1-42)-induced oxidative stress and neurotoxicity. Therefore, ALCAR may be useful as a possible therapeutic strategy for patients with AD.

J Neurosci Res. 2006 Apr 21

Antioxidant activity of propionyl-L-carnitine in liver and heart of spontaneously hypertensive rats.

Oxidative stress plays an important role in arterial hypertension and propionyl-L-carnitine (PLC) has been found to protect cells from toxic reactive oxygen species. In this work, we have evaluated the antioxidant capacity of chronic PLC treatment in spontaneously hypertensive rats (SHR) by measuring the activity of antioxidant enzymes and the lipid peroxidation in liver and cardiac tissues. The activity of glutathione peroxidase was decreased in liver and cardiac tissues of SHR when compared with their normotensive controls, Wistar- Kyoto (WKY) rats, this alteration being prevented by PLC treatment. Glutathione reductase activity was increased in hypertensive rats and no effect was observed after the treatment. No significant changes in superoxide dismutase activity were observed among all experimental groups. Liver of hypertensive rats showed higher catalase activity than that of normotensive rats, and PLC enhanced this activity in both rat strains. Thiobarbituric acid reactive substances, determined as a measure of lipid peroxidation, were increased in SHR compared with WKY rats, and PLC treatment decreased these values not only in hypertensive rats but also in normotensive ones. The content of carnitine in serum, liver and heart was higher in PLC-treated rats, but PLC did not prevent the hypertension development in young SHR. In addition, triglyceride levels, which were lower in SHR than WKY rats, were reduced by chronic PLC treatment in both rat strains. These results demonstrate: i) the hypotriglyceridemic effect of PLC and ii) the antioxidant capacity of PLC in SHR and its beneficial use protecting tissues from hypertension-accompanying oxidative damage.

Life Sci. 2006 Mar 20;78(17):1945-52

A double-blind, randomised, controlled clinical trial of acetyl-L-carnitine vs. amisulpride in the treatment of dysthymia.

AIM: Evaluation of the effect of acetyl-L-carnitine (ALCAR) vs. amisulpride measured by total Hamilton Depression Rating Scale score (HAM-D(21)) in patients with pure dysthymia (DSM IV). Two hundred and four patients were randomised and treated with ALCAR 500 mg b.i.d. or amisulpride 50 mg u.i.d. in a double-blind study, for 12 weeks. RESULTS: A solid improvement of HAM-D(21) was observed in both treatment groups throughout the study. The results did not disclose statistically significant differences between treatments, although the confidence interval for the non-inferiority of the primary end-point exceeded the pre-established limit of 2 by 0.46 points. According to a non-inferiority margin of 3 (considered acceptable by recent published data) the primary end-point could have been fully satisfied. CDRS, MADRS and CGI, employed to further measure the clinical outcome, reported similar results in both treatment groups. The greater tolerability of ALCAR is of clinical relevance considering the chronicity of dysthymia, which often requires prolonged treatment.

Eur Neuropsychopharmacol. 2006 May;16(4):281-7

Acetyl-l-carnitine in the treatment of painful antiretroviral toxic neuropathy in human immunodeficiency virus patients: an open label study.

Antiretroviral toxic neuropathy causes morbidity in human immunodeficiency virus (HIV) patients under dideoxynucleoside therapy, benefits only partially from medical therapy, and often leads to drug discontinuation. Proposed pathogeneses include a disorder of mitochondrial oxidative metabolism, eventually related to a reduction of mitochondrial DNA content, and interference with nerve growth factor activity. Carnitine is a substrate of energy production reactions in mitochondria and is involved in many anabolic reactions. Acetyl carnitine treatment promotes peripheral nerve regeneration and has neuroprotective properties and a direct analgesic role related to glutamatergic and cholinergic modulation. The aim of this study was to evaluate acetyl-l-carnitine in the treatment of painful antiretroviral toxic neuropathy in HIV patients. Twenty subjects affected by painful antiretroviral toxic neuropathy were treated with oral acetyl-l-carnitine at a dose of 2,000 mg/day for a 4-week period. Efficacy was evaluated by means of the modified Short Form McGill Pain Questionnaire with each item rated on an 11-point intensity scale at weekly intervals and by electromyography at baseline and final visit. Mean pain intensity score was significantly reduced during the study, changing from 7.35 +/- 1.98 (mean +/- SD) at baseline to 5.80 +/- 2.63 at week 4 (p = 0.0001). Electrophysiological parameters did not significantly change between baseline and week 4. In this study, acetyl-l-carnitine was effective and well tolerated in symptomatic treatment of painful neuropathy associated with antiretroviral toxicity. On the contrary, no effect was noted on neurophysiological parameters.

J Peripher Nerv Syst. 2006 Mar;11(1):72-6

Symptomatic and neurophysiological responses of paclitaxel- or cisplatin-induced neuropathy to oral acetyl-L-carnitine.

Acetyl-L-carnitine (ALC) improves non-oncological neuropathies. We tested oral ALC (1 g tid) for 8 weeks in 25 patients with neuropathy grade 3 (common toxicity criteria--CTC) during paclitaxel or cisplatin therapy, or grade 2 persisting for at least three months after discontinuing the drugs. An independent neurologist assessed patients before and after ALC. All patients except one reported symptomatic relief, and only two described grade 1 nausea. The sensory neuropathy grade improved in 15 of 25 (60%), and motor neuropathy in 11 of 14 patients (79%). Total neuropathy score (TNS) that included neurophysiological measures improved in 23 (92%). Amelioration of sensory amplitude and conduction velocity (sural and peroneal nerves) was measured in 22 and 21 patients, respectively. Symptomatic improvement persisted in 12 of 13 evaluable patients at median 13 months after ALC. In view of its effect in improving established paclitaxel- and cisplatin-neuropathy, we recommend ALC testing in preventing progression or revert symptoms during neurotoxic chemotherapy.

Eur J Cancer. 2005 Aug;41(12):1746-50