Explore the vast range of titles available.

At many vertebrate synapses, presynaptic functions are tuned by expression of different Ca v 2 channels. Most invertebrate genomes contain only one Ca v 2 gene. The Drosophila Ca v 2 homolog, cacophony (cac), induces synaptic vesicle release at presynaptic active zones (AZs). We hypothesize that Drosophila cac functional diversity is enhanced by two mutually exclusive exon pairs that are not conserved in vertebrates, one in the voltage sensor and one in the loop binding Ca β and G βγ subunits. We find that alternative splicing in the voltage sensor affects channel activation voltage. Only the isoform with the higher activation voltage localizes to AZs at the glutamatergic Drosophila larval neuromuscular junction and is imperative for normal synapse function. By contrast, alternative splicing at the other alternative exon pair tunes multiple aspects of presynaptic function. While expression of one exon yields normal transmission, expression of the other reduces channel number in the AZ and thus release probability. This also abolishes presynaptic homeostatic plasticity. Moreover, reduced channel number affects short-term plasticity, which is rescued by increasing the external calcium concentration to match release probability to control. In sum, in Drosophila alternative splicing provides a mechanism to regulate different aspects of presynaptic functions with only one Ca v 2 gene.

Aging‐induced cognitive impairment is associated with a loss of metabolic homeostasis and plasticity. An emerging idea is that targeting key metabolites is sufficient to impact the function of other organisms. Therefore, more metabolism‐targeted therapeutic intervention is needed to improve cognitive impairment. We first conducted untargeted metabolomic analyses and 16S rRNA to identify the aging‐associated metabolic adaption and intestinal microbiome change. Untargeted metabolomic analyses of plasma revealed L‐arginine metabolic homeostasis was altered during the aging process. Impaired L‐arginine metabolic homeostasis was associated with low abundance of intestinal Akkermansia muciniphila ( AKK ) colonization in mice. Long‐term supplementation of AKK outer membranes protein‐Amuc_1100, rescued the L‐arginine level and restored cognitive impairment in aging mice. Mechanically, Amuc_1100 acted directly as a source of L‐arginine and enriched the L‐arginine‐producing bacteria. In aged brain, Amuc_1100 promoted the superoxide dismutase to alleviated oxidation stress, and increased nitric oxide, derivatives of L‐arginine, to improve synaptic plasticity. Meanwhile, L‐arginine repaired lipopolysaccharide‐induced intestinal barrier damage and promoted growth of colon organoid. Our findings indicated that aging‐related cognitive impairment was closely associated with the disorders of L‐arginine metabolism. AKK ‐derived Amuc_1100, as a potential postbiotic, targeting the L‐arginine metabolism, might provide a promising therapeutic strategy to maintain the intestinal homeostasis and cognitive function in aging.

INTRODUCTION New therapies to prevent or delay the onset of symptoms, slow progression, or improve cognitive and behavioral symptoms of Alzheimer's disease (AD) are needed. METHODS We interrogated clinicaltrials.gov including all clinical trials assessing pharmaceutical therapies for AD active in on January 1, 2024. We used the Common Alzheimer's Disease Research Ontology (CADRO) to classify the targets of therapies in the pipeline. RESULTS There are 164 trials assessing 127 drugs across the 2024 AD pipeline. There were 48 trials in Phase 3 testing 32 drugs, 90 trials in Phase 2 assessing 81 drugs, and 26 trials in Phase 1 testing 25 agents. Of the 164 trials, 34% (N = 56) assess disease‐modifying biological agents, 41% (N = 68) test disease‐modifying small molecule drugs, 10% (N = 17) evaluate cognitive enhancing agents, and 14% (N = 23) test drugs for the treatment of neuropsychiatric symptoms. DISCUSSION Compared to the 2023 pipeline, there are fewer trials (164 vs. 187), fewer drugs (127 vs. 141), fewer new chemical entities (88 vs. 101), and a similar number of repurposed agents (39 vs. 40). Highlights In the 2024 Alzheimer's disease drug development pipeline, there are 164 clinical trials assessing 127 drugs. The 2024 Alzheimer's disease drug development pipeline has contracted compared to the 2023 Alzheimer pipeline with fewer trials, fewer drugs, and fewer new chemical entities. Drugs in the Alzheimer's disease drug development pipeline target a wide array of targets; the most common processes targeted include neurotransmitter receptors, inflammation, amyloid, and synaptic plasticity. The total development time for a potential Alzheimer's disease therapy to progress from nonclinical studies to FDA review is approximately 13 years.

Introduction Drugs that prevent the onset, slow progression, or improve cognitive and behavioral symptoms of Alzheimer's disease (AD) are needed. Methods We searched ClinicalTrials.gov for all current Phase 1, 2 and 3 clinical trials for AD and mild cognitive impairment (MCI) attributed to AD. We created an automated computational database platform to search, archive, organize, and analyze the derived data. The Common Alzheimer's Disease Research Ontology (CADRO) was used to identify treatment targets and drug mechanisms. Results On the index date of January 1, 2023, there were 187 trials assessing 141 unique treatments for AD. Phase 3 included 36 agents in 55 trials; 87 agents were in 99 Phase 2 trials; and Phase 1 had 31 agents in 33 trials. Disease‐modifying therapies were the most common drugs comprising 79% of drugs in trials. Twenty‐eight percent of candidate therapies are repurposed agents. Populating all current Phase 1, 2, and 3 trials will require 57,465 participants. Discussion The AD drug development pipeline is advancing agents directed at a variety of target processes. HIGHLIGHTS There are currently 187 trials assessing 141 drugs for the treatment of Alzheimer's disease (AD). Drugs in the AD pipeline address a variety of pathological processes. More than 57,000 participants will be required to populate all currently registered trials.

Extensive research provides evidence that neuroinflammation underlies numerous brain disorders. However, the molecular mechanisms by which inflammatory mediators determine synaptic and cognitive dysfunction occurring in neurodegenerative diseases (e.g., Alzheimer’s disease) are far from being fully understood. Here we investigated the role of interleukin 1β (IL-1β), and the molecular cascade downstream the activation of its receptor, to the synaptic dysfunction occurring in the mouse model of multiple Herpes simplex virus type-1 (HSV-1) reactivations within the brain. These mice are characterized by neuroinflammation and memory deficits associated with a progressive accumulation of neurodegenerative hallmarks (e.g., amyloid-β protein and tau hyperphosphorylation). Here we show that mice undergone two HSV-1 reactivations in the brain exhibited increased levels of IL-1β along with significant alterations of: (1) cognitive performances; (2) hippocampal long-term potentiation; (3) expression synaptic-related genes and pre- and post-synaptic proteins; (4) dendritic spine density and morphology. These effects correlated with activation of the epigenetic repressor MeCP2 that, in association with HDAC4, affected the expression of synaptic plasticity-related genes. Specifically, in response to HSV-1 infection, HDAC4 accumulated in the nucleus and promoted MeCP2 SUMOylation that is a post-translational modification critically affecting the repressive activity of MeCP2. The blockade of IL-1 receptors by the specific antagonist Anakinra prevented the MeCP2 increase and the consequent downregulation of gene expression along with rescuing structural and functional indices of neurodegeneration. Collectively, our findings provide novel mechanistic evidence on the role played by HSV-1-activated IL-1β signaling pathways in synaptic deficits leading to cognitive impairment.

The ε4 allele of the Apolipoprotein E ( APOE ) gene is an important genetic risk factor for several neurodegenerative diseases, while the common pathogenic mechanism is still unclear. Impaired synaptic transmission is one of the common pathogenic features of neurodegenerative diseases. By using proteomics analysis, co-immunoprecipitation (Co-IP), and bimolecular fluorescence complementation (BiFC) assay, we demonstrated that APOE interacts with VAMP2, a core component of the soluble N -ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex, in an APOE4 > APOE3 manner. Further in vitro and in vivo results suggest that APOE4 blocks SNARE complex assembly, which is likely driven by liquid-liquid phase separation (LLPS), negatively regulating synaptic vesicle release. Our study shows that APOE4 negatively regulates synaptic vesicle release by blocking the soluble SNARE complex assembly. Our data shed a light on how APOE polymorphism contributes to the risk for neurodegenerative diseases, and provides a theoretical basis for the future APOE targeted treatment of neurological diseases.

The preBötzinger complex (preBötC) and the Bötzinger complex (BötC) are interconnected neural circuits that are involved in the regulation of breathing in mammals. Fast inhibitory neurotransmission is known to play an important role in the interaction of these two regions. Moreover, the corelease of glycine and GABA has been described in the respiratory network, but the contribution of the individual neurotransmitter in different pathways remains elusive. In sagittal brainstem slices of neonatal mice, we employed a laser point illumination system to activate glycinergic neurons expressing channelrhodopsin-2 (ChR2). This approach allowed us to discern the contribution of glycine and GABA to postsynaptic currents of individual whole-cell clamped neurons in the preBötC and BötC through the application of glycine and GABA receptor-specific antagonists. In more than 90% of the recordings, both transmitters contributed to the evoked IPSCs, with the glycinergic component being larger than the GABAergic component. The GABAergic component appeared to be most prominent when stimulation and recording were both performed within the preBötC. Taken together, our data suggest that GABA–glycine cotransmission is the default mode in the respiratory network of neonatal mice with regional differences that may be important in tuning the network activity.

Background The mechanism of synaptic loss in Alzheimer’s disease is poorly understood and may be associated with tau pathology. In this combined positron emission tomography (PET) and magnetoencephalography (MEG) study, we aimed to investigate spatial associations between regional tau pathology ([ 18 F]flortaucipir PET), synaptic density (synaptic vesicle 2A [ 11 C]UCB-J PET) and synaptic function (MEG) in Alzheimer’s disease. Methods Seven amyloid-positive Alzheimer’s disease subjects from the Amsterdam Dementia Cohort underwent dynamic 130-min [ 18 F]flortaucipir PET, dynamic 60-min [ 11 C]UCB-J PET with arterial sampling and 2 × 5-min resting-state MEG measurement. [ 18 F]flortaucipir- and [ 11 C]UCB-J-specific binding (binding potential, BP ND ) and MEG spectral measures (relative delta, theta and alpha power; broadband power; and peak frequency) were assessed in cortical brain regions of interest. Associations between regional [ 18 F]flortaucipir BP ND , [ 11 C]UCB-J BP ND and MEG spectral measures were assessed using Spearman correlations and generalized estimating equation models. Results Across subjects, higher regional [ 18 F]flortaucipir uptake was associated with lower [ 11 C]UCB-J uptake. Within subjects, the association between [ 11 C]UCB-J and [ 18 F]flortaucipir depended on within-subject neocortical tau load; negative associations were observed when neocortical tau load was high, gradually changing into opposite patterns with decreasing neocortical tau burden. Both higher [ 18 F]flortaucipir and lower [ 11 C]UCB-J uptake were associated with altered synaptic function, indicative of slowing of oscillatory activity, most pronounced in the occipital lobe. Conclusions These results indicate that in Alzheimer’s disease, tau pathology is closely associated with reduced synaptic density and synaptic dysfunction.

Astrocytes are recognized as more important cells than historically thought in synaptic function through the reciprocal exchange of signaling with the neuronal synaptic elements. The idea that astrocytes are active elements in synaptic physiology is conceptualized in the Tripartite Synapse concept. This review article presents and discusses recent representative examples that highlight the heterogeneity of signaling in tripartite synapse function and its consequences on neural network function and animal behavior.

Rett Syndrome is a neurodevelopmental disorder that arises from mutations in the X-linked gene methyl-CpG binding protein 2 (MeCP2). MeCP2 has a large number of targets and a wide range of functions, suggesting the hypothesis that functional signaling mechanisms upstream of synaptic and circuit maturation may contribute to our understanding of the disorder and provide insight into potential treatment. Here, we show that insulin-like growth factor-1 (IGF1) levels are reduced in young male Mecp2 -null (Mecp2 ⁻/ʸ) mice, and systemic treatment with recombinant human IGF1 (rhIGF1) improves lifespan, locomotor activity, heart rate, respiration patterns, and social and anxiety behavior. Furthermore, Mecp2 -null mice treated with rhIGF1 show increased synaptic and activated signaling pathway proteins, enhanced cortical excitatory synaptic transmission, and restored dendritic spine densities. IGF1 levels are also reduced in older, fully symptomatic heterozygous (Mecp2 ⁻/⁺) female mice, and short-term treatment with rhIGF1 in these animals improves respiratory patterns, reduces anxiety levels, and increases exploratory behavior. In addition, rhIGF1 treatment normalizes abnormally prolonged plasticity in visual cortex circuits of adult Mecp2 ⁻/⁺ female mice. Our results provide characterization of the phenotypic development of Rett Syndrome in a mouse model at the molecular, circuit, and organismal levels and demonstrate a mechanism-based therapeutic role for rhIGF1 in treating Rett Syndrome.