Vera Maria Morsch

Resveratrol prevents memory deficits and the increase in acetylcholinesterase activity in streptozotocin-induced diabetic rats

The objective of the present study was to investigate the effect of the administration of resveratrol (RV) on memory and on acetylcholinesterase (AChE) activity in the cerebral cortex, hippocampus, striatum, hypothalamus, cerebellum and blood in streptozotocin-induced diabetic rats. The animals were divided into six groups (n=6-13): Control/saline; Control/RV 10 mg/kg; Control/RV 20 mg/kg; Diabetic/saline; Diabetic/RV 10 mg/kg; Diabetic/RV 20 mg/kg. One day after 30 days of treatment with resveratrol the animals were submitted to behavioral tests and then submitted to euthanasia and the brain structures and blood were collected. The results showed a decrease in step-down latency in diabetic/saline group. Resveratrol (10 and 20 mg/kg) prevented the impairment of memory induced by diabetes. In the open field test, no significant differences were observed between the groups. In relation to AChE activity, a significant increase in diabetic/saline group (P<0.05) was observed in all brain structures compared to control/saline group. However, AChE activity decreased significantly in control/RV10 and control/RV20 (P<0.05) groups in cerebral cortex, hippocampus and striatum, while no significant differences were observed in diabetic/RV10 and diabetic/RV20 groups in all brain structures compared to control/saline group. Blood AChE activity increased significantly in diabetic/saline group (P<0.05) decreased in control/RV10, control/RV20 and diabetic/RV20 groups (P<0.05) compared to control/saline group. In conclusion, the present findings showed that treatment with resveratrol prevents the increase in AChE activity and consequently memory impairment in diabetic rats, demonstrating that this compound can modulate cholinergic neurotransmission and consequently improve cognition.

N-acetylcysteine prevents memory deficits, the decrease in acetylcholinesterase activity and oxidative stress in rats exposed to cadmium

The present study investigated the effect of the administration of N-acetylcysteine (NAC), on memory, on acetylcholinesterase (AChE) activity and on lipid peroxidation in different brain structures in cadmium (Cd)-exposed rats. The rats received Cd (2 mg/kg) and NAC (150 mg/kg) by gavage every other day for 30 days. The animals were divided into four groups (n=12-13): control/saline, NAC, Cd, and Cd/NAC. The results showed a decrease in step-down latency in the Cd-group, but NAC reversed the impairment of memory induced by Cd intoxication. Rats exposed to Cd and/or treated with NAC did not demonstrate altered shock sensitivity. Decreased AChE activity was found in hippocampus, cerebellum and hypothalamus in the Cd-group but NAC reversed this effect totally or partially while in cortex synaptosomes and striatum there was no alteration in AChE activity. An increase in TBARS levels was found in hippocampus, cerebellum and hypothalamus in the Cd-group and NAC abolished this effect while in striatum there was no alteration in TBARS levels. Urea and creatinine levels were increased in serum of Cd-intoxicated rats, but NAC was able to abolish these undesirable effects. The present findings show that treatment with NAC prevented the Cd-mediated decrease in AChE activity, as well as oxidative stress and consequent memory impairment in Cd-exposed rats, demonstrating that this compound may modulate cholinergic neurotransmission and consequently improve cognition. However, it is necessary to note that the mild renal failure may be a contributor to the behavioral impairment found in this investigation.

Measurement of oxidative stress and antioxidant status in acute lymphoblastic leukemia patients

OBJECTIVES To evaluate the oxidative status and antioxidant defense in patients with acute lymphoblastic leukemia (ALL). DESIGN AND METHODS We measured concentrations of plasmatic thiobarbituric acid reactive substances (TBARS), serum protein carbonylation, whole blood catalase (CAT) and superoxide dismutase (SOD) activities, as well as the plasmatic and erythrocyte thiol levels and serum vitamin E concentration. This study was performed on 80 children with ALL divided into 4 groups: just diagnosed, remission induction, remission maintenance and out-of-treatment. RESULTS TBARS levels and serum protein carbonylation were higher in ALL patients than in controls and reduced levels of antioxidants were found in these patients. CONCLUSION These findings may indicate a possible link between decreased antioxidants and increased levels of cells alterations due to oxidative damage, supporting the idea that there is a persistence of oxidative stress in acute lymphoblastic leukemia.

New Benzodiazepines Alter Acetylcholinesterase and ATPDase Activities

This study examines the effect of new 1,5 benzodiazepines on acetylcholinesterase (AChE) and ATPDase (apyrase) activities from cerebral cortex of adult rats. Simultaneously, the effects of the classical 1,4-benzodiazepine on these enzymes were also studied for comparative purpose. The compounds 2-trichloromethyl-4-phenyl-3H-1,5-benzodiazepin and 2-trichloromethyl-4-(p-methyl-phenyl)-3H-1,5-benzodiazepin significantly inhibited acetylcholinesterase activity (p < 0.01) when tested in the range of 0.18–0.35 mM. The inhibition caused by these two new benzodiazepines was noncompetitive in nature. Similarly, at concentrations ranging from 0.063 to 0.25 mM, the 1,5 benzodiazepines inhibited ATP and ADP hydrolysis by synaptosomes from cerebral cortex (p < 0.01). However, the inhibition of nucleotide hydrolysis was uncompetitive in nature. Our results suggest that, although diazepam and the new benzodiazepines have chemical differences, they both presented an inhibitory effect on acetylcholinesterase and ATPDase activities.

Cadmium toxicity causes oxidative stress and induces response of the antioxidant system in cucumber seedlings

In this study, the effects of cadmium (Cd) on lipid peroxidation, electrolyte leakage, protein oxidation, ascorbate peroxidase (APX; E.C. 1.11.1.11), catalase (CAT; E.C. 1.11.1.6) and superoxide dismutase (SOD; E.C. 1.15.1.1) activities, and ascorbic acid, non-protein thiol groups and total soluble protein contents in cucumber seedlings (Cucumis sativus L.) were investigated. Seedlings were grown in vitro in an agar-solidified substrate containing four Cd levels as CdCl2 (0, 100, 400, and 1000 µmol L-1) for 10 d. The lowest Cd level decreased the malondialdehyde concentration. Electrolyte leakage increased only at 1000 µmol Cd L-1, whereas protein oxidation and total soluble protein content were enhanced at 400 and 1000 µmol Cd L-1. Activity of APX was inhibited while the activities of CAT and SOD were increased at all Cd concentrations. Ascorbic acid was enhanced at 400 and 1000 µmol Cd L-1 whereas non-protein thiol groups were increased at all Cd supplies. The results evidence the importance of the enzymatic and non-enzymatic antioxidant system in response to cadmium toxicity in cucumber seedlings.

Antidepressants inhibit human acetylcholinesterase and butyrylcholinesterase activity

This study examines the effect of the antidepressants fluoxetine, sertraline and amitriptyline on cholinesterase (acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE)) activities in human serum and erythrocyte membrane (ghost). The concentrations used range from 3 to 60 microM for fluoxetine and amitriptyline and 0.3 to 12 microM for sertraline. At the micromolar range concentration, different classes of antidepressants, including fluoxetine and sertraline (selective serotonin reuptake inhibitors (SSRIs)) and amitriptyline (tricyclic antidepressant) inhibited human serum cholinesterase. The order of inhibitory potency was sertraline>amitriptyline>>fluoxetine and the IC(50) values were 4.05, 9.43 and 62 microM, respectively. Analysis of kinetic data indicated that the inhibition caused by all the antidepressants was mixed in nature. At the micromolar range concentration, sertraline (60-120 microM) and amitriptyline (60-180 microM) inhibited human erythrocyte AChE. The order of inhibitory potency was sertraline>amitriptyline and the IC(50) values were 80 and 134 microM, respectively. Analysis of kinetic data indicated that the inhibition caused by all the antidepressants in AChE human erythrocyte membrane (ghost) was mixed in nature. The interaction of sertraline with the cholinesterase is labile since the removal of inhibitor by gel filtration recovered completely the enzyme activity. Our results demonstrate that the usual clinical antidepressants are inhibitors of the cholinesterases on human serum and erythrocyte membrane.

Oxidative stress versus antioxidant defenses in patients with acute myocardial infarction

Acute myocardial infarction (AMI) is a highly dynamic event, which is associated with increasing production of reactive oxygen species (ROS). The imbalance between ROS production and antioxidant defenses leads to the condition known as oxidative stress. The most widely recognized effect of increasing oxidative stress is the oxidation and damage of macromolecules, membranes, proteins, and DNA. Therefore, in this study we sought to evaluate oxidative stress and antioxidant defenses in patients with AMI. Lipid peroxidation, protein carbonyl levels, and enzymatic and nonenzymatic antioxidants were assessed in samples obtained from 40 AMI patients and 40 control patients. AMI was characterized by clinical, electrocardiographic, and laboratory criteria. The control group was divided into two groups of 20 patients: a control group with healthy patients and a risk group. Our results demonstrated an increase in substances reactive to thiobarbituric acid (TBARS) and carbonyl protein levels in the AMI and risk groups. In addition, a positive correlation was found between TBARS, carbonyl protein levels, and troponin I in AMI patients. Surprisingly, for the enzymatic antioxidant defenses, catalase and superoxide dismutase, we observed an increase in these parameters in the AMI and risk groups when compared with healthy patients. However, a decrease in nonenzymatic antioxidants such as vitamin C and vitamin E was observed in AMI patients when compared with the healthy group and the risk group. The increase in oxidative stress was probably a result of the elevation in ROS production due to the ischemic/reperfusion event that occurs in AMI, in addition to the decrease of nonenzymatic antioxidant defenses.

ATP and ADP hydrolysis in fish, chicken and rat synaptosomes

Ecto-enzymes capable of hydrolyzing ATP and ADP (NTPDase) are present in the central nervous system of various species. In the present investigation we studied the synaptosomal NTPDase (ATP diphosphohydrolase, apyrase, E.C. 3.6.1.5) from fish, chicken and rats under different conditions and in the presence of several classical inhibitors. The cation concentration required for maximal activity was 0.5 mM for fish, 1.0 mM for chickens and 1.5 mM for rats with both substrates. The results showed that the pH optimum for all animal preparations was close to 8.0. The temperature used was 25-27 degrees C for fish and 35-37 degrees C for chicken and rat preparations. The inhibitors azide and fluoride only inhibited the preparation at high concentrations (10 mM). Lanthanum (0.1-0.4 mM), N-ethylmaleimide (0.4-3.0 mM) and ouabain (0.5-3.0 mM) had no effect on NTPDase activity from fish, chickens or rats. Orthovanadate (0.1-0.3 mM) only inhibited fish synaptosomal NTPDase. Trifluoperazine (0.05-0.2 mM) and suramin (0.03-0.3 mM) inhibited NTPDase at all concentrations tested. Suramin was the most potent compound in causing inhibition, presenting inhibition at 30 microM. Our results demonstrate that the synaptosomal NTPDase response to several factors is similar in fish, chickens and rats, and that the enzyme presents functional homology.

Enzymes that hydrolyze adenine nucleotides of patients with hypercholesterolemia and inflammatory processes

The activity of NTPDase (EC 3.6.1.5, apyrase, CD39) was verified in platelets from patients with increasing cholesterol levels. A possible association between cholesterol levels and inflammatory markers, such as oxidized low‐density lipoprotein, highly sensitive C‐reactive protein and oxidized low‐density lipoprotein autoantibodies, was also investigated. Lipid peroxidation was estimated by measurement of thiobarbituric acid reactive substances in serum. The following groups were studied: group I, < 150 mg·dL−1 cholesterol; group II, 151–200 mg·dL−1 cholesterol; group III, 201–250 mg·dL−1 cholesterol; and group IV, > 251 mg·dL−1 cholesterol. The results demonstrated that both ATP hydrolysis and ADP hydrolysis were enhanced as a function of cholesterol level. Low‐density lipoprotein levels increased concomitantly with total cholesterol levels. Triglyceride levels were increased in the groups with total cholesterol above 251 mg·dL−1. Oxidized low‐density lipoprotein levels were elevated in groups II, III, and IV. Highly sensitive C‐reactive protein was elevated in the group with cholesterol levels higher than 251 mg·dL−1. Oxidized low‐density lipoprotein autoantibodies were elevated in groups III and IV. Thiobarbituric acid reactive substance content was enhanced as a function of cholesterol level. In summary, hypercholesterolemia is associated with enhancement of inflammatory response, oxidative stress, and ATP and ADP hydrolysis. The increased ATP and ADP hydrolysis in group IV was confirmed by an increase in CD39 expression on its surface. The increase in CD39 activity is possibly related to a compensatory response to the inflammatory and pro‐oxidative state associated with hypercholesterolemia.

Effect of aluminum on δ-aminolevulinic acid dehydratase from mouse blood

Abstract The objective of this study was to investigate aluminum deposition in whole blood and plasma of mice and the activity of blood δ-aminolevulinic acid dehydratase (ALA-D) after in vitro and in vivo exposure to this element. In vitro experiments showed activation and inhibition of the enzyme activity when 0.01–5.0 mM of aluminum sulphate were used (IC50: 1.31 mM). Treatment with citrate and aluminum plus citrate increased ALA-D activity in vivo and the increase in enzyme activity was parallel to the increase in aluminum content in blood and plasma. These results show that aluminum has a distinct effect on ALA-D activity: first, at relatively lower concentrations it activated, and at high concentration it inhibited, blood ALA-D in vitro; second, it activated the enzyme when administered to drinking water. One important toxicological finding of the present report is that the apparent irrelevant addition of citrate to the drinking water significantly increased the level of aluminum in blood and plasma. Thus, in order to predict more accurately the extent of human exposure to aluminum it would be advantageous to consider the level of citrate ingestion and not exclusively the aluminum level in water or food.