Increased peroxidation and reduced antioxidant enzyme activity in Alzheimer's disease

Synthesis of novel steroidal curcumin derivatives as anti-Alzheimer's disease candidates: Evidences-based on in vivo study

Alzheimer's disease (AD) is a complex disease in which a single monofunctional 'targeted' drug is uneffective for management. Hybrid drugs that impact multiple targets simultaneously are better at controlling such complex disease systems. Hybrid agents were synthesized through the combination of the steroid moiety with curcumin molecule. Also novel curcumin analogues containing promising heterocyclic nucleus fused to the essential pharmacophoric feature of the curcumin moiety, were synthesized. The aim of the present study was extended to elucidate the efficacy of these novel synthesized compounds in the regression of AD induced in adult female albino rats. The results revealed that treatment of AD groups with compounds 3, 5, 8c or rivastigmin experienced significant increase in brain Ach, GSH, paraoxenase and BCL2 levels with respect to untreated group associated with significant decrease in brain AchE activity, urinary 8-OHG level, serum Caspase-3 level and brain P53 level relative to the untreated group. Immunohistochemical investigation revealed that the selected treatments caused marked increase in ChAT positive cells. These findings were documented by the histological investigation of the brain tissue. The activity of tested compounds showed gradual increase from compound b followed by compound 8c then compound 5. The anti-cholinesterase potential, anti-oxidant properties and anti-apoptotic activity are responsible for the anti-Alzheimer's disease potential of these compounds.

Effects of an antioxidant beverage on biomarkers of oxidative stress in Alzheimer's patients

PURPOSE

The purpose of the study was to test whether daily consumption of a beverage with high antioxidant power, combining extracts of green tea and apple over a period of 8 months, would affect blood and urinary concentrations of biomarkers of oxidative stress in Alzheimer's patients.

METHODS

The study included 100 subjects, 48 of them were Alzheimer's patients, aged 76.5 ± 3.5 years, and 52 were control subjects, aged 79 ± 4 years, without dementia. Three blood and urine samples were taken from each participant, the first (T i) before starting the antioxidant or placebo beverage intake, the second (T m) 4 months after the antioxidant or placebo beverage intake and the third (T f) 8 months after the antioxidant or placebo beverage intake, and concentrations of biomarkers of oxidative stress were measured on serum, lysed erythrocytes or urine by UV-Vis spectrophotometry or by competitive in vitro enzyme-linked immunosorbent assay, according to the parameter analyzed.

RESULTS

The administration of the antioxidant beverage to the Alzheimer's patients prevented the decrease in total antioxidant status in the moderate phase of the disease (T i = 1.40 ± 0.10 mmol/L vs T f = 1.20 ± 0.08 mmol/L), increased values of glutathione peroxidase and superoxide dismutase in initial (165 and 24 % respectively) and moderate phase (75 and 85 % respectively), and prevented the increase in protein carbonyls in moderate phase (T i = 0.17 ± 0.07 nmol/mg protein vs T f = 0.21 ± 0.06 nmol/mg protein), with a significant decrease in protein carbonyls since the fourth month of the intake in initial phase (T m = 0.21 ± 0.06 nmol/mg protein vs T f = 0.11 ± 0.05 nmol/mg protein).

CONCLUSION

Our results suggest that antioxidant beverage could be used as a natural complementary therapy for alleviate or decrease the oxidative stress effects in the stages of Alzheimer's disease.

Docosahexaenoic (DHA) modulates phospholipid-hydroperoxide glutathione peroxidase (Gpx4) gene expression to ensure self-protection from oxidative damage in hippocampal cells

Docosahexaenoic acid (DHA, 22:6n-3) is a unique polyunsaturated fatty acid particularly abundant in nerve cell membrane phospholipids. DHA is a pleiotropic molecule that, not only modulates the physicochemical properties and architecture of neuronal plasma membrane, but it is also involved in multiple facets of neuronal biology, from regulation of synaptic function to neuroprotection and modulation of gene expression. As a highly unsaturated fatty acid due to the presence of six double bonds, DHA is susceptible for oxidation, especially in the highly pro-oxidant environment of brain parenchyma. We have recently reported the ability of DHA to regulate the transcriptional program controlling neuronal antioxidant defenses in a hippocampal cell line, especially the glutathione/glutaredoxin system. Within this antioxidant system, DHA was particularly efficient in triggering the upregulation of Gpx4 gene, which encodes for the nuclear, cytosolic, and mitochondrial isoforms of phospholipid-hydroperoxide glutathione peroxidase (PH-GPx/GPx4), the main enzyme protecting cell membranes against lipid peroxidation and capable to reduce oxidized phospholipids in situ. We show here that this novel property of DHA is also significant in the hippocampus of wild-type mice and, to a lesser extent in APP/PS1 transgenic mice, a familial model of Alzheimer's disease. By doing this, DHA stimulates a mechanism to self-protect from oxidative damage even in the neuronal scenario of high aerobic metabolism and in the presence of elevated levels of transition metals, which inevitably favor the generation of reactive oxygen species. Noticeably, DHA also upregulated a Gpx4 CIRT (Cytoplasmic Intron-sequence Retaining Transcripts), a novel Gpx4 splicing variant, harboring part of the first intronic region, which according to the “sentinel RNA hypothesis” would expand the ability of Gpx4 (and DHA) to provide neuronal antioxidant defense independently of conventional nuclear splicing in cellular compartments, like dendritic zones, located away from nuclear compartment. We discuss here, the crucial role of this novel transcriptional regulation triggered by DHA in the context of normal and pathological hippocampal cell.

Oxidative Stress in Alzheimer's Disease: Should We Keep Trying Antioxidant Therapies?

The risk of chronic diseases such as Alzheimer's disease is growing as a result of the continuous increasing average life span of the world population, a syndrome characterized by the presence of intraneural neurofibrillary tangles and senile plaques composed mainly by beta-amyloid protein, changes that may cause a number of progressive disorders in the elderly, causing, in its most advanced stage, difficulty in performing normal daily activities, among other manifestations. Therefore, it is important to understand the underlying pathogenic mechanisms of this syndrome. Nevertheless, despite intensive effort to access the physiopathological pathways of the disease, it remains poorly understood. In that context, some hypotheses have arisen, including the recent oxidative stress hypothesis, theory supported by the involvement of oxidative stress in aging, and the vulnerability of neurons to oxidative attack. In the present revision, oxidative changes and redox mechanisms in Alzheimer's disease will be further stressed, as well as the grounds for antioxidant supplementation as adjuvant therapy for the disease will be addressed.

A neuronal DNA damage response is detected at the earliest stages of Alzheimer's neuropathology and correlates with cognitive impairment in the Medical Research Council's Cognitive Function and Ageing Study ageing brain cohort

AIMS

Population-based studies have shown that approximately 20% of the ageing population (aged 65 years and over) with dementia have little or no classical Alzheimer-type neuropathology. Cumulative DNA damage and a reduced capacity of DNA repair may result in neuronal dysfunction and contribute to cognitive impairment independent of Alzheimer-type pathology in the ageing brain.

METHODS

We investigated expression of the DNA damage response (DDR)-associated molecules γH2AX and DNA-PKcs using immunohistochemistry and western blotting, and senescence-associated β-galactosidase in the frontal association neocortex of cases with low levels of Alzheimer-type pathology (Braak & Braak stage 0-II), and explored their relationship to cognitive impairment in a population-representative sample from the Medical Research Council's Cognitive Function and Ageing Study cohort.

RESULTS

Increases in both γH2AX(+) (r(s)  = -0.36, P = 0.025) and DNA-PKcs(+) (r(s)  = -0.39, P = 0.01) neuronal counts were associated with a lower Mini-Mental State Examination score. Increasing levels of senescence associated-β-gal(+) pyramidal neurones were weakly associated with the total number of DNA-PKcs(+) neurones (P = 0.08), but not with traditional senescence-associated signalling molecules, including p53 and p16.

CONCLUSION

The association between the neuronal DDR and cognitive impairment, independent of AD pathology in the ageing brain, may be suggestive of a causal link via neuronal dysfunction.

WIN 55,212-2, agonist of cannabinoid receptors, prevents amyloid β1-42 effects on astrocytes in primary culture

Alzheimer´s disease (AD), a neurodegenerative illness involving synaptic dysfunction with extracellular accumulation of Aβ_1-42 toxic peptide, glial activation, inflammatory response and oxidative stress, can lead to neuronal death. Endogenous cannabinoid system is implicated in physiological and physiopathological events in central nervous system (CNS), and changes in this system are related to many human diseases, including AD. However, studies on the effects of cannabinoids on astrocytes functions are scarce. In primary cultured astrocytes we studied cellular viability using MTT assay. Inflammatory and oxidative stress mediators were determined by ELISA and Western-blot techniques both in the presence and absence of Aβ_1-42 peptide. Effects of WIN 55,212-2 (a synthetic cannabinoid) on cell viability, inflammatory mediators and oxidative stress were also determined. Aβ_1-42 diminished astrocytes viability, increased TNF-α and IL-1β levels and p-65, COX-2 and iNOS protein expression while decreased PPAR-γ and antioxidant enzyme Cu/Zn SOD. WIN 55,212-2 pretreatment prevents all effects elicited by Aβ_1-42. Furthermore, cannabinoid WIN 55,212-2 also increased cell viability and PPAR-γ expression in control astrocytes. In conclusion cannabinoid WIN 55,212-2 increases cell viability and anti-inflammatory response in cultured astrocytes. Moreover, WIN 55,212-2 increases expression of anti-oxidant Cu/Zn SOD and is able to prevent inflammation induced by Aβ_1-42 in cultured astrocytes. Further studies would be needed to assess the possible beneficial effects of cannabinoids in Alzheimer's disease patients.

Sulforaphane ameliorates neurobehavioral deficits and protects the brain from amyloid β deposits and peroxidation in mice with Alzheimer-like lesions

Alzheimer's disease (AD) is a common neurodegenerative disease in the elderly individuals and its effective therapies are still unavailable. This study was designed to investigate the neuroprotection of sulforaphane (SFN) in AD-lesion mice induced by combined administration of d-galactose and aluminium. Results showed that SFN ameliorated spatial cognitive impairment and locomotor activity decrease in Morris water maze and open field test, respectively. And attenuated numbers of amyloid β (Aβ) plaques in both hippocampus and cerebral cortex of AD-lesion mice were detected by immunohistochemistry. According to spectrophotometry and quantitative reverse-transcriptase polymerase chain reaction results, a significant increase in carbonyl group level and obvious decreases in both activity and messenger RNA expression of glutathione peroxidase were found in brain of AD-lesion mice compared with control, but not in SFN-treated AD-lesion mice. In conclusion, SFN ameliorates neurobehavioral deficits and protects the brain from Aβ deposits and peroxidation in mice with Alzheimer-like lesions, suggesting SFN is likely a potential phytochemical to be used in AD therapeutics.

On the role of 4-hydroxynonenal in health and disease

Polyunsaturated fatty acids are susceptible to peroxidation and they yield various degradation products, including the main α,β-unsaturated hydroxyalkenal, 4-hydroxy-2,3-trans-nonenal (HNE) in oxidative stress. Due to its high reactivity, HNE interacts with various macromolecules of the cell, and this general toxicity clearly contributes to a wide variety of pathological conditions. In addition, growing evidence suggests a more specific function of HNE in electrophilic signaling as a second messenger of oxidative/electrophilic stress. It can induce antioxidant defense mechanisms to restrain its own production and to enhance the cellular protection against oxidative stress. Moreover, HNE-mediated signaling can largely influence the fate of the cell through modulating major cellular processes, such as autophagy, proliferation and apoptosis. This review focuses on the molecular mechanisms underlying the signaling and regulatory functions of HNE. The role of HNE in the pathophysiology of cancer, cardiovascular and neurodegenerative diseases is also discussed.

Oxidative stress, testosterone, and cognition among Caucasian and Mexican-American men with and without Alzheimer's disease

BACKGROUND

The use of testosterone among aging men has been increasing, but results from studies addressing the effectiveness of testosterone replacement therapy have been equivocal.

OBJECTIVE

Given our prior pre-clinical studies that reported a major influence of oxidative stress on testosterone's neuroprotective effects, we investigated whether the negative effects of testosterone on brain function were predicted by oxidative load.

METHODS

In order to test our hypothesis, we determined whether circulating total testosterone and luteinizing hormone correlated with cognition in a subset of the Texas Alzheimer's Research & Care Consortium (TARCC) cohort, consisting of Caucasian (n = 116) and Mexican-American (n = 117) men. We also assessed whether oxidative stress (as indexed by homocysteine levels) modified this relationship between sex hormones and cognition, and whether the levels of two antioxidants, superoxide dismutase-1 and glutathione S-transferase (GST), varied as a function of circulating testosterone.

RESULTS

In a low oxidative stress environment, testosterone was positively associated with the level of the antioxidant, GST, while no deleterious effects on cognitive function were noted. In contrast, under conditions of high oxidative stress (homocysteine levels >12 μmol/L), testosterone and luteinizing hormone were associated with cognitive impairment, but only among Caucasians. The ethnic difference was attributed to significantly higher GST levels among Mexican-Americans.

CONCLUSION

While testosterone may be beneficial under conditions of low oxidative stress, testosterone appears to have negative consequences under conditions of elevated oxidative stress, but only in Caucasians. Mexican-Americans, however, were protected from any deleterious effects of testosterone, potentially due to higher levels of endogenous antioxidant defenses such as GST.

Selenoproteins in nervous system development and function

Selenoproteins are a distinct class of proteins that are characterized by the co-translational incorporation of selenium (Se) in the form of the 21st amino acid selenocysteine. Selenoproteins provide a key defense against oxidative stress, as many of these proteins participate in oxidation-reduction reactions neutralizing reactive oxygen species, where selenocysteine residues act as catalytic sites. Many selenoproteins are highly expressed in the brain, and mouse knockout studies have determined that several are required for normal brain development. In parallel with these laboratory studies, recent reports of rare human cases with mutations in genes involved in selenoprotein biosynthesis have described individuals with an assortment of neurological problems that mirror those detailed in knockout mice. These deficits include impairments in cognition and motor function, seizures, hearing loss, and altered thyroid metabolism. Additionally, due to the fact that oxidative stress is a key feature of neurodegenerative disease, there is considerable interest in the therapeutic potential of selenium supplementation for human neurological disorders. Studies performed in cell culture and rodent models have demonstrated that selenium administration attenuates oxidative stress, prevents neurodegeneration, and counters cell signaling mechanisms known to be dysregulated in certain disease states. However, there is currently no definitive evidence in support of selenium supplementation to prevent and/or treat common neurological conditions in the general population. It appears likely that, in humans, supplementation with selenium may only benefit certain subpopulations, such as those that are either selenium-deficient or possess genetic variants that affect selenium metabolism.

3-Hydroxy-4-pyridinone derivatives as metal ion and amyloid binding agents

Metal ions have been implicated in several neurodegenerative diseases, including Alzheimer's disease, as their dyshomeostasis may lead to production of reactive oxygen species as well as increased toxicity of amyloid protein aggregates. In this work, we present design and synthesis of three novel multifunctional hydroxypyridinone ligands, HL11, HL12, and HL13, bearing benzothiazole and benzoxazole functionalities. We study the ability of these compounds to bind metal ions Cu(II), Zn(II), and Fe(III), as well as their antioxidant activity and cytotoxicity. Additionally, we determine the pro-ligands' (compounds prior to chelation) propensity to target amyloid protein. Through these studies we determine the effect of combining amyloid- and metal-binding functionalities within the HPO scaffold on different aspects of AD pathology.

Role of Notch-1 signaling pathway in PC12 cell apoptosis induced by amyloid beta-peptide (25-35)

Recent studies have demonstrated that Notch-1 expression is increased in the hippocampus of Alzheimer's disease patients. We speculate that Notch-1 signaling may be involved in PC12 cell apoptosis induced by amyloid beta-peptide (25–35) (Aβ_25–35). In the present study, PC12 cells were cultured with different doses (0, 0.1, 1.0, 10 and 100 nmol/L) of N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester, a Notch-1 signaling pathway inhibitor, for 30 minutes. Then cultured cells were induced with Aβ_25–35 for 48 hours. Pretreatment of PC12 cells with high doses of N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (> 10 nmol/L) prolonged the survival of PC12 cells after Aβ_25–35 induction, decreased the expression of apoptosis-related proteins caspase-3, -8, -9, increased the activity of oxidative stress-related superoxide dismutase and catalase, inhibited the production of active oxygen, and reduced nuclear factor kappa B expression. This study indicates that the Notch-1 signaling pathway plays a pivotal role in Aβ_25–35-induced PC12 apoptosis.

Down's syndrome, dementia and macrocytosis

Objective: No definitive peripheral biological marker has yet been found to correlate with Alzheimer's disease (AD). This study investigated the role of macrocytosis as a marker which could significantly improve our understanding of AD in the Down's syndrome (DS) population.

Methods: This study investigated the possible association between raised mean corpuscular volume (MCV) and AD in 150 adults with DS over a five year study period.

Results: A raised MCV is common in the DS population. A statistically significant association between a further elevated MCV and clinically diagnosed AD in adults with DS was found.

Conclusions: The findings suggest that further research into the association between macrocytosis and DS could improve our understanding of the underlying biological mechanisms of AD. The measurement of MCV should be undertaken in all DS individuals with a diagnosis of possible or definite dementia. A significant raised MCV (above 97fl for males and 99fl for females) may further improve the clinical diagnosis. A single MCV measurement, however, cannot be recommended as a diagnostic test for AD in adults with DS.

RCAN1 overexpression exacerbates calcium overloading-induced neuronal apoptosis

Down Syndrome (DS) patients develop characteristic Alzheimer's Disease (AD) neuropathology after their middle age. Prominent neuronal loss has been observed in the cortical regions of AD brains. However, the underlying mechanism leading to this neuronal loss in both DS and AD remains to be elucidated. Calcium overloading and oxidative stress have been implicated in AD pathogenesis. Two major isoforms of regulator of calcineurin 1 (RCAN1), RCAN1.1 and RCAN1.4, are detected in human brains. In this report we defined the transcriptional regulation of RCAN1.1 and RCAN1.4 by two alternative promoters. Calcium overloading upregulated RCAN1.4 expression by activating RCAN1.4 promoter through calcineurin-NFAT signaling pathway, thus forming a negative feedback loop in isoform 4 regulation. Furthermore, RCAN1.4 overexpression exacerbated calcium overloading-induced neuronal apoptosis, which was mediated by caspase-3 apoptotic pathway. Our results suggest that downregulating RCAN1.4 expression in neurons could be beneficial to AD patients.

Oxidative stress in Alzheimer's disease

Oxidative stress plays a significant role in the pathogenesis of Alzheimer's disease (AD), a devastating disease of the elderly. The brain is more vulnerable than other organs to oxidative stress, and most of the components of neurons (lipids, proteins, and nucleic acids) can be oxidized in AD due to mitochondrial dysfunction, increased metal levels, inflammation, and β-amyloid (Aβ) peptides. Oxidative stress participates in the development of AD by promoting Aβ deposition, tau hyperphosphorylation, and the subsequent loss of synapses and neurons. The relationship between oxidative stress and AD suggests that oxidative stress is an essential part of the pathological process, and antioxidants may be useful for AD treatment.

Cocoa powder triggers neuroprotective and preventive effects in a human Alzheimer's disease model by modulating BDNF signaling pathway

The molecular mechanisms linking Aβ to the onset of neurotoxicity are still largely unknown, but several lines of evidence point to reactive oxygen species, which are produced even under the effect of nanomolar concentrations of soluble Aβ-oligomers. The consequent oxidative stress is considered as the mediator of a cascade of degenerative events in many neurological disorders. Epidemiological studies indicate that dietary habits and antioxidants from diet can influence the incidence of neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. In the recent years, a number of reviews have reported on neuroprotective effects of polyphenols in cell and animal models. However, the majority of these studies have focused only on the anti-oxidant properties of these compounds and less on the mechanism/s of action at cellular level. In this work we investigated the effect of cocoa polyphenolic extract on a human AD in vitro model. The results obtained, other than confirming the anti-oxidant properties of cocoa, demonstrate that cocoa polyphenols triggers neuroprotection by activating BDNF survival pathway, both on Aβ plaque treated cells and on Aβ oligomers treated cells, resulting in the counteraction of neurite dystrophy. On the light of the results obtained the use of cocoa powder as preventive agent for neurodegeneration is further supported.

Lycium barbarum polysaccharides prevent memory and neurogenesis impairments in scopolamine-treated rats

Lycium barbarum is used both as a food additive and as a medicinal herb in many countries, and L. barbarum polysaccharides (LBPs), a major cell component, are reported to have a wide range of beneficial effects including neuroprotection, anti-aging and anticancer properties, and immune modulation. The effects of LBPs on neuronal function, neurogenesis, and drug-induced learning and memory deficits have not been assessed. We report the therapeutic effects of LBPs on learning and memory and neurogenesis in scopolamine (SCO)-treated rats. LBPs were administered via gastric perfusion for 2 weeks before the onset of subcutaneous SCO treatment for a further 4 weeks. As expected, SCO impaired performance in novel object and object location recognition tasks, and Morris water maze. However, dual SCO- and LBP-treated rats spent significantly more time exploring the novel object or location in the recognition tasks and had significant shorter escape latency in the water maze. SCO administration led to a decrease in Ki67- or DCX-immunoreactive cells in the dentate gyrus and damage of dendritic development of the new neurons; LBP prevented these SCO-induced reductions in cell proliferation and neuroblast differentiation. LBP also protected SCO-induced loss of neuronal processes in DCX-immunoreactive neurons. Biochemical investigation indicated that LBP decreased the SCO-induced oxidative stress in hippocampus and reversed the ratio Bax/Bcl-2 that exhibited increase after SCO treatment. However, decrease of BDNF and increase of AChE induced by SCO showed no response to LBP administration. These results suggest that LBPs can prevent SCO-induced cognitive and memory deficits and reductions in cell proliferation and neuroblast differentiation. Suppression of oxidative stress and apoptosis may be involved in the above effects of LBPs that may be a promising candidate to restore memory functions and neurogenesis.

Inhibitory Effects of Eucommia ulmoides Oliv. Bark on Scopolamine-Induced Learning and Memory Deficits in Mice

Eucommia ulmoides Oliv. Bark (EUE) is commonly used for the treatment of hypertension, rheumatoid arthritis, lumbago, and ischialgia as well as to promote longevity. In this study, we tested the effects of EUE aqueous extract in graded doses to protect and enhance cognition in scopolamine-induced learning and memory impairments in mice. EUE significantly improved the impairment of short-term or working memory induced by scopolamine in the Y-maze and significantly reversed learning and memory deficits in mice as measured by the passive avoidance and Morris water maze tests. One day after the last trial session of the Morris water maze test (probe trial session), EUE dramatically increased the latency time in the target quadrant in a dose-dependent manner. Furthermore, EUE significantly inhibited acetylcholinesterase (AChE) and thiobarbituric acid reactive substance (TBARS) activities in the hippocampus and frontal cortex in a dose-dependent manner. EUE also markedly increased brain-derived neurotrophic factor (BDNF) and phosphorylation of cAMP element binding protein (CREB) in the hippocampus of scopolamine-induced mice. Based on these findings, we suggest that EUE may be useful for the treatment of cognitive deficits, and that the beneficial effects of EUE are mediated, in part, by cholinergic signaling enhancement and/or protection.

Mitochondrial dysfunction: cause and consequence of Alzheimer's disease

The etiology of common, nonfamiliar late-onset Alzheimer's disease (LOAD) is only partly understood and seems to be extremely complex including many genetic and environmental factors. The most important environmental risk factor to develop LOAD is aging itself. Aging and LOAD are considered to be strongly linked to mitochondrial dysfunction and enhanced oxidative stress. In this review, we focus on the interaction between mitochondrial dysfunction in aging especially on defects of the respiratory chain of the oxidative phosphorylation system resulting in enhanced oxidative stress and the interplay between aging-associated mitochondrial defects and LOAD-associated mitochondrial failure. The deleterious effects of the two hallmarks of LOAD, amyloid beta, and hyperphosphorylated tau, on mitochondrial function, movement, and morphology are described as well as the toxic effects of the most relevant genetic risk factor of LOAD, the apolipoprotein E4 allele. Finally, the review provides an overview about drugs and nutritional ingredients which improve mitochondrial function or/and act as antioxidants and discusses their potential role in the treatment of LOAD.

Neuroprotective and symptomatic effects of targeting group III mGlu receptors in neurodegenerative disease

Neurodegenerative disorders possess common pathological mechanisms, such as protein aggregation, inflammation, oxidative stress (OS) and excitotoxicity, raising the possibility of shared therapeutic targets. As a result of the selective cellular and regional expression of group III metabotropic glutamate (mGlu) receptors, drugs targeting such receptors have demonstrated both neuroprotective properties and symptomatic improvements in several models of neurodegeneration. In recent years, the discovery and development of subtype-selective ligands for the group III mGlu receptors has gained pace, allowing further research into the functions of these receptors and revealing their roles in health and disease. Activation of this class of receptors results in neuroprotection, with a variety of underlying mechanisms implicated. Group III mGlu receptor stimulation prevents excitotoxicity by inhibiting glutamate release from neurons and microglia and increasing glutamate uptake by astrocytes. It also attenuates the neuroinflammatory response by reducing glial reactivity and encourages neurotrophic phenotypes. This article will review the current literature with regard to the neuroprotective and symptomatic effects of group III mGlu receptor activation and discuss their promise as therapeutic targets in neurodegenerative disease. We review the neuroprotective and symptomatic effects of targeting group III mGlu receptors in neurodegenerative disease: Excess extracellular glutamate causes overactivation of NMDA receptors resulting in excitotoxicity. Externalization of phosphatidylserine stimulates phagocytosis of neurons by activated microglia, which contribute to damage through glutamate and pro-inflammatory factor release. Reactive astrocytes produce cytotoxic factors enhancing neuronal cell death. Activation of group III mGlu receptors by glutamate and/or mGlu receptor ligands results in inhibition of glutamate release from presynaptic terminals and microglia, reducing excitotoxicity. Astrocytic glutamate uptake is increased and microglia produce neurotrophic factors.

Nicotinamide treatment reduces the levels of oxidative stress, apoptosis, and PARP-1 activity in Aβ(1-42)-induced rat model of Alzheimer's disease

The underlying mechanisms of Alzheimer's Disease (AD) are still unclear. It is suggested that poly(ADP-ribose) polymerase-1 (PARP-1) overactivation can cause neuroinflammation and cell death. In this study we searched the effects of nicotinamide (NA), endogenous PARP-1 inhibitor, on oxidative stress, apoptosis, and the regulation of PARP-1 and nuclear factor kappa B (NF-κB) in amyloid beta peptide (1-42) (Aβ(1-42))-induced neurodegeneration. Sprague-Dawley rats were divided into four groups as control, Aβ(1-42), Aβ(1-42) + NA(100 and 500 mg/kg). All groups were stereotaxically injected bilaterally into the hippocampus with Aβ(1-42) or saline. After surgery NA administrations were made intraperitoneally (ip) for 7 days. In order to investigate the effects of Aβ(1-42) and NA, protein carbonyls, lipid peroxidation, reactive oxygen species (ROS) production, glutathione (GSH) levels, activities of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase), mitochondrial function, mRNA and protein levels of PARP-1, NF-κB, p53, Bax, and Bcl-2 were measured in specific brain regions such as cortex and hippocampus. Aβ(1-42) treatment only increased the oxidative stress parameters and caused decline in antioxidant enzyme activities, mitochondrial function, and GSH levels. Also, overexpression of PARP-1, NF-κB, p53, Bax, and the decreased levels of Bcl-2 were observed in Aβ(1-42)-treated group. NA treatments against Aβ(1-42)-upregulated Bcl-2 and downregulated PARP-1, NF-κB, p53, and Bax levels. NA treatments also decreased the oxidative stress parameters and elevated antioxidant enzyme activities, GSH levels, and mitochondrial function against Aβ(1-42) treatment. These data suggest that NA may have a therapeutic potential in neurodegenerative processes due to the decreased levels of oxidative stress, apoptosis, and PARP-1 activity.

Oxidative stress and mitochondrial dysfunction in Alzheimer's disease

Alzheimer's disease (AD) exhibits extensive oxidative stress throughout the body, being detected peripherally as well as associated with the vulnerable regions of the brain affected in disease. Abundant evidence not only demonstrates the full spectrum of oxidative damage to neuronal macromolecules, but also reveals the occurrence of oxidative events early in the course of the disease and prior to the formation of the pathology, which support an important role of oxidative stress in AD. As a disease of abnormal aging, AD demonstrates oxidative damage at levels that significantly surpass that of elderly controls, which suggests the involvement of additional factor(s). Structurally and functionally damaged mitochondria, which are more proficient at producing reactive oxygen species but less so in ATP, are also an early and prominent feature of the disease. Since mitochondria are also vulnerable to oxidative stress, it is likely that a vicious downward spiral involving the interactions between mitochondrial dysfunction and oxidative stress contributes to the initiation and/or amplification of reactive oxygen species that is critical to the pathogenesis of AD.

Oxidative stress and the pathogenesis of Alzheimer's disease

Alzheimer's disease (AD) is the most common neurodegenerative disease that causes dementia in the elderly. Patients with AD suffer a gradual deterioration of memory and other cognitive functions, which eventually leads to a complete incapacity and death. A complicated array of molecular events has been implicated in the pathogenesis of AD. The major pathological characteristics of AD brains are the presence of senile plaques, neurofibrillary tangles, and neuronal loss. Growing evidence has demonstrated that oxidative stress is an important factor contributing to the initiation and progression of AD. However, the mechanisms that lead to the disruption of redox balance and the sources of free radicals remain elusive. The excessive reactive oxygen species may be generated from mechanisms such as mitochondria dysfunction and/or aberrant accumulation of transition metals, while the abnormal accumulation of Abeta and tau proteins appears to promote the redox imbalance. The resulted oxidative stress has been implicated in Abeta- or tau-induced neurotoxicity. In addition, evidence has suggested that oxidative stress may augment the production and aggregation of Abeta and facilitate the phosphorylation and polymerization of tau, thus forming a vicious cycle that promotes the initiation and progression of AD.

Glutathione peroxidase contributes with heme oxygenase-1 to redox balance in mouse brain during the course of cerebral malaria

Oxidative stress has been attributed both a key pathogenic and rescuing role in cerebral malaria (CM). In a Plasmodium berghei ANKA murine model of CM, host redox signaling and functioning were examined during the course of neurological damage. Host antioxidant defenses were early altered at the transcriptional level indicated by the gradually diminished expression of superoxide dismutase-1 (sod-1), sod-2, sod-3 and catalase genes. During severe disease, this led to the dysfunctional activity of superoxide dismutase and catalase enzymes in damaged brain regions. Vitagene associated markers (heat shock protein 70 and thioredoxin-1) also showed a decaying expression pattern that paralleled reduced expression of the transcription factors Parkinson disease 7, Forkhead box O 3 and X-box binding protein 1 with a role in preserving brain redox status. However, the oxidative stress markers reactive oxygen/nitrogen species were not accumulated in the brains of CM mice and redox proteomics and immunohistochemistry failed to detect quantitative or qualitative differences in protein carbonylation. Thus, the loss of antioxidant capacity was compensated for in all cerebral regions by progressive upregulation of heme oxygenase-1, and in specific regions by early glutathione peroxidase-1 induction. This study shows for the first time a scenario of cooperative glutathione peroxidase and heme oxygenase-1 upregulation to suppress superoxide dismutase, catalase, heat shock protein-70 and thioredoxin-1 downregulation effects in experimental CM, counteracting oxidative damage and maintaining redox equilibrium. Our findings reconcile the apparent inconsistency between the lack of oxidative metabolite build up and reported protective effect of antioxidant therapy against CM.

Prostaglandin D2 synthase: Apoptotic factor in alzheimer plasma, inducer of reactive oxygen species, inflammatory cytokines and dialysis dementia

BACKGROUND

Apoptosis, reactive oxygen species (ROS) and inflammatory cytokines have all been implicated in the development of Alzheimer's disease (AD).

OBJECTIVES

The present study identifies the apoptotic factor that was responsible for the fourfold increase in apoptotic rates that we previously noted when pig proximal tubule, LLC-PK1, cells were exposed to AD plasma as compared to plasma from normal controls and multi-infarct dementia.

PATIENTS AND METHODS

The apoptotic factor was isolated from AD urine and identified as lipocalin-type prostaglandin D2 synthase (L-PGDS). L-PGDS was found to be the major apoptotic factor in AD plasma as determined by inhibition of apoptosis approximating control levels by the cyclo-oxygenase (COX) 2 inhibitor, NS398, and the antibody to L-PGDS. Blood levels of L-PGDS, however, were not elevated in AD. We now demonstrate a receptor-mediated uptake of L-PGDS in PC12 neuronal cells that was time, dose and temperature-dependent and was saturable by competition with cold L-PGDS and albumin. Further proof of this endocytosis was provided by an electron microscopic study of gold labeled L-PGDS and immunofluorescence with Alexa-labeled L-PGDS.

RESULTS

The recombinant L-PGDS and wild type (WT) L-PGDS increased ROS but only the WTL-PGDS increased IL6 and TNFα, suggesting that differences in glycosylation of L-PGDS in AD was responsible for this discrepancy.

CONCLUSIONS

These data collectively suggest that L-PGDS might play an important role in the development of dementia in patients on dialysis and of AD.

Protective effect of Cnestis ferruginea and its active constituent on scopolamine-induced memory impairment in mice: a behavioral and biochemical study

CONTEXT

Cnestis ferruginea Vahl ex DC (Connaraceae) (CF) is used in traditional African medicine in the management of CNS disorders. The degeneration and dysfunction of cholinergic neurons is closely associated with the cognitive deficits of Alzheimer's disease (AD) and oxidative stress has been implicated in its pathogenesis. However, the influence of C. ferruginea on the cholinergic system and oxidative stress parameters has not been explored.

OBJECTIVE

The present study investigates the effect of methanol root extract of C. ferruginea and its active constituent amentoflavone (CF-2) on memory, oxidative stress and acetylcholinesterase (AChE) activity in scopolamine-induced amnesia.

MATERIALS AND METHODS

Mice were orally treated with CF (25-200 mg/kg), CF-2 (6.25-25 mg/kg) for three days and memory impairment was induced by intraperitoneal injection of scopolamine (3 mg/kg). Memory function was evaluated by passive avoidance and Morris water maze tests. Biochemical parameters of oxidative stress and cholinergic function were estimated in brain after the completion of behavioral studies.

RESULTS

Scopolamine caused memory impairment along with increased AChE activity and oxidative stress in mice brain. Oral administration of CF and CF-2 significantly prevented scopolamine-induced memory impairment, inhibited AChE and enhanced antioxidant enzyme activity in the brain following scopolamine injection as compared to vehicle administration in scopolamine (i.p.)-treated mice that were comparable to the effect of tacrine.

DISCUSSION AND CONCLUSION

The study demonstrated that C. ferruginea and its constituent have significant protective effect against scopolamine-induced memory deficits in mice that can be attributed to their antioxidant and antiAChE activity.

Mitochondrial DNA oxidative damage and repair in aging and Alzheimer's disease

SIGNIFICANCE

Mitochondria are fundamental to the life and proper functioning of cells. These organelles play a key role in energy production, in maintaining homeostatic levels of second messengers (e.g., reactive oxygen species and calcium), and in the coordination of apoptotic cell death. The role of mitochondria in aging and in pathophysiological processes is constantly being unraveled, and their involvement in neurodegenerative processes, such as Alzheimer's disease (AD), is very well known.

RECENT ADVANCES

A considerable amount of evidence points to oxidative damage to mitochondrial DNA (mtDNA) as a determinant event that occurs during aging, which may cause or potentiate mitochondrial dysfunction favoring neurodegenerative events. Concomitantly to reactive oxygen species production, an inefficient mitochondrial base excision repair (BER) machinery has also been pointed to favor the accumulation of oxidized bases in mtDNA during aging and AD progression.

CRITICAL ISSUES

The accumulation of oxidized mtDNA bases during aging increases the risk of sporadic AD, an event that is much less relevant in the familial forms of the disease. This aspect is critical for the interpretation of data arising from tissue of AD patients and animal models of AD, as the major part of animal models rely on mutations in genes associated with familial forms of the disease.

FUTURE DIRECTIONS

Further investigation is important to unveil the role of mtDNA and BER in aging brain and AD in order to design more effective preventive and therapeutic strategies.

Presenilin promotes dietary copper uptake

Dietary copper is essential for multicellular organisms. Copper is redox active and required as a cofactor for enzymes such as the antioxidant Superoxide Dismutase 1 (SOD1). Copper dyshomeostasis has been implicated in Alzheimer's disease. Mutations in the presenilin genes encoding PS1 and PS2 are major causes of early-onset familial Alzheimer's disease. PS1 and PS2 are required for efficient copper uptake in mammalian systems. Here we demonstrate a conserved role for presenilin in dietary copper uptake in the fly Drosophila melanogaster. Ubiquitous RNA interference-mediated knockdown of the single Drosophila presenilin (PSN) gene is lethal. However, PSN knockdown in the midgut produces viable flies. These flies have reduced copper levels and are more tolerant to excess dietary copper. Expression of a copper-responsive EYFP construct was also lower in the midgut of these larvae, indicative of reduced dietary copper uptake. SOD activity was reduced by midgut PSN knockdown, and these flies were sensitive to the superoxide-inducing chemical paraquat. These data support presenilin being needed for dietary copper uptake in the gut and so impacting on SOD activity and tolerance to oxidative stress. These results are consistent with previous studies of mammalian presenilins, supporting a conserved role for these proteins in mediating copper uptake.

Rapid cell death is preceded by amyloid plaque-mediated oxidative stress

Neuronal loss is the ultimate outcome in a variety of neurodegenerative diseases and central nerve system disorders. Understanding the sequelae of events that leads to cell death would provide insight into neuroprotective approaches. We imaged neurons in the living brain of a mouse model of Alzheimer's disease that overexpresses mutant human amyloid precursor protein and presenilin 1 and followed the death of individual neurons in real time. This mouse model exhibited limited neurodegeneration and atrophy, but we were able to identify a small fraction of vulnerable cells that would not have been detectable by using standard approaches. By exploiting a genetically encoded reporter of oxidative stress, we identified susceptible neurons by their increased redox potential. The oxidative stress was most dramatic in neurites near plaques, propagated to cell bodies, and preceded activation of caspases that led to cell death within 24 h. Thus, local oxidative stress surrounding plaques contributes to long-range toxicity and selective neuronal death in Alzheimer's disease.

Decalepis hamiltonii root extract attenuates the age-related decline in the cognitive function in Drosophila melanogaster

Age-associated accumulation of oxidative damage linked to decline of antioxidant defense mechanism, leads to impairment of cognitive function in many organisms. These damages can pass through generations and affect the cognitive quality of progenies. In Drosophila, classical olfactory conditioning results in the formation of different types of memory. Age-related memory impairment (AMI) causes reduction in middle term memory (MTM) and parental senescence causes decline in short-term memory (STM) of the offspring. We have further examined the neuromodulatory effect of Decalepis hamiltonii (Dh) root extract, which is a cocktail of novel antioxidant molecules, on the biochemical oxidative defenses in relation to cognitive ability of the aged flies and their offspring. There is a strong correlation between the age-related decline in the activity of the antioxidant enzymes and the lower cognitive ability of the aged flies and their offspring. Feeding of aged flies in the diet containing 0.1% Dh, markedly enhances the cognitive ability of both aged flies and their offspring which is associated with enhanced antioxidant defenses as evident for the activity of superoxide dismutase (SOD) and catalase. Our findings, for the first time, show that the antioxidant-rich Dh root extract attenuates the age-related decline in cognitive ability of Drosophila, and also shows ameliorative effect on the memory of the offspring.

Neuroprotective effects of inhaled lavender oil on scopolamine-induced dementia via anti-oxidative activities in rats

Lavender is used in traditional medicines in Asia, Europe, ancient Greece and Rome, and was mentioned in the Bible and in ancient Jewish texts. Also, lavender is reported to be an effective medical plant in treating inflammation, depression, stress and headache. The present study was undertaken in order to investigate the antioxidant and antiapoptotic activities of the lavender essential oils from Lavandula angustifolia ssp. angustifolia Mill. and Lavandula hybrida Rev. using superoxide dismutase (SOD), glutathione peroxidase (GPX) and catalase (CAT) specific activities, total content of reduced glutathione (GSH), malondialdehyde (MDA) level (lipid peroxidation) and DNA fragmentation assays in male Wistar rats subjected to scopolamine-induced dementia rat model. In scopolamine-treated rats, lavender essential oils showed potent antioxidant and antiapoptotic activities. Subacute exposures (daily, for 7 continuous days) to lavender oils significantly increased antioxidant enzyme activities (SOD, GPX and CAT), total content of reduced GSH and reduced lipid peroxidation (MDA level) in rat temporal lobe homogenates, suggesting antioxidant potential. Also, DNA cleavage patterns were absent in the lavender groups, suggesting antiapoptotic activity. Taken together, our results suggest that antioxidant and antiapoptotic activities of the lavender essential oils are the major mechanisms for their potent neuroprotective effects against scopolamine-induced oxidative stress in the rat brain.

The possible role of antioxidant vitamin C in Alzheimer's disease treatment and prevention

Oxidative stress is suggested to play a major role in the pathogenesis of Alzheimer's disease (AD). Among the antioxidants, vitamin C has been regarded as the most important one in neural tissue. It also decreases β-amyloid generation and acetylcholinesterase activity and prevents endothelial dysfunction by regulating nitric oxide, a newly discovered factor in the pathogenesis and progression of AD. However, clinical trials using antioxidants, including vitamin C, in patients with AD yielded equivocal results. The current article discusses the relevance of vitamin C in the cellular and molecular pathogenesis of AD and explores its therapeutic potential against this neurodegenerative disorder.

Combretum mucronatum and Capparis thonningii prevent scopolamine-induced memory deficit in mice

CONTEXT

Roots of Combretum mucronatum Schumach. & Thonn. (Combretaceae) and Capparis thonningii Schum. (Capparaceae) are used in southwest Nigeria in the treatment of inflammatory disorders and mental illness.

OBJECTIVE

This study evaluated the antidementic effect of the methanol root extracts of C. mucronatum and C. thonningii on scopolamine (3 mg/kg, i.p.) induced memory impairment in mice.

MATERIALS AND METHODS

The effect of C. mucronatum and C. thonningii (50-200 mg/kg) administered orally for 3 days on memory impairments induced in mice by scopolamine was assessed in the passive avoidance and Morris water maze test and compared with that of tacrine (5 mg/kg, i.p.). The activities of acetylcholinesterase (AchE) and antioxidant enzymes were estimated in the brain after the completion of behavioral studies.

RESULTS

C. mucronatum and C. thonningii root extracts (50-200 mg/kg) reversed scopolamine-induced memory deficit with significant (p < 0.05) increase in transfer latency in passive avoidance test. Similarly, the extracts (200 mg/kg) ameliorated memory deficit as a result of significant (p < 0.001) decrease in escape latency and path length in Morris water maze test. The increased AChE activity induced by scopolamine was significantly (p < 0.05) inhibited by C. mucronatum and C. thonningii (100 and 200 mg/kg) treatment which was similar to the effect of tacrine. Both extracts significantly (p < 0.05) attenuated scopolamine-induced increase in oxidative stress parameters as well as restoration of glutathione activity.

DISCUSSION AND CONCLUSION

C. mucronatum and C. thonningii extracts possess significant anticholinesterase, antioxidant and antidementic properties, which may be useful in the management of Alzheimer's disease.

Copper: effects of deficiency and overload

Copper is an essential trace metal that is required for the catalysis of several important cellular enzymes. However, since an excess of copper can also harm cells due to its potential to catalyze the generation of toxic reactive oxygen species, transport of copper and the cellular copper content are tightly regulated. This chapter summarizes the current knowledge on the importance of copper for cellular processes and on the mechanisms involved in cellular copper uptake, storage and export. In addition, we will give an overview on disturbances of copper homeostasis that are characterized by copper overload or copper deficiency or have been connected with neurodegenerative disorders.

Alzheimer's disease, cholesterol, and statins: the junctions of important metabolic pathways

Recent years have seen a significant increase in published data supporting the positive effects of statins on neurodegenerative diseases, in particular on Alzheimer's disease. Statins show neuroprotective activity by a combination of different cellular and systemic mechanisms that are based on the inhibition of the biosynthesis of cholesterol and isoprenoid by-products. The promising results obtained in vivo and in epidemiological studies are generally not in accordance with those of placebo-controlled randomized clinical trials. Nevertheless, these results make statins valuable assets for disease prevention rather than therapeutic agents for use when disease symptoms are already displayed. Thus, the modulation of midlife cholesterol and/or statin administration prior to the appearance of dementia or cognitive impairment may have a better long-term outcome.

The supplementation of yam powder products can give the nutritional benefits of the antioxidant mineral (cu, zn, mn, fe and se) intakes

Yam has been recognized having the beneficial effects for the prevention of various diseases, such as cancer, immunity, infection and obesity etc. There is increasing consideration to supplement the antioxidant nutrients to make up the lack of the antioxidant nutrient intakes. No study has been reported for the analysis of antioxidant mineral contents and comparison to dietary recommended intake for the sense of health promotion. In our study, we analyzed the contents of antioxidant trace elements (Zn, Mn, Fe, Cu and Se) and Cr contents in cultivated Korean yam powders for evaluation of nutrient intake aspects. We collected the commercial yam powders from six different cultivated areas in the South Korea and measured antioxidant minerals (Zn, Mn, Fe, Cu and Se) and Cr contents using trace element-free plasma spectrometer (ICP) or atomic absorption spectrometer (AAS) after dry-ashing and then wet-acid digestion. The accuracy of mineral analysis method was confirmed by the mineral analysis of standard reference material. Each analyzed element contents in yam were compared to dietary reference intakes of Koreans (KDRIs). The average levels of trace elements (Zn, Mn, Fe, Cu, Se and Cr) in yam powders were 18.3, 11.9, 36.0, 3.7, 1.9 and 1.27 μg/g yam powder, respectively. The intakes of Zn, Fe, Cu and Se of which KDRIs is determined, are accounted as being up to 23.8%, 55.6%, 32.5% and 236% recommended intake (RI) of KDRIs, if daily yam supplementation (50 g) of commercial instruction would be considered. The intake of Mn is about 25% adequate intake (AI) of KDRIs with the daily supplementation of yam powder. Most of mineral intakes from daily yam supplementation were with the range of non-detectable to <10% upper limit (UL) level, which is very much safe. The study results show that daily supplementation of Korean yam power is beneficial to provide the supplemental nutrient intake and also is safe, if the suggested dosage would be considered.

Vitamin E for Alzheimer's dementia and mild cognitive impairment

BACKGROUND

Vitamin E is a dietary compound that functions as an antioxidant scavenging toxic free radicals. Evidence that free radicals may contribute to the pathological processes of cognitive impairment including Alzheimer's disease has led to interest in the use of vitamin E in the treatment of mild cognitive impairment (MCI) and Alzheimer's dementia (AD).

OBJECTIVES

To assess the efficacy of vitamin E in the treatment of AD and prevention of progression of MCI to dementia.

SEARCH METHODS

The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group (ALOIS), The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS as well as many trials databases and grey literature sources were searched on 25 June 2012 using the terms: "Vitamin E", vitamin-E, alpha-tocopherol.

SELECTION CRITERIA

All unconfounded, double-blind, randomised trials in which treatment with vitamin E at any dose was compared with placebo for patients with AD and MCI.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the selection criteria and assessed study quality and extracted and analysed the data. For each outcome measure data were sought on every patient randomised. Where such data were not available an analysis of patients who completed treatment was conducted. It was not possible to pool data between studies owing to a lack of comparable outcome measure.

MAIN RESULTS

Only three studies met the inclusion criteria: two in an AD population and one in an MCI population. In the first of the AD studies (Sano 1996) the authors reported some benefit from vitamin E (2000 IU/day) with fewer participants reaching an end point of death, institutionalisation, change to a Clinical Dementia Rating (CDR) of three, or loss of two basic activities of daily living within two years. Of patients completing treatment, 58% (45/77) on vitamin E compared with 74% (58/78) on placebo reached one of the end points (odds ratio (OR) 0.49; 95% confidence interval (CI) 0.25 to 0.96). The second AD treatment study (Lloret 2009) explored the effects of vitamin E (800 IU/day) on cognitive progression in relation to oxidative stress levels. Patients whose oxidative stress markers were lowered by vitamin E showed no significant difference in the percentage change in Mini-Mental State Examination (MMSE) score, between baseline and six months, compared to the placebo group. The primary aim of the MCI study (Petersen 2005) was to investigate the effect of vitamin E (2000 IU/day) on the time to progression from MCI to possible or probable AD. A total of 214 of the 769 participants progressed to dementia, with 212 being classified as having possible or probable AD. There was no significant difference in the probability of progression from MCI to AD between the vitamin E group and the placebo group (hazard ratio 1.02; 95% CI 0.74 to 1.41; P = 0.91).

AUTHORS' CONCLUSIONS

No convincing evidence that vitamin E is of benefit in the treatment of AD or MCI. Future trials assessing vitamin E treatment in AD should not be restricted to alpha-tocopherol.

Antiamnesic activity of Syzygium cumini against scopolamine induced spatial memory impairments in rats

We evaluated the Antiamnesic effects of methanolic extract of Syzygium cumini (MESC) on spatial memory impairments induced by scopolamine (1 mg/kg, i.p.), a muscarinic antagonist, using the Radial arm maze, Morris water maze, learned helpless ness tests. Effect of MESC was evaluated and compared to standard drug, piracetam (200 mg/kg, i.p.). The MESC significantly (p<0.05) improved the impairment of short term or working memory induced by scopolamine in the Radial arm maze test, and significantly (p<0.05) reversed cognitive impairments in rats as measured by the learned helplessness test. In addition, MESC decreased escape latencies in the Morris water maze test. The activity of acetylcholinesterase in the brain was inhibited significantly (p<0.05) by treatment with MESC to a level similar to that observed in rats treated with piracetam. Moreover treatment with MESC (200 and 400 mg/kg, p.o.) to scopolamine induced rats significantly (p<0.05) decreased TBARS levels which was accompanied by an increase in the activities of SOD and Catalase. MESC has dose dependent effect and 400 mg/kg dose shown more prominent results when compared to 200 mg/kg dose of MESC. These results indicate that MESC may exert anti-amnesic activity via inhibition of acetylcholinesterase and antioxidant mechanisms in the brain.