A comparison of tabun-inhibited rat brain acetylcholinesterase reactivation by three oximes (HI-6, obidoxime, and K048) in vivo detected by biochemical and histochemical techniques

Tabun belongs to the most toxic nerve agents. Its mechanism of action is based on acetylcholinesterase (AChE) inhibition at the peripheral and central nervous systems. Therapeutic countermeasures comprise administration of atropine with cholinesterase reactivators able to reactivate the inhibited enzyme. Reactivation of AChE is determined mostly biochemically without specification of different brain structures. Histochemical determination allows a fine search for different structures but is performed mostly without quantitative evaluation. In rats intoxicated with tabun and treated with a combination of atropine and HI-6, obidoxime, or new oxime K048, AChE activities in different brain structures were determined using biochemical and quantitative histochemical methods. Inhibition of AChE following untreated tabun intoxication was different in the various brain structures, having the highest degree in the frontal cortex and reticular formation and lowest in the basal ganglia and substantia nigra. Treatment resulted in an increase of AChE activity detected by both methods. The highest increase was observed in the frontal cortex. This reactivation was increased in the order HI-6 < K048 < obidoxime; however, this order was not uniform for all brain parts studied. A correlation between AChE activity detected by histochemical and biochemical methods was demonstrated. The results suggest that for the mechanism of action of the nerve agent tabun, reactivation in various parts of the brain is not of the same physiological importance. AChE activity in the pontomedullar area and frontal cortex seems to be the most important for the therapeutic effect of the reactivators. HI-6 was not a good reactivator for the treatment of tabun intoxication.     

A comparison of tabun-inhibited rat brain acetylcholinesterase reactivation by three oximes (HI-6, obidoxime,and K048) in vivo detected by biochemical and histochemical techniques

Tabun belongs to the most toxic nerve agents. Its mechanism of action is based on acetylcholinesterase (AChE) inhibition at the peripheral and central nervous systems. Therapeutic countermeasures comprise administration of atropine with cholinesterase reactivators able to reactivate the inhibited enzyme. Reactivation of AChE is determined mostly biochemically without specification of different brain structures. Histochemical determination allows a fine search for different structures but is performed mostly without quantitative evaluation. In rats intoxicated with tabun and treated with a combination of atropine and HI-6, obidoxime, or new oxime K048, AChE activities in different brain structures were determined using biochemical and quantitative histochemical methods. Inhibition of AChE following untreated tabun intoxication was different in the various brain structures, having the highest degree in the frontal cortex and reticular formation and lowest in the basal ganglia and substantia nigra. Treatment resulted in an increase of AChE activity detected by both methods. The highest increase was observed in the frontal cortex. This reactivation was increased in the order HI-6 < K048 < obidoxime; however, this order was not uniform for all brain parts studied. A correlation between AChE activity detected by histochemical and biochemical methods was demonstrated. The results suggest that for the mechanism of action of the nerve agent tabun, reactivation in various parts of the brain is not of the same physiological importance. AChE activity in the pontomedullar area and frontal cortex seems to be the most important for the therapeutic effect of the reactivators. HI-6 was not a good reactivator for the treatment of tabun intoxication.     

An attempt to assess functionally minimal acetylcholinesterase activity necessary for survival of rats intoxicated with nerve agents

Acetylcholinesterase (AChE, EC 3.1.1.7) is an important enzyme for cholinergic nerve transmission. The action of toxic organophosphates such as nerve agents is based on AChE inhibition. The death following acute nerve agent poisoning is due to central or peripheral respiratory/cardiac failure. Therefore, the changes in AChE activity following nerve agents acting predominantly on the central (sarin, soman) or peripheral (VX) level were studied. It is known that AChE activity in different structures exists in relative excess. Female Wistar rats intoxicated with sarin, soman, and VX in different doses (0.5-2.0xLD(50)) were divided into groups of survived and died animals. AChE activities in diaphragm, brain parts (pontomedullar area, frontal cortex, basal ganglia, in some cases other parts of the brain) were determined and the rest of activity (in %) was correlated with survival/death of animals. More precise elucidation of action of nerve agents and the assessment of minimal AChE activity in different organs compatible with the survival of organism poisoned with nerve agents were the aims of this study.     

Comparison of changes in AChE activity in the brain of the laboratory rat after soman and tabun intoxication

The aim of this study was to compare changes in activity of acetylcholinesterase (AChE) in the brain and motor endplates of rat after administration of soman and tabun. We took brain and diaphragm from laboratory rats administered a median lethal dose (LD(50)) of soman or tabun. Enzyme activity of AChE was studied in selected structures of brain and in motor endplates in the diaphragm. Histochemical detection of AChE by Karnovski and Roots with simultaneous histochemical detection of alkaline phosphatase in case of brain sections was used. The highest activity of AChE in the control group was found in the striatum, amygdaloid nuclei, substantia nigra, superior colliculi, and motor nuclei of cranial nerves V, X a XII. LD(50) of both nerve agents dramatically decreased the activity of AChE in the structures studied--both brain and diaphragm. After intoxication by either agent, activity in above mentioned nuclei was characterized as low or focally moderate. Very low activity was seen in some structures (CA3 field of hippocampus, some nuclei of the tegmentum and cerebellar cortex). We found minimal differences in the histochemical picture of soman or tabun intoxication, apart from the striatum and the superior colliculi which showed stronger inhibition by tabun.     

Pharmacology of HI-6, an H-series oxime

HI-6 is an oxime experimentally developed for reactivation of previously untreatable soman-phosphorylated acetylcholinesterase. It has been shown to be effective in restoring acetylcholinesterase activity after poisoning with other "nerve agents" namely VX and sarin; however, its antidotal qualities for the treatment of organophosphorus pesticide poisoning are not well known. HI-6, and other H-series oximes, apparently act in a number of ways: reactivation of acetylcholinesterase, blockage of ganglia and muscarinic receptors, stimulation of vasopressor and respiratory centre receptors, chemical combination with agents, restoration of neuromuscular transmission, retardation of the formation of the aged inhibitor-enzyme complex, and (or) inhibition of the release of acetylcholine.     

Structures of paraoxon‐inhibited human acetylcholinesterase reveal perturbations of the acyl loop and the dimer interface

Irreversible inhibition of the essential nervous system enzyme acetylcholinesterase by organophosphate nerve agents and pesticides may quickly lead to death. Oxime reactivators currently used as antidotes are generally less effective against pesticide exposure than nerve agent exposure, and pesticide exposure constitutes the majority of cases of organophosphate poisoning in the world. The current lack of published structural data specific to human acetylcholinesterase organophosphate‐inhibited and oxime‐bound states hinders development of effective medical treatments. We have solved structures of human acetylcholinesterase in different states in complex with the organophosphate insecticide, paraoxon, and oximes. Reaction with paraoxon results in a highly perturbed acyl loop that causes a narrowing of the gorge in the peripheral site that may impede entry of reactivators. This appears characteristic of acetylcholinesterase inhibition by organophosphate insecticides but not nerve agents. Additional changes seen at the dimer interface are novel and provide further examples of the disruptive effect of paraoxon. Ternary structures of paraoxon‐inhibited human acetylcholinesterase in complex with the oximes HI6 and 2‐PAM reveals relatively poor positioning for reactivation. This study provides a structural foundation for improved reactivator design for the treatment of organophosphate intoxication. Proteins 2016; 84:1246–1256. © 2016 Wiley Periodicals, Inc.     

Monoclonal Antibody Tor 23 Recognizes a Determinant of a Presynaptic Acetylcholinesterase

A significant proportion of the acetylcholinesterase that is present in the electric organ of Torpedo californica exists as a presynaptic membrane molecule. The monoclonal antibody Tor 23 binds the Torpedo presynaptic nerve membrane where it recognizes a polypeptide of 68,000 daltons. Our present studies indicate that Tor 23 identifies acetylcholinesterase. From the homogenates of Torpedo nerve terminals, Tor 23 immunoprecipitates measurable esterase activity. Esterase precipitation was not observed with no Tor 23 added; nor was it observed with any other test antibodies, including other Tor antibodies, in particular, Tor 70, which binds, as does Tor 23, to the presynaptic nerve membrane. The esterase activity was specific for acetylcholinesterase. Our studies indicate the molecule defined by Tor 23 has the solubility properties described for that of presynaptic acetylcholinesterase: it is soluble in detergent-treated electroplax homogenates and insoluble in high-salt extractions. In sections of Torpedo back muscle, both nerve and endplate acetylcholinesterase can be detected histochemically. Tor 23 localizes to the nerve and is not clustered at the endplate. The utility of the antibody Tor 23 thus includes biochemical and histological analyses of the multiple forms of acetylcholinesterase.     

In vivo antioxidative and neuroprotective effect of 4-Allyl-2-methoxyphenol against chlorpyrifos-induced neurotoxicity in rat brain

Chlorpyrifos exposure leads to various neurological disorders adverting disturbance in molecular pathways and normal brain functions. Major complications arise when these potent nerve agents access neuronal mechanisms causing adverse effect on acetylcholinesterase and brain lipids with generation of reactive oxygen species. Chlorpyrifos elicits chronic intoxication leading to redox disturbance with irreversible brain damage and oxidative stress. In the present study, neuroprotective and anti-apoptotic effects of eugenol (EO), a phenolic antioxidant, against chlorpyrifos-induced neurotoxicity was explored on rat brain cortex. Rats treated orally with chlorpyrifos [89.4 mg/kg body weight (BW)] for 15 consecutive days showed changes in brain lipid profile, increased levels of lipid peroxidation, inhibition of acetylcholinesterase activity, and changes in antioxidant enzymes. EO (250 mg/kg BW), administered 1 h after chlorpyrifos treatment, restored lipid, acetylcholinesterase, and antioxidant enzyme levels of brain cortex by suppressing chlorpyrifos-induced oxidative stress and neurotoxicity. Histological findings further demonstrated damage to brain morphology with increased protein levels of caspase-3 in CPF-treated animals. Alterations caused by neurotoxic effects of chlorpyrifos were attenuated by EO administration with decreased protein expressions of caspase-3. Thus, through its antioxidant and anti-apoptotic activities, EO showed protective effect against chlorpyrifos-induced neuronal damage.     

Inactivation of rat brain acetylcholinesterase by pyridoxal 5'-phosphate

Effects of pyridoxal 5'-phosphate on the activity of crude and purified acetylcholinesterase from cerebral hemispheres of adult rat brain were examined. Acetylcholinesterase was completely inactivated by incubation with 0.5 mM pyridoxal 5'-phosphate. The enzyme activity remained unaltered in the presence of analogs of pyridoxal 5'-phosphate, pyridoxal, pyridoxamine and pyridoxamine 5'-phosphate. The inhibition of acetylcholinesterase activity by pyridoxal 5'-phosphate appeared to be of a noncompetitive nature, as determined by Lineweaver-Burk analysis. The inhibitory effect of pyridoxal 5'-phosphate on acetylcholinesterase appeared to be a general one, as the activity of the enzyme from the brains of immature chick and egg-laying hen, and from different tissues of the adult male rats, exhibited a similar pattern in the presence of the inhibitor. The inhibitory effects of pyridoxal 5'-phosphate could be reversed upon exhaustive dialysis of the pyridoxal 5'-phosphate-treated acetylcholinesterase preparations. We propose that the effects of pyridoxal 5'-phosphate are due to its interaction with acetylcholinesterase, and that it can be employed as a useful tool for studying biochemical aspects of this important brain enzyme.     

Isolation and characterization of axolemma-enriched fractions from rabbit and bovine peripheral nerve

Axolemma-enriched fractions were isolated from bovine spinal accessory nerves, bovine intradural dorsal roots, and rabbit sciatic nerve by differential centrifugation and separation on a linear 10–40% sucrose (w/w) gradient. The fractions were enriched 4 to 10 fold in acetylcholinesterase, a biochemical marker for axolemma. Axolemma-enriched fractions isolated from uniformly well-myelinated fibers (bovine spinal accessory nerve) contained lower CNPase activity and higher acetylcholinesterase activity than comparable fractions isolated from variably myelinated fibers (rabbit sciatic nerve and bovine intradural roots). Separation by polyacrylamide electrophoresis showed that the molecular weight distribution of all peripheral nerve axolemma-enriched fractions was similar and ranged from 20 to over 150 kilodaltons. All axolemma-enriched fractions appeared to contain a small but variable amount of myelin-specific proteins. Based on biochemical properties, peripheral nerves containing uniformly well-myelinated fibers yield an axolemma-enriched fraction which is least contaminated with myelin-related membranes.     

ORIGINAL ARTICLE: Evaluation of miosis,behavior and cholinesterase inhibition from low‐level,whole‐body vapor exposure to soman in African green monkeys (Chlorocebus sabeus)*

Background Relatively little is known about the effects of very low‐level exposures to nerve agents where few signs or symptoms are present. Methods African green monkeys (Chlorocebus sabeus) (n = 8) were exposed for 10 min, whole‐body, to a single concentration of soman (0.028–0.891 mg/m³). Results EC₅₀ values for miosis were determined to be 0.055 mg/m³ and 0.132 mg/m³ when defined as a 50 percent reduction in pupil area and diameter, respectively. In general, performance on a serial probe recognition task remained unchanged at lower concentrations, but responding was suppressed at the largest concentration tested. Soman produced concentration‐dependent inhibition of acetylcholinesterase activity and, to a lesser extent, butyrylcholinesterase activity. Conclusions These results characterize threshold soman exposure concentrations that produce miosis in the absence of other overt signs of toxicity and extend previous studies indicating that miosis is a valuable early indicator for the detection of soman vapor exposure.     

Inactivation of rat brain acetylcholinesterase by pyridoxal 5′-phosphate

Effects of pyridoxal 5′-phosphate on the activity of crude and purified acetylcholinesterase from cerebral hemispheres of adult rat brain were examined. Acetylcholinesterase was completely inactivated by incubation with 0.5 mM pyridoxal 5′-phosphate. The enzyme activity remained unaltered in the presence of analogs of pyridoxal 5′-phosphate, pyridoxal, pyridoxamine and pyridoxamine 5′-phosphate. The inhibition of acetylcholinesterase activity by pyridoxal 5′-phosphate appeared to be of a noncompetitive nature, as determined by Lineweaver-Burk analysis. The inhibitory effect of pyridoxal 5′-phosphate on acetylcholinesterase appeared to be a general one, as the activity of the enzyme from the brains of immature chick and egg-laying hen, and from different tissues of the adult male rats, exhibited a similar pattern in the presence of the inhibitor. The inhibitory effects of pyridoxal 5′-phosphate could be reversed upon exhaustive dialysis of the pyridoxan 5′-phosphate-treated acetylcholinesterase preparations. We propose that the effects of pyridoxal 5′-phosphate are due to its interaction with acetylcholinesterase, and that it can be employed as a useful tool for studying biochemical aspects of this important brain enzyme.     

The relationships between brain, serum, and whole blood ChE activity in the wood mouse (Apodemus sylvaticus) and the common shrew (Sorex araneus) after acute sublethal exposure to dimethoate

Inhibition of cholinesterase (ChE) activity produced by a single acute intraperitoneal administration of dimethoate was studied in the wood mouse, Apodemus sylvaticus, and the common shrew, Sorex araneus, under laboratory conditions. ChE values from serum and whole blood were compared with those obtained from brain in order to obtain a non-destructive tool for predicting the severity of brain acetylcholinesterase (AChE) inhibition. In addition, serum and brain inhibition following oral exposure to dimethoate was also measured in the wood mouse. Normal ChE activity was higher in the brain and whole blood of the shrews than in wood mice. There was no difference between species in serum ChE activity. Exposure to dimethoate caused a dose-dependent reduction in ChE activity and there was a significant recovery in activity with increasing time after administration. In both species, serum and whole blood were more sensitive than brain for revealing organophosphate-induced ChE inhibition and serum was more sensitive than whole blood. Statistically significant relationships were defined between whole blood and brain ChE activity and between serum and brain ChE activity. Compared with serum, whole blood ChE activity was the more accurate predictor of brain AChE levels. The relationships between brain and serum ChE activity did not appear to be affected by the route of administration of the pesticide.     

Study of some enzyme activities in cultured chick embryo brain nerve cells treated by chick embryo brain extracts

Brain extracts from 8-day-old chick embryos have been shown to influence morphological development of dissociated brain cells from 7-day-old chick embryos in culture. Stimulatory, effects on size of the neuronal somas and on growth of long processes were observed by adding the cytosol of the brain extract or the dialysate of the cytosol. These morphological changes parallel modifications of various enzyme activities according to the age of the cultures. Adenyl cyclase, (Na⁺, K⁺)- and Mg²⁺-ATPase, 5-nucleotidase, choline acetyltransferase, and acetylcholinesterase activities were studied between 5 and 14 days of culture. Adenyl cyclase activity was strongly stimulated at 8 days by both extracts. (Na⁺, K⁺)-and Mg²⁺-ATPase activities were stimulated in 8-day-old cultures only by the dialysate. 5-Nucleotidase activity was stimulated in 8-day-old cultures by the dialysate and in 11-day-old cultures by both extracts. Choline acetyltransferase activity was stimulated by the cytosol in 8-day-old cultures and by the dialysate in 11-day-old cultures. The total acetylcholinesterase activity was higher in 8-, 11-, and 14-day-old cultures treated with the cytosol. When the cells were treated with the dialysate, the activity was only higher in 14-day-old cultures. We also found that following the addition of brain extracts, the specific activity of the enzymes we studied was enhanced and became close to the values found in vivo during embryogenesis. Thus in parallel to the morphological modifications observed in nerve cell cultures treated by embryo brain extracts, biochemical variations especially involved in synaptogenesis and membrane development could be measured.     

The relationships between brain,serum, and whole blood ChE activity in the wood mouse (Apodemus sylvaticus) and the common shrew (Sorex araneus) after acute sublethal exposure to dimethoate

Abstract

Inhibition of cholinesterase (ChE) activity produced by a single acute intraperitoneal administration of dimethoate was studied in the wood mouse, Apodemus sylvaticus, and the common shrew, Sorex araneus, under laboratory conditions. ChE values from serum and whole blood were compared with those obtained from brain in order to obtain a non-destructive tool for predicting the severity of brain acetylcholinesterase (AChE) inhibition. In addition, serum and brain inhibition following oral exposure to dimethoate was also measured in the wood mouse. Normal ChE activity was higher in the brain and whole blood of the shrews than in wood mice. There was no difference between species in serum ChE activity. Exposure to dimethoate caused a dose-dependent reduction in ChE activity and there was a significant recovery in activity with increasing time after administration. In both species, serum and whole blood were more sensitive than brain for revealing organophosphate-induced ChE inhibition and serum was more sensitive than whole blood. Statistically significant relationships were defined between whole blood and brain ChE activity and between serum and brain ChE activity. Compared with serum, whole blood ChE activity was the more accurate predictor of brain AChE levels. The relationships between brain and serum ChE activity did not appear to be affected by the route of administration of the pesticide.     

Subcellular fractionation and distribution of cholinergic binding sites in fetal human brain

Conventional subcellular fractionation techniques have been applied to human fetal brain (13–15 weeks gestation) and the fractions have been characterized by assaying for marker enzymes, cholinergic binding sites and electron microscopy. Fractionation of the homogenate resulted in a nuclear pellet (P₁), a crude mitochrondrial pellet (P₂) and a supernatant (S₂). Further resolution of the P₂ fraction by density gradient centrifugation resulted in two bands at the gradient interfaces and a pellet. The P₂ and subsequently the P₂B fraction contained intact plasma membrane profiles as judged by the predominance of adenylate cyclase activity and the presence of occluded lactate dehydrogenase which constituted over 70% of the total activity in these fractions. Morphological examination of the gradient fractions revealed that the P₂B fraction contains membrane bound structures which resembie synaptosomes prepared from neonatal rat brain. These structures have a granular matrix in which mitochondria and frequently, neurofilaments were observed. Very few synaptic vesicles were present and there was no evidence for post synaptic attachments. The cholinergic markers choline acetyltransferase, acetylcholinesterase and receptor sites defined by quinuclidinyl benzilate and -bungarotoxin binding were enriched in fractions P₂ and P₂B which contained the bulk of nerve ending particles. This enriched preparation of fetal synaptosomes may be valuable for functional studies on pre-synaptic terminals in developing brain.Special Issue dedicated to Prof. Eduardo De Robertis.     

The structural and biochemical impacts of monomerizing human acetylcholinesterase

Serving a critical role in neurotransmission, human acetylcholinesterase (hAChE) is the target of organophosphate nerve agents. Hence, there is an active interest in studying the mechanism of inhibition and recovery of enzymatic activity, which could lead to better countermeasures against nerve agents. As hAChE is found in different oligomeric assemblies, certain approaches to studying it have been problematic. Herein, we examine the biochemical and structural impact of monomerizing hAChE by using two mutations: L380R/F535K. The activities of monomeric hAChE L380R/F535K and dimeric hAChE were determined to be comparable utilizing a modified Ellman's assay. To investigate the influence of subunit–subunit interactions on the structure of hAChE, a 2.1 Å X‐ray crystallographic structure was determined. Apart from minor shifts along the dimer interface, the overall structure of the hAChE L380R/F535K mutant is similar to that of dimeric hAChE. To probe whether the plasticity of the active site was overtly impacted by monomerizing hAChE, the kinetic constants of (P_R/S) ? VX (ethyl({2‐[bis(propan‐2‐yl)amino]ethyl}sulfanyl)(methyl)phosphinate) inhibition and subsequent rescue of hAChE L380R/F535K activity with HI‐6 (1‐(2′‐hydroxyiminomethyl‐1′‐pyridinium)‐3‐(4′‐carbamoyl‐1‐pyridinium)) were determined and found to be comparable to those of dimeric hAChE. Thus, hAChE L380R/F535K could be used as a substitute for dimeric hAChE when experimentally probing the ability of the hAChE active site to accommodate future nerve agent threats or judge the ability of new therapeutics to access the active site.     

Nerve agent hydrolysis activity designed into a human drug metabolism enzyme

Organophosphorus (OP) nerve agents are potent suicide inhibitors of the essential neurotransmitter-regulating enzyme acetylcholinesterase. Due to their acute toxicity, there is significant interest in developing effective countermeasures to OP poisoning. Here we impart nerve agent hydrolysis activity into the human drug metabolism enzyme carboxylesterase 1. Using crystal structures of the target enzyme in complex with nerve agent as a guide, a pair of histidine and glutamic acid residues were designed proximal to the enzyme's native catalytic triad. The resultant variant protein demonstrated significantly increased rates of reactivation following exposure to sarin, soman, and cyclosarin. Importantly, the addition of these residues did not alter the high affinity binding of nerve agents to this protein. Thus, using two amino acid substitutions, a novel enzyme was created that efficiently converted a group of hemisubstrates, compounds that can start but not complete a reaction cycle, into bona fide substrates. Such approaches may lead to novel countermeasures for nerve agent poisoning.     

Inactivation of acetylcholinesterase by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride

The neurotoxicant 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been shown to reversibly inhibit the activity of acetylcholinesterase. The inactivation of the enzyme was detected by monitoring the accumulation of yellow color produced from the reaction between thiocholine and dithiobisnitrobenzoate ion. The kinetic parameter, K _m for the substrate (acetylthiocholine), was found to be 0.216 mM and K _i for MPTP inactivation of acetylcholinesterase was found to be 2.14 mM. The inactivation of enzyme by MPTP was found to be dose-dependent. It was found that MPTP is neither a substrate of AChE nor the time-dependent inactivator. The studies of reaction kinetics indicate the inactivation of AChE to be a linear mixed-type inhibition. The dilution assays indicate that MPTP is a reversible inhibitor for AChE. These data suggest that once MPTP enters the basal ganglia of the brain, it can inactivate the acetylcholinesterase enzyme and thereby increase the acetylcholine level in the basal ganglia of brain, leading to potential cell dysfunction. It appears that the nigrostriatal toxicity by MPTP leading to Parkinson's disease-like syndrome may, in part, be mediated via the acetylcholinesterase inactivation.     

Acrylamide Influence on Activity of Acetylcholinesterase,Thiol Groups,and Malondialdehyde Content in the Brain of Swiss Mice

Acrylamide is a neurotoxin inhibiting neurotransmission in peripheral nerves. Less is known about acrylamide influence on the central nervous system. Here we measured acrylamide influence on the acetylcholinesterase activity in brain stem, hemispheres, and cerebellum of mice (males, Swiss strain) in relation to the thiol groups and malondialdehyde concentration. Acrylamide was injected intraperitoneally (20 and 40 mg/kg, i.e. 0.52 and 1.04 mg per animal). The brain structures were taken 24, 48, and 192 h after the injection. Acetylcholinesterase activity was significantly lower (p < 0.001 to p < 0.05) in all the structures. It was accompanied by the statistically significant (p < 0.001 to p < 0.05) increase in malondialdehyde concentrations in most of the studied structures time periods and ACR doses. –SH groups concentrations were significantly depleted in the right hemisphere (p < 0.01) after 24 h and in brain stem (p < 0.05) after 48 h. We suggest that neurotoxicity of acrylamide in brain is related to acetylcholinesterase inhibition and redox imbalance.