Aminoguanidine treatment ameliorates inflammatory responses and memory impairment induced by amyloid-beta 25-35 injection in rats

Jiaohong pills attenuate neuroinflammation and amyloid-β protein-induced cognitive deficits by modulating the mitogen-activated protein kinase/nuclear factor kappa-B pathway

BACKGROUND

Jiaohong pills (JHP) consist of Pericarpium Zanthoxyli (PZ) and Radix Rehmanniae, two herbs that have been extensively investigated over many years due to their potential protective effects against cognitive decline and memory impairment. However, the precise mechanisms underlying the beneficial effects remain elusive. Here, research studies were conducted to investigate and validate the therapeutic effects of JHP on Alzheimer's disease.

METHODS

BV-2 cell inflammation was induced by lipopolysaccharide. AD mice were administered amyloid-β (Aβ). Behavioral experiments were used to evaluate learning and memory ability. The levels of nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-10 (IL-10) were detected using enzyme-linked immunosorbent assay (ELISA). The protein expressions of inducible nitric oxide synthase (iNOS) and the phosphorylation level of mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB) were detected using Western blot. Nissl staining was used to detect neuronal degeneration.

RESULTS

The results demonstrated that an alcoholic extract of PZ significantly decreased the levels of NO, IL-1β, TNF-α, and iNOS; increased the expression level of IL-10; and significantly decreased the phosphorylation levels of MAPK and NF-κB. These inhibitory effects were further confirmed in the AD mouse model. Meanwhile, JHP improved learning and memory function in AD mice, reduced neuronal damage, and enriched the Nissl bodies in the hippocampus. Moreover, IL-1β and TNF-α in the cortex were significantly downregulated after JHP administration, whereas IL-10 showed increased expression.

CONCLUSIONS

It was found that JHP reduced neuroinflammatory response in AD mice by targeting the MAPK/NF-κB signaling pathway.

The pathomimetic oAβ25–35 model of Alzheimer's disease: Potential for screening of new therapeutic agents

Alzheimer's disease (AD) is the most common form of dementia in the elderly, currently affecting more than 40 million people worldwide. The two main histopathological hallmarks of AD were identified in the 1980s: senile plaques (composed of aggregated amyloid-β (Aβ) peptides) and neurofibrillary tangles (composed of hyperphosphorylated tau protein). In the human brain, both Aβ and tau show aggregation into soluble and insoluble oligomers. Soluble oligomers of Aβ include their most predominant forms - Aβ_1-40 and Aβ_1-42 - as well as shorter peptides such as Aβ_25-35 or Aβ_25-35/40. Most animal models of AD have been developed using transgenesis, based on identified human mutations. However, these familial forms of AD represent less than 1% of AD cases. In this context, the idea emerged in the 1990s to directly inject the Aβ_25-35 fragment into the rodent brain to develop an acute model of AD that could mimic the disease's sporadic forms (99% of all cases). This review aims to: (1) summarize the biological activity of Aβ_25-35, focusing on its impact on the main structural and functional alterations observed in AD (cognitive deficits, APP misprocessing, tau system dysfunction, neuroinflammation, oxidative stress, cholinergic and glutamatergic alterations, HPA axis dysregulation, synaptic deficits and cell death); and (2) confirm the interest of this pathomimetic model in AD research, as it has helped identify and characterize many molecules (marketed, in clinical development, and in preclinical testing), and to the development of alternative approaches for AD prevention and therapy. Today, the Aβ_25-35 model appears as a first-intent choice model to rapidly screen the symptomatic or neuroprotective potencies of new compounds, chemical series, or innovative therapeutic strategies.

Antioxidant Compounds in the Treatment of Alzheimer's Disease: Natural, Hybrid, and Synthetic Products

Alzheimer's disease (AD) which is associated with cognitive dysfunction and memory lapse has become a health concern. Various targets and pathways have been involved in AD's progress, such as deficit of acetylcholine (ACh), oxidative stress, inflammation, β-amyloid (Aβ) deposits, and biometal dyshomeostasis. Multiple pieces of evidence indicate that stress oxidative participation in an early stage of AD and the generated ROS could enable neurodegenerative disease leading to neuronal cell death. Hence, antioxidant therapies are applied in treating AD as a beneficial strategy. This review refers to the development and use of antioxidant compounds based on natural products, hybrid designs, and synthetic compounds. The results of using these antioxidant compounds were discussed with the given examples, and future directions for the development of antioxidants were evaluated.

High-carbohydrate and fat diet consumption causes metabolic deterioration, neuronal damage, and loss of recognition memory in rats

The number of people diagnosed with metabolic syndrome (MetS) has increased dramatically to reach alarming proportions worldwide. The origin of MetS derives from bad eating habits and sedentary lifestyle. Most people consume foods high in carbohydrates and saturated fat. In recent years, it has been reported that alterations in insulin at the brain level could have an impact on the appearance of neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, dementia, depression, and other types of disorders that compromise brain function. These alterations have been associated with damage to the structure and function of neurons located in the reptilian and limbic systems, a decrease in dendritic arborization and an exacerbated inflammatory state that impaired learning and memory and increased in the state of stress and anxiety. Although the molecular mechanisms induced by MetS to cause neurodegeneration are not fully understood. The aim of this study is to know the effect of the intake of hypercaloric diets on the structure and function of neurons located in the frontal cortex, hypothalamus and hippocampus and its impact on behavior in rats with metabolic syndrome. In conclusion, the present study illustrated that chronic exposure to hypercaloric diets, with a high content of sugars and saturated fatty acids, induces a proinflammatory state and exacerbates oxidative stress in brain regions such as the hypothalamus, hippocampus, and frontal cortex, leading to dysfunction. metabolism, neuronal damage, and recognition memory loss.

Effect of cadmium administration on the antioxidant system and neuronal death in the hippocampus of rats

Cadmium (Cd) is a heavy metal classified as a carcinogen whose exposure could affect the function of the central nervous system. Studies suggest that Cd modifies neuronal morphology in the hippocampus and affects cognitive tasks. The oxidative stress pathway is proposed as a mechanism of toxicity. However, this mechanism is not precise yet. This study aimed to evaluate the effect of Cd administration on oxidative stress markers in the male rat's hippocampus. Male Wistar rats were divided into (1) control (drinking water) and (2) treatment with Cd (32.5 ppm of cadmium chloride (CdCl₂ ) in water). The Cd was administered for 2, 3, and 4 months. The results show that the oral administration of CdCl₂ increased the concentration of Cd in plasma and hippocampus, and this response is time-dependent on its administration. Likewise, it caused an increase in lipid peroxidation and nitrosative stress markers. Moreover, it increased reactive astrogliosis and antioxidant enzyme activity. Consequently, the progression of the oxidative response exacerbated neurodegeneration in hippocampal cells. Our results suggest that Cd exposure induces a severe oxidative response that contributes critically to hippocampal neurodegeneration. It is suggested that exposure to Cd increases the risk of developing neurological diseases, which contributes to a decrease in the quality of life of the human and the environment in which it lives.

Jiedu-Yizhi Formula Improves Cognitive Impairment in an Aβ 25-35-Induced Rat Model of Alzheimer's Disease by Inhibiting Pyroptosis

Jiedu-Yizhi formula (JDYZF) is prescribed for the treatment of Alzheimer's disease (AD) and was created by Jixue Ren, a master of traditional Chinese medicine, based on the "marrow deficiency and toxin damage" theory. In our clinic, this formula has been used for the treatment of AD for many years and has achieved good results. However, the mechanism by which JDYZF improves cognitive impairment has not been determined. In this study, we confirmed that orally administered JDYZF reversed the cognitive deficits in an Aβ _25-35-induced rat model, increased the number of neurons in the hippocampal CA1 area, improved their structure, decreased the deposition of β-amyloid (Aβ), reduced the expression of proteins related to the NLRP3/Caspase-1/GSDMD and LPS/Caspase-11/GSDMD pyroptosis pathways, and reduced the levels of interleukin 1β (IL-1β) and IL-18, thereby inhibiting the inflammatory response. In addition, JDYZF exerted no hepatotoxicity in rats. In short, these results provide scientific support for the clinical use of JDYZF to improve the cognitive function of patients with AD.

Targeting NLRP3 Inflammasome in Translational Treatment of Nervous System Diseases: An Update

Neuroinflammatory response is the immune response mechanism of the innate immune system of the central nervous system. Both primary and secondary injury can activate neuroinflammatory response. Among them, the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome plays a key role in the inflammatory response of the central system. Inflammasome is a type of pattern recognition receptor, a cytoplasmic polyprotein complex composed of members of the Nod-like receptor (NLR) family and members of the pyrin and HIN domain (PYHIN) family, which can be affected by a variety of pathogen-related molecular patterns or damage-related molecular patterns are activated. As one of the research hotspots in the field of medical research in recent years, there are increasing researches on immune function abnormalities in the onset of neurological diseases such as depression, AD, ischemic brain injury and cerebral infarction, the NLRP3 inflammasome causes the activated caspase-1 to cleave pre-interleukin-1β and pre-interleukin-18 into mature interleukin-1β and interleukin-18, in turn, a large number of inflammatory factors are produced, which participate in the occurrence and development of the above-mentioned diseases. Targeted inhibition of the activation of inflammasomes can reduce the inflammatory response, promote the survival of nerve cells, and achieve neuroprotective effects. This article reviews NLRP3 inflammasome's role in neurological diseases and related regulatory mechanisms, which providing references for future research in this field.

Beneficial effects of angiotensin converting enzyme inhibition on scopolamine-induced learning and memory impairment in rats, the roles of brain-derived neurotrophic factor, nitric oxide and neuroinflammation

The effect of the brain-derived neurotrophic factor (BDNF), cytokines, and renin angiotensin system (RAS) on memory function have been demonstrated. In this study, the effects of RAS inhibitor captopril (Capto) on hippocampal BDNF, interleukin -6 (IL-6), oxidative stress indicators, and nitric oxide (NO) in scopolamine (Sco)-induced memory impairment in rats were examined. The groups were (1) control, (2) Sco in which Sco was applied 30 min prior to the behavioral tests, and (3-5) Sco-Capto 10, 50, and 100 groups, where Capto (10, 50, or 100 mg/kg), were applied 2 weeks prior to the experiment, as well as 30 min prior to each Sco injection. The Morris Water Maze (MWM) test was conducted, and BDNF, IL-6, NO metabolites, malondialdehyde (MDA), thiol, superoxide dismutase (SOD), and catalase (CAT) were measured. Sco increased the delay and distance to the platform in the MWM test (P < .01 to P < .001), while shortening the time and distance in the target area (P < .01 to P < .001). Additionally, Sco increased IL-6, NO metabolites, and MDA, while decreasing BDNF, thiol, SOD, and CAT (P < .01 to P < .001). Although the Capto reduced the latency and distance traveled to the platform (P < .05 to P < .001), it elevated the time and distance traveled in the target area (P < .05 to P < .01). Furthermore, Capto improved BDNF, thiol, SOD, and CAT levels, and decreased IL-6, NO metabolites, and MDA (P < .05 to P < .001). RAS has a role in learning and memory impairment due to cholinergic system dysfunction. The possible mechanism(s) are including its effects on BDNF, neuro-inflammation and oxidative stress.

Aminoguanidine ameliorates ovariectomy-induced neuronal deficits in rats by inhibiting AGE-mediated Aβ production

Advanced glycation end products (AGEs) have been reported to cause neurodegeneration, senile plaque formation and spatial learning and memory deficits. There is much evidence describing the beneficial effects of aminoguanidine (AG) on the central nervous system; AG is able to inhibit the receptor for AGEs and beta-amyloid (Aβ) deposition in the brain, thus preventing cognitive decline and neurodegeneration. In this study, we investigated whether AG protects against ovariectomy-induced neuronal deficits and Aβ deposition in rats. Animals in the ovariectomy group (OVX) group, and those in the OVX+AG group were treated with AG (100 mg/kg/day) for 8 weeks. Learning and memory were evaluated using the electric Y maze. AGE and Aβ_1-40 biochemical assessments were performed using enzyme-linked immunosorbent assay (ELISA) kits. Furthermore, evaluations of brain amyloid precursor protein 695 (APP₆₉₅) mRNA expression by RT-PCR and AGE expression by immunohistochemistry were carried out. Ovariectomized rats exhibited memory impairment and Aβ production disorder with upregulated APP₆₉₅ mRNA and AGE expression levels. AG pretreatment relieved the ovariectomy-induced learning and memory disorder and significantly ameliorated the Aβ production disturbance and AGE generation. Additionally, pathological changes in morphology were also significantly recovered. Our data reveal that AG plays a potentially neuroprotective role against ovariectomy-induced learning and cognitive impairment and Aβ production disorder.

Advanced glycation end products (AGEs) have been reported to cause neurodegeneration, senile plaque formation and spatial learning and memory deficits. There is much evidence describing the beneficial effects of aminoguanidine (AG) on the central nervous system; AG is able to inhibit the receptor for AGEs and beta-amyloid (Aβ) deposition in the brain, thus preventing cognitive decline and neurodegeneration. In this study, we investigated whether AG protects against ovariectomy-induced neuronal deficits and Aβ deposition in rats. Animals in the ovariectomy group (OVX) group, and those in the OVX+AG group were treated with AG (100 mg/kg/day) for 8 weeks. Learning and memory were evaluated using the electric Y maze. AGE and Aβ_1-40 biochemical assessments were performed using enzyme-linked immunosorbent assay (ELISA) kits. Furthermore, evaluations of brain amyloid precursor protein 695 (APP₆₉₅) mRNA expression by RT-PCR and AGE expression by immunohistochemistry were carried out. Ovariectomized rats exhibited memory impairment and Aβ production disorder with upregulated APP₆₉₅ mRNA and AGE expression levels. AG pretreatment relieved the ovariectomy-induced learning and memory disorder and significantly ameliorated the Aβ production disturbance and AGE generation. Additionally, pathological changes in morphology were also significantly recovered. Our data reveal that AG plays a potentially neuroprotective role against ovariectomy-induced learning and cognitive impairment and Aβ production disorder.

Excitotoxicity as a Target Against Neurodegenerative Processes

The global burden of neurodegenerative diseases is alarmingly increasing in parallel to the aging of population. Although the molecular mechanisms leading to neurodegeneration are not completely understood, excitotoxicity, defined as the injury and death of neurons due to excessive or prolonged exposure to excitatory amino acids, has been shown to play a pivotal role. The increased release and/or decreased uptake of glutamate results in dysregulation of neuronal calcium homeostasis, leading to oxidative stress, mitochondrial dysfunctions, disturbances in protein turn-over and neuroinflammation. Despite the anti-excitotoxic drug memantine has shown modest beneficial effects in some patients with dementia, to date, there is no effective treatment capable of halting or curing neurodegenerative diseases such as Alzheimer's disease, Parkinson disease, Huntington's disease or amyotrophic lateral sclerosis. This has led to a growing body of research focusing on understanding the mechanisms associated with the excitotoxic insult and on uncovering potential therapeutic strategies targeting these mechanisms. In the present review, we examine the molecular mechanisms related to excitotoxic cell death. Moreover, we provide a comprehensive and updated state of the art of preclinical and clinical investigations targeting excitotoxic- related mechanisms in order to provide an effective treatment against neurodegeneration.

Puerariae Radix Prevents Anxiety and Cognitive Deficits in Mice Under Oligomeric Aβ-Induced Stress

To evaluate the therapeutic effects of Chinese herbal medicine (CHM) for Alzheimer's disease (AD), we evaluated five CHMs in oligomeric Aβ25-35-treated mouse primary hippocampal neuronal cultures. The aqueous extract from the root of Pueraria lobata (Puerariae Radix; PR) showed better neuroprotective effects than did the other four CHM aqueous extracts, including Gardenia jasminoides, Eleutherococcus senticosus, Rhodiola rosea, and Panax, in the primary culture treated with saline or oligomeric Aβ25-35. Furthermore, the neuroprotective effects of aqueous extract of PR were also better than its well-known active compound, puerarin, against the neurotoxicity of oligomeric Aβ25-35 in a primary culture. For in vivo experiments, C57BL/6J male mice that received direct infusion of soluble oligomeric Aβ25-35 into the bilateral hippocampal CA1 subregion were used as an alternative AD mouse model. The effects and molecular mechanisms of chronic systemic administration of PR aqueous extract were evaluated in the alternative AD model. PR aqueous extract prevented anxiety and cognitive impairment in mice associated with a decrease in the levels of Aβ deposition, tau protein phosphorylation, inflammation, loss of noradrenergic, and serotonergic neurons and an increase in the levels of synaptophysin and insulin degrading enzyme (IDE) against the toxicity of oligomeric Aβ25-35. Furthermore, no obvious damage to the liver and kidney was detected after chronic systemic administration of PR aqueous extract. Therefore, using PR could be a safer, more effective therapeutic strategy than using its active compound puerarin to prevent both cognitive and noncognitive dysfunction and related pathological features of AD.

The Acute Activation of the CB1 Receptor in the Hippocampus Decreases Neurotoxicity and Prevents Spatial Memory Impairment in Rats Lesioned with β-Amyloid 25-35

Given their anti-inflammatory properties, cannabinoids have been shown to be neuroprotective agents and to reduce excitotoxicity, through the activation of the Cannabinoid receptor type 1 (CB1r). These properties have led to CB1r being proposed as pharmacological targets for the treatment of various neurodegenerative diseases. Amyloid-β 25-35 (Aβ_25-35) induces the expression of inducible nitric oxide synthase (iNOS) and increases nitric oxide (NO●) levels. It has been observed that increased NO● concentrations trigger biochemical pathways that contribute to neuronal death and cognitive damage. This study aimed to evaluate the neuroprotective effect of an acute activation of CB1r on spatial memory and its impact on iNOS protein expression, NO● levels, gliosis and the neurodegenerative process induced by the injection of Aβ_(25-35) into the CA1 subfield of the hippocampus. ACEA [1 μM/1 μL] and Aβ_(25-35) [100 μM/1 μL] and their respective vehicle groups were injected into the CA1 subfield of the hippocampus. The animals were tested for spatial learning and memory in the eight-arm radial maze, with the results revealing that the administration of ACEA plus Aβ_(25-35) improves learning and memory processes, in contrast with the Aβ_(25-35) group. Moreover, ACEA plus Aβ_(25-35) prevented both the increase in iNOS protein and NO● levels and the reactive gliosis induced by Aβ_(25-35). Importantly, neurodegeneration was significantly reduced by the administration of ACEA plus Aβ_(25-35) in the CA1 subfield of the hippocampus. The data obtained in the present research suggest that the acute early activation of CB1r is crucial for neuroprotection.

Epicatechin Reduces Spatial Memory Deficit Caused by Amyloid-β25⁻35 Toxicity Modifying the Heat Shock Proteins in the CA1 Region in the Hippocampus of Rats

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by dementia and the aggregation of the amyloid beta peptide (Aβ). Aβ_25-35 is the most neurotoxic sequence, whose mechanism is associated with the neuronal death in the Cornu Ammonis 1 (CA1) region of the hippocampus (Hp) and cognitive damage. Likewise, there are mechanisms of neuronal survival regulated by heat shock proteins (HSPs). Studies indicate that pharmacological treatment with flavonoids reduces the prevalence of AD, particularly epicatechin (EC), which shows better antioxidant activity. The aim of this work was to evaluate the effect of EC on neurotoxicity that causes Aβ_25-35 at the level of spatial memory as well as the relationship with immunoreactivity of HSPs in the CA1 region of the Hp of rats. Our results show that EC treatment reduces the deterioration of spatial memory induced by the Aβ_25-35, in addition to reducing oxidative stress and inflammation in the Hp of the animals treated with EC + Aβ_25-35. Likewise, the immunoreactivity to HSP-60, -70, and -90 is lower in the EC + Aβ_25-35 group compared to the Aβ_25-35 group, which coincides with a decrease of dead neurons in the CA1 region of the Hp. Our results suggest that EC reduces the neurotoxicity induced by Aβ_25-35, as well as the HSP-60, -70, and -90 immunoreactivity and neuronal death in the CA1 region of the Hp of rats injected with Aβ_25-35, which favors an improvement in the function of spatial memory.

Protective effect of aminoguanidine against lipopolysaccharide-induced hepatotoxicity and liver dysfunction in rat

Lipopolysaccharide (LPS) as the major component of the outer membrane of Gram-negative bacteria activates macrophages to produce a high level of pro-inflammatory cytokines which is considered as a cause of liver dysfunction. Overproduction of nitric oxide (NO) has been suggested to have a role in hepatic injury. The aim of the present study was to explore the protective effects of aminoguanidine (AG) as inducible nitric oxide synthase (iNOS) inhibitor against LPS -induced liver dysfunction in rat. The animals were divided into five groups: (1) control (2) LPS (3) LPS-AG50, (4) LPS-AG100 and (5) LPS-AG150. LPS (1 mg/kg) was injected for 5 weeks and AG (50, 100 and 150 mg/kg) was administered 30 min before LPS. Drugs were injected intraperitoneally. LPS induced liver dysfunction presented by increasing the serum level of alkaline phosphatase (ALK-P), alanine aminotransferase (ALT), aspartate aminotransferase (AST). Pretreatment with AG restored harmful effects of LPS on liver function. In addition, LPS resulted in hepatotoxicity, accompanied by enhancing the level of interleukin (IL)-6, malondialdehyde (MDA) and nitric oxide (NO) metabolites and decreasing the content of total thiol groups and superoxide dismutase (SOD) and catalase (CAT) activity. Injection of AG before LPS attenuated LPS-induced hepatotoxicity through decreasing the level of IL-6, MDA and NO metabolites and increasing total thiols and SOD and CAT activity. Considering the protective effect of AG which was seen in the present study, it seems that increased levels of NO due to activation of iNOS has a role in LPS-induced hepatic injury.

Altered Nup153 Expression Impairs the Function of Cultured Hippocampal Neural Stem Cells Isolated from a Mouse Model of Alzheimer's Disease

Impairment of adult hippocampal neurogenesis is an early event in Alzheimer's disease (AD), playing a crucial role in cognitive dysfunction associated with this pathology. However, the mechanisms underlying defective neurogenesis in AD are still unclear. Recently, the nucleoporin Nup153 has been described as a new epigenetic determinant of adult neural stem cell (NSC) maintenance and fate. Here we investigated whether Nup153 dysfunction could affect the plasticity of NSCs in AD. Nup153 expression was strongly reduced in AD-NSCs, as well as its interaction with the transcription factor Sox2, a master regulator of NSC stemness and their neuronal differentiation. Similar Nup153 reduction was also observed in WT-NSCs treated with amyloid-β (Aβ) or stimulated with a nitric oxide donor. Accordingly, AD-NSCs treated with either a γ-secretase inhibitor or antioxidant compounds showed higher Nup153 levels suggesting that both nitrosative stress and Aβ accumulation affect Nup153 expression. Of note, restoration of Nup153 levels in AD-NSCs promoted their proliferation, as assessed by BrdU incorporation, neurosphere assay, and stemness gene expression analysis. Nup153 overexpression also recovered AD-NSC response to differentiation, increasing the expression of pro-neuronal genes, the percentage of cells positive for neuronal markers, and the acquisition of a more mature neuronal phenotype. Electrophysiological recordings revealed that neurons differentiated from Nup153-transfected AD-NSCs displayed higher Na⁺ current density, comparable to those deriving from WT-NSCs. Our data uncover a novel role for Nup153 in NSCs from animal model of AD and point to Nup153 as potential target to restore physiological NSC behavior and fate in neurodegenerative diseases.

Aminoguanidine reverses cognitive deficits and activation of cAMP/CREB/BDNF pathway in mouse hippocampus after traumatic brain injury (TBI)

PRIMARY OBJECTIVE

We aim to study the effects of chronic aminoguanidine (AG) administration on learning and memory impairment after TBI and explore the potential mechanism involved in this process.

RESEARCH DESIGN

Male C57BL/6J mice were divided into 6 groups: Control, TBI + Veh, TBI+ AG (50, 100, 200 and 400 mg/kg, i.p.).

METHODS AND PROCEDURES

Then, we measured cyclicadenosine 3', 5'-monophosphate (cAMP) content, phosphorylated form of cAMP-response element binding protein (p-CREB) level, iNOS, brain-derived neurotrophic factor (BDNF) and postsynaptic density-93/95 (PSD-93/95) expression in hippocampus. The learning and memory abilities were assessed using Morris water maze and step-down test.

MAIN OUTCOMES AND RESULTS

The results demonstrate that TBI induced down-regulation of BDNF, loss of PSD-93/95, learning and memory deficits with down-regulation of cAMP content and p-CREB/CREB ratio. Administration of AG (200 and 400 mg/kg) reversed TBI induced down-regulation of BDNF and PSD-93/95, up-regulated the cAMP content and p-CREB/CREB ratio, which resulted in improvement of learning and memory ability.

CONCLUSIONS

We suspect that AG (200 and 400 mg/kg) might reverse TBI-induced selective loss of postsynaptic proteins and learning and memory deficits with the activation of cAMP/CREB/BDNF signalling pathway.

The effects of aminoguanidine on hippocampal cytokines, amyloid beta, brain-derived neurotrophic factor, memory and oxidative stress status in chronically lipopolysaccharide-treated rats

INTRODUCTION

In the present study, the effects of aminoguanidine (AMG) on hippocampal cytokines, amyloid beta (Aβ), brain-derived neurotrophic factor, oxidative stress status and memory in chronically lipopolysaccharide (LPS) treated rats were investigated.

METHODS

The rats were divided into five groups and were treated: (1) Control (Saline), (2) LPS (1 mg/kg), (3-5) LPS- AMG50, LPS-AMG100, and LPS-AMG150 (AMG 50, 100 and 150 mg/kg 30 min before LPS injection). The treatment started five weeks prior to the behavioral experiments and continued during the behavioral tests (LPS injection two hours before each behavioral evaluation). Finally, the tissue was removed for biochemical measurements.

RESULTS

The escape latency in Morris water maze test and the latency to enter the dark compartment in passive avoidance test in LPS group were significantly greater than the control group (P < 0.001), while, in LPS-AMG 100 and LPS-AMG150 groups they were less than LPS group (P < 0.001). Malondialdehyde (MDA), NO metabolites of hippocampal and cortical tissues and interleukin-6 (IL-6), Aβ and tumor necrosis factor-α (TNFα) concentration in the hippocampus of LPS group were higher than control group (P < 0.001-P < 0.05). However, in LPS-AMG 100 and LPS-AMG150 group they were lower than LPS group (P < 0.001-P < 0.05). The thiol content and the activities of catalase (CAT) and superoxide dismutase (SOD) in both cortical and hippocampal tissues of LPS group were reduced compared to the control group (P < 0.001-P < 0.05). These factors enhanced in LPS-AMG 100 and LPS-AMG150 groups compared to LPS (P < 0.001-P < 0.05). The hippocampal content of brain-derived neurotrophic factor (BDNF) in LPS group was significantly lower compared to the control group (P < 0.001). All treated groups had higher BDNF content in comparison to LPS group (P < 0.01-P < 0.001).

CONCLUSION

The findings indicated that the protective effects of AMG against LPS-induced memory were accompanied by decreasing of inflammatory cytokines, Aβ, oxidative stress and increasing of anti-inflammatory mediators and BDNF.

Metabolic Syndrome Exacerbates the Recognition Memory Impairment and Oxidative-Inflammatory Response in Rats with an Intrahippocampal Injection of Amyloid Beta 1-42

An important worldwide health problem as the result of current lifestyle is metabolic syndrome (MS). It has been shown that MS induced by a high-calorie diet (HCD) in rats produces cognitive deterioration in the novel object recognition test (NORt) and decreases synaptic connections and dendritic order in the hippocampus and temporal cortex. However, it is unknown whether MS induced by an HCD participates in the cognitive process observed with the injection of Aβ_1–42 into the hippocampus of rats as a model of Alzheimer disease (AD). The induction of MS in rats produces a deterioration in NORt; however, rats with MS injected with Aβ_1–42 show a major deterioration in the cognitive process. This event could be explained by the increment in the oxidative stress in both cases studied (MS and Aβ_1–42): together, the hippocampus and temporal cortex produce an enhancer effect. In the same way, we observed an increment in interleukin-1β, TNF-α, and GFAP, indicative of exacerbated inflammatory processes by the combination of MS and Aβ_1–42. We can conclude that MS might play a key role in the apparition and development of cognitive disorders, including AD. We propose that metabolic theory is important to explain the apparition of cognitive diseases.

Preventive effects of taurine against d-galactose-induced cognitive dysfunction and brain damage

Oxidative stress arising from life processes or environmental influences and its resultant cellular dysfunctions are major causes of neurodegenerative disorders. The objectives of this study were to investigate whether taurine (Tau) can prevent d-galactose-induced cognitive dysfunction and brain oxidative damage. Mice given with Tau supplementation (100 and 400 mg per kg BW per day) spent shorter (p < 0.05) time in searching target in d-galactose (100 mg per kg BW per day) treated mice in a water maze reference memory experiment. Moreover, Tau supplementation extended (p < 0.05) the searching period around the target quadrant in the probe test of the water maze, and neuronal degeneration and nucleus shrinkage in the hippocampus dentate gyrus area of d-galactose treated mice were observed to be attenuated. Tau also downregulated (p < 0.05) expression of the glial fibrillary acidic protein (Gfap) and of the cluster of differentiation marker Cd11b; meanwhile, it strengthened (p < 0.05) antioxidant capacity and lowered (p < 0.05) the accumulation of advanced glycation end-products (AGEs) in the brain. Therefore, Tau could be effective to ameliorate oxidative damage and inflammation in the brain, and apoptosis of brain cells, which further lessen the cognitive dysfunction.

Inducible nitric oxide inhibitor aminoguanidine, ameliorated oxidative stress, interleukin-6 concentration and improved brain-derived neurotrophic factor in the brain tissues of neonates born from titanium dioxide nanoparticles exposed rats

Introduction: An interaction between oxidative stress, neuroinflammation, and nitric oxide (NO) has been suggested to have a role neurotoxicity. The aim of current research was to investigate the effect of aminoguanidine (AG) as an inducible NO synthase (iNOS) inhibitor, on brain-derived neurotrophic factor (BDNF), oxidative stress, and interleukin-6 (IL-6) concentrations in the brain tissues of neonates born from the rats exposed to titanium dioxide nanoparticles (TiO2 NPs) during gestation. Methods: The pregnant rats were grouped into three and received: (1) saline, (2) TiO2 (200 mg/kg, gavage), and (3) TiO2-AG [200 mg/kg intraperitoneal (IP)]. The treatment was started since the second gestation day up to the delivery time. The neonates born from the rats were deeply anesthetized, sacrificed, and the brains were collected for biochemical evaluations. Results: The neonates born from the rats exposed to TiO₂ showed a lower BDNF (p < .001) but a higher IL-6 (p < .01) concentrations in their hippocampal tissue. TiO₂ exposure also increased malondialdehyde (MDA) (p < .001) and NO metabolites (p < .001), while diminished thiol (p < .001), superoxide (SOD) (p < .001), and catalase (CAT) (p < .001) in all hippocampal, cortical, and cerebellar tissues. Administration of AG improved BDNF (p < .01) but attenuated IL-6 (p < .01) concentrations in the hippocampal tissue. AG also decreased MDA (p < .001) and NO metabolites (p < .01-p < .001), while increased thiol (p < .01-p < .001), SOD (p < .001), and CAT (p < .05-p < .001) in all cerebellar, hippocampal, cortical, and tissues. Conclusion: The results of the current research revealed that iNOS inhibitor AG, ameliorated oxidative stress, IL-6 concentration, and improved BDNF in the brain tissues of neonates born from TiO₂ NPs exposed rats.

Magnesium Ions Inhibit the Expression of Tumor Necrosis Factor α and the Activity of γ-Secretase in a β-Amyloid Protein-Dependent Mechanism in APP/PS1 Transgenic Mice

Alzheimer’s disease (AD) is a neurodegenerative disease characterized by cognitive impairment. The neuropathological features of AD are the aggregation of extracellular amyloid β-protein (Aβ) and tau phosphorylation. Recently, AD was found to be associated with magnesium ion (Mg²⁺) deficit and tumor necrosis factor-alpha (TNF-α) elevation in the serum or brains of AD patients. To study the relationship between Mg²⁺ and TNF-α, we used human- or mouse-derived glial and neuronal cell lines or APP/PS1 transgenic (Tg) mice as in vitro and in vivo experimental models, respectively. Our data demonstrates that magnesium-L-threonate (MgT) can decrease the expression of TNF-α by restoring the levels of Mg²⁺ in glial cells. In addition, PI3-K/AKT and NF-κB signals play critical roles in mediating the effects of Mg²⁺ on suppressing the expression of TNF-α. In neurons, Mg²⁺ elevation showed similar suppressive effects on the expression of presenilin enhancer 2 (PEN2) and nicastrin (NCT) through a PI3-K/AKT and NF-κB-dependent mechanism. As the major components of γ-secretase, overexpression of presenilin 1 (PS1), PEN2 and NCT potentially promote the synthesis of Aβ, which in turn activates TNF-α in glial cells. Reciprocally, TNF-α stimulates the expression of PEN2 and NCT in neurons. The crosstalk between TNF-α and Aβ in glial cells and neurons could ultimately aggravate the development and progression of AD.

Neuroinflammation induced by amyloid β25-35 modifies mucin-type O-glycosylation in the rat's hippocampus

Amyloid-β (Aβ) plays a relevant role in the neurodegenerative process of Alzheimer's disease (AD). The 25-35 peptide of amyloid-β (Aβ25-35) induces the inflammatory response in brain experimental models. Mucin-type O-glycosylation has been associated with inflammation of brain tissues in AD, thus in this work, we aimed at identifying changes in the glycosylation profile generated by the injection of Aβ25-35 into the CA1 of the hippocampus of rats, using histochemistry with lectins. Our results indicate that 100μM Aβ25-35 induce increased recognition of the Amaranthus leucocarpus lectin (ALL) (specific for Galβ1,3-GalNAcα1,0-Ser/Thr); whereas concanavalin A (Con A) (specific for α-Man) showed no differences among treated and control groups of rats. Jacalin and peanut agglutinin (Galβ1,3GalNAcα1,0-Ser/Thr) showed no recognition of brain cells of control or treated rats. After 6-h treatment of the tissue with trypsin or with 200mM GalNAc, the interaction with ALL was inhibited. Immunohistochemistry showed positive anti-NeuN and ALL-recognition of neurons; however, anti-GFAP and anti-CD11b showed no co-localization with ALL. The ALL+ neurons revealed the presence of cytochrome C in the cytosol and active caspase 3 in the cytosol and nucleus. Administration of the interleukin-1 receptor antagonist (IL-1RA) to Aβ25-35-treated rats diminished neuroinflammation and ALL recognition. These results suggest a close relationship among over-expression of mucin-type O-glycosylation, the neuroinflammatory process, and neuronal death.

Ketamine and aminoguanidine differentially affect Bdnf and Mtor gene expression in the prefrontal cortex of adult male rats

The rapid and sustained antidepressant properties of ketamine provide evidence of the importance of the glutamatergic system in the neurobiology of depression. The antidepressant-like effects of ketamine are dependent on brain-derived neurotrophic factor (BDNF) and mammalian target of rapamycin (mTOR) in limbic brain areas. The nitrergic system is closely related to the glutamatergic system and generates antidepressant-like effects when blocked. The aim of this study was to investigate whether the behavioural effects induced by the inhibition of nitric oxide (NO) synthesis by aminoguanidine or N-methyl-D-aspartate (NMDA) receptor blockade by ketamine would affect the gene expression of Bdnf and Mtor in the ventromedial prefrontal cortex in rats. The effects of ketamine or aminoguanidine were investigated in Sprague-Dawley (SD) rats, the Flinders Sensitive Line (FSL), a genetic rat model of depression, and their controls, the Flinders Resistant Line (FRL) rats. In the studies, the three protocols evaluated to which the animals/rats were exposed were: (1) pre-test and test sessions of forced swim test (FST), (2) pre-test session of FST alone, or (3) not exposed to the FST. Ketamine and aminoguanidine both induce antidepressant-like effects in SD and FSL rats. Quantitative real-time polymerase chain reaction analyses in SD rats demonstrated that none of the treatments can change the Bdnf or Mtor gene expression, but in FSL rats the treatment with ketamine increased only Bdnf gene expression. The data obtained strengthens the role of NMDA antagonists and NO inhibitors as potential antidepressant drugs, albeit with different effects on Bdnf gene expression.

l-arginine modulates inflammation and muscle regulatory genes after a single session of resistance exercise in rats

We investigated the skeletal muscle adaptation to l-arginine supplementation prior to a single session of resistance exercise (RE) during the early phase of muscle repair. Wistar rats were randomly assigned into non-exercised (Control), RE plus vehicle (RE); RE plus l-arginine (RE+L-arg) and RE plus aminoguanidine (RE+AG) groups. Animals received four doses of either vehicle (0.9% NaCl), l-arg (1 g/b.w.), or AG (iNOS inhibitor) (50 mg/b.w.). The animals performed a single RE session until the concentric failure (ladder climbing; 80% overload) and the skeletal muscles were harvested at 0, 8, 24, and 48 hours post-RE. The RE resulted in increased neutrophil infiltrate (24 hours post-RE) (3621 vs 11852; P<.0001) associated with enhanced TNF-α (819.49 vs 357.02; P<.005) and IL-6 (3.84 vs 1.08; P<.0001). Prior, l-arginine supplementation attenuates neutrophil infiltration (5622; P<.0001), and also TNF-α (506.01; P<.05) and IL-6 (2.51, P<.05) levels. AG pretreatment mediated an inhibition of iNOS levels similar to levels found in RE group. RE animals displayed increased of atrogin-1 (1.9 fold) and MuRF-1 (3.2 fold) mRNA levels, reversed by l-arg supplementation [atrogin-1 (0.6 fold; P<.001); MuRF-1 (0.8-fold; P<.001)] at 24 hours post-RE. MyoD up-regulated levels were restricted to l-arg treated animals at 24 hours (2.8 vs 1.5 fold; P<.005) and 48 hours post-RE (2.4 vs 1.1 fold; P<.001). AG pretreatment reversed these processes at 24 hours [atrogin-1 (2.1 fold; P<.0001); MuRF-1 (2.5 fold; P<.0001); MyoD (1.4 fold)]. l-arginine supplementation seems to attenuate the resolution of RE-induced muscle inflammation and up-regulates MyoD expression during the early phase of muscle repair.

Prostaglandin I2 is responsible for ameliorating prostaglandin E2 stress in stimulating the expression of tumor necrosis factor α in a β-amyloid protein -dependent mechanism

Cyclooxygenase-2 (COX-2) has been found to be induced during the early stage of Alzheimer's disease (AD). Using mouse-derived astrocyte and APP/PS1 transgenic (Tg) mice as model systems, we firstly elucidated the mechanisms underlying COX-2 metabolic production including prostaglandin (PG)E₂- and PGI₂-mediated tumor necrosis factor α (TNF-α) regulation. Specifically, PGE₂ accumulation in astrocyte activated the p38 and JNK/c-Jun signaling pathways via phosphorylation, resulting in TNF-α expression. In contrast, the administration of PGI₂ attenuated the effects of PGE₂ in stimulating the production of TNF-α by inhibiting the activity of TNF-α promoter and the binding activity of AP1 on the promoter of TNF-α. Moreover, our data also showed that not only Aβ_1-42 oligomers but also Aβ_1-42 fibrils have the ability to involve in mediating the antagonistic effects of PGE₂ and PGI₂ on regulating the expression of TNF-α via a p38- and JNK/c-Jun-dependent, AP1-transactivating mechanism. Reciprocally, the production of TNF-α finally accelerated the deposition of β-amyloid protein (Aβ)_1-42 in β-amyloid plaques (APs), which contribute to the cognitive decline of AD.

Possible involvement of CREB/BDNF signaling pathway in neuroprotective effects of topiramate against methylphenidate induced apoptosis, oxidative stress and inflammation in isolated hippocampus of rats: Molecular, biochemical and histological evidences

Chronic abuse of methylphenidate (MPH) can cause serious neurotoxicity. The neuroprotective effects of topiramate (TPM) were approved, but its putative mechanism remains unclear. In current study the role of CREB/BDNF signaling pathway in TPM protection against methylphenidate-induced neurotoxicity in rat hippocampus was evaluated. 60 adult male rats were divided randomly into six groups. Groups received MPH (10mg/kg) only and concurrently with TPM (50mg/kg and 100mg/kg) and TPM (50 and 100mg/kg) only for 14 days. Open field test (OFT) was used to investigate motor activity. Some biomarkers of apoptotic, anti-apoptotic, oxidative, antioxidant and inflammatory factors were also measured in hippocampus. Expression of total (inactive) and phosphorylated (active) CREB and BDNF were also measured in gene and protein levels in dentate gyrus (DG) and CA1 areas of hippocampus. MPH caused significant decreases in motor activity in OFT while TPM (50 and 100mg/kg) inhibited MPH-induced decreases in motor activity. On the other hand, MPH caused remarkable increases in Bax protein level, lipid peroxidation, catalase activity, IL-1β and TNF-α levels in hippocampal tissue. MPH also caused significant decreases of superoxide dismutase, activity and also decreased CREB, in both forms, BDNF and Bcl-2 protein levels. TPM, by the mentioned doses, attenuated these effects and increased superoxide dismutase, glutathione peroxidase and glutathione reductase activities and also increased CREB, in both forms, BDNF and Bcl-2 protein levels and inhibited MPH induced increase in Bax protein level, lipid peroxidation, catalase activity, IL-1β and TNF-α levels. TPM also inhibited MPH induced decreases in cell number and changes in cell shapes in DG and CA1 areas. TPM can probably act as a neuroprotective agent against MPH induced neurotoxicity and this might have been mediated by CREB/BDNF signaling pathway.

Redox-based therapeutics in neurodegenerative disease

This review describes recent developments in the search for effective therapeutic agents that target redox homeostasis in neurodegenerative disease. The disruption to thiol redox homeostasis in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and multiple sclerosis is discussed, together with the experimental strategies that are aimed at preventing, or at least minimizing, oxidative damage in these diseases. Particular attention is given to the potential of increasing antioxidant capacity by targeting the Nrf2 pathway, the development of inhibitors of NADPH oxidases that are likely candidates for clinical use, together with strategies to reduce nitrosative stress and mitochondrial dysfunction. We describe the shortcomings of compounds that hinder their progression to the clinic and evaluate likely avenues for future research.

LINKED ARTICLES

This article is part of a themed section on Redox Biology and Oxidative Stress in Health and Disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.12/issuetoc.

An Extract from Shrimp Processing By-Products Protects SH-SY5Y Cells from Neurotoxicity Induced by Aβ25-35

Increased evidence suggests that marine unsaturated fatty acids (FAs) can protect neurons from amyloid-β (Aβ)-induced neurodegeneration. Nuclear magnetic resonance (NMR), high performance liquid chromatography (HPLC) and gas chromatography (GC) assays showed that the acetone extract 4-2A obtained from shrimp Pandalus borealis industry processing wastes contained 67.19% monounsaturated FAs and 16.84% polyunsaturated FAs. The present study evaluated the anti-oxidative and anti-inflammatory effects of 4-2A in Aβ_25–35-insulted differentiated SH-SY5Y cells. Cell viability and cytotoxicity were measured by using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Quantitative PCR and Western blotting were used to study the expression of neurotrophins, pro-inflammatory cytokines and apoptosis-related genes. Administration of 20 μM Aβ_25–35 significantly reduced SH-SY5Y cell viability, the expression of nerve growth factor (NGF) and its tyrosine kinase TrkA receptor, as well as the level of glutathione, while increased reactive oxygen species (ROS), nitric oxide, tumor necrosis factor (TNF)-α, brain derived neurotrophic factor (BDNF) and its TrkB receptor. Aβ_25–35 also increased the Bax/Bcl-2 ratio and Caspase-3 expression. Treatment with 4-2A significantly attenuated the Aβ_25–35-induced changes in cell viability, ROS, GSH, NGF, TrkA, TNF-α, the Bax/Bcl-2 ratio and Caspase-3, except for nitric oxide, BDNF and TrKB. In conclusion, 4-2A effectively protected SH-SY5Y cells against Aβ-induced neuronal apoptosis/death by suppressing inflammation and oxidative stress and up-regulating NGF and TrKA expression.

Metabolic syndrome causes recognition impairments and reduced hippocampal neuronal plasticity in rats

Metabolic syndrome (MS) is a serious public health problem, which can promote neuronal alterations in cognitive regions related to learning and memory processes, such as the hippocampus. However, up to now there has been information of a regional segregation of this damage. In this study, we evaluate the MS effect on the neuronal morphology of the hippocampus. Our results demonstrate that 90days of a high-calorie diet alters the metabolic energy markers causing the MS and causes memory impairments, evaluated by the recognition of novel objects test (NORT). In addition, MS animals showed significant differences in dendritic order, total dendritic length and density of dendritic spines in CA1, CA3 and the dentate gyrus (DG) of the hippocampal area, compared with rats fed with a normocaloric diet (vehicle group). Furthermore, the immunoreactivity to synaptophysin (Syp) decreased in the hippocampus of the MS animals compared to the vehicle group. These results indicate that metabolic alterations induced by the MS affect hippocampal plasticity and hippocampal dependent memory processes.

Antioxidative stress effect of epicatechin and catechin induced by Aβ25-35 in rats and use of the electrostatic potential and the Fukui function as a tool to elucidate specific sites of interaction

Alzheimer's disease (AD) is a neurodegenerative disorder caused by the aggregation of the amyloid-beta peptide (Aβ) in senile plaques and cerebral vasculature. The Aβ_25-35 fraction has shown the most toxicity; its neurotoxic mechanisms are associated with the generation of oxidative stress and reactive astrogliosis that induce neuronal death and memory impairment. Studies indicate that pharmacological treatment with flavonoids reduces the rate of AD, in particular, it has been shown that antioxidants are compounds that could interact with this peptide due to their antioxidant proprieties. In this study, experimental and computational tools were used to calculate the molecular electrostatic potential and the Fukui function with the Gaussian 09 computational program, to predict the most reactive parts of these molecules and make the complex between Aβ_25-35 and two flavonoids (catechin and epicatechin) in the absolute gas-phase, where a possible interaction between them was observed. This is important for understanding the Aβ_25-35-Flavonoid (A-F) interaction as a therapeutic strategy to inhibit the neurotoxic effects that this peptide causes in AD, which currently is still considered an ambiguous process.

Effects of the inducible nitric oxide synthase inhibitor aminoguanidine in two different rat models of schizophrenia

Several lines evidence indicate that the non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist ketamine and the mixed dopamine (DA) D1/D2 receptor agonist apomorphine induce schizophrenia-like symptoms in rodents, including memory impairments and social withdrawal. Nitric oxide (NO) has been proposed to act as an intracellular messenger in the brain and its overproduction is associated with schizophrenia. The current study was designed to investigate the ability of the inducible NO synthase (iNOS) inhibitor aminoguanidine (AG) to counteract schizophrenia-like behavioural deficits produced by ketamine and apomorphine in rats. The efficacy of AG to antagonize extinction of recognition memory, ketamine and apomorphine-induced recognition memory impairments was tested utilizing the novel object recognition task (NORT). Further, the efficacy of AG to attenuate ketamine-induced social withdrawal was examined in the social interaction test. AG (25 and 50mg/kg) antagonized extinction of recognition memory and reversed ketamine (3mg/kg) and apomorphine (1mg/kg)-induced recognition memory deficits. In contrast, AG (50 and 100mg/kg) did not counteract the ketamine (8mg/kg)-induced social isolation. The present data show that the iNOS inhibitor AG counteracted extinction of recognition memory and reversed recognition memory deficits produced by dysfunction of the glutamatergic and the dopaminergic (DAergic) system in rats. Therefore, AG may be efficacious in attenuating memory impairments often observed in schizophrenia patients.

Energy Drink Administration in Combination with Alcohol Causes an Inflammatory Response and Oxidative Stress in the Hippocampus and Temporal Cortex of Rats

Energy drinks (EDs) are often consumed in combination with alcohol because they reduce the depressant effects of alcohol. However, different researches suggest that chronic use of these psychoactive substances in combination with alcohol can trigger an oxidative and inflammatory response. These processes are regulated by both a reactive astrogliosis and an increase of proinflammatory cytokines such as IL-1β, TNF-α, and iNOS, causing cell death (apoptosis) at the central and peripheral nervous systems. Currently, mechanisms of toxicity caused by mixing alcohol and ED in the brain are not well known. In this study, we evaluated the effect of chronic alcohol consumption in combination with ED on inflammatory response and oxidative stress in the temporal cortex (TCx) and hippocampus (Hp) of adult rats (90 days old). Our results demonstrated that consuming a mixture of alcohol and ED for 60 days induced an increase in reactive gliosis, IL-1β, TNF-α, iNOS, reactive oxygen species, lipid peroxidation, and nitric oxide, in the TCx and Hp. We also found immunoreactivity to caspase-3 and a decrease of synaptophysin in the same brain regions. The results suggested that chronic consumption of alcohol in combination with ED causes an inflammatory response and oxidative stress, which induced cell death via apoptosis in the TCx and Hp of the adult rats.

Administration of NaHS Attenuates Footshock-Induced Pathologies and Emotional and Cognitive Dysfunction in Triple Transgenic Alzheimer's Mice

Alzheimer's disease (AD) is characterized by progressive cognitive decline and neuropsychiatric symptoms. Increasing evidence indicates that environmental risk factors in young adults may accelerate cognitive loss in AD and that Hydrogen Sulfide (H2S) may represent an innovative treatment to slow the progression of AD. Therefore, the aim of this study was to evaluate the effects of NaHS, an H2S donor, in a triple transgenic AD mouse model (3×Tg-AD) under footshock with situational reminders (SRs). Inescapable footshock with SRs induced anxiety and cognitive dysfunction as well as a decrease in the levels of plasma H2S and GSH and an increase in IL-6 levels in 3×Tg-AD mice. Under footshock with SR stimulus, amyloid deposition, tau protein hyperphosphorylation, and microgliosis were highly increased in the stress-responsive brain structures, including the hippocampus and amygdala, of the AD mice. Oxidative stress, inflammatory response, and β-site APP cleaving enzyme 1 (BACE1) levels were also increased, and the level of inactivated glycogen synthase kinase-3β (GSK3β) (pSer9) was decreased in the hippocampi of AD mice subjected to footshock with SRs. Furthermore, the numbers of cholinergic neurons in the medial septum/diagonal band of Broca (MS/DB) and noradrenergic neurons in the locus coeruleus (LC) were also decreased in the 3×Tg-AD mice under footshock with SRs. These biochemical hallmarks and pathological presentations were all alleviated by the semi-acute administration of NaHS in the AD mice. Together, these findings suggest that footshock with SRs induces the impairment of spatial cognition and emotion, which involve pathological changes in the peripheral and central systems, including the hippocampus, MS/DB, LC, and BLA, and that the administration of NaHS may be a candidate strategy to ameliorate the progression of neurodegeneration.

Association of Neuroprotective Effect of Di-O-Demethylcurcumin on Aβ25-35-Induced Neurotoxicity with Suppression of NF-κB and Activation of Nrf2

Amyloid-β peptides (Aβ), a major component of senile plaques, play an important role in the development and progression of Alzheimer's disease. Several lines of evidence have demonstrated that Aβ-induced neuronal death is mediated by oxidative stress. The present study aimed to evaluate the potential involvement of di-O-demethylcurcumin, an analog of curcuminoid, on Aβ-induced neurotoxicity in culture neuroblastoma cells (SK-N-SH cells) through the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway and the suppression of nuclear factor-κB (NF-κB) signaling pathway and their downstream targets. The results showed that pretreatment with di-O-demethylcurcumin elevated cell viability and decreased the level of reactive oxygen species. Moreover, treatment with di-O-demethylcurcumin promoted the translocation of Nrf2 protein from the cytoplasm to the nucleus, increased the expression of Nrf2-ARE pathway-related downstream proteins including heme oxygenase (HO-1), NAD(P)H:quinone oxidoreductase 1 and glutamate-cysteine ligase catalytic subunit, and increased the activity of superoxide dismutase enzymes. On the other hand, di-O-demethylcurcumin suppressed the degradation of IκBα, translocation of the p65 subunit of NF-κB from cytoplasm to nucleus and thereby, attenuated the expression of inducible nitric oxide synthase protein and nitric oxide production. Taken together, these results suggest that neuroinflammatory effect of di-O-demethylcurcumin might potentially be due to inhibit NF-κB and activate Nrf2 signaling pathways induced by Aβ25-35.

Selenofuranoside Ameliorates Memory Loss in Alzheimer-Like Sporadic Dementia: AChE Activity, Oxidative Stress, and Inflammation Involvement

Alzheimer's disease (AD) is becoming more common due to the increase in life expectancy. This study evaluated the effect of selenofuranoside (Se) in an Alzheimer-like sporadic dementia animal model. Male mice were divided into 4 groups: control, Aβ, Se, and Aβ + Se. Single administration of Aβ peptide (fragments 25-35; 3 nmol/3 μL) or distilled water was administered via intracerebroventricular (i.c.v.) injection. Selenofuranoside (5 mg/kg) or vehicle (canola oil) was administered orally 30 min before Aβ and for 7 subsequent days. Memory was tested through the Morris water maze (MWM) and step-down passive-avoidance (SDPA) tests. Antioxidant defenses along with reactive species (RS) were assessed. Inflammatory cytokines levels and AChE activity were measured. SOD activity was inhibited in the Aβ group whereas RS were increased. AChE activity, GSH, and IL-6 levels were increased in the Aβ group. These changes were reflected in impaired cognition and memory loss, observed in both behavioral tests. Se compound was able to protect against memory loss in mice in both behavioral tests. SOD and AChE activities as well as RS and IL-6 levels were also protected by Se administration. Therefore, Se is promising for further studies.

Nitrosative and cognitive effects of chronic L-DOPA administration in rats with intra-nigral 6-OHDA lesion

Besides motor disturbances, other symptoms found in the early stage of Parkinson's disease (PD) are deficits in both learning and memory. The nigro-striatal-cortical pathway is affected in this pathology, with this neuronal circuit involved in cognitive processes such as spatial working memory (SWM). However, cognitive dysfunction appears even when the patients are receiving L-DOPA treatment. There is evidence that the dopamine metabolism formed by L-DOPA generates free radicals such as nitric oxide, which may cause damage through the nitrosative stress (NS). The aim of this study was to evaluate both the effects of chronic L-DOPA administration on SWM and the production of NS in rats using an intra-nigral lesion caused by 6-hydroxydopamine (6-OHDA). Post-lesion, the animals were administered orally with L-DOPA/Carbidopa (100-mg/kg) for 20 days. An SWM task in a Morris water maze was conducted post-treatment. Nitrite levels and immunoreactivity of 3-Nitrotyrosine (3-NT), Inducible Nitric Oxide Synthase (iNOS), Glial Fibrillary Acidic Protein (GFAP), and Tyrosine Hydroxylase (TH) were evaluated in the substantia nigra pars compacta, the dorsal striatum and the medial prefrontal cortex. Our results show that chronic L-DOPA administration in rats with intra-nigral 6-OHDA-lesion caused significant increases in SWM deficit, nitrite levels and the immunoreactivity of 3-NT, iNOS and GFAP in the nigro-striatal-cortical pathway. These facts suggest that as L-DOPA can induce NS in rats with dopaminergic intra-nigral lesion, it could play a key role in the impairment of the SWM, and thus can be considered as a toxic mechanism that induces cognitive deficit in PD patients.