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Acetylcholinesterase Activity (acetylcholinesterase + activity)
Selected AbstractsA novel approach to assessing percutaneous VX poisoning in the conscious guinea-pig,JOURNAL OF APPLIED TOXICOLOGY, Issue 5 2008Helen Mumford Abstract Nerve agents like VX (S-2-diisopropylaminoethyl-O-ethyl-methylphosphonothiolate) are potent irreversible acetylcholinesterase (AChE) inhibitors. Following percutaneous nerve agent exposure there is a slower rate of absorption, later onset and longer duration of signs of poisoning. Relatively little is known about the physiological effects of percutaneously applied nerve agent in unanaesthetised laboratory animals. Heart rate (ECG), brain electrical activity (EEG), body temperature, locomotor activity and clinical signs were monitored following percutaneous application of VX to conscious guinea-pigs. A fall in heart rate (bradycardia) preceded incapacitation following the highest VX dose, and occurred in the absence of incapacitation at the lower doses. Following the highest dose of VX (0.592 mg kg,1) three out of four animals died within 24 h. The lower two doses of VX (0.296 and 0.148 mg kg,1), produced extended periods of bradycardia in the absence of observable signs of poisoning. Bradycardia preceded, or occurred in the absence of, a temperature decrease; seizure-like EEG changes were not observed at any of the VX doses tested. Acetylcholinesterase activity was significantly inhibited in the blood and most brain areas at 48 h. There were significant dose-related decreases in body weight at 24 and 48 h following VX. This preliminary study suggests that decreased heart rate may be an early sign of the toxic effects of VX, whereas temperature and observable clinical signs are not good early indicators of percutaneous VX poisoning in this animal model. Future studies will use this model to assess the benefit of administering medical countermeasures in response to a defined decrease in heart rate. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. This article was published online on 5 December 2007. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected [30 May 2008]. [source] Potential Use of Biomarkers in Zooplankton as Early Warning Signals of Ecotoxicological Risk in the Marine Food ChainMARINE ECOLOGY, Issue 2002Roberta Minutoli Abstract. Zooplankton is an essential component of the marine and brackish food chains. The ecotoxicological risk of zooplanktonic communities, estimated by the modern methodological approach of biomarkers, can be used as an early warning signal of ecosystem health. The aim of this project is to estimate the potential use of several biomarkers (esterases, mixed function oxidases, porphyrins) in zooplanktonic organisms. Studies were carried out with different zooplanktonic crustaceans: the copepods Acartia margalefi and Acartia latisetosa collected in Ganzirri Lake (Messina); the mysid Siriella clausi collected in Faro Lake (Messina); the mysids Diamysis bahirensis, Siriella armata and Mysidopsis gibbosa collected in Stagnone di Marsala (Palermo); the Antarctic euphausiids Euphausia crystallorophias and Euphausia superba; the am-phipod Streetsia challengeri and the euphausiid Meganycthiphanes norvegica collected after a shore-stranding along Messina's Ionian coast. Moreover, experiments were carried out with the benthic decapods Eriphia verrucosa and Pachygrapsus marmoratus from a rocky shore of Messina's Ionian coast. Acetylcholinesterase activity (AChE) was determined in homogenates of whole organisms. The key result of this project concerns the different AChE activity basal values of different crustacean species. Particular attention should be paid to the difference in basal activity found between the Antarctic and the Mediterranean species. [source] Upper susceptibility threshold limits with confidence intervals: a method to identify normal and abnormal population values for laboratory toxicological parameters, based on acetylcholinesterase activities in sea licePEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 3 2006Anders Fallang Abstract The interpretation and importance of comparing field values of susceptibility to pesticides with a laboratory reference strain that might bear little resemblance to the actual situation in the field are problematic and a continuing subject of debate. In this paper a procedure for defining a ,normal sensitive' population from a field study of 383 individuals to provide a basis for analysing and interpreting in vitro results is described and examined. Instead of using only the 95th percentile, the upper and lower confidence limits for the 95th percentile were also compared to select the best estimation of the limit for the normal material. A field population constrained by the upper confidence limit for the 95th percentile provides appropriate descriptions of the normal material in this study. This approach should prove useful in studies of pesticide resistance in field populations. Copyright © 2006 Society of Chemical Industry [source] Effects of hunger level and nutrient balance on survival and acetylcholinesterase activity of dimethoate exposed wolf spidersENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2002Lars-Flemming Pedersen Abstract The influence of two nutritional factors (food quantity and quality) on the responses of a wolf spider, Pardosa prativaga (L.K.), to a high dose of the insecticide dimethoate, was investigated in a fully factorial experimental design. Spider groups with different (good and bad) nutrient balance were created by feeding them fruit flies of either high or low nutrient content for 28 days. Both groups were then split into satiated and 14 days starved subgroups. Each of these was further divided into insecticide treated and control halves. Survivorship and acetylcholinesterase (AChE) activity measured on the survivors were used as response variables. Survivorship after topical dimethoate exposure (LD50; 48 h) was influenced by spider body weight, nutrient balance, and starvation. Furthermore, AChE activity was significantly inhibited by dimethoate exposure. A significant interaction between nutrient balance, starvation, and dimethoate exposure revealed synergistic effects of starvation and nutrient imbalance on AChE inhibition by dimethoate in surviving spiders. These results show that the tolerance of non-target arthropods to dimethoate may vary depending on the nutritional history of the animal. [source] Effects of exposure to oxamyl, carbofuran, dichlorvos, and lindane on acetylcholinesterase activity in the gills of the Pacific oyster Crassostrea gigasENVIRONMENTAL TOXICOLOGY, Issue 4 2010Gerardo A. Anguiano Abstract Acetylcholinesterase (AChE) activity has been used to test the exposure of mollusk bivalves to pesticides and other pollutants. The Pacific oyster Crassostrea gigas is a species with a worldwide distribution, and it has a high commercial value. The use of this species as a bioindicator in the marine environment, and the use of measurements of AChE activity in tissues of C. gigas require prior evaluation of organisms exposed to several toxic compounds in the laboratory. In our study, the effects of pesticides on AChE activity in the gills and mantle tissues of C. gigas were analyzed by exposing animals to organophosphate (dichlorvos), carbamate (carbofuran and oxamyl), and organochlorine (lindane) pesticides. Adult Pacific oysters were exposed to several concentrations (0.1,200 ,M) of dichlorvos, carbofuran, and oxamyl for 96 h, and lindane (1.0 and 2.5 ,M) was applied for 12 days. In gill tissues, all pesticides analyzed caused a decrease in AChE activity when compared to the control unexposed group. The mean inhibition concentration (IC50) values were determined for dichlorvos, carbofuran, and oxamyl pesticides. Dichlorvos had the highest toxic effect, with an IC50 of 1.08 ,M; lesser effects were caused by oxamyl and carbofuran, with IC50s of 1.67 and 3.03 ,M, respectively. This study reports the effects of pesticides with several chemical structures and validates measurement of AChE activity in the gill tissues of C. gigas for use in environmental evaluations or food quality tests. © 2009 Wiley Periodicals, Inc. Environ Toxicol 25: 327,332, 2010. [source] Field evaluation of an avian risk assessment modelENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2006Nimish B. Vyas Abstract We conducted two laboratory subacute dietary toxicity tests and one outdoor subacute dietary toxicity test to determine the effectiveness of the U.S. Environmental Protection Agency's deterministic risk assessment model for evaluating the potential of adverse effects to birds in the field. We tested technical-grade diazinon and its D·Z·N® 50W (50% diazinon active ingredient wettable powder) formulation on Canada goose (Branta canadensis) goslings. Brain acetylcholinesterase activity was measured, and the feathers and skin, feet, and gastrointestinal contents were analyzed for diazinon residues. The dose,response curves showed that diazinon was significantly more toxic to goslings in the outdoor test than in the laboratory tests. The deterministic risk assessment method identified the potential for risk to birds in general, but the factors associated with extrapolating from the laboratory to the field, and from the laboratory test species to other species, resulted in the underestimation of risk to the goslings. The present study indicates that laboratory-based risk quotients should be interpreted with caution. [source] Intraclonal variability in Daphnia acetylcholinesterase activity: The implications for its applicability as a biomarkerENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2003Liane Biehl Printes Abstract The relationship between individual growth and acetylcholinesterase (AChE) activity was evaluated for Daphnia magna. Analysis on the influence of two different culture media on baseline AChE activity was performed with Daphnia similis. The results indicated an inverse relationship between D. magna body length and AChE activity. An increase in total protein, which was not proportional to an increase in the rate of the substrate hydrolysis (, absorbance/min), seems to be the reason for this inverse size versus AChE activity relationship. Therefore, toxicants such as phenobarbital, which affect protein and size but not AChE activity directly, have an overall affect on AChE activity. In contrast, the AChE inhibitor parathion altered AChE activity but not protein. Culture medium also had a significant affect on AChE activity in D. similis. Changes in total protein seem to be the main reason for the variations in baseline AChE activity in Daphnia observed in the different evaluations performed in this work. Therefore, AChE activity in Daphnia must be interpreted carefully, and variations related to changes in total protein must be taken into account when applying this enzyme as a biomarker in biological monitoring. [source] Effects of Anabaena spiroides (cyanobacteria) aqueous extracts on the acetylcholinesterase activity of aquatic speciesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2001José María Monserrat Abstract The effects of aqueous extracts from a cyanobacteria species, Anabaena spiroides, on fish (Odontesthes argentinensis), crab (Callinectes sapidus), and purified eel acetylcholinesterase (AChE) activity were studied. In vitro concentrations of A. spiroides aqueous extract that inhibited 50% of enzyme activity (IC50) were 23.0, 17.2, and 45.0 mg/L of lyophilized cyanobacteria for eel, fish, and crab AChE, respectively. Eel AChE inhibition follows pseudo-first-order kinetics, the same expected for organophosphorus pesticides. Inhibition of purified eel AChE using mixtures of bioxidized malathion and aqueous extract of A. spiroides showed a competitive feature (p < 0.05), suggesting that the toxin(s) could be structurally similar to an organophosphorus pesticide and that toxins present in the aqueous extract inhibit the active site of the enzyme. The inhibition recovery assays using 2-PAM (0.3 mM) showed that (1) bioxidized malathion inhibited 27.0 ± 1.1% of crab and 36.5 ± 0.1% of eel AChE activities; (2) with bioxidized malathion + 2-PAM the registered inhibition was 13.2 ± 2.1% and 3.7 ± 0.5% in crab and eel AChE, respectively; (3) the aqueous extract from A. spiroides inhibited 17.4 ± 2.2% and 59.9 ± 0.5% of crab and eel AChE activity, respectively; and (4) aqueous extract + 2-PAM inhibited 22.3 ± 2.6 and 61.5 ± 0.2% of crab and eel AChEs. The absence of enzyme activity recovery after 2-PAM exposure could imply that the enzyme aging process was extremely quick. [source] Transection of the sciatic nerve and reinnervation in adult rats: muscle and endplate morphologyEQUINE VETERINARY JOURNAL, Issue S33 2001J. IJKEMA-PAASSEN Summary The functional recovery after peripheral nerve lesions is generally poor. We studied whether changes in muscles after reinnervation might explain such disappointing results. The functional recovery after peripheral nerve lesions is generally poor. Changes in muscle morphology and neuromuscular innervation might partly explain this lack of compensation. In order to test this hypothesis, we studied muscular differentiation in the soleus, gastrocnemius and tibialis anterior muscles at 7, 15 and 21 weeks after a sciatic nerve lesion in adult rats. In the gastrocnemius and tibialis muscles the percentages of type II muscles fibres were decreased at 7 and 15 weeks but at 21 weeks they again approached normal values. The soleus muscle, however, was permanently decreased in size and this muscle, in contrast to the normal soleus muscle, contained mainly type II fibres. The morphology of the endplates showed distinct stages of degeneration and reinnervation. Two weeks after denervation, in rats in which reinnervation was prevented, all 3 muscles contained considerable numbers of morphologically abnormal endplates and, after 7 weeks, no endplates were detected. During reinnervation, endplates showing signs of acetylcholinesterase activity were observed in all 3 muscles from 7 weeks. At later ages a shift towards morphologically normal endplates occurred, but complete recovery was not observed. Endplates in all 3 muscles were polyneurally innervated at 7 weeks. Although these percentages decreased over age, polyneural innervation was still present at 21 weeks. We conclude that the changes in the distribution of fibre types, abnormal endplate morphology and polyneural innervation may in part explain the poor functional recovery after peripheral nerve lesions. [source] Inhibition of acetylcholinesterase activity by tea tree oil and constituent terpenoidsFLAVOUR AND FRAGRANCE JOURNAL, Issue 2 2006Mitsuo Miyazawa Abstract In vitro inhibition of bovine erythrocyte acetylcholinesterase (AChE) activity by tea tree oil was investigated. The main constituents in the tea tree oil batch used for the analysis of AChE inhibition were terpinen-4-ol (35.6%), , -terpinene (19.5%), , -terpinene (8.3%), p -cymene (7.2%) and 1,8-cineole (4.4%). AChE was measured by a colorimetric method. IC50 values were obtained for tea tree oil and , -pinene and were 51.2 µg/ml and 57.1 µg/ml, respectively. Tea tree oil was found to contain mixed-type inhibitors; a mixture of main constituents and main constituents showed competitive inhibition. Copyright © 2005 John Wiley & Sons, Ltd. [source] Inhibition of acetylcholinesterase activity by tea tree oil and constituent terpenoidsFLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2005Mitsuo Miyazawa Abstract In vitro inhibition of bovine erythrocyte acetylcholinesterase activity by tea tree oil was investigated. The main constituents in the tea tree oil batch used for analysis of acetylcholinesterase inhibition were terpinen-4-ol (35.6%), , -terpinene (19.5%), , -terpinene (8.3%), p -cymene (7.2%) and 1,8-cineole (4.4%). AChE was measured by a colorimetric method. IC50 values were obtained for tea tree oil and , -pinene and were 51.2 and 57.1 µg[sol ]ml, respectively. Tea tree oil was found to comprise of mixed type inhibitors as the main constituents. The main constituents were competitive inhibitors. Copyright © 2005 John Wiley & Sons, Ltd. [source] ORIGINAL ARTICLE: Brain and hypophyseal acetylcholinesterase activity of pubertal boars fed dietary fumonisin B1JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2010F. A. Gbore Summary The effects of dietary fumonisin B1 (FB1) on regional brain and hypophyseal activities of AChE (EC 3117), the enzyme which catalyses the hydrolysis of acetylcholine, were studied using 24 male Large White weanling pigs divided into four groups. Each group received one of the four diets containing 0.2, 5.0, 10.0 and 15.0 mg FB1/kg in a 6-month feeding trial. All animals were slaughtered at the end of the feeding trial; the brains and the hypophyses obtained were carefully dissected out. Significant (p < 0.05) influence of dietary FB1 on regional brain and hypophyseal AChE activities were observed. The AChE activities in the pons, amygdala, hypothalamus and the medulla oblongata declined significantly (p < 0.05) with increased dietary FB1 concentrations. The findings of this study suggest that diets containing 5.0 mg FB1/kg and above significantly (p < 0.05) altered regional brain and hypophyseal AChE activities in the animals. Dietary exposure to FB1 at a concentration of approximately 5.0 mg/kg or more for a 6-month period is a potential health risk that may induce adverse physiological response resulting from altered brain neurochemistry in growing pigs. [source] Inhibition of acetylcholinesterase by physostigmine analogs: Conformational mobility of cysteine loop due to the steric effect of the alkyl chainJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 2 2002Enrico Gavuzzo Abstract The effect of a series of physostigmine analogs on acetylcholinesterase activity was investigated. The second-order rate constant kon of the enzyme,inhibitor complex correlates with the conformational positioning of aromatic residues, especially Trp84, in the transition state complex. The van der Waals interactions are an important structural element of this conformational change. A transient mobility of the cysteine loop (Cys67,Cys94) was confined only to the presence of a significant steric effect. Even with this limitation, however, the steric effect seems to be an appropriate model for future tests on the "back door" hypothesis involving facilitated opening for faster product clearance. © 2002 Wiley Periodicals, Inc. J Biochem Mol Toxicol 16:64,69, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/jbt.10026 [source] Cholinergic Mediation of Alcohol-Induced Experimental PancreatitisALCOHOLISM, Issue 10 2010Aurelia Lugea Objectives:, The mechanisms initiating pancreatitis in patients with chronic alcohol abuse are poorly understood. Although alcohol feeding has been previously suggested to alter cholinergic pathways, the effects of these cholinergic alterations in promoting pancreatitis have not been characterized. For this study, we determined the role of the cholinergic system in ethanol-induced sensitizing effects on cerulein pancreatitis. Methods:, Rats were pair-fed control and ethanol-containing Lieber-DeCarli diets for 6 weeks followed by parenteral administration of 4 hourly intraperitoneal injections of the cholecystokinin analog, cerulein at 0.5 ,g/kg. This dose of cerulein was selected because it caused pancreatic injury in ethanol-fed but not in control-fed rats. Pancreatitis was preceded by treatment with the muscarinic receptor antagonist atropine or by bilateral subdiaphragmatic vagotomy. Measurement of pancreatic pathology included serum lipase activity, pancreatic trypsin, and caspase-3 activities, and markers of pancreatic necrosis, apoptosis, and autophagy. In addition, we measured the effects of ethanol feeding on pancreatic acetylcholinesterase activity and pancreatic levels of the muscarinic acetylcholine receptors m1 and m3. Finally, we examined the synergistic effects of ethanol and carbachol on inducing acinar cell damage. Results:, We found that atropine blocked almost completely pancreatic pathology caused by cerulein administration in ethanol-fed rats, while vagotomy was less effective. Ethanol feeding did not alter expression levels of cholinergic muscarinic receptors in the pancreas but significantly decreased pancreatic acetylcholinesterase activity, suggesting that acetylcholine levels and cholinergic input within the pancreas can be higher in ethanol-fed rats. We further found that ethanol treatment of pancreatic acinar cells augmented pancreatic injury responses caused by the cholinergic agonist, carbachol. Conclusion:, These results demonstrate key roles for the cholinergic system in the mechanisms of alcoholic pancreatitis. [source] Effect of chronic treatment of carvedilol on oxidative stress in an intracerebroventricular streptozotocin induced model of dementia in ratsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 12 2009Atish Kumar Prakash Abstract Objectives Oxidative stress is emerging as an important issue in the pathogenesis of dementia. This study was conducted to investigate the possible neuroprotective effects of carvedilol against streptozotocin induced behavioural alterations and oxidative damage in rats. Methods An intracerbroventricular cannula was implanted in the lateral ventricles of male Wistar rats. Various behavioural (locomotor activity, Morris water maze task) and biochemical parameters (lipid peroxidation, nitrate concentration, catalase, acetylcholinesterase, reduced glutathione and protein) were assessed. Key findings Intracerebroventricular administration of streptozotocin caused a significant memory deficit as evaluated in the Morris water maze task paradigms, and caused marked oxidative damage as indicated by significant increases in malondialdehyde and nitrite levels, and depletion of superoxide dismutase, catalase and reduced glutathione levels. It also caused a significant increase in acetylcholinesterase activity. Chronic administration of carvedilol (1 and 2 mg/kg, i.p.) for a period of 25 days starting 4 days before streptozotocin administration resulted in an improvement in memory retention, and attenuation of oxidative damage and acetylcholinesterase activity. Conclusions This study demonstrates the effectiveness of carvedilol in preventing cognitive deficits as well as the oxidative stress caused by intracerbroventicular administration of streptozotocin in rats. Carvedilol may have potential in the treatment of neurodegenerative diseases. [source] Acotiamide (Z-338) as a possible candidate for the treatment of functional dyspepsiaNEUROGASTROENTEROLOGY & MOTILITY, Issue 6 2010H. Suzuki Abstract Acotiamide hydrochloride is a novel upper gastrointestinal (GI) motility modulator and stress regulator currently being developed for the treatment of functional dyspepsia (FD). The mechanism underlying the enhancement of GI motility by this agent has been proposed to be based on its muscarinic antagonism and inhibitory effects on acetylcholinesterase activity. Pathophysiological studies showed that acotiamide significantly improved both delayed gastric emptying and feeding inhibition in restraint stress-induced model, but did not affect both normal gastric emptying and feeding in intact animals, indicating that acotiamide exerted effects only on the impaired gastric emptying and feeding behavior. According to the clinical pilot study in Europe, acotiamide, at the dose of 100 mg t.i.d., showed to improve the symptoms and quality of life of patients with FD, indicating the need for larger scale symptomatic studies on the efficacy of acotiamide in patients with FD. The recent phase II studies conducted in Japan presented in this issue of the journal also confirmed that acotiamide, at the optimal dose of 100 mg, has potential therapeutic efficacy, especially for meal-related FD symptoms. Although a phase III study is on going, acotiamide is now expected as a novel treatment option for FD. [source] Protective effect of quercetin against ICV colchicine-induced cognitive dysfunctions and oxidative damage in ratsPHYTOTHERAPY RESEARCH, Issue 12 2008Anil Kumar Abstract Intracerebroventricular (i.c.v.) administration of colchicine, a microtubule-disrupting agent, causes cognitive dysfunction and oxidative stress. The present study was designed to investigate the protective effects of quercetin against colchicine-induced memory impairment and oxidative damage in rats. An i.c.v. cannula was implanted in the lateral ventricle of male Wistar rats. Colchicine was administered at dose of 15 µg/rat. Morris water maze and plus-maze performance tests were used to assess memory tasks. Various biochemical parameters such as lipid peroxidation, reduced glutathione, nitrite level, acetylcholinesterase and proteins were also assessed. Central administration of colchicine (15 µg/rat) showed poor retention of memory. Chronic treatment with quercetin (20 and 40 mg/kg, p.o.) twice daily for a period of 25 days beginning 4 days prior to colchicine injection significantly improved the colchicine-induced cognitive impairment. Biochemical analysis revealed that i.c.v. colchicine injection significantly increased lipid peroxidation, nitrite and depleted reduced glutathione activity in the brains of rats. Chronic administration of quercetin significantly attenuated elevated lipid peroxidation and restored the depleted reduced glutathione, acetylcholinesterase activity and nitrite activity. The results of the present study clearly indicated that quercetin has a neuroprotective effect against colchicine-induced cognitive dysfunctions and oxidative damage. This article was published online on 3 November 2008. An error was subsequently identified. This notice is included in the online and print version to indicate that both have been corrected. [24 November 2008] Copyright © 2008 John Wiley & Sons, Ltd. [source] Effect of N -Acetyl Cysteine against Aluminium-induced Cognitive Dysfunction and Oxidative Damage in RatsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2 2009Atish Prakash Chronic aluminium exposure induces oxidative stress and increases amyloid beta levels in vivo. The role of oxidative stress has been well-suggested in these cognitive problems. Therefore, the present study was designed to explore the possible role of N -acetyl cysteine against aluminium mediating cognitive dysfunction and oxidative stress in rats. Aluminium chloride (100 mg/kg, p.o.) was given to rats daily for 6 weeks. N -acetyl cysteine (per se; 50 and 100 mg/kg, i.p.) pre-treatment was given 30 min. before aluminium daily for 6 weeks. On the third (21st day) and sixth week (42nd day) of the study, various behavioural tests (Morris water maze and elevated plus maze task paradigms) and locomotion (photoactometer) were done to evaluate cognitive tasks. The rats were killed on the 43rd day following the last behavioural test, and various biochemical tests were performed to assess the extent of oxidative damage. Chronic aluminium chloride administration resulted in poor retention of memory in Morris water maze, elevated plus maze task paradigms and caused marked oxidative damage. It also caused a significant increase in the acetylcholinesterase activity. Chronic administration of N -acetyl cysteine significantly improved memory retention in tasks, attenuated oxidative damage and acetylcholinesterase activity in aluminium-treated rats. The study suggests a neuroprotective effect of N -acetyl cysteine against aluminium-induced cognitive dysfunction and oxidative damage. [source] Four Weeks' Inhalation Exposure of Long Evans Rats to 4- tert -Butyltoluene: Effect on Evoked Potentials, Behaviour, and Brain NeurochemistryBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 1 2000Henrik Rye Lam Long-lasting central nervous system (CNS) neurotoxicity of 4- tert -butyltoluene (TBT) has been investigated using electrophysiology, behaviour, and neurochemistry in Long Evans rats exposed by inhalation to 0, 20, or 40 p.p.m. TBT 6 hr/day, 7 days/week for 4 weeks. Flash evoked potentials and somatosensory evoked potentials were not affected by TBT. In Auditory Brain Stem Response there was no shift in hearing threshold, but the amplitude of the first wave was increased in both exposed groups at high stimulus levels. Three to four months after the end of exposure, behavioural studies in Morris water maze and eight-arm maze failed to demonstrate any TBT induced effects. Exposure was followed by a 5 months exposure-free period prior to gross regional and subcellular (synaptosomal) neurochemical investigations of the brain. TBT reduced the NA concentration in whole brain minus cerebellum. Synaptosomal choline acetyltransferase activity increased and acetylcholinesterase activity was unchanged suggesting increased synaptosomal ability for acetylcholine synthesis. The relative and total yield of synaptosomal protein was reduced suggesting reduced density and total number of synapses in situ, respectively. We hypothesise that a reduced yield of synaptosomal protein reflects a more general effect of organic solvent exposure on the software of the brain. The synaptosomal concentration per mg synaptosomal protein and the total amount of 5-hydroxytryptamine were not affected whereas the total amount of synaptosomal noradrenaline decreased. The concentration and the total amount of synaptosomal dopamine decreased. The noradrenergic and dopaminergic parts of CNS may be more vulnerable to TBT than the serotonergic, and these long-lasting effects may cause or reflect TBT-compromised CNS function. [source] Sinusoidal ELF magnetic fields affect acetylcholinesterase activity in cerebellum synaptosomal membranesBIOELECTROMAGNETICS, Issue 4 2010Silvia Ravera Abstract The effects of extremely low frequency magnetic fields (ELF-MF) on acetylcholinesterase (AChE) activity of synaptosomal membranes were investigated. Sinusoidal fields with 50,Hz frequency and different amplitudes caused AChE activity to decrease about 27% with a threshold of about 0.74,mT. The decrease in enzymatic activity was independent of the time of permanence in the field and was completely reversible. Identical results were obtained with exposure to static MF of the same amplitudes. Moreover, the inhibitory effects on enzymatic activity are spread over frequency windows with different maximal values at 60, 200, 350, and 475,Hz. When synaptosomal membranes were solubilized with Triton, ELF-MF did not affect AChE activity, suggesting the crucial role of the membrane, as well as the lipid linkage of the enzyme, in determining the conditions for inactivation. The results are discussed in order to give an interpretation at molecular level of the macroscopic effects produced by ELF-MF on biological systems, in particular the alterations of embryo development in many organisms due to acetylcholine accumulation. Bioelectromagnetics 31:270,276, 2010. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||