Cerebrospinal Fluid Acetylcholinesterase Activity Research Articles

CSF and Plasma Cholinergic Markers in Patients With Cognitive Impairment.

IntroductionAlzheimer’s disease (AD) is the most prevalent form of dementia with symptoms of deteriorating cognitive functions and memory loss, partially as a result of a decrease in cholinergic neurotransmission. The disease is incurable and treatment with cholinesterase inhibitors (ChEIs) is symptomatic. Choline acetyltransferase (ChAT), the enzyme that synthesizes acetylcholine (ACh), has been proven recently to be present in both cerebrospinal fluid (CSF) and plasma. As ChAT plays a role in regulating the extracellular ACh levels, it may have an impact on prognosis and cognitive performance in AD patients.ObjectivesTo measure ChAT activity and its protein concentration in CSF and plasma from patients with AD, mild cognitive impairment (MCI), or Subjective cognitive impairment (SCI).MethodsPlasma and CSF samples were obtained from 21 AD, 32 MCI, and 30 SCI patients. The activity and protein levels of ChAT and acetylcholinesterase (AChE), the enzyme catalyzing the hydrolysis of ACh, were analyzed using an integrated activity and protein concentration ELISA-like assay. A Cholinergic Index was calculated as the ratio of ChAT to AChE activities in CSF. The data were analyzed in relation to dementia biomarkers and cognitive performance of the patients.ResultsThe CSF ChAT activity was significantly higher (55–67%) in MCI patients compared to AD and SCI cases. The CSF Cholinergic Index was 41 and 22% lower in AD patients than in MCI and SCI subjects, respectively. This index correlated positively with the Aβ42/p-tau ratio in CSF in SCI but negatively with that in AD and MCI. The ChAT activity and protein levels in plasma exhibited significant differences with the pattern of AD>>MCI>SCI.ConclusionThis is the first study investigating soluble levels of the key cholinergic enzyme, ChAT, in both plasma and CSF of individuals at different clinical stages of dementia. Although further validation is needed, the overall pattern of the results suggests that in the continuum of AD, the cholinergic signaling exhibits an inverse U-shape dynamic of changes in the brain that greatly differs from the changes observed in the plasma compartment.

Cerebrospinal Fluid (CSF) 25-Hydroxyvitamin D Concentration and CSF Acetylcholinesterase Activity Are Reduced in Patients with Alzheimer's Disease

BackgroundLittle is known of vitamin D concentration in cerebrospinal fluid (CSF) in Alzheimer´s disease (AD) and its relation with CSF acetylcholinesterase (AChE) activity, a marker of cholinergic function.MethodsA cross-sectional study of 52 consecutive patients under primary evaluation of cognitive impairment and 17 healthy controls. The patients had AD dementia or mild cognitive impairment (MCI) diagnosed with AD dementia upon follow-up (n = 28), other dementias (n = 12), and stable MCI (SMCI, n = 12). We determined serum and CSF concentrations of calcium, parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHD), and CSF activities of AChE and butyrylcholinesterase (BuChE). FindingsCSF 25OHD level was reduced in AD patients (P < 0.05), and CSF AChE activity was decreased both in patients with AD (P < 0.05) and other dementias (P < 0.01) compared to healthy controls. None of the measured variables differed between BuChE K-variant genotypes whereas the participants that were homozygous in terms of the apolipoprotein E (APOE) ε4 allele had decreased CSF AChE activity compared to subjects lacking the APOE ε4 allele (P = 0.01). In AD patients (n=28), CSF AChE activity correlated positively with CSF levels of total tau (T-tau) (r = 0.44, P < 0.05) and phosphorylated tau protein (P-tau) (r = 0.50, P < 0.01), but CSF activities of AChE or BuChE did not correlate with serum or CSF levels of 25OHD.ConclusionsIn this pilot study, both CSF 25OHD level and CSF AChE activity were reduced in AD patients. However, the lack of correlations between 25OHD levels and CSF activities of AChE or BuChE might suggest different mechanisms of action, which could have implications for treatment trials.

Changes in CSF acetyl- and butyrylcholinesterase activity after long-term treatment with AChE inhibitors in Alzheimer’s disease

To measure cerebrospinal fluid (CSF) activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in patients with Alzheimer's disease (AD) participating in randomized clinical trials from three European centers, before and after long-term treatment with different AChE inhibitors (AChEIs). Of the 144 patients included in the study, 104 were treated with donepezil, 15 with galantamine, 16 with rivastigmine, and nine with placebo. CSF AChE and BChE activities were measured at baseline and after 1- year treatment. Donepezil and galantamine groups showed a significant increase in CSF AChE activity at follow-up, while no changes for BChE activity were observed; in donepezil group, a positive correlation between plasma concentration and AChE activity was documented. Conversely, in rivastigmine group, a decrease in CSF activity of both enzymes was observed. CSF AChE and BChE activities were not correlated with the clinical outcome in any group considered. CSF biomarkers did not show any change after treatment. AChEIs differently influence the activity of target enzymes in CSF independent of their pharmacodynamic effects.

Acetylcholinesterase activities in cerebrospinal fluid of patients with senile dementia of Alzheimer type.

We have studied, as a possible marker of cholinergic neurons, the acetylcholinesterase (AChE) activity in cerebrospinal fluid (CSF) of 21 SDA patients and 9 controls of similar age with no neurological disease. The AChE activities were significantly lower in the SDA patients compared to the controls. The AChE activities were also lowered in the most severely demented patients compared to those who were less severely demented but the difference was not statistically significant. As a potential glia marker, beta-glucuronidase activity in CSF was studied, but no significant difference was found in the activities of the SDA patients compared to the controls. The reduced AChE activities in the CSF of the SDA patients may be related to the loss of cholinergic neurons or disturbed cholinergic metabolism in the brain.

Cerebrospinal fluid acetylcholinesterase activity after long-term treatment with donepezil and rivastigmina

At present acetylcholinesterase (AChE) inhibitors (AChEIs) represent the only reliable therapeutic resource for symptomatic treatment of Alzheimer Disease (AD). This study was designed to assess the effects of 6–12 month treatment with AChEIs donepezil and rivastigmine on cerebrospinal fluid (CSF) AChE and butyrylcholinesterase (BuChE) activity in AD patients. The pattern of AChE isoforms (G4, G1, G2) before and after treatment was investigated as well. In AD patients treated with donepezil a significant increase of CFS AChE activity was observed, whereas treatment with rivastigmine induced a significant decrease of AChE activity. Both drugs did not change BuChE activity and tended to restore the physiological pattern of AChE isoform. The possible significance of the influence of AChEIs on CSF AChE activity and isoforms is discussed.

Acetylcholinesterase assay for cerebrospinal fluid using bupivacaine to inhibit butyrylcholinesterase

BackgroundMost test systems for acetylcholinesterase activity (E.C.3.1.1.7.) are using toxic inhibitors (BW284c51 and iso-OMPA) to distinguish the enzyme from butyrylcholinesterase (E.C.3.1.1.8.) which occurs simultaneously in the cerebrospinal fluid. Applying Ellman's colorimetric method, we were looking for a non-toxic inhibitor to restrain butyrylcholinesterase activity. Based on results of previous in vitro studies bupivacaine emerged to be a suitable inhibitor.ResultsPharmacokinetic investigations with purified cholinesterases have shown maximum inhibition of butyrylcholinesterase activity and minimal interference with acetylcholinesterase activity at bupivacaine final concentrations between 0.1 and 0.5 mmol/l. Based on detailed analysis of pharmacokinetic data we developed three equations representing enzyme inhibition at bupivacaine concentrations of 0.1, 0.2 and 0.5 mmol/l. These equations allow us to calculate the acetylcholinesterase activity in solutions containing both cholinesterases utilizing the extinction differences measured spectrophotometrically in samples with and without bupivacaine. The accuracy of the bupivacaine-inhibition test could be confirmed by investigations on solutions of both purified cholinesterases and on samples of human cerebrospinal fluid. If butyrylcholinesterase activity has to be assessed simultaneously an independent test using butyrylthiocholine iodide as substrate (final concentration 5 mmol/l) has to be conducted.ConclusionsThe bupivacaine-inhibition test is a reliable method using spectrophotometrical techniques to measure acetylcholinesterase activity in cerebrospinal fluid. It avoids the use of toxic inhibitors for differentiation of acetylcholinesterase from butyrylcholinesterase in fluids containing both enzymes. Our investigations suggest that bupivacaine concentrations of 0.1, 0.2 or 0.5 mmol/l can be applied with the same effect using 1 mmol/l acetylthiocholine iodide as substrate.

Preferential cerebrospinal fluid acetylcholinesterase inhibition by rivastigmine in humans.

This study sought to examine the feasibility of prolonged assessment of acetylcholinesterase (AChE) activity in the cerebrospinal fluid (CSF) of volunteers and to test the hypothesis that rivastigmine (ENA-713; Exelon, Novartis Pharma AG, Basel, Switzerland) selectively inhibits AChE in CSF in humans at a dose producing minimal inhibition of the peripheral enzyme. Lumbar CSF samples were collected continuously (0.1 mL x min(-1)) for 49 hours from eight healthy volunteers who took either placebo or a single oral dose of rivastigmine (3 mg). CSF specimens and samples of blood cells and blood plasma were analyzed at intervals for rivastigmine and its metabolite NAP 226-90 ([-] [3-([1-dimethylaminolethyl)-phenol]), erythrocyte AChE activity, CSF AChE activity, and plasma and CSF butyrylcholinesterase (BuChE) activity. Safety evaluations were performed 23 hours after drug dosing and at the end of the study. Evaluable data were obtained from six subjects. The mean time to maximal rivastigmine plasma concentration (tmax) was 0.83 +/- 0.26 hours, the mean maximal plasma concentration (Cmax) was 4.88 +/- 3.82 ng x mL(-1), the mean plasma area under the concentration versus time curve (AUC0-infinity) was 7.43 +/- 4.74 ng x hr x mL(-1), and the mean plasma t1/2 was 0.85 +/- 0.115 hours. The concentration of rivastigmine in CSF was lower than the quantification limit for assay (0.65 ng x mL(-1)), but NAP 226-90 reached a mean Cmax of 3.14 +/- 0.57 ng x mL(-1). Only minimal inhibition of erythrocyte AChE activity (approximately 3%) was observed. Inhibition of AChE in the CSF after rivastigmine administration was significantly greater than after placebo for up to 8.4 hours after the dose and was maximal (40%) at 2.4 hours. Plasma BuChE activity was significantly lower after rivastigmine than after placebo, but this was not clinically relevant. BuChE activity in CSF was significantly lower after rivastigmine than after placebo for up to 3.6 hours after dosing, but this difference was not sustained. This study confirms the feasibility of using continuous measurement of AChE activity in CSF over prolonged periods, that rivastigmine markedly inhibits CSF AChE after a single oral dose of 3 mg, and that the inhibition of central AChE is substantially greater than that of peripheral AChE or BuChE.

Long-term tacrine treatment in three mild Alzheimer patients: effects on nicotinic receptors, cerebral blood flow, glucose metabolism, EEG, and cognitive abilities.

The effect of long-term treatment with tacrine (tetrahydroaminoacridine) was studied in three Alzheimer patients (aged 57, 64, and 68 years) with mild dementia. All three patients had a Mini-Mental State Examination score of 24/30 and carried at least one apolipoprotein E (ApoE) epsilon4 allele. Tacrine was given in doses between 80 and to 160 mg daily for 13-31 months. A lower tacrine concentration was observed generally in cerebrospinal fluid (CSF) compared with plasma. The acetylcholinesterase activity in CSF tended to be increased following longer periods of tacrine treatment, whereas the butyrylcholinesterase activity was decreased. The three patients repeatedly underwent positron emission tomography investigation of cerebral blood flow, nicotinic receptors, cerebral glucose metabolism, and electroencephalogram (EEG) and cognitive tests. Positive influences on these parameters were observed following both short-term and long-term treatment with tacrine. Improvement of nicotinic receptors (measured as 11C-nicotine binding), cerebral blood flow, EEG, and some cognitive tests (trail making test, block design test) occurred earlier after initiation of tacrine treatment compared with the glucose metabolism, which was increased after several months of tacrine treatment. An improvement in attention (trail making test) was observed following tacrine as sign for frontal lobe activation (EEG). The functional effects of tacrine in Alzheimer patients appeared to be related to both dose and length of cholinesterase inhibitor treatment.

Clinicobiochemical Evaluation of Ceruletide in Patients with Dementia of the Alzheimer Type

We evaluated the clinical effectiveness of ceruletide in patients with dementia of the Alzheimer type and its effects on neurotransmitters in cerebrospinal fluid. Mini mental state scores were significantly increased after ceruletide administration. Acetylcholinesterase activity in cerebrospinal fluid was significantly increased after administration, while somatostatin and monoamine metabolites showed no significant changes. Ceruletide improved intellectual function, and the improvement seemed to be due to activation of neurotransmitters in the acetylcholine system in the brain. Though the subjects were elderly patients, no side effects presenting clinical problems were observed. This warrants further detailed studies on the effectiveness of ceruletide in dementia of the Alzheimer type.

Cerebrospinal Fluid as a Reflector of Central Cholinergic and Amino Acid Neurotransmitter Activity in Cerebellar Ataxia

Cerebrospinal fluid (CSF) amino acid neurotransmitters, related compounds, and their precursors, choline levels, and acetylcholinesterase activity were measured in the CSF of patients with cerebellar ataxia during a randomized, double-blind, crossover, placebo-controlled clinical trial of physostigmine salicylate. The CSF gamma-aminobutyric acid, methionine, and choline levels, adjusted for age, were significantly lower in patients with cerebellar ataxia compared with controls. Physostigmine selectively reduced the level of CSF isoleucine and elevated the levels of phosphoethanolamine. No change occurred in CSF acetylcholinesterase activity and in the levels of plasma amino compounds in patients with cerebellar ataxia when compared with controls. Median ataxia scores did not statistically differ between placebo and physostigmine nor did functional improvement occur in any of the patients.

Activities and kinetic properties of lumbar cerebrospinal fluid cholinesterases in relation to clinical diagnosis, severity, and progression of Alzheimer's disease.

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities of lumbar cerebrospinal fluid (CSF) have been measured in seventeen patients with a clinical diagnosis of probable Alzheimer's disease (Prob AD), possible Alzheimer's disease (Poss AD), or dementia of non-Alzheimer aetiology (Non-AD). The three diagnostic groups did not differ with regard to the Km or saturation kinetic properties of AChE and BChE. The CSF AChE activity was significantly higher in Prob AD than in Non-AD patients. The groups did not differ significantly in BChE activity. The ratio of AChE to BChE activity was significantly higher in both the Prob AD and Poss AD groups than in the Non-AD group, and the ranges of values in the Prob AD and Non-AD groups did not overlap. Among patients in the Prob AD group, severity of dementia was correlated with both AChE activity and the AChE/BChE ratio, and progression of dementia over time was also correlated with AChE/BChE. The AChE/BChE ratio correlated more strongly than AChE with severity and progression of dementia in Prob AD patients, and also better distinguished them from Non-AD patients, suggesting that AChE/BChE may be the more useful marker for diagnosis of AD. It is not clear from the results whether AChE/BChE is useful for diagnosis of the complex dementia cases in the Poss AD group.

Cerebrospinal fluid cholinesterases in aging and in dementia of the Alzheimer type.

Protein concentration and acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were assayed in the cerebrospinal fluid (CSF) of 26 healthy normal subjects (20-86 years old), 27 patients with dementia of the Alzheimer type (DAT), and 10 patients with dementia of the Alzheimer type with extrapyramidal signs (EDAT). In normal subjects, there was an age-related increase in CSF protein and AChE activity and a significant correlation (p less than 0.001) between CSF protein and BChE activity. In the DAT and EDAT groups, CSF AChE activities (mean +/- SD = 17.5 +/- 3.6 and 15.3 +/- 4.4 nmol/min/ml, respectively) were significantly lower (p less than 0.05) than in 13 age-matched control subjects (21.5 +/- 5.6 nmol/min/ml). In contrast, neither CSF protein concentration, BChE activity, nor the ratio of AChE/BChE differed significantly between groups. In patients with DAT, CSF AChE activity was significantly lower (p less than 0.05) in subjects with an early onset compared to those with a late onset (16.4 +/- 3.4 and 19.7 +/- 2.8 nmol/min/ml, respectively), and activity in the latter group did not differ significantly from control values. CSF AChE activity was not related to dementia severity and did not change significantly over an 18-month period. Although these results confirm a cholinergic deficit in patients with DAT, the considerable overlap of CSF AChE activity between groups and the nonsignificant correlation between AChE activity and dementia severity limit the usefulness of CSF AChE as a diagnostic marker of this disorder.

Acetyl- and butyrylcholinesterase activity in the cerebrospinal fluid of patients with Parkinson's disease

In this study we investigated acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities and the molecular forms of these enzymes in the cerebrospinal fluid (CSF) of non-demented and demented Parkinsonian patients and in controls. The ratio of AChE to BChE activity was lower in the CSF of demented patients than in non-demented patients, although AChE and BChE activities and the molecular forms of AChE and BChE were the same in the different groups of patients. AChE activity in CSF did not vary according to the severity or duration of dementia associated with Parkinson's disease or with the disability stage of Parkinson's disease. BChE activity in CSF correlated with these clinical parameters, and patients with cerebral atrophy had higher BChE activity in CSF than those patients without atrophy. These alterations in the BChE activity of CSF may be related to gliosis which occurs in the degenerating brain tissue.

Acetylcholinesterase and butyrylcholinesterase activity in the cerebrospinal fluid of patients with neurodegenerative diseases involving cholinergic systems.

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) were assayed in the cerebrospinal fluid (CSF) of subjects with neurodegenerative diseases (dementing and non-dementing, with and without known cholinergic lesions), to determine whether CSF AChE is a valid marker of central cholinergic activity. The relative proportions of the different forms of each enzyme and of AChE to BChE were similar in CSF and brain. AChE decreased in Huntington's chorea (degeneration of striatal cholinergic interneurons) but also in multiple sclerosis (not known to affect cholinergic systems). BChE paralleled AChE, although the enzymes were dissociated in some patients. It is concluded that CSF AChE activity may globally reflect brain AChE, but pathology-induced changes may not be directly reflected.

Acetylcholinesterase activity in cerebrospinal fluid of patients with Alzheimer's disease and senile dementia

Acetylcholinesterase (AChE) in the cerebrospinal fluid (CSF) from patients with Alzheimer-type dementia and control subjects was analyzed by centrifugation on a sucrose density gradient, and by column chromatography on Sephadex G-200. The sedimentation coefficient and molecular weight of CSF AChE were calculated as 10S and 380 000, respectively, which corresponded to those of G4 isozyme in the brain. Other isozymes of AChE were not detected in the CSF of either patients with Alzheimer-type dementia or the controls. Sufficient activity of AChE was observed in the CSF of a patient with familial pseudocholinesterase deficiency, although the pseudocholinesterase activity was not found either in the serum or in the CSF. CSF AChE activity in control subjects increased with advancing age ( P < 0.02). AChE activity in the CSF was significantly lower in patients with presenile dementia (Alzheimer's disease), compared with age-matched control subjects ( P < 0.001). However, AChE activity in the CSF showed a wide variation among patients of Alzheimer-type dementia with a late onset (senile dementia).

Cerebral ventricular size and cerebrospinal fluid acetylcholinesterase levels in senile dementia of the Alzheimer type

Computed tomography (CT) was performed in 16 patients with a diagnosis of senile dementia of the Alzheimer type (SDAT). CT scans were rated without knowledge of clinical and laboratory data, and lateral ventricle-brain ratios (VBRs) calculated. Cerebrospinal fluid (CSF) acetylcholinesterase (AChE) activity was measured by radioenzymatic assay in all patients, and degree of dementia quantified using the Mini-Mental State Examination (MMSE). There were significant correlations between cerebral atrophy as assessed by VBR and CSF AChE activity. Cognitive impairment on MMSE also correlated significantly with VBR. These correlations were not accounted for by age, dilutional effects, or duration of illness. The relationship between VBR and AChE activity demonstrates an association between two independently determined pre-mortem measures of illness.

Somatostatin-like immunoreactivity and acetylcholinesterase activities in cerebrospinal fluid of patients with Alzheimer disease and senile dementia of the Alzheimer type

Somatostatin-like immunoreactivity (SLI) and acetylcholinesterase (AchE) activities were measured in the cerebrospinal fluid of 25 patients with senile dementia of the Alzheimer type (SDAT). Both SL1 levels and AchE activities were reduced in the CSF of SDAT patients. The SLI levels and AchE activities were not correlated with the duration and the dementia score. However, in two patients the CSF SLI concentration was in agreement with the SLI levels in the frontal cortex obtained by biopsy. Our findings suggest that CSF SLI may be a good index of cortical SLI activities.

Neurotransmitter-related enzymes in senile dementia of the alzheimer type

Choline acetyltransferase (ChAT), acetylcholinesterase (AChE) and glutamic acid decar☐ylase (GAD) activities were measured in 20 brain regions from autopsied control and senile dementia of the Alzheimer type (SDAT) cases. Large, widespread reductions in the activities of ChAT and AChE were found in tissues from SDAT cases, while GAD activities were reduced in 3 of the 20 regions investigated. AChE activity in cerebrospinal fluid from SDAT cases was similar to that found in samples from non-demented patients.