Acetylcholinesterase Activity in Rats Experimentally Demyelinated with Ethidium Bromide and Treated with Interferon Beta

The ethidium bromide (EB) demyelinating model was associated with interferon beta (IFN-β) to evaluate acetylcholinesterase (AChE) activity in the striatum (ST), hippocampus (HP), cerebral cortex (CC), cerebellum (CB), hypothalamus (HY), pons (PN) and synaptosomes from the CC. Rats were divided into four groups: I control (saline), II (IFN-β), III (EB) and IV (EB and IFN-β). After 7, 15 and 30 days rats (n = 6) were sacrificed, and the brain structures were removed for enzymatic assay. AChE activity was found to vary in all the brain structures in accordance with the day studied (7–15–30 days) (P < 0.05). In the group III, there was an inhibition of the AChE activity in the ST, CB, HY, HP and also in synaptosomes of the CC (P < 0.05). It was observed that IFN-β per se was capable to significantly inhibit (P < 0.05) AChE activity in the ST, HP, HY and synaptosomes of the CC. Our results suggest that one of the mechanisms of action of IFN-β is through the inhibition of AChE activity, and EB could be considered an inhibitor of AChE activity by interfering with cholinergic neurotransmission in the different brain regions.     

Atypical effect of some spin trapping agents: reversible inhibition of acetylcholinesterase

N-tert-butyl-alpha-phenylnitrone (PBN), a widely used nitrone-based free radical trap was recently shown to prevent acetylcholinesterase (AChE) inhibitors induced muscle fasciculations and brain seizures while being ineffective against glutamergic or cholinergic receptor agonist induced seizures. In the present study we compared the effects on AChE activity of four free radical spin traps PBN, alpha-(4-pyridil-1)-N-tert-butyl nitrone (POBN), N-tert-butyl-alpha-(2-sulfophenyl)-nitrone (S-PBN) and 5-diethoxyphosphoryl-5-methyl-1-pyrroline-N-oxide (DEPMPO). The kinetics of AChE inhibition were studied in vitro using a spectrophotometric kinetic assay with AChE from rat brain, diaphragm, electric eel and mouse brain. Spin trapping compounds S-PBN and DEPMPO, in concentrations up to 3 mM did not inhibit hydrolysis of ACh, while PBN and POBN inhibited hydrolysis of ACh in a reversible and concentration-dependent manner. Double reciprocal plots of the reaction velocity against varying ACh concentrations at each inhibitor concentration were linear and generally indicated mixed type inhibition. PBN was the most potent inhibitor of mouse AChE with Ki and Ki' of 0.58 and 2.99 mM, respectively, and the weakest inhibitor of electric eel AChE. In contrast, POBN showed the highest affinity for electric eel enzyme, with Ki and Ki' values of 1.065 and 3.15 mM, respectively. These findings suggest that the effect of PBN and POBN on AChE activity does not depend on trapping of damaging reactive oxygen and that in addition to their antioxidant action other pharmacological effects of these compounds should be considered when neuroprotective actions of PBN or POBN are investigated.     

Dual substrate model for novel approach towards a kinetic study of acetylcholinesterase inhibition by diazinon

Limited reports as compared to other insecticides appear in the literature for acetylcholinesterase (AChE) inhibition by diazinon. In the current study, new kinetic parameters of AChE inhibition by diazinon have been investigated. The assay was done with bovine retinal AChE using two different substrate (ASCh) concentrations in the absence and presence of diazinon (0.08-1.28 mM). The optical density was monitored up to 25 min (reaction time) for the assay. New kinetic parameters k'(oms), K'(sms), k(oms), K(sms), K'(asms) and K(asms) ) were calculated from these experimental data.     

The role of thyroid hormone on phenylhydrazine hydrochloride mediated inhibitory effects on blood acetylcholinesterase: an in vivo and in vitro study

A novel phenomenon of protective counteraction by thyroid hormone has been demonstrated in phenylhydrazine hydrochloride (PHH) induced insult on blood acetylcholinesterase (AChE, EC 3.1.1.7) activity, in both, in vivo and in vitro conditions. Injection of PHH (20 microg/g) to juvenile male rats for three consecutive days caused a 48% decrease (p < 0.001) in the total blood AChE activity on the third day (i.e. 24 h after injections for three consecutive days) in comparison to the control animals. Simultaneous injections of thyroxine (T4) 1 or 2 microg/g with PHH (20 microg/g) showed a recovery in AChE activity by 27% (p < 0.02) and 55% (p < 0.001), respectively, in comparison to the only PHH-injected animals. T4 at 1, 2 and 4 microg/g doses showed unchanged levels in comparison to the untreated controls. In our in vitro system, incubations of the RBCs in PHH (2 mM) containing medium also showed an inhibition of 44% (p < 0.001) of the RBC membrane AChE activity in comparison to the control conditions. A recovery of 23-81% of the enzyme activity was observed after simultaneous use of T4 (1 nM-100 nM) or T3 (0.1 nM-100 nM), or triiodothyroacetic acid (TRIAC) (100 nM) with PHH (2 mM) in a dose-dependent manner with a potency profile of T3 > T4 > TRIAC. Incubation of RBCs only with T4, T3, or TRIAC at 0.1-100 nM concentration did not cause any alteration in the membrane AChE activity in comparison to control conditions. Thus, thyroid hormone distinctly demonstrated a counteraction or protective nature of action on the PHH-induced inhibition of total blood and RBC membrane AChE activity.     

Depressed performance and detoxification enzyme activities of Helicoverpa armigera fed with conventional cotton foliage subjected to methyl jasmonate exposure

Methyl jasmonate (MeJA)‐mediated defense in conventional cotton, Gossypium hirsutum L. (Malvaceae), against cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), was investigated with respect to the activities of the detoxification enzymes acetylcholinesterase (AChE), carboxylesterase (CarE), and glutathione S‐transferases (GST) in pupae as well as the performance of larvae. The results suggested that exogenous application of MeJA to cotton leaves depressed the activities of AChE, CarE, and GST of cotton bollworm pupae. Both the absolute and protein‐specific AChE activities of pupae were depressed at all three MeJA concentrations applied as compared with a control, and the effects of 0.4 mM MeJA were significantly higher than those of 0.1 and 0.2 mM. A marked reduction in absolute CarE activity was observed at the 0.4 mM MeJA treatment, whereas the protein‐specific activity was increased by 0.2 and 0.4 mM. Absolute GST activity was significantly depressed only by the 0.4 mM MeJA treatment, whereas protein‐specific GST activity was not markedly affected by MeJA. Protein content of pupae was reduced by 0.4 mM MeJA‐induced defense in cotton leaves. The development time of larvae was protracted and pupal weight was reduced by 0.1 and 0.4 mM MeJA‐treated cotton leaves. Larval weight gain was inhibited significantly on 0.2 and 0.4 mM MeJA‐treated cotton leaves. The results suggested that MeJA‐induced plant defense may have adverse effects on H. armigera. In addition to the inhibition of growth and development, induced defense may also impair the insect's ability to detoxify toxic plant secondary metabolites.     

Characterization and use of the total head soluble cholinesterases from mosquitofish (Gambusia holbrooki) for screening of anticholinesterase activity

Inhibition of cholinesterases (ChE) has been widely used as an environmental biomarker of exposure to organophosphates (OP) and carbamate (CB) pesticides. Different ChE isoforms may be present in the same tissue and may present distinct sensitivities towards environmental contaminants. The present work characterises the soluble ChE present in mosquitofish (Gambusia holbrooki) total head homogenates, through the use of different substrates and selective inhibitors of cholinesterasic activity. Furthermore, the effects of sodium dodecylsulphate (SDS) on the enzymatic activity were investigated, both in vivo and in vitro. These results showed that acetylcholinesterase (AChE) seemed to be the predominant form present in head homogenates of G. holbrooki, despite the inhibition by tetraisopropylpyrophosphoramide (iso-OMPA) found at high concentrations. SDS was responsible for in vitro, but not in vivo, inhibitory effects. The in vitro AChE inhibitory effects of SDS was partially prevented by the use of increasing amounts of ethanol, suggesting that the inhibition was induced by an emulsion effect, which may explain the lack of effect in vivo.     

Design,synthesis and preliminary structure–activity relationship investigation of nitrogen-containing chalcone derivatives as acetylcholinesterase and butyrylcholinesterase inhibitors: a further study based on Flavokawain B Mannich base derivatives

In order to study the structure–activity relationship of Flavokawain B Mannich-based derivatives as acetylcholinesterase (AChE) inhibitors in our recent investigation, 20 new nitrogen-containing chalcone derivatives (4?a–8d) were designed, synthesized, and evaluated for AChE inhibitory activity in vitro. The results suggested that amino alkyl side chain of chalcone dramatically influenced the inhibitory activity against AChE. Among them, compound 6c revealed the strongest AChE inhibitory activity (IC₅₀ value: 0.85?μmol/L) and the highest selectivity against AChE over BuChE (ratio: 35.79). Enzyme kinetic study showed that the inhibition mechanism of compound 6c against AChE was a mixed-type inhibition. The molecular docking assay showed that this compound can both bind with the catalytic site and the peripheral site of AChE.     

Acetylcholinesterase activity in the earthworm Eisenia andrei at different conditions of carbaryl exposure

Recent reports have stressed the need for a better understanding of earthworm biomarker responses. We aimed at investigating acethylcholinesterase (AChE) activity in the earthworm Eisenia andrei after exposure to carbaryl or its commercial formulation Zoril 5 under different in vitro and in vivo experiments. In addition, lysosome membrane stability was assessed by neutral red retention assay in the same experimental conditions. AChE basal Km and Vm values were about 0.16 mM and 41 nmol min(-1) mg protein(-1), respectively. Carbaryl dose-dependently decreased Vmax, while not affecting Km values. Carbaryl reduced earthworm AChE activity within 1 day of in vivo exposure to contaminated filter paper. Tested on soil, carbaryl inhibited AChE with the maximum effect after 3 days; in contrast, lysosome membrane stability of coelomocytes indicated a maximum toxicity after one day, followed by a recovery. AChE inhibition by Zoril 5 was highest after one day, while lysosome membrane stability declined progressively. In all cases, carbaryl dose-dependently decreased Vmax while not affecting Km values. In conclusion, E. andrei AChE activity assessed in vitro is dose-dependently inhibited by the carbamate compound carbaryl, which acts as a pure competitive inhibitor. In vivo experiments suggested that pure and co-formulated carbaryl have different time and/or dose dependent effects on earthworms. Our results further support the use of AChE inhibition as an indicator of pesticide contamination, to be included in a battery of biomarkers for monitoring soil toxicity.     

The neuropeptide TRH has a minor effect on the enzymatic activity of acetylcholinesterase in vitro

The neuropeptide thyrotropin-releasing hormone (TRH) elicits a variety of physiological effects of which some are due to cholinergic mechanisms. TRH modulates in vivo the effects of compounds affecting acetylcholinesterase (AChE). In the present study the in vitro effects of TRH on the activity of AChE were explored. TRH has no effect at physiologically relevant concentrations. At unphysiologically high concentrations (>5 mM) a slight inhibition was found. This was noticed also when the enzyme was exposed to the amide-free tripeptide analog p-Glu-His-Pro. We conclude that any cholinergic effect of TRH observed in vivo is unlikely to be due to a direct interaction of the peptide with AChE.     

Environmental impact of mosquito pesticides: influence of temefos on the brain acetylcholinesterase of killifish.

Temefos and six of its metabolites were tested for their capacity to inhibit the in vitro activity of brain acetylcholinesterase (AChE) of Fundulus heteroclitus. While temefos was not inhibitory at levels up to 10.7 mM in brain homogenate samples, its metabolites were active within the range of 2 X 10(-4)mM to 1.26 mM in causing a 50% reduction in the enzyme activity. Exposure of F. heteroclitus to temefos under laboratory conditions caused a reduction in AChE activity, which was proportional to the pesticide concentration and the exposure period. Visible symptoms of organophosphate poisoning were apparent only after the AChE inhibition reached 80%. F. heteroclitus and Cyprinidon variegatus exposed to 10 biweekly applications of temefos granules in the field showed no inhibition of brain AChE. However, exposure of F. heteroclitus to biweekly applications (four) of temefos emulsion caused a reduction in the enzyme (50%), but only in the pre-third application samples. A gradual increase in brain AChE occurred both in F. heteroclitus and C. variegatus as the season progressed from April to October.     

The preparation, in vitro screening and molecular docking of symmetrical bisquaternary cholinesterase inhibitors containing a but-(2E)-en-1,4-diyl connecting linkage

Carbamate inhibitors (e.g. pyridostigmine bromide) are used as a pre-treatment for the prevention of organophosphorus poisoning. They work by blocking the native function of acetylcholinesterases (AChE) and thus protect AChE against irreversible inhibition by organophosphorus compounds. However, carbamate inhibitors are known for their many undesirable side effects related to the carbamylation of AChE. In this paper, we describe 17 novel bisquaternary compounds and have analysed their effect on AChE inhibition. The newly prepared compounds were evaluated in vitro using both human erythrocyte AChE and human plasmatic butyrylcholinesterase. Their inhibitory ability was expressed as the half maximal inhibitory concentration (IC??) and then compared to the standard carbamate drugs and two AChE reactivators. One of these novel compounds showed promising AChE inhibition in vitro (nM range) and was better than the currently used standards. Additionally, a kinetic assay confirmed the non-competitive inhibition of hAChE by this novel compound. Consequently, the docking results confirmed the apparent π-π or π-cationic interactions with the key amino acid residues of hAChE and the binding of the chosen compound at the enzyme catalytic site.     

Insulin Mimetic Effect of Tungsten Compounds on Isolated Rat Adipocytes

Investigations of effective, orally active, and safe antidiabetic metallopharmaceuticals have been carried out during the last two decades. It has been reported that tungsten compounds mimic the action of insulin in intact cell systems. As insulin mimetics, the most investigated tungsten compound was sodium tungstate (ST), rarely investigated was tungstophosphoric acid (WPA), but never alanine complex of tungstophosphoric acid (WPA-A). In this study, the insulin mimetic activity of three different tungsten compounds, ST, WPA, and WPA-A, was evaluated by means of in vitro measurements of the glucose uptake and inhibition of free fatty acids release from epinephrine-treated isolated rat white adipocytes. We investigated the influence of concentration (lower and higher, 0.1 and 1.0 mM, respectively) and solvent: isotonic salt solution—saline (0.9% w/v of NaCl) and dimethyl sulfoxide (DMSO; 2% v/v), on the biological effect of tested compounds. Our experimental data showed that all of the three investigated tungsten compounds possess insulin mimetic activity in vitro on the isolated adipocytes. Influence of concentration and solvents on insulin mimetic effect for the certain tungsten compounds were: WPA was shown effect independently of concentration and solvents; higher concentration and DMSO were significant decreasing insulin mimetic effect of ST; lower concentration and saline led to decreasing effect of WPA-A. Generally, there were no differences in insulin mimetic effect of three tungsten compounds in lower concentration and dissolved in DMSO. When saline was used as solvent, it was needed higher concentration of investigated compounds to accomplish the same effect. In conclusion, our results suggest that low concentration (0.1 mM) of ST, WPA, and WPA-A dissolved in 2% DMSO could be the good candidates for in vivo investigation of their antidiabetic properties.     

Novel coumarin derivatives as potent acetylcholinesterase inhibitors: insight into efficacy,mode and site of inhibition

The inhibitory efficacy of two substituted coumarin derivatives on the activity of neurodegenerative enzyme acetylcholinesterase (AChE) was assessed in aqueous buffer as well as in the presence of human serum albumin (HSA) and compared against standard cholinergic AD drug, Donepezil (DON). The experimental data revealed the inhibition to be of non-competitive type with both the systems showing substantial inhibitory activity on AChE. In fact, one of the tested compounds Chromenyl Coumarate (CC) was found to be better inhibitor (IC₅₀ = 48.49 ± 5.6 nM) than the reference drug DON (IC₅₀ = 74.13 ± 8.3 nM), unequivocally amplifying its importance. The structure of the compound was found to play a vital role in the inhibitory efficiency, validating previous Structure Activity Relationship (SAR) reviews for coumarin. The mechanism of inhibition remained impervious when the experimental medium was switched from aqueous buffer to HSA, albeit noticeable change in the inhibition potency of the compound 3, 3′- Methylene-bis (4-hydroxy coumarin) (MHC) (38%) and CC (35%). Both the coumarin derivatives were observed to bind to the peripheral anionic site (PAS) of AChE and also found to displace the fluorescence marker thioflavinT (ThT) from AChE binding pocket. All experimental observations were seconded by molecular docking and MD simulation results. The inferences drawn in this study form a foundation for further investigation on these compounds; magnifying the probability of their usage as AD drugs and re-emphasizes the significance of drug delivery media while considering the inhibition potencies of targeted drugs.     

Some new carbacylamidophosphates as inhibitors of acetylcholinesterase and butyrylcholinesterase

The differences in the inhibition activity of organophosphorus agents are a manifestation of different molecular properties of the inhibitors involved in the interaction with the active site of enzyme. We were interested in comparing the inhibition potency of four known synthesized carbacylamidophosphates with the general formula RC(O)NHP(O)Cl2, constituting organophosphorus compounds, where R = CCl3 (1), CHCl2 (2), CH2Cl (3) and CF3 (4), and four new ones with the general formula RC(O)NHP(O)(R')2, where R' = morpholine and R = CCl3 (5), CHCl2 (6), CH2Cl (7), CF3 (8), on AChE and BuChE activities. In addition, in vitro activities of all eight compounds on BuChE were determined. Besides, in vivo inhibition potency of compounds 2 and 6, which had the highest inhibition potency among the tested compounds, was studied. The data demonstrated that compound 2 from the compound series 1 to 4 and compound 6 from the compound series 5 to 8 are the most sensitive as AChE and BuChE inhibitors, respectively. Comparing the IC50 values of these compounds, it was clear that the inhibition potency of these compounds for AChE are 2- to 100-fold greater than for BuChE inhibition. Comparison of the kinetics (IC50, Ki, kp, KA and KD) of AChE and BuChE inactivation by these compounds resulted in no significant difference for the measured variables except for compounds 2 and 6, which appeared to be more sensitive to AChE and BuChE by significantly higher kp and Ki values and a lower IC50 value in comparison with the other compounds. The LD50 value of compounds 2 and 6, after oral administration, and the changes of erythrocyte AChE and plasma BuChE activities in albino mice were studied. The in vivo experiments, similar to the in vitro results, showed that compound 2 is a stronger AChE and BuChE inhibitor than the other synthesized carbacylamidophosphates. Furthermore, in this study, the importance of electropositivity of the phosphorus atom, steric hindrance and leaving group specificity were reinforced as important determinants of inhibition activity.     

Microplate biochemical determination of Russian VX: influence of admixtures and avoidance of false negative results

Two microplate spectroscopic methods for determination of organophosphates, based on inhibition of acetylcholinesterase (AChE) activity, were further improved and evaluated for determination of the chemical weapon agent Russian VX (RVX) in aqueous solutions. The linear range of the Hestrin method (74.8-1120 pM) was 3.1-fold wider than that of the Ellman method (37.4-374 pM). Limits of detection and quantification of RVX for both methods were below the maximal allowable concentration of RVX in water-soluble washouts. One of the early products of RVX hydrolysis, N,N-diethylaminoethanethiol, like reduced glutathione, caused false negative results in the Ellman method at concentrations exceeding 10 μM; individual blanks were necessary to eliminate the effect. The Hestrin method showed greater specificity (~3 orders of magnitude) for analysis of samples containing mercaptans. A major product of RVX degradation, 2,2'-dithiobis(N,N-diethylethanamine), caused significant inhibition of AChE at concentrations of ≥0.1 mM (P<0.01) and had a false positive effect at higher concentrations (≥2 mM). For environmental monitoring of RVX, the method based on Hestrin is preferred over that based on Ellman, principally because the former method was less sensitive to interference from major admixtures and did not give rise to potentially dangerous false negative results.     

The effect of galactose metabolic disorders on rat brain acetylcholinesterase activity

To evaluate whether in classical galactosemia galactose (Gal), galactose-1-phosphate (Gal-1-P) and galactitol (Galtol) affect brain acetylcholinesterase (AChE) activity, various concentrations (1-16 mM) of these compounds were preincubated with brain homogenates of suckling rats as well as with pure eel Electroforus electricus AChE at 37 degrees C for 1 h. Initially, Galtol (up to 2.0 mM) increased (25%) AChE activity which decreased. thereafter, reaching the control value in high Galtol concentrations. Gal-1-P decreased gradually the enzyme activity reaching a plateau (38%), when incubated with 8-16 mM. However, when the usually found 2 mM of Galtol and 2 mM of Gal-1-P, concentrations in galactosemia were added in the incubation mixture simultaneously, brain AChE was stimulated (16%). Galtol or Gal-1-P modulated brain AChE as well as enzyme activity of E.electricus in the same way. Gal, Glucose (Glu) and glucose-1-phosphate (Glu-1-P) had no effect on AChE activity. It is suggested that Galtol as well as Gal-1-P can affect acetylcholine degradation acting directly on AChE molecule. Consequently the direct action of these substances on the enzyme might explain the brain cholinergic dysfunction in untreated galactosemia patients.     

The Binding Mechanisms and Inhibitory Effect of Intravenous Anesthetics on AChE In Vitro and In Vivo: Kinetic Analysis and Molecular Docking

Inhibitors of acetylcholinesterase (AChE), which have an important role in the prevention of excessive AChE activity and β-amyloid (Aβ) formation are widely used in the symptomatic treatment of Alzheimer's disease (AD). The inhibitory effect of anesthetic agents on AChE was determined by several approaches, including binding mechanisms, molecular docking and kinetic analysis. Inhibitory effect of intravenous anesthetics on AChE as in vitro and in vivo have been discovered. The midazolam, propofol and thiopental have shown competitive inhibition type (midazolam > propofol > thiopental) and Ki values were found to be 3.96.0 ± 0.1, 5.75 ± 0.12 and 29.65 ± 2.04 µM, respectively. The thiopental and midazolam showed inhibition effect on AChE in vitro, whereas they showed activation effect in vivo when they are combined together. The order of binding of the drugs to the active site of the 4M0E receptor was found to be midazolam > propofol > thiopental. This study on anesthetic agents that are now widely used in surgical applications, have provided a molecular basis for investigating the drug-enzyme interactions mechanism. In addition, the study is important in understanding the molecular mechanism of inhibitors that are effective in the treatment of AD.

     

Investigation of biological activities of various 1,2,3-triazole compounds: Their effects on cholinesterase enzymes,determination of antioxidant capacity and antimicrobial activity

1,2,3-triazoles are pharmaceutically significant compounds that have attracted recent interest from medicinal chemists because of their important biological activities. Addressed herein, some 1,2,3-triazoles were synthesized to investigate the inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes, antioxidant capacity, and antimicrobial effect. The antioxidant profile of 1,2,3-triazoles determined by varied bioanalytical antioxidant methods, including 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS^.+), 1,1-diphenyl-2-picrylhydrazil (DPPH·), cupric ion (Cu²⁺) and ferric ion (Fe³⁺) ascorbic acid, butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) were used as the standard compounds. In addition, the antibacterial and antifungal activities of these compounds were investigated against seven bacteria and three fungal species using the hollow agar method. As a result of these studies, it was determined that compound 4 showed the best antimicrobial activity and antioxidant activity close to the standards. Inhibitory effects and kinetic studies of these molecules on cholinesterase enzymes were performed. According to the results obtained, compound 4 showed stronger AChE inhibition and compound 3 stronger BChE inhibition compared to other compounds. In kinetic studies, it was found that AChE showed noncompetitive inhibition by compound 4, and BChE showed competitive inhibition by compound 3.     

17-β estradiol in the acetylcholinesterase activity and lipid peroxidation in the brain and blood of ovariectomized adult and middle-aged rats

AimsTo investigate the 17-β estradiol in the acetylcholinesterase activity and lipid peroxidation in the brain and blood of ovariectomized rats of different ages.Main methodsAnimals were randomly assigned into three experimental groups of each age (n = 6). Control groups consisted of adult (sham-A) and middle-aged (sham-MA) female rats, ovariectomized adult (OVX-A) and middle-aged (OVX-MA) rats without estrogen therapy reposition, and ovariectomized adult (OVX + E2-A) and middle-aged (OVX + E2-MA) rats treated with 17-β estradiol for 30 days. After this period, AChE activity and lipid peroxidation were measured in the brain and blood.Key findingsThe AChE activity increased (p < 0.05) in striatum (ST) in OVX-A, OVX + E2-A and OVX-MA, and hippocampus (HP) in OVX-MA. The enzyme activity decreased (p < 0.05) in ST of OVX + E2-MA, and cerebral cortex (CC) in OVX + E2-A, OVX-MA and OVX + E2-MA. Blood AChE activity increased (p < 0.05) in OVX + E2-A and decreased (p < 0.05) in OVX-MA. Lymphocyte AChE activity increased (p < 0.05) in OVX-A and OVX + E2-A and decreased (p < 0.05) in OVX-MA. Lipid peroxidation increased (p < 0.05) in ST of OVX-A, CC of OVX-A and OVX-MA, HP of OVX-A, and cerebellum (CE) of OVX-A, OVX-MA, and OVX + E2-MA. Lipid peroxidation decreased (p < 0.05) in ST, CC and CE of OVX + E2-A, and ST and HP of OVX + E2-MA. Similar values of lipid peroxidation to control groups were found in ST and HP of OVX-MA, HP of OVX + E2-A and CC of OVX + E2-MA.Significance17-β estradiol is able to modulate the AChE activity and non-neuronal cholinergic response as well as to reduce lipid peroxidation. Its response is dependent on the age and brain structure analyzed.