Step-down Passive Avoidance Test Research Articles

Synthesis and evaluation of butylphthalide-scutellarein hybrids as multifunctional agents for the treatment of Alzheimer's disease

A series of butylphthalide and scutellarein hybrids 3-(alkyl/alkenyl) hydroxyphthalide derivatives were designed, synthesized and evaluated as multifunctional agents against Alzheimer's disease. In vitro bioactivity assays indicated that most of the compounds displayed excellent antioxidant activity and moderate to good inhibition activities of self-induced Aβ1-42 aggregation. Among them, compound 7c was demonstrated as a potential and balanced multifunctional candidate displaying the best inhibitory effects on self- and Cu2+-induced Aβ1–42 aggregation (90.2 % and 35.4 %, respectively) and moderate activity for disaggregation of Aβ1-42 aggregation (42.5 %). In addition, 7c also displayed excellent antioxidant (2.42 Trolox equivalents), metal ions chelating, oxidative stress alleviation, neuroprotective and anti-neuroinflammatory activities. Furthermore, in vivo study demonstrated that 7c could ameliorate the learning and memory impairment induced by sodium nitrite and Aβ1-42 in the step-down passive avoidance test. These balanced multifunctional profiles supporting compound 7c as a novel potential candidate for the treatment of AD.

Radioprotective effect of Ginkgolide B on brain: the mediating role of DCC/MST1 signaling

Purpose The risk of brain exposure to ionizing radiation increases gradually due to the extensive application of nuclear technology in medical, industrial, and aerospace fields. Radiation-induced brain injury (RBI) is highly likely to cause a wide range of neurological complications, including schizophrenia, Alzheimer’s disease (AD), depression. Ginkgolide B (GB) is one of the effective active components extracted from ginkgo biloba leaves, exerts protective effects on CNS, which is involved in the regulation of the Hippo signaling pathway. MST1, as one of the core kinases of the Hippo pathway, participated in regulating cell proliferation, differentiation, and apoptosis. However, it remains unclear whether GB attenuates radiation brain injury (RBI) and whether the radioprotective effect of GB refers to MST1 signaling. Hence, our study aimed to explore the radiation protection effect and the potential mechanism of GB. Materials and methods C57BL/6 mice were stimulated with an X-ray (20 Gy) to establish an RBI model. Then, morris water maze test (MWM) and step-down passive avoidance test (SDPAT) were used to assess the learning and memory function of mice. The open field test (OFT), tail suspension test (TST), and forced swimming test (FST) were used to assess changes in locomotor activity and hopelessness. Besides, X-ray-stimulated SH-SY5Y cells were used to verify the radioprotective effect of GB. Immunofluorescence double staining, Dihydroethidium (DHE), western blot, and flow cytometry were used to explore the role of DCC/MST1 signaling in RBI. Results In this study, X-ray-treated mice exhibited cognitive impairment and depression-like behavior, which was ameliorated by GB treatment. GB also reduced the ROS production and the number of TUNEL-positive cells in the hippocampus. Moreover, GB increased the protein levels of p-AKT and Bcl2, while decreased the protein levels of MST1, p-p38, p-JNK, cleaved-caspase-3 and Bax both in vivo and in vitro. Additionally, exogenous Netrin-1 alleviated X-ray-induced ROS production and apoptosis, whereas knockout of Netrin-1 receptor DCC abolished the protective effect of GB. Conclusion Oxidative stress and MST1-mediated neuronal apoptosis participated in radiation-induced cognitive impairment and depression-like behaviors, and modulation of DCC by GB was an effective intervention against RBI.

Effects of HAR1 on cognitive function in mice and the regulatory network of HAR1 determined by RNA sequencing and applied bioinformatics analysis.

Background: HAR1 is a 118-bp segment that lies in a pair of novel non-coding RNA genes. It shows a dramatic accelerated change with an estimated 18 substitutions in the human lineage since the human-chimpanzee ancestor, compared with the expected 0.27 substitutions based on the slow rate of change in this region in other amniotes. Mutations of HAR1 lead to a different HAR1 secondary structure in humans compared to that in chimpanzees. Methods: We cloned HAR1 into the EF-1α promoter vector to generate transgenic mice. Morris water maze tests and step-down passive avoidance tests were conducted to observe the changes in memory and cognitive abilities of mice. RNA-seq analysis was performed to identify differentially expressed genes (DEGs) between the experimental and control groups. Systematic bioinformatics analysis was used to confirm the pathways and functions that the DEGs were involved in. Results: Memory and cognitive abilities of the transgenic mice were significantly improved. The results of Gene Ontology (GO) analysis showed that Neuron differentiation, Dentate gyrus development, Nervous system development, Cerebral cortex neuron differentiation, Cerebral cortex development, Cerebral cortex development and Neurogenesis are all significant GO terms related to brain development. The DEGs enriched in these terms included Lhx2, Emx2, Foxg1, Nr2e1 and Emx1. All these genes play an important role in regulating the functioning of Cajal-Retzius cells (CRs). The DEGs were also enriched in glutamatergic synapses, synapses, memory, and the positive regulation of long-term synaptic potentiation. In addition, "cellular response to calcium ions" exhibited the second highest rich factor in the GO analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the DEGs showed that the neuroactive ligand-receptor interaction pathway was the most significantly enriched pathway, and DEGs also notably enriched in neuroactive ligand-receptor interaction, axon guidance, and cholinergic synapses. Conclusion: HAR1 overexpression led to improvements in memory and cognitive abilities of the transgenic mice. The possible mechanism for this was that the long non-coding RNA (lncRNA) HAR1A affected brain development by regulating the function of CRs. Moreover, HAR1A may be involved in ligand-receptor interaction, axon guidance, and synapse formation, all of which are important in brain development and evolution. Furthermore, cellular response to calcium may play an important role in those processes.

Ginsenoside ompound K reduces neuronal damage and improves neuronal synaptic dysfunction by targeting Aβ.

Background: Alzheimer's disease (AD) is the most common neurodegenerative condition worldwide, with amyloid ß (Aβ) fibrils presenting as its main pathological feature. This study investigated whether Ginsenoside Compound K (CK) has activity against Aβ and its mechanism in reducing synaptic damage and cognitive impairment. Methods: The binding capacity of CK to Aβ42 and Nrf2/Keap1 was determined using molecular docking. Transmission electron microscopy was used to monitor CK-mediated degradation of Aβ fibrils. The effect of CK on the survival of Aβ42-damaged HT22 cells was determined using a CCK-8 assay. The therapeutic efficacy of CK in a scopoletin hydrobromide (SCOP) induced cognitive dysfunction mouse model was measured using a step-down passive avoidance test. GO enrichment analysis of mouse brain tissue was peformed using Genechip. Hydroxyl radical scavenging and reactive oxygen species assays were performed to verify the antioxidant activity of CK. The effects of CK on the expression of Aβ42, the Nrf2/Keap1 signaling pathway, and other proteins were determined by western blotting, immunofluorescence, and immunohistochemistry. Results: Molecular docking results showed that CK interacts with Lys16 and Glu3 of Aβ42. CK reduced the aggregation of Aβ42 as observed using transmission electron microscopy. CK increased the level of insulin-degrading enzyme and decreased the levels ß-secretase and γ-secretase; therefore, it can potentially inhibit the accumulation of Aβ in neuronal extracellular space in vivo. CK improved cognitive impairment and increased postsynaptic density protein 95 and synaptophysin expression levels in mice with SCOP-induced cognitive dysfunction. Further, CK inhibited the expression of cytochrome C, Caspase-3, and cleaved Caspase-3. Based on Genechip data, CK was found to regulate molecular functions such as oxygen binding, peroxidase activity, hemoglobin binding, and oxidoreductase activity, thus affecting the production of oxidative free radicals in neurons. Further, CK regulated the expression of the Nrf2/Keap1 signaling pathway through its interaction with the Nrf2/Keap1 complex. Conclusion: Our findings show that CK regulates the balance between Aβ monomers production and clearance, CK binds to Aβ monomer to inhibits the accumulation of Aβ, increases the level of Nrf2 in neuronal nuclei, reduces oxidative damage of neurons, improves synaptic function, thus ultimately protecting neurons.

Chinese herbal compound Jinsiwei improves synaptic plasticity in mice with sporadic Alzheimer's disease induced by streptozotocin.

To investigate the efficacy of Jinsiwei (a patented Chinese herbal compound) on learning and memory impairment, the number of synapses and synaptic plasticity-related structural and functional protein expression in mice with sporadic Alzheimer's disease (SAD) induced by streptozotocin. Seventy-five C57/BL6J male mice were intracerebroventricularly injected with streptozotocin to establish the animal model of SAD. Mice were randomly divided into the model group (MG), donepezil group (DG), and the Jinsiwei high, medium, and low-dose groups (JH, JM, JL). Another fifteen C57/BL6J male mice were injected with artificial cerebrospinal fluid as the control group (CG). The intervention groups were intragastrically administrated with corresponding medicine, while the CG and MG were given 0.5% carboxymethyl cellulose by gavage. After 3 months, the Morris Water Maze test and step-down passive avoidance test were used to assess the learning and memory ability of mice. Synapses in hippocampal CA1 were observed by transmission electron microscope. Immunohistochemistry and western blotting were used to assess the distribution and expression levels of synaptic plasticity-related structural and functional proteins involving drebrin, cofilin, synapsin (syn), and N-methyl D-aspartate receptor subtype 2B (NR2B). The Morris Water Maze results showed that the escape latency in the Jinsiwei intervention groups was significantly shorter than that of the MG. Results of the step-down passive-avoidance test showed that the error times in the Jinsiwei intervention groups were significantly reduced compared with the MG. Transmission electron microscope results showed that the number of synapses in hippocampal CA1 was obviously increased in the Jinsiwei intervention groups compared with the MG. Immunohistochemical and western blotting results revealed that the positive cells and expression levels of drebrin, syn, and NR2B were significantly decreased in the MG and meanwhile cofilin significantly increased, while these changes were reversed after the Jinsiwei treatment. Jinsiwei can alleviate learning and memory impairments in a mouse model of SAD, increase the number of synapses and enhance synaptic plasticity rescuing the expression of drebrin, syn, and NR2B and inhibiting cofilin expression.

Hydrogen Inhalation Ameliorates Oxidative Stress and Glucose Metabolism Disorder in the Brain of Hindlimb Unloading Rats

Many studies have shown that spaceflight causes oxidative stress and induces brain disorder in astronauts, but the counter measurements are lacking. Increasing evidence demonstrated that hydrogen can act as a therapeutic antioxidant. In this study, rats were treated with or without about 5% hydrogen under hindlimb unloading or normal conditions for 28 d. We assessed rat’s brain function by open-field test, step-down passive avoidance test, the neurotransmitter’s level detected by liquid chromatography with tandem mass spectrometry, and Nissl and hematoxylin–eosin staining analysis. We also assessed the oxidative damage by changes of malondialdehyde level, the ratio of reduced glutathione to oxidized glutathione, and superoxide dismutase and catalase activity. Glucose metabolism disorder was disclosed through glucose metabolomic analysis. The underlying mechanism of the effects of hydrogen was analyzed by mRNA sequencing and detecting mRNA and protein levels. Our data showed that hindlimb unloading caused oxidative damage and glucose metabolism disorder in brain tissues and decreased brain function in rats. Hydrogen inhalation reduced oxidative damage, ameliorated glucose metabolism disorder, and alleviated the dysfunction of rat brain function. Peroxisome-proliferator-activated receptor gamma coactivator 1α and brain-derived neurotrophic factor, the key regulators of glucose metabolism and brain function, were obviously affected. This research confirms the protective effect of hydrogen inhalation on declining brain function under hindlimb unloading conditions and discloses the underlying mechanism, which provides a potential strategy for astronauts’ health.

Effect of consumption of blue maize tortilla on anxiety-like behaviour, learning, memory and hippocampal BDNF expression in a chronic stress model in rats

ABSTRACT Background Pigmented maize consumption is of much interest because of its high anthocyanin content and multiple health benefits. Objetives: This study was aimed to assess the effect of consuming blue maize tortillas on the anxiolytic capacity, preserve emotional memory, and the expression of brain-derived neurotrophic factor (BDNF) in rats subjected to chronic stress. Methods: Sixty-four 3-month-old male Wistar rats were used, divided into eight groups (n = 8). Four groups were subjected to chronic stress by movement restriction (7 h/daily/7 consecutive days) and the remaining four groups were subjected to standard management. The treatments were commercial food, blue tortilla, anthocyanin extract, or white tortilla, administered for nine weeks to stressed or unstressed animals. In the eighth week, the animals were subjected to the restraint stress model. Subsequently, anxiety-like behaviour was assessed using the elevated plus-maze, and memory and emotional learning were evaluated by the step-down passive avoidance test. The animals were then sacrificed to quantify the relative expression of hippocampal BDNF by RT-qPCR. Results: The consumption of anthocyanin extract or tortilla made with blue corn decreased anxiety-like behaviours, additionally, it improved the ability to retain emotionally relevant information, and it upregulated BDNF mRNA expression. Perspective: Thus, the analyse of the impact of blue tortilla consumption on the nervous system is now necessary to guarantee the nutraceutical value of this food.

First evaluation of the anxiolytic-like effects of a bromazepam‑palladium complex in mice

A significant fraction of patients are affected by persistent fear and anxiety. Currently, there are several anxiolytic drug options, however their clinical outcomes do not fully manage the symptoms. Here, we evaluated the effects of a bromazepam‑palladium derivative [2-{(7-bromo-2-oxo-1,3-dihydro-2H-1,4-benzodiazepin-5-il)pyridinyl-κ2-N,N}chloropalladium(II)], [(BMZ)PdCl2], on fear/anxiety and memory-related behavior in mice. For this, female Swiss mice were treated intraperitoneally (i.p.) with saline (NaCl 0.9%) or [(BMZ)PdCl2] (0.5, 5.0, or 50 μg/kg). After 30 min, different tests were performed to evaluate anxiety, locomotion, and memory. We also evaluated the acute toxicity of [(BMZ)PdCl2] using a cell viability assay (neutral red uptake assay), and whether the drugs mechanism of action involves the γ-aminobutyric acid type A (GABAA) receptor complex by pre-treating animals with flumazenil (1.0 mg/kg, i.p., a competitive antagonist of GABAA-binding site). Our results demonstrate that [(BMZ)PdCl2] induces an anxiolytic-like phenotype in the elevated plus-maze test and that this effect can be blocked by flumazenil. Furthermore, there were no behavioral alterations induced by [(BMZ)PdCl2], as evaluated in the light-dark box, open field, and step-down passive avoidance tests. In the acute toxicity assay, [(BMZ)PdCl2] presented IC50 and LD50 values of 218 ± 60 μg/mL and 780 ± 80 mg/kg, respectively, and GSH category 4. Taken together, our results show that the anxiolytic-like effect of acute treatment with [(BMZ)PdCl2] occurs through the modulation of the benzodiazepine site in the GABAA receptor complex. Moreover, we show indications that [(BMZ)PdCl2] does not promote sedation and amnesia and presents the same toxicity as the bromazepam prototype.

Tongluo Huatan capsule improves cognitive function by regulating the endocytosis of N-methyl-D-aspartic acid receptors mediated by clathrin in a rat model of vascular dementia.

To explore the neuroprotective mechanisms of Tongluo Huatan capsule (THC) in a rat model of vascular dementia (VD). A rat model of VD was established by repeated clamping of bilateral common carotid arteries with the intraperitoneal injection of sodium nitroprusside solution. VD rats were administered THC, memantine hydrochloride, or distilled water daily for 14 d after operation. Learning and memory abilities were assessed using the step-down passive avoidance test, novel object recognition (NOR) test, and Morris water maze (MWM) test. Pathological changes in the hippocampus were observed through hematoxylin and eosin and Nissl staining. The expression levels of clathrin, RAB5B, and N-methyl-D-aspartic acid receptor 1 (NMDAR1) were measured by immunohistochemistry staining, real-time quantitative polymerase chain reaction and Western blot. Rats in VD group showed impaired learning and memory abilities (step-down passive avoidance, NOR, and MWM) and abnormalities in neuronal morphology (light microscopy) in the hippocampus. The mRNA or protein expression levels of clathrin and RAB5B were decreased, and NMDAR1 was increased in hippocampal tissues (P < 0.05). Administration of THC promoted the learning and memory abilities and the morphological structure of hippocampal neurons in VD rats. Besides, THC enhanced mRNA or protein expression levels of clathrin and RAB5B, and decreased NMDAR1 (P < 0.05). THC may improve cognitive functions by regulating the endocytosis of NMDA receptors mediated by clathrin.

Phosphodiesterase-4D Knockdown in the Prefrontal Cortex Alleviates Memory Deficits and Synaptic Failure in Mouse Model of Alzheimer’s Disease

Phosphodiesterase 4 (PDE4)-dependent cAMP signaling plays a crucial role in cognitive impairment associated with Alzheimer’s disease (AD). However, whether inhibition of PDE4 subtypes or their splice variants in the prefrontal cortex positively regulates synaptic plasticity and antioxidative stress, and reverses β-amyloid 1–42 (Aβ1–42, Aβ42)-induced cognitive impairment still need to be clarified. The present study determined whether and how PDE4D knockdown by microinjection of lenti-PDE4D-miRNA into the prefrontal cortex reversed Aβ1–42-induced cognitive impairment in behavioral, neurochemical, and molecular biology assays. The results suggested that PDE4D knockdown increased time to explore the novel object and decreased latency to leave the platform in novel object recognition and step-down passive avoidance tests. Further study suggested that PDE4D knockdown decreased the number of working memory errors in the eight-arm maze test. These effects were prevented by PKA inhibitor H89. The subsequent experiment suggested that inhibition of PDE4D in the prefrontal cortex rescued the long-term potentiation (LTP) and synaptic proteins’ expression; it also increased antioxidant response by increasing superoxide dismutase (SOD) and decreasing malondialdehyde (MDA) levels. PDE4D knockdown also increased phosphorylated cAMP response element-binding protein (pCREB), brain-derived neurotrophic factor (BNDF), and anti-apoptotic proteins’ expression, i.e., the ratio of Bcl-2/Bax, and decreased caspase-3 level in the prefrontal cortex. These findings extend the previous findings and support the hypothesis that RNA interference-mediated PDE4D knockdown in the prefrontal cortex ameliorated memory loss associated with synaptic failure in an AD mouse model by its antioxidant, anti-apoptotic, and neuroprotective properties.

An experimental study on phytochemical composition and memory enhancing effect of Ginkgo biloba seed extract.

The Ginkgo biloba L. tree is considered as one of the oldest species on Earth. It is known as a "living fossil" dating back approximately 200 million years. Both the leaves and seeds of this tree have been used for millennia in traditional Chinese medicine. To study the phytochemical profile of Gingko biloba seed extract (GBSE) and its memory enhancing effects. Liquid chromatography with mass detection (LC-MS) was performed for phytochemical analyses of the extracts. For the in vivo experiments, male Wistar rats were divided randomly into 5 groups (n=8): saline; piracetam; GBSE 50; 100, and 200 mg/kg b.w. Y-maze, T-maze, step-down passive avoidance and novel object recognition test (NORT) were performed. The observed parameters were: percentage of spontaneous alternations (% SA), working memory index, latency of reaction and recognition index, respectively. Statistical analysis was done using SPSS 19. LC-MS analysis showed the presence of the flavonoids quercetin, kaempferol and isorhamnetin (as aglycones), the ginkgolides A, B, C, J, and bilobalide. In Y-maze task, the groups treated with 50 and 100 mg/kg of GBSE significantly increased the % SA during the memory test compared to saline (p<0.05). In T-maze test, the three experimental groups with GBSE significantly increased the working memory index in comparison with that of the control group (p<0.05). In step-down test, the animals receiving 100 mg/kg b.w. GBSE, notably increased the latency during both retention tests (p<0.05 and p<0.01, respectively). In NORT, only the animals with the middle dose of GBSE ameliorated the recognition index when compared to saline (p<0.05). GBSE enhances spatial working memory, recognition memory, and short- and long-term recall in naïve rats due to the synergic effects of detected flavonoids and terpene lactones on brain functions. The brain structures involved are probably the hippocampus and prefrontal cortex.

The Effect of Chronic Treatment with Lacosamide and Topiramate on Cognitive Functions and Impaired Emotional Responses in a Pilocarpine-induced Post-statusEpilepticus Rat Model.

Epilepsy and antiepileptic drugs can affect negatively the cognitive abilities of patients. The present study aimed to evaluate the effect of topiramate (TPM) and lacosamide (LCM) on the emotional and cognitive re-sponses in naive animals and in animals with pilocarpine-induced status epilepticus. Male Wistar rats were randomly divided into 6 groups and status epilepticus was evoked in half of them by a single i.p. administration of pilocarpine (Pilo) (320 mg/kg): Pilo-veh, Pilo-TPM (80 mg/kg) and Pilo-LCM (30 mg/kg). Matched naive rats were treated with the same doses as follows: C-veh, C-TPM, and C-LCM. In a step-down passive avoidance test, the learning session was held for one day, the early retention test was conducted on day 2, and the long-term memory test - on day 7. Motor activity and anxiety were evaluated in an open field test. The Pilo-TPM and Pilo-LCM groups increased the time spent on the platform compared to Pilo-veh animals while the C-LCM animals decreased the time compared to C-veh animals during short- and long-term memory retention tests. TPM and LCM exerted an anxiolytic effect in naive rats. The two antiepileptic drugs were unable to alleviate the hyperactivity, but they alleviated the impulsivity associated with decreased anxiety level in epileptic rats. Our findings suggest that LCM and TPM have a beneficial effect on cognition both in naive and epileptic rats. While the two antiepileptic drugs can produce an anxiolytic effect in naive rats, they alleviate the impulsivity after pilocarpine treatment.

Discussion of the promising effect of electroacupuncture on cognitive improvement in D-galactose-induced aging rats based on NLRP3-ASC-Caspase-1 signaling pathway

To investigate the effect of electroacupuncture (EA) on cognitive function in D-galactose (D-gal)-induced aging rats, and the correlation between the effect and nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3)-ASC-Caspase-1 signaling pathway. Forty-six male Sprague-Dawley (SD) rats were randomly divided into a control group (n=10), a model group (n=12), an EA-7 d group (n=12) and an EA-21 d group (n=12). Except the control group, the other three groups received 42 consecutive days of intraperitoneal injection of D-gal to establish aging rat models with cognitive dysfunction. The control group received the same amount of normal saline via intraperitoneal injection. Two EA groups were given EA therapy for 21 consecutive days (began from the 22nd day of modeling) or 7 consecutive days (began from the 36th day of modeling) accordingly at Dazhui (GV 14), Baihui (GV 20), Shenshu (BL 23) and Zusanli (ST 36). After modeling/intervention, all four groups received behavioral evaluations by Morris water maze (MWM) test, novel object recognition (NOR) test and step-down passive avoidance (SDPA) test followed by the Western blot (WB) detection of the expression levels of hippocampal NLRP3 inflammasome-associated proteins NLRP3, ASC and Caspase-1. MWM (place navigation test, PNT) results showed that the escape latency in the model group was significantly longer than that in the other three groups (P 0.05). From the 2nd day to the 4th day of the test, there was no significant difference between the EA-21 d group and the control group (P>0.05) in the escape latency; the escape latency was significantly shorter in the EA-21 d group than in the model group and the EA-7 d group (P 0.05). NOR results showed that there was no significant difference in the recognition ratio between the EA-7 d group and the EA-21 d group (P>0.05), and the recognition ratio was significantly higher in the two EA groups than in the model group (P 0.05). The model group had the shortest step-down latency, followed by the EA-7 d group, the EA-21 d group and the control group in order (P 0.05). NLRP3 inflammasome may be involved in the development of cognitive decline in aging rats; 7 consecutive days of EA intervention can partially improve the cognitive impairment in aging rats though the effect is rather limited; 21 consecutive days of EA intervention may improve the learning and memory abilities in aging rats via down-regulating the expression levels of NLRP3 inflammasome-associated proteins in hippocampus.

Beta amyloid-induced time-dependent learning and memory impairment: involvement of HPA axis dysfunction.

Aβ aggregation is one of the pathological biomarkers of Alzheimer's disease (AD). However, the possible mechanism related to Aβ-induced pathological signaling pathway is still unknown. In the present study, Aβ1-42-induced time-dependent memory impairment and its possible relationship to hypothalamic-pituitary-adrenal (HPA) axis hyperactivity were examined. Aβ1-42-treated mice significantly impaired acquisition activity in the learning curve at 10days, 1 and 4months in the Morris water-maze (MWM) task. This learning activity was back to normal at 8months after Aβ1-42 treatment. In the probe trial test, Aβ1-42-treated mice needed longer latencies to touch the precious platform location and fewer numbers of crossing from 10days to 4months after microinjection. This Aβ1-42 induced memory loss was consistent with the results of the step-down passive avoidance test. The HPA axis related parameters, such as corticosterone (CORT) level in the serum, glucocorticoid receptor (GR) and corticotropin-releasing factor receptor (CRF-R) expression in the frontal cortex and hippocampus increased in Aβ1-42-treated mice from 10days to 4months. While the downstream molecules phosphorylation of cyclic AMP response element binding (pCREB) and brain-derived neurotrophic factor (BDNF) expression decreased during this time. These effects were back to normal 8months after treatment with Aβ1-42. Altogether, our results suggested that Aβ1-42 induced significant learning and memory impairment, which is involved in HPA axis dysfunction.

GAPT regulates cholinergic dysfunction and oxidative stress in the brains of learning and memory impairment mice induced by scopolamine

BackgroundCholinergic dysfunction and oxidative stress are the crucial mechanisms of Alzheimer's disease (AD). GAPT, also called GEPT (a combination of several active components extracted from the Chinese herbs ginseng, epimedium, polygala and tuber curcumae) or Jinsiwei, is a patented Chinese herbal compound, has been clinically widely used to improve learning and memory impairment, but whether it can play a neuroprotective role by protecting cholinergic neurons and reducing oxidative stress injury remains unclear.MethodsMale ICR mice were intraperitoneally injected with scopolamine (3 mg/kg) to establish a learning and memory disordered model. An LC‐MS method was established to study the chemical compounds and in vivo metabolites of GAPT. After scopolamine injection, a step‐down passive‐avoidance test (SDPA) and a Y maze test were used to estimate learning ability and cognitive function. In addition, ELISA detected the enzymatic activities of acetylcholinesterase (AChE), acetylcholine (ACh), choline acetyltransferase (ChAT), malondialdehyde (MDA), glutathione peroxidase (GPX), and total superoxide dismutase (T‐SOD). The protein expressions of AChE, ChAT, SOD1, and GPX1 were observed by western blot, and the distribution of ChAT, SOD1, and GPX1 was observed by immunohistochemical staining.ResultsAfter one‐half or 1 month of intragastric administration, GAPT can ameliorate scopolamine‐induced behavioral changes in learning and memory impaired mice. It can also decrease the activity of MDA and protein expression level of AChE, increase the activity of Ach, and increase activity and protein expression level of ChAT, SOD, and GPX in scopolamine‐treated mice. After one and a half month of intragastric administration of GAPT, echinacoside, salvianolic acid A, ginsenoside Rb1, ginsenoside Rg2, pachymic acid, and beta asarone could be absorbed into mice blood and pass through BBB.ConclusionsGAPT can improve the learning and memory ability of scopolamine‐induced mice, and its mechanism may be related to protecting cholinergic neurons and reducing oxidative stress injury.

Design, synthesis and evaluation of phthalide alkyl tertiary amine derivatives as promising acetylcholinesterase inhibitors with high potency and selectivity against Alzheimer's disease

A series of phthalide alkyl tertiary amine derivatives were designed, synthesized and evaluated as potential multi-target agents against Alzheimer’s disease (AD). The results indicated that almost all the compounds displayed significant AChE inhibitory and selective activities. Besides, most of the derivatives exhibited increased self-induced Aβ1-42 aggregation inhibitory activity compared to the lead compound dl-NBP, and some compounds also exerted good antioxidant activity. Specifically, compound I-8 showed the highest inhibitory potency toward AChE (IC50 = 2.66 nM), which was significantly better than Donepezil (IC50 = 26.4 nM). Moreover, molecular docking studies revealed that compound I-8 could bind to both the catalytic active site and peripheral anionic site of AChE. Furthermore, compound I-8 displayed excellent BBB permeability in vitro. Importantly, the step-down passive avoidance test indicated that I-8 significantly reversed scopolamine-induced memory deficit in mice. Collectively, these results suggested that I-8 might be a potent and selective AChE inhibitor for further anti-AD drug development.

Type 3 adenylyl cyclase in the MOE is involved in learning and memory in mice

Although olfactory dysfunction is related to learning and memory impairment, the causal relationship between main olfactory epithelium (MOE) disruption and learning and memory is still unknown. The present study aimed to establish whether MOE disruption causes learning and memory impairment and whether the expression of type 3 adenylyl cyclas (AC3) in the MOE is related to learning and memory. First, the buried food test was carried out to confirm that MOE function was disrupted in mice treated with nasal instillation of zinc sulfate (ZnSO4 mice), and mice with specific knockdown of AC3 in the MOE by CRISPR/Cas9 technology (AC3KD/MOE mice). Then, behavioural tasks associated with learning and memory were administered. ZnSO4 mice and AC3KD/MOE mice showed impairments in learning and memory tests, including the novel object recognition test, the step-down passive avoidance test, the Morris water maze test, and the Y-maze test. Our data demonstrate that MOE disruption caused by nasal exposure to ZnSO4 or specific knockdown of AC3 in the MOE resulted in learning and memory impairment, and they further demonstrate that the expression of AC3 in the MOE plays a major role in learning and memory.

Ultrasound with microbubbles improves memory, ameliorates pathology and modulates hippocampal proteomic changes in a triple transgenic mouse model of Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disease manifested by cognitive impairment. As a unique approach to open the blood-brain barrier (BBB) noninvasively and temporarily, a growing number of studies showed that low-intensity focused ultrasound in combination with microbubbles (FUS/MB), in the absence of therapeutic agents, is capable of ameliorating amyloid or tau pathology, concurrent with improving memory deficits of AD animal models. However, the effects of FUS/MB on both the two pathologies simultaneously, as well as the memory behaviors, have not been reported so far.Methods: In this study, female triple transgenic AD (3×Tg-AD) mice at eight months of age with both amyloid-β (Aβ) deposits and tau phosphorylation were treated by repeated FUS/MB in the unilateral hippocampus twice per week for six weeks. The memory behaviors were investigated by the Y maze, the Morris water maze and the step-down passive avoidance test following repeated FUS/MB treatments. Afterwards, the involvement of Aβ and tau pathology were assessed by immunohistochemical analysis. Neuronal health and phagocytosis of Aβ deposits by microglia in the hippocampus were examined by confocal microscopy. Further, hippocampal proteomic alterations were analyzed by employing two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) combined with mass spectrometry.Results: The three independent memory tasks were indicative of evident learning and memory impairments in eight-month-old 3×Tg-AD mice, which developed intraneuronal Aβ, extracellular diffuse Aβ deposits and phosphorylated tau in the hippocampus and amygdala. Following repeated FUS/MB treatments, significant improvement in learning and memory ability of the 3×Tg-AD mice was achieved. Amelioration in both Aβ deposits and phosphorylated tau in the sonicated hemisphere was induced in FUS/MB-treated 3×Tg-AD mice. Albeit without increase in neuron density, enhancement in axonal neurofilaments emerged from the FUS/MB treatment. Confocal microscopy revealed activated microglia engulfing Aβ deposits in the FUS/MB-treated hippocampus. Further, proteomic analysis revealed 20 differentially expressed proteins, associated with glycolysis, neuron projection, mitochondrial pathways, metabolic process and ubiquitin binding etc., in the hippocampus between FUS/MB-treated and sham-treated 3×Tg-AD mice.Conclusions: Our findings reinforce the positive therapeutic effects on AD models with both Aβ and tau pathology induced by FUS/MB-mediated BBB opening, further supporting the potential of this treatment regime for clinical applications.

Phosphodiesterase-2 Inhibitor Bay 60-7550 Ameliorates Aβ-Induced Cognitive and Memory Impairment via Regulation of the HPA Axis.

The dysfunction of the hypothalamus–pituitary–adrenal (HPA) axis is often seen in Alzheimer’s disease (AD) patients with cognitive deficits. Selective inhibition of phosphodiesterase (PDE) 4 and 5 has already proven to be effective in reducing beta-amyloid 1–42 (Aβ1–42)-mediated pathology by regulating corticotropin-releasing factor (CRF) and glucocorticoid receptor (GR) expression, suggesting that PDE-dependent signaling is involved in Aβ1–42-induced HPA axis dysfunction. However, nausea and vomiting are the side effects of some PDE4 inhibitors, which turn our attention to other PDEs. PDE2 are highly expressed in the hippocampus and cortex, which associate with learning and memory, but not in the area postrema that would cause vomiting. The present study suggested that microinjection of Aβ1–42 to the intracerebroventricle induced learning and memory impairments and dysregulation of the HPA axis by increased expression of CRF and GR. However, the PDE2 inhibitor Bay 60-7550 significantly ameliorated the learning and memory impairment in the Morris water maze (MWM) and step-down passive avoidance tests. The Aβ1–42-induced increased CRF and GR levels were also reversed by the treatment with Bay 60-7550. These Bay 60-7550’s effects were prevented by pretreatment with the PKG inhibitor KT5823. Moreover, the Bay 60-7550-induced downstream phosphorylation of cyclic AMP response element binding (pCREB) and brain-derived neurotrophic factor (BDNF) expression was also prevented (or partially prevented) by KT5823 or the PKA inhibitor H89. These results may lead to the discovery of novel strategies for the treatment of age-related cognitive disorders, such as AD, which affects approximately 44 million people worldwide.

Neuroprotective and Memory-Enhancing Effects of Antioxidant Peptide From Walnut (Juglans regia L.) Protein Hydrolysates

Peptides have been reported to possess interesting biological properties. The present study was designed to evaluate neuroprotective and memory-enhancing effects of antioxidant peptide from walnut ( Juglans regia L.) protein hydrolysates. The neuroprotective effect of walnut peptide (WP) against oxidative stress on PC12 cells was evaluated. And zebrafish was used as the model to corroborate the effect. Its effect on learning and memory of mice using the Morris water maze and the step-down passive avoidance tests were performed. Moreover, the acute toxicity of WP was carried out to assess its safety profile. It was found that WP was able to suppress H2O2-induced cell death in PC12 cells. In the zebrafish model, WP had an obvious neuroprotective effect, and the ratio reached 42% at 222 µg/mL. The mechanism study revealed that WP could inhibit the activity of caspases 3/7 and 8, reduce the mRNA expression levels of Bax and glial cell line-derived neurotrophic factor, and improve the mRNA expression level of brain-derived neurotrophic factor significantly. Besides, the treatment of mice with WP shortened the escape latency and exhibited much longer target time and more crossing times significantly, compared with untreated control groups in the Morris water maze test. Similarly, the step-down passive avoidance test showed that WP could ameliorate memory impairments. The administrated dose (20.1 g/kg body weight [BW]) did not produce mortality or treatment-related adverse effects with regard to BW, general behavior, or relative organ weights of the tested male and female mice. The current results indicated that WP could exert neuroprotective effect, and attenuated learning and memory impairments. These ameliorating effects of WP may be useful for treatment of memory impairment in Alzheimer’s and its related diseases.