Acetylcholinesterase activity in regions of mouse brain following acute and chronic treatment with a benzodiazepine inverse agonist

Evaluation of neurotoxicity and hepatotoxicity effects of acute and sub-acute oral administration of unripe ackee (Blighia sapida) fruit extract

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Acute oral dose of 2000 mg/kg of unripe B. sapida fruit extract (BSE) was toxic to mice.

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Repeated treatment with BSE impaired locomotor function, memory performance and shortened seizure latency in mice.

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Repeated treatment with BSE significantly up-regulate acetylcholinesterase enzyme activity in mice.

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Repeated treatment with BSE elevates oxidative stress in the brain and liver of mice.

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Repeated treatment with BSE showed histopathological evidences of toxicity in mice brain and liver.

Ackee (Blighia sapida) is a commonly eaten fruit that is indigenous to West Africa and Jamaica. Ackee poisoning in young children have been reported in parts of Nigeria due to consumption of the unripe fruits. This study was designed to identify potential mechanisms of acute and sub-acute toxicity of unripe B. sapida fruit extract (BSE).

Acute toxic effect was investigated in mice of either sex administered BSE 2000 mg/kg. The sub-acute toxicity effects were investigated in mice of either sex that received 28 days repeated administration of BSE (100 and 500 mg/kg, p.o.). Locomotor activity and memory performance were measured as well as seizure vulnerability in PTZ-induced model. Liver enzymes were assessed in the serum. Acetylcholinesterase, oxidative stress parameters and histopathological changes were assessed in the brain and liver tissues.

Signs and symptoms of toxicity such as urination, tremor, depressed locomotion and death were observed in acute toxicity test. Sub-acute dosing caused significant impairment in locomotor activity and memory performance in mice. Seizure threshold was shortened in BSE-treated compared to control mice. Brain acetylcholinesterase activity was significantly increased. Alkaline phosphatase (ALP) was significantly elevated in mice that received BSE (500 mg/kg). Furthermore, BSE caused significant increase in oxidative stress expressed in nitrite, malondialdehyde, reduced glutathione and catalase in the brain and liver tissues. Histological staining revealed neuronal damage of brain hippocampus and hepatocellular swelling and necrosis.

Blighia sapida unripe fruit extract increased susceptibility to seizure and impaired locomotor and memory function. The biochemical and histopathological findings revealed potential toxicity mechanisms related to neurotoxicity and hepatotoxicity.

Effect of agomelatine on memory deficits and hippocampal gene expression induced by chronic social defeat stress in mice

Chronic stress is known to induce not only anxiety and depressive-like phenotypes in mice but also cognitive impairments, for which the action of classical antidepressant compounds remains unsatisfactory. In this context, we investigated the effects of chronic social defeat stress (CSDS) on anxiety-, social- and cognitive-related behaviors, as well as hippocampal Bdnf, synaptic plasticity markers (PSD-95, Synaptophysin, Spinophilin, Synapsin I and MAP-2), and epigenetic modifying enzymes (MYST2, HDAC2, HDAC6, MLL3, KDM5B, DNMT3B, GADD45B) gene expression in C57BL/6J mice. CSDS for 10 days provoked long-lasting anxious-like phenotype in the open field and episodic memory deficits in the novel object recognition test. While total Bdnf mRNA level was unchanged, Bdnf exon IV, MAP-2, HDAC2, HDAC6 and MLL3 gene expression was significantly decreased in the CSDS mouse hippocampus. In CSDS mice treated 3 weeks with 50 mg/kg/d agomelatine, an antidepressant with melatonergic receptor agonist and 5-HT_2C receptor antagonist properties, the anxious-like phenotype was not reversed, but the treatment successfully prevented the cognitive impairments and hippocampal gene expression modifications. Altogether, these data evidenced that, in mice, agomelatine was effective in alleviating stress-induced altered cognitive functions, possibly through a mechanism involving BDNF signaling, synaptic plasticity and epigenetic remodeling.

Effect of canagliflozin and metformin on cortical neurotransmitters in a diabetic rat model

BACKGROUND

The rapid economic development in the Arabian Gulf has resulted in lifestyle changes that have increased the prevalence of obesity and type 2 diabetes, with the greatest increases observed in Kuwait. Dyslipidemia and diabetes are risk factors for disruptions in cortical neurotransmitter homeostasis. This study investigated the effect of the antidiabetic medications canagliflozin (CAN) and metformin (MET) on the levels of cortical neurotransmitters in a diabetic rat model.

MATERIALS AND METHODS

The rats were assigned to the control (C) group, the diabetic group that did not receive treatment (D) or the diabetic group treated with either CAN (10 mg/kg) or MET (100 mg/kg) for 2 or 4 weeks. Blood and urine glucose levels and cortical acetylcholinesterase (AChE) activity were assayed, and amino acid and monoamine levels were measured using HPLC.

RESULTS

The diabetic group exhibited a significant increase in AChE activity and a decrease in monoamine and amino acid neurotransmitter levels. In the CAN group, AChE was significantly lower than that in the D and D + MET groups after 2 weeks of treatment. In addition, a significant increase in some cortical monoamines and amino acids was observed in the D + MET and D + CAN groups compared with the D group. Histopathological analysis revealed the presence of severe focal hemorrhage, neuronal degeneration, and cerebral blood vessel congestion, with gliosis in the cerebrum of rats in the D group. The CAN-treated group exhibited severe cerebral blood vessel congestion after 2 weeks of treatment and focal gliosis in the cerebrum after 4 weeks of treatment. Focal gliosis in the cerebrum of rats in the MET-treated group was observed after 2 and 4 weeks of treatment.

CONCLUSIONS

We conclude that the effect of CAN and MET on neurotransmitters is potentially mediated by their antihyperglycemic and antihyperlipidemic effects. In addition, the effects of CAN on neurotransmitters might be associated with its receptor activity, and the effect of MET on neurotransmitters might be associated with cerebral metabolism.

Brain regional heterogeneity and toxicological mechanisms of organophosphates and carbamates

The brain is a well-organized, yet highly complex, organ in the mammalian system. Most investigators use the whole brain, instead of a selected brain region(s), for biochemical analytes as toxicological endpoints. As a result, the obtained data is often of limited value, since their significance is compromised due to a reduced effect, and the investigators often arrive at an erroneous conclusion(s). By now, a plethora of knowledge reveals the brain regional variability for various biochemical/neurochemical determinants. This review describes the importance of brain regional heterogeneity in relation to cholinergic and noncholinergic determinants with particular reference to organophosphate (OP) and carbamate pesticides and OP nerve agents.

Effects of Takju intake and moderate exercise training on brain acetylcholinesterase activity and learning ability in rats

Takju is a Korean alcoholic beverage made from rice, and is brewed with the yeast Saccharomyces cerevisiae. This study was conducted to evaluate the effects of exercise training and moderate Takju consumption on learning ability in 6-week old Sprague-Dawley male rats. The rats were treated with exercise and alcohol for 4 weeks in six separate groups as follows: non-exercised control (CC), exercised control (EC), non-exercised consuming ethanol (CA), exercised consuming ethanol (EA), non-exercised consuming Takju (CT), and exercised consuming Takju (ET). An AIN-93M diet was provided ad libitum. Exercise training was performed at a speed of 10 m/min for 15 minutes per day. Ethanol and Takju were administered daily for 6-7 hours to achieve an intake of about 10 ml after 12 hours of deprivation, and, thereafter, the animals were allowed free access to deionized water. A Y-shaped water maze was used from the third week to understand the effects of exercise and alcohol consumption on learning and memory. After sacrifice, brain acetylcholinesterase (AChE) activity was analyzed. Total caloric intake and body weight changes during the experiment were not significantly different among the groups. AChE activity was not significantly different among the groups. The number of errors for position reversal training in the maze was significantly smaller in the EA group than that in the CA and ET groups, and latency times were shorter in the EA group than those in the CC, EC, CT, and ET groups. The latency difference from the first to the fifth day was shortest in the ET group. The exercised groups showed more errors and latency than those of the non-exercised groups on the first day, but the data became equivalent from the second day. The results indicate that moderate exercise can increase memory and learning and that the combination of exercise and Takju ingestion may enhance learning ability.

In vitro effect of central nervous system active drugs on the ATPase-ADPase activity and acetylcholinesterase activity from cerebral cortex of adult rats

1. The effect of several central nervous system active drugs was studied in vitro on ATPase-ADPase activity and acetylcholinesterase (AChE) activity from the cerebral cortex of adult rats. 2. Lithium (1.0-10.0 mM) had no effect on either ATPase-ADPase or acetylcholinesterase activity. 3. Imipramine (0.5-5.0 mM), desipramine (0.5-5.0 mM), amitriptyline (0.1-1.0 mM) and diazepam (0.5-2.0 mM) inhibited ATP and ADP hydrolysis at all concentrations tested. 4. AChE activity was altered by imipramine (1.0-2.0 mM) and by diazepam (0.5-2.0 mM). 5. The possible participation of ATP diphosphohydrolase and AChE in the action of these drugs cannot be ruled out. The probable reduction of ATP, ADP and acetylcholine hydrolysis by the inhibitory effect of these drugs is discussed.

Effect of exercise training and chronic ethanol ingestion on cholinesterase activity and lipid peroxidation in blood and brain regions of rat

1. This study examines the effects of exercise training and chronic ethanol consumption on cholinesterase activity and its relationship to lipid peroxidation in blood and brain regions of rat. 2. Exercise training (6.5 weeks) decreased acetylcholinesterase (AChE) activity significantly (64% of control) in hypothalamus and increased AChE activity in cerebral cortex (149% of control), whereas, malondialdehyde (MDA) levels increased in hypothalamus (129% of control) and decreased in cortex, striatum, and cerebellum (50%, 69% and 75% of control), respectively. 3. Chronic ethanol ingestion (2.0 gm/kg, p.o. for 6.5 weeks) significantly increased butyrylcholinesterase (BuChE) activity in plasma (136% of control) and decreased AChE activity in hypothalamus (63% of control), whereas, MDA levels increased in hypothalamus, cortex, and plasma (140%, 130% and 220% of control), respectively. 4. The combination significantly increased BuChE activity (173% of control) in plasma and decreased AChE activity (71% of control) in hypothalamus and (57% of control) in cerebellum, whereas, MDA levels increased in hypothalamus, cerebellum, medulla and plasma (134%, 128%, 140% and 309% of control), respectively. 5. Exercise training, chronic ethanol ingestion, and combination selectively inhibited hypothalamic AChE and the inhibition was correlated with increased lipid peroxidation (r = 0.11, 0.41 and 0.45) which may perturb hypothalamic function. The combination enhanced the peripheral stress response by increasing plasma BuChE activity and lipid peroxidation.

Influence of exercise and ethanol on cholinesterase activity and lipid peroxidation in blood and brain regions of rat

1. This study elucidates the interaction of acute exercise and single ethanol intake on cholinergic enzyme and its relationship to lipid peroxidation in the blood and brain regions of the rat. 2. Butyrylcholinesterase (BuChE) in plasma and acetylcholinesterase (AChE) in brain regions as well as lipid peroxidation (MDA) were assayed in 1) sedentary control rats; 2) after acute exercise (100% VO2max); 3) ethanol 20% (1.6 gm/kg, p.o.); 4) exercise and then ethanol 20% (1.6 gm/kg, p.o.). 3. Acute exercise significantly increased BuChE activity (155% of control) in plasma and decreased AChE activity (60% of control) in the corpus striatum with a significant increase in the striatal MDA level (254% of control). Ethanol significantly decreased AChE activity only in striatum (86% of control) with a significant increase in striatal MDA level (132% of control). 4. The combination of exercise and ethanol 20% (1.6 gm/kg, p.o.) significantly increased BuChE activity (123% of control) in plasma, and decreased AChE activity (76% of control) in striatum with significant increase in striatal MDA level (147% of control). 5. Acute exercise, single ethanol 20% (1.6 gm/kg, p.o.) intake and the combination selectively inhibited striatal AChE, and the inhibition was correlated with increased lipid peroxidation indicating perturbation of motor function. The combination reduced the peripheral stress response caused by exhaustive exercise.

Area-specific modification of acetylcholinesterase activity following 3-mercaptopropionic acid-induced seizures

Acetylcholinesterase activity (AChE) was assayed in rat CNS membrane fractions after administration of the convulsant 3-mercaptopropionic acid (150 mg/kg, ip). In comparison with saline-injected controls, total AChE activity decreased 12-20% in striatum and cerebellum during seizure and postseizure but failed to change in cerebral cortex. Specific AChE activity, assayed in the presence of 10(-4) M ethopropazine (a butyrylcholinesterase inhibitor), decreased 15-25% in striatum and cerebellum, increased 20-45% in hippocampus, but remained unchanged in cerebral cortex. Saline injection alone increased AChE activity in striatum (68%) and cerebellum (36%) but failed to modify enzyme activity in hippocampus and cerebral cortex. To conclude, AChE sensitivity to convulsant and saline administration is tissue-specific and not restricted to cholinergic areas.