Organosulfur compound protects against memory decline induced by scopolamine through modulation of oxidative stress and Na+/K+ ATPase activity in mice

A Purine Derivative Containing an Organoselenium Group Protects Against Memory Impairment, Sensitivity to Nociception, Oxidative Damage, and Neuroinflammation in a Mouse Model of Alzheimer's Disease

In the present study, the effect of 6-((4-fluorophenyl) selanyl)-9H-purine (FSP) was tested against memory impairment and sensitivity to nociception induced by intracerebroventricular injection of amyloid-beta peptide (Aβ) (25-35 fragment), 3 nmol/3 μl/per site in mice. Memory impairment was determined by the object recognition task (ORT) and nociception by the Von-Frey test (VFT). Aβ caused neuroinflammation with upregulation of glial fibrillary acidic protein (GFAP) (in hippocampus), nuclear factor-κB (NF-κB), and the proinflammatory cytokines interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) in cerebral cortex and hippocampus. Additionally, Aβ increased oxidant levels and lipid peroxidation in cerebral cortex and hippocampus, but decreased heme oxygenase-1 (HO-1) and peroxiredoxin-1 (Prdx1) expression in the hippocampus. Anti-neuroinflammatory effects of FSP were demonstrated by a decrease in the expression of GFAP and NF-κB in the hippocampus, as well as a decrease in proinflammatory cytokines in both the hippocampus and cerebral cortex FSP protected against oxidative stress by decreasing oxidant levels and lipid peroxidation and by increasing HO-1 and Prdx1 expressions in the hippocampus of mice. Moreover, FSP prevented the activation of nuclear factor erythroid 2-related factor 2 (Nrf-2) in the hippocampus of mice induced by Aβ. In conclusion, treatment with FSP attenuated memory impairment, nociception sensitivity by decreasing oxidative stress, and neuroinflammation in a mouse model of Alzheimer's disease.

Recent Advances in the Study of Na+/K+-ATPase in Neurodegenerative Diseases

Na⁺/K⁺-ATPase (NKA), a large transmembrane protein, is expressed in the plasma membrane of most eukaryotic cells. It maintains resting membrane potential, cell volume and secondary transcellular transport of other ions and neurotransmitters. NKA consumes about half of the ATP molecules in the brain, which makes NKA highly sensitive to energy deficiency. Neurodegenerative diseases (NDDs) are a group of diseases characterized by chronic, progressive and irreversible neuronal loss in specific brain areas. The pathogenesis of NDDs is sophisticated, involving protein misfolding and aggregation, mitochondrial dysfunction and oxidative stress. The protective effect of NKA against NDDs has been emerging gradually in the past few decades. Hence, understanding the role of NKA in NDDs is critical for elucidating the underlying pathophysiology of NDDs and identifying new therapeutic targets. The present review focuses on the recent progress involving different aspects of NKA in cellular homeostasis to present in-depth understanding of this unique protein. Moreover, the essential roles of NKA in NDDs are discussed to provide a platform and bright future for the improvement of clinical research in NDDs.

A Pivotal Role of Nrf2 in Neurodegenerative Disorders: A New Way for Therapeutic Strategies

Clinical and preclinical research indicates that neurodegenerative diseases are characterized by excess levels of oxidative stress (OS) biomarkers and by lower levels of antioxidant protection in the brain and peripheral tissues. Dysregulations in the oxidant/antioxidant balance are known to be a major factor in the pathogenesis of neurodegenerative diseases and involve mitochondrial dysfunction, protein misfolding, and neuroinflammation, all events that lead to the proteostatic collapse of neuronal cells and their loss. Nuclear factor-E2-related factor 2 (Nrf2) is a short-lived protein that works as a transcription factor and is related to the expression of many cytoprotective genes involved in xenobiotic metabolism and antioxidant responses. A major emerging function of Nrf2 from studies over the past decade is its role in resistance to OS. Nrf2 is a key regulator of OS defense and research supports a protective and defending role of Nrf2 against neurodegenerative conditions. This review describes the influence of Nrf2 on OS and in what way Nrf2 regulates antioxidant defense for neurodegenerative conditions. Furthermore, we evaluate recent research and evidence for a beneficial and potential role of specific Nrf2 activator compounds as therapeutic agents.

A new arylsulfanyl-benzo-2,1,3-thiadiazoles derivative produces an anti-amnesic effect in mice by modulating acetylcholinesterase activity

The aim of the present study was investigate the binding affinity of 5-((4-methoxyphenyl)thio)benzo[c][1,2,5]thiadiazole (MTDZ) with acetylcholinesterase (AChE). We also evaluated the effect of MTDZ against scopolamine (SCO)-induced amnesia in mice and we looked at the toxicological potential of this compound in mice. The binding affinity of MTDZ with AChE was investigated by molecular docking analyses. For an experimental model, male Swiss mice were treated daily with MTDZ (10 mg/kg, intragastrically (i.g.)) or canola oil (10 ml/kg, i.g.), and induced, 30 min later, with injection of SCO (0.4 mg/kg, intraperitoneally (i.p.)) or saline (0.9%, 5 ml/kg, i.p.) daily. From day 1 to day 10, mice were submitted to the behavioral tasks (Barnes maze, open-field, object recognition and location, Y-maze and step-down inhibitory avoidance tasks), 30 min after induction with SCO. On the tenth day, the animals were euthanized and blood was collected for the analysis of biochemical markers (creatinine, aspartate (AST), and alanine (ALT) aminotransferase). MTDZ interacts with residues of the AChE active site. SCO caused amnesia in mice by changing behavioral tasks. MTDZ treatment attenuated the behavioral changes caused by SCO. In ex vivo assay, MTDZ also protected against the alteration of AChE activity, reactive species (RS) levels, thiobarbituric acid reative species (TBARS) levels, catalase (CAT) activity in tissues, as well as in transaminase activities of plasma caused by SCO in mice. In conclusion, MTDZ presented anti-amnesic action through modulation of the cholinergic system and provided protection from kidney and liver damage caused by SCO.

Protective Effects of Inosine on Memory Consolidation in a Rat Model of Scopolamine-Induced Cognitive Impairment: Involvement of Cholinergic Signaling, Redox Status, and Ion Pump Activities

This study investigated the effects of inosine on memory acquisition and consolidation, cholinesterases activities, redox status and Na⁺, K⁺-ATPase activity in a rat model of scopolamine-induced cognitive impairment. Adult male rats were divided into four groups: control (saline), scopolamine (1 mg/kg), scopolamine plus inosine (50 mg/kg), and scopolamine plus inosine (100 mg/kg). Inosine was pre-administered for 7 days, intraperitoneally. On day 8, scopolamine was administered pre (memory acquisition protocol) or post training (memory consolidation protocol) on inhibitory avoidance tasks. The animals were subjected to the step-down inhibitory avoidance task 24 hours after the training. Scopolamine induced impairment in the acquisition and consolidation phases; however, inosine was able to prevent only the impairment in memory consolidation. Also, scopolamine increased the activity of acetylcholinesterase and reduced the activity of Na⁺, K⁺-ATPase and the treatment with inosine protected against these alterations in consolidation protocol. In the animals treated with scopolamine, inosine improved the redox status by reducing the levels of reactive oxygen species and thiobarbituric acid reactive substances and restoring the activity of the antioxidant enzymes, superoxide dismutase and catalase. Our findings suggest that inosine may offer protection against scopolamine-induced memory consolidation impairment by modulating brain redox status, cholinergic signaling and ion pump activity. This compound may provide an interesting approach in pharmacotherapy and as a prophylactic against neurodegenerative mechanisms involved in Alzheimer's disease.

Investigation of alpha-lipoic acid effect on memory impairment considering strain-dependent differences in mice

AIMS

Memory impairment is regarded as one of the most challenging neurological disorders. The present study aimed to investigate behavioral and biochemical differences among similar mouse strains following Scopolamine (SCO) exposure as a widespread memory disturbing agent, and a supremely potent antioxidant, alpha-lipoic acid (ALA).

MATERIALS AND METHODS

Three sets of mouse strains (i.e. SW, NMRI, and NIH mice) were subjected to 2 mg/kg intraperitoneal SCO and/or 50 mg/kg ALA 30 min before each Morris Water Maze (MWM) trial for five consecutive days. Upon completion of the trials, the hippocampal region of the animals was dissected for histopathological and biochemical analyses.

KEY FINDINGS

The results exhibited significant impairments caused by SCO in behavioral tests, including probe test, escape latency, and distance traveled in two strains of NMRI and NIH. Nevertheless, at swimming speed, SCO had no meaningful effect on SW and NIH strains. The level of oxidative stress parameters including MDA, ROS, and SOD increased, FRAP and TTM levels related to the hippocampus decreased. There was also a significant increase in hippocampal acetylcholinesterase levels, ADP/ATP ratio, p-NFkB, and Cyt-c. Conversely, ALA administration resulted in a significant improvement in SCO-induced spatial learning and memory impairments only in the SW and NIH mice, which was associated with a significant reduction in hippocampal AChE activity, ADP/ATP ratio, ROS and MDA levels, and SOD activity.

SIGNIFICANCE

In addition of highlighting the efficacious role of ALA in cognitive functions, the findings of this study signified the behavioral dissimilarities among similar animal strains in case of different chemical exposures.

Multitarget Effect of 2-(4-(Methylthio)phenyl)-3-(3-(piperidin-1-yl)propyl)thiazolidin-4-one in a Scopolamine-Induced Amnesic Rat Model

Cholinergic system dysfunction, oxidative damage, and alterations in ion pump activity have been associated with memory loss and cognitive deficits in Alzheimer's disease. 1,3-thiazolidin-4-ones have emerged as a class of compounds with potential therapeutic effects due to their potent anticholinesterase activity. Accordingly, this study investigated the effect of the 2-(4-(methylthio)phenyl)-3-(3-(piperidin-1-yl)propyl)thiazolidin-4-one (DS12) compound on memory, cholinergic and oxidative stress parameters, ion pump activity, and serum biochemical markers in a scopolamine-induced memory deficit model. Male Wistar rats were divided into four groups: I-Control; II-Scopolamine; III-DS12 (5 mg/kg) + scopolamine; and IV-DS12 (10 mg/kg) + scopolamine. The animals from groups III and IV received DS12 diluted in canola oil and administered for 7 days by gavage. On the last day of treatment, scopolamine (1 mg/kg) was administered intraperitoneally (i.p.) 30 min after training in an inhibitory avoidance apparatus. Twenty-four hours after scopolamine administration, the animals were subjected to an inhibitory avoidance test and were thereafter euthanized. Scopolamine induced memory deficits, increased acetylcholinesterase activity and oxidative damage, and decreased Na+/K+-ATPase activity in cerebral cortex and hippocampus. Pretreatment with DS12 prevented these brain alterations. Scopolamine also induced an increase in acetylcholinesterase activity in lymphocytes and whereas butyrylcholinesterase in serum and treatment with DS12 prevented these changes. In animals treated with DS12, no changes were observed in renal and hepatic parameters when compared to the control group. In conclusion, DS12 emerged as an important multitarget compound capable of preventing neurochemical changes associated with memory deficits.

Therapeutic potential of selanyl amide derivatives in the in vitro anticholinesterase activity and in in vivo antiamnesic action

The present study evaluated the in vitro acetylcholinesterase (AChE) inhibitor activity of two new selanyl amide derivatives in cerebral structures of mice. Our results demonstrated that N-(2-(3-(phenylselanyl)propoxy)phenyl)furan-2-carboxamide (1) and N-(2-(3-(phenylselanyl)propoxy)phenyl)thiophene-2-carboxamide (2) inhibited the in vitro AChE activity in mice. Another objective was to assess the effect of the best AChE inhibitor in an amnesic model induced by scopolamine (SCO) in male Swiss mice. The involvement of AChE activity and lipid peroxidation in the cerebral structures was investigated. Our results showed that compound 1 (10 mg/kg, intragastrically) attenuated the latency to find the escape box and the number of holes visited in the Barnes maze task, without altering the locomotor and exploratory activities in an open-field test. Compound 1 protected against increasing in lipid peroxidation levels and AChE activity caused by SCO in the cerebral cortex and hippocampus of mice. In conclusion, the present study evidenced the in vitro anticholinesterase effect of two new selanyl amide derivatives in the cerebral structures of mice. Moreover, compound 1, a selanyl amide derivative containing a furan ring, demonstrated antiamnesic action due to its antioxidant and anticholinesterase activities in cerebral structures.

Amnesia-ameliorative effect of a quinoline derivative through regulation of oxidative/cholinergic systems and Na+/K+-ATPase activity in mice

The present study evaluated the anti-amnesic activity of 1-(7-chloroquinolin-4-yl)-5-methyl-N-phenyl-1H-1,2,3-triazole-4-carboxamide (QTCA-1) against scopolamine (SCO)-induced amnesia in mice. It was evaluated cholinergic dysfunction, oxidative stress and Na⁺/K⁺-ATPase activity in cerebral cortex and hippocampus of mice. Male Swiss mice were treated with QTCA-1 (10 mg/kg, intragastrically (i.g.), daily) for nine days. Thirty minutes after the treatment with compound, the animals received a injection of SCO (0.4 mg/kg, intraperitoneally (i.p.)). Mice were submitted to the behavioral tasks 30 min after injection of SCO (Barnes maze, open-field, object recognition and location, and step-down inhibitory avoidance tasks) during nine days. In day 9, cerebral cortex and hippocampus of mice were removed to determine the thiobarbituric acid reactive species (TBARS) levels, and catalase (CAT), Na⁺/K⁺-ATPase and acetylcholinesterase (AChE) activities. SCO caused amnesia in mice for changing in step-down inhibitory avoidance, Barnes maze, and object recognition and object location tasks. QTCA-1 treatment attenuated the behavioral changes caused by SCO. Moreover, SCO increased AChE and CAT activities, decreased Na⁺/K⁺-ATPase activity and increased TBARS levels in the cerebral structures of mice. QTCA-1 protected against these brain changes. In conclusion, QTCA-1 had anti-amnesic action in the experimental model used in the present study, through the anticholinesterase effect, modulation of Na⁺/K⁺-ATPase activity and antioxidant action.

Contribution of serotonergic and nitrergic pathways, as well as monoamine oxidase-a and Na+, K+-ATPase enzymes in antidepressant-like action of ((4-tert-butylcyclohexylidene) methyl) (4-methoxystyryl) sulfide (BMMS)

The present study investigated a possible antidepressant-like effect of ((4-tert-butylcyclohexylidene)methyl) (4-methoxystyryl) sulfide (BMMS) by using the forced swimming test (FST) and the tail suspension test (TST) in Swiss mice. The contribution of serotoninergic, glutamatergic and nitrergic systems in the antidepressant-like activity of BMMS was evaluated. We also examined the involvement of monoamine oxidase (MAO)-A, MAO-B and Na⁺, K⁺-ATPase activities in prefrontal cortex of mice. BMMS, (0.1-10 mg/kg, intragastrically (i.g.)) and fluoxetine (32 mg/kg, i.g.) decreased the immobility time in the FST and TST. The anti-immobility effect of BMMS (10 mg/kg, i.g.) in the TST was prevented by the pretreatment of mice with WAY100635 (0.1 mg/kg, subcutaneously (s.c.), a 5-HT_1A receptor antagonist), ketanserin (5 mg/kg, intraperitoneal (i.p.), a 5-HT_2A/2C receptor antagonist), and partially blocked by ondansetron (1 mg/kg, i.p., a 5-HT₃ receptor antagonist). The anti-immobility effect of BMMS (10 mg / kg, i.g.) was not avoided by pretreatment with MK-801 (0.01 mg/kg, s.c. a non-competitive N-methyl D-Aspartate (NMDA) receptor) in the TST. Pretreatment with L-arginine (500 mg/kg, i.p., a nitric oxide precursor) reversed partially the reduction in the immobility time elicited by BMMS (10 mg/kg, i.g.) in TST. BMMS altered Na⁺,K⁺-ATPase and MAO-A activities in prefrontal cortex of mice, but was not able to change the MAO-B activity. In conclusion, BMMS exerted an antidepressant-like effect in mice and serotonergic and nitrergic systems are involved in the antidepressant-like action of compound. BMMS modulated MAO-A and Na⁺, K⁺- ATPase activities in prefrontal cortex of mice.

Copper-mediated direct thiolation of aryl C–H bonds with disulfides

A directing group-assisted copper-mediated thiolation of aromatic amides with disulfides via direct C(sp²)–H activation has been developed.

Hippocampal Proteomic Alteration in Triple Transgenic Mouse Model of Alzheimer's Disease and Implication of PINK 1 Regulation in Donepezil Treatment

Donepezil is a clinically approved acetylcholinesterase inhibitor (AChEI) for cognitive improvement in Alzheimer's disease (AD). Donepezil has been used as a first-line agent for the symptomatic treatment of AD, but its ability to modify disease pathology and underlying mechanisms is not clear. We investigated the protective effects and underlying mechanisms of donepezil in AD-related triple transgenic (APP_Swe/PSEN1_M146V/MAPT_P301L) mouse model (3×Tg-AD). Mice (8-month old) were treated with donepezil (1.3 mg/kg) for 4 months and evaluated by behavioral tests for assessment of cognitive functions, and the hippocampal tissues were examined by protein analysis and quantitative proteomics. Behavioral tests showed that donepezil significantly improved the cognitive capabilities of 3×Tg-AD mice. The levels of soluble and insoluble amyloid beta proteins (Aβ_1-40 and Aβ_1-42) and senile plaques were reduced in the hippocampus. Golgi staining of the hippocampus showed that donepezil prevented dendritic spine loss in hippocampal neurons of 3×Tg-AD mice. Proteomic studies of the hippocampal tissues identified 3131 proteins with altered expression related to AD pathology, of which 262 could be significantly reversed with donepezil treatment. Bioinformatics with functional analysis and protein-protein interaction (PPI) network mapping showed that donepezil significantly elevated the protein levels of PINK 1, NFASC, MYLK2, and NRAS in the hippocampus, and modulated the biological pathways of axon guidance, mitophagy, mTOR, and MAPK signaling. The substantial upregulation of PINK 1 with donepezil was further verified by Western blotting. Donepezil exhibited neuroprotective effects via multiple mechanisms. In particular, PINK 1 is related to mitophagy and cellular protection from mitochondrial dysfunction, which might play important roles in AD pathogenesis and represent a potential therapeutic target.