Stimulation of carnitine acetyltransferase in PC12 cells by nerve growth factor: relationship to choline acetyltransferase stimulation

Tolerability and efficacy of L-acetylcarnitine in patients with peripheral neuropathies: a short-term, open multicentre study

A total of 1097 patients, mean age 53.8 +/- 15 years, with peripheral mono-, multi- or polyneuropathy of various aetiologies, were enrolled in a multicentre, open-label, noncomparative, prospective clinical trial to evaluate the short-term tolerability and efficacy of L-acetylcarnitine (LAC). The drug was administered intramuscularly at a dosage of 1000 mg/day for the first 10 days, then orally at a dosage of 2000 mg/day for a further 20 days. Standard laboratory tests were used to evaluate safety and tolerability. Treatment efficacy was assessed clinically in the whole population, and in a subgroup of patients with 'lower than normal' baseline nerve conduction velocities (CVs), neurophysiological investigations were also performed at the end of the treatment period. After 30 days' therapy, there were no changes in vital signs or in blood tests. Only 18 patients reported poor tolerability of the treatment, mainly because of gastrointestinal events, and only 6 withdrew from the study because of these adverse events. The general and local (i.e. injection site) tolerability of LAC was rated highly by both patients and investigators. Neurological examination revealed that a significant percentage of patients with altered indices at baseline had normal indices by the end of the treatment period. The percentage of normalised patients varied from 11.9% for muscular trophism to 29.1% for the topographic score according to the different parameters taken into account in the neurological examination. Disease was rated as improved by 83.1% of investigators and 84.2% of patients. In patients with reduced CVs, significant increments were also recorded for motor and sensory nerves. This study demonstrates that LAC is well tolerated when given either intramuscularly or orally. The beneficial effects of short-term therapy in subjects with peripheral mono-, multi- or polyneuropathy should be confirmed by long-term studies.

Acetyl-L-carnitine in HIV-associated antiretroviral toxic neuropathy

Nucleoside analogue reverse transcriptase inhibitors (NRTIs), used as part of highly active antiretroviral therapy for the treatment of HIV and AIDS, disrupt neuronal mitochondrial DNA synthesis, resulting in antiretroviral toxic neuropathy (ATN). Acetyl-L-carnitine (ALC) enhances neurotrophic support of sensory neurons, potentially causing symptom relief and nerve regeneration, and in addition has numerous other effects on metabolic function that might be of benefit in such patients.ALC has been given to HIV patients with symptomatic ATN in a number of clinical studies administered either twice daily intramuscularly or as oral sachets or tablets. It has been shown to significantly reduce a variety of validated pain ratings, and is generally safe and well tolerated. Using a measure of neuronal innervation in standardised skin biopsies of the affected area, cutaneous nerve density has been improved by the administration of ALC in subjects with symptomatic ATN and reduced epidermal and dermal innervation, associated with clinical improvement, which was maintained over a 4-year period. Improvements were seen in both the structure and function of small sensory fibres, which were sustained over time whilst subjects received ALC. Other open-label, non-randomised studies have shown similar benefits in patients with ATN in terms of pain reduction over the short term. Further placebo-controlled studies of both treatment and prophylaxis have been completed and are under analysis to characterise further the usefulness of this pathogenesis-based therapy for ATN.

A double-blind, parallel-group, placebo-controlled, multicentre study of acetyl l-carnitine in the symptomatic treatment of antiretroviral toxic neuropathy in patients with HIV-1 infection

BACKGROUND

Nucleoside reverse transcriptase inhibitors (NRTIs) disrupt neuronal mitochondrial DNA synthesis, resulting in antiretroviral toxic neuropathy (ATN). Acetyl-L-carnitine (ALCAR) enhances neurotrophic support of sensory neurones, potentially providing symptom relief and nerve regeneration.

OBJECTIVE

The objective of the study was to assess the safety and efficacy compared to placebo of intramuscular ALCAR in HIV-positive patients with symptomatic distal symmetrical polyneuropathy.

METHODS

Ninety patients were enrolled and randomized to receive ALCAR [500 mg twice a day (bid); n=43] or placebo (n=47) intramuscularly twice daily for 14 days followed by 42 days of oral ALCAR 1000 mg bid. Assessment of pain was obtained using the Visual Analogue Scale (VAS), Total Symptom Score (TSS), Clinical Global Impression of Change, McGill Pain Questionnaire (MPQ), and the need for rescue analgesics.

RESULTS

There was no statistically significant difference in changes in VAS over 14 days between groups for the intent-to-treat (ITT) population, but for the efficacy-evaluable (EE) population ALCAR treatment produced a significantly greater reduction in pain compared with placebo (P=0.022). The proportion of patients with an improvement in TSS over 14 days was greater in the ALCAR group compared with the placebo group, but the differences were not statistically significant. During the open-label phase, patients experienced an improvement in pain, as measured by the VAS, TSS and McGill Pain Questionnaire.

CONCLUSION

ALCAR, administered twice a day intramuscularly to HIV-1-infected patients with symptomatic ATN, significantly reduced weekly mean pain ratings on the VAS compared with placebo. Treatment with oral ALCAR improved symptoms for the patient group as a whole. Intramuscular and oral ALCAR was generally safe and well tolerated.

NGF-induction of the expression of ChAT mRNA in PC12 cells and primary cultures of embryonic rat basal forebrain

The objective of this study was to examine the role of nerve growth factor (NGF) in regulation of expression of the cholinergic phenotype. NGF was administered to PC12 cells or primary cultures of embryonic (E17) rat basal forebrain for 2 days, then steady-state levels of choline acetyltransferase (ChAT) mRNA was monitored. Expression of ChAT mRNA isoforms was investigated using reverse transcription-polymerase chain reaction (RT-PCR) to amplify different upstream regions of the ChAT transcripts, and Southern blot analysis was used to verify identity of the PCR products. An NGF-induced increase of 1.8- and 1.5-fold in steady-state level of the ChAT transcript containing the M-exon (M-ChAT) was observed in PC12 cells and embryonic rat basal forebrain neurons, respectively. Also, a 2-fold increase in ChAT protein as determined by western blot analysis was associated with an NGF-mediated increase of 1.7-fold in ChAT activity in rat basal forebrain neurons within the same cultures following 4 days of NGF treatment.

Brain enzyme activities after intracerebroventricular injection of streptozotocin in rats receiving acetyl-L-carnitine

Intracerebroventricular (i.c.v.) injection of streptozotocin has been introduced as a means to inhibit glucose utilization in the rat brain, and to induce changes in neurotransmitter systems and behavior which resemble those seen in Alzheimer's disease. In this study, enzyme activities previously investigated in Alzheimer's disease (peptidases, dehydrogenases and acetyltransferases) were measured in the septum and hippocampus of control and streptozotocin-treated rats. Streptozotocin-treated rats receiving acetyl-L-carnitine were also included in the experiments, to assess possible neuroprotective effects of this substance. All enzyme activities in the septum were affected by streptozotocin, with the exception of choline acetyltransferase activity. By contrast, choline acetyltransferase activity was the only enzyme activity affected in the hippocampus. The weight of the septum was reduced in streptozotocin-treated animals. These findings indicate that i.c.v. injection of streptozotocin causes septal damage and enzymatic changes that do not closely resemble those seen in Alzheimer's disease, which are more specific. Acetyl-L-carnitine partly prevented this damage, as reflected by an attenuation of the streptozotocin-induced decrease in hippocampal choline acetyltransferase activity. This finding indicates that streptozotocin-treated rats may be valuable to test possible neuroprotective effects of drugs.