Acetylcholinesterase Activity In Rat Brain Research Articles

In silico screening, TLC bioautography and in vivo studies of Zanthoxylum armatum DC. (Indian Prickly Ash) extract as a potential neuroprotective agent

Zanthoxylum armatum DC., a popular spice, and folklore medicine, is widely distributed throughout the Northeastern region of India and practiced by indigenous tribes as a remedy for digestive and nervous system disorders. The study aimed to assess the neuro-protective potentiality of Zanthoxylum armatum extract through different learning and memory paradigms against scopolamine-induced cognitive impairment. For the isolation of the compounds, coarsely powdered shade-dried fruits were extracted with ethanol by the cold maceration method. In silico studies were performed for the isolated compounds. TLC bioautographic enzyme assay was developed to screen acetylcholinesterase and butyrylcholinesterase inhibition by plant extract using donepezil, a known acetylcholinesterase inhibitor. Memory retention activities of ethanolic extract (100, 200, and 400 mg/kg; p.o.) were determined in-vivo , along with an estimation of whole-brain cholinesterase and antioxidant activity. Chromatographic analysis from chloroform fraction resulted in the isolation of three bio-active phytoconstituents, and structural elucidation identified them as β-sitosterol (ZA-01), Stigmasterol (ZA-02), and Lupeol (ZA-03). In silico molecular docking studies revealed stigmasterol has the minimum binding energy with acetylcholinesterase among all the isolated bioactive. The stability of the protein-ligand complex was found satisfactory after performing molecular dynamics simulation studies. Pre-treatment with extract significantly improved transfer latency in maze tests decreased rat brain acetylcholinesterase activity, and showed antioxidant potentiality against scopolamine-induced memory impairment. The combination of neuroprotective, anticholinesterase, and antioxidant effects shown by Z. armatum extract may be what makes it a nootropic drug. These are good signs for the search for natural nootropics from Z. armatum extract. Even so, more research with extracts and isolated compounds will be needed to make the traditional uses of the plant more scientifically sound. • Zanthoxylum armatum is evaluated for its potential as neuroprotective agent. • β-sitosterol, Stigmasterol and Lupeol were isolated from the plant extract. • In silico molecular docking and molecular dynamics simulations were performed. • TLC bioautography, in vivo animal tests showed good neuroprotective action of Zanthoxylum armatum extract.

Antiamnesic Potential of <i>Coccinia indica</i> (Linn.) Extract: A Mechanism Based Study

Coccinia indica Linn., a well explored traditional edible medicinal plant of North East region of India, is routinely used as folkloric medicine to treat neurological disorders associated with cognitive dysfunction. The objective of the study was to evaluate the antiamnesic activity of Coccinia indica fruit extract. Antiamnesic activity of Coccinia indica was studied in Elevated plus maze and Y-maze against scopolamine induced amnesia. Moreover, we studied the influence of Coccinia indica extract on whole brain acetyl cholinesterase enzyme. Ethanolic extracts of Coccinia indica (100, 200 and 400 mg/kg body weight) were administered to healthy adult Wistar rats for successive seven days and acquisition, retention and retrieval of spatial recognition memory was determined against scopolamine (1 mg/kg, i.p.) induced amnesia in-vivo. Further, whole brain acetylcholinesterase was estimated as per Elman’s method. Pre-treatment with Coccinia indica ethanolic extract significantly improved spatial learning and memory and decreased rat brain acetyl cholinesterase activity in a dose dependent manner and comparable with standard drug Donepezil. The results indicate that ethanolic extract of Coccinia indica might be a useful as natural source of antiamnesic drug to improve learning and memory deficit associated symptoms of dementia and Alzheimer’s patients.

In Vitro Effects of 2-{4-[Methylthio(methylsulfonyl)]phenyl}-3-substitutedthiazolidin-4-ones on the Acetylcholinesterase Activity in Rat Brain and Lymphocytes: Isoform Selectivity, Kinetic Analysis, and Molecular Docking.

This work evaluated the in vitro effect of thiazolidin-4-ones on the activity of AChE (total and isoforms) isolated from the cerebral cortex, hippocampus, and lymphocytes. Kinetic parameters were evaluated and molecular docking was performed. Our results showed that thiazolidinones derived from 4-(methylthio)benzaldehyde (1) and from 4-(methylsulfonyl)benzaldehyde (2) were capable of inhibiting the AChE activity in vitro. Three compounds, two with a propylpiperidine (1b and 2b) moiety and one with a 3-(diethylamino)propyl (1c) moiety showed IC50 values of 13.81μM, and 3.13μM (1b), 55.36μM and 44.33μM (1c) for cerebral cortex and hippocampus, respectively, and 3.11μM for both (2b). Enzyme kinetics revealed that the type of AChE inhibition was mixed. Compound 1b inhibited the G1 and G4 AChE isoforms, while compounds 1c and 2b selectively inhibited the G4 isoform. Molecular docking showed a possible three-dimensional fit into the enzyme. Our findings showed that these thiazolidin-4-ones, especially those containing the propylpiperidine core, have a potential cholinesterase inhibitory activity and can be considered good candidates for future Alzheimer's therapy.

Physical enrichment enhances memory function by regulating stress hormone and brain acetylcholinesterase activity in rats exposed to restraint stress

To study the effects of stress on mental health activity is of great importance in neuropsychological studies as it may affect the lifelong performance related to brain and overall health and wellbeing of an individual. It is observed very often that exposure to stress during early life can alter the brain function which may reflect as cognitive disability. Impairment of memory is associated with increased oxidative stress which is due to enhanced production of free radicals that may lead to lipid peroxidation and disintegration of cell structure and functions. Exposure to enriched environment has shown to enhance spatial learning and memory, although the underlying mechanism covering the regulation of antioxidant capacity is limited. Here we investigated short and long term memory using Morris water maze before and after giving restraint stress procedure in rats exposed to social and physically enriched environment. Levels of malondialdehyde (MDA), activity of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and acetylcholinesterase (AChE) in brain tissue were estimated. Plasma corticosterone was also determined after decapitation. Results demonstrated that rats pre-exposed to physical along with social enrichment showed improved short and long term memory as compared to control group. However, restraint stress exerted differential effects in socially and physically enriched groups. Reduced lipid peroxidation and decreased activity of SOD, GPx and AChE were observed in physically enriched rats subjected to stress as compared to stressed rats kept in social environment. Levels of corticosterone were also found to be significantly reduced in rats kept in physically enriched environment. This study shows the beneficial effects of environmental enrichment on learning and spatial memory by reducing oxidative stress via reducing lipid peroxidation and regulation of antioxidant enzymes in rats.

Cytoglobin, neuroglobin, and acetylcholinesterase activity in rat brain as adaptation responses to intermittent hypobaric hypoxia

Background: Intermittent hypobaric hypoxia is suggested to possess a protective effect toward the hypoxic condition. The aim of this study is to analyze the expression of cytoglobin (Cygb), neuroglobin (Ngb) and the specific activity of acetylcholinesterase (AChE) in brain tissue as adaptive responses to intermittent hypobaric hypoxia. Methods: Twenty-five adult Sprague-Dawley male rats were divided into 5 groups: 1) The control group (normoxia); 2) group exposed to acute hypobaric hypoxia (AHH); 3) group exposed to hypobaric hypoxia (HH) on day-1 and re-exposed on day-8 (intermittent hypobaric hypoxia once or IHH1x); 4) group that is exposed to HH on day-1, re-exposed to HH on day-8 and day-15 (intermittent hypobaric hypoxia two times or IHH2x); 5) group exposed to HH on day-1, re-exposed to HH on day-8, day-15 and day-22 (intermittent hypobaric hypoxia 3x or IHH3x). Homogenized brain tissue was then measured and analyzed for Cygb and Ngb protein expression, and also AChE specific activity. Results: Cytoglobin and Ngb were decreased in the acute induction and increased significantly along with the increasing frequency of the IHH induction. There were significant differences in Cygb expression between IHH2x and IHH3x groups compared to normoxia group, and between IHH1x, IHH2x and IHH3x compared to AHH group. There were significant differences in Ngb expression between IHH2x and IHH3x groups compared to normoxia group and between IHH2x and IHH3x groups compared to AHH group. The specific activity of AChE was increased significantly since the first induction of AHH, but then decreased in IHH3x. There were significant differences in the specific activity of AChE between IHH2x and IHH3x groups compared to normoxia and between IHH2x and IHH3x groups compared to IHH1x groups. Conclusions: We conclude that IHH, especially IHH3x, seems to induce the protective adaptive response in the rat brain tissue through the changes of these three parameters.

Exploring the Effect of Chronic Exposure to Radio-Frequency Electromagnetic Radiation on Neurotransmitters and Acetylcholinesterase activity in rat Brain

Today there is an upsurge in the public and media concern about the potential health risk of radiofrequency field exposure. Interaction of radio frequency electromagnetic radiation with the brain is a precarious apprehension in our society. The current study was aimed to evaluate the possible implications on neurotransmitter and AChE activity levels on exposure to radio frequency-electromagnetic radiation (RF-EMR) in male rats at 900 MHz and 1800 MHz frequencies for 2 h per day for 3 months. Wistar rats were categorised into three groups (n=6) viz., sham exposure, exposure to 1800 MHz and exposure to 900 MHz. At the end of the study alterations in neurotransmitters level and histopathology of brain were analysed. The brain level of dopamine, nor-adrenaline, GABA and AChE enzyme activity was found to be significantly lowered. Histopathological findings of brain showed a marked congestion of the cerebral blood vessels and few of the pyramidal cells and neuroglial cells show degenerative changes with mild inflammatory infiltration. Thus, our results suggest that exposure to RF-EMR certainly causesinhibition of AChE activity, alteration in brain transmitter levels and changes in the architecture of brain parenchymal tissue.

Chlorpyrifos pollution: its effect on brain acetylcholinesterase activity in rat and treatment of polluted soil by indigenous Pseudomonas sp.

The study was aimed to evaluate the levels of chlorpyrifos (CPF) pollution in agricultural soil of Punjab, India, its detrimental effects on acetylcholinesterase (AChE) activity in rat brain and bioremediation of soils polluted with CPF using indigenous and adapted bacterial lab isolate. The analysis revealed that soil samples of Bathinda and Amritsar regions are highly contaminated with chlorpyrifos showing 19 to 175mg/kg concentrations of CPF. The non-targeted animals may get poisoned with CPF by its indirect dermal absorption, inhalation of toxic fumes and regular consumption of soiled food grains. The study indicated that even the lowermost concentrations of CPF, 19 and 76mg/kg of soil found in the Amritsar and Bathinda regions respectively can significantly inhibit the AChE activity in rat brain within 24h of its treatment. This represents the antagonistic effect of CPF on AChE which is a prime neurotransmitter present in all living beings including humans. In light of this, an attempt was made to remediate the polluted soil, a major reservoir of CPF, using Pseudomonas sp. (ChlD), an indigenous bacterial isolate. The culture efficiently degraded 10 to 100mg/kg chlorpyrifos supplemented in the soil and utilized it as sole source of carbon and energy for its growth. Thus, this study provides a detailed insight regarding the level of CPF pollution in Punjab, its detrimental effects on mammals and bio-based solution to remediate the sites polluted with CPF.

Nootropic activity of Crataeva nurvala Buch-Ham against scopolamine induced cognitive impairment.

Loss of cognition is one of the age related mental problems and a characteristic symptom of neurodegenerative disorders like Alzheimer’s. Crataeva nurvala Buch-Ham, a well explored traditional Indian medicinal plant of Westernghats, is routinely used as folkloric medicine to treat various ailments in particular urolithiasis and neurological disorders associated with cognitive dysfunction. The objective of the study was to evaluate the nootropic activity of Crataeva nurvala Buch-Ham stem bark in different learning and memory paradigm viz. Elevated plus maze and Y-maze against scopolamine induced cognitive impairment. Moreover, to elucidate possible mechanism, we studied the influence of Crataeva nurvala ethanolic extract on central cholinergic activity via estimating the whole brain acetyl cholinesterase enzyme. Ethanolic extracts of Crataeva nurvala (100, 200 and 400 mg/kg body weight) were administered to adult Wistar rats for successive seven days and the acquisition, retention and retrieval of spatial recognition memory was determined against scopolamine (1 mg/kg, i.p.) induced amnesia through exteroceptive behavioral models viz. Elevated plus maze and Y-maze models. Further, whole brain acetyl cholinesterase enzyme was estimated through Ellman’s method. Pretreatment with Crataeva nurvala ethanolic extract significantly improved spatial learning and memory against scopolamine induced amnesia. Moreover, Crataeva nurvala extract decreased rat brain acetyl cholinesterase activity in a dose dependent manner and comparable to the standard drug Piracetam. The results indicate that ethanolic extract of Crataeva nurvala might be a useful as nootropic agent to delay the onset and reduce the severity of symptoms associated with dementia and Alzheimer’s disease. The underlying mechanism of action of its nootropic potentiality might be attributed to its anticholinesterase property.

In vivo and in vitro effects of fructose on rat brain acetylcholinesterase activity: an ontogenetic study.

Increased fructose concentrations are the biochemical hallmark of fructosemia, a group of inherited disorders on the metabolic pathway of this sugar. The main clinical findings observed in patients affected by fructosemia include neurological abnormalities with developmental delay, whose pathophysiology is still undefined. In the present work we investigated the in vitro and in vivo effects of fructose on acetylcholinesterase (AchE) activity in brain structures of developing rats. For the in vitro experiments, fructose was added at increasing concentrations to the incubation medium. It was observed that fructose provoked an inhibition of acetylcholinesterase activity in cerebral cortex of 30-day-old-rats, even at low concentrations (0.1 mM). For the in vivo experiments, rats were killed 1 h after a single fructose administration (5 µmol/g). Control group received the same volume of saline solution. We found that AchE activity was increased in cerebral cortex of 30- and 60-day-old rats receiving fructose administration. Finally, we observed that AchE activity was unaffected by acute fructose administration in cerebral cortex, striatum or hippocampus of 15- and 90-day-old rats. The present data suggest that a disruption in cholinergic homeostasis may be involved in the pathophysiology of brain damage observed in young patients affected by fructosemia.

Rosmarinus officinalis L. leaf extract improves memory impairment and affects acetylcholinesterase and butyrylcholinesterase activities in rat brain

Rosmarinus officinalis L. leaf as part of a diet and medication can be a valuable proposal for the prevention and treatment of dementia. The aim of the study was to assess the effects of subchronic (28-fold) administration of a plant extract (RE) (200mg/kg, p.o.) on behavioral and cognitive responses of rats linked with acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activity and their mRNA expression level in the hippocampus and frontal cortex. The passive avoidance test results showed that RE improved long-term memory in scopolamine-induced rats. The extract inhibited the AChE activity and showed a stimulatory effect on BuChE in both parts of rat brain. Moreover, RE produced a lower mRNA BuChE expression in the cortex and simultaneously an increase in the hippocampus. The study suggests that RE led to improved long-term memory in rats, which can be partially explained by its inhibition of AChE activity in rat brain.

Short-Term Exposure to Nickel Alters the Adult Rat Brain Antioxidant Status and the Activities of Crucial Membrane-Bound Enzymes: Neuroprotection by L-Cysteine

Nickel (Ni) is an environmental pollutant towards which human exposure can be both occupational (mainly through inhalation) and dietary (through water and food chain-induced bioaccumulation). The aim of this study was to investigate the effects of short-term Ni-administration (as NiCl(2), 13mg/kg) on the adult rat whole brain total antioxidant status (TAS) and the activities of acetylcholinesterase (AChE), Na(+),K(+)-ATPase, and Mg(2+)-ATPase; in addition, the potential effect of the co-administration of the antioxidant L-cysteine (Cys, 7mg/kg) on the above parameters was studied. Twenty-eight male Wistar rats were divided into four groups: A (saline-treated control), B (Ni), C (Cys), and D (Ni and Cys). All rats were treated once daily with intraperitoneal injections of the tested compounds, for 1-week. Rats were sacrificed by decapitation and the above-mentioned parameters were measured spectrophotometrically. Rats treated with Ni exhibited a significant reduction in brain TAS (-47%, p < 0.001, BvsA) that was efficiently limited by the co-administration of Cys (-4%, p > 0.05, DvsA; +83%, p < 0.001, DvsB), while Cys (group C) had no effect on TAS. The rat brain AChE activity was found significantly increased by both Ni (+30%, p < 0.001, BvsA) and Cys (+62%, p < 0.001, CvsA), while it tended to adjust to control levels by the co-administration of Ni and Cys (+13%, p < 0.001, DvsA; -13%, p < 0.001, DvsB). The activity of rat brain Na(+),K(+)-ATPase was significantly decreased by Ni-administration (-49%, p < 0.001, BvsA), while Cys supplementation could not reverse this decrease (-44%, p < 0.001, DvsA). The activity of Mg(2+)-ATPase was not affected by Ni-administration (-3%, p > 0.05, BvsA), but was significantly reduced when combined with Cys administration (-17%, p < 0.001, DvsA). The above findings suggest that Ni short-term in vivo administration causes a statistically significant decrease in the rat brain TAS and an increase in AChE activity. Both effects can be, partially or totally, reversed to control levels by Cys co-administration; Cys could thus be considered (for future applications) as a potential neuroprotective agent against chronic exposure to Ni. The activity of Na(+),K(+)-ATPase that was inhibited by Ni, could not be reversed by Cys co-administration. The matter requires further investigation in order to fully elucidate the spectrum of the neurotoxic effects of Ni.

A 1-methyl-4-piperidinyl cytectrene carboxylate labeled by the technetium 99m, a radiotracer for rat brain acetylcholinesterase activity

Alzheimer's disease (AD) is a degenerative neurological disorder that causes progressive and irreversible loss of connections between brain cells and loss of mental functions. Clinical and postmortem studies show that the biochemical changes in brains of AD patients include decrease in acetylcholinesterase (AChE) activity. Our aim was to study AChE activity using piperidinyl ester labelled with technetium-99m. In vivo and in vitro studies demonstrated that labelled piperidinyl ester was a substrate for AChE. The hydrolytic rate of this substrate was measured and the specificity was evaluated using the inhibitor BW284c51. The rhenium analogues of the technetium-labelled substrate were used to determine the affinity constant (K(m)) and the maximum reaction velocity (V(max)) because of the high specific activity of technetium. The high hydrolytic rate and high specificity of the substrate for AChE make it suitable as an in vivo radiotracer for studying AChE activity in the brain.

Combined thirty-day exposure to thioacetamide and choline-deprivation alters serum antioxidant status and crucial brain enzyme activities in adult rats

Choline (Ch) is an essential nutrient that seems to be involved in a wide variety of metabolic reactions and functions that affect the nervous system, while thioacetamide (TAA) is a well-known hepatotoxic agent. The induction of prolonged Ch-deprivation (CD) in rats receiving TAA (through the drinking water) provides an experimental model of mild progressive hepatotoxicity that could simulate commonly-presented cases in clinical practice. In this respect, the aim of this study was to investigate the effects of a 30-day dietary CD and/or TAA administration (300 mg/L of drinking water) on the serum total antioxidant status (TAS) and the activities of brain acetylcholinesterase (AChE), Na(+),K(+)-ATPase and Mg(2+)-ATPase of adult rats. Twenty male Wistar rats were divided into four groups: A (control), B (CD), C (TAA), D (CD+TAA). Dietary CD was provoked through the administration of Ch-deficient diet. Rats were sacrificed by decapitation at the end of the 30-day experimental period and whole brain enzymes were determined spectrophotometrically. Serum TAS was found significantly lowered by CD (-11% vs Control, p < 0.01) and CD+TAA administration (-19% vs Control, p < 0.001), but was not significantly altered due to TAA administration. The rat brain AChE activity was found significantly increased by TAA administration (+11% vs Control, p < 0.01), as well as by CD+TAA administration (+14% vs Control, p < 0.01). However, AChE was not found to be significantly altered by the 30-day dietary CD. On the other hand, CD caused a significant increase in brain Na(+),K(+)-ATPase activity (+16% vs Control, p < 0.05) and had no significant effect on Mg(2+)-ATPase. Exposure to TAA had no significant effect on Na(+),K(+)-ATPase, but inhibited Mg(2+)-ATPase (-20% vs Control, p < 0.05). When administered to CD rats, TAA caused a significant decrease in Na(+),K(+)-ATPase activity (-41% vs Control, p < 0.001), but Mg(2+)-ATPase activity was maintained into control levels. Our data revealed that an adult-onset 30-day dietary-induced CD had no effect on AChE activity. Treatment with TAA not only reversed the stimulatory effect of CD on adult rat brain Na(+),K(+)-ATPase, but caused a dramatic decrease in its activity (-41%). Previous studies have linked this inhibition with metabolic phenomena related to TAA-induced fulminant hepatic failure and encephalopathy. Our data suggest that CD (at least under the examined 30-day period) is an unfavorable background for the effect of TAA-induced hepatic damage on Na(+),K(+)-ATPase activity (an enzyme involved in neuronal excitability, metabolic energy production and neurotransmission).

The neuroprotective role of l-cysteine towards the effects of short-term exposure to lanthanum on the adult rat brain antioxidant status and the activities of acetylcholinesterase, (Na+,K+)- and Mg2+-ATPase

Lanthanum (La) is a rare earth element that is widely used for industrial, medical and agricultural purposes. Its neurotoxic effects are linked to its physical and chemical properties and its interaction with certain trace elements and membrane-bound enzymes. The aim of this study was to investigate the effects of short-term La-administration (as LaCl(3), 53 mg/kg) on the adult rat whole brain total antioxidant status (TAS) and the activities of acetylcholinesterase (AChE), Na(+),K(+)-ATPase and Mg(2+)-ATPase, as well as the potential effect of the co-administration of the antioxidant L: -cysteine (Cys, 7 mg/kg) on the above parameters. Twenty-eight male Wistar rats were divided into four groups: A (saline-treated control), B (La), C (Cys),and D (La and Cys). All rats were treated once daily with intraperitoneal injections of the tested compounds, for 1-week. Rats were sacrificed by decapitation and the above mentioned parameters were measured spectrophotometrically. Rats treated with La exhibited a significant reduction in brain TAS (-36%, P < 0.001, BvsA), that was partially limited by the co-administration of Cys (-13%, P < 0.01, DvsA), while Cys (group C) had no effect on TAS. The rat brain AChE activity was found significantly increased by both La (+23%, P < 0.001, BvsA) and Cys (+59%, P < 0.001, CvsA), while it was adjusted to control levels by the co-administration of La and Cys. The activity of rat brain Na(+),K(+)-ATPase was significantly decreased by La-administration (-28%, P < 0.001, BvsA), while Cys supplementation could not reverse this decrease. The activity of Mg(2+)-ATPase exhibited a slight but statistically significant reduction due to La (-8%, P < 0.01, BvsA), that was further reduced by Cys co-administration (-25%, P < 0.001, DvsA). The above findings suggest that La short-term in vivo administration causes a statistically significant decrease in the rat brain TAS and an increase in AChE activity. Both effects can be, partially or totally, reversed into control levels by Cys co-administration, which could thus be considered for future applications as a neuroprotective agent against chronic exposure to La. The activities of Na(+),K(+)- and Mg(2+)-ATPase that were inhibited by La, could not be reversed by Cys co-administration. A role for the already reported concentration-dependent interaction of La with Ca-binding sites (such as Ca(2+)-ATPase) might be considered for certain of the above phenomena.

Influence of LPS-induced neuroinflammation on acetylcholinesterase activity in rat brain

In the present study, neuroinflammation was induced by bilateral intracerebroventricular (ICV) administration of Lipopolysaccharide (LPS). Proinflammatory cytokines (TNF-α and IL-1β), acetylcholinesterase (AChE) activity, malondialdehyde (MDA) and reduced glutathione (GSH) were studied as markers for neuroinflammation, cholinergic activity and oxidative stress respectively in different brain regions at different time points after LPS injection. LPS produced increase in proinflammatory cytokines, MDA and the decrease in level of GSH at 24 h indicating a state of inflammation in brain regions, which was significantly blocked by Ibuprofen, a non steroidal anti-inflammatory drug. Enhanced AChE activity with these inflammatory markers after LPS administration indicates a possible relationship between neuroinflammation and cholinergic system during the development of neurodegenerative diseases.

Effects of Short‐Term Exposure to Manganese on the Adult Rat Brain Antioxidant Status and the Activities of Acetylcholinesterase, (Na+,K+)‐ATPase and Mg2+‐ATPase: Modulation by l‐Cysteine

Manganese (Mn) is an essential metalloenzyme component that in high doses can exert serious oxidative and neurotoxic effects. The aim of this study was to investigate the potential effect of the antioxidant L-cysteine (Cys, 7 mg/kg) on the adult rat brain total antioxidant status (TAS) and the activities of acetylcholinesterase (AChE), Na+,K+-ATPase and Mg2+-ATPase induced by short-term Mn administration (as Mn chloride, 50 mg/kg). Twenty-eight male Wistar rats were divided into four groups: A (saline-treated control), B (Mn), C (Cys) and D (Mn and Cys). All rats were treated once daily, for 1 week with intraperitoneal injections of the tested compounds. Rats were killed by decapitation and mentioned parameters were measured spectrophotometrically. Rats treated with Mn exhibited a significant reduction in brain TAS (-39%, P < 0.001, B versus A) that was partially reversed by Cys co-administration (-13%, P < 0.01, D versus A), while Cys (group C) had no effect on TAS. The rat brain AChE activity was found significantly increased by both Mn (+21%, P < 0.001, B versus A) and Cys (+61%, P < 0.001, C versus A), while it was adjusted into the control levels by the co-administration of Mn and Cys. The activity of rat brain Na+,K+-ATPase was not affected by Mn administration, while Mg2+-ATPase exhibited a slight but statistically significant reduction in its activity (-9%, P < 0.01, B versus A) due to Mn, which was further reduced by Cys co-administration. The above findings suggest that short-term Mn in vivo administration causes a statistically significant decrease in the rat brain TAS and an increase in AChE activity. Both effects can be, partially or totally, reversed into the control levels by Cys co-administration (which could thus be considered for future applications as a neuroprotective agent against chronic exposure to Mn and the treatment of manganism). The activity of Na+,K+-ATPase is not affected by Mn, while Mg2+-ATPase activity is slightly (but significantly) inhibited by Mn, possibly due to Mg replacement.

P.1.c.041 Immediate and long term effects of perinatal phencyclidine treatment on the acetylcholinesterase activity in rat brain

P.1.c.041 Immediate and long term effects of perinatal phencyclidine treatment on the acetylcholinesterase activity in rat brain

The Evaluation of Altered Antioxidative Defense Mechanism and Acetylcholinesterase Activity in Rat Brain Exposed to Chlorpyrifos, Deltamethrin, and Their Combination

ABSTRACTThe present investigation was undertaken to examine the effects of chlorpyrifos (CP, an organophosphate) and deltamethrin (DM, a pyrethroid pesticide) treatments at low and high doses and their combination on lipid peroxidation and antioxidant enzyme activities such as SOD, GSH-Px, and CAT and also AChE activity in rat brain following 16 weeks of exposure. Antioxidative defense mechanisms and lipid peroxidation in rat brain tissues display different responses depending on different pesticide treatments and doses. Biochemical analysis showed that administration of chlorpyrifos and deltamethrin causes brain damage via production of MDA and inhibition of AChE. In the present study, we observed that LPO levels are higher at low doses than at high doses, but DM is more pronounced than CP in this increase. Observations show that SOD increases with the dose, CAT decreases at the higher dose, and GSH-Px again increases with the dose in both pesticide treatments, but especially in DM. Experimentally, oxidative–antioxidative balance is more affected by deltamethrin treatment than that of chlorpyrifos. The effects of combination of DM and CP on LPO may be due to functional, dispositional, or chemical antagonism, while the effect of the combination on CAT activity may be synergistic.

Ethidium bromide inhibits rat brain acetylcholinesterase activity in vitro

Ethidium bromide (EtBr), a fluorescent dark red compound and stain for double-stranded DNA and RNA was used to study acetylcholinesterase (AChE) activity in vitro together with kinetic parameters of this enzyme in the striatum (ST), hippocampus (HP), cerebral cortex (CC) and cerebellum (CB) of adult rats. AChE activity in vitro in the ST, HP, CC and CB was significantly reduced ( p < 0.05) in the presence of EtBr at concentrations of 0.00625, 0.0125, 0.025, 0.05 and 0.1 mM. For the analysis of the kinetic three concentrations of EtBr were tested (0.00625, 0.025 and 0.1 mM). An uncompetitive inhibition type was observed in the ST, HP and CC, whereas in the CB the inhibition type was mixed. These data indicate that EtBr should be considered a strong inhibitor of AChE activity demonstrating that there is an interaction between this compound and the cholinergic system.

Rat brain acetylcholinesterase activity: developmental profile and maturational sensitivity to carbamate and organophosphorus inhibitors

A growing body of evidence indicates that young animals exhibit an increased susceptibility to the lethal effects of cholinesterase (ChE)-inhibiting insecticides. Our laboratory is engaged in defining factors which may explain this age-related sensitivity. This report includes results from experiments designed to compare the developmental profiles, kinetic parameters and intrinsic (i.e. in vitro) sensitivity of developing male rat brain acetylcholinesterase (AChE) activity to carbamate and organophosphorus anticholinesterases. Total ChE activity in whole brain for each age was composed of about 90% AChE and 10% butyrylcholinesterase (BuChE) activity for the six ages examined. Brain AChE activity showed an age-related increase in V max until postnatal day 17 with no change in K m (average of all six ages ∼72 μM). Optimal substrate (acetylthiocholine) concentration for each age was 1 mM, and there was substantial (≈10%) substrate inhibition at 2.5 mM. IC 50s (the concentration of compound that inhibits 50% of the AChE activity in 30 min at 26°C) defined concomitantly for postnatal day 4 and adult brain AChE using either aldicarb, carbaryl, chlorpyrifos-oxon or malaoxon were virtually identical at both ages with average IC 50 values being: aldicarb=2.4 μM, carbaryl=1.7 μM, chlorpyrifos-oxon=4.9 nM and malaoxon=140 nM. In summary, AChE in young and adult brain differs mostly in specific activity while the K ms, substrate profiles, and in vitro sensitivity to selected anticholinesterase insecticides are not different. Therefore, these data support and extend the hypothesis that the greater sensitivity of the young animals to anticholinesterase pesticides is not due to the greater sensitivity of the target molecule AChE to these inhibitors.