Therapeutic efficacy of novel memantine nitrate MN-08 in animal models of Alzheimer's disease.

Alzheimer's disease (AD) is a leading cause of dementia in elderly individuals and therapeutic options for AD are very limited. Over-activation of N-methyl-D-aspartate (NMDA) receptors, amyloid ß (Aß) aggregation, a decrease in cerebral blood flow (CBF), and downstream pathological events play important roles in the disease progression of AD. In the present study, MN-08, a novel memantine nitrate, was found to inhibit Aß accumulation, prevent neuronal and dendritic spine loss, and consequently attenuate cognitive deficits in 2-month-old APP/PS1 transgenic mice (for a 6-month preventative course) and in the 8-month-old triple-transgenic (3×Tg-AD) mice (for a 4-month therapeutic course). In vitro, MN-08 could bind to and antagonize NMDA receptors, inhibit the calcium influx, and reverse the dysregulations of ERK and PI3K/Akt/GSK3ß pathway, subsequently preventing glutamate-induced neuronal loss. In addition, MN-08 had favorable pharmacokinetics, blood-brain barrier penetration, and safety profiles in rats and beagle dogs. These findings suggest that the novel memantine nitrate MN-08 may be a useful therapeutic agent for AD.

Shexiang Baoxin Pill, a Traditional Chinese Herbal Formula, Rescues the Cognitive Impairments in APP/PS1 Transgenic Mice.

BACKGROUND: Shexiang Baoxin Pill (SBP), a formulated traditional Chinese medicine (TCM), has been widely used to treat cardiovascular diseases for years. This herbal mixture has been shown to promote differentiation of cultured neuronal cells. Here, we aimed to investigate the effects of SBP in attenuating cognitive impairment in APP/PS1 transgenic mice. METHODS: Ethanol and water extracts of SBP, denoted as SBPEtOH and SBPwater, were standardized and applied onto cultured rat pheochromocytoma PC12 cells. The potential effect of SBPEtOH extract in attenuating the cognitive impairments in APP/PS1 transgenic mice was shown by following lines of evidence: (i) inhibition of Aß fibril formation, (ii) suppression of secretions of cytokines, and (iii) improvement of behavioral tests by Morris water maze. RESULTS: SBPwater and SBPEtOH inhibited the formation of ß-amyloid fibrils and protected the Aß-induced cytotoxicity in cultured PC12 cells. In APP/PS1 transgenic mice, the treatment of SBPEtOH inhibited expressions of NO, NOS, AChE, as well as aggregation of Aß. Besides, the levels of pro-inflammatory cytokines were suppressed by SBP treatment in the transgenic mice. Importantly, the behavioral tests by Morris Water maze indicated that SBP attenuated cognitive impairments in APP/PS1 transgenic mice. CONCLUSION: The current result has supported the notion that SPB might ameliorate the cognitive impairment through multiple targets, suggesting that SBP could be considered as a promising anti-AD agent.

Association between osteoarthritis and increased risk of dementia: A systemic review and meta-analysis.

OBJECTIVE: To investigate the possible association between osteoarthritis (OA) and the risk of dementia. METHODS: Cohort, case-control, and cross-sectional studies were obtained from wide literature search up to 20 April 2018 from following electronic databases: PubMed, Embase, Cochrane, using the MeSH terms: "osteoarthritis" AND "dementia". The literature search was then expanded to congress abstracts. After screening and selection of relevant studies by two investigators, data was extracted. Estimates were then calculated using a random-effect size model. Sensitivity-analysis was conducted for gender and age adjusted studies and pooled for studies with STROBE quality assessment score ≥75%. Publication bias was assessed by Funnel plot. Analyses were performed using Data Analysis and Statistical Software Version 14.2. RESULTS: Nearly 1549 publication references were initially retrieved. Twenty-six publications were checked with full-text. Six observational studies with 388,252 individuals were included. OA was associated with a significantly increased risk for dementia (OR = 1.20; 95% confidence interval (CI), 1.03-1.39, I = 95.6%, P < .05). After pooling the studies with adjustment of age and gender, the risk increased (OR 1.36; 95% CI, 1.22-1.51, I = 75.6%, P < .0001). After pooling the study with a STROBE Quality score ≥75% the risk for dementia was slightly increased (OR 1.33; 95% CI, 1.17-1.5, I = 93.5%, p < 0.0001). CONCLUSIONS: There is an association between osteoarthritis and the risk of dementia. This meta-analysis does not provide causality. Further prospective cohort studies are needed to clarify, if knee-, hip-, or hand-OA are independent risk factors for Alzheimer's disease and vascular dementia.

Tacrine(10)-hupyridone, a dual-binding acetylcholinesterase inhibitor, potently attenuates scopolamine-induced impairments of cognition in mice.

Tacrine(10)-hupyridone (A10E) was designed as a dual-binding acetylcholinesterase (AChE) inhibitor from the modification of tacrine and a fragment of huperzine A. We have found that A10E effectively inhibited AChE in a mixed competitive manner, with an IC50 of 26.4 nM, which is more potent than those of tacrine and huperzine A. Most importantly, we have shown, for the first time that A10E attenuated scopolamine-induced cognitive impairments without affecting motor function in mice. A10E effectively attenuated impairments of learning and memory to a similar extent as donepezil, an inhibitor of AChE used for treating Alzheimer's disease (AD). In addition, A10E significantly decreased AChE activity in the brain of mice, suggesting that A10E might cross the brain blood-barrier. Taken together, our results demonstrated that A10E, a designed dual-binding AChE inhibitor, could effectively reverse cognitive impairments, indicating that A10E might provide therapeutic efficacy for AD treatment.

No synergism between bis(propyl)-cognitin and rasagiline on protecting dopaminergic neurons in Parkinson's disease mice.

Rasagiline, a monoamine oxidase-B inhibitor, and bis(propyl)-cognitin (B3C), a novel dimer are reported to be neuroprotective. Herein, the synergistical neuroprotection produced by rasagiline and B3C was investigated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mice of Parkinsonism. By using neurobehavioural tests, high-performance liquid chromatography and western blot assay, we showed that B3C at 0.3 mg/kg, rasagiline at 0.02 mg/kg, as well as co-treatment with B3C and rasagiline prevented MPTP-induced behavioural abnormities, increased the concentrations of dopamine and its metabolites in the striatum, and up-regulated the expression of tyrosine hydroxylase in the substantia nigra. However, the neuroprotective effects of co-treatment were not significantly improved when compared with those of B3C or rasagiline alone. Collectively, we have demonstrated that B3C at 0.3 mg/kg and rasagline at 0.02 mg/kg could not produce synergistic neuroprotective effects.

Dimeric bis (heptyl)-Cognitin Blocks Alzheimer's ß-Amyloid Neurotoxicity Via the Inhibition of Aß Fibrils Formation and Disaggregation of Preformed Fibrils.

AIMS: Fibrillar aggregates of ß-amyloid protein (Aß) are the main constituent of senile plaques and considered to be one of the causative events in the pathogenesis of Alzheimer's disease (AD). Compounds that could inhibit Aß fibrils formation, disaggregate preformed Aß fibrils as well as reduce their associated neurotoxicity might have therapeutic values for treating AD. In this study, the inhibitory effects of bis (heptyl)-cognitin (B7C), a multifunctional dimer derived from tacrine, on aggregation and neurotoxicity of Aß1-40 were evaluated both in vitro and in vivo. METHODS: Thioflavin T fluorescence assay was carried out to evaluate Aß aggregation, MTT and Hoechst-staining assays were performed to investigate Aß-associated neurotoxicity. Fluorescent probe DCFH-DA was used to estimate the accumulation of intracellular reactive oxygen stress (ROS). Morris water maze was applied to determine learning and memory deficits induced by intracerebroventricular infusion of Aß in rats. RESULTS: B7C (0.1-10 µM), but not tacrine, effectively inhibited Aß fibrils formation and disaggregated preformed Aß fibrils following co-incubation of B7C and Aß monomers or preformed fibrils, respectively. In addition, B7C markedly reduced Aß fibrils-associated neurotoxicity in SH-SY5Y cell line, as evidenced by the increase in cell survival, the decrease in Hoechst-stained nuclei and in intracellular ROS. Most encouragingly, B7C (0.1 and 0.2 mg/kg), 10 times more potently than tacrine (1 and 2 mg/kg), inhibited memory impairments after intracerebroventricular infusion of Aß in rats, as evidenced by the decrease in escape latency and the increase in the spatial bias in Morris water maze test along with upregulation of choline acetyltransferase activity and downregulation of acetylcholinesterase activity. CONCLUSION: These findings provide not only novel molecular insight into the potential application of B7C in treating AD, but also an effective approach for screening anti-AD agents.

Robust Neuritogenesis-Promoting Activity by Bis(heptyl)-Cognitin Through the Activation of alpha7-Nicotinic Acetylcholine Receptor/ERK Pathway.

AIMS: Neurodegenerative disorders are caused by progressive neuronal loss in the brain, and hence, compounds that could promote neuritogenesis may have therapeutic values. In this study, the effects of bis(heptyl)-cognitin (B7C), a multifunctional dimer, on neurite outgrowth were investigated in both PC12 cells and primary cortical neurons. METHODS: Immunocytochemical staining was used to evaluate the proneuritogenesis effects, and Western blot and short hairpin RNA assays were applied to explore the underlying mechanisms. RESULTS: B7C (0.1-0.5 µM) induced robust neurite outgrowth in PC12 cells, as evidenced by the neurite-bearing morphology and upregulation of growth-associated protein-43 expression. In addition, B7C markedly promoted neurite outgrowth in primary cortical neurons as shown by the increase in the length of ß-III-tubulin-positive neurites. Furthermore, B7C rapidly increased ERK phosphorylation. Specific inhibitors of alpha7-nicotinic acetylcholine receptor (α7-nAChR) and MEK, but not those of p38 or JNK, blocked the neurite outgrowth as well as ERK phosphorylation induced by B7C. Most importantly, genetic depletion of α7-nAChR significantly abolished B7C-induced neurite outgrowth in PC12 cells. CONCLUSION: B7C promoted neurite outgrowth through the activation of α7-nAChR/ERK pathway, which offers novel insight into the potential application of B7C in the treatment of neurodegenerative disorders.

Effect of tacrine-3-caffeic acid, a novel multifunctional anti-Alzheimer's dimer, against oxidative-stress-induced cell death in HT22 hippocampal neurons: involvement of Nrf2/HO-1 pathway.

AIMS: Oxidative stress (OS) plays an important role in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD). This study was designed to uncover the cellular and biochemical mechanisms underlying the neuroprotective effects of tacrine-3-caffeic acid (T3CA), a novel promising multifunctional anti-Alzheimer's dimer, against OS-induced neuronal death. METHODS AND RESULTS: T3CA protected HT22 cells against high-concentration-glutamate-induced cell death in time- and concentration-dependent manners and potently attenuated glutamate-induced intracellular reactive oxygen species (ROS) production as well as mitochondrial membrane-potential (ΔΨ) disruption. Besides, T3CA significantly induced nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation and increased its transcriptional activity, which were demonstrated by Western blotting, immunofluorescence, and antioxidant response element (ARE)-luciferase reporter gene assay. Further studies showed that T3CA potently up-regulated heme oxygenase-1 (HO-1), an endogenous antioxidative enzyme and a downstream effector of Nrf2, at both mRNA and protein levels. The neuroprotective effects of T3CA were partially reversed by brusatol, which reduced protein level of Nrf2, or by inhibiting HO-1 with siRNA or ZnPP-IX, a specific inhibitor of HO-1. CONCLUSIONS: Taken together, these results clearly demonstrate that T3CA protects neurons against OS-induced cell death partially through Nrf2/ARE/HO-1 signaling pathway, which further supports that T3CA might be a promising novel therapeutic agent for OS-associated diseases.

Sunitinib produces neuroprotective effect via inhibiting nitric oxide overproduction.

BACKGROUND: Sunitinib is an inhibitor of the multiple receptor tyrosine kinases (RTKs) for cancer therapy. Some sunitinib analogues could prevent neuronal death induced by various neurotoxins. However, the neuroprotective effects of sunitinib have not been reported. METHODS: Cerebellar granule neurons (CGNs) and SH-SY5Y cells were exposed to low-potassium and MPP(+) challenges, respectively. MTT assay, FDA/PI staining, Hoechst staining, DAF-FM, colorimetric nitric oxide synthase (NOS) activity assay, and Western blotting were applied to detect cell viability, NO production, NOS activity, and neuronal NOS (nNOS) expression. Short hairpin RNA was used to decrease nNOS expression. In vitro NOS enzyme activity assay was used to determine the direct inhibition of nNOS by sunitinib. RESULTS: Sunitinib prevented low-potassium-induced neuronal apoptosis in CGNs and MPP(+) -induced neuronal death in SH-SY5Y cells. However, PTK787, another RTK inhibitor, failed to decrease neurotoxicity in the same models. Sunitinib reversed the increase in NO levels, NOS activity, and nNOS expression induced by low potassium or MPP(+) . Knockdown of nNOS expression partially abolished the neuroprotective effects of sunitinib. Moreover, sunitinib directly inhibited nNOS enzyme activity. CONCLUSIONS: Sunitinib exerts its neuroprotective effects by inhibiting NO overproduction, possibly via the inhibition of nNOS activity and the decrease in nNOS expression.

Substantial neuroprotection against K+ deprivation-induced apoptosis in primary cerebellar granule neurons by novel dimer bis(propyl)-cognitin via the activation of VEGFR-2 signaling pathway.

BACKGROUND: Neuronal loss via apoptosis in CNS is the fundamental mechanism underlying various neurodegenerative diseases. Compounds with antiapoptotic property might have therapeutic effects for these diseases. In this study, bis(propyl)-cognitin (B3C), a novel dimer that possesses anti-AChE and anti-N-methyl-d-aspartate receptor activities, was investigated for its neuroprotective effect on K(+) deprivation-induced apoptosis in cerebellar granule neurons (CGNs). METHODS: Cerebellar granule neurons were switched to K(+) deprived medium with or without B3C. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium assay, fluorescein diacetate (FDA)/propidium iodide (PI) staining, Hoechst staining, and DNA laddering assays were applied to detect cytotoxicity and apoptosis. Additionally, the expression of p-VEGFR-2, p-Akt, p-glycogen synthase kinase 3ß (GSK3ß), and p-extracellular signal-regulated kinase (ERK) was examined in CGNs. RESULTS: Switching CGNs to K(+) deprived medium resulted in remarkable apoptosis, which could be substantially blocked by B3C treatment (IC50 , 0.37 µM). Moreover, a rapid decrease in p-Tyr1054-VEGFR-2 was observed after the switch. B3C significantly reversed the inhibition of p-Tyr1054-VEGFR-2 as well as Akt and ERK pathways. VEGFR-2 inhibitor PTK787/ZK222584, as well as PI3-K inhibitor LY294002 and MEK inhibitor PD98059, each abolished the neuroprotective effect of B3C. CONCLUSIONS: Our results demonstrate that B3C blocks K(+) deprivation-induced apoptosis in CGNs through regulating VEGFR-2/Akt/GSK3ß and VEGFR-2/ERK signaling pathways, providing a molecular insight into the therapeutic potential of B3C for the treatment of neurodegenerative diseases.