Scutellarin protects against Aβ-induced learning and memory deficits in rats: involvement of nicotinic acetylcholine receptors and cholinesterase

To examine the protective effects of scutellarin (Scu) on rats with learning and memory deficit induced by β-amyloid peptide (Aβ).Methods:Fifty male Wistar rats were randomly divided into 5 groups: control, sham operation, Aβ, Aβ+Scu, and Aβ+piracetam groups. Aβ25–35 was injected into the lateral ventricle (10 μg each side). Scu (10 mg/2 mL) or piracetam (10 mg/2 mL was intragastrically administered per day for 20 consecutive days following Aβ treatment. Learning and memory was assessed with Morris water maze test. The protein and mRNA levels of nicotinic acetylcholine receptor (nAChR) α4, α7, and β2 subunits in the brain were examined using Western blotting and real-time PCR, respectively. The activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in the brain and plasma were measured using Ellman's colorimetric method.In Aβ group, the escape latency period and first platform cross was significantly increased, and the total number of platform crossings was significantly decreased, as compared with the control and the sham operation groups. Both Scu and piracetam treatment significantly reduced the escape latency period and time to cross platform, and increased the number of platform crosses, but there were no significant differences between Aβ+Scu and Aβ+piracetam groups. In Aβ group, the protein levels of nAChR α4 and α7 subunits in the cerebral cortex were significantly decreased by 42%–47% and 58%–61%, respectively, as compared to the control and the sham operation groups. Scu treatment caused upregulation of α4 and α7 subunit proteins by around 24% and 30%, respectively, as compared to Aβ group, but there were no significant differences between Aβ+Scu and Aβ+piracetam groups. The protein level of nAChR β2 subunit had no significant difference among different groups. The mRNA levels of nAChR α4, α7, and β2 subunits were not significantly changed. In Aβ group, the activities of AChE and BuChE in the brain were significantly increased, but were significantly decreased in the plasma, as compared to the control and the sham operation groups. Scu or piracetam treatment restored the activities in brain and plasma nearly to the levels in the control group.The results suggest that Scu may rescue some of the deleterious effects of Aβ, possibly by stimulating nAChR protein translation and regulating cholinesterase activity.

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title: The Neuroprotective Effects of Phytoestrogens on Amyloid β Protein-induced Toxicity Are Mediated by Abrogating the Activation of Caspase Cascade in Rat Cortical Neurons*
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title: Beta-amyloid (1-42)-induced learning and memory deficits in mice: involvement of oxidative burdens in the hippocampus and cerebral cortex.
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title: Suppressed expression of nicotinic acetylcholine receptors by nanomolar β-amyloid peptides in PC12 cells
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title: Nicotinic Acetylcholine Receptor Signalling: Roles in Alzheimer's Disease and Amyloid Neuroprotection
abstract: Alzheimer's disease (AD), the major contributor to dementia in the elderly, involves accumulation in the brain of extracellular plaques containing the β-amyloid protein (Aβ) and intracellular neurofibrillary tangles of hyperphosphorylated tau protein. AD is also characterized by a loss of neurons, particularly those expressing nicotinic acetylcholine receptors (nAChRs), thereby leading to a reduction in nAChR numbers. The Aβ1–42 protein, which is toxic to neurons, is critical to the onset and progression of AD. The discovery of new drug therapies for AD is likely to be accelerated by an improved understanding of the mechanisms whereby Aβ causes neuronal death. We examine the evidence for a role in Aβ1–42 toxicity of nAChRs; paradoxically, nAChRs can also protect neurons when activated by nicotinic ligands. Aβ peptides and nicotine differentially activate several intracellular signaling pathways, including the phosphatidylinositol 3-kinase/v-akt murine thymoma viral oncogene homolog pathway, the extracellular signal-regulated kinase/mitogen-activated protein kinase, and JAK-2/STAT-3 pathways. These pathways control cell death or survival and the secretion of Aβ peptides. We propose that understanding the differential activation of these pathways by nicotine and/or Aβ1–42 may offer the prospect of new routes to therapy for AD.

title: Nicotinic acetylcholine receptors and nicotinic cholinergic mechanisms of the central nervous system.
abstract: Subtypes of neuronal nicotinic acetylcholine receptors (nAChRs) are constructed from numerous subunit combinations that compose channel-receptor complexes with varied functional and pharmacological characteristics. Structural and functional diversity and the broad presynaptic, postsynaptic, and nonsynaptic locations of nAChRs underlie their mainly modulatory roles throughout the mammalian brain. Presynaptic and preterminal nicotinic receptors enhance neurotransmitter release, postsynaptic nAChRs contribute a small minority of fast excitatory transmission, and nonsynaptic nAChRs modulate many neurotransmitter systems by influencing neuronal excitability. Nicotinic receptors have roles in development and synaptic plasticity, and nicotinic mechanisms participate in learning, memory, and attention. Decline, disruption, or alterations of nicotinic cholinergic mechanisms contribute to dysfunctions such as epilepsy, schizophrenia, Parkinson's disease, autism, dementia with Lewy bodies, Alzheimer's disease, and addiction.

title: Nicotinic acetylcholine receptors of muscles and nerves: comparison of their structures, functional roles, and vulnerability to pathology.
abstract: There are fetal and adult subtypes of muscle nicotinic receptors (AChRs), whose structures and functional roles are reasonably well known. Mutations of their subunits cause congenital myasthenic syndromes. An autoimmune response to them causes myasthenia gravis (MG). The main immunogenic region (MIR) on muscle AChRs accounts for many aspects of the pathological mechanisms by which the autoimmune response impairs neuromuscular transmission. There are many other AChR subtypes, each defined by a different combination of subunits, some of which are transiently expressed in muscle during development, others of which are expressed in keratinocytes, vascular and bronchial epithelia, and other nonneuronal cells, as well as in a wide variety of neurons. Their varied structures and functional roles are much less well known. Mutations in subunits of some of these AChRs have thus far been associated with rare forms of epilepsy and dysautonomia, but other genetic diseases associated with them probably remain to be discovered. Autoimmune responses to some of these subunits are associated with rare dysautonomias and a skin disease. The pathological mechanisms by which these autoimmune responses impair function are much less well known than in the case of MG. AChRs may provide useful drug targets in several neurological diseases. By far, the biggest direct medical impact of AChRs is addiction to tobacco, which is mediated by nicotine acting on a variety of neuronal AChRs.

title: Decreased Protein Levels of Nicotinic Receptor Subunits in the Hippocampus and Temporal Cortex of Patients with Alzheimer’s Disease
abstract: Deficits of cortical nicotinic acetylcholine receptors (nAChRs) have been observed in Alzheimer’s disease (AD) by receptor binding assays. Little is known about the receptor subunit specificity influenced by AD, and it might be of importance for therapeutic strategies. In the present study, the protein levels of nAChR α3, α4, α7, and β2 subunits were investigated using western blot analysis on postmortem brains of patients with AD and age‐matched controls. The results showed that in human postmortem brain samples, bands with molecular masses of 52, 42, and 50 kDa were detected by anti‐α4, anti‐α7, and anti‐β2 antibodies, respectively. When anti‐α3 antibody was used, one major band of 49 kDa and two minor bands of 70 and 38 kDa were detected. In AD patients, as compared with age‐matched controls, the α4 subunit was reduced significantly by ∼35 and 47% in the hippocampus and temporal cortex, respectively. A significant reduction of 25% in the α3 subunit was also observed in the hippocampus and a 29% reduction in the temporal cortex. For the α7 subunit, the protein level was reduced significantly by 36% in the hippocampus of AD patients, but no significant change was detected in the temporal cortex. In neither the hippocampus nor the temporal cortex was a significant difference observed in the β2 subunit between AD patients and controls. These results reveal brain region‐specific changes in the protein levels of the nAChR, α3, α4, and α7 subunits in AD.

title: Selective changes in the levels of nicotinic acetylcholine receptor protein and of corresponding mRNA species in the brains of patients with Parkinson’s disease
abstract: Reductions in the number of neuronal nicotinic acetylcholine receptors (nAChRs) have been shown to occur in connection with Parkinson's disease (PD), but it is still unclear which subtype of this receptor is affected. In the present study we examined various nAChR subtypes employing ligand binding, as well as levels of subunit protein and mRNA in the brains of PD patients and age-matched controls. Binding of [3H]epibatidine and levels of alpha3 mRNA in the caudate nucleus and temporal cortex, but not in the hippocampus were significantly decreased in the PD brain. The level of the alpha3 protein subunit was significantly reduced in all these brain regions but there was no change in the level of alpha4. The level of the beta2 protein subunit in the temporal cortex and hippocampus and the beta2 mRNA in the temporal cortex was lowered. Both the levels of the alpha7 subunit protein and [125I]alpha-bungarotoxin binding were significantly increased in the temporal cortex of PD patients whereas the alpha7 mRNA level was unchanged. These findings reveal selective losses of the alpha3- and beta2-containing nAChRs and an increase in the alpha7 nAChRs that might be related to the pathogenesis of PD.

title: Nicotinic receptor abnormalities in Alzheimer’s disease
abstract: Loss of cortical nicotinic acetylcholine receptors with high affinity for agonists (20-50%) in patients with Alzheimer's disease is a common finding. Recent immunochemical analyses indicate that this deficit is predominantly associated with the loss of alpha4 subunits (30-50%), although modest reductions of alpha3 may occur in some individuals (25-29%). No reduction of beta2 subunit protein expression or levels of alpha3 and alpha4 messenger RNA has been reported. Decline in cortical [(125)I]alpha-bungarotoxin binding and alpha7 protein expression does not appear to be as extensive or widespread as the loss of alpha4 (0-40%), with no reduction in messenger RNA expression. In the thalamus, there was a trend for reduced [(3)H]nicotine binding in the majority of nuclei (0-20%) in Alzheimer's disease; however, there was a significant decline in [(125)I]alpha-bungarotoxin binding in the reticular nucleus. In the striatum [(3)H]nicotine binding was reduced in Alzheimer's disease, and although neuroleptic medication accentuated this change, it occurred in those free of neuroleptics. Changes in nicotinic acetylcholine receptors in Alzheimer's disease are distinct from those in normal aging and are likely to contribute to clinical features and possibly neuropathology.

title: The Rat Brain in Stereotaxic Coordinates

title: Decreased nicotinic receptors and cognitive deficit in rats intracerebroventricularly injected with beta‐amyloid peptide(1‐42) and fed a high‐cholesterol diet
abstract: To investigate whether the changes in nicotinic receptors (nAChRs) and in learning and memory associated with Alzheimer's disease (AD) are influenced by both β‐amyloid peptide (Aβ) and cholesterol in vivo, we examined the effects of intracerebroventricular injection of Aβ1–42 and/or a high‐cholesterol diet on brain levels ofnAChRs and learning and memory in rats. The levels of nAChR subunit proteins and the corresponding mRNA were measured by Western blotting and RT‐PCR, respectively; and learning and memory were evaluated with the Morris Water Maze examination. Injection of Aβ1–42 resulted in deposition of this peptide, activation of astrocytes, decreased levels of the α7 and α4 protein subunits of the nAChR, and elevated expression of α7 mRNA, as well as impaired learning and spatial memory. A high‐cholesterol diet activated astrocytes and, more importantly, potentiated the toxic effects of Aβ on nAChR subunit levels and on learning and memory. These findings may be highly relevant to the mechanisms underlying the cognitive deficits associated with AD.

title: Amyloid precursor protein gene mutated at Swedish 670/671 sites in vitro induces changed expression of nicotinic acetylcholine receptors and neurotoxicity
abstract: In order to investigate the influence of amyloid precursor protein (APP) over-expression on the levels of nicotinic acetylcholine receptors (nAChRs), the pCDNA 3.0 carrying the Swedish 670/671 APP double mutation (APP(SWE)) gene was transfected into human neuroblastoma (SH-SY5Y) cells and primary culture of rat hippocampal neurons. The mRNA level of APP, and nAChR α3, α4 and α7 subunits were detected by real-time PCR, and their corresponding proteins as well as α-secreted APP (αAPPs) by Western blotting. [3H]Epibatidine binding sites were measured by the receptor binding assay. The results showed that significantly concomitant increases in mRNA and protein levels of SH-SY5Y cells and primary cultured neurons transfected with APP(SWE) were observed. Interestingly, a decreased αAPPs level was detected in both cells treated with APP(SWE) transfection. In addition, decreases in mRNA and protein levels of α3 nAChR subunit in SH-SY5Y cells or α4 subunit in primary cultured neurons with APP(SWE) transfection were observed. For α7 nAChR, the increased protein and mRNA levels were found in SH-SY5Y cells and primary cultured neurons with APP(SWE) transfection. The number of cholinergic receptor binding site of [3H]epibatidine was decreased in the SH-SY5Y cells transfected with APP(SWE). Elevations in the activities of AChE and BuChE and in the level of lipid peroxidation were detected in both types of cultured cells transfected with APP(SWE). These results indicated that the over-expression of APP(SWE) gene can influence the expression of nAChRs and resulted in neurotoxicity, in which this process might play an important role in the pathogenesis of Alzheimer's disease.

title: A new and rapid colorimetric determination of acetylcholinesterase activity.
abstract: A photometric method for determining acetylcholinesterase activity of tissue extracts, homogenates, cell suspensions, etc., has been described. The enzyme activity is measured by following the increase of yellow color produced from thiocholine when it reacts with dithiobisnitrobenzoate ion. It is based on coupling of these reactions: The latter reaction is rapid and the assay is sensitive (i.e. a 10 μ1 sample of blood is adequate). The use of a recorder has been most helpful, but is not essential. The method has been used to study the enzyme in human erythrocytes and homogenates of rat brain, kidney, lungs, liver and muscle tissue. Kinetic constants determined by this system for erythrocyte eholinesterase are presented. The data obtained with acetylthiocholine as substrate are similar to those with acetylcholine.

title: Alzheimer's disease and acetylcholine receptors.
abstract: Cholinergic abnormalities, alongside senile plaques, neurofibrillary tangles, and extensive neuronal loss, are the major characteristics in Alzheimer's disease (AD). Both nicotinic and muscarinic acetylcholine receptors are decreased in AD, and it has been shown that the reduction in the number of acetylcholine receptors precedes other pathologic changes. Anti-cholinergic drugs induce amnesia, which can be reversed by withdrawal of the medication. Inhibition of the down-regulation of acetylcholine is, therefore, a strategy for the treatment of AD because it could augment acetylcholine levels within synaptic clefts. In this context, acetylcholinesterase inhibitors, which improve cognitive functions, are currently approved for the treatment of AD. Stimulation of acetylcholine receptors, nicotinic or muscarinic, is another strategy; some drugs are currently under investigation, and reported to be effective. In addition, nicotinic stimulation exerts a neuroprotective effect, and reduces the amyloid burden. Cholinergic therapy may counter the symptoms and progress of AD.

title: Acetylcholinesterase and butyrylcholinesterase--important enzymes of human body.
abstract: The serine hydrolases and proteases are a ubiquitous group of enzymes that is fundamental to many critical life-functions. Human tissues have two distinct cholinesterase activities: acetylcholinesterase and butyrylcholinesterase. Acetylcholinesterase functions in the transmission of nerve impulses, whereas the physiological function of butyrylcholinesterase remains unknown. Acetylcholinesterase is one of the crucial enzymes in the central and peripheral nerve system. Organophosphates and carbamates are potent inhibitors of serine hydrolases and well suited probes for investigating the chemical reaction mechanism of the inhibition. Understanding the enzyme's chemistry is essential in preventing and/or treating organophosphate and carbamate poisoning as well as designing new medicaments for cholinergic-related diseases like as Alzheimer's disease.

title: Cholinesterases within neurofibrillary tangles related to age and Alzheimer's disease
abstract: Enzyme histochemistry showed that a substantial number of cortical neurofibrillary tangles contain acetylcholinesterase and butyrylcholinesterase activities in patients with Alzheimer's disease and in nondemented aged individuals. In some areas of the brain, tangles containing each of these two enzymes were differentially distributed. In other areas, there was a very close overlap between the two types of cholinesterase.

title: Senile plaques: staining for acetylcholinesterase and A4 protein: a comparative study in the hippocampus and entorhinal cortex
abstract: SummaryIn 20 unselected autopsy cases tissue blocks from the hippocampus with adjacent entorhinal cortex and neocortex were stained for acetylcholinesterase (AChE). From five brains shown to have large numbers of senile plaques tissue, adjacent to that taken for AChE tissue blocks, was embedded in paraffin and sections were immunostained for the A4 protein. The morphological aspects were compared. Equivalent types of plaques and plaque-like structures were observed in the A4- and ACHE-stained sections. On selected tissue blocks from patients with many senile plaques two immediately adjacent cryostat sections were stained, one for AChE and one for A4 protein. The same individual plaques could be identified on the two sections. These findings suggest that high AChE activity is intimately associated with the process of A4 protein formation and accumulation in plaques and that this association already occurs at a very carly stage of plaque formation.

title: Therapies for Alzheimer's disease
abstract: Alzheimer’s disease (AD) is a devastating neurological disorder that affects more than 37 million people worldwide1. The economic burden of AD is massive; in the United States alone, the estimated direct and indirect annual cost of patient care is at least US$100 billion. However, the number of therapeutic options for AD remains severely limited. Currently marketed drugs for AD do not prevent or reverse this disease and are approved only for the management of symptoms. Driven by the clear unmet medical need and a better understanding of the biology and pathophysiology of AD, the number of drugs in development for this indication has increased dramatically in recent years.

title: Plants used in Chinese and Indian traditional medicine for improvement of memory and cognitive function
abstract: In traditional practices of Ayurvedic and Chinese medicine, numerous plants have been used to treat cognitive disorders, including neurodegenerative diseases such as Alzheimer's disease (AD). An ethnopharmacological approach has provided leads to identifying potential new drugs from plant sources, including those for cognitive disorders. Many drugs currently available in Western medicine were originally isolated from plants, or are derived from templates of compounds isolated from plants. Some anticholinesterase (anti-ChE) alkaloids isolated from plants have been investigated for their potential in the treatment of AD, and are now in clinical use. Galantamine, isolated from several plants including Lycoris radiata Herb., which was used in traditional Chinese medicine (TCM), is licensed in the United Kingdom for the treatment of mild to moderate AD. Various other plant species have shown pharmacological activities relevant to the treatment of cognitive disorders, indicating potential for therapeutic use in disorders such as AD. This article reviews some of the plants and their active constituents that have been used in traditional Ayurvedic medicine and TCM for their reputed cognitive-enhancing or antiageing effects. Plants and their constituents with pharmacological activities that may be relevant for the treatment of cognitive disorders, including enhancement of cholinergic function in the central nervous system (CNS), anti-inflammatory and antioxidant activities, are discussed.

title: Breviscapine improves functions of spatial learning and memory of focal cerebral ischemia rats.
abstract: To investigate the effects of breviscapine on the functions of spatial learning and memory of focal cerebral ischemia rats.



Rots withl the left middle cerebral artery occluded were made by an intraluminal filament. Then breviscapine (20 mg/kg,40 mg/kg) in experimental group and 10% glucose in control group were administered intraperitoneally once a day for 2 weeks, and the Morris water maze tasks were carried out for 5 days.



Compared with sham-operation group,the animals of ischemia-control group exhibited seriously impaired spatial learning and memory in both place navigation test and spatial probe test. In the place navigation test, the mean value of escape latency in breviscapine group was significantly shorter than that in ischemia control group (P < 0.01 for lower-dose and P < 0.05 for higher-dose breviscapine group, respectively). In the spatial probe test,compared with sham-operation (P < 0.01) and breviscapine group (P < 0.01), the rats of ischemia-control group spent more time in the no-former platform quadrant, and showed reduced frequency of crossing former platform site significantly. The numbers of neurons with Nissl staining and choline acetyltransferase (ChAT) immunopositive neurons in ipssilateral cortex in the breviscapine group were significantly more than those in the ischemia-control group (P < 0.01). In hippocampus, the numbers of neurons with Nissl staining and ChAT immunopositive neurons in the stratum pyramidale of CA area were similar among the groups.



These results indicate that breviscapine can improve the functions of spatial learning and memory of focal cerebral ischemia rats and the protection against the loss of ChAT immunopositive neuron in new cortex may be involved in its mechanisms.

title: Protective effects of breviscapine on ischemic vascular dementia in rats.
abstract: Breviscapine, a traditional Chinese medicine, is extensively used in clinic to treat cardiovascular diseases and cerebrovascular injury. In this study, we demonstrated the effects of breviscapine on vascular dementia (VD) rats, which were mimicked by permanent occlusion of bilateral common carotid arteries. Breviscapine (2 mg/kg for 14 d) improved the performance of learning and memory of VD rats in Morris water maze, decreased the level of lipid peroxidation and free radicals, and attenuated the pathological alterations, such as nuclear shrink, cellular edema and irregular arrangement of pyramidal layer in the hippocampal CA(1) area. In vitro experiment, breviscapine (50 microg/l) protected cortical neuron from injury and decreased intracellular calcium overloading induced by H2O2 (10 mM). The results suggest that breviscapine has therapeutic effect on cerebral ischemia and vascular dementia.

title: Protective effects of scutellarin on superoxide-induced oxidative stress in rat cortical synaptosomes.
abstract: To evaluate the effects of scutellarin on superoxide-induced oxidative stress in rat cortical synaptosomes.



Oxidative damage model was established by incubation with xanthine (0.3 mmol/L) and xanthine oxidase (0.02 U) at 37 degree for 30 min. The extent of membrane oxidation was assessed by malondialdehyde (MDA). Membrane fluidity was measured by fluorescence anisotropy (polarization) of the lipophilic probe 1,6-diphenyl-1,3,5-hexatriene (DPH). Intracellular Ca2+ concentration([Ca2+]i) was measured by fluorescent spectrophotometry. Fura 2-AM was used as an indicator for [Ca2+]i. Na+/K+-ATPase activity assay was based on the amount of inorganic phosphate (Pi) released during an enzymatic hydrolysis of ATP.



Synaptosomes exposed to superoxide significantly elevated the levels of malondialdehyde (MDA) and [Ca2+]i compared with those in normal group. These changes were accompanied by the decrease in membrane fluidity and Na+/K+-ATPase activity. Pretreatment with scutellarin (25-100 micromol/L) significantly ameliorated the oxidative damage of synaptosomes by reducing MDA levels and [Ca2+]i, up-regulating membrane fluidity and restoring Na+/K+-ATPase activity.



Scutellarin exerts a potent protective effect against oxidative damage in synaptosomes induced by superoxide.

title: Effects of scutellarin on PKCγ in PC12 cell injury induced by oxygen and glucose deprivation
abstract: To evaluate the neuroprotective effect and mechanisms of scutellarin (Scu) against PC12 cell injury after oxygen and glucose deprivation followed by reperfusion (OGD-Undifferentiated rat pheochromocytoma PC12 cells, exposed to oxygen and glucose deprivation followed by reperfusion (OGD-Rep), used as an in vitro model of ischemia/reperfusion. Cell survival was evaluated by diphenyltetrazolium bromide (MTT) assay and the amount of LDH release was determined using assay kits. Scu inhibits the increase of [Ca2+]i and the activation of PKCγ, exerting protective effects against PC12 cell injury induced by OGD-Rep.

title: Protection against hydrogen peroxide-induced cytotoxicity in PC12 cells by scutellarin.
abstract: The present study investigated the protective actions of the antioxidant scutellarin against the cytotoxicity produced by exposure to H2O2 in PC12 cells. This was done by assaying for MTT (3,(4,5-dimethylthiazole-2-yl)2,5-diphenyl-tetrazolium bromide) reduction and lactate dehydrogenase (LDH) release. Reactive oxygen species (ROS) and Ca2+ in cells were evaluated by fluorescent microplate reader using DCFH and Fura 2-AM, respectively, as probes. Lipid peroxidation was quantified using thiobarbituric acid-reactive substances (TBARS). Mitochondrial membrane potential (MMP) was assessed by the retention of rhodamine123 (Rh123), a specific fluorescent cationic dye that is readily sequestered by active mitochondria, depending on their transmembrane potential. The DNA content and percentage of apoptosis were monitored with flow cytometry. Vitamin E, a potent antioxidant, was employed as a comparative agent. Preincubation of PC12 cells with scutellarin prevented cytotoxicity induced by H2O2. Intracellular accumulation of ROS, Ca2+ and products of lipid peroxidation, resulting from H2O2 were significantly reduced by scutellarin. Incubation of cells with H2O2 caused a marked decrease in MMP, which was significantly inhibited by scutellarin. PC12 cells treated with H2O2 underwent apoptotic death as determined by flow cytometric assay. The percentage of this H2O2-induced apoptosis in the cells was decreased in the presence of different concentrations of scutellarin. Scutellarin exhibited significantly higher potency compared to the antioxidant vitamin E. The present findings showed that scutellarin attenuated H2O2-induced cytotoxicity, intracellular accumulation of ROS and Ca2+, lipid peroxidation, and loss of MMP and DNA, which may represent the cellular mechanisms for its neuroprotective action.

title: Long‐term and high‐dose piracetam treatment of Alzheimer's disease
abstract: Preclinical research suggests that piracetam (a nootropic drug) may improve cognitive functions, but previous studies have failed to demonstrate a clear benefit for the treatment of Alzheimer's disease (AD). We report a 1-year, double-blind, placebo-controlled, parallel-group study with a high dose of piracetam (8 g/d per os) in 33 ambulant patients with early probable AD. Thirty subjects completed the 1-year study. No improvement occurred in either group, but our results support the hypothesis that long-term administration of high doses of piracetam might slow the progression of cognitive deterioration in patients with AD. The most significant differences concerned the recall of pictures series and recent incident and remote memory. The drug was well-tolerated.