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1.  A randomized phase I study of methanesulfonyl fluoride, an irreversible cholinesterase inhibitor, for the treatment of Alzheimer's disease 
To ascertain the tolerability profile of single and repeated oral doses of methanesulfonyl fluoride (MSF, SNX-001) in healthy aged subjects, and to determine the degree of erythrocyte acetylcholinesterase (AChE) inhibition induced by MSF after single and repeated oral doses.
To calculate properly the kinetics and the duration of AChE inhibition, the effects of MSF were also studied in rodents. These experiments suggested that MSF administered three times per week should provide safe and efficacious AChE inhibition. In a randomized placebo-controlled phase I study, 3.6 mg, 7.2 mg or 10.8 mg MSF were then orally administered to 27 consenting healthy volunteers (aged 50 to 72 years). After a single dose phase and a 1 week wash-out period, the subjects received the same doses three times per week for 2 weeks.
Twenty-two out of the 27 subjects completed the study. Four patients withdrew due to adverse events (AEs) and one for non-compliance. Erythrocyte AChE was inhibited by a total of 33%, 46%, and 62% after 2 weeks of 3.6 mg, 7.2 mg and 10.8 mg MSF, respectively. No serious AEs occurred. The most frequent AEs were headache (27%), nausea (11%) and diarrhoea (8%).
MSF proved to be well tolerated even with repeated oral dosing. It is estimated that MSF provided a degree of AChE inhibition that should effectively enhance memory. This molecule deserves to be tested for efficacy in a pilot randomized controlled study in patients with Alzheimer's disease.
PMCID: PMC3635594  PMID: 23116458
acetylcholinesterase; Alzheimer's disease; cholinesterase inhibition; methanesulfonyl fluoride; MSF; phase I human study
2.  A randomized phase I study of methanesulfonyl fluoride, an irreversible cholinesterase inhibitor, for the treatment of Alzheimer's disease 
To ascertain the tolerability profile of single and repeated oral doses of methanesulfonyl fluoride (MSF, SNX-001) in healthy aged subjects, and to determine the degree of erythrocyte acetylcholinesterase (AChE) inhibition induced by MSF after single and repeated oral doses.
To calculate properly the kinetics and the duration of AChE inhibition, the effects of MSF were also studied in rodents. These experiments suggested that MSF administered three times per week should provide safe and efficacious AChE inhibition. In a randomized placebo-controlled phase I study, 3.6 mg, 7.2 mg or 10.8 mg MSF were then orally administered to 27 consenting healthy volunteers (aged 50 to 72 years). After a single dose phase and a 1 week wash-out period, the subjects received the same doses three times per week for 2 weeks.
Twenty-two out of the 27 subjects completed the study. Four patients withdrew due to adverse events (AEs) and one for non-compliance. Erythrocyte AChE was inhibited by a total of 33%, 46%, and 62% after 2 weeks of 3.6 mg, 7.2 mg and 10.8 mg MSF, respectively. No serious AEs occurred. The most frequent AEs were headache (27%), nausea (11%) and diarrhoea (8%).
MSF proved to be well tolerated even with repeated oral dosing. It is estimated that MSF provided a degree of AChE inhibition that should effectively enhance memory. This molecule deserves to be tested for efficacy in a pilot randomized controlled study in patients with Alzheimer's disease.
PMCID: PMC3635594  PMID: 23116458
acetylcholinesterase; Alzheimer's disease; cholinesterase inhibition; methanesulfonyl fluoride; MSF; phase I human study
3.  In utero methanesulfonyl fluoride differentially affects learning and maze performance in the absence of long-lasting cholinergic changes in the adult rat 
There is increasing evidence that acetylcholinesterase (AChE) may have various specific developmental roles in brain development. Nevertheless, specific effects of AChE inhibition during early brain development have not been adequately described. Therefore, methanesulfonyl fluoride (MSF), an irreversible AChE inhibitor that shows high selectivity for the CNS was used to produce AChE inhibition in utero to study subsequent adult behaviors, sleep, and cholinergic markers. Rats exposed to MSF in utero showed a deficit in spatial learning tasks using appetitive motivation but, surprisingly, they performed equally well or better than controls when aversive motivation was used. One hypothesis was that MSF treatment in utero affected the response to stress. Tests of anxiety however showed no differences in basal levels of anxiety. Studies of sleep behavior, however, indicated a higher level of REM sleep which is only seen during the light phase of male rats exposed to MSF in utero as compared to controls. No differences in cholinergic markers in the brains of adults were found except that females exposed to MSF in utero had a higher level of ChAT activity in the synaptosomal fraction of the hippocampus. Even so, whether cholinergic alterations accompany the in utero MSF exposure remains to be determined. The failure to find widespread changes in cholinergic markers in the adult brains suggests changes in behaviors should be further investigated by testing the participation of postsynaptic mechanisms, measuring of cholinergic markers during earlier development periods and the possible participation of other neurotransmitter systems to clearly reveal the role of the cholinergic system following in utero MSF exposure.
PMCID: PMC2278117  PMID: 17920111
Acetylcholine; Acetylcholinesterase; Methanesulfonyl fluoride (msf); Development; Choline acetyltransferase; Choline uptake; Sleep
4.  Synthesis, docking and acetylcholinesterase inhibitory assessment of 2-(2-(4-Benzylpiperazin-1-yl)ethyl)isoindoline-1,3-dione derivatives with potential anti-Alzheimer effects 
Alzheimer’s disease (AD) as neurodegenerative disorder, is the most common form of dementia accounting for about 50-60% of the overall cases of dementia among persons over 65 years of age. Low acetylcholine (ACh) concentration in hippocampus and cortex areas of the brain is one of the main reasons for this disease. In recent years, acetylcholinesterase (AChE) inhibitors like donepezil with prevention of acetylcholine hydrolysis can enhance the duration of action of acetylcholine in synaptic cleft and improve the dementia associated with Alzheimer’s disease.
Design, synthesis and assessment of anticholinesterase activity of 2-(2-(4-Benzylpiperazin-1-yl)ethyl)isoindoline-1,3-dione derivatives showed prepared compounds can function as potential acetylcholinesterase inhibitor. Among 12 synthesized derivatives, compound 4a with ortho chlorine moiety as electron withdrawing group exhibited the highest potency in these series (IC50 = 0.91 ± 0.045 μM) compared to donepezil (IC50 = 0.14 ± 0.03 μM). The results of the enzyme inhibition test (Ellman test) showed that electron withdrawing groups like Cl, F and NO2 can render the best effect at position ortho and para of the phenyl ring. But compound 4g with methoxy group at position 3(meta) afforded a favorable potency (IC50 = 5.5 ± 0.7 μM). Furthermore, docking study confirmed a same binding mode like donepezil for compound 4a.
Synthesized compounds 4a-4l could be proposed as potential anticholinesterase agents.
PMCID: PMC3704662  PMID: 23758724
Synthesis; Phthalimide; Acetylcholinesterase (AChE); Anti-Alzheimer; Ellman test; Docking
5.  Donepezil in Alzheimer’s disease: an evidence-based review of its impact on clinical and economic outcomes 
Core Evidence  2006;1(3):195-219.
Donepezil is indicated for the symptomatic treatment of mild to moderate Alzheimer’s disease. It is a specific and reversible inhibitor of acetylcholinesterase (AChE); by increasing levels of available acetylcholine, donepezil may compensate for the loss of functioning cholinergic brain cells.
This review evaluates the clinical impact of donepezil by assessing randomized controlled and open-label naturalistic trials, as well as observational studies. A broad perspective is gained of its effectiveness on various outcomes.
Evidence review:
There is strong evidence that donepezil has efficacy against the three major domains of Alzheimer’s disease symptoms, namely functional ability, behavior, and cognition. The strongest evidence is for improvement or less deterioration in global outcomes and cognition in the short to medium term. There is limited evidence that improved global outcomes are maintained in the long term and clear evidence to support long-term maintenance of cognitive benefits. Also, donepezil appears to maintain function in the long term and there is some level 1 and 2 evidence of improved or limited deterioration in behavior or mood in the short to medium term. Despite donepezil’s effects on major symptoms of Alzheimer’s disease, its impact on patients’ quality of life has not been consistently demonstrated, perhaps reflecting the difficulty of assessing this aspect in this patient population. Donepezil may also lessen caregiver burden. Donepezil has some effect on markers of brain function, but more data are needed to confirm a neuroprotective effect. There is limited and conflicting evidence that long-term donepezil treatment delays time to institutionalization. There is some evidence that donepezil may be cost effective, especially when unpaid caregiver costs are considered. Donepezil is generally safe and well tolerated.
Clinical value:
AChE inhibitors are the only agents recommended for the treatment of cognitive decline in patients with mild to moderate Alzheimer’s disease. Donepezil is more effective than placebo and is well tolerated in improving the major symptoms of this disease. Improvements are usually modest, although stabilization of cognitive and functional symptoms with donepezil can also be considered an important clinical outcome. Donepezil may lessen caregiver burden. Donepezil may also be cost effective, especially when unpaid caregiver costs are considered. More data are required from randomized controlled trials with long-term follow-up to confirm its cost effectiveness and impact on quality of life, disease progression, and time to institutionalization.
PMCID: PMC3321665  PMID: 22500154
acetylcholinesterase (AChE) inhibitor; Alzheimer’s disease; dementia; donepezil; evidence; outcomes
Chemico-biological interactions  2012;203(1):221-225.
The anticholinesterase (antiChE) organophosphorus (OP) and methylcarbamate (MC) insecticides have been used very effectively as contact and systemic plant protectants for seven decades. About 90 of these compounds are still in use – the largest number for any insecticide chemotype or mode of action. In both insects and mammals, AChE inhibition and acetylcholine accumulation leads to excitation and death. The cholinergic system of insects is located centrally (where it is protected from ionized OPs and MCs) but not at the neuromuscular junction. Structural differences between insect and mammalian AChE are also evident in their genomics, amino acid sequences and active site conformations. Species selectivity is determined in part by inhibitor and target site specificity. Pest population selection with OPs and MCs has resulted in a multitude of modified AChEs of altered inhibitor specificity some conferring insecticide resistance and others enhancing sensitivity. Much of the success of antiChE insecticides results from a suitable balance of bioactivation and detoxification by families of CYP450 oxidases, hydrolases, glutathione S-transferases and others. Known inhibitors for these enzymes block detoxification and enhance potency which is particularly important in resistant strains. The current market for OPs and MCs of 19% of worldwide insecticide sales is only half of that of 10 years ago for several reasons: there have been no major new compounds for 30 years; resistance has eroded their effectiveness; human toxicity problems are still encountered; the patents have expired reducing the incentive to update registration packages; alternative chemotypes or control methods have been developed. Despite this decline, they still play a major role in pest control and the increasing knowledge on their target sites and metabolism may make it possible to redesign the inhibitors for insensitive AChEs and to target new sites in the cholinergic system. The OPs and MCs are down but not out.
PMCID: PMC3572339  PMID: 22926007
Acetylcholinesterase; Anticholinesterase; Cytochrome; P450 Insecticide; Resistance; Selective toxicity
7.  Acute but not chronic Donepezil administration increases muscarinic receptor-mediated brain signaling involving arachidonic acid in unanesthetized rats 
Donepezil, an acetylcholinesterase (AChE) inhibitor that is used to treat patients with Alzheimer’s disease, is thought to act by increasing brain extracellular acetylcholine (ACh), and thus ACh binding to cholinergic receptors. Cholinergic muscarinic receptors may be coupled to cytosolic phospholipase A2 (cPLA2) activation and arachidonic acid (AA) release from synaptic membrane phospholipid, and this activation can be imaged in rodents as an AA incorporation coefficient k*, using quantitative autoradiography. To examine acute and chronic effects of Donepezil on the AA signal, k* for AA was measured with quantitative autoradiography in 81 brain regions of unanesthetized rats. Twenty min after a single oral dose (3.0 mg/kg) of Donepezil compared with saline, k* was increased significantly in 37 brain regions, whereas k* did not differ from control 7 h afterwards or following chronic (21 days) of Donepezil. Pretreatment with atropine prevented the 20-min increments in k* following Donepezil. Donepezil also increased the brain ACh concentration and reduced brain AChE activity, but did not change cPLA2 activity, regardless of administration regimen. These results show that Donepezil acutely increases the brain AA signal that is mediated by ACh acting at muscarinic receptors, but that this signal is rapidly desensitized despite continued elevated brain ACh concentration. In contrast, the AA signal in response to arecoline was not altered following Donepezil.
PMCID: PMC2790024  PMID: 19363262
Donepezil; muscarinic receptors; acetylcholine; arachidonic acid; phospholipase A2; acetylcholinesterase; anticholinesterase; Alzheimer disease; imaging; brain; desensitization
8.  Positive allosteric modulator of alpha 7 nicotinic-acetylcholine receptors, PNU-120596 augments the effects of donepezil on learning and memory in aged rodents and non-human primates 
Neuropharmacology  2012;67C:201-212.
The development of novel therapeutic agents for disorders of cognition such as Alzheimer’s disease (AD) is of paramount importance given the ever-increasing elderly population, however; there is also considerable interest in any strategy that might enhance the clinical efficacy of currently available treatments. The purpose of this study was to evaluate an adjunctive treatment strategy to memory enhancement, namely combining the commonly prescribed acetylcholinesterase inhibitor (AChEI) donepezil, with a positive allosteric modulator (PAM) of α7 nicotinic-acetylcholine receptors (α7-nAChRs), PNU-120596. The treatment strategy was evaluated in a (non-spatial) spontaneous novel object recognition (NOR) task in young rats; a water maze spatial learning and recall procedure in aged, cognitively-impaired rats, and a delayed match to sample (working/short term memory) task in aged rhesus monkeys. In all three experiments a similar drug response was observed, namely that donepezil administered alone improved task performance in a dose-dependent manner; that PNU-120596 administered alone was without significant effect, but that the combination of PNU-120596 with a subthreshold dose of donepezil was effective. The positive effect of the drug combination appeared to be α7-nAChR mediated given that it was blocked in the NOR task by the selective α7-nAChR antagonist methyllycaconitine (MLA). Collectively, these data indicate that PNU-120596 increases the effective dose range of donepezil in learning/memory-related tasks in young and age-impaired animal models. The results suggest that α7-nAChR-selective PAMs like PNU-120596 have potential as adjunctive treatments with acetylcholinesterase inhibitors (e.g., donepezil) for age-related illnesses such as AD as well memory disorders not necessarily associated with advanced age.
PMCID: PMC3562411  PMID: 23168113
Alzheimer’s Disease; cholinergic; memory; pro-cognitive; Mild Cognitive Impairment; aging
9.  Acetylcholinesterase inhibitors attenuate angiogenesis 
Donepezil {(RS)-2-[(1-benzyl-4-piperidyl)methyl]-5,6-dimethoxy-2,3-dihydroinden-1-one} is a reversible acetylcholinesterase inhibitor and used for treatment of patients with AD (Alzheimer's disease). Recent studies showed that treatment with donepezil reduced production of inflammatory cytokines in PBMCs (peripheral blood mononuclear cells). It was also reported that muscle-derived inflammatory cytokines play a critical role in neovascularization in a hindlimb ischaemia model. We sought to determine whether donepezil affects angiogenesis. A hindlimb ischaemia model was created by unilateral femoral artery ligation. Blood flow recovery examined by laser Doppler perfusion imaging and capillary density by immunohistochemical staining of CD31-positive cells in the ischaemic hindlimb were significantly decreased in donepezil- and physostigmine-treated mice compared with control mice after 2 weeks. Donepezil reduced expression of IL (interleukin)-1β and VEGF (vascular endothelial growth factor) in the ischaemic hindlimb. Intramuscular injections of IL-1β to the ischaemic hindlimb reversed the donepezil-induced VEGF down-regulation and the anti-angiogenic effect. Hypoxia induced IL-1β expression in C2C12 myoblast cells, which was inhibited by pre-incubation with ACh (acetylcholine) or LY294002, a PI3K (phosphoinositide 3-kinase) inhibitor. Donepezil inhibited phosphorylation of Akt [also known as PKB (protein kinase B)], a downstream kinase of PI3K, in the ischaemic hindlimb. These findings suggest that cholinergic stimulation by acetylcholinesterase inhibitors suppresses angiogenesis through inhibition of PI3K-mediated IL-1β induction, which is followed by reduction of VEGF expression. Acetylcholinesterase inhibitor may be a novel anti-angiogenic therapy.
PMCID: PMC3359057  PMID: 22369073
acetylcholinesterase inhibitor; angiogenesis; hindlimb ischaemia; interleukin-1β; ACh, acetylcholine; AD, Alzheimer's disease; bFGF, basic fibroblast growth factor; BP, blood pressure; CNS, central nervous system; COPD, chronic obstructive pulmonary disease; DMEM, Dulbecco's modified Eagle's medium; donepezil, (RS)-2-[(1-benzyl-4-piperidyl)methyl]-5,6-dimethoxy-2,3-dihydroinden-1-one; ERK, extracellular-signal-regulated kinase; FBS, fetal bovine serum; HPF, high-power field; HR, heart rate; IL, interleukin; JNK, c-Jun N-terminal kinase; LPS, lipopolysaccharide; mAChR, muscarinic ACh receptor; MAPK, mitogen-activated protein kinase; nAChR, nicotinic ACh receptor; NF-κB, nuclear factor κB; PBMC, peripheral blood mononuclear cell; PDGF, platelet-derived growth factor; PI3K, phosphoinositide 3-kinase; PTEN, phosphatase and tensin homologue deleted on chromosome 10; qRT–PCR, quantitative reverse transcription–PCR; TNFα, tumour necrosis factor α; VEGF, vascular endothelial growth factor
10.  Donepezil in Alzheimer’s disease: From conventional trials to pharmacogenetics 
Donepezil is the leading compound for the treatment of Alzheimer’s disease (AD) in more than 50 countries. As compared with other conventional acetylcholinesterase inhibitors (AChEIs), donepezil is a highly selective and reversible piperidine derivative with AChEI activity that exhibits the best pharmacological profile in terms of cognitive improvement, responders rate (40%–58%), dropout cases (5%–13%), and side-effects (6%–13%) in AD. Although donepezil represents a non cost-effective treatment, most studies convey that this drug can provide a modest benefit on cognition, behavior, and activities of the daily living in both moderate and severe AD, contributing to slow down disease progression and, to a lesser exetnt, to delay institutionalization. Patients with vascular dementia might also benefit from donepezil in a similar fashion to AD patients. Some potential effects of donepezil on the AD brain, leading to reduced cortico-hippocampal atrophy, include the following: AChE inhibition, enhancement of cholinergic neurotransmission and putative modulation of other neurotransmitter systems, protection against glutamate-induced excitotoxicity, activation of neurotrophic mechanisms, promotion of non-amyloidodgenic pathways for APP processing, and indirect effects on cerebrovascular function improving brain perfusion. Recent studies demonstrate that the therapeutic response in AD is genotype-specific. Donepezil is metabolized via CYP-related enzymes, especially CYP2D6, CYP3A4, and CYP1A2. Approximately, 15%–20% of the AD population may exhibit an abnormal metabolism of AChEIs; about 50% of this population cluster would show an ultrarapid metabolism, requiring higher doses of AChEIs to reach a therapeutic threshold, whereas the other 50% of the cluster would exhibit a poor metabolism, displaying potential adverse events at low doses. In AD patients treated with a multifactorial therapy, including donepezil, the best responders are the CYP2D6-related extensive (EM)(*1/*1, *1/*10) (57.47%) and intermediate metabolizers (IM)(*1/*3, *1/*5, *1/*6, *7/*10) (25.29%), and the worst responders are the poor (PM) (*4/*4)(9.20%) and ultra-rapid metabolizers (UM) (*1×N/*1) (8.04%). Pharmacogenetic and pharmacogenomic factors may account for 75%–85% of the therapeutic response in AD patients treated with donepezil and other AChEIs metabolized via enzymes of the CYP family. The implementation of pharmacogenetic protocols can optimize AD therapeutics.
PMCID: PMC2654795  PMID: 19300564
donepezil; Alzheimer’s disease; vascular dementia; CNS disorders; pharmacokinetics; pharmacodynamics; CYP2D6; pharmacogenetics
11.  Conformational analysis and parallel QM/MM X-ray refinement of protein bound anti-Alzheimer drug donepezil 
The recognition and association of donepezil with acetylcholinesterase (AChE) has been extensively studied in the past several decades because of the former’s use as a palliative treatment for mild Alzheimer disease. Herein we examine the conformational properties of donepezil and we re-examine the donepezil-AChE crystal structure using combined quantum mechanical/molecular mechanical (QM/MM) X-ray refinement tools. Donepezil’s conformational energy surface was explored using the M06 suite of density functionals and with the MP2/complete basis set (CBS) method using the aug-cc-pVXZ (X = D and T) basis sets. The donepezil-AChE complex (PDB 1EVE) was also re-refined through a parallel QM/MM X-ray refinement approach based on an in-house ab initio code QUICK, which uses the message passing interface (MPI) in a distributed SCF algorithm to accelerate the calculation via parallelization. In the QM/MM re-refined donepezil structure, coordinate errors that previously existed in the PDB deposited geometry were improved leading to an improvement of the modeling of the interaction between donepezil and the aromatic side chains located in the AChE active site gorge. As a result of the re-refinement there was a 93% reduction in the donepezil conformational strain energy versus the original PDB structure. The results of the present effort offer further detailed structural and biochemical inhibitor-AChE information for the continued development of more effective and palliative treatments of Alzheimer disease.
PMCID: PMC3601759  PMID: 23526889
12.  Different Cholinesterase Inhibitor Effects on CSF Cholinesterases in Alzheimer Patients 
Current Alzheimer research  2009;6(1):4-14.
The current study aimed to compare the effects of different cholinesterase inhibitors on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities and protein levels, in the cerebrospinal fluid (CSF) of Alzheimer disease (AD) patients.
Methods and Findings
AD patients aged 50–85 years were randomized to open-label treatment with oral rivastigmine, donepezil or galantamine for 13 weeks. AChE and BuChE activities were assayed by Ellman’s colorimetric method. Protein levels were assessed by enzyme-linked immunosorbent assay (ELISA). Primary analyses were based on the Completer population (randomized patients who completed Week 13 assessments). 63 patients were randomized to treatment. Rivastigmine was associated with decreased AChE activity by 42.6% and decreased AChE protein levels by 9.3%, and decreased BuChE activity by 45.6% and decreased BuChE protein levels by 21.8%. Galantamine decreased AChE activity by 2.1% and BuChE activity by 0.5%, but increased AChE protein levels by 51.2% and BuChE protein levels by10.5%. Donepezil increased AChE and BuChE activities by 11.8% and 2.8%, respectively. Donepezil caused a 215.2%increase in AChE and 0.4% increase in BuChE protein levels. Changes in mean AChE-Readthrough/Synaptic ratios, which might reflect underlying neurodegenerative processes, were 1.4, 0.6, and 0.4 for rivastigmine, donepezil and galantamine, respectively.
The findings suggest pharmacologically-induced differences between rivastigmine, donepezil and galantamine. Rivastigmine provides sustained inhibition of AChE and BuChE, while donepezil and galantamine do not inhibit BuChE and are associated with increases in CSF AChE protein levels. The clinical implications require evaluation.
PMCID: PMC4046577  PMID: 19199870
Acetylcholinesterase; Alzheimer’s disease; Butyrylcholinesterase; Cerebrospinal fluid (CSF); Cholinesterase inhibitors
13.  Effects of thyroxine and donepezil on hippocampal acetylcholine content, acetylcholinesterase activity, synaptotagmin-1 and SNAP-25 expression in hypothyroid adult rats 
Molecular Medicine Reports  2014;11(2):775-782.
A growing number of studies have revealed that neurocognitive impairment, induced by adult-onset hypothyroidism, may not be fully restored by traditional hormone substitution therapies, including thyroxine (T4). The present study has investigated the effect of T4 and donepezil (DON; an acetylcholinesterase (AChE) inhibitor) treatment on the hypothyroidism-induced alterations of acetylcholine (ACh) content and AChE activity. Furthermore, we examined synaptotagmin-1 (syt-1) and SNAP-25 expression in the hippocampus of adult rats. Adding 0.05% propylthiouracil to their drinking water for five weeks induced hypothyroidism in the rat models. From the fourth week, the rats were treated with T4, DON or a combination of both. Concentration of ACh and the activity of AChE was determined colorimetrically. The results demonstrated that hypothyroidism induced a significant decrease of Ach content and AChE activity (by 17 and 34%, respectively), which were restored to control values by T4 administration. DON treatment also restored Ach to the normal level. Protein levels of syt-1 and SNAP-25 were determined by immunohistochemistry. The results demonstrated that syt-1 was expressed at significantly lower levels in hypothyroid rats, while SNAP-25 levels were notably higher compared with the controls. Two-week treatment with T4 alone failed to normalize the expression levels of these two proteins, while co-administration of T4 and DON was able to induce this effect. These data suggested that the thyroid hormone, T4, may have a direct effect on the metabolism of hippocampal ACh in adult rats, and that the DON treatment may facilitate the recovery of synaptic protein impairments induced by hypothyroidism.
PMCID: PMC4262484  PMID: 25371181
hypothyroidism; hippocampus; thyroxine; donepezil; acetylcholine; acetylcholinesterase; synaptotagmin-1; SNAP-25
14.  Effects of thyroxin and donepezil on hippocampal acetylcholine content and syntaxin-1 and munc-18 expression in adult rats with hypothyroidism 
Adult-onset hypothyroidism induces various impairments in hippocampus-dependent cognitive function, in which numerous synaptic proteins and neurotransmitters are involved. Donepezil (DON), an acetylcholinesterase inhibitor, has been shown to be efficient in improving cognitive function. The aim of the present study was to investigate the effects of adult-onset hypothyroidism on the expression levels of the synaptic proteins syntaxin-1 and munc-18, as well as the content of the neurotransmitter acetylcholine (ACh) in the hippocampus. In addition, the study explored the effects of thyroxin (T4) and DON treatment on the altered parameters. The study involved 55 Sprague-Dawley rats that were randomly divided into five groups: Control, hypothyroid (0.05% 6-n-propyl-2-thiouracil; added to the drinking water), hypothyroid treated with T4 (6 μg/100 g body weight once daily; intraperitoneal injection), hypothyroid treated with DON (0.005%; added to the drinking water) and hypothyroid treated with a combination of the two drugs (6 μg/100 g T4 and 0.005% DON). The concentration of ACh was determined in the homogenized hippocampus of each animal by alkaline hydroxylamine colorimetry. The protein levels of syntaxin-1 and munc-18 were determined by immunohistochemistry. The results showed that the content of ACh in the hippocampi of the hypothyroid rats was significantly decreased compared with that in the controls and that T4 monotherapy and DON administration restored the ACh content to normal values. In the hippocampi of the hypothyroid group, munc-18 was expressed at significantly lower levels, while the expression levels of syntaxin-1 were increased compared with the levels in the control group. Treatment with T4 alone restored the expression of syntaxin-1 but failed to normalize munc-18 expression levels. The co-administration of T4 and DON returned the munc-18 levels to normal values. These observations indicate that adult-onset hypothyroidism induces alterations in the levels of munc-18, syntaxin-1 and ACh in the hippocampus. Syntaxin-1 and ACh levels were restored by T4 monotherapy while munc-18 levels were not. In addition, the co-administration of T4 and DON resulted in more effective restoration than either alone. The thyroid hormone has a direct effect on metabolism of hippocampal ACh in adult rats and DON is helpful for treatment of synaptic protein impairment induced by hypothyroidism.
PMCID: PMC3919934  PMID: 24520241
hypothyroidism; hippocampus; thyroxin; donepezil; acetylcholine; syntaxin-1; munc-18
15.  Donepezil Is Ineffective in Promoting Motor and Cognitive Benefits after Controlled Cortical Impact Injury in Male Rats 
Journal of Neurotrauma  2013;30(7):557-564.
The acetylcholinesterase (AChE) inhibitor donepezil is used as a therapy for Alzheimer's disease and has been recommended as a treatment for enhancing attention and memory after traumatic brain injury (TBI). Although select clinical case studies support the use of donepezil for enhancing cognition, there is a paucity of experimental TBI studies assessing the potential efficacy of this pharmacotherapy. Hence, the aim of this pre-clinical study was to evaluate several doses of donepezil to determine its effect on functional outcome after TBI. Ninety anesthetized adult male rats received a controlled cortical impact (CCI; 2.8 mm cortical depth at 4 m/sec) or sham injury, and then were randomly assigned to six TBI and six sham groups (donepezil 0.25, 0.5, 1.0, 2.0, or 3.0 mg/kg, and saline vehicle 1.0 mL/kg). Treatments began 24 h after surgery and were administered i.p. once daily for 19 days. Function was assessed by motor (beam balance/walk) and cognitive (Morris water maze) tests on days 1–5 and 14–19, respectively. No significant differences were observed among the sham control groups in any evaluation, regardless of dose, and therefore the data were pooled. Furthermore, no significant differences were revealed among the TBI groups in acute neurological assessments (e.g., righting reflex), suggesting that all groups received the same level of injury severity. None of the five doses of donepezil improved motor or cognitive function relative to vehicle-treated controls. Moreover, the two highest doses significantly impaired beam-balance (3.0 mg/kg), beam-walk (2.0 mg/kg and 3.0 mg/kg), and cognitive performance (3.0 mg/kg) versus vehicle. These data indicate that chronic administration of donepezil is not only ineffective in promoting functional improvement after moderate CCI injury, but depending on the dose is actually detrimental to the recovery process. Further work is necessary to determine if other AChE inhibitors exert similar effects after TBI.
PMCID: PMC3636588  PMID: 23227953
AChE inhibitor; behavior; CCI; functional recovery; learning and memory; Morris water maze; TBI
16.  Synthesis and in silico evaluation of 1N-methyl-1S-methyl-2-nitroethylene (NMSM) derivatives against Alzheimer disease: to understand their interacting mechanism with acetylcholinesterase 
Journal of Chemical Biology  2012;5(4):151-166.
Anomalous action of human acetylcholinesterase (hAChE) in Alzheimer’s disease (AD) was restrained by various AChE inhibitors, of which the specific and potent lead candidate Donepezil is used for treating the disease AD. Besides the specificity, the observed undesirable side effects caused by Donepezil invoked the quest for new lead molecules with the increased potency and specificity for AChE. The present study elucidates the potency of six 1N-methyl-1S-methyl-2-nitroethylene (NMSM) derivatives to form a specific interaction with the peripheral anionic site and catalytic anionic subsite residues of hAChE. The NMSMs were prepared in good yield from 1,1-di(methylsulfanyl)-2-nitroethylene and primary amine (or) amino acid esters. In silico interaction analysis reveals specific and potent interactions between hAChE and selected ligand molecules. The site-specific interactions formed between these molecules also results in a conformational change in the orientation of active site residues of hAChE, which prevents them from being accessed by beta-amyloid protein (Aβ), which is a causative agent for amyloid plaque formation and acetylcholine (ACh). In silico interaction analysis between the ligand-bounded hAChE with Aß and ACh confirms this observation. The variation in the conformation of hAChE associated with the decreased ability of Aβ and ACh to access the respective functional residues of hAChE induced by the novel NMSMs favors their selection for in vivo analysis to present themselves as new members of hAChE inhibitors.
PMCID: PMC3461197  PMID: 24052808
Alzheimer’s disease; Human acetylcholinesterase (hAChE); Amyloid beta (Aβ); 1N-methyl-1S-methyl-2-nitroethylene (NMSM); Donepezil and molecular docking calculation
17.  Description of 3,180 Courses of Chelation with Dimercaptosuccinic Acid in Children ≤5 y with Severe Lead Poisoning in Zamfara, Northern Nigeria: A Retrospective Analysis of Programme Data 
PLoS Medicine  2014;11(10):e1001739.
Jane Greig and colleagues from the medical humanitarian organization Médecins Sans Frontières describe the use of the oral chelating agent dimercaptosuccinic acid (DMSA) in several thousand young children with severe lead poisoning as a result of an environmental disaster in Zamfara, northern Nigeria.
Please see later in the article for the Editors' Summary
In 2010, Médecins Sans Frontières (MSF) discovered extensive lead poisoning impacting several thousand children in rural northern Nigeria. An estimated 400 fatalities had occurred over 3 mo. The US Centers for Disease Control and Prevention (CDC) confirmed widespread contamination from lead-rich ore being processed for gold, and environmental management was begun. MSF commenced a medical management programme that included treatment with the oral chelating agent 2,3-dimercaptosuccinic acid (DMSA, succimer). Here we describe and evaluate the changes in venous blood lead level (VBLL) associated with DMSA treatment in the largest cohort of children ≤5 y of age with severe paediatric lead intoxication reported to date to our knowledge.
Methods and Findings
In a retrospective analysis of programme data, we describe change in VBLL after DMSA treatment courses in a cohort of 1,156 children ≤5 y of age who underwent between one and 15 courses of chelation treatment. Courses of DMSA of 19 or 28 d duration administered to children with VBLL ≥ 45 µg/dl were included. Impact of DMSA was calculated as end-course VBLL as a percentage of pre-course VBLL (ECP). Mixed model regression with nested random effects was used to evaluate the relative associations of covariates with ECP. Of 3,180 treatment courses administered, 36% and 6% of courses commenced with VBLL ≥ 80 µg/dl and ≥ 120 µg/dl, respectively. Overall mean ECP was 74.5% (95% CI 69.7%–79.7%); among 159 inpatient courses, ECP was 47.7% (95% CI 39.7%–57.3%). ECP after 19-d courses (n = 2,262) was lower in older children, first-ever courses, courses with a longer interval since a previous course, courses with more directly observed doses, and courses with higher pre-course VBLLs. Low haemoglobin was associated with higher ECP. Twenty children aged ≤5 y who commenced chelation died during the period studied, with lead poisoning a primary factor in six deaths. Monitoring of alanine transaminase (ALT), creatinine, and full blood count revealed moderate ALT elevation in <2.5% of courses. No clinically severe adverse drug effects were observed, and no laboratory findings required discontinuation of treatment. Limitations include that this was a retrospective analysis of clinical data, and unmeasured variables related to environmental exposures could not be accounted for.
Oral DMSA was a pharmacodynamically effective chelating agent for the treatment of severe childhood lead poisoning in a resource-limited setting. Re-exposure to lead, despite efforts to remediate the environment, and non-adherence may have influenced the impact of outpatient treatment.
Please see later in the article for the Editors' Summary
Editors' Summary
Lead, a toxic metal that occurs naturally in the earth's crust, is now present throughout the environment because of human activities. For many years, lead was added to paint and gasoline and used in solder for water pipes. In addition, the mining, smelting, and refining of some metallic ores releases lead into the environment. Inhalation of contaminated air, consumption of contaminated food and water, and contact with dust that contains lead raises venous blood lead levels (VBLLs) and causes many health problems, particularly in children. Children who ingest large amounts of lead can develop anemia, muscle weakness, kidney damage, and life-threatening encephalopathy (brain swelling). Although fatal lead poisoning is now rare in resource-rich countries, it nevertheless remains a major global health problem. Over a three-month period in early 2010, for example, about 400 young children died in Zamfara State, Nigeria, from unexplained, intractable fits. By May 2010, it was clear that recently expanded gold mining had caused widespread environmental lead contamination in the region, and an environmental management program was begun to reduce lead levels in the surface soils.
Why Was This Study Done?
In response to the lead poisoning outbreak, the not-for-profit organization Médecins Sans Frontières (MSF) began a medical management program to reduce VBLLs that included treatment with the oral chelation agent dimercaptosuccinic acid (DMSA). Chelation agents bind metal ions and facilitate their removal from the body, thereby reducing the likelihood of lead moving from the blood to the brain. Lead encephalopathy has been commonly treated by injecting another chelator called CaNa2EDTA, but the discovery of more than 1,000 cases of childhood lead poisoning in rural villages in Nigeria meant that MSF needed a chelation approach that could be applied rapidly in a remote resource-limited setting. Additionally, although CaNa2EDTA has been in common use for severe lead poisoning for longer than DMSA, and is commonly recommended in guidelines, the evidence base does not support one treatment as superior. Here, in a retrospective analysis of MSF program data, the researchers evaluate the changes in VBLLs before and after courses of oral DMSA treatment in children aged five years and below living in Zamfara to gain new insights into this understudied treatment for severe childhood lead poisoning.
What Did the Researchers Do and Find?
The researchers measured VBLLs before and after treatment with DMSA in 1,156 children (inpatient and outpatient) with high amounts of lead in their blood who underwent one or more courses of chelation treatment lasting 19 or 28 days by calculating each child's end-course VBLL as a percentage of the child's pre-course VBLL (ECP). Considering all the treatment courses given between June 2010 and June 2011, the mean (average) ECP was 74.5%. That is, on average, VBLLs measured at the end of treatment courses were reduced by a quarter compared to VBLLs at the start of treatment courses. Among 159 inpatient courses of DMSA, the ECP was 47.7% (a halving of pre-course VBLLs). The ECP after 19-day courses was lower in older children, after first-ever courses, after courses with a longer interval since a previous course, after courses that included more directly observed doses (DMSA given in the presence of a health-care worker), and in children with higher pre-course VBLLs. Nine of the children included in this analysis died during the study period; lead poisoning was probably involved in three of these deaths. Importantly, no clinically severe adverse effects related to DMSA were seen during the study period, and no laboratory findings were recorded that required treatment discontinuation.
What Do These Findings Mean?
Because many changes were made to the treatment given to the affected children in Zamfara during the study period and because no information is presented here on clinical outcomes, these findings cannot be used to reach any definitive conclusions about the effectiveness or safety of oral DMSA as a treatment for lead poisoning in young children. However, these findings show that chelation was associated with a large reduction in the death rate among probable or suspected cases of childhood lead poisoning in Zamfara and provide new information about oral chelation that may help agencies such as MSF provide urgent treatment for lead poisoning in resource-limited settings where intravenous chelation is not feasible. Moreover, the finding of a lower ECP after inpatient treatment courses compared to after outpatient courses suggests that re-exposure to lead and non-adherence to treatment may have influenced the impact of outpatient treatments. Thus, it is essential that medical management of lead poisoning in resource-limited settings be accompanied by environmental remediation and that efforts are made to support adherence to treatment in the community by implementing directly observed treatment wherever possible.
Additional Information
Please access these websites via the online version of this summary at
A related PLOS ONE Research Article by Greig et al. provides information about the association between VBLLs and neurological features in children affected by the acute lead poisoning outbreak in Zamfara
MSF provides information about the lead poisoning crisis in Zamfara State
Human Rights Watch, an international organization that works to uphold human dignity and advance the cause of human rights for all, also provides information about lead poisoning in Zamfara State, including photographs and a video
Tox Town, an interactive site about environmental health concerns from the US National Library of Medicine, provides information on exposure to lead (in English and Spanish)
The US Environmental Protection Agency provides information on lead and lead poisoning (in English and Spanish)
The US Centers for Disease Control and Prevention provides information about lead in the environment and about its lead poisoning prevention program
MedlinePlus provides a list of links to further information about lead poisoning (in English and Spanish)
PMCID: PMC4188566  PMID: 25291378
18.  Acetylcholine and memory-enhancing activity of Ficus racemosa bark 
Pharmacognosy Research  2011;3(4):246-249.
Alzheimer's disease (AD) is a progressive neurodegenerative disorder resulting in dementia and enhancement of acetylcholine (Ach) levels in brain using acetylcholinesterase inhibitors is one of the most important approaches for the treatment of AD.
In this study, aqueous extract of Ficus racemosa Linn. (Moraceae) bark having anti-inflammatory, antioxidant, and anticholinesterase activity was evaluated for its ability to enhance Ach levels, and to ascertain its antidementia activity in rats. This work was carried out under the assumption that the F. racemosa extract may show combination of actions which could be beneficial in the treatment of AD, such as neuroprotection, attributed to antioxidant and anti-infl ammatory property and may elevate levels of Ach like Ficus hispida extract reported earlier.
Administration of the extract at two levels viz., 250 and 500 mg/kg signifi cantly raised (P ≤ 0.05) Ach levels in hippocampi of rats compared to control. The percentage enhancement in Ach levels was found to be 22% and 38%, respectively. Further, the extract at both dosage levels elicited signifi cant reduction (P ≤ 0.05) in transfer latency on elevated plus-maze, which was used as an exteroceptive behavioral model to evaluate memory in rats.
It is inferred that it would be worthwhile to explore the potential of F. racemosa in the management of Alzheimer disease.
PMCID: PMC3249783  PMID: 22224047
Acetylcholine; Alzheimer disease; memory; plus-maze; transfer latency
19.  Degree of inhibition of cortical acetylcholinesterase activity and cognitive effects by donepezil treatment in Alzheimer's disease 
Objectives: To determine in vivo cortical acetylcholinesterase (AChE) activity and cognitive effects in subjects with mild Alzheimer's disease (AD, n = 14) prior to and after 12 weeks of donepezil therapy.
Methods: Cognitive and N-[11C]methyl-piperidin-4-yl propionate ([11C]PMP) AChE positron emission tomography (PET) assessments before and after donepezil therapy.
Results: Analysis of the PET data revealed mean (temporal, parietal, and frontal) cortical donepezil induced AChE inhibition of 19.1% (SD 9.4%) (t = –7.9; p<0.0001). Enzyme inhibition was most robust in the anterior cingulate cortex (24.2% (6.9%), t = –14.1; p<0.0001). Donepezil induced cortical inhibition of AChE activity correlated with changes in the Stroop Color Word interference scores (R2 = 0.59, p<0.01), but not with primary memory test scores. Analysis of the Stroop test data indicated that subjects with AChE inhibition greater than the median value (>22.2%) had improved scores on the Stroop Color Word Test compared with subjects with less inhibition who had stable to worsening scores (t = –2.7; p<0.05).
Conclusions: Donepezil induced inhibition of cortical AChE enzyme activity is modest in patients with mild AD. The degree of cortical enzyme inhibition correlates with changes in executive and attentional functions.
PMCID: PMC1739536  PMID: 15716518
20.  Dual Effect of Beta-Amyloid on α7 and α4β2 Nicotinic Receptors Controlling the Release of Glutamate, Aspartate and GABA in Rat Hippocampus 
PLoS ONE  2012;7(1):e29661.
We previously showed that beta-amyloid (Aβ), a peptide considered as relevant to Alzheimer's Disease, is able to act as a neuromodulator affecting neurotransmitter release in absence of evident sign of neurotoxicity in two different rat brain areas. In this paper we focused on the hippocampus, a brain area which is sensitive to Alzheimer's Disease pathology, evaluating the effect of Aβ (at different concentrations) on the neurotransmitter release stimulated by the activation of pre-synaptic cholinergic nicotinic receptors (nAChRs, α4β2 and α7 subtypes). Particularly, we focused on some neurotransmitters that are usually involved in learning and memory: glutamate, aspartate and GABA.
We used a dual approach: in vivo experiments (microdialysis technique on freely moving rats) in parallel to in vitro experiments (isolated nerve endings derived from rat hippocampus). Both in vivo and in vitro the administration of nicotine stimulated an overflow of aspartate, glutamate and GABA. This effect was greatly inhibited by the highest concentrations of Aβ considered (10 µM in vivo and 100 nM in vitro). In vivo administration of 100 nM Aβ (the lowest concentration considered) potentiated the GABA overflow evoked by nicotine. All these effects were specific for Aβ and for nicotinic secretory stimuli. The in vitro administration of either choline or 5-Iodo-A-85380 dihydrochloride (α7 and α4β2 nAChRs selective agonists, respectively) elicited the hippocampal release of aspartate, glutamate, and GABA. High Aβ concentrations (100 nM) inhibited the overflow of all three neurotransmitters evoked by both choline and 5-Iodo-A-85380 dihydrochloride. On the contrary, low Aβ concentrations (1 nM and 100 pM) selectively acted on α7 subtypes potentiating the choline-induced release of both aspartate and glutamate, but not the one of GABA.
The results reinforce the concept that Aβ has relevant neuromodulatory effects, which may span from facilitation to inhibition of stimulated release depending upon the concentration used.
PMCID: PMC3256170  PMID: 22253754
Toxicology and applied pharmacology  2011;256(3):324-329.
Endocannabinoids (eCBs) modulate neurotransmission by inhibiting the release of a variety of neurotransmitters. The cannabinoid receptor agonist WIN 55,212-2 (WIN) can modulate organophosphorus (OP) anticholinesterase toxicity in rats, presumably by inhibiting acetylcholine (ACh) release. Some OP anticholinesterases also inhibit eCB-degrading enzymes. We studied the effects of the OP insecticide chlorpyrifos (CPF) on cholinergic signs of toxicity, cholinesterase activity and ACh release in tissues from wild type (+/+) and cannabinoid CB1 receptor knockout (−/−) mice. Mice of both genotypes (n=5–6/treatment group) were challenged with CPF (300 mg/kg, 2 ml/kg in peanut oil, sc) and evaluated for functional and neurochemical changes. Both genotypes exhibited similar cholinergic signs and cholinesterase inhibition (82–95% at 48 h after dosing) in cortex, cerebellum and heart. WIN reduced depolarization-induced ACh release in vitro in hippocampal slices from wild type mice, but had no effect in hippocampal slices from knockouts or in striatal slices from either genotype. Chlorpyrifos oxon (CPO, 100 μM) reduced release in hippocampal slices from both genotypes in vitro, but with a greater reduction in tissues from wild types (21% vs 12%). CPO had no significant in vitro effect on ACh release in striatum. CPF reduced ACh release in hippocampus from both genotypes ex vivo, but reduction was again significantly greater in tissues from wild types (52% vs 36%). In striatum, CPF led to a similar reduction (20–23%) in tissues from both genotypes. Thus, while CB1 deletion in mice had little influence on the expression of acute toxicity following CPF, CPF- or CPO-induced changes in ACh release appeared sensitive to modulation by CB1-mediated eCB signaling in a brain-regional manner.
PMCID: PMC3205254  PMID: 21672545
organophosphorus; insecticide; endocannabinoids; acetylcholinesterase; acute toxicity
22.  Synthesis and Evaluation of Anti-acetylcholinesterase Activity of 2-(2-(4-(2-Oxo-2-phenylethyl)piperazin-1-yl) ethyl)Isoindoline-1,3-dione Derivatives with Potential Anti-Alzheimer Effects 
Objective(s): Alzheimer's disease (AD) is a neurodegenerative disorder in elderly patients. Decrease in cholinergic neurotransmission is the main known cause in the pathophysiology of the disease. Improvement and potentiation of the cholinergic system could be beneficial for treatment of the AD. Acetylcholinesterase inhibitors such as donepezil can enhance the duration of action of acetylcholine (Ach) and therefore, through this mechanism improve the symptoms of AD. Materials and Methods: In the current study, based on the potential inhibitory activity of phthalimide derivatives towards acetylcholinesterase enzyme, a new series of phthalimide-based compounds were synthesized (4a-4e) and anti-acetylcholinesterase effect was assessed using Ellman's test. Compound 4b with 4-Fluorophenyl moiety was the most potent derivative in this series (IC50 = 16.42 ± 1.07 µM). It was shown that, none of the synthesized compounds showed superior inhibitory potency compared to donepezil (0.41 ± 0.09 µM) as a reference drug.
Conclusion: The new synthesized phthalimide based analogs could function as potential acetylcholinesterase inhibitors. Further studies are necessary for development of potent analogs.
PMCID: PMC3874090  PMID: 24379961
Acetylcholinesterase Alzheimer; Phthalimide; Synthesis
23.  Insights and Ideas Garnered from Marine Metabolites for Development of Dual-Function Acetylcholinesterase and Amyloid-β Aggregation Inhibitors 
Marine Drugs  2014;12(4):2114-2131.
Due to the diversity of biological activities that can be found in aquatic ecosystems, marine metabolites have been an active area of drug discovery for the last 30 years. Marine metabolites have been found to inhibit a number of enzymes important in the treatment of human disease. Here, we focus on marine metabolites that inhibit the enzyme acetylcholinesterase, which is the cellular target for treatment of early-stage Alzheimer’s disease. Currently, development of anticholinesterase drugs with improved potency, and drugs that act as dual acetylcholinesterase and amyloid-β aggregation inhibitors, are being sought to treat Alzheimer’s disease. Seven classes of marine metabolites are reported to possess anti-cholinesterase activity. We compared these metabolites to clinically-used acetylcholinesterase inhibitors having known mechanisms of inhibition. We performed a docking simulation and compared them to published experimental data for each metabolite to determine the most likely mechanism of inhibition for each class of marine inhibitor. Our results indicate that several marine metabolites bind to regions of the acetylcholinesterase active site that are not bound by the clinically-used drugs rivastigmine, galanthamine, donepezil, or tacrine. We use the novel poses adopted for computational drug design of tighter binding anticholinesterase drugs likely to act as inhibitors of both acetylcholinesterase activity and amyloid-β aggregation inhibition.
PMCID: PMC4012451  PMID: 24714126
molecular docking; enzyme inhibitor; sesquiterpene acetate; pyrrole; tetrazacyclopentazulene; bromotyrosine derivative; plastoquinone; farnesylacetone
24.  Effects of Donepezil on Amyloid-β and Synapse Density in the Tg2576 Mouse Model of Alzheimer's Disease 
Brain research  2009;1303:169-178.
Donepezil, an acetylcholinesterase inhibitor, is an approved drug for the treatment of Alzheimer's disease (AD). Although extensive studies have demonstrated the symptomatic efficacy of donepezil treatment in patients with AD, the effects of donepezil, if any, on the AD process are not known. In this study, we sought to determine whether long-term administration of donepezil would slow amyloid plaque deposition or confer neuronal protection in a mouse model of AD. We used quantitative light and electron microscopy to investigate the effects of long-term administration (from 3 to 9 months of age for 6 months of treatment) of donepezil (1, 2, 4 mg/kg, in drinking water) on tissue amyloid-β (Aβ) protein, plaque deposition, synaptic protein (synaptophysin) and synapse density in the hippocampus of Tg2576 mice. Administration of the 4 mg/kg dose of donepezil, as compared to vehicle and lower doses of donepezil, significantly reduced brain tissue soluble Aβ 1-40 and 1-42, Aβ plaque number, and burden at the study endpoint in Tg2576 mice. 4mg/kg of donepezil also significantly increased synaptic density in the molecular layer of the dentate gyrus in Tg2576 mice. However, a significant change of the synaptophysin-positive bouton in the hippocampus was not observed. These results suggest that a higher dose of donepezil may have a measurable impact on tissue level of Aβ protein, plaque deposition, and may prevent synapse loss in the Tg2576 mouse model of AD.
PMCID: PMC2789417  PMID: 19799879
donepezil; amyloid; synaptophysin; synapse density; Tg2576 mice; Alzheimer's disease
25.  Enhanced dendritic spine number of neurons of the prefrontal cortex, hippocampus and nucleus accumbens in old rats after chronic donepezil administration 
Synapse (New York, N.Y.)  2010;64(10):786-793.
In Alzheimer's disease brains morphological changes in the dendrites of pyramidal neurons of the prefrontal cortex (PFC) and hippocampus have been observed. These changes are particularly reflected in the decrement of both the dendritic tree and spine number. Donepezil is a potent and selective acetylcholinesterase inhibitor used in the treatment of Alzheimer's disease. We have studied the effect of oral administration of this drug on the morphology of neuronal cells from the brain of aged rats. We examined dendrites of pyramidal neurons of the PFC, dorsal or ventral hippocampus and medium spiny neurons of the nucleus accumbens (NAcc). Donepezil (1 mg/Kg, vo) was administrated every day for 60 days to rats aged 10 and 18 months. Dendritic morphology was studied by the Golgi-Cox stain procedure followed by Sholl analysis at 12 and 20 months ages, respectively. In all Donepezil treated-rats a significant increment of the dendritic spines number in pyramidal neurons of the PFC, dorsal hippocampus was observed. However, pyramidal neurons of the ventral hippocampus and medium spiny cells of the NAcc only showed an increase in the number of their spines in 12 months old-rats. Our results suggest that Donepezil prevents the alterations of the neuronal dendrite morphology caused by aging.
PMCID: PMC2948955  PMID: 20336627
dendritic morphology; prefrontal cortex; nucleus accumbens; hippocampus; Alzheimer; donepezil

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