Acetylcholinesterase Activities In Synaptosomes Research Articles

Changes in motor function and brain cortex mitochondrial active oxygen species production in aged mice.

Neuronal ageing is a complex physiological process, associated to metabolic and motor changes. In this study, 3 and 17 months old male Swiss mice were used. Aged mice exhibited a significant reduction in motor performance and walking footprint pattern. Synaptosomes and mitochondrial fractions were isolated from mouse brain cortex. Active oxygen species and cardiolipin content were measured in both subcellular fractions. Synaptosomal acetylcholinesterase activity was measured in both animal age groups. Results showed that superoxide levels were 42.9% lower in synaptosomes from old mice as compared with young animals, while no changes were observed in non-synaptic mitochondria. Succinate-glutamate dependent H2O2 production rate was 27.5% decreased in non-synaptic mitochondria from aged mice. Cardiolipin content was 21% decreased in synaptosomes from 17-months old animals, while no changes were observed in non-synaptic mitochondria. Acetylcholinesterase activity decreased 16% in 17-months old mice, as compared with young animals. Age-related alterations in neuronal function could be associated with changes in active oxygen species at synapses, with parallel motor deficiencies.

Free radical production and antioxidant status in brain cortex non-synaptic mitochondria and synaptosomes at alcohol hangover onset

Alcohol hangover (AH) is the pathophysiological state after a binge-like drinking. We have previously demonstrated that AH induced bioenergetics impairments in a total fresh mitochondrial fraction in brain cortex and cerebellum. The aim of this work was to determine free radical production and antioxidant systems in non-synaptic mitochondria and synaptosomes in control and hangover animals. Superoxide production was not modified in non-synaptic mitochondria while a 17.5% increase was observed in synaptosomes. A similar response was observed for cardiolipin content as no changes were evidenced in non-synaptic mitochondria while a 55% decrease in cardiolipin content was found in synaptosomes. Hydrogen peroxide production was 3-fold increased in non-synaptic mitochondria and 4-fold increased in synaptosomes. In the presence of deprenyl, synaptosomal H2O2 production was 67% decreased in the AH condition. Hydrogen peroxide generation was not affected by deprenyl addition in non-synaptic mitochondria from AH mice. MAO activity was 57% increased in non-synaptic mitochondria and 3-fold increased in synaptosomes. Catalase activity was 40% and 50% decreased in non-synaptic mitochondria and synaptosomes, respectively. Superoxide dismutase was 60% decreased in non-synaptic mitochondria and 80% increased in synaptosomal fractions. On the other hand, GSH (glutathione) content was 43% and 17% decreased in synaptosomes and cytosol. GSH-related enzymes were mostly affected in synaptosomes fractions by AH condition. Acetylcholinesterase activity in synaptosomes was 11% increased due to AH. The present work reveals that AH provokes an imbalance in the cellular redox homeostasis mainly affecting mitochondria present in synaptic terminals.

Dendropanax morbifera Léveille extract ameliorates cadmium-induced impairment in memory and hippocampal neurogenesis in rats

BackgroundCadmium leads to learning and memory impairment. Dendropanax morbifera Léveille stem extract (DMS) reduces cadmium-induced oxidative stress in the hippocampus. We investigated the effects of DMS on cadmium-induced impairments in memory in rats.MethodsCadmium (2 mg/kg), with or without DMS (100 mg/kg), was orally administered to 7-week-old Sprague-Dawley rats for 28 days. Galantamine (5 mg/kg), an acetylcholinesterase inhibitor, was intraperitoneally administered as a positive control. A novel-object recognition test was conducted 2 h after the final administration. Cell proliferation and neuroblast differentiation were assessed by immunohistochemistry for Ki67 and doublecortin, respectively. Acetylcholinesterase activity in the synaptosomes of the hippocampus was also measured based on the formation of 5,5′-dithio-bis-acid nitrobenzoic acid.ResultsAn increase in the preferential exploration time of new objects was observed in both vehicle-treated and cadmium-treated rats. In addition, DMS administration increased cell proliferation and neuroblast differentiation in the dentate gyrus of vehicle-treated and cadmium-treated rats. Acetylcholinesterase activity in the hippocampal synaptosomes was also significantly higher in the DMS-treated group than in the vehicle-treated group. The effect of DMS on cadmium-induced memory impairment and cell proliferation in the hippocampus was comparable to that of galantamine.ConclusionsThese results suggest that DMS ameliorates cadmium-induced memory impairment via increase in cell proliferation, neuroblast differentiation, and acetylcholinesterase activity in the hippocampus. The consumption of DMS may reduce cadmium-induced neurotoxicity in animals or humans.

Effect of dietary supplementation of ginger and turmeric rhizomes on ectonucleotidases, adenosine deaminase and acetylcholinesterase activities in synaptosomes from the cerebral cortex of hypertensive rats

Ginger and turmeric rhizomes are used in folk medicine for the treatment of several cerebrovascular diseases with limited scientific basis for their action. Hence, in this study, we investigate the effects of two Zingiberaceae varieties (ginger and turmeric) on ectonucleotidases (NTPDase and 5′-nucleotidase), adenosine deaminase (ADA) and acetylcholinesterase (AChE) activities in synaptosomes of cerebral cortex from l-NAME induced hypertensive rats. The animals were divided into seven groups (n=10): normotensive control rats; hypertensive rats; hypertensive rats treated with atenolol; normotensive and hypertensive rats treated with 4% supplementation of turmeric and ginger rhizomes, respectively. After 14 days of pre-treatment with both rhizomes the animals were induced with hypertension by oral administration of l-NAME. The results revealed an increase of ATP and AMP hydrolysis as well as ADA and AChE activities of cerebral cortex synaptosomes in induced rats when compared with the control. The supplementation of both rhizomes prevented these alterations by decreasing ATP and AMP hydrolysis and ADA and AChE activities in cerebral cortex. In conclusion, this study demonstrated that both rhizomes interfere with the purinergic and cholinergic neurotransmission in cerebral cortex of hypertensive rats. Therefore, we can suggest that both rhizomes exert neuroprotective potential under hypertensive state.

Synaptosomal acetylcholinesterase activity variation pattern in the presence of electromagnetic fields

Acetylcholinesterase (AChE) is the enzyme that controls the acetylcholine (ACh) concentrations in cholinergic synaptic clefts by hydrolyzing ACh to choline and acetate. Cholinergic synapses are involved in important functions such as learning, memory and cognition. In this study, we investigated the effects of a wide range of extremely low frequency electromagnetic fields (ELF-EMFs) on synaptic ACh concentrations through AChE enzyme activity assay. Synaptosome suspensions were prepared as a neural terminus from cerebral cortex of sheep brain. Prepared synaptosomes were exposed to ELF-EMFs with frequency ranging from 50Hz to 230Hz for duration between 15 and 120min and flux intensity between 0.1mT and 1.7mT. Consequently, AChE activity was measured by Ellman method. Raw data were analyzed by neural network based software, Inform 4.02, to predict AChE activity pattern through nine 3D curves. These curves showed that AChE activity decreases when exposed to ELF-EMFs of 1.2mT to 1.7mT intensity and 50Hz to 90Hz frequency. Thus, it is proposed that exposure to fields of in this range of frequency–intensity would be effective in clinical treatments of cholinergic disorders to increase synaptic ACh concentration. However, more in vivo experiments are needed to develop this suggested treatment.

The effect of curcumin in the ectonucleotidases and acetylcholinesterase activities in synaptosomes from the cerebral cortex of cigarette smoke-exposed rats

With the evidence that curcumin may be a potent neuroprotective agent and that cigarette smoke is associated with a decline in the cognitive performance as our bases, we investigated the activities of Ecto-Nucleoside Triphosphate Diphosphohydrolase (NTPDase), 5'-nucleotidase and acetylcholinesterase (AChE) in cerebral cortex synaptosomes from cigarette smoke-exposed rats treated with curcumin (Cur). The experimental procedures entailed two sets of experiments. In the first set, the groups were vehicle, Cur 12·5, 25 and 50 mg·kg(-1) ; those in the second set were vehicle, smoke, smoke and Cur 12·5, 25 and 50 mg·kg(-1) . Curcumin prevented the increased NTPDase, 5'-nucleotidase and AChE activities caused by smoke exposure. We suggest that treatment with Cur was protective because the decrease of ATP and acetylcholine (ACh) concentrations is responsible for cognitive impairment, and both ATP and ACh have key roles in neurotransmission.

Ectonucleotidase and acetylcholinesterase activities in synaptosomes from the cerebral cortex of streptozotocin-induced diabetic rats and treated with resveratrol

The aim of the present study was to investigate the effects of resveratrol (RV), an important neuroprotective compound on NTPDase, 5′-nucleotidase and acetylcholinesterase (AChE) activities in cerebral cortex synaptosomes of streptozotocin (STZ)-induced diabetic rats. The animals were divided into six groups ( n = 8): control/saline; control/RV 10 mg/kg; control/RV 20 mg/kg; diabetic/saline; diabetic/RV 10 mg/kg; diabetic/RV 20 mg/kg. After 30 days of treatment with resveratrol the animals were sacrificed and the cerebral cortex was removed for synaptosomes preparation and enzymatic assays. The results demonstrated that NTPDase and 5′-nucleotidase activities were significantly increased in the diabetic/saline group ( p < 0.05) compared to control/saline group. Treatment with resveratrol significantly increased NTPDase, 5′-nucleotidase activities in the diabetic/RV10 and diabetic/RV20 groups ( p < 0.05) compared to diabetic/saline group. When resveratrol was administered per se there was also an increase in the activities of these enzymes in the control/RV10 and control/RV20 groups ( p < 0.05) compared to control/saline group. AChE activity was significantly increased in the diabetic/saline group ( p < 0.05) compared to control/saline group. The treatment with resveratrol prevented this increase in the diabetic/RV10 and diabetic/RV20 groups. In conclusion, this study demonstrated that the resveratrol interfere with the purinergic and cholinergic neurotransmission by altering NTPDase, 5′-nucleotidase and AChE activities in cerebral cortex synaptosomes of diabetic rats. In this context, we can suggest that resveratrol should be considered potential therapeutics and scientific tools to be investigated in brain disorders associated with the diabetes.

Effect of Long-Term Exposure to Aluminum on the Acetylcholinesterase Activity in the Central Nervous System and Erythrocytes

Aluminum (Al), a neurotoxic agent, has been associated with Alzheimer's disease (AD), which is characterized by cholinergic dysfunction in the central nervous system. In this study, we evaluated the effect of long-term exposure to aluminum on acetylcholinesterase (AChE) activity in the central nervous system in different brain regions, in synaptosomes of the cerebral cortex and in erythrocytes. The animals were loaded by gavage with AlCl(3) 50 mg/kg/day, 5 days per week, totalizing 60 administrations. Rats were divided into four groups: (1) control (C); (2) 50 mg/kg of citrate solution (Ci); (3) 50 mg/kg of Al plus citrate (Al + Ci), and (4) 50 mg/kg of Al (Al). AChE activity in striatum was increased by 15% for Ci, 19% for Al + Ci and 30% for Al, when compared to control (P < 0.05). The activity in hypothalamus increased 23% for Ci, 26% for Al + Ci and 28% for Al, when compared to control (P < 0.05). AChE activity in cerebellum, hippocampus and cerebral cortex was decreased by 11%, 23% and 21% respectively, for Al, when compared to the respective controls (P < 0.05). AChE activity in synaptosomes was increased by 14% for Al, when compared to control (P < 0.05). Erythrocyte AChE activity was increased by 17% for Al + Ci and 11% for Al, when compared to control (P < 0.05). These results indicate that Al affects at the same way AChE activity in the central nervous system and erythrocyte. AChE activity in erythrocytes may be considered a marker of easy access of the central cholinergic status.

Effects In Vitro of Guanidinoacetate on Adenine Nucleotide Hydrolysis and Acetylcholinesterase Activity in Tissues from Adult Rats

Guanidinoacetate methyltransferase (GAMT) deficiency is a disorder of creatine metabolism characterized by low plasma creatine concentrations in combination with elevated guanidinoacetate (GAA) concentrations. The aim of this work was to investigate the in vitro effect of guanidinoacetate in NTPDase, 5'-nucleotidase and acetylcholinesterase activities in the synaptosomes, platelets and blood of rats. The results showed that in synaptosomes the NTPDase and 5'-nucleotidase activities were inhibited significantly in the presence of GAA at concentrations of 50, 100, 150 and 200 microM (P < 0.05). However, in platelets GAA at the same concentrations caused a significant increase in the activities of these two enzymes (P < 0.05). In relation to the acetylcholinesterase activity, GAA caused a significant inhibition in the activity of this enzyme in blood at concentrations of 150 and 200 microM (P < 0.05), but did not alter the acetylcholinesterase activity in synaptosomes from the cerebral cortex. Our results suggest that alterations caused by GAA in the activities of these enzymes may contribute to the understanding of the neurological dysfunction of GAMT-deficient patients.

Influence of dietary fat on the activities of subcellular membrane-bound enzymes from different regions of rat brain

The effect of different dietary fats with varying degrees of unsaturation and essential fatty acid composition, which are commonly consumed in India, on the activity of some important membrane-bound enzymes was assessed in different brain regions of rat. Four groups of male CFY weanling rats were fed nutritionally adequate diets containing groundnut, coconut, safflower or mustard oil as fat source at 20% level for 16 weeks. The synaptosomal, microsomal and myelin membranes were prepared from three brain regions, viz., cerebrum, cerebellum and brain stem from each group. The activities of Na +, K +-ATPase, Mg 2+-ATPase and acetylcholinesterase were assayed and the fatty acid composition was determined in these subcellular membrane fractions. The safflower oil-fed group showed higher Na +, K +-ATPase activity in most membrane fractions.than the coconut or mustard oil-fed groups. The Mg 2+-ATPase activity was found to be similar amongst all groups in all the brain regions. The synaptosomal acetylcholinesterase activity was distinctly higher in coconut and groundnut oil-fed groups when compared to safflower or mustard oil consuming groups. Alterations in the activities of these subcellular membrane-bound enzymes are expected to exert a significant impact on the electrophysiological and metabolic functions of brain. Results of the present study show that depending on the nature of dietary fat the fatty acid composition of subcellular membranes is altered, which in turn could regulate the activity of membrane-bound enzymes that are vital for brain function.

Higher environmental temperature-induced change in synaptosomal acetylcholinesterase activity of brain regions

Exposure of adult male albino rats to higher environmental temperature (HET) at 35 degrees for 2-12 hr or at 45 degrees for 1-2 hr increases hypothalamic synaptosomal acetylcholinesterase (AChE) activity. Synaptosomal AChE activity in cerebral cortex of rats exposed to 35 degrees for 12 hr and in cerebral cortex and pons-medulla of rats exposed to 45 degrees for 1-2 hr are also activated. AChE activity of synaptosomes prepared from normal rat brain regions incubated in-vitro at 39 degrees or 41 degrees for 0.5 hr increases significantly in cerebral cortex and hypothalamus. The activation of AChE in pons-medulla is also observed when this brain region is incubated at 41 degrees for 0.5 hr. Increase of (a) the duration of incubation at 41 degrees and (b) the incubation temperature to 43 degrees under in-vitro condition decreases the synaptosomal AChE activity. Lineweaver-Burk plots indicate that (a) in-vivo and in-vitro HET-induced increases of brain regional synaptosomal AChE activity are coupled with an increase of Vmax without any change in Km (b) very high temperature (43 degrees under in-vitro condition) causes a decrease in Vmax with an increase in Km of AChE activity irrespective of brain regions. Arrhenius plots show that there is a decrease in transition temperature in hypothalamus of rats exposed to either 35 degrees or 45 degrees; whereas such a decrease in transition temperature of the pons-medulla and cerebral cortex regions are observed only after exposure to 45 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)

Carbaryl-induced elevation of corticosterone level and cholinergic mechanism.

Administration of a single dose (200 mg/kg, p.o.) of carbaryl to rats produced a significant rise in adrenal and plasma corticosterone levels and an increase of tyrosine alpha-ketoglutarate transaminase activity in the liver cytosol. Synaptosomal acetylcholinesterase activity of the hypothalamic and the striatal regions of rat brain was decreased by carbaryl treatment under similar conditions. Pretreatment (0.5 h) with atropine sulphate (10 mg/kg, i.p.) failed to counteract the carbaryl-induced elevation of adrenal and plasma corticosterone levels and hence the liver tyrosine alpha-ketoglutarate transaminase activity. Present results suggest that the carbaryl-induced rise in the corticosterone level in the adrenal gland and plasma is not due to a cholinergic mechanism.

Effect of dietary lipid on synaptosomal acetylcholinesterase activity.

The effect of dietary lipid on the thermotropic properties of acetylcholinesterase activity was examined in rat synaptosomal membrane preparations after feeding diets containing soya-bean oil, sunflower oil or soya-bean phosphatidylcholine as the dietary fats. Arrhenius plots and energies of activation were altered by the duration of feeding as a function of time, as well as by the composition of diet fat fed. Animals fed sunflower oil had the highest maximal velocity for acetylcholinesterase activity. The observations of this study suggest that dietary fat is an important determinant of the physicokinetic properties of lipid-dependent functions in brain synaptosomal membranes.

Rat brain acetylcholinesterase and its isoenzymes after intracerebral administration of DFP

Acetylcholinesterase (AChE) activity was followed in the synaptosomal and microsomal fractions of rat brains after intracerebral administration of diisopropyl phosphofluoridate (DFP). Fifteen days after DFP administration to 20-day-old rats, 47 and 41 per cent of the inhibited (phosphorylated) AChE activity was replaced in the synaptosomes and microsomes respectively. After correcting these values for ontogenic development of AChE in the young rats, post-DFP increase of AChE activity amounted to 16 and 43 per cent of controls in the microsomal and synaptosomal fractions respectively. In 58-day-old rats, 45 and 64 per cent, respectively, of the inhibited microsomal and synaptosomal AChE activity was replaced within 20 days after the administration of DFP; in the control 58-day-old rats the increase in AChE activity during the 20-day period was minimal. Both the microsomal and synaptosomal fractions showed four AChE isoenzymes. The two sets of isoenzymes differed in their DFP sensitivity and in the rate of the post-DFP return of activity; after DFP, each fraction reconstituted its characteristic quantitative isoenzyme pattern. Altogether, the early and fast post-DFP appearance of AChE activity in the synaptosomal fraction and the early reconstitution of the synaptosomal isoenzyme pattern suggest that nerve endings are capable of AChE synthesis or repair apart from the similar microsomal process.