Effects of a novel cognitive enhancer, spiro[imidazo-[1,2-a]pyridine-3,2-indan]-2(3H)-one (ZSET1446), on learning impairments induced by amyloid-beta1-40 in the rat

The Aqueous Extract of Humulus japonicus Ameliorates Cognitive Dysfunction in Alzheimer's Disease Models via Modulating the Cholinergic System

Humulus japonicus (HJ) is an herbal medicine, which has been reported as being antioxidative and anti-inflammatory. The present study aimed to investigate the effect of oral administration of HJ water extract (HJW) on cognitive function through the cholinergic system in Alzheimer's disease (AD) mouse models. Institute of Cancer Research mice injected with beta-amyloid (Aβ) (1-42) (i.c.v.) and APP/PS1 transgenic (TG) mice were orally administered with HJW at 500 mg/kg/day for 3 weeks. Aβ-injected mice and APP/PS1 TG mice showed cognitive dysfunction, which was evaluated by various behavioral tests. HJW treatment significantly attenuated memory impairments in Aβ-injected mice and APP/PS1 TG mice. Aβ injection decreased acetylcholine (ACh) concentrations and choline acetyltransferase (ChAT) activity, and increased acetylcholinesterase (AChE) activity. These cholinergic impairments were also found in APP/PS1 TG mice. HJW significantly attenuated cholinergic alterations in Aβ-injected mice and TG mice. In addition, HJW significantly decreased Aβ plaque deposition in the cerebral cortex and hippocampus of TG mice. Therefore, the present study demonstrated that HJW protected against AD-related memory impairments via enhancing the cholinergic system and inhibiting Aβ plaque deposition.

Animal Models of Metabolic Disorders in the Study of Neurodegenerative Diseases: An Overview

The incidence of metabolic disorders, as well as of neurodegenerative diseases—mainly the sporadic forms of Alzheimer’s and Parkinson’s disease—are increasing worldwide. Notably, obesity, diabetes, and hypercholesterolemia have been indicated as early risk factors for sporadic forms of Alzheimer’s and Parkinson’s disease. These conditions share a range of molecular and cellular features, including protein aggregation, oxidative stress, neuroinflammation, and blood-brain barrier dysfunction, all of which contribute to neuronal death and cognitive impairment. Rodent models of obesity, diabetes, and hypercholesterolemia exhibit all the hallmarks of these degenerative diseases, and represent an interesting approach to the study of the phenotypic features and pathogenic mechanisms of neurodegenerative disorders. We review the main pathological aspects of Alzheimer’s and Parkinson’s disease as summarized in rodent models of obesity, diabetes, and hypercholesterolemia.

Novel D-π-A type near-infrared fluorescent probes for the detection of Aβ40 aggregates

Aberrant accumulation of Amyloid-β (Aβ) peptide is closely related to Alzheimer's disease. Thus, it is important to develop featured probes for the specific detection of Aβ species. Herein, we designed and synthesized a novel near-infrared fluorescent probe SDPY based on the D-π-A architecture for the detection of Aβ aggregates. The probe SDPY displayed higher affinity for Aβ40 aggregates over Aβ42 aggregates in solution (Kd = 164 nM vs. 2.1 μM). In addition, SDPY showed excellent anti-interference against a wide range of other substances. Furthermore, SDPY was capable of labeling Aβ40 aggregates better than Aβ42 aggregates in the brain sections of AD transgenic mouse models.

[Role of T-type Calcium Channels in Regulating Neuronal Function]

T-type calcium channels are low-threshold voltage-gated calcium channel and characterized by unique electrophysiological properties such as fast inactivation and slow deactivation kinetics. All subtypes of T-type calcium channel (Cav3.1, 3.2 and 3.3) are widely expressed in the central nerve system, and they have an important role in homeostasis of sleep, pain response, and development of epilepsy. Recently, several reports suggest that T-type calcium channels may mediate neuronal plasticity in the mouse brain. We succeeded to develop T-type calcium channel enhancer ethyl 8'-methyl-2',4-dioxo-2-(piperidin-1-yl)-2'H-spiro[cyclopentane-1,3'-imidazo[1,2-a]pyridine]-2-ene-3-carboxylate (SAK3) which enhances Cav3.1 and 3.3 currents in each-channel expressed neuro2A cells. SAK3 can promote acetylcholine (ACh) release in the mouse hippocampus via enhancing T-type calcium channel. In this review, we have introduced the role of T-type calcium channel, especially Cav3.1 channel in the mouse hippocampus based on our previous data using SAK3 and Cav3.1 knockout mice.

Effects of porcine brain hydrolysate on impairment of cognitive learning ability in amyloid β(1-40) -infused rats

This study assessed whether administering porcine brain hydrolysate (PBH) ameliorates the impairment of spatial cognition learning ability in amyloid β (Aβ)-infused rats. PBH was prepared using organic solvents (i.e., acetone and ethanol). Enzyme hydrolysates were derived from these PBH and the sequence of the Aβ peptide for infusion was selected. The results indicated the PBH, in particular EP (porcine brain extract with ethanol and protease N), demonstrated the potentials to reduce damage of neurodegenerative disorders in vitro and in vivo. The principal findings of this study indicate that PBH has prolyl endopeptidase inhibitory activity in vitro. Moreover, administering EP to Aβ(1-40)-infused rats significantly improves their performance on reference, spatial performance, and working memory tests during water maze tasks; concurrent proportional decreases are also observed in malondialdehyde levels, acetylcholinesterase (AChE) activity, and Aβ accumulation levels in brain tissues. The PBH was suggested to ameliorate learning deficits associated with Alzheimer's disease by inhibition of lipid peroxidation in the brain of Aβ infused rat.

Effect and mechanism of oyster hydrolytic peptides on spatial learning and memory in mice

Oysters (Crassostrea talienwhanensis) contain large amounts of protein and exhibit many biological activities. This study was aimed at preparing oyster protein hydrolysates (OPH) and evaluating the OPH based on a spatial learning and memory capacity. A response surface methodology was employed to optimize hydrolysis conditions to determine the OPH with the highest AChE inhibitory activity, and the optimum extraction conditions were as follows: enzyme concentration of 1444.88 U g-1, pH of 7.38, extraction temperature of 45 °C, extraction time of 5.56 h and a water/material ratio of 2.45 : 1, and the minimum acetylcholinesterase (AChE) activity was 0.069 mM min-1. The spatial memory and learning abilities and passive avoidance in mice were determined by using the Morris water maze test and a dark/light avoidance test. Furthermore, the OPH group could relieve oxidative stress, reduce AChE levels, increase choline acetyltransferase (ChAT) levels and alleviate inflammatory reaction through reduction of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels. Additionally, up-regulated expressions of brain-derived neurotrophic factor (BDNF) and neural cell adhesion molecules (NCAM) were observed in mice treated with OPH. These findings suggested that OPH could be a functional food candidate to improve the learning and memory ability associated with oxidative stress and inflammatory reactions.

Amyloid Beta Peptides Block New Synapse Assembly by Nogo Receptor-Mediated Inhibition of T-Type Calcium Channels

Compelling evidence links amyloid beta (Aβ) peptide accumulation in the brains of Alzheimer's disease (AD) patients with the emergence of learning and memory deficits, yet a clear understanding of the events that drive this synaptic pathology are lacking. We present evidence that neurons exposed to Aβ are unable to form new synapses, resulting in learning deficits in vivo. We demonstrate the Nogo receptor family (NgR1-3) acts as Aβ receptors mediating an inhibition of synapse assembly, plasticity, and learning. Live imaging studies reveal Aβ activates NgRs on the dendritic shaft of neurons, triggering an inhibition of calcium signaling. We define T-type calcium channels as a target of Aβ-NgR signaling, mediating Aβ's inhibitory effects on calcium, synapse assembly, plasticity, and learning. These studies highlight deficits in new synapse assembly as a potential initiator of cognitive pathology in AD, and pinpoint calcium dysregulation mediated by NgRs and T-type channels as key components. VIDEO ABSTRACT.

Pharmacological properties of SAK3, a novel T-type voltage-gated Ca2+ channel enhancer

T-type voltage-gated Ca²⁺ channels (T-VGCCs) function in the pathophysiology of epilepsy, pain and sleep. However, their role in cognitive function remains unclear. We previously reported that the cognitive enhancer ST101, which stimulates T-VGCCs in rat cortical slices, was a potential Alzheimer's disease therapeutic. Here, we introduce a more potent T-VGCC enhancer, SAK3 (ethyl 8'-methyl-2',4-dioxo-2-(piperidin-1-yl)-2'H-spiro[cyclopentane-1,3'-imidazo [1,2-a]pyridin]-2-ene-3-carboxylate), and characterize its pharmacological properties in brain. Based on whole cell patch-clamp analysis, SAK3 (0.01-10 nM) significantly enhanced Cav3.1 currents in neuro2A cells ectopically expressing Cav3.1. SAK3 (0.1-10 nM nM) also enhanced Cav3.3 but not Cav3.2 currents in the transfected cells. Notably, Cav3.1 and Cav3.3 T-VGCCs were localized in cholinergic neurve systems in hippocampus and in the medial septum. Indeed, acute oral administration of SAK3 (0.5 mg/kg, p.o.), but not ST101 (0.5 mg/kg, p.o.) significantly enhanced acetylcholine (ACh) release in the hippocampal CA1 region of naïve mice. Moreover, acute SAK3 (0.5 mg/kg, p.o.) administration significantly enhanced hippocampal ACh levels in olfactory-bulbectomized (OBX) mice, rescuing impaired memory-related behaviors. Treatment of OBX mice with the T-VGCC-specific blocker NNC 55-0396 (12.5 mg/kg, i.p.) antagonized both enhanced ACh release and memory improvements elicited by SAK3 administration. We also observed that SAK3-induced ACh releases were significantly blocked in the hippocampus from Cav3.1 knockout (KO) mice. These findings suggest overall that T-VGCCs play a key role in cognition by enhancing hippocampal ACh release and that the cognitive enhancer SAK3 could be a candidate therapeutic in Alzheimer's disease.

Effects of equol on deoxycorticosterone acetate salt-induced hypertension and associated vascular dementia in rats

Oxidative stress is the major cause of neuronal cell degeneration observed in neurodegenerative diseases including vascular dementia (VaD), and hypertension has been found to increase the probability of VaD. Here, we investigated the effects of equol in deoxycorticosterone acetate (DOCA)-salt-induced hypertensive rats (DHRs) and the associated VaD. The systolic blood pressure of rats treated with low- (10 mg per kg body weight) and high-dose (20 mg per kg body weight) equol for 4 weeks was lower than that of the control group by 12.18 and 17.48% in a dose-dependent manner, respectively (p < 0.05), which was regulated by inhibiting angiotensin-converting enzyme (ACE) activity and increasing the nitric oxide (NO) production. Equol-treated DHRs showed a significant decrease in both the swimming distance and time required to reach the escape platform (78.20 to 82.56%, p < 0.05). In addition, the probe trial session and working memory test indicated that equol improved the long- and short-term memory of the rats. Moreover, the brain antioxidant activity was increased by elevating the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) levels, and the malondialdehyde (MDA) content and acetylcholinesterase (AChE) activity were decreased, indicating that equol suppressed oxidative stress. In conclusion, we demonstrated that equol exhibited comparable blood pressure (BP)-lowering and VaD-improving effects with the clinically used drug, lisinopril in DHRs while there was a positive correlation between the doses. Therefore, this bioactive compound may be useful for developing functional foods, thereby extending the application of equol-containing crops.

Effects of the Acetylcholine Release Agent ST101 with Donepezil in Alzheimer's Disease: A Randomized Phase 2 Study

BACKGROUND AND OBJECTIVE

ST101, an acetylcholine release agent with efficacy in rodent memory and cognition models, was assessed for clinical safety and efficacy.

METHODS

A phase 2 double blind, placebo-controlled study enrolled 210 AD patients (MMSE 10-20) on 10 mg donepezil QD. Patients received ST101 (10, 60, or 120 mg QD) or placebo for 12 weeks. The primary endpoint was change in cognitive function measured by ADAS-cog in the modified Intent To Treat (MITT) population and the Per Protocol (PP) population.

RESULTS

Mean ADAS-cog change favored ST101 over placebo in the MITT population (p = 0.0957, one-sided) and in the PP population (p = 0.0434, one-sided, ∼1.5 point drug-placebo difference) comparing all ST101 dose groups combined to placebo. Among secondary and exploratory outcome measures the ADCS-CGIC also showed a beneficial trend (p = 0.0294, one-sided). In a post-hoc analysis, the subgroup with more severe disease (MMSE 10-17) showed a dose response in the ADAS-cog with the greatest efficacy at 120 mg (p = 0.0067, one sided). No significant ST101-related safety concerns were identified.

CONCLUSION

The study supports the possibility that ST101, in patients receiving a stable dose of donepezil, may provide additional symptomatic benefit in moderate AD.

Effects of Lactobacillus plantarum TWK10-Fermented Soymilk on Deoxycorticosterone Acetate-Salt-Induced Hypertension and Associated Dementia in Rats

Oxidative stress resulting from excessive production of reactive oxygen species is the major mediator of neuronal cell degeneration observed in neurodegenerative diseases, such as Alzheimer’s disease (AD) and vascular dementia (VaD). Additionally, hypertension has been shown to be a positive risk factor for VaD. Therefore, the objective of this study was to investigate the effects of Lactobacillus plantarum strain TWK10 (TWK10)-fermented soymilk on the protection of PC-12 cells in H₂O₂-, oxygen-glucose deprivation (OGD)- and deoxycorticosterone acetate (DOCA)-salt-induced rat models of VaD. Notably, the viabilities of H₂O₂-treated PC-12 cells and OGD model were significantly increased by treatment with TWK10-fermented soymilk ethanol extract (p < 0.05). In addition, oral administration of TWK10-fermented soymilk extract in DOCA-salt hypertension-induced VaD rats resulted in a significant decrease in blood pressure (p < 0.05), which was regulated by inhibiting ACE activity and promoting NO production, in addition to decreased escape latency and increased target crossing (p < 0.05). In conclusion, these results demonstrated that TWK10-fermented soymilk extract could improve learning and memory in DOCA-salt hypertension-induced VaD rats by acting as a blood pressure-lowering and neuroprotective agent.

Potentiation of Acetylcholine-Mediated Facilitation of Inhibitory Synaptic Transmission by an Azaindolizione Derivative, ZSET1446 (ST101), in the Rat Hippocampus

The integrity of the hippocampal network depends on the coordination of excitatory and inhibitory signaling, which are under dynamic control by various regulatory influences such as the cholinergic systems. ZSET1446 (ST101; spiro[imidazo[1,2-a]pyridine-3,2-indan]-2(3H)-one) is a newly synthesized azaindolizinone derivative that significantly improves learning deficits in various types of Alzheimer disease (AD) models in rats. We examined the effect of ZSET1446 on the nicotinic acetylcholine (ACh) receptor (nAChR)-mediated regulation of synaptic transmission in hippocampal slices of rats. ZSET1446 significantly potentiated the facilitatory effect of nicotine and ACh on the frequency of spontaneous postsynaptic currents (sPSCs) recorded in CA1 pyramidal neurons with a maximum effect at 100 pM (tested range, 10 pM-1000 pM). The basal sPSC frequency without ACh was not affected. Such potentiation by ZSET1446 was observed in both the pharmacologic isolations of inhibitory and excitatory sPSCs and markedly reduced by blockade of either α7 or α4β2 nAChRs. ZSET1446 did not affect ACh-activated inward currents or depolarization of interneurons in the stratum radiatum and the lacunosum moleculare. These results indicate that ZSET1446 potentiates the nicotine-mediated enhancement of synaptic transmission in the hippocampal neurons without affecting nAChRs themselves, providing a novel possible mechanism of procognitive action that might improve learning deficits in clinical therapy.

Amyloid β Enhances Typical Rodent Behavior While It Impairs Contextual Memory Consolidation

Alzheimer's disease (AD) is associated with an early hippocampal dysfunction, which is likely induced by an increase in soluble amyloid beta peptide (Aβ). This hippocampal failure contributes to the initial memory deficits observed both in patients and in AD animal models and possibly to the deterioration in activities of daily living (ADL). One typical rodent behavior that has been proposed as a hippocampus-dependent assessment model of ADL in mice and rats is burrowing. Despite the fact that AD transgenic mice show some evidence of reduced burrowing, it has not been yet determined whether or not Aβ can affect this typical rodent behavior and whether this alteration correlates with the well-known Aβ-induced memory impairment. Thus, the purpose of this study was to test whether or not Aβ affects burrowing while inducing hippocampus-dependent memory impairment. Surprisingly, our results show that intrahippocampal application of Aβ increases burrowing while inducing memory impairment. We consider that this Aβ-induced increase in burrowing might be associated with a mild anxiety state, which was revealed by increased freezing behavior in the open field, and conclude that Aβ-induced hippocampal dysfunction is reflected in the impairment of ADL and memory, through mechanisms yet to be determined.

A viral vector expressing hypoxia-inducible factor 1 alpha inhibits hippocampal neuronal apoptosis

Hypoxia-inducible factor 1 (HIF-1) attenuates amyloid-beta protein neurotoxicity and decreases apoptosis induced by oxidative stress or hypoxia in cortical neurons. In this study, we constructed a recombinant adeno-associated virus (rAAV) vector expressing the human HIF-1α gene (rAAV-HIF-1α), and tested the assumption that rAAV-HIF-1α represses hippocampal neuronal apoptosis induced by amyloid-beta protein. Our results confirmed that rAAV-HIF-1α significantly reduces apoptosis induced by amyloid-beta protein in primary cultured hippocampal neurons. Direct intracerebral rAAV-HIF-1α administration also induced robust and prolonged HIF-1α production in rat hippocampus. Single rAAV-HIF-1α administration resulted in decreased apoptosis of hippocampal neurons in an Alzheimer's disease rat model established by intracerebroventricular injection of aggregated amyloid-beta protein (25-35). Our in vitro and in vivo findings demonstrate that HIF-1 has potential for attenuating hippocampal neuronal apoptosis induced by amyloid-beta protein, and provides experimental support for treatment of neurodegenerative diseases using gene therapy.

Fumanjian, a Classic Chinese Herbal Formula, Can Ameliorate the Impairment of Spatial Learning and Memory through Apoptotic Signaling Pathway in the Hippocampus of Rats with Aβ 1-40 -Induced Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia and lacks disease-altering treatments. Fumanjian (FMJ), a famous classic Chinese herbal prescription for dementia, was first recorded in the Complete Works of Jingyue during the Ming Dynasty. This study aimed to investigate whether FMJ could prevent cognitive deficit and take neuroprotective effects in Aβ 1-40-induced rat model through apoptotic signaling pathway. AD model was established by bilateral injection of Aβ 1-40 into hippocampus in rat. All rats were tested for their capabilities of spatial navigation and memorization by Morris water maze. Apoptosis was tested using TUNEL staining in hippocampus neuronal cells; RT-PCR tested expression of Bcl-2 and Bax mRNA; western blotting tested protein level of cleaved caspase-3. After 14 days of treatment, FMJ significantly improved the escape latency and enhanced platform-cross number compared with the Aβ 1-40-injected group (P < 0.05 or P < 0.01). FMJ also significantly decreased number of TUNEL-positive neuronal apoptosis and the expressions of Bax and cleaved Caspase-3 and increased the expression of Bcl-2 (P < 0.01) compared with AD model group. In conclusion, FMJ exerts a protective effect against Aβ 1-40-induced learning and memory deficits and neuronal apoptosis, suggesting that FMJ could be used as a potential therapeutic formula for AD.

7.0T nuclear magnetic resonance evaluation of the amyloid beta (1-40) animal model of Alzheimer's disease: comparison of cytology verification

3.0T magnetic resonance spectroscopic imaging is a commonly used method in the research of brain function in Alzheimer's disease. However, the role of 7.0T high-field magnetic resonance spectroscopic imaging in brain function of Alzheimer's disease remains unclear. In this study, 7.0T magnetic resonance spectroscopy showed that in the hippocampus of Alzheimer's disease rats, the N-acetylaspartate wave crest was reduced, and the creatine and choline wave crest was elevated. This finding was further supported by hematoxylin-eosin staining, which showed a loss of hippocampal neurons and more glial cells. Moreover, electron microscopy showed neuronal shrinkage and mitochondrial rupture, and scanning electron microscopy revealed small size hippocampal synaptic vesicles, incomplete synaptic structure, and reduced number. Overall, the results revealed that 7.0T high-field nuclear magnetic resonance spectroscopy detected the lesions and functional changes in hippocampal neurons of Alzheimer's disease rats in vivo, allowing the possibility for assessing the success rate and grading of the amyloid beta (1-40) animal model of Alzheimer's disease.

Asn-Trp dipeptides improve the oxidative stress and learning dysfunctions ind-galactose-induced BALB/c mice

Asn-Trp (NW) interventions for 4 weeks can attenuate the oxidative stress and learning dysfunctions induced by dailyd-galactose subcutaneous injection for 8 weeks.

Calcium channelopathies and Alzheimer's disease: insight into therapeutic success and failures

Calcium ions are versatile and universal biological signaling factors that regulate numerous cellular processes ranging from cell fertilization, to neuronal plasticity that underlies learning and memory, to cell death. For these functions to be properly executed, calcium signaling requires precise regulation, and failure of this regulation may tip the scales from a signal for life to a signal for death. Disruptions in calcium channel function can generate complex multi-system disorders collectively referred to as "calciumopathies" that can target essentially any cell type or organ. In this review, we focus on the multifaceted involvement of calcium signaling in the pathophysiology of Alzheimer's disease (AD), and summarize the various therapeutic options currently available to combat this disease. Detailing the series of disappointing AD clinical trial results on cognitive outcomes, we emphasize the urgency to design alternative therapeutic strategies if synaptic and memory functions are to be preserved. One such approach is to target early calcium channelopathies centrally linked to AD pathogenesis.

Hydrogen sulfide protects against amyloid beta-peptide induced neuronal injury via attenuating inflammatory responses in a rat model

Neuroinflammation has been recognized to play a critical role in the pathogenesis of Alzheimer's disease (AD), which is pathologically characterized by the accumulation of senile plaques containing activated microglia and amyloid β-peptides (Aβ). In the present study, we examined the neuroprotective effects of hydrogen sulfide (H2S) on neuroinflammation in rats with Aβ1-40 hippocampal injection. We found that Aβ-induced rats exhibited a disorder of pyramidal cell layer arrangement, and a decrease of mean pyramidal cell number in the CA1 hippocampal region compared with those in sham operated rats. NaHS (a donor of H2S, 5.6 mg/kg/d, i.p.) treatment for 3 weeks rescued neuronal cell death significantly. Moreover, we found that H2S dramatically suppressed the release of TNF-α, IL-1β and IL-6 in the hippocampus. Consistently, both immunohistochemistry and Western blotting assays showed that H2S inhibited the upregulation of COX-2 and the activation of NF-κB in the hippocampus. In conclusion, our data indicate that H2S suppresses neuroinflammation via inhibition of the NF-κB activation pathway in the Aβ-induced rat model and has potential value for AD therapy.

IL-6 attenuates trimethyltin-induced cognitive dysfunction via activation of JAK2/STAT3, M1 mAChR and ERK signaling network

We previously reported that interleukin (IL)-6 deficiency potentiates trimethyltin (TMT)-induced convulsive neurotoxicity. The purpose in this study was to investigate the molecular mechanism by which cytokines affect TMT-induced cognitive impairment. To accomplish this, we examined hippocampal changes in Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling in relation to cholinergic parameters after TMT treatment in mice genetically deficient in IL-6 (IL-6(-/-)), tumor necrosis factor-α (TNF-α(-/-)), or interferon-γ (IFN-γ(-/-)). The IL-6(-/-) mice were the most susceptible to TMT-induced cognitive dysfunction and exhibited significant decreases in JAK2/STAT3 signaling and M1 muscarinic acetylcholine receptor (mAChR) expression, as well as other cholinergic parameters, compared with wild-type (WT) animals. Recombinant IL-6 protein (rIL-6) significantly attenuated these impairments in TMT-treated IL-6(-/-) mice, whereas an IL-6 receptor antibody potentiated these impairments in TMT-treated WT animals. Inhibition of JAK2 with AG490 or inhibition of cholinergic signaling with the M1 mAChR antagonist dicyclomine counteracted the attenuating effects of rIL-6 on phosphorylated extracellular signal-regulated kinase (ERK) expression, or on cognitive impairment in TMT-treated IL-6(-/-) mice. However, neither AG490 nor dicyclomine significantly attenuated effects of rIL-6 on acetylcholinesterase values. Our results suggest that activation of JAK2/STAT3 signaling and upregulation of the M1 mAChR are essential components of IL-6-mediated memory improvement against TMT toxicity.

Novel cognitive enhancer ST101 enhances acetylcholine release in mouse dorsal hippocampus through T-type voltage-gated calcium channel stimulation

We recently developed a novel cognitive enhancer, ST101 (spiro[imidazo[1,2-a]pyridine-3,2-indan]-2(3H)-one), that activates T-type voltage-gated calcium channels (VGCCs). Here, we address whether T-type VGCC activation with ST101 mediates its cognitive effects in vivo and the relevance of T-type VGCC activation to acetylcholine (ACh) release in the hippocampus. Acute intraperitoneal administration of ST101 (1 mg/kg, i.p.) improved memory-related behaviors in both olfactory bulbectomized (OBX) and scopolamine-treated mice. Effects of ST101 administration were abolished by both intraperitoneal and intracerebroventricular pre-administration of the T-type VGCC inhibitor mibefradil. Acute administration of ST101 enhanced basal and nicotine-induced ACh release in the dorsal hippocampus in both OBX and sham-treated mice. Enhanced ACh release was abolished by infusion with mibefradil (10 μM) but not with the L-type VGCC inhibitor nifedipine (10 μM). As expected, significantly reduced CaMKIIα, PKCα, and ERK phosphorylation was restored by acute ST101 administration in the OBX mouse hippocampal CA1 region. Enhancement of CaMKIIα and PKCα but not ERK phosphorylation was inhibited by mibefradil (20 mg/kg, i.p.) preadministration. Increased CaMKIIα and PKCα phosphorylation was confirmed by increased phosphorylation of GluR1, synapsin I, and NR1. Taken together, stimulation of T-type VGCCs is critical for the enhanced hippocampal ACh release and improved cognitive function seen following ST101 administration.

Hydrogen sulfide attenuates spatial memory impairment and hippocampal neuroinflammation in β-amyloid rat model of Alzheimer's disease

Background

Endogenously produced hydrogen sulfide (H₂S) may have multiple functions in brain. An increasing number of studies have demonstrated its anti-inflammatory effects. In the present study, we investigated the effect of sodium hydrosulfide (NaHS, a H₂S donor) on cognitive impairment and neuroinflammatory changes induced by injections of Amyloid-β_1-40 (Aβ_1-40), and explored possible mechanisms of action.

Methods

We injected Aβ_1-40 into the hippocampus of rats to mimic rat model of Alzheimer’s disease (AD). Morris water maze was used to detect the cognitive function. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay was performed to detect neuronal apoptosis. Immunohistochemistry analyzed the response of glia. The expression of interleukin (IL)-1β and tumor necrosis factor (TNF)-α was measured by enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qRT-PCR). The expression of Aβ_1-40, phospho-p38 mitogen-activated protein kinase (MAPK), phospho-p65 Nuclear factor (NF)-κB, and phospho-c-Jun N-terminal Kinase (JNK) was analyzed by western blot.

Results

We demonstrated that pretreatment with NaHS ameliorated learning and memory deficits in an Aβ_1-40 rat model of AD. NaHS treatment suppressed Aβ_1-40-induced apoptosis in the CA1 subfield of the hippocampus. Moreover, the over-expression in IL-1β and TNF-α as well as the extensive astrogliosis and microgliosis in the hippocampus induced by Aβ_1-40 were significantly reduced following administration of NaHS. Concomitantly, treatment with NaHS alleviated the levels of p38 MAPK and p65 NF-κB phosphorylation but not JNK phosphorylation that occurred in the Aβ_1-40-injected hippocampus.

Conclusions

These results indicate that NaHS could significantly ameliorate Aβ_1-40-induced spatial learning and memory impairment, apoptosis, and neuroinflammation at least in part via the inhibition of p38 MAPK and p65 NF-κB activity, suggesting that administration of NaHS could provide a therapeutic approach for AD.

Scutellarin protects against Aβ-induced learning and memory deficits in rats: involvement of nicotinic acetylcholine receptors and cholinesterase

AIM

To examine the protective effects of scutellarin (Scu) on rats with learning and memory deficit induced by β-amyloid peptide (Aβ).

METHODS

Fifty male Wistar rats were randomly divided into 5 groups: control, sham operation, Aβ, Aβ+Scu, and Aβ+piracetam groups. Aβ(25-35) was injected into the lateral ventricle (10 μg each side). Scu (10 mg/2 mL) or piracetam (10 mg/2 mL was intragastrically administered per day for 20 consecutive days following Aβ treatment. Learning and memory was assessed with Morris water maze test. The protein and mRNA levels of nicotinic acetylcholine receptor (nAChR) α4, α7, and β2 subunits in the brain were examined using Western blotting and real-time PCR, respectively. The activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in the brain and plasma were measured using Ellman's colorimetric method.

RESULTS

In Aβ group, the escape latency period and first platform cross was significantly increased, and the total number of platform crossings was significantly decreased, as compared with the control and the sham operation groups. Both Scu and piracetam treatment significantly reduced the escape latency period and time to cross platform, and increased the number of platform crosses, but there were no significant differences between Aβ+Scu and Aβ+piracetam groups. In Aβ group, the protein levels of nAChR α4 and α7 subunits in the cerebral cortex were significantly decreased by 42%-47% and 58%-61%, respectively, as compared to the control and the sham operation groups. Scu treatment caused upregulation of α4 and α7 subunit proteins by around 24% and 30%, respectively, as compared to Aβ group, but there were no significant differences between Aβ+Scu and Aβ+piracetam groups. The protein level of nAChR β2 subunit had no significant difference among different groups. The mRNA levels of nAChR α4, α7, and β2 subunits were not significantly changed. In Aβ group, the activities of AChE and BuChE in the brain were significantly increased, but were significantly decreased in the plasma, as compared to the control and the sham operation groups. Scu or piracetam treatment restored the activities in brain and plasma nearly to the levels in the control group.

CONCLUSION

The results suggest that Scu may rescue some of the deleterious effects of Aβ, possibly by stimulating nAChR protein translation and regulating cholinesterase activity.

Behavioural and cellular effects of exogenous amyloid-β peptides in rodents

A better understanding of Alzheimer's disease (AD) and the development of disease modifying therapies are some of the biggest challenges of the 21st century. One of the core features of AD are amyloid plaques composed of amyloid-beta (Aβ) peptides. The first hypothesis proposed that cognitive deficits are linked to plaque-development and transgenic mice have been generated to study this link, thereby providing a good model to develop new therapeutic approaches. Since later it was recognised that in AD patients the cognitive deficit is rather correlated to soluble amyloid levels, consequently, a new hypothesis appeared associating the earliest amyloid toxicity to these soluble species. The purpose of this review is to give a summary of behavioural and cellular data obtained after soluble Aβ peptide administration into rodents' brain, thereby showing that this model is a valid tool to investigate AD pathology when no plaques are present. Additionally, this method offers an excellent, efficient model to test compounds which could act at such early stages of the disease.

Red mold fermented products and Alzheimer's disease: a review

Alzheimer's disease is seen mainly in individuals over the age of 65, and the morbidity rate increases with age. Regarding the health function of Monascus-fermented red mold rice (RMR), besides hypolipidemic and hypotensive effects, other health functions of RMR such as anti-oxidation, cancer prevention, anti-fatigue, and anti-obesity have also been reported. Many published studies have shown the efficacy of RMR in the prevention of Alzheimer's disease. The current article discusses and provides evidence to support the beneficial potential of RMR in the prevention of Alzheimer's disease by discussing the pathogenic factors of Alzheimer's disease and the secondary metabolites of Monascus.

ST101 induces a novel 17 kDa APP cleavage that precludes Aβ generation in vivo

OBJECTIVE

Inhibiting Aβ generation is a prime therapeutic goal for preventing or treating Alzheimer disease. Here we sought to identify any disease-modifying properties of an azaindolizinone derivative, spiro[imidazo[1,2-a]pyridine-3,2-idan]-2(3H)-one (ST101 or ZSET1446).

METHODS

The effects of ST101 were studied in 3xTg-AD mice and young cynomolgus monkeys using a combination of biochemical and histological analyses.

RESULTS

Here we describe that ST101 induces cleavage of APP protein at a novel site, generating a 17 kDa C-terminal fragment. This 17 kDa APP cleavage product does not appear to be a substrate for either α- or β-secretase, and thus bypasses generation of Aβ. ST101 is orally active, efficacious at low doses, improves memory function, and robustly reduces brain Aβ in transgenic mice and nonhuman primates.

INTERPRETATION

Using rodent and nonhuman primate models, we show that ST101 represents a novel class of small molecules that reduce central nervous system levels of Aβ by inducing an alternate pathway of APP cleavage.

Inhibition of phosphodiesterase-4 reverses memory deficits produced by Aβ25-35 or Aβ1-40 peptide in rats

RATIONALE

Cyclic AMP signaling plays an important role in memory loss associated with Alzheimer's disease (AD). However, little is known about whether inhibition of phosphodiesterase-4 (PDE4), which increases intracellular cAMP, reverses β-amyloid peptide (Aβ)-induced memory deficits.

OBJECTIVE

Experiments were performed to demonstrate the effect of the PDE4 inhibitor rolipram on memory impairment produced by Aβ1-40 (Aβ40) or its core fragment Aβ25-35.

METHODS

We tested memory using Morris water-maze and passive avoidance tasks and examined expression of phosphorylated cAMP response-element binding protein (pCREB) in the hippocampus in rats treated with Aβ25-35 or Aβ40 into bilateral CA1 subregions, with or without rolipram administration.

RESULTS

Aβ25-35 (10 μg/side) increased escape latency during acquisition training and decreased swimming time and distance in the target quadrant in the water-maze probe trial; it also decreased 24-h retention in the passive avoidance paradigm. All these were reversed by chronic administration of rolipram (0.5 mg/kg). Similarly, Aβ40 (4 μg/side) produced memory impairment, as demonstrated by decreased retention in passive avoidance; this was also reversed by repeated treatment with rolipram. In addition, rolipram blocked extinction of memory during the 32-day testing period in the passive avoidance test. Further, Aβ40 decreased pCREB expression in the hippocampus, which was also reversed by rolipram; the changes in pCREB were highly correlated with those in memory.

CONCLUSIONS

These results suggest that the PDE4 inhibitor rolipram reverses cognitive deficits associated with AD most likely via increased cAMP/CREB signaling in the hippocampus; PDE4 could be a target for drugs that improve cognition in AD.

A novel cognitive enhancer, ZSET1446/ST101, promotes hippocampal neurogenesis and ameliorates depressive behavior in olfactory bulbectomized mice

In the adult brain, neurogenesis persistently occurs in the subgranular zone of the hippocampal dentate gyrus (DG), and impaired neurogenesis is implicated in depressive behaviors and poor learning memory. Here, we investigated the effects of oral administration of spiro[imidazo[1,2-a]pyridine-3,2-indan]-2(3H)-one (ZSET1446/ST101), a novel cognitive enhancer stimulating acetylcholine release, on adult neurogenesis in olfactory bulbectomized (OBX) mice. OBX mice showed significant decreases in the number of newborn cells in the DG by immunohistochemical analysis of 5-bromo-2-deoxyuridine incorporation. Impaired neurogenesis observed in OBX mice was significantly improved by chronic administration with ZSET1446. We confirmed that administration with mecamylamine, a nicotinic acetylcholine receptor antagonist, inhibits ZSET1446-enhanced neurogenesis in the DG. ZSET1446 administration also restored decreased phosphorylation of Akt and extracellular signal-regulated kinase in the DG of OBX mice. Consistent with restored neurogenesis, chronic but not single ZSET1446 administration promoted significant decreases in immobility in tail suspension tests and improved cognitive behaviors in OBX mice. Taken together, chronic ZSET1446 administration antagonized impaired neurogenesis seen in OBX mice, an effect closely associated with improvement of depressive behavior.

Red mold rice promoted antioxidase activity against oxidative injury and improved the memory ability of zinc-deficient rats

Zn deficiency is a common disease leading to memory impairment with increasing age. This study evaluated the protection effects of red mold rice (RMR) administration and Zn supplementation against memory and learning ability impairments from oxidative stress caused by Zn deficiency. Rats (4 weeks old) were induced to be Zn deficiency by a Zn-deficient diet for 12 weeks. After that, rats were administered Zn, 1xRMR, 5xRMR, and various dosages of RMR plus Zn, respectively. Decreases of antioxidant enzyme activities in the hippocampus and cortex were observed, and the levels of Ca, Fe, and Mg were increased in the hippocampus and cortex of Zn-deficient rats, leading to memory and learning ability injury. However, the administration of RMR (1- or 5-fold dosage) and with or without Zn significantly improved the antioxidase and neural activity to maintain cortex and hippocampus functions. This study demonstrates that RMR is a possible functional food for the prevention or cure of neural injury associated with Zn deficiency.

Protective effect of stilbenes containing extract-fraction from Cajanus cajan L. on Abeta(25-35)-induced cognitive deficits in mice

Cajanus cajan (L.) is a traditional Chinese herb medicine which contains a lot of potential active components. In the present study, we identified the effects of the stilbenes containing extract-fraction from C. cajan L. (sECC) on Abeta(25-35)-induced cognitive deficits, oxidative stress and cholinergic dysfunction in mice. Mice were treated with sECC (100 and 200mg/kg/d) for 1-week, and then received a single intracerebroventricular (i.c.v.) injection of Abeta(25-35) (5mug/mice). Behavioral changes and neuron apoptosis in mice were evaluated using Morris water maze and TUNEL tests. Furthermore, superoxide dismutase (SOD), choline acetyl transferase (ChAT) and acetylcholine esterase (AchE) activity in hippocampus and cortex were analyzed by spectrophotometric method. The data showed that consumption of sECC (200mg/kg) significantly ameliorated the cognitive deficits and neuron apoptosis caused by i.c.v. injection of Abeta(25-35). At the same time, the decreased SOD and ChAT activity in hippocampus and cortex were markedly increased by sECC (200mg/kg). sECC has no effect on AchE activity in hippocampus and cortex. These findings suggest that sECC may be a potential candidate for the development of therapeutic agents to manage cognitive impairment associated with Alzheimer's disease (AD) through increasing the activity of ChAT and anti-oxidative mechanism.