Search

It is well known that the development of neurodegeneration, and especially Alzheimer's disease (AD), is often accompanied by impaired olfaction which precedes memory loss. A neuropeptidase neprilysin (NEP)-a principal amyloid-degrading enzyme in the brain-was also shown to be involved in olfactory signalling. Previously we have demonstrated that 5xFAD mice develop olfactory deficit by the age of 6 months which correlated with reduced NEP expression in the brain areas involved in olfactory signalling. The aim of this study was to analyse the effect of administration of a histone deacetylase inhibitor, valproic acid (VA), to adult 5xFAD mice on their olfaction and memory as well as on brain morphology and NEP expression in the parietal cortex (PC) and hippocampus (Hip). The data obtained demonstrated that administration of VA to 7-month-old mice (200 mg/kg of body weight) for 28 days resulted in improvement of their memory in the Morris water maze as well as olfaction in the odor preference and food search tests. This correlated with increased expression of NEP in the PC and Hip as well as a reduced number of amyloid plaques in these brain areas. This strongly suggests that NEP can be considered an important therapeutic target not only in AD but also in olfactory loss., Competing Interests: Declarations Ethics Approval All procedures were carried out in accordance with the international guidelines for work with experimental animals based on the European Community directive on the humane treatment of experimental animals (Directive #86 ⁄ 609 for the Care of Laboratory Animals) and NIH Guidelines for the care and use of laboratory animals (http://oacu.od.nih.gov/regs/ index.htm) and were approved by the Scientific Ethical Council of the Institute of Evolutionary Physiology and Biochemistry RAS. Consent for Publication All authors read and agreed to publish this paper. Competing Interests The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Development of the olfactory system begins early in embryogenesis and is important for the survival of new-borns in postnatal life. Olfactory malfunction in early life disrupts development of behavioural patterns while with ageing manifests development of neurodegenerative disorders. Previously, we have shown that prenatal hypoxia in rats leads to impaired olfaction in the offspring and correlates with reduced expression of a neuropeptidase neprilysin (NEP) in the brain structures involved in processing of the olfactory stimuli. Prenatal hypoxia also resulted in an increased activity of caspases in rat brain and its inhibition restored NEP content in the brain tissue and improved rat memory. In this study, we have analysed effects of intraventricular administration of a caspase inhibitor Ac-DEVD-CHO on NEP mRNA expression, the number of dendritic spines and olfactory function of rats subjected to prenatal hypoxia on E14. The data obtained demonstrated that a single injection of the inhibitor on P20 restored NEP mRNA levels and number of dendritic spines in the entorhinal and parietal cortices, hippocampus and rescued rat olfactory function in food search and odour preference tests. The data obtained suggest that caspase activation caused by prenatal hypoxia contributes to the olfactory dysfunction in developing animals and that caspase inhibition restores the olfactory deficit via upregulating NEP expression and neuronal networking. Because NEP is a major amyloid-degrading enzyme, any decrease in its expression and activity not only impairs brain functions but also predisposes to accumulation of the amyloid-β peptide and development of neurodegeneration characteristic of Alzheimer's disease., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

This review is devoted to the phenomenon of intermittent hypoxic training and is aimed at drawing the attention of researchers to the necessity of studying the mechanisms mediating the positive, particularly neuroprotective, effects of hypoxic training at the molecular level. The review briefly describes the historical aspects of studying the beneficial effects of mild hypoxia, as well as the use of hypoxic training in medicine and sports. The physiological mechanisms of hypoxic adaptation, models of hypoxic training and their effectiveness are summarized, giving examples of their beneficial effects in various organs including the brain. The review emphasizes a high, far from being realized at present, potential of hypoxic training in preventive and clinical medicine especially in the area of neurodegeneration and age-related cognitive decline., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Rybnikova, Nalivaeva, Zenko and Baranova.)

Angiotensin-converting enzyme-2, or ACE2, is primarily a zinc-dependent peptidase and ectoenzyme expressed in numerous cell types and functioning as a counterbalance to ACE in the renin-angiotensin system. It was discovered 21 years ago more than 40 years after the discovery of ACE itself. Its primary physiological activity is believed to be in the conversion of angiotensin II to the vasodilatory angiotensin-(1-7) acting through the Mas receptor. As such it has been implicated in numerous pathological conditions, largely in a protective mode which has led to the search for ACE2 activatory mechanisms. ACE2 has a diverse substrate specificity allowing its participation in multiple peptide pathways. It also regulates aspects of amino acid transport through its homology with a membrane protein, collectrin. It also serves as a viral receptor for the SARS virus, and subsequently SARS-CoV2, driving the current COVID-19 pandemic. ACE2 therefore provides a therapeutic target for the treatment of COVID and understanding the biological events following viral binding can provide insight into the multiple pathologies caused by the virus, particularly inflammatory and vascular. In part this may relate to the ability of ACE2, like ACE, to be shed from the cell membrane. The shed form of ACE2 (sACE2) may be a factor in determining susceptibility to certain COVID pathologies. Hence, for just over 20 years, ACE2 has provided numerous surprises in the field of vasoactive peptides with, no doubt, more to come but it is its central role in COVID pathology that is producing the current intense interest in its biology., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The protective effects of recombinant human lactoferrin rhLF (branded "CAPRABEL™") on the cognitive functions of rat offspring subjected to prenatal hypoxia (7% O 2 , 3 h, 14th day of gestation) have been analyzed. About 90% of rhLF in CAPRABEL was iron-free (apo-LF). Rat dams received several injections of 10 mg of CAPRABEL during either gestation (before and after the hypoxic attack) or lactation. Western blotting revealed the appearance of erythropoietin (EPO) alongside the hypoxia-inducible factors (HIFs) in organ homogenates of apo-rhLF-treated pregnant females, their embryos (but not placentas), and in suckling pups from the dams treated with apo-rhLF during lactation. Apo-rhLF injected to rat dams either during pregnancy or nurturing the pups was able to rescue cognitive deficits caused by prenatal hypoxia and improve various types of memory both in young and adult offspring when tested in the radial maze and by the Novel Object Recognition (NOR) test. The data obtained suggested that the apo-form of human LF injected to female rats during gestation or lactation protects the cognitive functions of their offspring impaired by prenatal hypoxia.

Analysis of the age-related dynamics of olfactory behavior in the odor preference and food search testsshowed that all male Wistar rats, regardless of age, preferred valerian essential oil, whose components have the properties of pheromones in rodents, when given a selection of eight essential oils; young rats displayed better food-seeking results than adult and old animals. Acute prenatal hypoxia (PH) on E14 (7% O 2 for 3 h) led to impairment of the valerian odor preference at all ages studied and to decreased productivity of food searches. Neurodegenerative processes were seen in the piriform cortex after PH, with reductions in the number of neurons and increases in glial elements. We have previously observed these changes in the entorhinal cortex and hippocampus, but not in the olfactory bulbs. This suggests that PH-induced decreases in olfactory function in rats may result from impairments to the formation of the central elements of the analyzer during the first months of postnatal ontogeny., (© Springer Nature Switzerland AG 2022.)

A neuropeptidase, neprilysin (NEP), is a major amyloid (Aβ)-degrading enzyme involved in the pathogenesis of Alzheimer's disease (AD). The olfactory system is affected early in AD with characteristic Aβ accumulation, but data on the dynamics of NEP expression in the olfactory system are absent. Our study demonstrates that NEP mRNA expression in rat olfactory bulbs (OB), entorhinal cortex (ECx), hippocampus (Hip), parietal cortex (PCx) and striatum (Str) increases during the first postnatal month being the highest in the OB and Str. By 3 months, NEP mRNA levels sharply decrease in the ECx, Hip and PCx and by 9 months in the OB, but not in the Str, which correlates with declining olfaction in aged rats tested in the food search paradigm. One-month-old rats subjected to prenatal hypoxia on E14 had lower NEP mRNA levels in the ECx, Hip and PCx (but not in the OB and Str) compared with the control offspring and demonstrated impaired olfaction in the odour preference and food search paradigms. Administration to these rats of a histone deacetylase inhibitor, sodium valproate, restored NEP expression in the ECx, Hip and PCx and improved olfaction. Our data support NEP involvement in olfactory function., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.)

The incidence of Alzheimer's disease (AD) increases significantly following chronic stress and brain ischemia which, over the years, cause accumulation of toxic amyloid species and brain damage. The effects of global 15-min ischemia and 120-min reperfusion on the levels of expression of the amyloid precursor protein (APP) and its processing were investigated in the brain cortex (Cx) of male Wistar rats. Additionally, the levels of expression of the amyloid-degrading enzymes neprilysin (NEP), endothelin-converting enzyme-1 (ECE-1), and insulin-degrading enzyme (IDE), as well as of some markers of oxidative damage were assessed. It was shown that the APP mRNA and protein levels in the rat Cx were significantly increased after the ischemic insult. Protein levels of the soluble APP fragments, especially of sAPPβ produced by β-secretase, (BACE-1) and the levels of BACE-1 mRNA and protein expression itself were also increased after ischemia. The protein levels of APP and BACE-1 in the Cx returned to the control values after 120-min reperfusion. The levels of NEP and ECE-1 mRNA also decreased after ischemia, which correlated with the decreased protein levels of these enzymes. However, we have not observed any changes in the protein levels of insulin-degrading enzyme. Contents of the markers of oxidative damage (di-tyrosine and lysine conjugates with lipid peroxidation products) were also increased after ischemia. The obtained data suggest that ischemia shifts APP processing towards the amyloidogenic β-secretase pathway and accumulation of the neurotoxic Aβ peptide as well as triggers oxidative stress in the cells. These results are discussed in the context of the role of stress and ischemia in initiation and progression of AD.

Targeting the amyloid-β (Aβ) peptide cascade has been at the heart of therapeutic developments in Alzheimer's disease (AD) research for more than 25 years, yet no successful drugs have reached the marketplace based on this hypothesis. Nevertheless, the genetic and other evidence remains strong, if not overwhelming, that Aβ is central to the disease process. Most attention has focused on the biosynthesis of Aβ from its precursor protein through the successive actions of the β- and γ-secretases leading to the development of inhibitors of these membrane proteases. However, the levels of Aβ are maintained through a balance of its biosynthesis and clearance, which occurs both through further proteolysis by a family of amyloid-degrading enzymes (ADEs) and by a variety of transport processes. The development of late-onset AD appears to arise from a failure of these clearance mechanisms rather than by overproduction of the peptide. This review focuses on the nature of these clearance mechanisms, particularly the various proteases known to be involved, and their regulation and potential as therapeutic targets in AD drug development. The majority of the ADEs are zinc metalloproteases [e.g., the neprilysin (NEP) family, insulin-degrading enzyme, and angiotensin converting enzymes (ACE)]. Strategies for up-regulating the expression and activity of these enzymes, such as genetic, epigenetic, stem cell technology, and other pharmacological approaches, will be highlighted. Modifiable physiological mechanisms affecting the efficiency of Aβ clearance, including brain perfusion, obesity, diabetes, and sleep, will also be outlined. These new insights provide optimism for future therapeutic developments in AD research. LINKED ARTICLES: This article is part of a themed section on Therapeutics for Dementia and Alzheimer's Disease: New Directions for Precision Medicine. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.18/issuetoc., (© 2019 The British Pharmacological Society.)

The amyloid-degrading enzyme neprilysin (NEP) is one of the therapeutic targets in prevention and treatment of Alzheimer's disease (AD). As we have shown previously NEP expression in rat parietal cortex (Cx) and hippocampus (Hip) decreases with age and is also significantly reduced after prenatal hypoxia. Following the paradigms for enhancement of NEP expression and activity developed in cell culture, we analysed the efficacy of various compounds able to upregulate NEP using our model of prenatal hypoxia in rats. In addition to the previous data demonstrating that valproic acid can upregulate NEP expression both in neuroblastoma cells and in rat Cx and Hip we have further confirmed that caspase inhibitors can also restore NEP expression in rat Cx reduced after prenatal hypoxia. Here we also report that administration of a green tea catechin epigallocatechin-3-gallate (EGCG) to adult rats subjected to prenatal hypoxia increased NEP activity in blood plasma, Cx and Hip as well as improved memory performance in the 8-arm maze and novel object recognition tests. Moreover, EGCG administration led to an increased number of dendritic spines in the hippocampal CA1 area which correlated with memory enhancement. The data obtained allowed us to conclude that the decrease in the activity of the amyloid-degrading enzyme NEP, as well as a reduction in the number of labile interneuronal contacts in the hippocampus, contribute to early cognitive deficits caused by prenatal hypoxia and that there are therapeutic avenues to restore these deficits via NEP activation which could also be used for designing preventive strategies in AD.

Using electrocorticogram (ECoG) analysis, we compared age-related dynamics of general neuronal activity and convulsive epileptiform responsiveness induced by intracortical microinjections of 4-aminopyridine (4-AP) in control Wistar rats and those subjected to prenatal hypoxia (Hx; E14; 7% O2, 3 h). The studies were carried out in three age periods roughly corresponding to childhood (P20-27), adolescence (P30-45), and adulthood (P90-120). It was found that in the process of postnatal development of the control rats, the peak of the ECoG power spectrum density (PSD) of the theta rhythm during wakefulness shifted from the low to the higher frequency, while in the Hx rats this shift had the opposite direction. Moreover, the Hx rats had different frequency characteristics of the ECoG PSD and longer episodes of spike-and-wave discharges caused by 4-AP injections compared to the controls. The total ECoG PSD of slow-wave sleep (1-5 Hz) was also dramatically decreased in the process of development of the Hx rats. Such alterations in PSD could be explained by the changes in balance of the excitation and inhibition processes in the cortical networks. Analyzing protein levels of neurotransmitter transporters in the brain structures of the Hx rats, we found that the content of the glutamate transporter EAAT1 was higher in the parietal cortex in all age groups of Hx rats while in the hippocampus it decreased during postnatal development compared to controls. Furthermore, the content of the vesicular acetylcholine transporter in the parietal cortex, and of the inhibitory GABA transporter 1 in the hippocampus, was also affected by prenatal Hx. These data suggest that prenatal Hx results in a shift in the excitatory and inhibitory balance in the rat cortex towards excitation, making the rat's brain more vulnerable to the effects of proconvulsant drugs and predisposing animals to epileptogenesis during postnatal life., (© 2019 S. Karger AG, Basel.)

This review focuses on the role of prenatal hypoxia in the development of brain functions in the postnatal period and subsequent increased risk of neurodegenerative disorders in later life. Accumulating evidence suggests that prenatal hypoxia in critical periods of brain formation results in significant changes in development of cognitive functions at various stages of postnatal life which correlate with morphological changes in brain structures involved in learning and memory. Prenatal hypoxia also leads to a decrease in brain adaptive potential and plasticity due to the disturbance in the process of formation of new contacts between cells and propagation of neuronal stimuli, especially in the cortex and hippocampus. On the other hand, prenatal hypoxia has a significant impact on expression and processing of a variety of genes involved in normal brain function and their epigenetic regulation. This results in changes in the patterns of mRNA and protein expression and their post-translational modifications, including protein misfolding and clearance. Among proteins affected by prenatal hypoxia are a key enzyme of the cholinergic system-acetylcholinesterase, and the amyloid precursor protein (APP), both of which have important roles in brain function. Disruption of their expression and metabolism caused by prenatal hypoxia can also result, apart from early cognitive dysfunctions, in development of neurodegeneration in later life. Another group of enzymes affected by prenatal hypoxia are peptidases involved in catabolism of neuropeptides, including amyloid-β peptide (Aβ). The decrease in the activity of neprilysin and other amyloid-degrading enzymes observed after prenatal hypoxia could result over the years in an Aβ clearance deficit and accumulation of its toxic species which cause neuronal cell death and development of neurodegeneration. Applying various approaches to restore expression of neuronal genes disrupted by prenatal hypoxia during postnatal development opens an avenue for therapeutic compensation of cognitive dysfunctions and prevention of Aβ accumulation in the aging brain and the model of prenatal hypoxia in rodents can be used as a reliable tool for assessment of their efficacy.

The accumulation of cerebral amyloid βpeptide (Aβ) is a key precipitating factor for neuronal cell death in Alzheimer's Disease (AD). However, brain Aβ levels are modifiable since there is a balance between its formation from the Amyloid Precursor Protein (APP) and its removal by clearance mechanisms, which can be either through proteolysis or by protein binding and subsequent transport). Among the major enzymes degrading brain Aβ are several zinc-proteases: neprilysin (NEP), its homologues NEP2 and the Endothelin Converting Enzymes (ECE-1 and -2) and also the Insulin-Degrading Enzyme (IDE). During the ageing process, and under certain pathological conditions (e.g. ischemia and stroke), the expression and activity of these enzymes decline, which leads to a deficit of Aβ clearance and its accumulation in the brain. Some of these changes in the enzyme properties are due to their reduced expression and/or structural modification by reactive oxygen species. In this review paper we shall discuss some mechanisms of regulation of Amyloid-Degrading Enzymes (ADEs) and possible therapeutic approaches which might prevent their decline with age and after pathology.

The amyloid precursor protein (APP) and acetylcholinesterase (AChE) are multi-faceted proteins with a wide range of vital functions, both crucially linked with the pathogenesis of Alzheimer's disease (AD). APP is the precursor of the Aβ peptide, the pathological agent in AD, while AChE is linked to its pathogenesis either by increasing cholinergic deficit or exacerbating Aβ fibril formation and toxicity. As such, both proteins are the main targets in AD therapeutics with AChE inhibitors being currently the only clinically available AD drugs. In our studies we have demonstrated an important inter-relation in functioning of these proteins. Both can be released from the cell membrane and we have shown that AChE shedding involves a metalloproteinase-mediated mechanism which, like the α-secretase dependent cleavage of APP, is stimulated by cholinergic agonists. Overexpression of the neuronal specific isoform APP695 in neuronal cells substantially decreased levels of the AChE mRNA, protein and catalytic activity accompanied by a similar decrease in mRNA levels of the AChE membrane anchor, PRiMA (proline rich membrane anchor). We further established that this regulation does not involve APP processing and its intracellular domain (AICD) but requires the E1 region of APP, specifically its copper-binding domain. On the contrary, siRNA knock-down of APP in cholinergic SN56 cells resulted in a significant upregulation of AChE mRNA levels. Hence APP may influence AChE physiology while released AChE may regulate amyloidogenesis through multiple mechanisms suggesting novel therapeutic targets., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

This review reflects on the origins, development, publishing trends, and scientific directions of the Journal of Neurochemistry over its 60 year lifespan as seen by key contributors to the Journal's production. The Journal first appeared in May 1956 with just two issues published in that inaugural year. By 1963, it appeared monthly and, by 2002, 24 hard copy issues were published yearly. In 2014, the Journal became online only. For much of its time, the Journal was managed through two separate editorial offices each with their respective Chief Editor (the 'Western' and 'Eastern' hemispheres). The Journal was restructured to operate through a single editorial office and Editor-in-Chief from 2013. Scientifically, the Journal progressed through distinct scientific eras with the first two decades generally centered around developments in methodology followed by a period when publications delved deeper into underlying mechanisms. By the late 1980s, the Journal had entered the age of genetics and beyond, with an increasing focus on neurodegenerative diseases. Reviews have played a regular part in the success of J Neurochem with focused special and virtual issues being a highlight of recent years. Today, 60 years and onwards, J Neurochem continues to be a leading source of top-quality, original and review articles in neuroscience. We look forward to its continued success at the forefront of neurochemistry in the decades to come. This article celebrates 60 years of publication of Journal of Neurochemistry including personal reminiscences from some of the Chief Editors, past and present, as well as input from some of the key contributors to the Journal over this period. We highlight the scientific, technological, and publishing developments along the way, with reference to key papers published in the Journal. The support of the Journal toward the aims and objectives of the International Society for Neurochemistry (ISN) is also emphasized. This article is part of the 60th Anniversary special issue., (© 2016 International Society for Neurochemistry.)

Currently, deficit of amyloid β-peptide (Aβ) clearance from the brain is considered as one of the possible causes of amyloid accumulation and neuronal death in the sporadic form of Alzheimer's disease (AD). Aβ clearance can involve either specific proteases present in the brain or Aβ-binding/transport proteins. Among amyloid-degrading enzymes the most intensively studied are neprilysin (NEP) and insulin-degrading enzyme (IDE). Since ageing and development of brain pathologies is often accompanied by a deficit in the levels of expression and activity of these enzymes in the brain, there is an urgent need to understand the mechanisms involved in their regulation. We have recently reported that NEP and also an Aβ-transport protein, transthyretin are epigenetically co-regulated by the APP intracellular domain (AICD) and this regulation depends on the cell type and APP695 isoform expression in a process that can be regulated by the tyrosine kinase inhibitor, Gleevec. We have now extended our work and shown that, unlike NEP, another amyloid-degrading enzyme, IDE, is not related to over-expression of APP695 in neuroblastoma SH-SY5Y cells but is up-regulated by APP751 and APP770 isoforms independently of AICD but correlating with reduced HDAC1 binding to its promoter. Studying the effect of the nuclear retinoid X receptor agonist, bexarotene, on NEP and IDE expression, we have found that both enzymes can be up-regulated by this compound but this mechanism is not APP-isoform specific and does not involve AICD but, on the contrary, affects HDAC1 occupancy on the NEP gene promoter. These new insights into the mechanisms of NEP and IDE regulation suggest possible pharmacological targets in developing AD therapies.

While gene mutations in the amyloid precursor protein (APP) and the presenilins lead to an accumulation of the amyloid β-peptide (Aβ) in the brain causing neurodegeneration and familial Alzheimer's disease (AD), over 95% of all AD cases are sporadic. Despite the pathologies being indistinguishable, relatively little is known about the mechanisms affecting generation of Aβ in the sporadic cases. Vascular disorders such as ischaemia and stroke are well established risk factors for the development of neurodegenerative diseases and systemic hypoxic episodes have been shown to increase Aβ production and accumulation. We have previously shown that hypoxia causes a significant decrease in the expression of the major Aβ-degrading enzyme neprilysin (NEP) which might deregulate Aβ clearance. Aβ itself is derived from the transmembrane APP along with several other biologically active metabolites including the C-terminal fragment (CTF) termed the APP intracellular domain (AICD), which regulates the expression of NEP and some other genes in neuronal cells. Here we show that in hypoxia there is a significantly increased expression of caspase-3, 8, and 9 in human neuroblastoma NB7 cells, which can degrade AICD. Using chromatin immunoprecipitation we have revealed that there was also a reduction of AICD bound to the NEP promoter region which underlies the decreased expression and activity of the enzyme under hypoxic conditions. Incubation of the cells with a caspase-3 inhibitor Z-DEVD-FMK could rescue the effect of hypoxia on NEP activity protecting the levels of AICD capable of binding the NEP promoter. These data suggest that activation of caspases might play an important role in regulation of NEP levels in the brain under pathological conditions such as hypoxia and ischaemia leading to a deficit of Aβ clearance and increasing the risk of development of AD.

Analysis of the effect of a caspase-3 inhibitor on the content of the amyloid-degrading neuropeptidase neprilysin (NEP) in the cortex of rats subjected to prenatal hypoxia (7% O2, 3 h) on the 14-th day of the embryonic development (E14) was performed. It was found that rats subjected to prenatal hypoxia on days 20-30 after birth have an increased content and activity of caspase-3 with reduced levels of NEP and of the C-terminal fragment of the amyloid precursor protein (AICD) regulating NEP expression. In hypoxic animals 3 days after a single injection of a caspase inhibitor (i. v., Ac-DEVD-CHO, P20) the content of AICD and NEP was found to be increased up to the levels observed in control rats. The data obtained suggest that the increase of caspase-3 enzyme activity could affect NEP expression via proteolytic degradation of its transcription factor AICD. These data for the first time demonstrate the role of caspases in AICD-dependent regulation of NEP production in the brain of mammals under hypoxic conditions.

Due to an increasing life expectancy in developing countries, cases of type 2 diabetes and Alzheimer's disease (AD) in the elderly are growing exponentially. Despite a causative link between diabetes and AD, general molecular mechanisms underlying pathogenesis of these disorders are still far from being understood. One of the factors leading to cell death and cognitive impairment characteristic of AD is accumulation in the brain of toxic aggregates of amyloid-β peptide (Aβ). In the normally functioning brain Aβ catabolism is regulated by a cohort of proteolytic enzymes including insulin-degrading enzyme (IDE) and their deficit with ageing can result in Aβ accumulation and increased risk of AD. The aim of this study was a comparative analysis of IDE expression in the brain structures involved in AD, as well as in peripheral organs (the liver and kidney) of rats, during natural ageing and after experimentally-induced diabetes. It was found that ageing is accompanied by a significant decrease of IDE mRNA and protein content in the liver (by 32 and 81%) and brain structures (in the cortex by 58 and 47% and in the striatum by 53 and 68%, respectively). In diabetic animals, IDE protein level was increased in the liver (by 36%) and in the striatum (by 42%) while in the brain cortex and hippocampus it was 20-30% lower than in control animals. No significant IDE protein changes were observed in the kidney of diabetic rats. These data testify that ageing and diabetes are accompanied by a deficit of IDE in the brain structures where accumulation of Aβ was reported in AD patients, which might be one of the factors predisposing to development of the sporadic form of AD in the elderly, and especially in diabetics.

This study reports the dynamics of changes in postnatal ontogenesis of the activity of soluble and membrane-bound forms of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in sensorimotor cortex of rats as well as the pattern of their changes after prenatal hypoxia (E14, 7% O2, 3 h) or acute hypoxia in adult animals (4 months, 7% O2, 3 h). In normally developing rats the activity of the membrane-bound AChE form in the sensorimotor cortex gradually increased up to the end of the first month after birth and remained at this high level during all further postnatal ontogenesis, while the activity of the soluble form of AChE reached its maximum on the 10th day after birth and decreased significantly by the end of the first month. In animals exposed to prenatal hypoxia the activity both of the soluble and membrane bound forms of AChE during the first two weeks after birth was 20-25% lower, as compared to controls but increased by the end of the first month and even exceeded the control values remaining increased up to old age (1.5 years). The activity of both BChE forms in rat sensorimotor cortex at all stages of postnatal ontogenesis was significantly lower than of AChE, although the dynamics of their changes was similar to that of AChE. Prenatal hypoxia led to a decrease in the activity of the membrane-bound form of BChE, as compared to controls, practically at all developmental stages studied, but was higher at the end of the first month after birth. At the same time, the activity of the soluble form of BChE was decreased only on the 20th day of development, as compared to the control, but increased from the end of the first month of life onwards. Acute hypoxia in adult rats also led to a decrease in the activity of both forms of AChE and BChE in the sensorimotor cortex but the dynamics of these changes was different for each enzyme. Thus, insufficient oxygen supply to the nervous tissue at different stages of ontogenesis has a significant effect on the activity and ratio of various forms of cholinesterases exhibiting either growth factor or signaling properties. This may lead to changes in brain development and formation of behavioural reactions, including learning and memory, and also increase the risk of development of the sporadic form of Alzheimer's disease (AD)--one of the most common neurodegenerative diseases of advanced age. This study expands our knowledge of the properties of brain cholinesterases under normal and pathological conditions and may be useful for developing new approaches towards prevention and treatment of AD.

Objective: To analyze the activity of acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and neprilysin (NEP) in the blood serum in elderly people with different types of cognitive impairment and evaluate the effect of ceraxon on the biochemical parameters., Material and Methods: Three groups of patients: without cognitive disorders (controls--CG), with amnestic mild cognitive impairment (а-MCI) and with Alzheimer's disease (AD were studied)., Results and Conclusion: The activity of AChE, BChE and NEP was reduced in the blood serum of patients with a-MCI and, to the greater extent, in patients with AD compared to CG and correlated with the level of cognitive dysfunction evaluated by MMSE, ADAS-cog, and other tests. For the first time, it has been shown that treatment of a-MCI patients with ceraxon (citicolin) results in an increase of the activity of blood serum AChE, BChE and NEP to the values observed in the CG. Thus, the activities of blood serum AChE, BChE and NEP reflect the level of cognitive dysfunction and can be used as prognostic biomarkers of the level of dementia progression in patients with impaired memory.

Abnormal elevation of amyloid β-peptide (Aβ) levels in the brain is the primary trigger for neuronal cell death specific to Alzheimer's disease (AD). It is now evident that Aβ levels in the brain are manipulable due to a dynamic equilibrium between its production from the amyloid precursor protein (APP) and removal by amyloid clearance proteins. Clearance can be either enzymic or non-enzymic (binding/transport proteins). Intriguingly several of the main amyloid-degrading enzymes (ADEs) are members of the M13 peptidase family (neprilysin (NEP), NEP2 and the endothelin converting enzymes (ECE-1 and -2)). A distinct metallopeptidase, insulin-degrading enzyme (IDE), also contributes to Aβ degradation in the brain. The ADE family currently embraces more than 20 members, both membrane-bound and soluble, and of differing cellular locations. NEP plays an important role in brain function terminating neuropeptide signals. Its decrease in specific brain areas with age or after hypoxia, ischaemia or stroke contribute significantly to the development of AD pathology. The recently discovered mechanism of epigenetic regulation of NEP (and other genes) by the APP intracellular domain (AICD) and its dependence on the cell type and APP isoform expression suggest possibilities for selective manipulation of NEP gene expression in neuronal cells. We have also observed that another amyloid-clearing protein, namely transthyretin (TTR), is also regulated in the neuronal cell by a mechanism similar to NEP. Dependence of amyloid clearance proteins on histone deacetylases and the ability of HDAC inhibitors to up-regulate their expression in the brain opens new avenues for developing preventive strategies in AD.

Proteolytic cleavage of the amyloid precursor protein (APP) by the successive actions of β- and γ-secretases generates several biologically active metabolites including the amyloid β-peptide (Aβ) and the APP intracellular domain (AICD). By analogy with the Notch signalling pathway, AICD has been proposed to play a role in transcriptional regulation. Among the cohort of genes regulated by AICD is the Aβ-degrading enzyme neprilysin (NEP). AICD binds to the NEP promoter causing transcriptional activation by competitive replacement with histone deacetylases (HDACs) leading to increased levels of NEP activity and hence increased Aβ clearance. We now show that the Aβ-clearance protein transthyretin (TTR) is also epigenetically up-regulated by AICD. Like NEP regulation, AICD derived specifically from the neuronal APP isoform, APP695 , binds directly to the TTR promoter displacing HDAC1 and HDAC3. Cell treatment with the tyrosine kinase inhibitor Gleevec (imatinib) or with the alkalizing agent NH4 Cl causes an accumulation of 'functional' AICD capable of up-regulating both TTR and NEP, leading to a reduction in total cellular Aβ levels. Pharmacological regulation of both NEP and TTR might represent a viable therapeutic target in Alzheimer's disease., (© 2014 International Society for Neurochemistry.)

The toxic role of amyloid β peptides in Alzheimer's disease is well documented. Their generation is via sequential β- and γ-secretase cleavage of the membrane-bound amyloid precursor protein (APP). Other APP metabolites include the soluble ectodomains sAPPα and sAPPβ and also the amyloid precursor protein intracellular domain (AICD). In this study, we examined whether APP is involved in the regulation of acetylcholinesterase (AChE), which is a key protein of the cholinergic system and has been shown to accelerate amyloid fibril formation and increase their toxicity. Overexpression of the neuronal specific isoform, APP695, in the neuronal cell lines SN56 and SH-SY5Y substantially decreased levels of AChE mRNA, protein, and catalytic activity. Although similar decreases in mRNA levels were observed of the proline-rich anchor of AChE, PRiMA, no changes were seen in mRNA levels of the related enzyme, butyryl-cholinesterase, nor of the high-affinity choline transporter. A γ-secretase inhibitor did not affect AChE transcript levels or enzyme activity in SN56 (APP695) or SH-SY5Y (APP695) cells, showing that regulation of AChE by APP does not require the generation of AICD or amyloid β peptide. Treatment of wild-type SN56 cells with siRNA targeting APP resulted in a significant up-regulation in AChE mRNA levels. Mutagenesis studies suggest that the observed transcriptional repression of AChE is mediated by the E1 region of APP, specifically its copper-binding domain, but not the C-terminal YENTPY motif. In conclusion, AChE is regulated in two neuronal cell lines by APP in a manner independent of the generation of sAPPα, sAPPβ, and AICD.

Despite intensive studies of the secretase-mediated processing of the amyloid precursor protein (APP) to form the amyloid β-peptide (Aβ), in relation to Alzheimer's disease (AD), no new therapeutic agents have reached the clinics based on reducing Aβ levels through the use of secretase inhibitors or immunotherapy. Furthermore, the normal neuronal functions of APP and its various metabolites still remain under-investigated and unclear. Here, we highlight emerging areas of APP function that may provide new insights into synaptic development, cognition, and gene regulation. By modulating expression levels of endogenous APP in primary cortical neurons, the frequency and amplitude of calcium oscillations is modified, implying a key role for APP in maintaining neuronal calcium homeostasis essential for synaptic transmission. Disruption of this homeostatic mechanism predisposes to aging and AD. Synaptic spine loss is a feature of neurogeneration resulting in learning and memory deficits, and emerging evidence indicates a role for APP, probably mediated via one or more of its metabolites, in spine structure and functions. The intracellular domain of APP (AICD) has also emerged as a key epigenetic regulator of gene expression controlling a diverse range of genes, including APP itself, the amyloid-degrading enzyme neprilysin, and aquaporin-1. A fuller understanding of the physiological and pathological actions of APP and its metabolic network could provide new opportunities for therapeutic intervention in AD., (© 2013 International Society for Neurochemistry.)

For 20 years the amyloid cascade hypothesis of Alzheimer disease (AD) has placed the amyloid-β peptide (Aβ), formed from the amyloid precursor protein (APP), centre stage in the process of neurodegeneration. However, no new therapeutic agents have reached the clinic through exploitation of the hypothesis. The APP metabolites, including Aβ, generated by its proteolytic processing, have distinct physiological functions. In particular, the cleaved intracellular domain of APP (AICD) regulates expression of several genes, including APP itself, the β-secretase BACE-1 and the Aβ-degrading enzyme, neprilysin and this transcriptional regulation involves direct promoter binding of AICD. Of the three major splice isoforms of APP (APP695, APP751, APP770), APP695 is the predominant neuronal form, from which Aβ and transcriptionally-active AICD are preferentially generated by selective processing through the amyloidogenic pathway. Despite intensive research, the normal functions of the APP isoforms remain an enigma. APP plays an important role in brain development, memory and synaptic plasticity and secreted forms of APP are neuroprotective. A fuller understanding of the physiological and pathological actions of APP and its metabolic and gene regulatory network could provide new therapeutic opportunities in neurodegeneration, including AD., (Copyright © 2013 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.)

Although acetylcholinesterase (AChE) is primarily a hydrolytic enzyme, metabolising the neurotransmitter acetylcholine in cholinergic synapses, it also has some non-catalytic functions in the brain which are far less well characterised. AChE was shown to be secreted or shed from the neuronal cell surface like several other membrane proteins, such as the amyloid precursor protein (APP). Since AChE does not possess a transmembrane domain, its anchorage in the membrane is established via the Proline Rich Membrane Anchor (PRiMA), a transmembrane protein. Both the subunit oligomerisation and membrane anchor of AChE are shared by a related enzyme, butyrylcholinesterase (BChE), the physiological function of which in the brain is unclear. In this work, we have assayed the relative activities of AChE and BChE in membrane fractions and culture medium of three different neuronal cell lines, namely the neuroblastoma cell lines SH-SY5Y and NB7 and the mouse basal forebrain cell line SN56. In an effort to understand the shedding process of AChE, we have used several pharmacological treatments, which showed that it is likely to be mediated in part by an EDTA- and batimastat-sensitive, but GM6001-insensitive metalloprotease, with the possible additional involvement of a thiol isomerase. Cellular release of AChE by SH-SY5Y is significantly enhanced by the muscarinic acetylcholine receptor (mAChR) agonists carbachol or muscarine, with the effect of carbachol blocked by the mAChR antagonist atropine. AChE has been implicated in the pathogenesis of Alzheimer's disease and it has been shown that it accelerates formation and increases toxicity of amyloid fibrils, which have been closely linked to the pathology of AD. In light of this, greater understanding of AChE and BChE physiology may also benefit AD research., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

Prevention of amyloidosis by chemical compounds is a potential therapeutic strategy in Alzheimer's, prion and other neurodegenerative diseases. Regularly branched dendrimers and less regular hyperbranched polymers have been suggested as promising inhibitors of amyloid aggregation. As demonstrated in our previous studies, some widely used dendrimers (PAMAM, PPI) could not only inhibit amyloid aggregation in solution but also dissolve mature fibrils. In this study we have performed computer simulation of polylysine dendrimers of 3rd and 5th generations (D3 and D5) and analysed the effect of these dendrimers and some hyperbranched polymers on a lysine base (HpbK) on aggregation of amyloid peptide in solution. The effects of dendrimers on cell viability and their protective action against Aβ-induced cytotoxicity and alteration of K+channels was also analysed using human neuroblastoma SH-SY5Y cells. In addition, using fluorescence microscopy, we analysed uptake of FITC-conjugated D3 by SH-SY5Y cells and its distribution in the brain after intraventricular injections to rats. Our results demonstrated that dendrimers D3 and D5 inhibited amyloid aggregation in solution while HpbK enhanced amyloid aggregation. Cell viability and patch-clamp studies have shown that D3 can protect cells against Aβ-induced cytotoxicity and K+channel modulation. In contrast, HpbK had no protective effect against Aβ. Fluorescence microscopy studies demonstrated that FITC-D3 accumulates in the vacuolar compartments of the cells and can be detected in various brain structures and populations of cells after injections to the brain. As such, polylysine dendrimers D3 and D5 can be proposed as compounds for developing antiamyloidogenic drugs.

Lipid rafts are membrane domains, more ordered than the bulk membrane and enriched in cholesterol and sphingolipids. They represent a platform for protein-lipid and protein-protein interactions and for cellular signaling events. In addition to their normal functions, including membrane trafficking, ligand binding (including viruses), axonal development and maintenance of synaptic integrity, rafts have also been implicated in the pathogenesis of several neurodegenerative diseases including Alzheimer's disease (AD). Lipid rafts promote interaction of the amyloid precursor protein (APP) with the secretase (BACE-1) responsible for generation of the amyloid β peptide, Aβ. Rafts also regulate cholinergic signaling as well as acetylcholinesterase and Aβ interaction. In addition, such major lipid raft components as cholesterol and GM1 ganglioside have been directly implicated in pathogenesis of the disease. Perturbation of lipid raft integrity can also affect various signaling pathways leading to cellular death and AD. In this review, we discuss modulation of APP cleavage by lipid rafts and their components, while also looking at more recent findings on the role of lipid rafts in signaling events.

The ADAMs (a disintegrin and metalloprotease) are a family of membrane-anchored glycoproteins capable of shedding a multitude of proteins from the cell surface. Although ADAMs are being considered as crucial modulators of physiological and pathophysiological processes, their roles in neuronal death/survival are largely unexplored. In the present study, changes in brain expression of ADAM15 and ADAM17 (TACE) have been quantitatively examined in rats in response to injurious severe hypoxia (SH) and in animals which acquired hypoxic tolerance through preconditioning to mild hypoxia prior SH. SH persistently up-regulated ADAM15 mRNA and protein levels in hippocampus and neocortex but not in thalamus or hypothalamus. This effect was not observed in the preconditioned rats tolerant to SH. In contrast, hippocampal levels of ADAM17 mRNA and neocortical levels of ADAM17 mRNA and protein were largely reduced following SH in non-preconditioned rats. Hypoxic preconditioning prevented down-regulation of the adam17 gene and considerably enhanced ADAM17 protein expression in hippocampus and neocortex in response to SH. The present findings implicate ADAM15 in the processes of neuronal hypoxic injury. On the other hand, these results also provide evidence for a pro-survival neuroprotective role of ADAM17 and its engagement in the process of preconditioning-induced hypoxic tolerance. The analysis of the protein levels of soluble and membrane-bound forms of APP in the neocortex and hippocampus of rats subjected to SH and SH with preconditioning has demonstrated that an increased ADAM17 expression in preconditioned animals 24h after hypoxia corresponded to a higher level of soluble form of APP and a reduction of the membrane bound fraction which reflects the role of ADAM17 in APP shedding., (Copyright © 2012 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.)

Alzheimer's disease (AD) is accompanied by memory loss due to neuronal cell death caused by toxic amyloid β-peptide (Aβ) aggregates. In the healthy brain, a group of amyloid-degrading enzymes including neprilysin (NEP) maintain Aβ levels at physiologically low concentrations but, with age and under some pathological conditions, expression and activity of these enzymes decline predisposing to late-onset AD. Hence, up-regulation of NEP might be a viable strategy for prevention of Aβ accumulation and development of the disease. As we have recently shown, inhibitors of histone deacetylases, in particular, valproic acid (VA), were capable of up-regulating NEP expression and activity in human neuroblastoma SH-SY5Y cell lines characterised by very low levels of NEP. In the present study, analysing the effect of i.p. injections of VA to rats, we have observed up-regulation of expression and activity of NEP in rat brain structures, in particular, in the hippocampus. This effect was brain region- and age-specific. Administration of VA has also restored NEP activity and memory deficit in adult rats caused by prenatal hypoxia. This suggests that VA and more specific HDAC inhibitors can be considered as potential pharmaceutical agents for up-regulation of NEP activity and improvement of cognitive functions of ageing brain.

Alzheimer's disease (AD) is a neurodegenerative illness and the leading cause of dementia in the elderly. The accumulation of amyloid-β peptide (Aβ) is a well-known pathological hallmark associated with the disease. However, Aβ is only one of several metabolites produced by β- and γ-secretase actions on the transmembrane protein, the amyloid precursor protein (APP). A proteolytic fragment termed the APP intracellular domain (AICD) is also produced. By analogy with the Notch signalling pathway, AICD has been proposed as a transcriptional regulator although its mechanism of action and the complement of genes regulated remain controversial. This review will focus on the contributions that studies of APP processing have brought to the understanding of a novel nuclear signalling pathway that may contribute to the pathology of AD and may provide new therapeutic opportunities., (Copyright © 2011 Elsevier Inc. All rights reserved.)

: The amyloid cascade hypothesis of Alzheimer's disease envisages that the initial elevation of amyloid β-peptide (Aβ) levels, especially of Aβ(1-42) , is the primary trigger for the neuronal cell death specific to onset of Alzheimer's disease. There is now substantial evidence that brain amyloid levels are manipulable because of a dynamic equilibrium between their synthesis from the amyloid precursor protein and their removal by amyloid-degrading enzymes (ADEs) providing a potential therapeutic strategy. Since the initial reports over a decade ago that two zinc metallopeptidases, insulin-degrading enzyme and neprilysin (NEP), contributed to amyloid degradation in the brain, there is now an embarras de richesses in relation to this category of enzymes, which currently number almost 20. These now include serine and cysteine proteinases, as well as numerous zinc peptidases. The experimental validation for each of these enzymes, and which to target, varies enormously but up-regulation of several of them individually in mouse models of Alzheimer's disease has proved effective in amyloid and plaque clearance, as well as cognitive enhancement. The relative status of each of these enzymes will be critically evaluated. NEP and its homologues, as well as insulin-degrading enzyme, remain as principal ADEs and recently discovered mechanisms of epigenetic regulation of NEP expression potentially open new avenues in manipulation of AD-related genes, including ADEs., (© 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.)

The amyloid cascade hypothesis of Alzheimer's disease (AD) postulates that accumulation in the brain of amyloid β-peptide (Aβ) is the primary trigger for neuronal loss specific to this pathology. In healthy brain, Aβ levels are regulated by a dynamic equilibrium between Aβ release from the amyloid precursor protein (APP) and its removal by perivascular drainage or by amyloid-degrading enzymes (ADEs). During the last decade, the ADE family was fast growing, and currently it embraces more than 20 members. There are solid data supporting involvement of each of them in Aβ clearance but a zinc metallopeptidase neprilysin (NEP) is considered as a major ADE. NEP plays an important role in brain function due to its role in terminating neuropeptide signalling and its decrease during ageing or after such pathologies as hypoxia or ischemia contribute significantly to the development of AD pathology. The recently discovered mechanism of epigenetic regulation of NEP by the APP intracellular domain (AICD) opens new avenues for its therapeutic manipulation and raises hope for developing preventive strategies in AD. However, consideration needs to be given to the diverse physiological roles of NEP. This paper critically evaluates general biochemical and physiological functions of NEP and their therapeutic relevance.

The early stages of Alzheimer's disease are characterized by cholinergic deficits and the preservation of cholinergic function through the use of acetylcholinesterase inhibitors is the basis for current treatments of the disease. Understanding the causes for the loss of basal forebrain cholinergic neurons in neurodegeneration is therefore a key to developing new therapeutics. In this study, we review novel aspects of cholinesterase membrane localization in brain and propose mechanisms for its lipid domain targeting, secretion and protein-protein interactions. In erythrocytes, acetylcholinesterase (AChE) is localized to lipid rafts through a GPI anchor. However, the main splice form of AChE in brain lacks a transmembrane peptide anchor region and is bound to the 'proline-rich membrane anchor', PRiMA, in lipid rafts. Furthermore, AChE is secreted ('shed') from membranes and this shedding is stimulated by cholinergic agonists. Immunocytochemical studies on rat brain have shown that membrane-associated PRiMA immunofluorescence is located selectively at cholinergic neurons of the basal forebrain and striatum. A strong association of AChE with the membrane via PRiMA seems therefore to be a specific requirement of forebrain cholinergic neurons. α7 nicotinic acetylcholine receptors are also associated with lipid rafts where they undergo rapid internalisation on stimulation. We are currently probing the mechanism(s) of AChE shedding, and whether this process and its apparent association with α7 nicotinic acetylcholine receptors and metabolism of the Alzheimer's amyloid precursor protein is determined by its association with lipid raft domains either in normal or pathological situations., (© 2011 The Authors. Journal of Neurochemistry © 2011 International Society for Neurochemistry.)

Amyloidogenic processing of the amyloid precursor protein (APP) by β- and γ-secretases generates several biologically active products, including amyloid-β (Aβ) and the APP intracellular domain (AICD). AICD regulates transcription of several neuronal genes, especially the Aβ-degrading enzyme, neprilysin (NEP). APP exists in several alternatively spliced isoforms, APP(695), APP(751), and APP(770). We have examined whether each isoform can contribute to AICD generation and hence up-regulation of NEP expression. Using SH-SY5Y neuronal cells stably expressing each of the APP isoforms, we observed that only APP(695) up-regulated nuclear AICD levels (9-fold) and NEP expression (6-fold). Increased NEP expression was abolished by a β- or γ-secretase inhibitor but not an α-secretase inhibitor. This correlated with a marked increase in both Aβ(1-40) and Aβ(1-42) in APP(695) cells as compared with APP(751) or APP(770) cells. Similar phenomena were observed in Neuro2a but not HEK293 cells. SH-SY5Y cells expressing the Swedish mutant of APP(695) also showed an increase in Aβ levels and NEP expression as compared with wild-type APP(695) cells. Chromatin immunoprecipitation revealed that AICD was associated with the NEP promoter in APP(695), Neuro2a, and APP(Swe) cells but not APP(751) nor APP(770) cells where AICD was replaced by histone deacetylase 1 (HDAC1). AICD occupancy of the NEP promoter was replaced by HDAC1 after treatment of the APP(695) cells with a β- but not an α-secretase inhibitor. The increased AICD and NEP levels were significantly reduced in cholesterol-depleted APP(695) cells. In conclusion, Aβ and functional AICD appear to be preferentially synthesized through β-secretase action on APP(695).

In the central nervous system, acetylcholinesterase (AChE) is present in a tetrameric form that is anchored to membranes via a proline-rich membrane anchor (PRiMA). Previously it has been found that principal cholinergic neurons in the brain express high concentrations of AChE enzymic activity at their neuronal membranes. The aim of this study was to use immunocytochemical methods to determine the distribution of PRiMA in these neurons in the rat brain. Confocal laser and electron microscopic investigations showed that PRiMA immunoreactivity is associated with the membranes of the somata, dendrites and axons of cholinergic neurons in the basal forebrain, striatum and pedunculopontine nuclei, i.e. the neurons that innervate forebrain and brainstem structures. In these neurones, PRiMA also co-localizes with AChE immunoreactivity at the plasma membrane. PRiMA label was absent from neighboring GABAergic neurons, and from other neurons of the brain known to express high levels of AChE enzymic activity including cranial nerve motor neurons and dopaminergic neurons of the substantia nigra zona compacta. A strong association of AChE with PRiMA at the plasma membrane is therefore a feature specific to principal cholinergic neurons that innervate the central nervous system., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)