Brain Acetylcholinesterase Levels Research Articles

Effect of Toxicity of Chromium (VI) Stressors Alone and Combined to High Temperature on the Histopathological, Antioxidation, Immunity, and Energy Metabolism in Fish Phoxinus lagowskii

Fish in aquatic ecosystems are often impacted by environmental stressors like temperature fluctuations and exposure to heavy metals. Chromium (Cr6+) is a known environmental pollutant that poses a threat to aquatic life. Various environmental factors, such as water temperature, have been found to affect the toxicity of dissolved chemicals in aquatic ecosystems. We investigated the toxicity of combinations of different concentrations of hexavalent chromium (Cr6+) with high temperatures in fish. Hematological indices demonstrated changes in white blood cells (WBCs), hematocrit (HCT), red blood cells (RBCs), and hemoglobin (Hb) levels during the exposure. The qualitative and semi-quantitative analyses of different tissues confirmed that higher concentrations of Cr6+ caused more significant damage than lower concentrations, with evident alterations observed in circulatory and regressive aspects. Furthermore, brain acetylcholinesterase levels decreased in both single heavy metal exposure and combined exposure at a high temperature. The activity of antioxidant oxidase and immunological parameters increased in all treatment groups compared with the control group following long-term exposure. A significant and increased effect of Cr6+ in the high-temperature groups was observed on the evaluated biomarkers, suggesting a possible synergistic effect between Cr6+ and increased temperature. The integrated biomarker response (IBR) reported the highest level of stress at 10 mg/L Cr6+ combined with high temperature. The IBR analysis revealed that the highest activity of response enzymes, such as acid phosphatase (ACP), superoxide dismutase (SOD), and glutathione S-transferases (GST), was observed in the liver, whereas the gills displayed alkaline phosphatase (ALP), GST, and SOD activity, and the kidneys demonstrated SOD, ACP, and aspartate aminotransferase (AST) to be most active. Through histopathology, antioxidant enzymes, and metabolism- and immunity-related enzymes, we determined that high temperatures enhance the potential toxicity of Cr6+ in fish. We recommend conducting a thorough assessment of the impact of climate change, particularly temperature fluctuations, when studying the toxic effects of metal pollution, like chromium, in aquatic ecosystems.

Adansonia digitata L. fruit shell prevents aluminum-induced cognitive impairment and depression in rats

PurposeAluminum exposure can lead to free radicals production and increased susceptibility to lipids peroxidation in the central nervous system. The was aimed at evaluating the role of acetone extract of A. digitata shell acetone extract (ASAE) on oxidative stress, acetylcholinesterase (AChE) level, and hippocampal histology of aluminum chloride (AlCl3)-treated rats. MethodsTwenty-five rats were allotted into five groups (n = 5). The groups received distilled water, 250 mg/kg aluminum chloride, 250 mg/kg ASAE plus AlCl3, 500 mg/kg ASAE plus AlCl3, and 200 mg/kg Vitamin C plus AlCl3 respectively once daily for sixty days. Modified elevated plus maze (mEPM) and force swim test was conducted after 24 h. One half of the rat brain was homogenized and used to evaluate AChE level and oxidative stress biomarkers while the other half was processed for light microscopy. ResultsPre-treatment with ASAE was shown to significantly decrease (p < .05) the first transfer latency of mEPM and immobility time of the force swim test relative to the AlCl3-treated rats. The brain AChE level was significantly increased (p < .05) in rats treated with AlCl3 relative to the control. ASAE was found to regulate the AChE level. ASAE was found to significantly elevate (p < .05) superoxide dismutase and catalase activity relative to the control and AlCl3-treated rats. ConclusionsThe findings of the current study revealed that ASAE could prevent AlCl3-induced cognitive impairment and depression. It also regulated brain AChE levels and enhanced antioxidant activity. These suggest that ASAE could serve as a natural product for preventing oxidative stress-related diseases.

Protective effect of hot peppers against amyloid β peptide and brain injury in AlCl3-induced Alzheimer's disease in rats.

This study investigated the therapeutic effect of red hot pepper (Capsicum annuum) methanolic extract in induced Alzheimer's disease using AlCl3 in male rats. Rats were injected with AlCl3 intraperitoneally (IP) daily for two months. Starting from the 2nd month of AlCl3, rats received, in addition, IP treatments with Capsicum extract (25 and 50 mg/kg) or saline. Other groups received only saline or Capsicum extract at 50 mg/kg for two months. Brain levels of reduced glutathione (GSH), nitric oxide (NO), and malondialdehyde (MDA) were determined. Additionally, paraoxonase-1 (PON-1) activity, interleukin-6 (IL-6), Aβ-peptide, and acetylcholinesterase (AChE) concentrations in the brain were measured. Behavioral testing included wire-hanging tests for neuromuscular strength and memory tests such as Y-maze and Morris water maze. Histopathology of the brain was also done. Compared with saline-treated rats, AlCl3 caused significant elevation of brain oxidative stress as GSH level and PON-1 activity were depleted along with MDA and NO level elevation in the brain. There were also significant increases in brain Aβ-peptide, IL-6, and AChE levels. Behavioral testing indicated that AlCl3 decreased neuromuscular strength and impaired memory performance. Capsicum extract given to AlCl3-treated rats significantly alleviated oxidative stress and decreased Aβ-peptide and IL-6 in the brain. It also improved grip strength and memory functioning and prevented neuronal degeneration in the cerebral cortex, hippocampus, and substantia nigra of AlCl3-treated rats. Short-term administration of ASA (50 mg/kg) has adverse effects on male reproductive function in mice. Co-administration of melatonin protects against ASA-induced impairment of male reproductive function by preventing the reduction in serum TAC and testosterone levels seen with ASA treatment alone.

Selenium nanoparticles impart robust neuroprotection against deltamethrin-induced neurotoxicity in male rats by reversing behavioral alterations, oxidative damage, apoptosis, and neuronal loss

This study investigated the neuroprotective role of selenium nanoparticles (SeNPs) on deltamethrin-induced neurotoxicity in rats. A total of 32 adult male Wister rats were allocated into the following four groups: 1) control, 2) deltamethrin (0.6 mg/kg), 3) SeNPs (0.5 mg/kg), and 4) deltamethrin + SeNPs. All agents were administered orally three times per week for 2 months. Locomotor behavior, anxiety-like behavior, biochemical parameters, including brain oxidative damage biomarkers (Malondialdehyde (MDA) and reduced glutathione (GSH)), brain acetylcholinesterase (AChE), and brain genotoxicity were evaluated. The gene expression levels of IGF-1 and Bcl2 were also determined. Moreover, a brain histopathological examination associated with the immunohistochemical determination of Bax in brain tissue was performed. Deltamethrin-intoxicated rats showed a reduction in the locomotor activity associated with a highly anxious state. They also displayed a disturbance in the brain redox state with a decrease in the brain AChE levels and a high DNA fragmentation percentage. Furthermore, they showed a decrement in the immunohistochemical GFAP levels as well as IGF-1 and Bcl2 gene expression levels with an increase in the immunohistochemical Bax levels. All these changes were confirmed by brain histopathology. Interestingly, SeNPs ameliorated all these changes and restored the normal brain architecture. In conclusion. SeNPs possess a potent medicinal activity due to their antioxidant and anti-inflammatory activity. Therefore, SeNPs can be a potential agent in ameliorating deltamethrin-induced neurotoxicity.

Multi-biomarker approach to evaluate the neurotoxic effects of environmentally relevant concentrations of phenytoin on adult zebrafish Danio rerio

Several studies have reported the presence of phenytoin (PHE) in wastewater treatment plant effluents, hospital effluents, surface water, and even drinking water. However, published studies on the toxic effects of PHE at environmentally relevant concentrations in aquatic organisms are scarce. The present study aimed to determine the effect of three environmentally relevant concentrations of PHE (25, 282, and 1500 ng L−1) on behavioral parameters using the novel tank test. Moreover, we also aimed to determine whether or not these concentrations of PHE may impair acetylcholinesterase (AChE) activity and oxidative status in the brain of Danio rerio adults. Behavioral responses suggested an anxiolytic effect in PHE-exposed organisms, mainly observed in organisms exposed to 1500 ng L−1, with a significant decrease in fish mobility and a significant increase in activity at the top of the tank. Besides the behavioral impairment, PHE-exposed fish also showed a significant increase in the levels of lipid peroxidation, hydroperoxides, and protein carbonyl content compared to the control group. Moreover, a significant increase in brain AChE levels was observed in fish exposed to 282 and 1500 ng L−1. The results obtained in the present study show that PHE triggers a harmful response in the brain of fish, which in turn generates fish have an anxiety-like behavior.

Experimental validation of Vitex negundo leaves hydroalcoholic extract for neuroprotection in haloperidol induced parkinson's disease in rat.

Parkinsonism is a neurodegenerative disease, mainly imbalance in dopamine and acetylcholine neurotransimitter in mid brain, which manifestation of dysfunctions of extrapyramidal like akinesia, tremor, rigidity and catalepsy etc., even cognitive and memory loss. The current study is framed to evaluate the effect of Vitex negundo (VNL) leaf extract in Haloperidol induced PD in rats. In vitro studies of antioxidant capacity were checked via DPPH and NO assays and identified its Acetylcholinesterase (AChE) inhibitory activity. Secondly the In vivo study of anti-PD activity in Haloperidol induced in rats were evaluated by Rotarod, morris water maze (MWM), cooks pole climb (CPC), actophotometer, novel object recognition (NOR), and T-maze were utilized to assess extrapyramidal, cognitive and memory function. Thirdly, changes in biomarker level viz. (AChE), butyrylcholinesterase. (BChE) in hippocampus and cortex, reduced glutathione (GSH), malondialdehyde (MDA), total protein (TP), superoxide dismutase (SOD), catalase (CAT), and dopamine level in the whole brain were measured. Finally, histopathology of hippocampus and cortex was examined at 40x magnification to access restoring integrity and maintaining the architecture of neuronal cell in the treatment group compared to control group and L-DOPA as a standard treatment group. V. negundo showed potent antioxidant potency on scavenging of DPPH (IC50 84.81μg/ml) and NO (IC50 133.20μg/ml) and possess AChE inhibitory potency (IC50 114.35μg/ml) by in vitro studies. The Rotarod, MWM, CPC, Actophotometer, NOR, T-maze demonstrated that Haloperidol group administration declines performance time, ELT, TL and decreases locomotion, cognitive and memory respectively. The treatment of VNL 100, 200, and 400mg/kg p.o. significantly (p < 0.05 to p < 0.0001) reversed. Whole brain AChE, BChE, and MDA level were significantly raised and GSH, TP, SOD, CAT and Dopamine were significantly declined in Haloperidol treated group rats, especially V. negundo 400mg/kg p.o. highly significantly ameliorate the Haloperidol group altered pathological changes through the restoration of the cholinergic function, enhancing the antioxidant defense and by increasing the dopaminergic function. The current study provides validation of V. negundo for its anti-PD activity and could be a valuable source for the treatment of PD in future.

Chronic treatment with Escitalopram Reversed Scopolamine-induced Memory Impairment by enhancing Cholinergic activity in Wistar albino Rats

Objective: Escitalopram is one of the commonly used antidepressants. The use of antidepressants is increasing throughout the world. There is minimal evidence on the effect of chronic administration of escitalopram on scopolamine-induced memory impairment. So, the current study was aimed at evaluating the effects of chronic escitalopram administration on learning and memory in Wistar albino rats. Methods: Twenty-four adult male Wistar rats were randomly assigned equally to four groups, i.e., Control, scopolamine and two doses of escitalopram. The test drug was given orally for 28 days. Scopolamine was given single dose intraperitoneally. The rats were subjected to two behavioural paradigms, i.e., water maze and T maze. After behavioural tests, the rats were sacrificed. Brain acetylcholinesterase level was estimated, and histopathological examination was done. Results: Higher dose of escitalopram was able to reverse scopolamine-induced memory impairment both in the water maze and T maze. Escitalopram at this dose could also reverse the scopolamine-induced increase in brain acetylcholinesterase and histopathological changes. Conclusion: Chronic administration of escitalopram reversed scopolamine-induced memory impairment in a dose-dependent manner by enhancing cholinergic activity.

Impacts of chronic exposure to sublethal diazepam on behavioral traits of female and male zebrafish (Danio rerio)

Residues of the psychoactive drug diazepam (DZP) may pose potential risks to fish in aquatic environments, especially by disrupting their behavioral traits. In this study, female and male zebrafish were subjected to chronic exposure (21 days) to sublethal doses (120 and 12 µg/L) of DZP, aimed to compare the characteristics of their behavioral responses to DZP exposure, and to investigate the possible links between those behavioral responses and variations in their brain γ-aminobutyric acid (GABA) and acetylcholinesterase (AChE) levels. Chronic exposure to DZP significantly decreased the swimming velocity and locomotor activity of both genders, indicating a typical sedative effect. Compared with males, whose locomotor activity was only significantly decreased by exposure to DZP for 21 days, females became hypoactive on day 14 (i.e., more sensitive), and they developed tolerance to the hypoactive effect induced by 120 μg/L DZP by day 21. Exposure to DZP significantly disturbed the behavioral traits related to social interactions in females but not in males. Those results indicate that DZP exhibits sex-dependent effects on the behaviors of fish. Moreover, exposure to DZP for 21 days significantly disturbed almost all of the tested behavioral traits associated with courtship when both genders were put together. Sex-dependent responses in brain GABA and AChE levels due to DZP exposure were also identified. Significant relationships between the brain GABA/AChE levels and some behavioral parameters related to locomotor activity were detected in females, but not in males.

Amelioration of Cognitive Deficits, Oxidative Damage, Neurochemical Alteration by Bauhinia purpurea (stem bark) on Scopolamine Induced Amnesia

Aim: To evaluate the anti-amnesia effect of Bauhinia purpurea in Scopolamine induced amnesia in rats. Materials and Methods: A total of 30 rats were divided into 5 groups 6 rats in each. Group I considered as normal control. Group II served as negative control. Group III, IV and V were treated with Donepezil (3 mg/kg), ethanolic extract of Bauhinia purpurea 200mg/kg and 400 mg/kg respectively for 14 consecutive days followed by single administration of Scopolamine (3 mg/kg) to all the groups except group I. Cognitive performance was assessed by the Morris water maze, elevated plus maze and passive avoidance paradigm. Acetyl cholinesterase enzyme level, biochemical markers such as lipid peroxidation, reduced glutathione and β amyloid 1 42 level, Neurotransmitters including dopamine and serotonin and histopathological study of rat brain were estimated. Results: Bauhinia purpurea and Donepezil rats showed significant increase in escape latency, step-through latency and decreased transfer latency in respective cognitive models of the Morris water maze, passive avoidance test and elevated plus maze. Additionally, Bauhinia purpurea extract remarkably promoted the cholinergic neurotransmission, decreasing β amyloid protein and protected against the oxidative stress damage as indicated by, increasing reduced glutathione level, lowering the level of lipid peroxidation, restored dopamine and serotonin level in the brain. Furthermore, histopathological studies revealed the reversal of neuronal damage in the treatment group compared to Scopolamine treated rats. Conclusion: Bauhinia purpurea extract showed promising antiamnesia activity against scopolamine induced amnesia in rats. This could be attributed to its brain acetyl cholinesterase level, β amyloid level inhibition, antioxidant activity and alteration in neurotransmitters level. Key words: Bauhinia purpurea, Neuroprotective, Acetylcholinesterase, β amyloid protein, Scopolamine.

Cholinergic denervation in patients with idiopathic rapid eye movement sleep behaviour disorder.

Cholinergic dysfunction appears to play a role in the cognitive impairment observed in Parkinson's disease and dementia with Lewy bodies. The occurrence of cholinergic dysfunction in the early stages of these conditions, however, has not been investigated. The objective of this study was to investigate cholinergic function in patients with idiopathic rapid eye movement sleep behaviour disorder (iRBD), a disorder recognized to be an early stage of both Parkinson's disease and dementia with Lewy bodies. A total of 21 patients with polysomnography-confirmed iRBD with no evidence of parkinsonism and cognitive impairment and 10 controls underwent positron emission tomography (PET) to assess brain acetylcholinesterase levels (11 C-donepezil PET) and nigrostriatal dopaminergic function (18 F-DOPA PET). Clinical examination included the Movement Disorder Society-Unified Parkinson's Disease Rating Scale part III, Mini Mental State Examination and Montreal Cognitive Assessment. The 11 C-donepezil PET was successfully performed in 17 patients with iRBD and nine controls. Compared with controls, patients with iRBD showed a mean 7.65% reduction in neocortical 11 C-donepezil levels (P=0.005). Bilateral superior temporal cortex, occipital cortex, cingulate cortex and dorsolateral prefrontal cortex showed the most significant reductions at voxel level. Reduced neocortical 11 C-donepezil binding in our patients indicates cholinergic denervation and suggests that the projections from the nucleus basalis of Meynert, which supplies cholinergic innervation to the neocortex, are dysfunctional in iRBD. Longitudinal studies will clarify if these changes are predictive of future cognitive impairment in these patients.

Antidepressants Modulate Behavioral, Biochemical, and Histological Alterations Induced by Chronic Aluminum Chloride Administration in Wistar Rats

Objective: To assess the effect of duloxetine and escitalopram on aluminum chloride (AlCl3)‑induced memory impairment in rats. Materials and Methods: Thirty rats were used. Group‑I (control) and Group‑II (toxic control) received 2% gum acacia, 10 mL/kg and AlCl3, 175 mg/kg, respectively. Group‑III (standard), Group‑IV, and Group‑V (test drug groups) received rivastigmine (1 mg/kg), duloxetine (10 mg/kg), and escitalopram (10 mg/kg), respectively, along with AlCl3, 175 mg/kg. All drugs and AlCl3 were administered orally daily for 2 months. The effect on cognition was assessed by Morris water maze (MWM). Brain acetylcholinesterase levels, oxidative stress parameters, and histology of the hippocampus were also evaluated. Results: Rats treated with only AlCl3 showed significant (P < 0.001) increase in latency during acquisition trials of day‑3 and day‑4 and decrease in percentage of both time spent and distance traveled in target zone during probe trial in MWM. Malondialdehyde was increased and glutathione decreased in the brain. Histopathology of the hippocampus showed unhealthy cellular architecture with a large number of degenerated cells. All these changes were significantly reversed in rivastigmine and test drug groups. Chronic administration of AlCl3 resulted in lowering of brain cholinesterase levels (P < 0.001) versus control. Cholinesterase levels were further significantly (P < 0.05) lowered in rats who received AlCl3 along with either rivastigmine or escitalopram. Conclusion: Escitalopram and duloxetine exerted a protective effect against AlCl3‑induced memory impairment in rats.

Lavandula stoechas (L) a Very Potent Antioxidant Attenuates Dementia in Scopolamine Induced Memory Deficit Mice.

The objective of the current project was to explore the pharmacotherapeutic role of Lavandula stoechas (L) for the management of dementia. Dementia is considered a global challenge of current century seeking special attention of pharmacologists to explore its best remedies. Methanolic extract of aerial parts of L. stoechas was tested for phytochemical analysis along with free radical scavenging activity. Behavioral studies were performed on scopolamine induced amnesic mice by using elevated plus maze (EPM), light and dark test and hole board paradigms. Biochemical investigations were made after decapitating the mice. Their brains were isolated for biochemical estimation of acetylcholinesterase (AChE), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH). Phytochemical study ensured the presence of total phenolic contents (285.91 ± 0.75 mg of GAE/g of extract), total flavonoids (134.06 ± 0.63 mg of RE/g of extract), total tannins (149.60 ± 0.93 mg of TAE/g of extract) and free radical scavenging activity (IC50 value = 76.73 μg/ml found by DPPH method). Behavioral studies indicated that animals of GVII showed higher inflexion ratio (0.40 ± 0.03) for EPM, spent most of time (227.17 ± 2.13 s) in dark area of light dark test and had many hole pockings (39.83 ± 1.88) for hole board paradigm. Moreover, biochemical studies revealed that methanolic extract of L. stoechas (800 mg/kg/p.o.) significantly (P < 0.001) reduced brain AChE and MDA levels while improved SOD, CAT, and GSH levels. Thus the findings suggest that L. stoechas stabilizes memory by enhancing cholinergic neurotransmission and by providing defense against oxidative stress in mice brain.

Potentiation of nootropic activity of EGCG loaded nanosuspension by piperine in swiss male albino mice

The present study deals with preparation of nanoformulations of epigallocatchin gallate (EGCG) alone and with piperine, and evaluation of in vivo cognitive effect on Swiss albino male mice. EGCG (25 mg) was nanoencapsulated into a biocompatible and biodegradable protein nanocarrier, zein and was also separately nanoencapsulated with piperine (5 mg), a bioenhancer. Anti-solvent precipitation method was used for formulation of EGCG loaded nanosuspension and EGCG-Piperine nanocomplex. EGCG loaded nanosuspension (25 mg kg−1) and EGCG-Piperine nanocomplex (25 mg kg−1) were administered per se to mice for 3 successive weeks. The behaviour models i.e. Elevated plus maze and Morris water maze were used for assessing the cognitive behaviour. The influence of various drug treatments on locomotor activity of mice was also studied. The mice were sacrificed on 21st day followed by estimation of brain acetylcholinesterase activity. The significant reversion in scopolamine-induced amnesia in mice was observed after administration of EGCG loaded nanosuspension (25 mg kg−1) and EGCG-Piperine nanocomplex (25 mg kg−1). A significant reduction in brain acetylcholinesterase level in mice was observed after the administration of physostigmine (0.1 mg kg−1), EGCG loaded nanosuspension (25 mg kg−1) and EGCG-Piperine nanocomplex (25 mg kg−1). The oral administration of EGCG loaded nanosuspension for three successive weeks significantly improved cognitive behaviour in mice; and piperine potentiated the cognitive effect of EGCG loaded nanosuspension. Further, EGCG loaded nanosuspension showed improved cognitive behaviour in mice probably through inhibition of brain acetylcholinesterase activity, and facilitation of cholinergic pathways.

Personalized genetics of the cholinergic blockade of neuroinflammation.

Acetylcholine signaling is essential for cognitive functioning and blocks inflammation. To maintain homeostasis, cholinergic signaling is subjected to multi‐leveled and bidirectional regulation by both proteins and non‐coding microRNAs (‘CholinomiRs’). CholinomiRs coordinate the cognitive and inflammatory aspects of cholinergic signaling by targeting major cholinergic transcripts including the acetylcholine hydrolyzing enzyme acetylcholinesterase (AChE). Notably, AChE inhibitors are the only currently approved line of treatment for Alzheimer's disease patients. Since cholinergic signaling blocks neuroinflammation which is inherent to Alzheimer's disease, genomic changes modifying AChE's properties and its susceptibility to inhibitors and/or to CholinomiRs regulation may affect the levels and properties of inflammasome components such as NLRP3. This calls for genomic‐based medicine approaches based on genotyping of both coding and non‐coding single nucleotide polymorphisms (SNPs) in the genes involved in cholinergic signaling. An example is a SNP in a recognition element for the primate‐specific microRNA‐608 within the 3′ untranslated region of the AChE transcript. Carriers of the minor allele of that SNP present massively elevated brain AChE levels, increased trait anxiety and inflammation, accompanied by perturbed CholinomiR‐608 regulatory networks and elevated prefrontal activity under exposure to stressful insults. Several additional SNPs in the AChE and other cholinergic genes await further studies, and might likewise involve different CholinomiRs and pathways including those modulating the initiation and progression of neurodegenerative diseases. CholinomiRs regulation of the cholinergic system thus merits in‐depth interrogation and is likely to lead to personalized medicine approaches for achieving better homeostasis in health and disease. This is an article for the special issue XVth International Symposium on Cholinergic Mechanisms.

Protection of zonisamide induced memory impairment by tulsi extract and piracetam on mice

Background: Memory impairment is the major adverse effects associated with antiepileptic drug therapy. This study was designed to assess the memory impairment activity of zonisamide (ZNS), an antiepileptic drug, in mice. Memory deficit potential of ZNS was compared with phenytoin (PHT), a standard antiepileptic known for its memory impairment activity. The protective effect of Ocimum sanctum extract (OS) and piracetam (PIR) on memory impairment induced by ZNS was also assessed. Materials and Methods: ZNS was administered orally for 29 days and the extent of memory deficit was evaluated by Morris water maze (MWM) test on maximal electro shock-induced epileptic mice. The animals were observed for escape latency time (ELT) and time spent in target quadrant (TSTQ) on MWM test. The brain acetylcholinesterase level was estimated to determine the brain acetylcholine concentration. Result: Chronic administration of ZNS has shown memory deficit in mice and this was significantly restored by co-administration of OS extract and PIR. PIR showed best nootropic activity, whereas OS showed good nootropic as well as synergistic anti-convulsant activity. Conclusion: This study reveals that chronic administration of ZNS produces memory impairment in mice, which can be significantly minimized by co-administration of OS extract and PIR without compromising on ZNS antiepileptic potency. These results provide evidence for potential corrective effect of nootropics in cognitive deficit associated with ZNS.

P03-81 - Cognition improving effects of clerodendron phlomidis linn. bark extract in mice

Normal ageing is known to deteriorate memory in human beings. Oxygen free radicals, the harmful byproducts of oxidative metabolism are known to cause organic damage to the living system, which may be responsible for the development of Alzheimer's disease in elderly. Clerodendron phlomidis Linn. (Verbenaceae) is known as Agnimantha in sanskrit. Bark of the plant is used in treating various nervous disorders. In the present study C. phlomidis was investigated for its potential as a nootropic agent in mice. The aqueous extract of the C. phlomidis (100 and 200 mg/kg, p.o.) was administered for 6 successive days to both young and aged mice. Exteroceptive behavioral models such as elevated plus maze and passive avoidance paradigm were employed to evaluate short term and long term memory respectively. Scopolamine, diazepam were used to induce amnesia in mice. To delineate the mechanism by which C. phlomidis exerts nootropic action, its effect on brain acetyl cholinesterase levels were determined. Piracetam was used as a standard nootropic agent. Pretreatment with C. phlomidis (100 and 200 mg/kg, p.o.) for 6 successive days significantly improved learning and memory in mice. It reversed the amnesia induced by scopolamine, diazepam and natural ageing. It also decreased the acetyl cholinesterase levels in the whole brain. The bark of C. phlomidis can be useful in treatment of cognitive disorders such as amnesia and Alzheimer's disease.

Antiamnesic evaluation of C. phlomidis Linn. bark extract in mice

Clerodendron phlomidis Linn. (Verbenaceae) is known as Agnimantha in sanskrit. Bark of the plant is used in treating various nervous disorders. In the present study C. phlomidis was investigated for its potential as a nootropic agent in mice. The aqueous extract of the C. phlomidis (100 and 200 mg/kg, p.o.) was administered for 6 successive days to both young and aged mice. Exteroceptive behavioral models such as elevated plus maze and passive avoidance paradigm were employed to evaluate short term and long term memory respectively. Scopolamine (0.4 mg/kg, i.p.), diazepam (1 mg/kg, i.p.) were employed to induce amnesia in mice. To delineate the mechanism by which C. phlomidis exerts nootropic action, its effect on brain acetyl cholinesterase levels were determined. Piracetam (200 mg/kg, i.p.) was used as a standard nootropic agent. Pretreatment with C. phlomidis (100 and 200 mg/kg, p.o.) for 6 successive days significantly improved learning and memory in mice. It reversed the amnesia induced by scopolamine, diazepam and natural ageing. It also decreased the acetyl cholinesterase levels in the whole brain. The bark of C. phlomidis can be of enormous use in the management of treatment of cognitive disorders such as amnesia and Alzheimer's disease.

Inhibition of acetylcholinesterase in CSF versus brain assessed by 11C-PMP PET in AD patients treated with galantamine

The relationship between acetylcholinesterase (AChE) activity in the CSF and brain of patients with Alzheimer's disease (AD) was investigated in 18 mild AD patients following galantamine treatment. The first 3 months of the study had a randomized double-blind placebo-controlled design, during which 12 patients received galantamine (16–24 mg/day) and six patients placebo. This was followed by 9 months galantamine treatment in all patients. Activities and protein levels of both the “read-through” AChE (AChE-R) and the synaptic (AChE-S) variants in CSF were assessed in parallel together with the regional brain AChE activity by 11C-PMP and PET. The AChE-S inhibition was 30–36% in CSF, which correlated well with the in vivo AChE inhibition in the brain. No significant AChE inhibition was observed in the placebo group. The increased level of the AChE-R protein was 16% higher than that of AChE-S. Both the AChE inhibition and the increased level of AChE-R protein positively correlated with the patient's performance in cognitive tests associated with visuospatial ability and attention. In conclusion, AChE levels in CSF closely mirror in vivo brain AChE levels prior to and after treatment with the cholinesterase inhibitors. A positive cognitive response seems to dependent on the AChE inhibition level, which is balanced by an increased protein level of the AChE-R variant in the patients.

Brain acetylcholinesterase as a marine pesticide biomarker using Brazilian fishes

Brain acetylcholinesterase (AChE) of some fishes from the coast of Rio de Janeiro State was studied as a possible pesticide biomarker in marine environmental monitoring. AChE specific activity in brain varied from 145 to 530 U/g of proteins and the Michaelis-Menten constant (K(M)) for acetylthiocholine varied from 104 to 291 microM among the 20 species studied. The enzyme sensitivity to methyl paraoxon, evaluated by the inhibition kinetic constants, shows that some species (Paralonchurus brasiliensis and Genidens genidens) are more sensitive (IC50-30 min=455 and 468 nM, respectively). The less sensitive Merluccius hubbsi and Percophis brasiliensis (IC50-30 min=3339 and 3259 nM, respectively) belong to the super-order Paracanthopterygii, which includes the more ancient species. On the other hand, more susceptible species belong to the super-order Acanthopterygii, which includes more recent species. These results suggest a possible evolutionary linkage for AChE sensitivity to methyl paraoxon. The application of inhibition kinetic constants for fish brain AChE in phylogenetic studies is still being investigated. The results have shown that a fish sentinel species should have the highest brain AChE level among the more sensitive ones.

Mecamylamine interactions with galantamine and donepezil: effects on learning, acetylcholinesterase, and nicotinic acetylcholine receptors

Patch-clamp recordings of single ion channel activity demonstrated that donepezil, but not galantamine, could be blocked by the nicotinic cholinergic antagonist mecamylamine, suggesting that galantamine acted at a separate (allosteric) site. The aim of this experiment was to demonstrate at a whole organism, behavioral level that galantamine, but not donepezil, could reverse mecamylamine-induced learning impairment. Forty-four young female rabbits received 15 sessions in the 750-ms delay eyeblink classical conditioning procedure, after one of five drug treatments: 0.5 mg/kg mecamylamine, 3.0 mg/kg donepezil, 0.5 mg/kg mecamylamine plus 3.0 mg/kg galantamine, 0.5 mg/kg mecamylamine plus 3.0 mg/kg donepezil, or sterile saline vehicle. An additional 24 young female rabbits were tested in the explicitly unpaired condition after treatment with the same mecamylamine plus galantamine or donepezil combinations or with vehicle. In a previous study we demonstrated that 3.0 mg/kg galantamine facilitated learning in young rabbits. Donepezil (3.0 mg/kg) did not facilitate learning in this experiment. However, both galantamine and donepezil reversed the deleterious effects of mecamylamine on learning. Significant differences in plasma and brain acetylcholinesterase levels were detected among the drug treatment groups. Fifteen daily injections did not produce statistically significant changes in nicotinic receptor binding in any of the five treatment groups. One possible interpretation of these results is that donepezil affected nicotinic acetylcholine receptors by raising the synaptic level of acetylcholine and hence, the probability of receptor activation, whereas galantamine bound to distinct allosteric sites not blocked by mecamylamine.