Function and regulation of CREB family transcription factors in the nervous system

BK channels and alcohol tolerance: Insights from studies on Drosophila, nematodes, rodents and cell lines: A systematic review

Addictive disorders markedly affect the emotional, physical and financial wellbeing of individuals, placing a substantial burden on the healthcare system. With their widespread presence in the brain, large-conductance calcium and voltage-activated potassium (BK) channels play a crucial role in various aspects of neuronal function. They contribute to behavioral tolerance and are closely linked to neuronal activity and modulation through intracellular calcium levels. As such, BK channels serve as key models for investigating the mechanisms of the effects of alcohol. Investigating their role in alcohol tolerance provides a broader understanding of their physiological and pharmacological importance. The present systematic review examined the literature on the role of BK channels in alcohol tolerance and comprehensively explored the topic. For this purpose, two databases, Web of Science and PubMed, were searched, and studies published from 2000 until June, 2024 were included. After applying specific inclusion and exclusion criteria, 35 studies underwent analysis to present a chronological overview of BK channels and their relevance in alcohol tolerance development. The studies were categorized into four main groups, according to research conducted on: i) Fruit flies; ii) nematodes; iii) rodents; and iv) cell lines. Understanding the mechanisms through which alcohol interacts with these channels may help to elucidate the cellular and molecular mechanisms underlying alcohol tolerance. There is a growing interest in developing drugs that can precisely modulate BK channel activity to treat alcohol dependence and tolerance. However, additional studies are required to fully explain the complex mechanisms through which BK channels influence alcohol-related behaviors and to interpret these findings into clinical applications.

The important role of myeloid-derived suppressor cells: From hepatitis to liver cancer

Liver homeostasis is coordinated by crosstalk between resident and infiltrating inflammatory cells. Liver disease creates a dynamic inflammatory microenvironment characterized by aberrant metabolism and continuous hepatic regeneration, making it an important risk factor for hepatocellular carcinoma (HCC) as well as liver failure. Recent studies have revealed a critical heterogeneous population of myeloid-derived suppressor cells (MDSCs), which influence liver disease progression and malignancy by dynamically regulating the immune microenvironment. MDSCs play an important role in preventing excessive immune responses in the liver. However, MDSCs are also associated with the promotion of liver injury and liver cancer progression. The plasticity of MDSCs in liver disease is a unique challenge for therapeutic intervention strategies and requires a deeper understanding of the underlying mechanisms. Here, we review the role of MDSCs in the establishment and progression of liver disease and highlight the evidence for MDSCs as a priority target for current and future therapeutic strategies. We explore the fate of MDSCs from hepatitis to liver cancer, providing recent insights into potential targets for clinical intervention.

Sleep is enhanced in aged male mice that overexpress calcium/calmodulin-dependent protein kinase IV

The dysregulation of sleep-wake patterns that occurs during aging is well documented and coincides with changes in intracellular signaling pathways that regulate sleep, such as the calcium/calmodulin-dependent protein kinase (CaMKII)/cyclic-AMP response element-binding protein (CREB) pathway. However, much less is known about the relationship between other CREB-activating members of the CaMK family, such as calcium/calmodulin-dependent protein kinase IV (CaMKIV), and the regulation of sleep. Using 2- to 4-month-old (young adult) and 22- to 24-month-old (aged) male and female CaMKIV-overexpressing (CaMKIV-OE) mice, we observed that overexpression of CaMKIV in the forebrain decreased wakefulness and increased the amount of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep in aged male mice, but not young adult male mice, in comparison to age- and sex-matched controls. Conversely, female mice overexpressing CaMKIV displayed no significant differences in the percentage of time spent in each vigilance state compared to their wild-type counterparts, regardless of age. While CaMKIV overexpression also led to more sleep-wake fragmentation in young adult and aged male mice, aged female mice displayed more consolidated NREM sleep. Overall, our results suggest that CaMKIV overexpression enhances sleep in aged male mice, and differentially affects sleep-wake architecture based on sex and age, providing insights into the potential mechanism by which CaMKIV overexpression enhances memory.

Alpha-Synuclein drives NURR1 and NLRP3 Inflammasome dysregulation in Parkinson's disease: From pathogenesis to potential therapeutic strategies

Parkinson's disease (PD), a progressive neurodegenerative disorder, is characterized by the loss of dopaminergic neurons and pathological aggregation of α-synuclein (α-Syn). Emerging evidence highlights the interplay between genetic susceptibility, neuroinflammation, and transcriptional dysregulation in driving PD pathogenesis. This review brings together the latest information on three important players: α-Syn, the transcription factor Orphan nuclear receptor (NURR1), and the NOD-like receptor 3 (NLRP3) inflammasome. Pathogenic α-syn aggregates cause damage to neurons by disrupting mitochondria and lysosomes and spreading in a way similar to prion proteins. They also turn on the NLRP3 inflammasome, which is a key player in neuroinflammation. NLRP3-driven release of pro-inflammatory cytokines exacerbates neurodegeneration and creates a self-sustaining inflammatory milieu. Meanwhile, reduced NURR1 activity, a pivotal modulator of dopaminergic neuron survival and development, exposes neurons to oxidative stress, neuroinflammation, and α-Syn toxicity, hence exacerbating disease progression. So, targeting this trio exhibits transformative potential against PD pathogenesis.

Complement 3 (C3) within the hypothalamic arcuate nucleus is a potential key mediator of the effect of enhanced nutrition on reproductive development in young bull calves

BACKGROUND

Reproductive development may be advanced in bull calves through enhanced dietary intake during the early life period. This effect between enhanced nutrition with subsequent earlier reproductive development is orchestrated through signalling within the hypothalamic-pituitary-testicular axis. Within the hypothalamus, the arcuate nucleus (ARC) is crucial for the integration of peripheral metabolic status with subsequent gonadotropin releasing hormone (GnRH) signalling; however, the precise molecular control regulating this effect is not fully known. The aim of this study was to evaluate the global transcriptomic and proteomic responses to varied plane of nutrition during early calf-hood in young dairy bull calves. Additionally, we sought to integrate these 'omics' datasets to determine key genes and proteins contributing to earlier reproductive development. Between 2-12 weeks of age, 30 Holstein-Friesian bull calves (mean age: 17.5 days; mean bodyweight 48.8 kg), were offered either a high or moderate plane of nutrition with 15 calves in each group. At 12 weeks of age, all calves were euthanised and the ARC tissue isolated from each calf. The ARC tissue was then used for global transcriptomic (miRNAseq and mRNAseq) and proteomic analyses.

RESULTS

Bioinformatic analyses were undertaken to determine differentially expressed transcripts (FDR < 0.1; fold change > 1.5) between the dietary treatment groups, resulting in the identification of 1 differentially expressed miRNA (miR-2419-3p) and 83 differentially expressed mRNA in the ARC region. mRNA target gene prediction identified Complement 3 (C3) as a target of miR-2419-3p, suggesting a relationship between the two transcripts. Furthermore, through a co-regulatory network analysis conducted on the proteomics dataset, C3 was revealed as a hub protein. Additionally, through the proteomic network analysis, C3 was interacting with proteins involved in both insulin and GnRH signalling, highlighting a potential role for C3 in mediated the effect of enhanced nutritional status with earlier reproductive development within the ARC.

CONCLUSION

This study highlights an effect of altered plane of nutrition in early life on the molecular control of the hypothalamic ARC. Additionally, results generated suggest a potential role for the C3 gene in mediating the interaction between enhanced metabolic status with reproductive development within the ARC, regulated by miR-2419-3p.

Role of sacubitril/valsartan in modulating diabetes mediated cognitive and neuronal impairment

Earlier investigations had established that Diabetes mellitus (DM) caused significant damage in the central nervous system, bringing about diabetic encephalopathy and increasing the risk of cognitive-related problems. Nonetheless, the inherent pathophysiology of cognitive dysfunctions in DM is not well understood. The current study aimed to examine the possible influences of sacubitril/valsartan (SAC/VAL), an angiotensin receptor blocker/neprilysin inhibitor (ARNI), on cognitive dysfunction associated with streptozotocin (STZ)-induced diabetic rats. SAC/VAL and VAL treatments were initiated three days after the diabetic condition was established and continued daily for eight weeks. Normal, non-diabetic rats were reserved as a control group. Both SAC/VAL and VAL treatment in diabetic rats ameliorated diabetes induced oxidative stress as indicated by reduced malondialdehyde (MDA), increased total antioxidant capacity (TAO) in hippocampal tissue and decreased serum advanced glycation end products (AGEs), also inflammatory and apoptotic changes were observed and proved by the reduction of tumor necrosis factor alpha (TNF-α) and caspase -3 in rat hippocampus. SAC/VAL administration to diabetic rats also improved neuronal damages as reflected by restored cAMP response element-binding protein (CREB), brain derived neurotrophic factor (BDNF) and pre-synaptic phosphoproteins, synapsin I and growth associated protein-43 (GAP-43) in the hippocampus of diabetic rats. Additionally, SAC/VAL treated diabetic rats markedly reduced signs of cognitive deterioration during the Morris water maze test. Collectively, these findings suggested that SAC/VAL might play a vital role in improvement of the cognitive impairment observed in diabetic rats through antioxidant, anti-inflammatory and anti-apoptotic actions.

Transcription and epigenetic factor dynamics in neuronal activity-dependent gene regulation

Neuronal activity, including sensory-evoked and spontaneous firing, regulates the expression of a subset of genes known as activity-dependent genes. A key issue in this process is the activation and accumulation of transcription factors (TFs), which bind to cis-elements at specific enhancers and promoters, ultimately driving RNA synthesis through transcription machinery. Epigenetic factors such as histone modifiers also play a crucial role in facilitating the specific binding of TFs. Recent evidence from epigenome analyses and imaging studies have revealed intriguing mechanisms: the default chromatin structure at activity-dependent genes is formed independently of neuronal activity, while neuronal activity modulates spatiotemporal dynamics of TFs and their interactions with epigenetic factors (EFs). In this article we review new insights into activity-dependent gene regulation that affects brain development and plasticity.

Significance of NMDA receptor-targeting compounds in neuropsychological disorders: An in-depth review

N-methyl-D-aspartate receptors (NMDARs), a subclass of glutamate-gated ion channels, play an integral role in the maintenance of synaptic plasticity and excitation-inhibition balance within the central nervous system (CNS). Any irregularities in NMDAR functions, whether hypo-activation or over-activation, can destabilize neural networks and impair CNS function. Several decades of experimental and clinical investigations have demonstrated that NMDAR dysfunction is implicated in the pathophysiology of various neurological disorders. Despite designing a long list of compounds that differentially modulate NMDARs, success in developing drugs that can selectively and effectively regulate various NMDAR subtypes while showing encouraging efficacy in clinical settings remains limited. A better understanding of the basic mechanism of NMDAR function, particularly its selective regulation in pathological conditions, could aid in designing effective drugs for the treatment of neurological conditions. Here, we reviewed the experimental and clinical investigations that studied the effects of available NMDAR modulators in various neurological disorders and weighed up the pros and cons of the use of these substances on the improvement of functional outcomes of these disorders. Despite numerous efforts to develop NMDAR modulatory drugs that did not produce the desired outcomes, NMDARs remain a significant target for advancing novel drugs to treat neurological disorders. This article reviews the complexity of NMDAR signaling dysfunction in different neurological diseases, the efforts taken to examine designed compounds targeting specific subtypes of NMDARs, including challenges associated with using these substances, and the potential enhancements in drug discovery for NMDAR modulatory compounds by innovative technologies.

DA.Vra1-congenic rats display increased gene expression and Schwann cell apoptosis but unaffected nerve regeneration compared to parental DA rats after sciatic nerve injury and repair

Introduction

The rat Vra1 locus, containing glutathione S-transferase alpha 4 (Gsta4), regulates the degeneration of central nervous system (CNS) neurons in toxin-, protein-, and injury-based models. We hypothesize that Piebald Virol Glaxo.1AV1 (PVG) alleles in Vra1 confer protection and increased axonal outgrowth after peripheral nerve injury and repair.

Methods

DA rats (n = 14) and DA rats with PVG alleles in the Vra1 locus (DA.Vra1, n = 14) were subjected to sciatic nerve transection and immediate repair. After 6 days, axonal outgrowth and protein and gene expression were analyzed in injured and uninjured nerves and dorsal root ganglia (DRG).

Results

No differences in axonal outgrowth were observed between strains, but the number of apoptotic Schwann cells in the injured distal nerve end was higher in DA.Vra1 than in DA rats (p = 0.003). In both strains, gene- and protein expression of activating transcription factor 3 (ATF3) and 27-kDa heat shock protein (HSP27, i.e., Hspb1) were increased in injured vs. uninjured DRG. In DA.Vra1 rats, Gsta4 gene expression was lower in injured vs. uninjured DRG (p = 0.043) but higher than in DA rats in injured nerves (p = 0.008) and injured DRG (p = 0.008). DA.Vra1 had higher gene expression of Atf3 (p = 0.016) and caspase 3 (p = 0.032) in injured nerves than DA rats.

Discussion

Results highlight the complexity of nerve injury and repair, supporting further investigation of Gsta4 in nerve regeneration.

Sigma-1 receptor agonist PRE-084 increases BDNF by activating the ERK/CREB pathway to rescue learning and memory impairment caused by type II diabetes

Sigma-1 receptor (Sig-1R) agonists has therapeutic effects in neurological disorders and possesses properties that can reverse cognitive dysfunction. This study investigated the therapeutic efficacy of Sig-1R activation on cognitive dysfunction in streptozotocin (STZ) combined with high fat and high sugar diet (HFD)-induced type 2 diabetic rats. By employing morris water maze (MWM) testing and computed tomography (CT) imaging, we observed that activation of Sig-1R effectively mitigated brain atrophy and cognitive impairment in diabetes-induced cognitive impairment (DCI) rats. Given the fundamental role of intact hippocampal synaptic plasticity in maintaining cognitive function, we investigated the correlation between Sig-1R and Brain-Derived Neurotrophic Factor (BDNF), a well-established neurotrophic factor. And we also analyzed the expression of Postsynaptic density protein-95 (PSD95) protein. Golgi staining, Haematoxylin-eosin (HE) staining, Nissl staining, and immunofluorescence results show that activating Sig-1R can upregulate BDNF expression and reducing synaptic damage in hippocampal neurons. To elucidate the mechanism by which Sig-1R activation leads to increased BDNF levels, we investigated the Extracellular Signal-Regulated Kinase/Cyclic AMP Response Element-Binding Protein(ERK/CREB) protein pathway. In vitro and in vivo, we observed that Sig-1R activates the ERK/CREB signaling pathway, thereby stimulating BDNF release and increased PSD95 expression. Further intervention with BD1047 antagonist and Tropomyosin-Related Kinase B (TrkB) antagonist ANA-12 confirmed our conclusion that Sig-1R activation upregulated p-ERK and p-CREB protein expression, promoted BDNF transcription, the expression of PSD95 protein was up-regulated, reduces synaptic damage in damaged hippocampal neurons, and rescued cognitive impairment in DCI rats.

Volatile oil of Acori tatarinowii rhizoma: potential candidate drugs for mitigating dementia

Objective

This study aims to elucidate the mitigating effects of the volatile oil of Acori tatarinowii rhizoma (ATR) on dementia, in order to provide a reference for future research and applications of the volatile oil of ATR in the field of dementia.

Materials and methods

A search strategy was developed using terms such as "Acori tatarinowii rhizoma," "Acorus tatarinowii Schott," "Asarone," and "Dementia." The literature search was conducted in PubMed, Web of Science, and Google Scholar, and studies not meeting the inclusion criteria were excluded. This study summarizes the main metabolites, active ingredients, toxicological properties, and pharmacokinetic characteristics of the volatile oil from ATR in mitigating dementia, with a particular focus on its potential mechanisms of action. Furthermore, the study highlights the limitations of existing research and offers insights into future research directions.

Results

The volatile oil of ATR mitigates dementia through multiple pathways, including reducing abnormal protein aggregation, promoting neurogenesis, inhibiting neuronal apoptosis, regulating neurotransmitters, improving synaptic function, modulating autophagy, countering cellular stress, reducing neuroinflammation, and alleviating vascular risk factors.

Conclusion

The multi-pathway pharmacological effects of the volatile oil of ATR are well-aligned with the complex mechanisms of dementia progression, highlighting its significant therapeutic potential for anti-dementia applications. This provides new perspectives for the development of more effective anti-dementia drugs. Nonetheless, further rigorous and high-quality preclinical and clinical investigations are required to address key issues, including the chemical characterization of the volatile oil of ATR, potential synergistic effects among active ingredients, toxicity profiles, and definitive clinical efficacy.

Pterostilbene Potentiates the NGF-TrkA Signaling Pathway, Enhancing Differentiation in PC12 Cells

Pterostilbene, a stilbenoid found in vegetables and natural products, has therapeutic potential due to its multiple pharmacological actions. In the brain, the nerve growth factor (NGF) is a pivotal neurotrophic factor, serving for neuronal survival and differentiation. The decline in NGF levels in aged individuals contributes to the development of neurodegenerative processes and cognitive impairment. Here, we aim to explore the effect of pterostilbene on promoting neuron-like differentiation in PC12 cells, a well-established model to study neuronal differentiation, by potentiating the functions of NGF. Molecular docking and ultrafiltration assays were performed to examine the direct binding of pterostilbene with NGF. The mechanisms underlying the stimulation of PC12 cell differentiation, characterized by enhanced neurite outgrowth and increased neurofilament expression, were determined through TrkA/Akt/CREB signaling pathways. The combined treatment of pterostilbene with a low dose of NGF significantly potentiated the NGF-induced neurite extension and neurofilament expression. Pterostilbene enhanced the effect of NGF on promoting neuron-like differentiation, which was related to increased activation of the TrkA signaling pathway. This upstream event was associated with increased phosphorylation of Akt and CREB. The selective inhibitors of TrkA (K252a) and PI3K/Akt (LY294002) were applied to validate the NGF/TrkA/Akt signaling pathways leading to diminished neurite outgrowth and reduced expression of neurofilaments in cells treated with pterostilbene and NGF. Taken together, the results indicate that pterostilbene could potentiate NGF/TrkA activity, enhancing neuron-like differentiation in PC12 cells under a low concentration of NGF. These findings suggest that the application of pterostilbene could be a promising alternative therapeutic strategy to improve NGF efficacy.

Insulin acts on astrocytes to shift their substrate preference to fatty acids

It is increasingly recognized that brain can β-oxidize fatty acids for use as an energy substrate. However, mechanism(s) by which neural cells switch their preference from glucose to fatty acids are not fully elucidated. Here we provide evidence that insulin acts directly on astrocytes to promote the uptake of glucose and fatty acids while modifying their substrate preference through a sequential shift in the expression of genes associated with fatty acid uptake, synthesis, transport, and metabolism. Under these conditions, fatty acids are converted into TCA cycle intermediates to satisfy astrocyte energy demands, allowing pyruvate derived from glucose to be directed toward the production of lactate; a preferred fuel for neurons. This shift in astrocyte energy substrate preference is required for insulin to enhance long-term potentiation in the Schaffer collateral. These findings establish a homeostatic mechanism where insulin promotes LTP by switching the energy substrate preference of astrocytes to fatty acids.

CaMK2A/CREB pathway activation is associated with enhanced mitophagy and neuronal apoptosis in diabetic retinopathy

Diabetic retinopathy (DR) is a common complication of diabetes mellitus, characterized by progressive neurodegeneration and vision impairment. The Ca2+/calmodulin-dependent protein kinase II alpha (CaMK2A) and cAMP response element-binding protein (CREB) signaling pathway has been implicated in various neurological disorders. However, its role in DR pathogenesis remains elusive. We established a DR mouse model by streptozotocin administration and performed histological, biochemical, and molecular analyses to investigate the involvement of CaMK2A/CREB signaling and its interplay with mitophagy. Additionally, we employed in vitro high-glucose (HG) treatment in primary mouse retinal ganglion cells to dissect the underlying mechanisms. Pharmacological and genetic modulations were utilized to target CaMK2A/CREB pathway and mitophagy. In the DR model, we observed retinal degeneration, increased apoptosis, and reduced neurotransmitter production, accompanied by enhanced mitophagy and activation of the CaMK2A/CREB pathway. HG induction in retinal ganglion cells recapitulated these findings, and autophagy inhibition partially rescued cell death but failed to suppress CaMK2A/CREB activation, suggesting mitophagy as a downstream consequence. CaMK2A knockdown or CREB phosphorylation inhibition attenuated HG-induced mitophagy, apoptosis, and neurotransmitter depletion, while CREB activation exacerbated these effects. CaMK2A silencing mitigated DR progression, oxidative stress, inflammation, and neuronal loss, akin to dopamine/carbidopa administration in DR mouse model. Our findings reveal the involvement of CaMK2A/CREB signaling activation and enhanced mitophagy in DR, suggesting these pathways may be therapeutically relevant targets for DR management.

Disruption of Ephb1 causes reduced hypothalamic CRH and TRH expression and obesity in mice

OBJECTIVE

Ephrin type-B receptor 1 (EphB1) is a receptor tyrosine kinase involved in axon guidance, synaptic plasticity, and tumorigenesis. However, the role of EphB1 in metabolic regulation and obesity remains poorly understood. This study aims to uncover the role of EphB1 in energy metabolism and provide insights into the underlying mechanisms by which EphB1 regulates obesity.

METHODS

Two Ephb1 mutations identified from a forward genetic screen for obesity-related loci in mice were examined for their effects in gene expression, energy metabolism, and endocrine changes. The impacts of EphB1 on neuropeptide expression and signal transduction were evaluated in both hypothalamic tissues and primary cells. Potential downstream signals were modified in Ephb1 mutants to verify the interaction.

RESULTS

Ephb1 mutants develop obesity in adolescence and develop impaired glucose tolerance during adulthood. EphB1 deficiency caused lower body temperature, blunted cold-induced thermogenesis, and decreased locomotor activity, but it did not alter food intake. EphB1 promotes cyclic AMP-responsive element-binding protein (CREB) phosphorylation via phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling in a cell-autonomous manner. EphB1 deficiency leads to reduced expression of corticotropin-releasing hormone (CRH) and thyrotropin-releasing hormone (TRH) in the brain. Intraventricular administration of either TRH or a CRH fragment suppressed obesity in Ephb1 mutants.

CONCLUSIONS

EphB1 regulates hypothalamic CRH and TRH expression and promotes energy expenditure in mice.

cAMP response element-binding protein: A credible cancer drug target

Despite advancements in radiotherapy, chemotherapy, endocrine therapy, targeted therapy, and immunotherapy, resistance to therapy remains a pervasive challenge in oncology, in part owing to tumor heterogeneity. Identifying new therapeutic targets is key to addressing this challenge because it can both diversify and enhance existing treatment options, particularly through combination regimens. The cAMP response element-binding protein (CREB) is a transcription factor involved in various biological processes. It is aberrantly activated in several aggressive cancer types, including breast cancer. Clinically, high CREB expression is associated with increased breast tumor aggressiveness and poor prognosis. Functionally, CREB promotes breast cancer cell proliferation, survival, invasion, metastasis, as well as therapy resistance by deregulating genes related to apoptosis, cell cycle, and metabolism. Targeting CREB with small molecule inhibitors has demonstrated promise in preclinical studies. This review summarizes the current understanding of CREB mechanisms and their potential as a therapeutic target. SIGNIFICANCE STATEMENT: cAMP response element-binding protein (CREB) is a master regulator of multiple biological processes, including neurodevelopment, metabolic regulation, and immune response. CREB is a putative proto-oncogene in breast cancer that regulates the cell cycle, apoptosis, and cellular migration. Preclinical development of CREB-targeting small molecules is underway.

Oroxylin A Attenuates Homocysteine-Induced Blood-Brain Barrier (BBB) Dysfunction by Reducing Endothelial Permeability and Activating the CREB/Claudin-5 Signaling Pathway

Recent reports have indicated that elevated levels of homocysteine (Hcy) are closely linked to blood-brain barrier (BBB) dysfunction in neurological disorders. Oroxylin A (OA) is a key bioactive flavonoid that has been reported to regulate brain functions. However, the role of OA in Hcy-related BBB dysfunction is less reported. In this study, we aimed to elucidate the role and molecular mechanism of OA in Hcy-mediated BBB dysfunction using both in vivo and in vitro investigations. Our findings indicate that the expression of the tight junction (TJ) protein Claudin-5 declined, and the diffusion of sodium fluorescein elevated in brains of Hcy-challenged mice. These effects were notably rescued by administration of OA. In Hcy-challenged bEnd.3 brain microvascular endothelial cells, increased endothelial permeability, reduced trans-endothelial electrical resistance (TEER), and downregulated Claudin-5 were observed. These effects were significantly reversed by 25 and 50 μM OA. Interestingly, OA treatment restored the dephosphorylation of CREB at Ser133 induced by Hcy. However, the addition of the protein kinase A/cAMP-response element binding protein (PKA/CREB) inhibitor H89 counteracted the protective effects of OA on inhibiting endothelial permeability and promoting Claudin-5 expression. Together, we demonstrate that OA protects against Hcy-induced BBB dysfunction by maintaining the integrity of endothelial barriers. This protective effect is achieved through the activation of the CREB/Claudin-5 signaling pathway, highlighting the potential therapeutic value of OA in addressing BBB-related neurological disorders.

Memantine and amantadine KLVFF peptide conjugates: Synthesis, structure determination, amyloid-β interaction and effects on recognition memory in mice

BACKGROUND

Adamantane derivatives, such as memantine (Mem) and amantadine (Ada), have distinct mechanisms and therapeutic applications. Ada is primarily utilized as an antiviral and anti-Parkinson drug without significant pro-cognitive effects, Mem is effective in various clinical conditions characterized by cognitive deficits, including Alzheimer's disease. Recent evidence highlights a neuroprotective role for Aβ monomers, suggesting that preventing their aggregation into toxic oligomers could be a promising therapeutic strategy. Based on the observation that the Lys-Leu-Val-Phe-Phe (KLVFF) peptide, can block the transition of randomly coiled Aβ monomers into toxic β-sheet aggregates, two KLVFF conjugates, the Mem-Succ-KLVFF and Ada-Succ-KLVFF were investigated.

METHODS

Peptides were synthesized by Microwave-Assisted Solid Phase Peptide Synthesis (MW-SPPS). Circular Dichroism (CD), Th-T fluorescence and Gel-Electrophoresis techniques were used to assess the inhibitory effect on Aβ42 fibrillogenesis. The formation of inclusion complexes with β-Cyclodextrin (β-CyD) was demonstrated by NMR Spectroscopy. The Novel Object Recognition (NOR) test, followed by double-blind analysis, was applied for in vivo response to compounds administration. In vitro effects on neurons were studied by MTT assay and WB analysis, whereas HR ESI-MS allowed the molecular detection on brain homogenates.

RESULTS

These compounds differently affect Aβ42 aggregation. Mem-Succ-KLVFF, and Succ-KLVFF affect pCREB levels in differentiated SH-SY5Y, a signaling pathway involved in memory processes. In the NOR test, both Mem and KLVFF exhibited pro-cognitive effects individually and synergistically when co-administered.

CONCLUSION

Structure-activity relationships are discussed, integrating in vivo results, memory-related cellular pathways, and HR-ESI-MS analyses. These findings support the therapeutic potential of these compounds in preserving cognitive function.

Inter-organelle communication dynamically orchestrates juvenile hormone biosynthesis and female reproduction

Inter-organelle communication coordinates cellular homeostasis and function. Juvenile hormone (JH) is produced in the corpora allata (CA) and acts as a gonadotrophic hormone in most insects. Using transcriptomic, biochemical, molecular, and genetic analyses, here we investigated the underlying mechanism of how inter-organelle communication dynamically orchestrates JH biosynthesis and female reproduction in the American cockroach, Periplaneta americana. The extracellular stimuli insulin and allatostatin act through their membrane receptors and antagonistically regulate RyR-mediated Ca2+ release from the endoplasmic reticulum in CA cells. Ca2+-activated CaMKII stimulates energy metabolism in the mitochondria partially via SLC25A6, and induces the expression of JH biosynthetic genes HMGR, Jhamt, and Cyp15a1 through activating transcription factor CREB, which recruits CBP for histone acetylation in the nucleus. Additionally, mitochondria interact with CREB-CBP through mitonuclear communication to regulate JH biosynthesis. From the perspective of inter-organelle communication, this comprehensive study significantly advanced our understanding of hormone biosynthesis and reproductive biology in insects.

The Primary Cilia are Associated with the Axon Initial Segment in Neurons

The primary cilia serve as pivotal mediators of environmental signals and play crucial roles in neuronal responses. Disruption of ciliary function has been implicated in neuronal circuit disorders and aberrant neuronal excitability. However, the precise mechanisms remain elusive. To study the link between the primary cilia and neuronal excitability, manipulation of somatostatin receptor 3 (SSTR3) is investigated, as an example of how alterations in ciliary signaling may affect neuronal activity. It is found that aberrant SSTR3 expression perturbed not only ciliary morphology but also disrupted ciliary signaling cascades. Genetic deletion of SSTR3 resulted in perturbed spatial memory and synaptic plasticity. The axon initial segment (AIS) is a specialized region in the axon where action potentials are initiated. Interestingly, loss of ciliary SSTR3 led to decrease of Akt-dependent cyclic AMP-response element binding protein (CREB)-mediated transcription at the AIS, specifically downregulating AIS master organizer adaptor protein ankyrin G (AnkG) expression. In addition, alterations of other ciliary proteins serotonin 6 receptor (5-HT6R)and intraflagellar transport protein 88 (IFT88) also induced length changes of the AIS. The findings elucidate a specific interaction between the primary cilia and AIS, providing insight into the impact of the primary cilia on neuronal excitability and circuit integrity.

Topological identification and interpretation for single-cell epigenetic regulation elucidation in multi-tasks using scAGDE

Single-cell ATAC-seq technology advances our understanding of single-cell heterogeneity in gene regulation by enabling exploration of epigenetic landscapes and regulatory elements. However, low sequencing depth per cell leads to data sparsity and high dimensionality, limiting the characterization of gene regulatory elements. Here, we develop scAGDE, a single-cell chromatin accessibility model-based deep graph representation learning method that simultaneously learns representation and clustering through explicit modeling of data generation. Our evaluations demonstrated that scAGDE outperforms existing methods in cell segregation, key marker identification, and visualization across diverse datasets while mitigating dropout events and unveiling hidden chromatin-accessible regions. We find that scAGDE preferentially identifies enhancer-like regions and elucidates complex regulatory landscapes, pinpointing putative enhancers regulating the constitutive expression of CTLA4 and the transcriptional dynamics of CD8A in immune cells. When applied to human brain tissue, scAGDE successfully annotated cis-regulatory element-specified cell types and revealed functional diversity and regulatory mechanisms of glutamatergic neurons.

Neuroprotection by 4R-cembranoid against Gulf War Illness-related Chemicals is mediated by ERK, PI3K, and CaMKII pathways

Gulf War Illness (GWI) has been consistently linked to exposure to pyridostigmine (PB), N,N-Diethyl-meta-toluamide (DEET), permethrin (PER), and traces of sarin. In this study, diisopropylfluorophosphate (DFP, sarin surrogate) and the GWI-related chemicals were found to reduce the number of functionally active neurons in rat hippocampal slices. These findings confirm a link between GWI neurotoxicants and N-Methyl-D-Aspartate (NMDA)-mediated excitotoxicity, which was successfully reversed by Edelfosine (a phospholipase Cβ (PLCβ3) inhibitor) and Flupirtine (a Kv7 channel agonist). To test whether 4R-cembranoid (4R), a nicotinic α7 acetylcholinesterase receptor (α7AChR) modulator known for its neuroprotective properties, can restore hippocampal neurons from glutamate-induced neurotoxicity, we exposed rat hippocampal slices with DFP for 10 min followed by 60 min treatment with 4R. We investigated the 4R mechanisms of neuroprotection after preincubation with LY294002, PD98059, and KN-62. The inhibition of the phosphatidylinositol 3-kinase (PI3K), mitogen-activated protein kinase (MEK1/2), and calcium/calmodulin-dependent protein kinase (CaMKII) abrogated the protective effect of 4R against DFP-induced neurotoxicity. In separate experiments, after incubation with DFP, followed by 4R for 1 h, cellular extracts were prepared for Western blotting of phospho-Akt, phospho-GSK3β, phosphorylated extracellular signal-regulated kinase (ERK)1/2, CaMKII and cAMP response element-binding protein (CREB). Our results show that DFP induces neuronal dysfunction by dephosphorylation, while 4R restores the phosphorylation of Akt, GSK3, ERK1/2, CREB, and CaMKII. Moreover, our proteomics analysis supported the notion that 4R activates additional signaling pathways related to enhancing neuronal signaling, synaptic plasticity, and apoptotic inhibition to promote cell survival against DFP, offering biomarkers for developing treatment against GWI.

Danggui-Shaoyao-San Can Ameliorate Alzheimer's Disease by Inhibiting Hippocampal Neuron Apoptosis: Findings from Serum Pharmacology

Background

Danggui-Shaoyao-San (DSS) is a traditional Chinese medicine prescription with a history of nearly 2000 years, originally widely used for gynecological diseases, and in recent years research has found that DSS also has a good therapeutic effect on Alzheimer's disease (AD).

Purpose

The objective is to investigate the metabolic components of the DSS in the blood and the potential mechanisms for AD.

Materials and Methods

Liquid chromatography‒mass spectrometry (LC-MS) combined with gas chromatography‒mass spectrometry (GC-MS) based non-targeted metabolomics were used to conduct in-depth research. Serum Pharmacology was used to analyze potential mechanisms of DSS for AD. C57BL/6J mice and Hippocampal neuronal cell line (HT-22) were used to prepare the AD model. Enzyme linked immunosorbent assay (Elisa), quantitative polymerase chain reaction (q-PCR), Morris water maze,Western blot (WB), Immunohistochemical and Immunofluorescence were used to study the effect of DSS on AD. Flow cytometry and Cell Counting Kit-8 (CCK-8) reveal the effect of DSS serum on HT-22 proliferation and apoptosis.

Results

A total of 57 metabolic components were screened in DSS serum. Serum Pharmacology revealed that the calcium signaling pathway and cAMP/PKA/CREB pathway may be a potential mechanism through which DSS treated AD. DSS can reduce aberrant phosphorylation of Tau and modulates cAMP/PKA/CREB pathway to improve cognition and apoptosis in AD mice. DSS serum can increase the cell viability of HT-22 and reduce apoptosis mainly by alleviating mitochondrial calcium overloading.

Conclusion

DSS can modulate the calcium signaling pathway and enhance the cAMP/PKA/CREB signaling pathway to ameliorate Tau aberrant phosphorylation, cognitive deficits and neuronal apoptosis after AD.

Impact of Polyphenol-Rich Nutraceuticals on Cognitive Function and Neuroprotective Biomarkers: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

BACKGROUND

Recent studies have highlighted the neuroprotective effects of polyphenols, particularly their role in enhancing brain-derived neurotrophic factor (BDNF) and cAMP response element-binding protein (CREB) activity. This study aimed to evaluate the relationship between BDNF and CREB levels and cognitive performance in individuals undergoing a polyphenol-rich dietary intervention.

METHODS

A randomized, crossover, double-blind, placebo-controlled clinical trial was conducted with 92 participants. The intervention involved the daily intake of an encapsulated concentrate of fruit, vegetable, and berry juice powders (Juice Plus+ Premium®) over two 16-week periods, separated by a 4-week washout phase. Cognitive function was assessed using the Stroop Test, Trail Making Test, and Reynolds Intellectual Screening Test (RIST). The plasma levels of CREB and BDNF were measured using ELISA.

RESULTS

The polyphenol-rich product significantly improved cognitive performance, as evidenced by higher scores in the Stroop Test and RIST, compared to the placebo. Additionally, the plasma levels of CREB and BDNF were notably elevated in the product condition, indicating enhanced neuroprotective activity.

CONCLUSIONS

The findings suggest that polyphenol-rich nutraceuticals can modulate neurobiological mechanisms underlying cognitive improvements, primarily through the reduction of oxidative stress and the regulation of signaling pathways associated with synaptic plasticity. These results support the potential of dietary polyphenols in promoting cognitive health and preventing neurodegenerative diseases.

PI3K-mediated Kif1a DNA methylation contributes to neuropathic pain: an in vivo study

ABSTRACT

Neuropathic pain (NP) is a chronic condition caused by nerve injuries, such as nerve compression. Understanding its underlying neurobiological mechanisms is critical for developing effective treatments. Previous studies have shown that Kinesin family member 1A (Kif1a) heterozygous deficient mice display sensory deficits in response to nociceptive stimuli. PI3K has been found to mitigate these sensory deficits by enhancing Kif1a transcription, highlighting KIF1A's key role in sensory pain. However, the exact mechanism through which PI3K regulates KIF1A expression in relation to pain remains unclear. In this study, we observed a significant increase in PI3K/AKT/CREB (cyclic AMP response element-binding protein) protein levels in the dorsal root ganglia and spinal cord after chronic constriction injury in both male and female C57BL/6 mice. Notably, elevated levels of TET1, as well as Kif1a mRNA and protein, were detected in both male and female mice. Activated (phosphorylated-CREB) p-CREB recruited the DNA demethylase TET1, which interacted with the Kif1a promoter, reducing methylation and increasing Kif1a mRNA and protein expression. PI3K inhibition using wortmannin reversed the demethylation of Kif1a and decreased its expression in male mice. Furthermore, TET1 knockdown or overexpression significantly affected pain-related behaviors, as well as Kif1a methylation and transcription. Female mice given intrathecal injections of PI3K inhibitors exhibited similar molecular and behavioral outcomes as male mice. These findings offer new insights into NP mechanisms, suggesting that targeting the PI3K/KIF1A axis could be a promising therapeutic approach for NP treatment.

A Neuroprotective Peptide Modulates Retinal cAMP Response Element-Binding Protein (CREB), Synapsin I (SYN1), and Growth-Associated Protein 43 (GAP43) in Rats with Silicone Oil-Induced Ocular Hypertension

This study evaluated the neuroprotective potential of peptain-1 conjugated to a cell-penetrating peptide (CPP-P1) in an ocular hypertension model of glaucoma. Brown Norway (BN) rats were subjected to intraocular pressure (IOP) elevation via intracameral injection of silicone oil (SO), with concurrent intravitreal injections of either CPP-P1 or a vehicle. Retinal cross-sections were analyzed for markers of neuroprotection, including cAMP response element-binding protein (CREB), phosphorylated CREB (p-CREB), growth-associated protein-43 (GAP43), synapsin-1 (SYN1), and superoxide dismutase 2 (SOD2). Hematoxylin and eosin staining was used to assess retinal-layer thickness. SO-treated rats exhibited significant reductions in the thickness of the inner nuclear layer (INL, 41%, p = 0.016), inner plexiform layer (IPL, 52%, p = 0.0002), and ganglion cell layer (GCL, 57%, p = 0.001). CPP-P1 treatment mitigated these reductions, preserving INL thickness by 32% (p = 0.059), IPL by 19% (p = 0.119), and GCL by 31% (p = 0.057). Increased levels of CREB (p = 0.17) and p-CREB (p = 0.04) were observed in IOP-elevated, CPP-P1-treated retinas compared to IOP-elevated, vehicle-treated retinas. Although overall GAP43 levels were low, there was a modest increase in expression within the IPL and GCL in SO- and CPP-P1-treated retinas (p = 0.15 and p = 0.09, respectively) compared to SO- and vehicle-treated retinas. SO injection reduced SYN1 expression in both IPL and GCL (p = 0.01), whereas CPP-P1 treatment significantly increased SYN1 levels in the IPL (p = 0.03) and GCL (p = 0.002). While SOD2 expression in the GCL was minimal across all groups, a trend toward increased expression was observed in CPP-P1-treated animals (p = 0.16). The SO model was replicated with SO removal after 7 days and monitored for 21 days followed by retinal flat-mount preparation to assess retinal ganglion cell (RGC) survival. A 42% loss in RGCs (p = 0.009) was observed in SO-injected eyes, which were reduced by approximately 37% (p = 0.03) with CPP-P1 treatment. These findings suggest that CPP-P1 is a promising neuroprotective agent that promotes retinal ganglion cell survival and the preservation of other retinal neurons, potentially through enhanced CREB signaling in a rat model of SO-induced ocular hypertension.

CREB-Binding Protein Regulates Cocaine- and Amphetamine-Regulated Transcript Peptide Expression in the Lateral Hypothalamus: Implication in Reward and Reinforcement

Neuropeptide cocaine- and amphetamine-regulated transcript peptide (CARTp) is known to play an important role in reward processing. The rats conditioned to intra-cranial self-stimulation (ICSS) showed massive upregulation of CART protein and mRNA in the vicinity of the electrode implanted to deliver the electric current directly at the lateral hypothalamus (LH)-medial forebrain bundle (MFB) area. However, the underlying mechanisms leading to the upregulation of CART in ICSS animals remain elusive. We tested the putative role of CREB-binding protein (CBP), an epigenetic enzyme with intrinsic histone acetyltransferase (HAT) activity, in regulating CART expression during ICSS. An electrode was implanted in LH-MFB and the rats were conditioned to self-stimulation in an operant chamber. CBP siRNA was delivered ipsilaterally in the LH-MFB to knock-down CBP and the effects on lever press activity were monitored. While ICSS-conditioned rats showed distinct increase in CART, CBP and pCREB levels, enhanced CBP binding and histone acetylation (H3K9ac) were noticed on the CART promoter in chromatin immunoprecipitation assay. Direct infusion of CBP siRNA in the LH-MFB lowered lever press activity, CBP levels, histone acetylation at the CART promoter, and CART mRNA and peptide expression. Co-infusion of CARTp in LH-MFB rescued the waning effects of CBP siRNA on self-stimulation. We suggest that CBP-mediated histone acetylation may play a causal role in CART expression in LH, which in turn may drive the positive reinforcement of lever press activity.

Investigating the Therapeutic Mechanisms of Total Saikosaponins in Alzheimer's Disease: A Metabolomic and Proteomic Approach

Alzheimer's disease (AD) is the leading cause of dementia among the elderly, yet effective treatments remain elusive. Total saikosaponins (TSS), the primary bioactive components in Bupleurum chinense, have shown promising therapeutic effects against AD in previous studies. Methods: To delve deeper into the mechanisms underlying the therapeutic role of TSS in AD, we investigated its neuroprotective effects and associated molecular mechanisms in APP/PS1 mice. Further, we employed metabolomic and proteomic analyses, with a focus on the potential protein-level changes induced by TSS, particularly those related to metabolite accumulation in the brain. Results: Our results showed that lysophosphatidylcholine, adenosine, and sphingomyelin in plasma might serve as potential biomarkers. Compared to the control group, AD mice exhibited significantly increased expression of proteins related to neuroinflammatory pathways, whereas proteins involved in cAMP signaling, cGMP-PKG signaling, and synaptic plasticity pathways were significantly downregulated. Notably, these signaling pathways were partially reversed in APP/PS1 mice following TSS administration. Behavioral tests demonstrated that TSS effectively improved the learning and memory functions of mice. Conclusions: Our findings suggest that TSS ameliorate cognitive decline through regulating neuroinflammatory pathways, cAMP and cGMP signaling, and synaptic plasticity pathways, providing insights into its therapeutic potential in AD.

Integrative multiomics reveals common endotypes across PSEN1, PSEN2, and APP mutations in familial Alzheimer's disease

BACKGROUND

PSEN1, PSEN2, and APP mutations cause Alzheimer's disease (AD) with an early age at onset (AAO) and progressive cognitive decline. PSEN1 mutations are more common and generally have an earlier AAO; however, certain PSEN1 mutations cause a later AAO, similar to those observed in PSEN2 and APP.

METHODS

We examined whether common disease endotypes exist across these mutations with a later AAO (~ 55 years) using hiPSC-derived neurons from familial Alzheimer's disease (FAD) patients harboring mutations in PSEN1A79V, PSEN2N141I, and APPV717I and mechanistically characterized by integrating RNA-seq and ATAC-seq.

RESULTS

We identified common disease endotypes, such as dedifferentiation, dysregulation of synaptic signaling, repression of mitochondrial function and metabolism, and inflammation. We ascertained the master transcriptional regulators associated with these endotypes, including REST, ASCL1, and ZIC family members (activation), and NRF1 (repression).

CONCLUSIONS

FAD mutations share common regulatory changes within endotypes with varying severity, resulting in reversion to a less-differentiated state. The regulatory mechanisms described offer potential targets for therapeutic interventions.

Melanin-like nanoparticles slow cyst growth in ADPKD by dual inhibition of oxidative stress and CREB

Melanin-like nanoparticles (MNPs) have recently emerged as valuable agents in antioxidant therapy due to their excellent biocompatibility and potent capacity to scavenge various reactive oxygen species (ROS). However, previous studies have mainly focused on acute ROS-related diseases, leaving a knowledge gap regarding their potential in chronic conditions. Furthermore, apart from their well-established antioxidant effects, it remains unclear whether MNPs target other intracellular molecular pathways. In this study, we synthesized ultra-small polyethylene glycol-incorporated Mn2+-chelated MNP (MMPP). We found that MMPP traversed the glomerular filtration barrier and specifically accumulated in renal tubules. Autosomal dominant polycystic kidney disease (ADPKD) is a chronic genetic disorder closely associated with increased oxidative stress and featured by the progressive enlargement of cysts originating from various segments of the renal tubules. Treatment with MMPP markedly attenuated oxidative stress levels, inhibited cyst growth, thereby improving renal function. Interestingly, we found that MMPP effectively inhibits a cyst-promoting gene program downstream of the cAMP-CREB pathway, a crucial signaling pathway implicated in ADPKD progression. Mechanistically, we observed that MMPP directly binds to the bZIP DNA-binding domain of CREB, leading to competitive inhibition of CREB's DNA binding ability and subsequent reduction in CREB target gene expression. In summary, our findings identify an intracellular target of MMPP and demonstrate its potential for treating ADPKD by simultaneously targeting oxidative stress and CREB transcriptional activity.

Liquid-liquid phase separation in hepatocellular carcinoma

Liquid-liquid phase separation (LLPS) drives the formation of membraneless intracellular compartments within both cytoplasm and nucleus. These compartments can form distinct physicochemical environments, and in particular display different concentrations of proteins, RNA, and macromolecules compared to the surrounding cytosol. Recent studies have highlighted the significant role of aberrant LLPS in cancer development and progression, impacting many core processes such as oncogenic signalling pathways, transcriptional dysregulation, and genome instability. In hepatocellular carcinoma (HCC), aberrant formation of biomolecular condensates has been observed in a number of preclinical models, highlighting their significance as an emerging factor in understanding cancer biology and its molecular underpinnings. In this review, we summarize emerging evidence and recent advances in understanding the role of LLPS in HCC, with a particular focus on the regulation and dysregulation of cytoplasmic and nuclear condensates in cancer cells. We finally discuss how an emerging understanding of phase separation processes in HCC opens up new potential treatment avenues.

Neuroprotective Effects of STAT3 Inhibitor on Hydrogen Peroxide-Induced Neuronal Cell Death via the ERK/CREB Signaling Pathway

This study investigates the neuroprotective potential of STAT3 inhibition in reducing oxidative stress-induced neuronal damage and apoptosis, a major factor contributing to the onset and progression of neurodegenerative diseases, including Alzheimer's disease (AD). Our findings demonstrate that STAT3 inhibitors significantly enhance cell survival and reduce apoptosis in SH-SY5Y cells exposed to hydrogen peroxide. These protective effects are mediated through the ERK/CREB signaling pathway rather than direct suppression of STAT3 phosphorylation. Further analysis revealed that the ERK pathway is a critical mediator of CREB activation following STAT3 inhibition. The protective effects of STAT3 inhibitors were significantly reduced in the presence of the ERK inhibitor PD98059, underscoring the importance of the ERK/CREB axis in neuroprotection. We observed that STAT3 inhibitors promote CREB phosphorylation, leading to the upregulation of immediate early genes such as c-Fos, c-Jun, Arc, Egr-1, NR4A1, and Homer1a, as well as BDNF. These genes are crucial for synaptic plasticity and long-term memory formation, suggesting that STAT3 inhibition may ameliorate cognitive impairments in neurodegenerative conditions. Our results highlight the potential of STAT3 inhibitors to counteract oxidative stress and enhance cognitive functions by modulating the ERK/CREB signaling pathway. These findings provide valuable insights into the molecular mechanisms of STAT3 inhibition and support its therapeutic potential for treating neurodegenerative diseases.

Rhoifolin, baicalein 5,6-dimethyl ether and agathisflavone prevent amnesia induced in scopolamine zebrafish (Danio rerio) model by increasing the mRNA expression of bdnf, npy, egr-1, nfr2α, and creb1 genes

The increasing attention towards age-related diseases has generated significant interest in the concept of cognitive dysfunction associated with Alzheimer's disease (AD). Certain limitations are associated with the current therapies, and flavonoids have been reported to exhibit multiple biological activities and anti-AD effects in several AD models owing to their antioxidative, anti-inflammatory, and anti-amyloidogenic properties. In this study, we performed an initial in silico predictions of the pharmacokinetic properties of three flavonoids (rhoifolin, baicalein 5,6-dimethyl ether and agathisflavone). Subsequently, we evaluated the antiamnesic and antioxidant potential of flavonoids in concentrations of 1, 3, and 5 μg/L in scopolamine (100 μM)-induced amnesic zebrafish (Danio rerio) model. Zebrafish behavior was analyzed by novel tank diving test (NTT), Y-maze, and novel object recognition test (NOR). Acetylcholinesterase (AChE) activity, brain antioxidant status and the expression of bdnf, npy, egr1, nrf2α, creb1 genes, and CREB-1 protein level was measured to elucidate the underlying mechanism of action. Our flavonoids improved memory and decreased anxiety-like behavior of scopolamine-induced amnesia in zebrafish. Also, the studied flavonoids reduced AChE activity and brain oxidative stress and upregulated the gene expression, collectively contributing to neuroprotective properties. The results of our study add new perspectives on the properties of flavonoids to regulate the evolution of neurodegenerative diseases, especially AD, by modulating the expression of genes involved in the regulation of synaptic plasticity, axonal growth, and guidance, sympathetic and vagal transmission, the antioxidant response and cell proliferation and growth.

Early disruption of the CREB pathway drives dendritic morphological alterations in FTD/ALS cortical neurons

Synaptic loss and dendritic degeneration are common pathologies in several neurodegenerative diseases characterized by progressive cognitive and/or motor decline, such as Alzheimer's disease (AD) and frontotemporal dementia/amyotrophic lateral sclerosis (FTD/ALS). An essential regulator of neuronal health, the cAMP-dependent transcription factor CREB positively regulates synaptic growth, learning, and memory. Phosphorylation of CREB by protein kinase A (PKA) and other cellular kinases promotes neuronal survival and maturation via transcriptional activation of a wide range of downstream target genes. CREB pathway dysfunction has been strongly implicated in AD pathogenesis, and recent data suggest that impaired CREB activation may contribute to disease phenotypes in FTD/ALS as well. However, the mechanisms behind reduced CREB activity in FTD/ALS pathology are not clear. In this study, we found that cortical-like neurons derived from iPSC lines carrying the hexanucleotide repeat expansion in the C9ORF72 gene, a common genetic cause of FTD/ALS, displayed a diminished activation of CREB, resulting in decreased dendritic and synaptic health. Importantly, we determined such impairments to be mechanistically linked to an imbalance in the ratio of regulatory and catalytic subunits of the CREB activator PKA and to be conserved in C9-ALS patient's postmortem tissue. Modulation of cAMP upstream of this impairment allowed for a rescue of CREB activity and an amelioration of dendritic morphology and synaptic protein levels. Our data elucidate the mechanism behind early CREB pathway dysfunction and discern a feasible therapeutic target for the treatment of FTD/ALS and possibly other neurodegenerative diseases.

Euonymus hamiltonianus Extract Improves Amnesia in APPswe/Tau Transgenic and Scopolamine-Induced Dementia Models

Dementia is a syndrome exhibiting progressive impairments on cognition and behavior beyond the normal course of aging, and Alzheimer's disease (AD) is one of the neurodegenerative diseases known to cause dementia. We investigated the effect of KGC07EH, the 30% ethanol extract of Euonymus hamiltonianus, against amyloid-β (Aβ) production and cognitive dysfunction in dementia models. KGC07EH was treated on Hela cells expressing the Swedish mutant form of amyloid precursor protein (APP), and the AD triple transgenic (3× TG) mice were given KGC07EH orally during 11-14 months of age (100 and 300 mg/kg/day). SH-SY5Y cell line was used to test KGC07EH on scopolamine-induced elevation of acetylcholinesterase (AChE) activity. ICR mice were intraperitoneally injected with scopolamine, and KGC07EH was administered orally (50, 100, and 200 mg/kg/day) for 4 weeks. KGC07EH treatment decreased Aβ, sAPPβ-sw, and sAPPβ-wt levels and APP protein expressions while sAPPα was increased in Swedish mutant-transfected HeLa cells. KGC07EH treatment also significantly reduced the accumulation of Aβ plaques and tau tangles in the brain of 3× TG mice as well as improving the cognitive function. In SH-SY5Y cells cultured with scopolamine, KGC07EH dose-dependently attenuated the increase of AChE activity. KGC07EH also improved scopolamine-induced learning and memory impairment in scopolamine-injected mice, and in their cerebral cortex and hippocampus, the expression levels of p-ERK, p-CREB, p-Akt, and BDNF were attenuated. KGC07EH inhibits APP processing and Aβ production both in vitro and in vivo, while enhancing acetylcholine signaling and cognitive dysfunction which are the major symptoms of dementia.

Protective Effect of Protocatechuic Acid on Oxidative Damage and Cognitive Impairment in Pb-Induced Rats

Protocatechuic acid (PCA), a class of water-soluble phenolic acid abundant in the human diet, has been shown to be of great nutritional interest and to have medicinal value. However, the protective effects against lead (Pb)-induced body injury have not been elucidated. In this study, we explored the protective effect of PCA on Pb-induced oxidative damage and cognitive impairment in rats. The results showed that PCA could reduce the Pb content in rat bodies (blood, bone, brain, liver, and kidney) after Pb exposure. Moreover, PCA may inhibit Pb-induced oxidative damage by increasing the activity of antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decreasing the level of malondialdehyde (MDA) in the brain, liver, and kidney. In addition, PCA may alleviate Pb-induced learning and memory impairment by upregulating neurotransmitter levels; maintaining the normal function of N-methyl-D-aspartate receptors (NMDARs); and promoting Ca2+ influx, thus activating signaling molecules, related protein kinases, and transcription factors in the cAMP-PKA-CREB pathway. In general, PCA could reduce oxidative stress and ameliorate the learning and memory deficits in Pb-treated rats, indicating that PCA may be an effective preventive agent and treatment or plumbism.

Oxytocin Protects Against Corticosterone-Induced DA Dysfunction: An Involvement of the PKA/CREB Pathway

Chronic stress disrupts dopamine (DA) transmission, adversely affecting mood and contribution to neuropsychiatric disorders like ADHD, autism, schizophrenia, anxiety, depression, and drug addiction. The neuropeptide oxytocin (OXT) plays a key role in social cognition, bonding, attachment, and parenting behaviors. In addition, OXT can modulate the activity of the HPA axis, counteracting the effects of stress, and alleviating fear and anxiety. However, whether OXT can mitigate stress-induced DA dysfunction and the underlying mechanisms remains unclear. This study investigated the neuroprotective effects of OXT on corticosterone (CORT) induced DA dysfunction in the neuroblastoma cell line SH-SY5Y. The results revealed that CORT decreases the levels of intracellular signaling molecules associated with DA function, including phosphorylated tyrosine hydroxylase (pTH), phosphorylated cAMP response element-binding protein (pCREB), and protein kinase A (PKA). Interestingly, pretreatment with OXT mitigated CORT-induced DA dysfunction through its potent PKA activator properties. In addition, the neuroprotective effect of OXT was abolished by atosiban (an OXT receptor antagonist) or H89 (a PKA inhibitor). Our results suggest that OXT protects dopaminergic neuroblastoma cells from CORT-induced DA dysfunction, potentially through the involvement of oxytocin receptors and the PKA/CREB signaling pathway. These findings contribute to the understanding of the neurobiological mechanisms underlying stress resilience and highlight potential pathways for developing targeted treatments that leverage the neuroprotective properties of OXT to address disorders characterized by DA dysregulation and impaired stress responses.

The cell adhesion molecule CD44 acts as a modulator of 5-HT7 receptor functions

BACKGROUND

Homo- and heteromerization of G protein-coupled receptors (GPCRs) plays an important role in the regulation of receptor functions. Recently, we demonstrated an interaction between the serotonin receptor 7 (5-HT7R), a class A GPCR, and the cell adhesion molecule CD44. However, the functional consequences of this interaction on 5-HT7R-mediated signaling remained enigmatic.

METHODS

Using a quantitative FRET (Förster resonance energy transfer) approach, we determined the affinities for the formation of homo- and heteromeric complexes of 5-HT7R and CD44. The impact of heteromerization on 5-HT7R-mediated cAMP signaling was assessed using a cAMP responsive luciferase assay and a FRET-based cAMP biosensor under basal conditions as well as upon pharmacological modulation of the 5-HT7R and/or CD44 with specific ligands. We also investigated receptor-mediated G protein activation using BRET (bioluminescence resonance energy transfer)-based biosensors in both, homo- and heteromeric conditions. Finally, we analyzed expression profiles for 5-HT7R and CD44 in the brain during development.

RESULTS

We found that homo- and heteromerization of the 5-HT7R and CD44 occur at similar extent. Functionally, heteromerization increased 5-HT7R-mediated cAMP production under basal conditions. In contrast, agonist-mediated cAMP production was decreased in the presence of CD44. Mechanistically, this might be explained by increased Gαs and decreased GαoB activation by 5-HT7R/CD44 heteromers. Unexpectedly, treatment of the heteromeric complex with the CD44 ligand hyaluronic acid boosted constitutive 5-HT7R-mediated cAMP signaling and receptor-mediated transcription, suggesting the existence of a transactivation mechanism.

CONCLUSIONS

Interaction with the hyaluronan receptor CD44 modulates both the constitutive activity of 5-HT7R as well as its agonist-mediated signaling. Heteromerization also results in the transactivation of 5-HT7R-mediated signaling via CD44 ligand.

Diversity of Microglia-Derived Molecules with Neurotrophic Properties That Support Neurons in the Central Nervous System and Other Tissues

Microglia, the brain immune cells, support neurons by producing several established neurotrophic molecules including glial cell line-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF). Modern analytical techniques have identified numerous phenotypic states of microglia, each associated with the secretion of a diverse set of substances, which likely include not only canonical neurotrophic factors but also other less-studied molecules that can interact with neurons and provide trophic support. In this review, we consider the following eight such candidate cytokines: oncostatin M (OSM), leukemia inhibitory factor (LIF), activin A, colony-stimulating factor (CSF)-1, interleukin (IL)-34, growth/differentiation factor (GDF)-15, fibroblast growth factor (FGF)-2, and insulin-like growth factor (IGF)-2. The available literature provides sufficient evidence demonstrating murine cells produce these cytokines and that they exhibit neurotrophic activity in at least one neuronal model. Several distinct types of neurotrophic activity are identified that only partially overlap among the cytokines considered, reflecting either their distinct intrinsic properties or lack of comprehensive studies covering the full spectrum of neurotrophic effects. The scarcity of human-specific studies is another significant knowledge gap revealed by this review. Further studies on these potential microglia-derived neurotrophic factors are warranted since they may be used as targeted treatments for diverse neurological disorders.

Experience-dependent, sexually dimorphic synaptic connectivity defined by sex-specific cadherin expression

Early-life experience influences subsequent maturation and function of the adult brain, sometimes even in a sex-specific manner, but underlying molecular mechanisms are poorly understood. We describe here how juvenile experience defines sexually dimorphic synaptic connectivity in the adult Caenorhabditis elegans nervous system. Starvation of juvenile males disrupts serotonin-dependent activation of the CREB transcription factor in a nociceptive sensory neuron, PHB. CREB acts through a cascade of transcription factors to control expression of an atypical cadherin protein, FMI-1/Flamingo/CELSR. During postembryonic development, FMI-1 promotes and maintains synaptic connectivity of PHB to a command interneuron, AVA, in both sexes, but a serotonin-dependent transcriptional regulatory cassette antagonizes FMI-1 expression in males, thereby establishing sexually dimorphic connectivity between PHB and AVA. A critical regulatory node is the CREB-target LIN-29, a Zn finger transcription factor that integrates four layers of information: sexual specificity, past experience, time and cell-type specificity. Our findings provide the mechanistic details of how an early juvenile experience defines sexually dimorphic synaptic connectivity.

Potential neuroprotective effects of 2-hydroxypropyl-β cyclodextrin against amyloid β (1-42)-induced neurotoxicity on the rat hippocampus

The neurodegenerative mechanisms of Alzheimer's disease (AD) are not fully understood, but it is believed that amyloid beta (Aβ) peptide causes oxidative stress, neuroinflammation, and disrupts metabotropic glutamate receptor 5 (mGluR5) signaling by interacting with cholesterol and caveolin-1 (Cav-1) in pathogenic lipid rafts. This study examined the effect of 2-hydroxypropyl-β-cyclodextrin (HP-CD) on cholesterol, oxidative stress (total oxidant status), neuroinflammation (TNF-α), and mGluR5 signaling molecules such as PKCβ1, PKCβ2, ERK1/2, CREB, BDNF, and NGF in Aβ (1-42)-induced neurotoxicity. The Sprague-Dawley rats were divided into four groups: control (saline), Aβ (1-42), HP-CD (100 mg/kg), and Aβ (1-42) + HP-CD (100 mg/kg). All groups received bilateral stereotaxic injections of Aβ (1-42) or saline into the hippocampus. After surgery, HP-CD was administered intraperitoneally (ip) for 7 days. Cholesterol, TNF-α, and TOS levels were measured in synaptosomes isolated from hippocampus tissue using spectrophotometry, fluorometry, and enzyme immunoassay, respectively. The gene expressions of Cav-1, mGluR5, PKCβ1, PKCβ2, ERK1/2, CREB, BDNF, and NGF in hippocampus tissue were evaluated using reverse transcription PCR after real-time PCR analysis. Treatment with Aβ (1-42) significantly elevated cholesterol, TOS, TNF-α, Cav-1, PKCβ2, and ERK1/2 levels. Additionally, mGluR5, CREB, and BDNF levels were shown to be lowered. HP-CD reduced cholesterol, TOS, and TNF-α levels while increasing mGluR5, CREB, and BDNF in response to Aβ (1-42) treatment. These findings indicate that HP-CD may have neuroprotective activity due to the decreased levels of cholesterol, oxidative stress, and neuroinflammation, as well as upregulated levels of mGluR5, CREB, and BDNF.

Effects of exercise on brain-derived neurotrophic factor in Alzheimer's disease models: A systematic review and meta-analysis

A growing body of research examining effects of exercise on brain-derived neurotrophic factor (BDNF) in Alzheimer's disease (AD) models, while due to differences in gender, age, disease severity, brain regions examined, and type of exercise intervention, findings of available studies were conflicting. In this study, we aimed to evaluate current evidence regarding effects of exercise on BDNF in AD models. Searches were performed in PubMed, Web of Science, Cochrane, and EBSCO electronic databases, through July 20, 2023. We included studies that satisfied the following criteria: eligible studies should (1) report evidence on experimental work with AD models; (2) include an exercise group and a control group (sedentary); (3) use BDNF as the outcome indicator; and (4) be randomized controlled trials (RCTs). From 1196 search records initially identified, 36 studies met the inclusion criteria. There was a significant effect of exercise on increasing BDNF levels in AD models [standardized mean differences (SMD) = 0.98, P < 0.00001]. Subgroup analysis showed that treadmill exercise (SMD = 0.92, P< 0.0001), swimming (SMD = 1.79, P< 0.0001), and voluntary wheel running (SMD = 0.51, P= 0.04) were all effective in increasing BDNF levels in AD models. In addition, exercise significantly increased BDNF levels in the hippocampus (SMD = 0.92, P< 0.00001) and cortex (SMD = 1.56, P= 0.02) of AD models. Exercise, especially treadmill exercise, swimming, and voluntary wheel running, significantly increased BDNF levels in hippocampus and cortex of AD models, with swimming being the most effective intervention type.

Effect of Short-Term Restraint Stress on the Expression of Genes Associated with the Response to Oxidative Stress in the Hypothalamus of Hypertensive ISIAH and Normotensive WAG Rats

Normotensive and hypertensive organisms respond differently to stress factors; however, the features of the central molecular genetic mechanisms underlying the reaction of the hypertensive organism to stress have not been fully established. In this study, we examined the transcriptome profiles of the hypothalamus of hypertensive ISIAH rats, modeling a stress-sensitive form of arterial hypertension, and normotensive WAG rats at rest and after exposure to a single short-term restraint stress. It was shown that oxidative phosphorylation is the most significantly enriched process among metabolic changes in the hypothalamus of rats of both strains when exposed to a single short-term restraint stress. The analysis revealed DEGs representing both a common response to oxidative stress for both rat strains and a strain-specific response to oxidative stress for hypertensive ISIAH rats. Among the genes of the common response to oxidative stress, the most significant changes in the transcription level were observed in Nos1, Ppargc1a, Abcc1, Srxn1, Cryab, Hspb1, and Fosl1, among which Abcc1 and Nos1 are associated with hypertension, and Fosl1 and Ppargc1a encode transcription factors. The response to oxidative stress specific to hypertensive rats is associated with the activation of the Fos gene. The DEG's promoter region enrichment analysis allowed us to hypothesize that the response to oxidative stress may be mediated by the participation of the transcription factor CREB1 (Cyclic AMP-responsive element-binding protein 1) and the glucocorticoid receptor (NR3C1) under restraint stress in the hypothalamus of both rat strains. The results of the study revealed common and strain-specific features in the molecular mechanisms associated with oxidative phosphorylation and oxidative stress response in the hypothalamus of hypertensive ISIAH and normotensive WAG rats following a single short-term restraint stress. The obtained results expand the understanding of the most significant molecular targets for further research aimed at developing new therapeutic strategies for the prevention of the consequences of acute emotional stress, taking into account the hypertensive state of the patient.

CREB Is Critically Implicated in Skin Mast Cell Degranulation Elicited via FcεRI and MRGPRX2

Skin mast cells (MCs) mediate acute allergic reactions in the cutaneous environment and contribute to chronic dermatoses, including urticaria, and atopic or contact dermatitis. The cAMP response element binding protein (CREB), an evolutionarily well conserved transcription factor (TF) with over 4,000 binding sites in the genome, was recently found to form a feedforward loop with KIT, maintaining MC survival. The most selective MC function is degranulation with its acute release of prestored mediators. Herein, we asked whether CREB contributes to the expression and function of the degranulation-competent receptors FcεRI and MRGPRX2. Interference with CREB by pharmacological inhibition (CREBi, 666-15) or RNA interference only slightly affected the expression of these receptors, while KIT was strongly attenuated. Interestingly, MRGPRX2 surface expression moderately increased following CREB-knockdown, whereas MRGPRX2-dependent exocytosis simultaneously decreased. FcεRI expression and function were regulated consistently, although the effect was stronger at the functional level. Preformed MC mediators (tryptase, histamine, β-hexosaminidase) remained comparable following CREB attenuation, suggesting that granule synthesis did not rely on CREB function. Collectively, in contrast to KIT, FcεRI and MRGPRX2 moderately depend on unperturbed CREB function. Nevertheless, CREB is required to maintain MC releasability irrespective of stimulus, insinuating that CREB may operate by safeguarding the degranulation machinery. To our knowledge, CREB is the first factor identified to regulate MRGPRX2 expression and function in opposite direction. Overall, the ancient TF is an indispensable component of skin MCs, orchestrating not only survival and proliferation but also their secretory competence.

Therapeutic efficacy of Genistein in activation of neuronal AC/cAMP/CREB/PKA and mitochondrial ETC-Complex pathways in experimental model of autism: Evidence from CSF, blood plasma and brain analysis

Autism is a complex neurodevelopmental condition characterized by repetitive behaviors, impaired social communication, and various associated conditions such as depression and anxiety. Its multifactorial etiology includes genetic, environmental, dietary, and gastrointestinal contributions. Pathologically, Autism is linked to mitochondrial dysfunction, oxidative stress, neuroinflammation, and neurotransmitter imbalances involving GABA, glutamate, dopamine, and oxytocin. Propionic acid (PRPA) is a short-chain fatty acid produced by gut bacteria, influencing central nervous system functions. Elevated PRPA levels can exacerbate Autism-related symptoms by disrupting metabolic processes and crossing the blood-brain barrier. Our research investigates the neuroprotective potential of Genistein (GNT), an isoflavone compound with known benefits in neuropsychiatric and neurodegenerative disorders, through modulation of the AC/cAMP/CREB/PKA signaling pathway and mitochondrial ETC complex (I-IV) function. In silico analyses revealed GNT's high affinity for these targets. Subsequent in vitro and in vivo experiments using a PRPA-induced rat model of autism demonstrated that GNT (40 and 80 mg/kg., orally) significantly improves locomotion, neuromuscular coordination, and cognitive functions in PRPA-treated rodents. Behavioral assessments showed reduced immobility in the forced swim test, enhanced Morris water maze performance, and restored regular locomotor activity. On a molecular level, GNT restored levels of key signaling molecules (AC, cAMP, CREB, PKA) and mitochondrial complexes (I-V), disrupted by PRPA exposure. Additionally, GNT reduced neuroinflammation and apoptosis, normalized neurotransmitter levels, and improved the complete blood count profile. Histopathological analyses confirmed that GNT ameliorated PRPA-induced brain injuries, restored normal brain morphology, reduced demyelination, and promoted neurogenesis. The study supports GNT's potential in autism treatment by modulating neural pathways, reducing inflammation, and restoring neurotransmitter balance.

GAN-WGCNA: Calculating gene modules to identify key intermediate regulators in cocaine addiction

Understanding time-series interplay of genes is essential for diagnosis and treatment of disease. Spatio-temporally enriched NGS data contain important underlying regulatory mechanisms of biological processes. Generative adversarial networks (GANs) have been used to augment biological data to describe hidden intermediate time-series gene expression profiles during specific biological processes. Developing a pipeline that uses augmented time-series gene expression profiles is needed to provide an unbiased systemic-level map of biological processes and test for the statistical significance of the generated dataset, leading to the discovery of hidden intermediate regulators. Two analytical methods, GAN-WGCNA (weighted gene co-expression network analysis) and rDEG (rescued differentially expressed gene), interpreted spatiotemporal information and screened intermediate genes during cocaine addiction. GAN-WGCNA enables correlation calculations between phenotype and gene expression profiles and visualizes time-series gene module interplay. We analyzed a transcriptome dataset of two weeks of cocaine self-administration in C57BL/6J mice. Utilizing GAN-WGCNA, two genes (Alcam and Celf4) were selected as missed intermediate significant genes that showed high correlation with addiction behavior. Their correlation with addictive behavior was observed to be notably significant in aspect of statistics, and their expression and co-regulation were comprehensively mapped in terms of time, brain region, and biological process.

Role of canonical and non-canonical cAMP sources in CRHR2α-dependent signaling

Hippocampal neurons exhibit activation of both the conventional transmembrane adenylyl cyclases (tmACs) and the non-canonical soluble adenylyl cyclase (sAC) as sources of cyclic AMP (cAMP). These two cAMP sources play crucial roles in mediating signaling pathways downstream of CRHR1 in neuronal and neuroendocrine contexts. In this study, we investigate the involvement of both cAMP sources in the molecular mechanisms triggered by CRHR2α. Here we provide evidence demonstrating that UCN1 and UCN3 exert a neuritogenic effect on HT22-CRHR2α cells, which is solely dependent on the cAMP pool generated by sAC and PKA activity but independent of ERK1/2 activation. Through the characterization of the effectors implicated in neurite elongation, we found that CREB phosphorylation and c-Fos induction rely on PKA activity and ERK1/2 phosphorylation, underscoring the critical role of signaling pathway regulation. These findings strengthen the concept that localized cAMP microdomains actively participate in the regulation of these signaling processes.

Decoding Arc transcription: a live-cell study of stimulation patterns and transcriptional output

Activity-regulated cytoskeleton-associated protein (Arc) plays a crucial role in synaptic plasticity, a process integral to learning and memory. Arc transcription is induced within a few minutes of stimulation, making it a useful marker for neuronal activity. However, the specific neuronal activity patterns that initiate Arc transcription have remained elusive due to the inability to observe mRNA transcription in live cells in real time. Using a genetically encoded RNA indicator (GERI) mouse model that expresses endogenous Arc mRNA tagged with multiple GFPs, we investigated Arc transcriptional activity in response to various electrical field stimulation patterns. The GERI mouse model was generated by crossing the Arc-PBS knock-in mouse, engineered with binding sites in the 3' untranslated region (UTR) of Arc mRNA, and the transgenic mouse expressing the cognate binding protein fused to GFP. In dissociated hippocampal neurons, we found that the pattern of stimulation significantly affects Arc transcription. Specifically, theta-burst stimulation consisting of high-frequency (100 Hz) bursts delivered at 10 Hz frequency induced the highest rate of Arc transcription. Concurrently, the amplitudes of nuclear calcium transients also reached their peak with 10 Hz burst stimulation, indicating a correlation between calcium concentration and transcription. However, our dual-color single-cell imaging revealed that there were no significant differences in calcium amplitudes between Arc-positive and Arc-negative neurons upon 10 Hz burst stimulation, suggesting the involvement of other factors in the induction of Arc transcription. Our live-cell RNA imaging provides a deeper insight into the complex regulation of transcription by activity patterns and calcium signaling pathways.

Hydrolyzed Chicken Meat Extract and Its Bioactive Cyclopeptides Protect Neural Function by Attenuating Inflammation and Apoptosis via PI3K/AKT and AMPK Pathways

Cognitive decline is inevitable with age, and due to the lack of well-established pharmacotherapies for neurodegenerative disorders, dietary supplements have become important alternatives to ameliorate brain deterioration. Hydrolyzed chicken meat extract (HCE) and its bioactive components were previously found to improve neuroinflammation and cognitive decline by regulating microglia polarization. However, the effects and mechanisms of these bioactives on neurons remain unclear. Here, the most potent bioactive component on neural function in HCE was screened out, and the detailed mechanism was clarified through in vivo and in vitro experiments. We found that HCE, cyclo(Val-Pro), cyclo(Phe-Phe), cyclo(His-Pro), cyclo(Leu-Lys), and arginine exerted stronger anti-inflammatory and antioxidant effects among the 12 bioactives in amyloid β (Aβ)-treated HT-22 cells. Further transcriptome sequencing and polymerase chain reaction (PCR) array analysis showed that these bioactives participated in different signaling pathways, and cyclo(Val-Pro) was identified as the most potent cyclic dipeptide. In addition, the antiapoptotic and neuroprotective effect of cyclo(Val-Pro) was partly regulated by the activation of PI3K/AKT and AMPK pathways, and the inhibition of these pathways abolished the effect of cyclo(Val-Pro). Moreover, cyclo(Val-Pro) enhanced cognitive function and neurogenesis and alleviated neuroinflammation and oxidative stress in middle-aged mice, with an effect similar to HCE. Hippocampal transcriptome analysis further revealed that HCE and cyclo(Val-Pro) significantly enriched the neuroactive ligand-receptor interaction pathway, verified by enhanced neurotransmitter levels and upregulated neurotransmitter receptor-related gene expression. Therefore, the mechanism of cyclo(Val-Pro) on neural function might be associated with PI3K/AKT and AMPK pathway-mediated antiapoptotic effect and neurogenesis and the activation of the neurotransmitter-receptor pathway.

Phosphodiesterase 7 inhibitor reduces stress-induced behavioral and cytoarchitectural changes in C57BL/6J mice by activating the BDNF/TrkB pathway

Background

Phosphodiesterase 7 (PDE7) plays a role in neurological function. Increased expression and activity of PDE7 has been detected in several central nervous system diseases. However, the role of PDE7 in regulating stress levels remains unclear. Thus, this study aimed to determine whether and how PDE7 involved in the stress-induced behavioral and neuron morphological changes.

Methods

The single prolonged stress (SPS) was used to build a stress exposure model in C57BL/6 J mice and detected PDE7 activity in hippocampus, amygdala, prefrontal cortex and striatum. Next, three doses (0.2, 1, and 5 mg/kg) of the PDE7 inhibitor BRL-50481 were intraperitoneally administered for 10 days, then behavioral, biochemical, and morphological tests were conducted.

Results

PDE7 activity in hippocampus of mice significantly increased at all times after SPS. BRL-50481 significantly attenuated SPS induced anxiety-like behavior and fear response in both context and cue. In addition, BRL-50481 increased the levels of key molecules in the cAMP signaling pathway which were impaired by SPS. Immunofluorescent staining and Sholl analysis demonstrated that BRL-50481 also restored the nucleus/cytoplasm ratio of hippocampal neurons and improved neuronal plasticity. These effects of BRL-50481 were partially blocked by the TrkB inhibitor ANA-12.

Conclusion

PDE7 inhibitors attenuate stress-induced behavioral changes by protecting the neuron cytoarchitecture and the neuronal plasticity in hippocampus, which is mediated at least partly through the activation of BDNF/TrkB signaling pathway. These results proved that PDE7 is a potential target for treating stress-induced behavioral and physiological abnormalities.