Acetylcholinesterase activity in ventricular and cisternal CSF of dogs: effect of chlorpromazine

Neuromodulatory and oxidative stress evaluations in African catfish Clarias gariepinus exposed to antipsychotic drug chlorpromazine

Chlorpromazine (CPZ) is among the most famous drugs used for the treatment of psychosis such as delusions, hallucinations, schizophrenia, paranoia, or disordered thought in humans. In the present study, the acetylcholinesterase (AChE) activity and oxidative stress parameters in the brain of Clarias gariepinus juveniles exposed to CPZ were investigated. Fish were exposed to 0.53, 1.56, and 2.11 mg/L corresponding to 5, 10, and 20% of the 96 h LC₅₀ of CPZ on C. gariepinus, respectively. The fish brain was sampled on days 1, 7, 14, and after 7-days recovery. Our results indicate that AChE values were significantly higher in exposed groups compared to the control on days 7, 14, and 7-days recovery. The values of lipid peroxidation (LPO), glutathione reductase (GR), and glutathione peroxidase (GPx) increased compared to the control while catalase (CAT) and superoxide dismutase (SOD) significantly declined at higher CBZ concentrations. While LPO and CAT returned to the same range as the control values after the 7-day withdrawal from the drug, AChE, SOD, GR, and GPx did not. The use and disposal of CPZ should be strictly regulated to avoid possible ecotoxicological impacts on non-target organisms.

Evaluation of ecotoxicological effects of drugs on Daphnia magna using different enzymatic biomarkers

The increasing occurrence of pharmaceutical drugs in the aquatic environment is cause of concern, due to the possibility of toxic phenomena in non-target species, including oxidative stress and neurotoxicity. The present study aimed to assess the acute effect of four widely used therapeutic agents: acetaminophen (analgesic), chlorpromazine (antipsychotic), diclofenac (anti-inflammatory) and propranolol (antihypertensive), in the cladoceran species Daphnia magna. Considering the involvement of the mentioned compounds in the impairment of cholinesterasic activity and modifications in cellular redox systems, the purpose of this study was to analyze their effects on biomarkers of neuronal regulation, such as total cholinesterases (ChEs), and enzymatic oxidative stress defense, including as catalase (CAT), glutathione-S-transferases (GSTs), and total and selenium-dependent glutathione-peroxidase (total GPx; Se-GPx) activities. Exposure to acetaminophen caused a significant inhibition of AChE and Se-GPx activities in D. magna relative to the control. Among the biomarkers of oxidative stress, only the activity of CAT was significantly altered in concentration of 0.001mg L(-1) of chlorpromazine, which was not always consistent with the literature. Diclofenac caused a significant inhibition of AChE and Se-dependent GPx, and also in total GPx activities. Propranolol was responsible for a significant decrease in the activity of the latter two enzymes, and also a slight increase of GSTs activity. The results indicated that the exposure to all the tested compounds induced alterations on the cellular redox status in the studied species. In addition, acetaminophen and diclofenac were shown to have the capability of interfering with D. magna neurotransmission, through the inhibition of ChEs. Our data enlighten the need for more research on the ecological consequences of pharmaceuticals in non-target organisms.

Acetylcholinesterase activity in the cerebrospinal fluid of dogs with seizures

Recent studies in animal models have focused on the role of cholinergic elements, mainly acetylcholinesterase (AChE) and the 'readthrough' acetylcholinesterase isoform (AChE-R), in seizures. A prospective double-masked study was conducted to assess the activity of AChE and AChE-R in cerebrospinal fluid (CSF) of 26 dogs post-seizure, 28 dogs with intervertebral disc disease (IVDD) and 16 healthy dogs. AChE was also measured in the serum in the post-seizure and IVDD groups. The results showed no significant differences in CSF AChE among the three groups. AChE-R was not detected in any dog and AChE in the serum was similar between groups. This preliminary study provides new information on AChE and AChE-R in the CSF and sera of dogs following naturally-occurring seizures.

Do cholinesterase inhibitors have disease-modifying effects in Alzheimer's disease?

During the last decade, a systematic effort to develop a pharmacological treatment for Alzheimer disease (AD) has resulted in drugs being registered for the first time in the US and Europe for this specific indication. The 3 agents registered are cholinesterase inhibitors (ChEIs). The major therapeutic effect of ChEIs in patients with AD is the maintenance of cognitive function, as compared with placebo, during a 6-month to 1-year period of treatment. Additional drug effects that may occur are the slowing of cognitive deterioration and improvement of behaviour and daily living activities. Comparison of clinical effects of 6 ChEIs demonstrates a rather similar magnitude of improvement in cognitive outcome measures. For some drugs, this level may represent an upper limit, while for others it may be possible to increase the benefit further. In order to maximise and prolong positive drug effects it is important to start treatment early and adjust the dosage during treatment. Recent studies that used this administration strategy have shown that in many patients, the stabilisation effect produced by ChEIs can be prolonged for as long as 36 months. This long-lasting effect suggests mechanisms of action other than symptomatic ones. In this article, the effects of ChEIs on beta-amyloid metabolism are postulated to explain the stabilising (i.e. disease-modifying) effects of the drugs. Evidence for such a mechanism is available at the experimental but not yet at the clinical level.

Is anti-cholinesterase therapy of Alzheimer's disease delaying progression?

During the last decade, a systematic effort to develop a pharmacological treatment for Alzheimer's disease (AD) resulted in three drugs being registered for the first time in the US and Europe. All three compounds are cholinesterase inhibitors (ChEI). The major therapeutic effect of ChEI on AD patients is to maintain cognitive function at a stable level during a 6-month to 1-year period of treatment, as compared to placebo. Additional drug effects are to slow down cognitive deterioration and improve behavioral and daily living activity. Recent studies show that in many patients the cognitive stabilization effect can be prolonged up to 24 months. This long-lasting effect suggests a mechanism of action other than symptomatic, and directly cholinergic. In vitro and in vivo studies have consistently demonstrated a link between cholinergic activation and amyloid precursor protein (APP) metabolism. Lesions of cholinergic nuclei cause a rapid increase in cortical APP and cholinergic synaptic function; the effect of such lesions can be reversed by ChEI treatment. A reduction in cholinergic neurotransmission, experimental or pathological, leads to amyloidogenic metabolism and contributes to the development of neuropathology and cognitive dysfunction. To explain the long-term effect of ChEI, for which evidence is available on an experimental as well as clinical level, a mechanism based on beta-amyloid metabolism is postulated. The question whether cholinergic stabilization implies simply slowing down progression of disability or also involves delay of disease progression is discussed.

Differential increase in cerebrospinal fluid-acetylcholinesterase after treatment with acetylcholinesterase inhibitors in patients with Alzheimer's disease

The clinical significance and the effects of pharmacological treatment of patients with Alzheimer's disease (AD) were evaluated by measurement of acetylcholinesterase (AChE) in the cerebrospinal fluid (CSF). CSF-AChE of AD patients was lower, not significantly, compared with controls. However, CSF-AChE was significantly increased after treatment of AD patients with AChE inhibitors (donepezil and galantamine). The increase was higher in patients treated with donezepil than in those treated with galantamine, which might be related to different mechanisms for the substances. The increase was also dose-dependent, and was especially marked in patients showing a clinical response. These data suggest that CSF biomarkers are capable not only of identifying a biochemical effect of drugs, but also of differentiating between different compounds in a dose-dependent manner.

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.

Diffuse transmission by acetylcholine in the CNS

Recent immunoelectron microscopic studies have revealed a low frequency of synaptic membrane differentiations on ACh (ChAT-immunostained) axon terminals (boutons or varicosities) in adult rat cerebral cortex, hippocampus and neostriatum, suggesting that, besides synaptic transmission, diffuse transmission by ACh prevails in many regions of the CNS. Cytological analysis of the immediate micro-environment of these ACh terminals, as well as currently available immunocytochemical data on the cellular and subcellular distribution of ACh receptors, is congruent with this view. At least in brain regions densely innervated by ACh neurons, a further aspect of the diffuse transmission paradigm is envisaged: the existence of an ambient level of ACh in the extracellular space, to which all tissue elements would be permanently exposed. Recent experimental data on the various molecular forms of AChE and their presumptive role at the neuromuscular junction support this hypothesis. As in the peripheral nervous system, degradation of ACh by the prevalent G4 form of AChE in the CNS would primarily serve to keep the extrasynaptic, ambient level of ACh within physiological limits, rather than totally eliminate ACh from synaptic clefts. Long-lasting and widespread electrophysiological effects imputable to ACh in the CNS might be explained in this manner. The notions of diffuse transmission and of an ambient level of ACh in the CNS could also be of clinical relevance, in accounting for the production and nature of certain cholinergic deficits and the efficacy of substitution therapies.

The significance of the activity of CSF cholinesterases in dementias

This article reviews the significance of changes in the level of cerebrospinal fluid acetylcholinesterase or cholinesterase in patients with Alzheimer's disease or other dementias. Evidence has shown that the methodology of assaying cerebrospinal fluid acetylcholinesterase or cholinesterase is reliable and the activity of the enzyme is stable. Low acetylcholinesterase or cholinesterase levels presenting in cerebrospinal fluid of a demented individual may confirm the clinical diagnosis of Alzheimer's disease or other organic dementia. A low activity of acetylcholinesterase or cholinesterase existing in cerebrospinal fluid of a non-demented individual may indicate a brain at risk, or that the person is in the preclinical stage of dementia. Recognition of the presence of the preclinical stage may be very beneficial for explaining the real meaning of the 'overlap' in the biochemistry and pathology between dementia and non-dementia, and also very important for prevention and treatment. Therefore, the strategy of prevention and of treatment should no longer be designed to inhibit acetylcholinesterase activity. In contrast, it should be designed to enhance the neuronal acetylcholinesterase activity or to delay the degeneration of brain acetylcholinesterase system.

Increased acetylcholinesterase activity in selected regions of rat brain after chronic (-)-deprenyl administration

(-)-Deprenyl, 0.05, 1.0, 2.0, and 10.0 mg/kg body weight, was administered intraperitonially to Wistar rats for 30 days. The activity of acetylcholinesterase, and monoamine oxidase A and B were assayed in different brain regions. After the experimental period acetyl cholinesterase activity was found to be significantly increased in frontal cortex [P < 0.001] and hippocampus [P < 0.001] but not in striatum and brainstem at 0.1, 1.0, and 2.0 mg/kg dose, the maximum increase being at 0.1 mg/kg dose. Monoamine oxidase B activity was inhibited by more than 90% at 1.0, 2.0, and 10.0 mg/kg dose while 0.05 and 0.1 dose inhibited only about 55% and 70% respectively. Monoamine oxidase A activity was inhibited to more than 70% at 1.0 mg dose and to more than 90% at 2.0 and 10.0 mg/kg dose. At 0.05 and 0.1 mg/kg dose monoamine oxidase A activity was not significantly altered.

Acetylcholine measurement of cerebrospinal fluid by in vivo microdialysis in freely moving rats

Acetylcholine (ACh) and choline (Ch) levels in rat cerebrospinal fluid (CSF) were determined by in vivo microdialysis (CSF microdialysis) in both halothane-anesthetized and freely-moving rats. The Ch/ACh ratio in CSF perfused with Ringer's solution (30 microliters/30 min) containing 10(-5) M physostigmine, a centrally active cholinesterase inhibitor, was significantly lower than that in unprocessed CSF due to significantly higher ACh levels in the former. The successive measurement on the 2nd and 7th day after the guide cannula implantation demonstrated the feasibility of the CSF microdialysis method for repetitive monitoring of CSF ACh and Ch levels in freely moving rats without extensive tissue damage. Intraperitoneal administration of physostigmine caused an increase in CSF ACh levels, whereas administration of neostigmine, which cannot penetrate into the blood brain barrier, did not. Furthermore, a centrally active acetylcholinergic M1-receptor agonist, AF102B, produced an increase in CSF ACh and Ch levels. Thus, the present study demonstrates that CSF microdialysis is a useful method for evaluating overall central cholinergic activity and investigating the pharmacological effects of various drugs that act via the central cholinergic system.

Stimulated release of acetylcholinesterase in rat striatum revealed by in vivo microspectrophotometry

The microspectrophotometric technique allows a direct in vivo measurement of brain extracellular acetylcholinesterase. An optical probe associated with electrodes for stimulation was implanted in striatum of anaesthetized rats to determine the effects of neuronal excitation on the acetylcholinesterase activity. Electrical stimulations induced a reversible increase in acetylcholinesterase activity of about 30 to 50%, with a recovery to baseline occurring after 1 or 2 h. Furthermore, iterative electrical stimulation induced a progressive fading of this phenomenon. An enhancement of acetylcholinesterase activity was also observed by stimulations with potassium injections through a canal of the probe. These results suggest mainly an intracellular origin of the released enzyme and estimate its contribution at about 40% of the whole extracellular enzyme activity.

Brain and cerebrospinal fluid cholinesterases in Alzheimer's disease, Parkinson's disease and aging. A critical review of clinical and experimental studies

Acetylcholinesterase (AChE), an enzyme responsible for the break-down of acetylcholine, is found both in cholinergic and non-cholinergic neurons in the central nervous system. In addition to its role in the catabolism of acetylcholine, AChE have other functions in brain, e.g. in the processing of peptides and proteins, and in the modulation of dopaminergic neurons in the brain stem. Several clinical and experimental studies have investigated AChE in brain and cerebrospinal fluid (CSF) in aging and dementia. The results suggest that brain AChE and its molecular forms show interesting changes in dementia and aging. However, CSF-AChE activity is not a very reliable or sensitive marker of the integrity and function of cholinergic neurons in the basal forebrain complex. Additional work is needed to clarify the role of AChE abnormality in the formation of pathology changes in patients with Alzheimer's disease.

Presence of a soluble form of acetylcholinesterase in human ocular fluids

Samples of ocular fluid obtained from normal persons at necropsy and during eye surgery have been assayed for the presence of acetylcholinesterase. Measurable levels could be detected in all samples examined, but levels of acetylcholinesterase in vitreous humour were consistently higher than those in aqueous humour, indicating a possible retinal origin. Polyacrylamide gel electrophoresis revealed that the enzyme of ocular fluid had the same mobility as that of acetylcholinesterase from cerebrospinal fluid. It is probable that acetylcholinesterase is secreted from neuronal structures in the retina into the ocular fluid in an analogous manner to the secretion of acetylcholinesterase from brain neurones into cerebrospinal fluid.

Cerebrospinal fluid choline levels are decreased in Parkinson's disease

We examined acetylcholinsterase (AChE) activity and choline levels in cerebrospinal fluid (CSF) in 16 patients with idiopathic Parkinson's disease and 9 control subjects of corresponding age: 8 were untreated Parkinson's patients; 4 were treated with carbidopa-levodopa (100/1,000 mg/day) for 20 +/- 3 months; and 4 were treated with carbidopa-levodopa (110/1,100 mg/day) for 28 +/- 18 months plus amantadine (200 mg/day) for 16 +/- 8 months. CSF choline levels (nmol/ml) were 2.97 +/- 0.79 (control subjects); 1.31 +/- 0.29 (untreated patients); 1.00 +/- 0.29 (carbidopa-levodopa treated); and 1.26 +/- 0.19 (carbidopa-levodopa/amantadine treated). Choline levels were significantly lower in untreated and treated patients compared to control subjects (p = 0.0001). AChE activity did not differ in Parkinson's disease patients as compared to control subjects. The reduced level of choline in CSF may reflect a deficit in choline transport into the brain or a decrease of choline-phospholipid output from the brain.

Cholinesterases in the cerebrospinal fluid, plasma, and erythrocytes of patients with Alzheimer's disease

In patients with probable Alzheimer's disease and in controls, acetyl- and butyrylcholinesterase activities were studied in cerebrospinal fluid (CSF) and plasma, and acetylcholinesterase activity of erythrocytes was determined. In addition, the molecular forms of acetylcholinesterase were measured in CSF. Severely demented patients had significantly lower acetylcholinesterase (p less than 0.01) and butyrylcholinesterase (p less than 0.05) activities in CSF than the controls had, but the activities of these enzymes in plasma and erythrocytes were within the same range in both groups. Acetylcholinesterase and butyrylcholinesterase activities in the CSF of mildly demented patients did not differ from control values. The ratio of the intermediate molecular form of acetylcholinesterase to the light molecular form of the enzyme did not differ significantly between patients with Alzheimer's disease and controls. According to our results, AChE levels were lower in the CSF of severely demented patients, but both light and intermediate molecular forms were affected.

Cholinergic deficit in Alzheimer's disease: a study based on CSF and autopsy data

Cholinesterase (ChE) activity was measured as a possible marker of cholinergic neurotransmission of the brain in CSF of 93 patients with probable Alzheimer's disease/senile dementia of the Alzheimer type (AD/SDAT) and of 29 control patients. ChE activity in CSF was decreased significantly in the AD/SDAT patients as compared to the controls. This reduction correlated significantly with the various measures of the severity of dementia. However, the reduction of ChE activity was only moderate (25-30%) even in patients with the most severe dementia and nonsignificant in patients with early symptoms of AD/SDAT. The significance of various confounding factors, which may interfere with CSF ChE measurements is discussed. Our findings seem to indicate that the deficiency of cholinergic neurons is not directly reflected in CSF and that the measurements of ChE activities in CSF are not helpful in diagnosing AD/SDAT. In the autopsy study the activities of cholineacetyltransferase (ChAT) and ChE were determined for ten brain areas of 20 AD/SDAT patients and of 14 controls. In AD/SDAT patients ChAT activity was profoundly decreased (50-85% decrease) in the cortical areas and hippocampus, but was unchanged or only mildly reduced in other subcortical brain areas. This study further confirms that the affection of cholinergic neurons is limited to projections from nucleus basalis to cortex and hippocampus, whereas other cholinergic neurons, like in striatum, seem to be relatively spared. In general, the activities of ChAT and ChE were lower in Alzheimer patients dying at younger age suggesting more severe disease process with these patients.

Effect of gamma-vinyl GABA treatment on cholinergic and aminergic neurotransmission and on cyclic nucleotides in human complex partial epilepsy--a CSF study

1. Gamma-vinyl GABA (GVG) is a new anticonvulsant drug that enhances levels of GABA in the brain by irreversibly inhibiting GABA transaminase. 2. To further evaluate the effects and mechanism of action of GVG in the human brain, we measured acetylcholinesterase (AChE) activity and levels of homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), cyclic nucleotides (cAMP, cGMP), total GABA (TGABA), and GVG in CSF of 78 patients with complex partial epilepsy. The CSF samples were taken at baseline and after 3 months of GVG administration (3 g GVG per day). Thereafter, the responders (= 50% decrease in number of seizures) were divided (double-blind) into two groups that received either 1.5 g or 3 g of GVG per day for the next 3 months. The third CSF sample was taken after this double-blind period. 3. TGABA levels were increased during the GVG treatment (p less than 0.001). In the whole group of patients AChE, HVA, 5-HIAA, and cAMP did not differ from baseline values, cGMP levels were slightly elevated after 3 months of GVG administration (p = 0.019), but were no longer elevated after 6 months. Responders had slightly lower AChE activity than nonresponders (p = 0.041). After 6 months of drug treatment the cGMP levels of patients receiving 1.5 g of GVG did not differ from those receiving 3 g. 4. In conclusion, GVG administration elevates levels of TGABA in the CSF without any clear of constant change to cholinergic and aminergic transmission or effect on cyclic nucleotides. Our study further emphasizes the specific mechanism of action of GVG via GABAergic transmission.

Monoamine metabolite concentrations and cholinesterase activities in cerebrospinal fluid of progressive dementia patients: relation to clinical parameters

Forty-five well clinically characterized patients with progressive dementia were investigated for lumbar cerebrospinal fluid (CSF) monoamine metabolites and cholinesterase activities. Monoamine concentrations were determined by reverse phase liquid chromatography with electrochemical detection and the cholinergic enzymes were measured photometrically. Firstly, all clinical and CSF parameters were studied in statistical cluster analyses to detect groups of variables which demonstrated a high correlation with respect to each other. The CSF transmitter markers were then used in multiple regression models to explain the variance of clinical variables as chosen from the cluster analyses. The degree of dementia, as assessed by global deterioration score (GDS) and activity in daily life (ADL) status, as well as the Alzheimer-related symptoms dyspraxia and dysphasia, were associated with low AChE activities in CSF. A presumed subgroup of dementia patients clinically characterized by asymmetry of neurological signs, increased unilateral tonus, stepwise progression, and high Hachinski score, showed low HVA concentrations in CSF. These data suggest a coupling of clinical/neurological parameters to different CSF transmitter profils and, thus, that CSF biochemical parameters are of use as antemortem markers in dementia conditions.

Increased monoamine metabolite concentrations and cholinesterase activities in cerebrospinal fluid of patients with acute stroke

Twenty-one patients with acute brain infarction, 8 with transient ischemic attack and 20 controls were investigated for lumbar cerebrospinal fluid (CSF) monoamine metabolites and cholinesterases. The diseased patients were lumbar punctured on 2 occasions, mean Days 1 (0-3) and 5 (3-9) after debut of symptoms. Monoamine concentrations were determined by reverse phase liquid chromatography with electrochemical detection and the cholinergic enzymes were measured photometrically. Increased concentrations of 3-methoxytyramine (3-MT), homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HI-AA) and increased activity of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in lumbar cerebrospinal fluid was found in patients with acute brain infarction when compared to control values, while the levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) were not altered. No change of any neurotransmitter metabolite concentration/enzyme activity were found between Day 1 and Day 5 in the diseased patients. These data suggest an increased release of these neurotransmitter markers from necrotic brain areas into the cerebrospinal fluid and/or altered barriers between blood, brain and CSF and/or a dysfunction of the arachnoid villi to clear substances from the CSF. We therefore concluded that CSF neurotransmitters may be useful as specific brain markers in acute stroke.

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.

Cerebrospinal fluid changes in experimental cardiac arrest (maximal stress)

Cardiac arrest produces a prompt and maximal increase of plasma catecholamines, with associated elevations of the hormones involved in the endocrine response to stress. To investigate the participation of the central nervous system (CNS) in the generation of the endocrine response, the catecholamines epinephrine and norepinephrine in cerebrospinal fluid (CSF) were measured before, during, and after cardiac arrest accompanied by cardiopulmonary resuscitation (CPR) in adrenalectomized (ADX) and sham-operated (SHAM) dogs. We also determined the activity of acetylcholine esterase (AChE), an intracellular enzyme released into the CSF after hypothalamic or caudate stimulation. During CPR, plasma epinephrine increased significantly in SHAM but not ADX dogs, increasing from (mean +/- SE) 480 +/- 171 to 29,800 +/- 14,200 pg/ml (P less than 0.05). Prearrest CSF norepinephrine was higher in ADX than SHAM dogs and increased in both groups with cardiac arrest, but the increase was significant only in SHAM animals; CSF epinephrine remained unchanged during or after cardiac arrest. CSF AChE activity increased during and after defibrillation; the difference with basal levels became significant when the peak postarrest values were considered (P less than 0.05). These results document biochemical changes occurring in the CNS during maximal stress represented by cardiac arrest. It is suggested that CSF norepinephrine and AChE activity elevations are markers for hypothalamic activation from the stress of cardiac arrest.

Release of acetylcholinesterase from the caudate nucleus of the rat

Acetylcholinesterase (AChE) can be released in the perfusate of rat caudate nucleus (CN) slices by two different modes of stimulation, with electrical stimulation at 5 Hz and with high concentrations of K+ (105 mM) using K+-propionate. We were unable to demonstrate AChE release with lower K+ concentrations (50 mM); however, at this concentration the drop in AChE activity seen in resting conditions was prevented. Practically all (95%) cholinesterase (ChE) found in the rat CN is AChE, which is represented by two major molecular forms (4S and 10S). In the perfusate, only AChE activity could be detected. A comparison of acetylcholine (ACh) and AChE release showed that maximal 3H-outflow and AChE release occurred at the same frequency (5 Hz), but the onset of AChE release was delayed. With high K+ (105 mM) depolarization, AChE release started after termination of the stimulation and continued for at least 50 min. These findings are consistent with the view that soluble form(s) of AChE can be slowly released from neurons under specific conditions of depolarization. In the caudate of the rat, the most likely sites for this release are processes of cholinergic interneurons. A hypothesis of AChE release is presented, and possible physiological and pathological implications of such a mechanism are discussed.

Antemortem markers of Alzheimer's disease

This review examines various approaches to the development of antemortem markers of Alzheimer's disease. Among the procedures discussed are: neurochemical and histopathologic studies of the cholinergic system, concentrating on CSF and blood plasma; genetic studies; imaging and electrophysiological studies; and neuroendocrine studies.

Molecular forms of cholinesterases in CSF of Alzheimer's disease/senile dementia of Alzheimer type patients and matched neurological controls

Acetylcholinesterase, pseudocholinesterase and their molecular forms were measured in the CSF of patients affected by Alzheimer's disease and of matched neurological controls. Three different molecular forms of ChE were found in the CSF of both groups of patients, but only two of them belonged to 'true' AChE. No differences were found between Alzheimer's disease patients and neurological controls in all the examined parameters.

Cholinesterases in cerebrospinal fluid. Correlations with clinical measures in Alzheimer's disease

Acetylcholinesterase and butyrylcholinesterase activities in cerebrospinal fluid were measured in 17 patients with Alzheimer's disease and 6 control patients, as potential clinical measures of impaired cholinergic neurotransmission in Alzheimer's disease. The activity of butyrylcholinesterase was decreased in patients with Alzheimer's disease compared to that observed in control patients, but there was overlap between values in the 2 groups. Low butyrylcholinesterase activity was correlated with severity of dementia, memory impairment, and language disorder. Acetylcholinesterase activity was significantly correlated with visual contrast sensitivity, but not with dementia severity, and did not differentiate patients with Alzheimer's disease from control cases. These results suggest that cholinesterases in cerebrospinal fluid are related to brain cholinesterases, and indicate that the activities of acetylcholinesterase and butyrylcholinesterase should be distinguished in studies of cerebrospinal fluid.

Cerebrospinal fluid acetylcholinesterase activity in senile dementia of the Alzheimer type

Acetylcholinesterase (AChE) activity was measured in cerebrospinal fluid (CSF) samples from 36 individuals, including 12 persons with Alzheimer's disease, 12 normal controls, and 12 patients with other dementias. AChE activity also was measured in 47 normal subjects whose ages ranged from 20 to 84 to evaluate the effect of age on AChE activity. CSF from patients with senile dementia of the Alzheimer type showed significantly lower mean AChE activity than in age-matched controls and patients with other dementia syndromes. No correlation was found between duration of illness, age, or severity of illness (as measured by the Mini-Mental State Examination score) and CSF AChE activity in Alzheimer's disease. AChE increased significantly over the age range of 20 to 84. CSF AChE activity may prove to be a useful diagnostic test to confirm the clinical diagnosis of moderate to severe Alzheimer's disease.

CSF acetylcholinesterase in dementia and in sequential samples of lumbar CSF

Acetylcholinesterase (AchE) activity (nmol/ml/min) was measured in lumbar CSF from 11 patients with dementia of the Alzheimer type (DAT), 8 patients with Korsakoff psychosis and 33 patients with low back pain who were undergoing myelography (controls). There was no significant difference in enzyme activity between the three groups. There was no significant correlation between age and AchE activity. AchE was also measured in 20 two-ml samples of CSF collected sequentially by lumbar puncture in two neurosurgical patients who had been recumbent for at least 8 hours. Variations in AchE between samples were small. In neither patient was there an increase in AchE activity with progressive sampling. These data indicate that (1) AchE is unchanged in Korsakoff psychosis (2) decreases in brain AchE which are found in DAT are not readily reflected in lumbar CSF (3) AchE in lumbar CSF has a diffuse origin including spinal cord (4) CSF AchE activity is unlikely to be a useful clinical marker for DAT.