Protective Efficacy of α-Lipoic Acid on Acetylcholinesterase Activity in Aged Rat Brain Regions

Cognitive and Mood Effect of Alpha-Lipoic Acid Supplementation in a Nonclinical Elder Sample: An Open-Label Pilot Study

BACKGROUND

Memory disorders are common among elder people, and nonclinical cognitive decline is commonly experienced with age. Preclinical investigations have explored the possible role of alpha-lipoic acid (ALA), a known antioxidant compound abundant in vegetables and animal tissues, in reducing oxidative stress in the aging brain and preventing cognitive decline. However, clinical evidence is limited, and the few existing results are contrasting. In addition, while most of the existing trials have been focused on the effects of ALA administration in Alzheimer's disease (AD) or other types of dementia, studies evaluating its effects on nonclinical elder population are still missing.

METHODS

In the present open-label, pilot study, fifteen elder patients (mean age: 84.5 ± 5.77) received ALA at a daily dose of 600 mg/day for 12 weeks. General cognitive function, executive function, and mood symptom assessment were carried out at baseline and at the endpoint.

RESULTS

Overall, ALA administration was generally well-tolerated (only one dropout due to gastrointestinal side effects). However, no statistically significant effects either on cognitive function, executive function, or mood were found.

CONCLUSIONS

Despite several limitations, our study found no evidence of positive effects on cognition and mood after ALA administration in elder people without the diagnosis of AD or cognitive impairment. Further clinical trials are needed to better investigate ALA effectiveness on cognition and mood in elder subjects.

Alpha-lipoic acid in the treatment of psychiatric and neurological disorders: a systematic review

Despite the existence of many preclinical studies, scientific evidence is lacking on the clinical use of alpha-lipoic acid (ALA) for central nervous system disorders. Therefore, we aimed at revising the literature concerning the use of ALA for the treatment of psychiatric and neurological conditions and to point out what is missing for the introduction of this antioxidant to this purpose. For this systematic review we performed a search using PubMed and SCOPUS databases with the following keywords: "alpha-Lipoic Acid AND central nervous system OR psychiatric disorders OR neurological disorders OR mood disorders OR anxiety OR psychosis OR Alzheimer OR Parkinson OR stroke". The total number of references found after automatically and manually excluding duplicates was 1061. After primary and secondary screening 32 articles were selected. Regarding psychiatric disorders, the studies of ALA in schizophrenia are advanced being ALA administration related to the improvement of schizophrenia symptoms and side effects of antipsychotic medication. In neurological disorders, ALA as a supplement was effective in the prevention of Alzheimer disease progression. For stroke, the use of the supplement ALAnerv® (containing 300 mg ALA) presented important results, since it was observed a reversal of clinical parameters and oxidative imbalance in these patients. For other neurological conditions, such as encephalopathy, multiple sclerosis, traumatic brain injury, mitochondrial disorders and migraine, the results are still preliminary. Overall, there is a need of well-designed clinical trials to enhance the clinical evidences of ALA effects for the treatment of neurological and psychiatric conditions.

Neuroprotective effects of phytosterol esters against high cholesterol-induced cognitive deficits in aged rat

Accumulating epidemiological and experimental studies have confirmed that a high-cholesterol diet is detrimental to cognitive performance in animal models.

Dose-dependent effects of ladostigil on microglial activation and cognition in aged rats

The current study determined the effects of chronic treatment of aging rats with ladostigil, a cholinesterase (ChE) and monoamine oxidase (MAO) inhibitor, at doses of 1 and 8.5 mg/kg/day, on novel object recognition (NOR) and reference memory in the Morris water maze (MWM). A dose of (1 mg/kg/day) did not inhibit ChE or MAO but prevented the loss of NOR and reference memory in the MWM that occurs at 20.5 months of age. This anti-aging effect was associated with a reduction in the expression of CD11b, a marker of microglial activation, in the fornix and parietal cortex and restoration of microglial morphology to that in young adult rats. Ladostigil (8.5 mg/kg/day) inhibited brain ChE by ≈30 % and MAO A and B by 55-59 %, and had a similar, or greater effect than the low dose on microglia, but was less effective in preventing the decline in NOR. Ladostigil (8.5 mg/kg/day) may have caused too much cortical ChE inhibition and acetylcholine elevation at 16 months when NOR was intact. In support of this suggestion we showed that acute administration of ladostigil (8.5 mg/kg) worsened NOR at this age. However, at 20 months, when NOR was impaired and brain acetylcholine levels are 40 % below normal, ladostigil (8.5 mg/kg) reversed the memory deficit.

CONCLUSION

Ladostigil (1 mg/kg/day) prevents the development of age-related memory deficits by a combination of immunomodulatory and antioxidant effects. A dose causing 30 % ChE inhibition is necessary in order to reverse existing memory deficits at 20 months of age.

Rejuvenation of antioxidant and cholinergic systems contributes to the effect of procyanidins extracted from the lotus seedpod ameliorating memory impairment in cognitively impaired aged rats

The major purpose of this study was to determine the effect of procyanidins extracted from the lotus seedpod (LSPC) on the learning and memory impairments in cognitively impaired aged rats. Based on Morris water maze performance compared with young female rats, aged unimpaired (AU) and aged impaired (AI) rats were chosen from aged female rats. LSPC supplementation (50, 100 mg/kg BW, p.o.) for 7 weeks significantly improved learning and memory impairments in AI animals in the Morris water maze test, as evaluated by shortened escape latency and swimming distance. Aged rats had significantly declined antioxidant defense capacities and significantly increased lipid peroxidation and protein oxidation levels in hippocampus and cerebral cortex than young rats. Further, AI group had higher protein oxidation level compared with AU group. LSPC (50, 100 mg/kg BW, p.o.) significantly reversed the decline of antioxidant defense capacities and significantly reduced lipid peroxidation and protein oxidation levels in hippocampus and cerebral cortex of AI rats. In addition, LSPC significantly restored acetylcholine (ACh) contents and acetylcholinesterase (AChE) activities in hippocampus and cerebral cortex of AI animals. The results of this study suggest that LSPC may play a useful role in the treatment of cognitive impairment caused by Alzheimer's disease and aging.

Ladostigil prevents age-related glial activation and spatial memory deficits in rats

Oxidative stress and glial activation occur in the aging brain. Ladostigil is a new monoamine oxidase (MAO) and acetylcholinesterase (AChE) inhibitor designed for the treatment of Alzheimer's disease. It has neuroprotective and antioxidant activities in cellular models at much lower concentrations than those inhibiting MAO or AChE. When ladostigil (1mg/kg/day) was given for 6 months to 16-month-old rats it prevented the age-related increase in activated astrocytes and microglia in several hippocampal and white matter regions and increased proNGF immunoreactivity in the hippocampus towards the levels in young rats. Ladostigil also prevented the age-related reduction in cortical AChE activity and the increase in butyrylcholinesterase activity in the hippocampus, in association with the reduction in gliosis. The immunological and enzymatic changes in aged rats were associated with improved spatial memory. Ladostigil treatment had no effect on memory, glial or proNGF immunoreactivity in young rats. Early treatment with ladostigil could slow disease progression in conditions like Alzheimer's disease in which oxidative stress and inflammatory processes are present.

The Effects and Mechanisms of Mitochondrial Nutrient α-Lipoic Acid on Improving Age-Associated Mitochondrial and Cognitive Dysfunction: An Overview

We have identified a group of nutrients that can directly or indirectly protect mitochondria from oxidative damage and improve mitochondrial function and named them "mitochondrial nutrients". The direct protection includes preventing the generation of oxidants, scavenging free radicals or inhibiting oxidant reactivity, and elevating cofactors of defective mitochondrial enzymes with increased Michaelis-Menten constant to stimulate enzyme activity, and also protect enzymes from further oxidation, and the indirect protection includes repairing oxidative damage by enhancing antioxidant defense systems either through activation of phase 2 enzymes or through increase in mitochondrial biogenesis. In this review, we take alpha-lipoic acid (LA) as an example of mitochondrial nutrients by summarizing the protective effects and possible mechanisms of LA and its derivatives on age-associated cognitive and mitochondrial dysfunction of the brain. LA and its derivatives improve the age-associated decline of memory, improve mitochondrial structure and function, inhibit the age-associated increase of oxidative damage, elevate the levels of antioxidants, and restore the activity of key enzymes. In addition, co-administration of LA with other mitochondrial nutrients, such as acetyl-L: -carnitine and coenzyme Q10, appears more effective in improving cognitive dysfunction and reducing oxidative mitochondrial dysfunction. Therefore, administrating mitochondrial nutrients, such as LA and its derivatives in combination with other mitochondrial nutrients to aged people and patients suffering from neurodegenerative diseases, may be an effective strategy for improving mitochondrial and cognitive dysfunction.

Paraquat-induced Oxidative Stress in Drosophila melanogaster: Effects of Melatonin, Glutathione, Serotonin, Minocycline, Lipoic Acid and Ascorbic Acid

The efficacy of melatonin, glutathione, serotonin, minocycline, lipoic acid and ascorbic acid in counteracting the toxicity of paraquat in Drosophila melanogaster was examined. Male Oregon wild strain flies were fed for 5 days with control food or food containing the test substance. They were transferred in groups of five to vials containing only filter paper soaked with 20 mM paraquat in 5% sucrose solution. Survival was determined 24 and 48 h later. All the substances assayed increased the survival of D. melanogaster. At equimolar concentrations (0.43 mM) melatonin was more effective than serotonin, lipoic acid and ascorbic acid. However, lower concentrations of glutathione (0.22 mM) and minocycline (0.05 mM) were as efficient as melatonin. The highest survival rate (38.6%) after 48 h of paraquat treatment was found with 2.15 mM of lipoic acid. No synergistic effect of melatonin with glutathione, serotonin, minocycline, lipoic acid and ascorbic acid was detected.