Upregulation Of Acetylcholinesterase Research Articles

Combined Exposure to Chronic Sleep Deprivation and Caffeine Potentiates Behavioural Deficits by Altering Neurochemical Profile and Synaptophysin Expression in Long-Evans Rats.

Using the Unpredictable Chronic Sleep Deprivation (UCSD) paradigm we developed, the combined effects of chronic sleep deprivation and high caffeine intake on prefrontal cortical synaptophysin expression, neurochemical profiles, and behavioural outcomes in Long-Evans rats were evaluated. The combination of chronic sleep deprivation and high-dose caffeine treatment produced varying degrees of behavioural impairments, depletion of antioxidants, serotonin, and an upregulation of acetylcholinesterase (AChE) activity in the prefrontal cortex. An immunohistochemical assessment revealed a reduction in synaptophysin protein expression in the prefrontal cortex following exposure to high-dose caffeine and chronic sleep deprivation. Overall, our findings support the advocacy for adequate sleep for optimal mental performance as a high intake of caffeine to attenuate the effects of sleep deprivation that may alter the neurochemical profile and synaptic plasticity in the prefrontal cortex, significantly increasing the risk of neuropsychiatric/degenerative disorders.

Exploring the neurogenic differentiation of human dental pulp stem cells.

Human dental pulp stem cells (hDPSCs) have increasingly gained interest as a potential therapy for nerve regeneration in medicine and dentistry, however their neurogenic potential remains a matter of debate. This study aimed to characterize hDPSC neuronal differentiation in comparison with the human SH-SY5Y neuronal stem cell differentiation model. Both hDPSCs and SH-SY5Y could be differentiated to generate typical neuronal-like cells following sequential treatment with all-trans retinoic acid (ATRA) and brain-derived neurotrophic factor (BDNF), as evidenced by significant expression of neuronal proteins βIII-tubulin (TUBB3) and neurofilament medium (NF-M). Both cell types also expressed multiple neural gene markers including growth-associated protein 43 (GAP43), enolase 2/neuron-specific enolase (ENO2/NSE), synapsin I (SYN1), nestin (NES), and peripherin (PRPH), and exhibited measurable voltage-activated Na+ and K+ currents. In hDPSCs, upregulation of acetylcholinesterase (ACHE), choline O-acetyltransferase (CHAT), sodium channel alpha subunit 9 (SCN9A), POU class 4 homeobox 1 (POU4F1/BRN3A) along with a downregulation of motor neuron and pancreas homeobox 1 (MNX1) indicated that differentiation was more guided toward a cholinergic sensory neuronal lineage. Furthermore, the Extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor U0126 significantly impaired hDPSC neuronal differentiation and was associated with reduction of the ERK1/2 phosphorylation. In conclusion, this study demonstrates that extracellular signal-regulated kinase/Mitogen-activated protein kinase (ERK/MAPK) is necessary for sensory cholinergic neuronal differentiation of hDPSCs. hDPSC-derived cholinergic sensory neuronal-like cells represent a novel model and potential source for neuronal regeneration therapies.

Retraction.

Retraction: "Upregulation of acetylcholinesterase caused by downregulation of microRNA-132 is responsible for the development of dementia after ischemic stroke," by Fu-wei Yang, Hao Wang, Chen Wang, and Guo-nan Chi, J Cell Biochem. 2020; 135-141: The above article, published online on 2 October 2019 in Wiley Online Library (https://onlinelibrary.wiley.com/doi/10.1002/jcb.28985) has been retracted by agreement between the authors, the journal's Editor in Chief, Prof. Dr. Christian Behl, and Wiley Periodicals LLC. The retraction has been agreed after the authors stated that the experimental data in the article could not be reproduced. Thus, the conclusions are considered to be invalid. The authors were not available for a final confirmation of the retraction.

Upregulation of acetylcholinesterase caused by downregulation of microRNA-132 is responsible for the development of dementia after ischemic stroke.

MicroRNA-132 (miR-132) has been shown to participate in many diseases. This study aimed to understand the correlation between the level of miR-132 and the severity of dementia post-ischemic stroke. An online tool (www.mirdb.org) was used to find the miR-132 binding site in acetylcholinesterase (ACHE) 3'-untranslated region (UTR), followed by a luciferase reporter assay to validate ACHE as a miR-132 target. A similar relationship between miR-132 and ACHE was also established in cerebrospinal fluid samples collected from human subjects. A negative correlation was established between ACHE and miR-132 by measuring the relative luciferase activity. Meanwhile, Western blot analysis and real-time polymerase chain reaction were also conducted to compare the levels of ACHE messenger RNA and protein between two groups (dementia positive, n = 26 and dementia negative, n = 26) or among cells treated with miR-132 mimics, ACHE small interfering RNA, and miR-132 inhibitors. As shown in the results, miR-132 can reduce the expression of ACHE. Further experiments were also carried out to study the effect of miR-132 and ACHE on cell viability and apoptosis, and the results demonstrated that miR-132 enhanced cell viability while suppressing apoptosis. In addition, ACHE reduced cell viability while promoting apoptosis. miR-132 targeted ACHE and suppressed its expression. Additionally, miR-132 and ACHE have been shown to affect the cell viability and apoptosis in the central nervous system.

Comparative analyses of the neurobehavioral, molecular, and enzymatic effects of organophosphates on embryo-larval zebrafish (Danio rerio)

Organophosphates insecticides (OPs) are common surface water contaminants in both urban and agricultural landscapes. Neurobehavioral effects on larval fish are known to occur at concentrations higher than those reported in the environment. The aim of this study was to perform a comparative analysis of neurobehavioral, molecular, and biochemical responses of four OPs (diazinon, dichlorvos, malathion, methyl-parathion) via the following endpoint measurements: distance traveled, velocity, gene expression (AChE, c-Fos, LINGO-1B, GRIN-1B), enzymatic acetylcholinesterase (AChE) activity, and carboxylesterase (CES) activity. OP exposures (5 hpf - 120 dpf) on embryo-larval zebrafish (Danio rerio) were assessed using a larval zebrafish behavior assay at concentrations: 0.01, 0.1, 10, and 100 μg/L. Individual OPs had varying degrees of neurotoxicity. Significant hypoactivity was observed in the 100 μg/L treatments for diazinon and malathion (p < 0.05) as compared to the controls. Diazinon-exposed larvae exhibited a 26% locomotor decrease, and hypoactivity was observed in malathion-exposed larvae at a reduction of 22% and 29% for distance traveled and velocity, respectively. Gene regulation and enzymatic activity changes were measured for both 0.1 and 100 μg/L exposures across OP treatments. Increased CES activity was observed for the 0.1 μg/L treatments of diazinon and methyl-parathion as well as the 100 μg/L treatment of dichlorvos; meanwhile, decreased CES activity was observed for 100 μg/L treatments of diazinon and malathion. Relative enzymatic activity of AChE was inhibited as compared to the control for the 0.1 μg/L diazinon. No other treatment group exhibited a significant effect on biochemical AChE activity; however, AChE upregulation was observed in the 0.1 μg/L exposure for diazinon, dichlorvos, and malathion. Methyl-parathion was observed to downregulate c-Fos at 0.1 μg/L exposure. Malathion upregulated LINGO-1B at 100 μg/L, a gene associated with neuronal regeneration; meanwhile, downregulation of LINGO-1B was observed for 0.1 μg/L exposure of methyl-parathion. Additional downregulation was observed for GRIN-1B in the 100 μg/L diazinon, 100 μg/L dichlorvos, and 0.1 μg/L methyl-parathion treatments. Exposure of ZF embryos to independent concentrations of 100 μg/L concentrations of diazinon and malathion resulted in hypoactivity and decreased CES activity at 5 dfp. No changes in swimming behavior were observed for either the 0.1 μg/L or 100 μg/L dichlorvos or methyl-parathion treatments. Observations from this study indicate that AChE inhibition may not be the most sensitive biomarker of OP pesticide exposure in zebrafish. Rather, the enzyme CES demonstrated higher sensitivity as a biomarker of OP toxicity.

Cholinergic and adenosinergic systems exert a pro-inflammatory profile in peripheric and splenic lymphocytes of Rhamdia quelen experimentally infected by Aeromonas caviae

It has been recognized that the cholinergic and adenosinergic systems, through the enzymes acetylcholinesterase (AChE) and adenosine deaminase (ADA), exert an important role in the immune and inflammatory responses during bacterial fish diseases. The immune response against Aeromonas caviae remains poorly understood, and the involvement of these systems, through the anti-inflammatory molecules acetylcholine (ACh) and adenosine (Ado), has not been studied. Thus, the aim of this study was to evaluate the involvement of cholinergic and adenosinergic systems on the inflammatory and immune responses in peripheric and splenic lymphocytes of fish experimentally infected with A. caviae. AChE and ADA activities in peripheric and splenic lymphocytes increased in infected animals on day 4 post-infection compared to uninfected animals, while the ACh and Ado levels decreased. Moreover, spleen histopathology revealed an increase in the number of melano-macrophage centers, as well as lipid inclusions and cellular debris in the ellipsoids. This evidence indicates that infection by A. caviae alters the cholinergic and adenosinergic systems, suggesting the involvement of AChE and ADA activities in the impairment of the immune system, since infection leads to a reduction in ACh and Ado levels, respectively. In summary, the upregulation of AChE and ADA activities in peripheric and splenic lymphocytes exerts a pro-inflammatory profile, contributing to systemic and tissue inflammatory damage, and consequently to disease pathogenesis.

Involvement of the Septo-Hippocampal Cholinergic Pathway in Association with Septal Acetylcholinesterase Upregulation in a Mouse Model of Tauopathy.

Cholinergic cell loss in the basal forebrain, the major source of hippocampal cholinergic projections, has been implicated in Alzheimer's disease. To examine whether the septohippocampal pathway is involved in tauopathy model mice and to elucidate the tau-associated mechanism underlying cholinergic alteration. Adult (6 to 8 months old) and old (16 to 18 months old) transgenic mice expressing wild-type human tau, Tg601, were examined using Ex vivo diffusion tensor magnetic resonance imaging (DTI) and 2-[18F]fluoro- 2-deoxy-D-glucose positron emission tomography (FDG-PET). Choline acetyltransferase (ChAT)-positive neurons in the medial septum (MS) were counted by stereological methods. Acetylcholinesterase (AChE) activity and AChE mRNA in 6 brain regions were measured. Ex vivo DTI revealed that the number of fractional anisotropy (FA) streamlines in the septohippocampal tract decreased with age in Tg601 mice. The FA value in the septum was lower in old Tg601 mice than in non-tg mice. A voxel-based statistical analysis of FDG-PET revealed the presence of low glucose uptake areas, involving the MS in adults, and spread over regions including the hippocampal dentate gyrus in old mice. In the MS, the number of choline acetyltransferase (ChAT)-positive neurons decreased in old Tg601 mice. AChE activity and AChE mRNA T transcripts were exclusively higher in the septum. The upregulation of AChE in the septum may result in the selective degeneration of the septohippocampal cholinergic pathway in the tauopathy mouse model.

MRNA Levels of ACh-Related Enzymes in the Hippocampus of THY-Tau22 Mouse: A Model of Human Tauopathy with No Signs of Motor Disturbance.

The microtubule-associated protein Tau tends to form aggregates in neurodegenerative disorders referred to as tauopathies. The tauopathy model transgenic (Tg) THY-Tau22 (Tau22) mouse shows disturbed septo-hippocampal transmission, memory deficits and no signs of motor dysfunction. The reports showing a hippocampal downregulation of choline acetyltransferase (ChAT) in SAMP8 mice, a model of aging, and an upregulation of acetylcholinesterase (AChE) in Tg-VLW mice, a model of FTDP17 tauopathy, may lead to think that the supply of ACh to the hippocampus can be threatened as aging or Tau pathology progress. The above was tested by comparing the mRNA levels for ACh-related enzymes in hippocampi of wild-type (wt) and Tau22 mice at ages when the neuropathological signs are debuting (3-4 months), moderate (6-7 months) and extensive (>9 months). Age-matched Tau22 and wt mice hippocampi displayed similar ChAT, AChE-T, butyrylcholinesterase (BChE) and a proline-rich membrane anchor (PRiMA) mRNA levels, any change most likely arising from ACh homeostasis. The unchanged hippocampal levels of AChE-T mRNA and enzyme activity observed in Tau22 mice, expressing G272V-P301S hTau, differed from the increase in AChE-T mRNA and activity observed in Tg-VLW mice, expressing G272V-P301L-R406W hTau. The difference supports the idea that AChE upregulation may proceed or not depending on the particular Tau mutation, which would dictate Tau folding, the accessibility/affinity to kinases and phosphatases, and P-Tau aggregation with itself and protein partners, transcription factors included.

Subchronic treatment of donepezil rescues impaired social, hyperactive, and stereotypic behavior in valproic acid-induced animal model of autism.

Autism spectrum disorder (ASD) is a group of pervasive developmental disorders with core symptoms such as sociability deficit, language impairment, and repetitive/restricted behaviors. Although worldwide prevalence of ASD has been increased continuously, therapeutic agents to ameliorate the core symptoms especially social deficits, are very limited. In this study, we investigated therapeutic potential of donepezil for ASD using valproic acid-induced autistic animal model (VPA animal model). We found that prenatal exposure of valproic acid (VPA) induced dysregulation of cholinergic neuronal development, most notably the up-regulation of acetylcholinesterase (AChE) in the prefrontal cortex of affected rat and mouse offspring. Similarly, differentiating cortical neural progenitor cell in culture treated with VPA showed increased expression of AChE in vitro. Chromatin precipitation experiments revealed that acetylation of histone H3 bound to AChE promoter region was increased by VPA. In addition, other histone deacetyalse inhibitors (HDACIs) such as trichostatin A and sodium butyrate also increased the expression of AChE in differentiating neural progenitor cells suggesting the essential role of HDACIs in the regulation of AChE expression. For behavioral analysis, we injected PBS or donepezil (0.3 mg/kg) intraperitoneally to control and VPA mice once daily from postnatal day 14 all throughout the experiment. Subchronic treatment of donepezil improved sociability and prevented repetitive behavior and hyperactivity of VPA-treated mice offspring. Taken together, these results provide evidence that dysregulation of ACh system represented by the up-regulation of AChE may serve as an effective pharmacological therapeutic target against autistic behaviors in VPA animal model of ASD, which should be subjected for further investigation to verify the clinical relevance.

Acetylcholinesterase loosens the brain's cholinergic anti-inflammatory response and promotes epileptogenesis

Recent studies show a key role of brain inflammation in epilepsy. However, the mechanisms controlling brain immune response are only partly understood. In the periphery, acetylcholine (ACh) release by the vagus nerve restrains inflammation by inhibiting the activation of leukocytes. Recent reports suggested a similar anti-inflammatory effect for ACh in the brain. Since brain cholinergic dysfunctions are documented in epileptic animals, we explored changes in brain cholinergic gene expression and associated immune response during pilocarpine-induced epileptogenesis. Levels of acetylcholinesterase (AChE) and inflammatory markers were measured using real-time RT-PCR, in-situ hybridization and immunostaining in wild type (WT) and transgenic mice over-expressing the “synaptic” splice variant AChE-S (TgS). One month following pilocarpine, mice were video-monitored for spontaneous seizures. To test directly the effect of ACh on the brain's innate immune response, cytokines expression levels were measured in acute brain slices treated with cholinergic agents. We report a robust up-regulation of AChE as early as 48 h following pilocarpine-induced status epilepticus (SE). AChE was expressed in hippocampal neurons, microglia, and endothelial cells but rarely in astrocytes. TgS mice overexpressing AChE showed constitutive increased microglial activation, elevated levels of pro-inflammatory cytokines 48 h after SE and accelerated epileptogenesis compared to their WT counterparts. Finally we show a direct, muscarine-receptor dependant, nicotine-receptor independent anti-inflammatory effect of ACh in brain slices maintained ex vivo. Our work demonstrates for the first time, that ACh directly suppresses brain innate immune response and that AChE up-regulation after SE is associated with enhanced immune response, facilitating the epileptogenic process. Our results highlight the cholinergic system as a potential new target for the prevention of seizures and epilepsy.

Cholinergic status modulations in human volunteers under acute inflammation

Cholinergic Status, the total soluble circulation capacity for acetylcholine hydrolysis, was tested for putative involvement in individual variabilities of the recruitment of immune cells in response to endotoxin challenge. Young (average age 26) and elderly (average age 70) volunteers injected with either Escherichia coli endotoxin or saline on two different occasions were first designated Enhancers and Suppressors if they showed increase or decrease, respectively, in plasma acetylcholinesterase (AChE) activity 1.5 h after endotoxin administration compared to saline. Enhancers showed significant co-increases in plasma butyrylcholinesterase (BChE) and paraoxonase (PON1) activities, accompanied by rapid recovery of lymphocyte counts. Young Enhancers alone showed pronounced post-exposure increases in the pro-inflammatory cytokine interleukin-6 (IL-6), and upregulation of the normally rare, stress-induced AChE-R variant, suggesting age-associated exhaustion of the cholinergic effects on recruiting innate immune reactions to endotoxin challenge. Importantly, IL-6 injected to young volunteers or administered in vitro to primary mononuclear blood cells caused upregulation of AChE, but not BChE or PON1, excluding it from being the sole cause for this extended response. Interestingly, Suppressors but not Enhancers showed improved post-exposure working memory performance, indicating that limited cholinergic reactions may be beneficial for cognition. Our findings establish Cholinergic Status modulations as early facilitators and predictors of individual variabilities in the peripheral response to infection.