Therapeutic targets for Alzheimer's disease

Paradoxical effects of feeding status on food consumption and learning performance in zebrafish (Danio rerio)

Associative learning is often studied using food reward as the unconditioned stimulus (US). With warm-blooded species, to get the subject more motivated the solution has been to feed less, making the subject hungrier. Here we show the opposite with zebrafish. We randomly assigned zebrafish to two groups: a once-a-day-fed and a five-times-a-day-fed group, with the same amount of food fed per occasion for fish of both groups, a feeding regimen that lasted for three months. Subsequently, we trained fish by pairing food (US) with a red cue card (the conditioned stimulus, CS), which were placed together in one arm of a plus-maze across eight training sessions. We also ran unpaired training, in which the CS and US were presented in different arms. We found the previously once-a-day-fed zebrafish to consume less food throughout habituation and training sessions compared to the previously five-times-a-day-fed ones. Furthermore, five-times-a-day-fed fish in the paired group swam significantly closer to the CS during a post-training probe trial compared to the five-times-a-day-fed unpaired fish, a paired training effect that was absent in once-a-day-fed fish. Groups did not differ in health or general activity. In sum, elevated chronic feeding improved food consumption and enhanced learning and memory performance without affecting activity levels in adult zebrafish.

LncRNA RP11-59J16.2 aggravates apoptosis and increases tau phosphorylation by targeting MCM2 in AD

Alzheimer’s disease (AD) is a degenerative disease of central nervous system with unclear pathogenesis, accounting for 60%–70% of dementia cases. Long noncoding RNAs (LncRNAs) play an important function in the development of AD. This study aims to explore the role of differentially expressed lncRNAs in AD patients’ serum in the pathogenesis of AD. Microarray analysis was performed in the serum of AD patients and healthy controls to establish lncRNAs and mRNAs expression profiles. GO analysis and KEGG pathway analysis revealed that G₁/S transition of mitotic cell cycle might be involved in the development of AD. The result showed that RP11-59J16.2 was up-regulated and MCM2 was down-regulated in serum of AD patients. SH-SY5Y cells were treated with Aβ 1–42 to establish AD cell model. Dual luciferase reporter gene analysis verified that RP11-59J16.2 could directly interact with 3′UTR of MCM2 and further regulate the expression of MCM2. Inhibition of RP11-59J16.2 or overexpression of MCM2, CCK-8 assay and Annexin V FITC/PI apoptosis assay kit results showed that RP11-59J16.2 could reduce cell viability, aggravate apoptosis and increase Tau phosphorylation in AD cell model by inhibiting MCM2. In short, our study revealed a novel lncRNA RP11-59J16.2 that could promote neuronal apoptosis and increase Tau phosphorylation by regulating MCM2 in AD model, and indicated that lncRNA RP11-59J16.2 might be a potential target molecule for AD development.

Synthesis, in vitro evaluation and molecular docking of a new class of indolylpropyl benzamidopiperazines as dual AChE and SERT ligands for Alzheimer's disease

During the last decade, the one drug-one target strategy has resulted to be inefficient in facing diseases with complex ethiology like Alzheimer's disease and many others. In this context, the multitarget paradigm has emerged as a promising strategy. Based on this consideration, we aim to develop novel molecules as promiscuous ligands acting in two or more targets at the same time. For such purpose, a new series of indolylpropyl-piperazinyl oxoethyl-benzamido piperazines were synthesized and evaluated as multitarget-directed drugs for the serotonin transporter (SERT) and acetylcholinesterase (AChE). The ability to decrease β-amyloid levels as well as cell toxicity of all compounds were also measured. In vitro results showed that at least four compounds displayed promising activity against SERT and AChE. Compounds 18 and 19 (IC₅₀ = 3.4 and 3.6 μM respectively) exhibited AChE inhibition profile in the same order of magnitude as donepezil (DPZ, IC₅₀ = 2.17 μM), also displaying nanomolar affinity in SERT. Moreover, compounds 17 and 24 displayed high SERT affinities (IC₅₀ = 9.2 and 1.9 nM respectively) similar to the antidepressant citalopram, and significant micromolar AChE activity at the same time. All the bioactive compounds showed a low toxicity profile in the range of concentrations studied. Molecular docking allowed us to rationalize the binding mode of the synthesized compounds in both targets. In addition, we also show that compounds 11 and 25 exhibit significant β-amyloid lowering activity in a cell-based assay, 11 (50% inhibition, 10 μM) and 25 (35% inhibition, 10 μM). These results suggest that indolylpropyl benzamidopiperazines based compounds constitute promising leads for a multitargeted approach for Alzheimer's disease.

Callyspongisines A–D: bromopyrrole alkaloids from an Australian marine sponge, Callyspongia sp

An Australian Callyspongia sp. yielded the new bromopyrrole alkaloids callyspongisines A–D. Callyspongisine A is only the second reported example of a natural imino-oxazoline and the first to feature a spiro heterocyclic framework.

Increased heat shock transcription factor 1 in the cerebellum reverses the deficiency of Purkinje cells in Alzheimer's disease

Alzheimer's disease (AD) is one of the most debilitating neurodegenerative nerve diseases, seriously affecting one's ability to carry out daily activities. AD is both progressive and incurable, but molecular studies have begun to shed light on the mechanisms that underlie it. Immunochemical staining showed that cell bodies of Purkinje cells in the cerebellum were significantly reduced in AD rats compared with normal rats. Heat shock protein 70 (HSP70) was found to prevent polyglutamine aggregation in Huntington's disease and spinocerebellar ataxias (SCAs) and to relieve symptoms in SCAs and Parkinson's disease. Recently, AD-related phenotypes were found to be suppressed in HSP70 transgenic rats. However, the effects of other HSPs and the mechanisms of HSP-triggered changes in AD are unknown. In this study, we found that expression levels of HSP60, -70, and -90 were downregulated in the cerebella of rats with AD. Furthermore, heat shock factor 1 (HSF1), a key transcription factor for the expression of HSP genes, was found to be greatly decreased in the cerebella of AD rats. Even more interesting, injection of lentivirus vector-HSF1 into the cerebella of AD rats significantly increased HSF1 and HSP expression levels and induced an increase in the number of Purkinje cell bodies. Our findings provide novel evidence that low expression of HSPs in AD rats is dependent on the low expression of HSF1, and increased expression of HSF1 contributes to the reversal of cerebellar Purkinje cell deficiency in AD. Therefore, increasing HSF1 expression is a potential new strategy for the treatment of AD.

Cognitive function as an emerging treatment target for marijuana addiction

Cannabis is the most widely used illicit substance in the world, and demand for effective treatment is increasing. However, abstinence rates following behavioral therapies have been modest, and there are no effective pharmacotherapies for the treatment of cannabis addiction. We propose a novel research agenda and a potential treatment strategy, based on observations that both acute and chronic exposure to cannabis are associated with dose-related cognitive impairments, most consistently in attention, working memory, verbal learning, and memory functions. These impairments are not completely reversible upon cessation of marijuana use, and moreover may interfere with the treatment of marijuana addiction. Therefore, targeting cognitive impairment associated with chronic marijuana use may be a promising novel strategy for the treatment of marijuana addiction. Preclinical studies suggest that medications enhancing the cholinergic transmission may attenuate cannabis-induced cognitive impairments, but these cognitive enhancing medications have not been examined in controlled human studies. Preliminary evidence from individuals addicted to other drugs suggests that computerized cognitive rehabilitation may also have utility to improve cognitive function in marijuana users. Future clinical studies optimally designed to measure cognitive function as well as drug use behavior would be needed to test the efficacy of these treatments for marijuana addiction.