Involvement of PI3K/Akt/FoxO3a and PKA/CREB Signaling Pathways in the Protective Effect of Fluoxetine Against Corticosterone-Induced Cytotoxicity in PC12 Cells

Glutamate transporter activator LDN-212320 prevents chronic pain-induced cognitive impairment and anxiety-like behaviors in a mouse model

The astroglial glutamate transporter in the hippocampus and anterior cingulate cortex (ACC) is critically involved in chronic pain-induced cognitive and psychiatric abnormalities. We have previously reported that LDN-212320, a glutamate transporter-1 (GLT-1) activator, attenuates complete Freund's adjuvant (CFA)-induced acute and chronic nociceptive pain. However, the cellular and molecular mechanisms underlying GLT-1 modulation in the hippocampus and ACC during chronic pain-induced cognitive deficit-like and anxiety-like behaviors remain unknown. Here, we have investigated the effects of LDN-212320 on CFA-induced chronic pain associated with cognitive deficit-like and anxiety-like behaviors in mice. We have evaluated the effects of LDN-212320 on CFA-induced impaired spatial, working, and recognition memory using Y-maze and object-place recognition tests. In addition, we have determined the effects of LDN-21230 on chronic pain-induced anxiety-like behaviors using elevated plus maze and marble burying test. We have also examined the effects of LDN-212320 on cAMP response element-binding protein (pCREB), brain-derived neurotrophic factor (BDNF), protein kinase A (PKA), and Ca2 +/calmodulin-dependent protein kinase II (CaMKII) expression in the hippocampus and ACC during CFA-induced cognitive deficit-like and anxiety-like behaviors using the Western blot analysis and immunofluorescence assay. Pretreatment with LDN-212320 (20 mg/kg) significantly attenuated CFA-induced impaired spatial, working, and recognition memory. Furthermore, LDN-212320 (20 mg/kg) significantly reduced CFA-induced anxiety-like behaviors. Additionally, LDN-212320 (20 mg/kg) significantly reversed CFA-induced decreased pCREB, BDNF, PKA and CaMKII expression in the hippocampus and ACC. Overall, these results suggest that the LDN-212320 prevents CFA-induced cognitive deficit-like and anxiety-like behaviors by activating CaMKII/CREB/BDNF signaling pathway in the hippocampus and ACC. Therefore, LDN-212320 could be a potential treatment for chronic pain associated with cognitive impairment and anxiety-like behaviors.

Identification of aberrant plasma vesicles containing AAK1 and CCDC18-AS1 in adolescents with major depressive disorder and preliminary exploration of treatment efficacy

BACKGROUND

Major depressive disorder (MDD) during adolescence significantly jeopardizes both mental and physical health. However, the etiology underlying MDD in adolescents remains unclear.

METHODS

A total of 74 adolescents with MDD and 40 health controls (HCs) who underwent comprehensive clinical and cognitive assessments were enrolled. Differential expression analysis was conducted on plasma extracellular vesicles (EVs) carrying long non-coding RNAs (lncRNAs) and messenger RNAs (mRNAs) by microarray analysis. Two possible lncRNA-miR-mRNA networks were established and candidate regulatory axes were generated using the StarBase, miRDB, and TargetScan bioinformatics databases. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the candidate molecules and signaling axes in a clinical cohort.

RESULTS

A total of 3752 dysregulated lncRNAs and 1789 dysfunctional mRNAs were identified. Two candidate regulatory axes (AC156455.1/miR-126-5p/AAK1 and CCDC18-AS1/miR-6835-5p/CCND2) with potential connections with MDD were selected. The candidate molecules exhibit differential expression patterns among adolescents with MDD and HCs, as well as before and after treatment with sertraline in adolescents with MDD. Furthermore, AAK1, CCDC18-AS1, and miR-6835-5p expressions exhibited significant differences between the response and non-response groups. Baseline expression of CCDC18-AS1, miR-6835-5p, and CCND2 could predict the therapeutic effect of sertraline, which may be associated with reducing suicidal ideation and improving cognitive function.

CONCLUSION

Our study may provide insights into the understanding of the underlying pathological mechanisms in adolescents with MDD.

Vanillic Acid Protects PC12 Cells from Corticosterone-Induced Neurotoxicity via Regulating Immune and Metabolic Dysregulation Based on Computational Metabolomics

Vanillic acid is widely used in the food industry and exhibits an excellent neuroprotective effect. Nevertheless, the mechanisms underlying them are largely unexplored, especially the interactions between the neuroprotection effects of vanillic acid and inflammation-immunity-metabolism. A cell metabolomics-based mathematics algorithm was reported to interpret the potential mechanism of vanillic acid on corticosterone-induced PC12 cells by regulating immune and metabolic dysregulation. Our results showed that vanillic acid markedly inhibited the level of inflammatory factors in corticosterone-induced PC12 cells. Cell metabolomics results suggested that vanillic acid regulated the abnormality of corticosterone-induced PC12 cell metabolic profiles and markedly regulated 11 differential metabolites. Our designed scoring model base entropy weight algorithm showed that the core targets (IL2RB, IFNA13, etc.) and metabolites (lactate, ethanolamine, etc.) regulate the immunity-metabolism of vanillic acid. Furthermore, we demonstrated that vanillic acid inhibited IL2RB expression and modulated the related pathway, JAK1/STAT3 signaling. The JAK inhibitor ABT-494 was further applied to validate the effect of vanillic acid on the JAK/STAT pathway. Results indicate that vanillic acid regulates the abnormal interactions of inflammation-immunity-metabolism by repressing the IL2RB-JAK1-STAT3 pathway. Methodologically, this study contributes to the decoding of vanillic acid's antidepressive effect from the metabolism perspective combined with computer algorithms and mathematics models.

Arctiin Mitigates Neuronal Injury by Modulating the P2X7R/NLPR3 Inflammasome Signaling Pathway

Depression, recognized globally as a primary cause of disability, has its pathogenesis closely related to neuroinflammation and neuronal damage. Arctiin (ARC), the major bioactive component of Fructus arctii, has various pharmacological activities, such as anti-inflammatory and neuroprotective effects. Building on previous findings that highlighted ARC's capability to mitigate depression by dampening microglial hyperactivation and thereby reducing neuroinflammatory responses and cortical neuronal damage in mice, the current study delves deeper into ARC's therapeutic potential by examining its impact on hippocampal neuronal damage in depression. Utilizing both chronic unpredictable mild stress (CUMS)-induced depression model in mice and corticosterone (CORT)-stimulated PC12 cell model of neuronal damage, the techniques including Nissl staining, immunohistochemistry, western blotting, ELISA, lactate dehydrogenase assays, colony formation assays, immunofluorescence staining and molecular docking were employed to unravel the mechanisms behind ARC's neuroprotective effects. The findings revealed that ARC not only mitigates hippocampal neuropathological damage and reduces serum CORT levels in CUMS-exposed mice but also enhances cell activity while reducing lactate dehydrogenase release in CORT-stimulated PC12 cells. ARC attenuated neuroinflammatory responses and neuronal apoptosis by inhibiting the overactivation of the P2X7 receptor (P2X7R)/NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome signaling pathway, similar to the effect of A438079 (P2X7R antagonist). Interestingly, pretreatment with A438079 blocked the neuroprotective effect of ARC. Computer modeling predicted that both ARC and A438079 have strong binding with P2X7R and they have the same binding site. These results suggested that ARC may exert a neuroprotective role by binding to P2X7R, thereby inhibiting the P2X7R/NLRP3 inflammasome signaling pathway.

Beyond PDE4 inhibition: A comprehensive review on downstream cAMP signaling in the central nervous system

Cyclic adenosine monophosphate (cAMP) is a key second messenger that regulates signal transduction pathways pivotal for numerous biological functions. Intracellular cAMP levels are spatiotemporally regulated by their hydrolyzing enzymes called phosphodiesterases (PDEs). It has been shown that increased cAMP levels in the central nervous system (CNS) promote neuroplasticity, neurotransmission, neuronal survival, and myelination while suppressing neuroinflammation. Thus, elevating cAMP levels through PDE inhibition provides a therapeutic approach for multiple CNS disorders, including multiple sclerosis, stroke, spinal cord injury, amyotrophic lateral sclerosis, traumatic brain injury, and Alzheimer's disease. In particular, inhibition of the cAMP-specific PDE4 subfamily is widely studied because of its high expression in the CNS. So far, the clinical translation of full PDE4 inhibitors has been hampered because of dose-limiting side effects. Hence, focusing on signaling cascades downstream activated upon PDE4 inhibition presents a promising strategy, offering novel and pharmacologically safe targets for treating CNS disorders. Yet, the underlying downstream signaling pathways activated upon PDE(4) inhibition remain partially elusive. This review provides a comprehensive overview of the existing knowledge regarding downstream mediators of cAMP signaling induced by PDE4 inhibition or cAMP stimulators. Furthermore, we highlight existing gaps and future perspectives that may incentivize additional downstream research concerning PDE(4) inhibition, thereby providing novel therapeutic approaches for CNS disorders.

Effect of Cerebralcare Granule® combined with memantine on Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

In elderly people, Alzheimer's disease (AD) is the most common form of dementia. It has been shown that traditional Chinese medicine (TCM) based on phytomedicines enhances the therapeutic effects of modern medicine when taken in conjunction with them. Modern medicine N-methyl-D-aspartate receptor (NMDA) antagonist memantine (Mm) are mainly used in the clinical treatment of AD. TCM Cerebralcare Granule® (CG) has long been an effective treatment for headaches, dizziness, and other symptoms. In this study, we employ a blend of CG and Mm to address Alzheimer's disease-like symptoms and explore their impacts and underlying mechanisms.

AIM OF THE STUDY

The objective of our study was to observe the effects of CG combined with Memantine (Mm) on learning and memory impairment of AD mice induced by D-galactose and to explore the mechanism at work.

MATERIALS AND METHODS

CG and Mm were combined to target multiple pathological processes involved in AD. For a thorough analysis, we performed various experiments such as behavioral detection, pathological detection, proteomic detection, and other experimental methods of detection.

RESULTS

It was found that the combination of CG and Mm was significantly effective for improving learning and memory in AD mice as well as brain pathology. The serum and hippocampal tissue of AD mice were significantly enhanced with catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA) levels were decreased with this treatment. In AD mice, a combination of Mm and CG (CG + Mm) significantly increased the levels of the anti-inflammatory factors IL-4 and IL-10, decreased the levels of pro-inflammatory factors (IL-6, IL-1β) and tumor necrosis factor-alpha (TNF-α), improved synaptic plasticity by restoring synaptophysin (SYP) and postsynaptic density protein-95 (PSD-95) expression in the hippocampus, enhanced Aβ phagocytosis of microglia in AD mice, and increased mitochondrial respiratory chain enzyme complexes I, II, III, and IV, lead to an increase in the number of functionally active NMDA receptors in the hippocampus. Proteomic analysis GO analysis showed that the positive regulation gene H3BIV5 of G protein coupled receptor signal pathway and synaptic transmission was up-regulated, while the transsynaptic signal of postsynaptic membrane potential and regulation-related gene Q5NCT9 were down-regulated. Most proteins showed significant enriched signal transduction pathway profiles after CG + Mm treatment, based on the KEGG pathway database.

CONCLUSION

The data supported the idea that CG and Mm could be more effective in treating AD mice induced by D-galactose than Mm alone. We provided a basis for the clinical use of CG with Mm.

Protective effect of hygrolansamycin C against corticosterone-induced toxicity and oxidative stress-mediated via autophagy and the MAPK signaling pathway

BACKGROUND

Excessive stress, a major problem in modern societies, affects people of all ages worldwide. Corticosterone is one of the most abundant hormones secreted during stressful conditions and is associated with various dysfunctions in the body. In particular, we aimed to investigate the protective effects of hygrolansamycin C (HYGC) against corticosterone-induced cellular stress, a manifestation of excessive stress prevalent in contemporary societies.

METHODS

We isolated HYGC from Streptomyces sp. KCB17JA11 and subjected PC12 cells to corticosterone-induced stress. The effects of HYGC were assessed by measuring autophagy and the expression of mitogen-activated protein kinase (MAPK) phosphorylation-related genes. We used established cellular and molecular techniques to analyze protein levels and pathways.

RESULTS

HYGC effectively protected cells against corticosterone-induced injury. Specifically, it significantly reduced corticosterone-induced oxidative stress and inhibited the expression of autophagy-related proteins induced by corticosterone, which provided mechanistic insight into the protective effects of HYGC. At the signaling level, HYGC suppressed c-Jun N-terminal kinase and extracellular signal-regulated kinase phosphorylation and p38 activation.

CONCLUSIONS

HYGC is a promising candidate to counteract corticosterone-induced apoptosis and oxidative stress. Autophagy and MAPK pathway inhibition contribute to the protective effects of HYGC. Our findings highlight the potential of HYGC as a therapeutic agent for stress-related disorders and serve as a stepping stone for further exploration and development of stress management strategies.

Kaempferol-3-O-sophoroside (PCS-1) contributes to modulation of depressive-like behaviour in C57BL/6J mice by activating AMPK

BACKGROUND AND PURPOSE

Kaempferol-3-O-sophoroside (PCS-1) is the main component in Crocus sativus (Saffron), a herb with mood-enhancing properties. AMP-activated protein kinase (AMPK) is a potential therapeutic target for depression. This study explores the antidepressive-like properties of PCS-1 and its AMPK activation to confirm AMPK as a target for antidepression.

EXPERIMENTAL APPROACH

Corticosterone (CORT)-induced PC12 cell injury served as an in vitro model to evaluate the neuroprotective effect of PCS-1. Neuro-2a cells and primary neurons were utilized to evaluate the synaptogenesis role of PCS-1. CORT-induced mouse depression model and chronic unpredictable mild stress (CUMS) model were used to assess the antidepressive-like properties of PCS-1 through behavioural tests, magnetic resonance imaging, and biochemical index measurements. Western blot and immunofluorescence assays were used to study the mechanisms of PCS-1. Cellular thermal shift assay was used to confirm the binding target.

KEY RESULTS

PCS-1 (12.5-50 μM) ameliorated CORT-induced PC12 cell damage, oxidative stress and inflammation. PCS-1 alone promoted an increase in synapses in Neuro-2a cells and primary neurons. Oral administration of PCS-1 (10 and 20 mg·kg-1 ) ameliorated weight loss, dyskinesia, and hippocampal volume reduction induced by CORT and CUMS. PCS-1 bound to AMPK to improve the expression of brain-derived neurotrophic factor (BDNF) and induce autophagy.

CONCLUSION AND IMPLICATIONS

PCS-1 binds to AMPK to promote BDNF production and autophagy enhancement, ultimately achieving antidepressant effects. This study provides support for the clinical application of saffron petals and provides further evidence for AMPK as a potential target for antidepression.

Hydrogen sulfide donor AP123 restores endothelial nitric oxide-dependent vascular function in hyperglycemia via a CREB-dependent pathway

Diabetes is associated with severe vascular complications involving the impairment of endothelial nitric oxide synthase (eNOS) as well as cystathionine γ-lyase (CSE) activity. eNOS function is suppressed in hyperglycaemic conditions, resulting in reduced NO bioavailability, which is paralleled by reduced levels of hydrogen sulfide (H₂S). Here we have addressed the molecular basis of the interplay between the eNOS and CSE pathways. We tested the impact of H₂S replacement by using the mitochondrial-targeted H₂S donor AP123 in isolated vessels and cultured endothelial cells in high glucose (HG) environment, at concentrations not causing any vasoactive effect per se. Aorta exposed to HG displayed a marked reduction of acetylcholine (Ach)-induced vasorelaxation that was restored by the addition of AP123 (10 nM). In HG condition, bovine aortic endothelial cells (BAEC) showed reduced NO levels, downregulation of eNOS expression, and suppression of CREB activation (p-CREB). Similar results were obtained by treating BAEC with propargylglycine (PAG), an inhibitor of CSE. AP123 treatment rescued eNOS expression, as well as NO levels, and restored p-CREB expression in both the HG environment and the presence of PAG. This effect was mediated by a PI3K-dependent activity since wortmannin (PI3K inhibitor) blunted the rescuing effects operated by the H₂S donor. Experiments performed in the aorta of CSE^-/- mice confirmed that reduced levels of H₂S not only negatively affect the CREB pathway but also impair Ach-induced vasodilation, significantly ameliorated by AP123. We have demonstrated that the endothelial dysfunction due to HG involves H₂S/PI3K/CREB/eNOS route, thus highlighting a novel aspect of the H₂S/NO interplay in the vasoactive response.

The role of peptidyl-prolyl isomerase Pin1 in neuronal signaling in epilepsy

Epilepsy is a common symptom of many neurological disorders and can lead to neuronal damage that plays a major role in seizure-related disability. The peptidyl-prolyl isomerase Pin1 has wide-ranging influences on the occurrence and development of neurological diseases. It has also been suggested that Pin1 acts on epileptic inhibition, and the molecular mechanism has recently been reported. In this review, we primarily focus on research concerning the mechanisms and functions of Pin1 in neurons. In addition, we highlight the significance and potential applications of Pin1 in neuronal diseases, especially epilepsy. We also discuss the molecular mechanisms by which Pin1 controls synapses, ion channels and neuronal signaling pathways to modulate epileptic susceptibility. Since neurotransmitters and some neuronal signaling pathways, such as Notch1 and PI3K/Akt, are vital to the nervous system, the role of Pin1 in epilepsy is discussed in the context of the CaMKII-AMPA receptor axis, PSD-95-NMDA receptor axis, NL2/gephyrin-GABA receptor signaling, and Notch1 and PI3K/Akt pathways. The effect of Pin1 on the progression of epilepsy in animal models is discussed as well. This information will lead to a better understanding of Pin1 signaling pathways in epilepsy and may facilitate development of new therapeutic strategies.

Potential Mechanisms of Shu Gan Jie Yu Capsule in the Treatment of Mild to Moderate Depression Based on Systemic Pharmacology and Current Evidence

Background

Shu Gan Jie Yu (SGJY) capsule has a good effect on relieving depressive symptoms in China. However, the mechanism of action is still unclear. Therefore, systemic pharmacology and molecular docking approaches were used to clarify its corresponding antidepressant mechanisms.

Methods

Traditional Chinese Medicine Database and Analysis Platform (TCMSP), the Encyclopedia of Traditional Chinese Medicine (ETCM), and Swiss Target Prediction servers were used to screen and predict the bioactive components of the SGJY capsule and their antidepressive targets. Mild to moderate depression (MMD) related genes were obtained from GeneCards and DisGeNET databases. A network of bioactive components-therapeutic targets of the SGJY capsule was established by STRING 11.5 and Cytoscape 3.9.0 software. Gene function and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed by utilizing Database for Annotation, Visualization, and Integrated Discovery (DAVID) platform. Active components were taken to dock with the hypothetical proteins by iGEMDOCK and SwissDock, and the docking details were visually displayed by UCSF Chimera software. Then, the related research literature of the SGJY capsule was reviewed, summarized, sorted, and analyzed, including experimental evidence and clinical experience.

Results

Seven active components and 45 intersection targets were included in the study. PPI network had genuinely uncovered the potential therapeutic targets, such as AKT1, HSP90AA1, ESR1, EGFR, and PTGS2. KEGG pathway analysis showed that the mechanism of the SGJY capsule on MMD was mainly involved in the PI3K-Akt signaling pathway.

Conclusions

In this study, we have successfully predicted the biochemically active constituents, potential therapeutic targets, and comprehensively predicted the related drug-gene interaction of the SGJY capsule for treating MMD and provided a basis for subsequent experiments.

Study on Antidepressant Effect and Mechanism of Crocin Mediated by the mTOR Signaling Pathway

Crocin is a monomer of Chinese traditional herbs extracted from saffron, relieving depression-like behavior. However, its underlying mechanism of action remains unclear. Herein, we explored whether crocin's antidepressant effect depended on the mammalian target of the rapamycin (mTOR) signaling pathway. The model of PC12 cells injury was established by corticosterone, the changes in cell survival rate were tested by the CCK-8 method, and the changes in cellular morphology were observed under a fluorescence microscope. The depression model was established by chronic unpredictable mild stress (CUMS), and its antidepressant effect was estimated by open field test (OFT), forced swimming test (FST), and tail suspension test (TST). Western blot was used to monitor the protein expression. The results showed that crocin could effectively improve cell survival rate and cellular synaptic growth, alleviate the depressive behavior of CUMS mice, and promote the expression of BDNF, P-mTOR, P-ERK, and PSD95. However, when rapamycin was pretreated, the antidepressant effects of crocin were inhibited. In summary, crocin plays a significant antidepressant effect. After pretreatment with rapamycin, the anti-depression effect of crocin was significantly inhibited. It is suggested that the mechanism of the anti-depression effect of crocin may be related to the mTOR signaling pathway.

Xiaoyaosan ethyl acetate fraction alleviates depression-like behaviors in CUMS mice by promoting hippocampal neurogenesis via modulating the IGF-1Rβ/PI3K/Akt signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaoyaosan (XYS), a representative and classic traditional Chinese medicine (TCM) prescription with function of dispersing stagnated liver and strengthening spleen, has been used for thousands of years to treat depression. XYS' anti-depression effect has been demonstrated both clinically and experimentally; however, the material basis for this effect has yet to be elucidated.

AIM OF THE STUDY

This study aimed to evaluate the impact and underlying action mechanism of XYS' antidepressant active component (Xiaoyaosan ethyl acetate fraction, XYSEF) against chronic unpredictable mild stress (CUMS)-induced depression-like behavior in mice.

MATERIALS AND METHODS

First, we established a behavioral despair depression mouse model to preliminarily determine the effective antidepressant dose of XYSEF. Then, we created a CUMS mouse model and used various classic behavioral tests, including SPT, ST, NFST, and TST, to assess XYSEF's antidepressant properties. IGF-1 levels in mouse serum and hippocampus were quantified using ELISA. The average optical density of Nissl bodies in the mouse hippocampal CA3 region was determined utilizing toluidine blue staining. Brdu and DCX expression in the hippocampal dentate gyrus (DG) was assayed using the immunofluorescence method. IGF-1Rβ, PI3K, p-PI3K, Akt, p-Akt, Caspase-3, and cleaved Caspase-3 protein levels in the hippocampus were determined with Western blot.

RESULTS

The behavioral despair mouse model findings showed that 9.1 and 40 g/kg of XYSEF both significantly shortened the immobility time of mice, suggesting that the effective dose range was 9.1-40 g/kg. Compared to the CUMS mouse model, XYSEF at 20 and 40 g/kg markedly increased the sucrose preference percentage in the SPT and grooming time in the ST, shortened the immobility time in the TST and the feeding latency in the NSFT, and reversed the downregulated IGF-1 content in mouse serum and hippocampus. In addition, XYSEF amplified the average optical density of Nissl bodies in the hippocampal CA3 region, promoted Brdu and DCX expression in DG, and diminished IGF-1Rβ, p-PI3K/PI3K, p-Akt/Akt, and cleaved Caspase-3/Caspase-3 protein levels in the hippocampi of CUMS mice.

CONCLUSION

XYSEF acted as an antidepressant in mice exhibiting CUMS-induced depression-like behaviors, possibly by promoting hippocampal neurogenesis, reducing neuronal apoptosis, and inhibiting the over-activation of the IGF-1Rβ/PI3K/Akt pathway.

Network Pharmacology and Molecular Docking Analyses of Mechanisms Underlying Effects of the Cyperi Rhizoma-Chuanxiong Rhizoma Herb Pair on Depression

OBJECTIVE

We aimed to investigate the mechanisms underlying the effects of the Cyperi Rhizoma-Chuanxiong Rhizoma herb pair (CCHP) against depression using a network pharmacology approach.

METHODS

A network pharmacology approach, including screening of active compounds, target prediction, construction of a protein-protein interaction (PPI) network, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, and molecular docking, molecular dynamics (MD) simulations, and molecular mechanics Poisson-Boltzmann surface area (MMPBSA), were used to explore the mechanisms of CCHP against depression.

RESULTS

Twenty-six active compounds and 315 and 207 targets of CCHP and depression, respectively, were identified. The PPI network suggested that AKT1, IL-6, TP53, DRD2, MAPK1, NR3C1, TNF, etc., were core targets. GO enrichment analyses showed that positive regulation of transcription from RNA polymerase II promoter, plasma membrane, and protein binding were of great significance. Neuroactive ligand-receptor interaction, PI3K-Akt signaling pathway, dopaminergic synapse, and mTOR signaling pathway were important pathways. Molecular docking results revealed good binding affinities for the core compounds and core targets. MD simulations and MMPBSA validated that quercetin can stably bind to 6hhi.

CONCLUSIONS

The effects of CCHP against depression involve multiple components, targets, and pathways, and these findings will promote further research on and clinical application of CCHP.

Hederagenin Protects PC12 Cells Against Corticosterone-Induced Injury by the Activation of the PI3K/AKT Pathway

Depression is a prevalent psychiatric disorder and a leading cause of disability worldwide. Despite a variety of available treatments currently being used in the clinic, a substantial proportion of patients is unresponsive to these treatments, urging the development of more effective therapeutic approaches. Hederagenin (Hed), a triterpenoid saponin extracted from Fructus Akebiae, has several biological activities including anti-apoptosis, anti-hyperlipidemic and anti-inflammatory properties. Over the years, its potential therapeutic effect in depression has also been proposed, but the information is limited and the mechanisms underlying its antidepressant-like effects are unclear. The present study explored the neuroprotective effects and the potential molecular mechanisms of Hederagenin action in corticosterone (CORT)-injured PC12 cells. Obtained results show that Hederagenin protected PC12 cells against CORT-induced damage in a concentration dependent manner. In adittion, Hederagenin prevented the decline of mitochondrial membrane potential, reduced the production of intracellular reactive oxygen species (ROS) and decreased the apoptosis induced by CORT. The protective effect of Hederagenin was reversed by a specific phosphatidylinositol-3-kinase (PI3K) inhibitor LY294002 and AKT (also known as protein kinase B) inhibitor MK2206, suggesting that the effect of Hederagenin is mediated by the PI3K/AKT pathway. In line with this, western blot analysis results showed that Hederagenin stimulated the phosphorylation of AKT and its downstream target Forkhead box class O 3a (FoxO3a) and Glycogen synthase kinase-3-beta (GSK3β) in a concentration dependent manner. Taken together, these results indicate that the neuroprotective effect of Hederagenin is likely to occur via stimulation of the PI3K/AKT pathway.

Fluoxetine and environmental enrichment similarly reverse chronic social stress-related depression- and anxiety-like behavior, but have differential effects on amygdala gene expression

The adverse effects of stress on brain and behavior have long been known and well-studied, with abundant evidence linking stress to, among other things, mood and anxiety disorders. Likewise, many have investigated potential treatments for stress-related mood and anxiety phenotypes and demonstrated good response to standard antidepressant medications like selective serotonin reuptake inhibitors (SSRIs), as well as environmental manipulations like exercise or enrichment. However, the extent to which stress and various treatments act on overlapping pathways in the brain is less well understood. Here, we used a widely studied social defeat stress paradigm to induce a robust depression- and anxiety-like phenotype and chronic corticosterone elevation that persisted for at least 4 weeks in wild type male mice. When mice were treated with either the SSRI fluoxetine or an enriched environment, both led to similar behavioral recovery from social defeat. We then focused on the amygdala and assessed the effects of social defeat, fluoxetine, and enrichment on 168 genes broadly related to synaptic plasticity or oxidative stress. We found 24 differentially expressed genes in response to social defeat stress. Interestingly, fluoxetine led to broad normalization of the stress-induced expression pattern while enrichment led to expression changes in a separate set of genes. Together, this study provides additional insight into the chronic effects of social defeat stress on behavior and gene expression in the amygdala. The findings also suggest that, for a subset of genes assessed, fluoxetine and environmental enrichment have strikingly divergent effects on expression in the amygdala, despite leading to similar behavioral outcomes.

GABAB receptor intracellular signaling: novel pathways for depressive disorder treatment?

Affecting over 320 million people around the world, depression has become a formidable challenge for modern medicine. In addition, an increasing number of studies cast doubt on the monoamine theory of depressive disorder and, worryingly, antidepressant medications only significantly benefit patients with severe depression. Thus, it is not surprising that researchers have shown an increased interest in new theories attempting to explain the pathogenesis of this disease. One example is the excitatory/inhibitory transmission imbalance theory. These abnormalities involve glutamate and γ-aminobutyric acid (GABA) signaling. Studies on GABA_B receptors and their antagonists are particularly promising for the treatment of depressive disorders. In this paper, intracellular pathways controlled by GABA_B receptors and their links to depression are described, including the impact of ketamine on GABAergic synaptic transmission.

Specific Akt Family Members Impair Stress-Mediated Transactivation of Viral Promoters and Enhance Neuronal Differentiation: Important Functions for Maintaining Latency

Neurotropic Alphaherpesvirinae subfamily members such as bovine herpesvirus 1 (BoHV-1) and herpes simplex virus 1 (HSV-1) establish and maintain lifelong latent infections in neurons. Following infection of ocular, oral, or nasal cavities, sensory neurons within trigeminal ganglia (TG) are an important site for latency. Certain external stressors can trigger reactivation from latency, in part because activation of the glucocorticoid receptor (GR) stimulates productive infection and promoters that drive expression of key viral transcriptional regulators. The Akt serine/threonine protein kinase family is linked to maintaining latency. For example, Akt3 is detected in more TG neurons during BoHV-1 latency than in reactivation and uninfected calves. Furthermore, Akt signaling correlates with maintaining HSV-1 latency in certain neuronal models of latency. Finally, an active Akt protein kinase is crucial for the ability of the HSV-1 latency-associated transcript (LAT) to inhibit apoptosis in neuronal cell lines. Consequently, we hypothesized that viral and/or cellular factors impair stress-induced transcription and reduce the incidence of reactivation triggered by low levels of stress. New studies demonstrate that Akt1 and Akt2, but not Akt3, significantly reduced GR-mediated transactivation of the BoHV-1 immediate early transcription unit 1 (IEtu1) promoter, the HSV-1 infected cell protein 0 (ICP0) promoter, and the mouse mammary tumor virus long terminal repeat (MMTV-LTR). Akt3, but not Akt1 or Akt2, significantly enhanced neurite formation in mouse neuroblastoma cells, which correlates with repairing damaged neurons. These studies suggest that unique biological properties of the three Akt family members promote the maintenance of latency in differentiated neurons.IMPORTANCE External stressful stimuli are known to increase the incidence of reactivation of Alphaherpesvirinae subfamily members. Activation of the glucocorticoid receptor (GR) by the synthetic corticosteroid dexamethasone (DEX) stimulates bovine herpesvirus 1 (BoHV-1) and herpes simplex virus 1 (HSV-1) reactivation. Furthermore, GR and dexamethasone stimulate productive infection and promoters that drive expression of viral transcriptional regulators. These observations lead us to predict that stress-induced transcription is impaired by factors abundantly expressed during latency. Interestingly, activation of the Akt family of serine/threonine protein kinases is linked to maintenance of latency. New studies reveal that Akt1 and Ak2, but not Akt3, impaired GR- and dexamethasone-mediated transactivation of the BoHV-1 immediate early transcription unit 1 and HSV-1 ICP0 promoters. Strikingly, Akt3, but not Akt1 or Akt2, stimulated neurite formation in mouse neuroblastoma cells, a requirement for neurogenesis. These studies provide insight into how Akt family members may promote the maintenance of lifelong latency.

Liquiritin protects PC12 cells from corticosterone-induced neurotoxicity via regulation of metabolic disorders, attenuation ERK1/2-NF-κB pathway, activation Nrf2-Keap1 pathway, and inhibition mitochondrial apoptosis pathway

Liquiritin, a flavone derived from the medicine food homology plant liquorice, possesses neuroprotective. However, the neuroprotective mechanism is not clear. In this study, metabolomics based LC-MS was performed to discover the metabolite changes in PC12 cells treated with corticosterone-induced neurotoxicity after liquiritin treatment. A total of 30 metabolites were identified as differential metabolites. Among them, 11 metabolites were regulated by liquiritin, and involved in the D-glutamine and D-glutamate metabolism, and glutathione metabolism, etc. Based on the results of metabolomics, three cell signaling pathways related to these metabolic pathways were verified. The results showed that the ERK1/2-NF-κB pathway related to the D-glutamine and D-glutamate metabolism was attenuated by liquiritin via down-regulation phospho-ERK1/2, phospho-IκBα, phospho-NF-κB protein expression levels. Furthermore, the Nrf2-Keap1 pathway related to glutathione metabolism was activated by liquiritin via up-regulation Nrf2, Keap1, HO-1, NQO1 protein expression levels, and increased SOD, CAT, GSH-PX enzyme activity, thus exerting antioxidant activity. Additionally, liquiritin inhibited the mitochondrial apoptosis by decreasing the Ca²⁺ concentration, improving MMP, up-regulating Bcl-2, and down-regulating Bax, cytochrome C, cleaved-Caspase-3 expression levels. These results suggest that the neuroprotective mechanisms of liquiritin are connected to the regulation of metabolic disorders, activation Nrf2/Keap1 pathway, attenuation ERK1/2/NF-κB pathway, and inhibition mitochondrial apoptosis pathway.

Identification of the significant pathways of Banxia Houpu decoction in the treatment of depression based on network pharmacology

Banxia Houpu decoction (BXHPD) has been used to treat depression in clinical practice for centuries. However, the pharmacological mechanisms of BXHPD still remain unclear. Network Pharmacology (NP) approach was used to explore the potential molecular mechanisms of BXHPD in treating depression. Potential active compounds of BXHPD were obtained from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform Database. STRING database was used to build a interaction network between the active compounds and target genes associated with depression. The topological features of nodes were visualized and calculated. Significant pathways and biological functions were identified using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses. A total of 44 active compounds were obtained from BXHPD, and 121 potential target genes were considered to be therapeutically relevant. Pathway analysis indicated that MAPK signaling pathway, ErbB signaling pathway, HIF-1 signaling pathway and PI3K-Akt pathway were significant pathways in depression. They were mainly involved in promoting nerve growth and nutrition and alleviating neuroinflammatory conditions. The result provided some potential ways for modern medicine in the treatment of depression.

Fluoxetine exposure for more than 2 days decreases the neuronal plasticity mediated by CRMP2 in differentiated PC12 cells

BACKGROUND

Recent studies indicate that antidepressants treatment restores neuronal plasticity. In contrast, some researchers claim that serotonergic antidepressants, including fluoxetine (FLU), may exacerbate neuronal plasticity, which is contradictory and rarely studied. Since almost those studies exposed cells with drugs for 1-2 days as treatment models of antidepressants, it is possible that FLU exposure for longer periods would have opposite effects on neuronal plasticity.

RESULTS

In the present study, we examined the effects of FLU exposure (up to 3 days) on the neuronal plasticity in differentiated PC12 cells. The cell viability shown a slight decrease at day 2 (93.5 ± 3.5 %), followed by a highly significant decrease at day 3(71.4 ± 4.4 %). As previously reported, neuronal plasticity was significantly upregulated by FLU exposure at day 1. However, the neurite length, activity-regulated cytoskeleton-associated protein (Arc) and c-Fos mRNA were inhibited with FLU exposure at day 3. Similarly, the expression of tubulin, which play important roles in the neuronal plasticity, was the same result. Furthermore, we found α-tubulin interacted with collapsing response mediator protein 2(CRMP2), which is related to neuronal plasticity, and the regulation of CRMP2 activity influenced the neurite length, Arc, c-Fos and tubulin expression.

CONCLUSIONS

The results demonstrated that neuronal plasticity was increased by FLU exposure at day 1, but exposure with FLU for more than 2 days had opposite effect on it. The reduction in neuronal plasticity with FLU exposure for more than 2 days might be involved in some aspects of the therapeutic effect of antidepressant on depression.

Upregulation of antioxidant thioredoxin by antidepressants fluoxetine and venlafaxine

RATIONALE

Selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are the most commonly used drugs for the treatment of depression. Studies have shown that chronic treatment with SSRIs and SNRIs produces a protective effect against oxidative stress. Thioredoxin (Trx) is an antioxidant protein that reverses protein cysteine oxidation and facilitates scavenging reactive oxygen species.

OBJECTIVES

The current study is to determine whether the SSRI fluoxetine and the SNRI venlafaxine regulate Trx and protect neuronal cells against protein cysteine oxidation.

METHODS

HT22 mouse hippocampal cells were incubated with fluoxetine or venlafaxine for 5 days. Protein levels of Trx, Trx reductase (TrxR), and Trx-interacting protein (Txnip) were measured by immunoblotting analysis. Trx and TrxR activities were analyzed by spectrophotometric method. Protein cysteine sulfenylation was measured by dimedone-conjugation assay, while nitrosylation was measured by biotin-switch assay.

RESULTS

We found that treatment with fluoxetine or venlafaxine for 5 days increased Trx and TrxR protein levels but produced no effect on Txnip protein levels. These treatments also increased Trx and TrxR activities. Although treatment with fluoxetine or venlafaxine alone had no effect on sulfenylated and nitrosylated protein levels, both drugs inhibited H₂O₂-increased sulfenylated protein levels and nitric oxide donor nitrosoglutathione-increased nitrosylated protein levels. Stress increases risk of depression. We also found that treatment with fluoxetine or venlafaxine for 5 days inhibited stress hormone corticosterone-increased total sulfenylated and nitrosylated protein levels.

CONCLUSIONS

Our findings suggest that chronic treatment with antidepressants may upregulate Trx, subsequently inhibiting protein sulfenylation and nitrosylation, which may contribute to the protective effect of antidepressants against oxidative stress. Our findings also indicate that thioredoxin is a potential therapeutic target for the treatment of depression.

Corticosterone induces neurotoxicity in PC12 cells via disrupting autophagy flux mediated by AMPK/mTOR signaling

Aims

Our previous study indicated that chronic stress caused autophagy impairment and subsequent neuron apoptosis in hippocampus. However, the mechanism underlying the stress‐induced damage to neurons is unclear. In present work, we investigated whether stress‐level glucocorticoids (GCs) GCs promoted PC12 cell damage via AMPK/mTOR signaling‐mediated autophagy.

Methods

Chronic stress‐induced PC12 cell injury model was built by treatment with high level corticosterone (CORT). Cell injury was evaluated by flow cytometry assay and transmission electron microscopy observation.

Results

Autophagy flux was measured based on the changes in LC3‐II and P62 protein expressions, and the color alteration of mCherry‐GFP‐LC3‐II transfection. Our results showed that CORT not only increased cell injury and apoptosis, but also dysregulated AMPK/mTOR signaling‐mediated autophagy flux, as indicated by the upregulated expression of LC3‐II and P62 proteins, and the lowered ration of autolysosomes to autophagosomes. Mechanistically, our results demonstrated that autophagy activation by AMPK activator metformin or mTOR inhibitor rapamycin obviously promotes cell survival and autophagy flux, improved mitochondrial ultrastructure, and reduced expression of Cyt‐C and caspase‐3 in CORT‐induced PC12 cells.

Conclusion

These results indicate that high CORT triggers PC12 cell damage through disrupting AMPK/mTOR‐mediated autophagy flux. Targeting this signaling may be a promising approach to protect against high CORT and chronic stress‐induced neuronal impairment.

Inhibition of FOXO3a/BIM signaling pathway contributes to the protective effect of salvianolic acid A against cerebral ischemia/reperfusion injury

Salvianolic acid A (SalA) is an effective compound extracted from traditional Chinese medicine Salvia miltiorrhiza Bunge. The Forkhead box O3a (FOXO3a) signaling pathway plays crucial roles in the modulation of ischemia-induced cell apoptosis. However, no information about the regulatory effect of SalA on FoxO3a is available. To explore the anti-cerebral ischemia effect and clarify the therapeutic mechanism of SalA, SH-SY5Y cells and Sprague–Dawley rats were applied, which were exposed to oxygen glucose deprivation/reoxygenation (OGD/R) and middle cerebral artery occlusion/reperfusion (MCAO/R) injuries, respectively. The involved pathway was identified using the specific inhibitor LY294002. Results showed that SalA concentration-dependently inhibited OGD/R injury triggered cell viability loss. SalA reduced cerebral infarction, lowered brain edema, improved neurological function, and inhibited neuron apoptosis in MCAO/R rats, which were attenuated by the treatment of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) specific inhibitor LY294002. SalA time- and concentration-dependently upregulated the phosphorylation levels of protein kinase B (AKT) and its downstream protein FOXO3a. Moreover, the nuclear translocation of FOXO3a was inhibited by SalA both in vivo and in vitro, which was also reversed by LY294002. The above results indicated that SalA fought against ischemia/reperfusion damage at least partially via the AKT/FOXO3a/BIM pathway.

Animal models of major depressive disorder and the implications for drug discovery and development

INTRODUCTION

Depression is a highly debilitating psychiatric disorder that affects the global population and causes severe disabilities and suicide. Depression pathogenesis remains poorly understood, and the disorder is often treatment-resistant and recurrent, necessitating the development of novel therapies, models and concepts in this field. Areas covered: Animal models are indispensable for translational biological psychiatry, and markedly advance the study of depression. Novel approaches continuously emerge that may help untangle the disorder heterogeneity and unclear categories of disease classification systems. Some of these approaches include widening the spectrum of model species used for translational research, using a broader range of test paradigms, exploring new pathogenic pathways and biomarkers, and focusing more closely on processes beyond neural cells (e.g. glial, inflammatory and metabolic deficits). Expert opinion: Dividing the core symptoms into easily translatable, evolutionarily conserved phenotypes is an effective way to reevaluate current depression modeling. Conceptually novel approaches based on the endophenotype paradigm, cross-species trait genetics and 'domain interplay concept', as well as using a wider spectrum of model organisms and target systems will enhance experimental modeling of depression and antidepressant drug discovery.

TPPU, a sEH Inhibitor, Attenuates Corticosterone-Induced PC12 Cell Injury by Modulation of BDNF-TrkB Pathway

High level of corticosterone (CORT) is toxic to neurons and plays an important role in depression-like behavior and chronic stress. Our previous study showed that TPPU, a soluble epoxide hydrolase (sEH) inhibitor (sEHI), induces an antidepressant effect in animal models. However, the underlying mechanism is not clear. In this study, we investigated the protective effect of TPPU on PC12 cells against CORT-induced cytotoxicity and its underlying mechanism. We found that TPPU and the sEH substrate epoxyeicosatrienoic acids (EETs) protected PC12 cells from the CORT-induced injury by increasing cell viability and inhibiting apoptosis. Furthermore, TPPU and EETs also blocked the CORT-mediated downregulation of BDNF. Blocking the BDNF-TrkB pathway by the TrkB inhibitor K252a abolished the protective effect of TPPU. Taken together, our results suggest that sEHI could protect PC12 cells against the CORT-induced cytotoxicity via the BDNF-TrkB signaling pathway.

Protective effects of macamides from Lepidium meyenii Walp. against corticosterone-induced neurotoxicity in PC12 cells

Maca has attracted considerable attention owing to its neuroprotective effects in vitro and vivo. Macamides, a series of nonpolar and long-chain fatty acid N-benzylamides, are considered unique constituents in maca. This study investigated the protective effects of ethanol extracts of maca (EEM) and macamides on corticosterone-induced (CORT) neurotoxicity in rat pheochromocytoma (PC12) cells. CORT reduced cell viability and increased LDH release, intracellular ROS levels, and MMP decline rate, and induced mitochondrial apoptosis. However, pretreatment with EEM and macamides ameliorated CORT-induced neurotoxicity. EEM increased the cell viability and reduced the LDH release. M 18:1, M 18:2, and M 18:3 increased cell viability and reduced LDH release and intracellular ROS generation. M 18:2 and M 18:3 inhibited MMP reduction and reduced the Bax/Bcl-2 ratios. M 18:1 reduced the intracellular ROS without affecting other factors. Moreover, M 18:3 prevented CORT-induced mitochondrial apoptosis, restrained the expression levels of pro-apoptotic proteins, namely, Bax, cytochrome C, cleaved-caspase-3, and cleaved-PARP, and increased the expression levels of Bcl-2. In addition, M 18:3 increased Akt phosphorylation and the ability of M 18:3 to protect against CORT-induced cytotoxicity was remarkably reduced by LY294002, a PI3K phosphorylation inhibitor. M 18:3 also elevated the phosphorylation of CREB and activated the BDNF protein levels in CORT-induced PC12 cells. In conclusion, macamides, especially M 18:3, exert protective effects on CORT-induced PC12 cells. The cellular mechanism of M 18:3 against CORT-induced cytotoxicity may involve inhibition of mitochondrial apoptosis, and activation of Akt and CREB phosphorylation. Overall, macamides may potentially treat neuronal damage induced by CORT.

Neuroprotection of macamides is probably associated with inhibition of the mitochondrial apoptotic and the activation of the phosphorylation of Akt and CREB.

Behavioral defects induced by chronic social defeat stress are protected by Momordica charantia polysaccharides via attenuation of JNK3/PI3K/AKT neuroinflammatory pathway

Background

The aim of this study was to evaluate the protective effects of Momordica charantia polysaccharides (MCP) on depressive-like behaviors.

Methods

The chronic social defeat stress (CSDS) mice model was used to evaluate the effects of MCP and their underlying mechanisms. Social interaction test (SIT), sucrose preference test (SPT), and tail suspension test (TST) were performed for behavioral assessments. Expression levels of inflammation mediators and phosphatidylinositol 3-kinase (PI3K) activity were determined using commercial ELISA kits. The expression of key proteins in the c-Jun N-terminal protein kinase (JNK3)/PI3K/protein kinase B (AKT) pathway were measured using western blot and RT-PCR.

Results

The results showed that chronic administration of MCP (100, 200, 400 mg/kg/day) significantly prevented depressive-like behaviors in CSDS mice as assessed by SIT, TST and SPT. Elevated levels of proinflammatory cytokines [tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β)], and expression of JNK3, c-Jun, P-110β proteins were observed in the hippocampus of CSDS mice. Moreover, the activity of PI3K and phosphorylation level of AKT were reduced in the hippocampus of CSDS mice. Interestingly, the administration of MCP reversed these changes. Furthermore, the protective effects of MCP on CSDS mice were partly inhibited by the PI3K inhibitor, LY294002.

Conclusions

In conclusion, the protective effects of MCP against depressive-like behaviors in CSDS mice might be due to a reduction in neuroinflammation and the down-regulation of the JNK3/PI3K/AKT pathway in the hippocampus.

Inhibition of Phosphodiesterase 4 by FCPR03 Alleviates Chronic Unpredictable Mild Stress-Induced Depressive-Like Behaviors and Prevents Dendritic Spine Loss in Mice Hippocampi

BACKGROUND

Phosphodiesterase 4 is a promising target for developing novel antidepressants. However, prototype phosphodiesterase 4 inhibitors show severe side effects, including nausea and vomiting. N-Isopropyl-3-(cyclopropylmethoxy)-4-difluoromethoxy benzamide (FCPR03) is a novel phosphodiesterase 4 inhibitor with little emetic potential. In the present study, we investigated the inhibitory effect of FCPR03 on chronic unpredictable mild stress-induced, depressive-like behaviors in mice and explored the underlying mechanisms.

METHODS

The depression model of mice was established by chronic unpredictable mild stress. Forced swim test, tail suspension test, and sucrose preference test were used to assess depressive-like behaviors. Golgi-staining was utilized to analyze dendritic morphology and spine density. The level of cAMP was measured by enzyme-linked immnosorbent assay assay. Western blot was used to evaluate protein levels of phosphorylated cAMP-response element binding protein, protein kinase B, glycogen synthase kinase-3β, and brain derived neurotrophic factor in both hippocampus and prefrontal cortex. Postsynaptic density protein 95 and synapsin 1 were also detected by western blot in the hippocampi.

RESULTS

Treatment with FCPR03 (0.5-1.0 mg/kg, i.p.) increased consumption of sucrose in the sucrose preference test in mice exposed to chronic unpredictable mild stress. FCPR03 shortened the immobility time in forced swim test and tail suspension test without affecting locomotor activity. Furthermore, chronic unpredictable mild stress decreased the dendritic spine density and dendritic length in the hippocampus. This change was accompanied by decreased expression of postsynaptic density protein 95 and synapsin 1. Interestingly, FCPR03 prevented dendritic spine loss and increased synaptic protein levels. Moreover, the levels of cAMP, phosphorylated cAMP-response element binding protein, and brain derived neurotrophic factor were elevated in chronic unpredictable mild stress-challenged mice after treatment with FCPR03. In addition, FCPR03 also enhanced the phosphorylation of both protein kinase B and glycogen synthase kinase-3β in mice exposed to chronic unpredictable mild stress.

CONCLUSION

The present study suggests that FCPR03 could prevent both depressive-like behaviors and spine loss induced by chronic unpredictable mild stress in the mice hippocampi.

Tanshinone IIA Attenuates Insulin Like Growth Factor 1 -Induced Cell Proliferation in PC12 Cells through the PI3K/Akt and MEK/ERK Pathways

The insulin like growth factor 1 (IGF-1) and its receptor (IGF-1R) facilitate tumor proliferation and progression. Tanshinone IIA (TSN) is an active diterpene quinone isolated from the roots of the herbal plant Salvia miltiorrhiza. TSN inhibits the proliferation of various types of cancer cells but its role in the IGF-1R-induced proliferation of pheochromocytoma (PC12) cells and the potential mechanisms are largely unknown. This study aims to investigate the anti-proliferative effect of TSN in PC12 cells and its role on IGF-1R signaling transduction. PC12 cells were treated with IGF-1 with or without TSN, methyl thiazolytetrazolium (MTT) assay, and cell counting kit-8 and flow cytometry were used to evaluate the proliferation of PC12 cells. The role of TSN on the apoptosis of PC12 cells were detected by flow cytometry as well. The effects of TSN and IGF-1 on the phosphorylation of IGF-1R, protein kinase B (Akt), extracellular-signal related kinase 1/2 (ERK1/2) and other downstream targets were analyzed by Western blotting analysis. Our results showed that IGF-1 promoted the growth of PC12 cells in a dose-dependent manner and increased the phosphorylation of IGF-1R, whereas TSN attenuated the effect of IGF-1. Interestingly, TSN did not induce cell apoptosis in PC12 cells. Moreover, TSN attenuated the phosphorylation of Akt and ERK1/2 induced by IGF-1, and the phosphorylation of glycogen synthase kinase-3β, forkhead box O3a (FOXO3a) and c-Raf were also inhibited by TSN. Furthermore, TSN inhibited cell growth induced by IGF-1 and blocked the activation of IGF-1R in SH-SY5Y cells. Taken together, TSN has an inhibitory effect on the proliferation of PC12 cells via down-regulation of the phosphorylated IGF-1R and its downstream signaling.

Involvement of Akt/CREB signaling pathways in the protective effect of EPA against interleukin-1β-induced cytotoxicity and BDNF down-regulation in cultured rat hippocampal neurons

BACKGROUND

Our published data have indicated that the omega-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) provides beneficial effects by attenuating neuronal damage induced by interleukin-1β (IL-1β), and up-regulation of the expression of brain-derived neurotrophic factor (BDNF) represents a crucial part in the neuroprotective effect of EPA. However, the mechanisms of how EPA regulates BDNF expression remains incompletely understood. The present study investigated the role of Akt/CREB signaling in the effect of EPA on BDNF expression and its neuroprotective effect.

RESULTS

The present results showed that IL-1β reduced hippocampal neuronal viability and that EPA showed a concentration-dependent neuroprotective effect, but the neuroprotective effects of EPA were abolished by inhibition of Akt using KRX-0401, an inhibitor of Akt. Treatment of hippocampal neurons with EPA also ameliorated the decrease in Akt and CREB phosphorylation induced by IL-1β and BDNF down-regulation mediated by IL-1β. However, inhibition of Akt reversed the effect of EPA on levels of p-Akt, p-CREB, and BDNF.

CONCLUSIONS

Our data indicate that EPA elicited neuroprotection toward IL-1β-induced cell damage and BDNF decrease and that its effects potentially occurred via the Akt/CREB signaling pathway.

cAMP Response Element-Binding Protein (CREB): A Possible Signaling Molecule Link in the Pathophysiology of Schizophrenia

Dopamine is a brain neurotransmitter involved in the pathology of schizophrenia. The dopamine hypothesis states that, in schizophrenia, dopaminergic signal transduction is hyperactive. The cAMP-response element binding protein (CREB) is an intracellular protein that regulates the expression of genes that are important in dopaminergic neurons. Dopamine affects the phosphorylation of CREB via G protein-coupled receptors. Neurotrophins, such as brain derived growth factor (BDNF), are critical regulators during neurodevelopment and synaptic plasticity. The CREB is one of the major regulators of neurotrophin responses since phosphorylated CREB binds to a specific sequence in the promoter of BDNF and regulates its transcription. Moreover, susceptibility genes associated with schizophrenia also target and stimulate the activity of CREB. Abnormalities of CREB expression is observed in the brain of individuals suffering from schizophrenia, and two variants (-933T to C and -413G to A) were found only in schizophrenic patients. The CREB was also involved in the therapy of animal models of schizophrenia. Collectively, these findings suggest a link between CREB and the pathophysiology of schizophrenia. This review provides an overview of CREB structure, expression, and biological functions in the brain and its interaction with dopamine signaling, neurotrophins, and susceptibility genes for schizophrenia. Animal models in which CREB function is modulated, by either overexpression of the protein or knocked down through gene deletion/mutation, implicating CREB in schizophrenia and antipsychotic drugs efficacy are also discussed. Targeting research and drug development on CREB could potentially accelerate the development of novel medications against schizophrenia.

Mechanisms and Therapeutic Targets of Depression After Intracerebral Hemorrhage

The relationship between depression and intracerebral hemorrhage (ICH) is complicated. One of the most common neuropsychiatric comorbidities of hemorrhagic stroke is Post-ICH depression. Depression, as a neuropsychiatric symptom, also negatively impacts the outcome of ICH by enhancing morbidity, disability, and mortality. However, the ICH outcome can be improved by antidepressants such as the frequently-used selective serotonin reuptake inhibitors. This review therefore presents the mechanisms of post-ICH depression, we grouped the mechanisms according to inflammation, oxidative stress (OS), apoptosis and autophagy, and explained them through their several associated signaling pathways. Inflammation is mainly related to Toll-like receptors (TLRs), the NF-kB mediated signal pathway, the PPAR-γ-dependent pathway, as well as other signaling pathways. OS is associated to nuclear factor erythroid-2 related factor 2 (Nrf2), the PI3K/Akt pathway and the MAPK/P38 pathway. Moreover, autophagy is associated with the mTOR signaling cascade and the NF-kB mediated signal pathway, while apoptosis is correlated with the death receptor-mediated apoptosis pathway, mitochondrial apoptosis pathway, caspase-independent pathways and others. Furthermore, we found that neuroinflammation, oxidative stress, autophagy, and apoptosis experience interactions with one another. Additionally, it may provide several potential therapeutic targets for patients that might suffer from depression after ICH.

Roflupram, a Phosphodiesterase 4 Inhibitior, Suppresses Inflammasome Activation through Autophagy in Microglial Cells

Inhibition of phosphodiesterase 4 (PDE4) suppressed the inflammatory responses in the brain. However, the underlying mechanisms are poorly understood. Roflupram (ROF) is a novel PDE4 inhibitor. In the present study, we found that ROF enhanced the level of microtubule-associated protein 1 light chain 3 II (LC3-II) and decreased p62 in microglial BV-2 cells. Enhanced fluorescent signals were observed in BV-2 cells treated with ROF by Lysotracker red and acridine orange staining. In addition, immunofluorescence indicated a significant increase in punctate LC3. Moreover, β amyloid 25-35 (Aβ_25-35) or lipopolysaccharide (LPS) with ATP was used to activate inflammasome. We found that both LPS plus ATP and Aβ_25-35 enhanced the conversion of pro-caspase-1 to cleaved-caspase-1 and increased the production of mature IL-1β in BV-2 cells. Interestingly, these effects were blocked by the treatment of ROF. Consistently, knocking down the expression of PDE4B in primary microglial cells led to enhanced level of LC-3 II and decreased activation of inflammasome. What's more, Hoechst staining showed that ROF decreased the apoptosis of neuronal N2a cells in conditioned media from microglia. Our data also showed that ROF dose-dependently enhanced autophagy, reduced the activation of inflammasome and suppressed the production of IL-1β in mice injected with LPS. These effects were reversed by inhibition of microglial autophagy. These results put together demonstrate that ROF inhibits inflammasome activities and reduces the release of IL-1β by inducing autophagy. Therefore, ROF could be used as a potential therapeutic compound for the intervention of inflammation-associated diseases in the brain.

Alleviative effects of fluoxetine on depressive-like behaviors by epigenetic regulation of BDNF gene transcription in mouse model of post-stroke depression

Fluoxetine, one of the selective serotonin reuptake inhibitor (SSRI) antidepressants, has been thought to be effective for treating post-stroke depression (PSD). Recent work has shown that fluoxetine may exert an antidepressive effect through increasing the level of brain-derived neurotrophic factor (BDNF), but the underlying mechanism still remains unclear. In the present study, we successfully established the PSD model using male C57BL/6 J mice by photothrombosis of the left anterior cortex combined with isolatied-housing conditions. In the process, we confirmed that fluoxetine could improve the depression-like behaviors of PSD mice and upregulate the expression of BDNF in the hippocampus. However, depletion of BDNF by transfecting lentivirus-derived shBDNF in hippocampus suppressed the effect of fluoxetine. Furthermore, we demonstrated the epigenetic mechanisms involved in regulation of BDNF expression induced by fluoxetine. We found a statistically significant increase in DNA methylation at specific CpG sites (loci 2) of Bdnf promoter IV in the hippocampus of PSD mice. We also found that fluoxetine treatment could disassociate the MeCP2-CREB-Bdnf promoter IV complex via phosphorylation of MeCP2 at Ser421 by Protein Kinase A (PKA). Our research highlighted the importance of fluoxetine in regulating BDNF expression which could represent a potential strategy for preventing PSD.

Knockdown of SIRT1 Suppresses Bladder Cancer Cell Proliferation and Migration and Induces Cell Cycle Arrest and Antioxidant Response through FOXO3a-Mediated Pathways

Bladder cancer (BCa) is one of the most common tumors, but its underlying mechanism has not been fully clarified. Our transcriptome analysis suggested a close link of Sirtuins, Peroxisome Proliferator-Activated Receptor (PPAR), cell cycle regulation, reactive oxygen species (ROS) metabolism, and Forkhead Box Class O (FOXO) signaling pathway in BCa. SIRT1 is a key member of Sirtuins, playing important roles in aging and energy metabolism, which has been reported to be involved in various metabolic diseases and tumors. We observed that SIRT1 was upregulated in BCa tissues at both mRNA and protein levels. By establishing a SIRT1-knockdown BCa cell model, our results suggested that proliferation and viability were suppressed. Moreover, migration rate was inhibited as well, possibly via reduction of epithelial-mesenchymal transition (EMT). In addition, cell cycle arrest was significantly induced, consisting with strongly decreased proteins involved (CDK2/4/6). Furthermore, ROS production was slightly reduced, accompanied by increasing of antioxidant enzymes and total/acetylated FOXO3a. Consistently with our Path-net analysis, we observed no significant alteration of apoptosis in the SIRT1-knockdown BCa cells. Taken together, our results suggested that SIRT1 deficiency in BCa cells could suppress cell viability by activating antioxidant response and inducing cell cycle arrest possibly via FOXO3a-related pathways.

Changes in the expression level of MAPK pathway components induced by monosodium glutamate-administration produce neuronal death in the hippocampus from neonatal rats

Excessive Glutamate (Glu) release may trigger excitotoxic cellular death by the activation of intracellular signaling pathways that transduce extracellular signals to the cell nucleus, which determines the onset of a death program. One such signaling pathway is the mitogen-activated protein kinases (MAPK), which is involved in both survival and cell death. Experimental evidences from the use of specific inhibitors supports the participation of some MAPK pathway components in the excitotoxicity mechanism, but the complete process of this activation, which terminates in cell damage and death, is not clearly understood. The present work, we investigated the changes in the expression level of some MAPK-pathway components in hippocampal excitotoxic cell death in the neonatal rats using an experimental model of subcutaneous monosodium glutamate (MSG) administration on postnatal days (PD) 1, 3, 5 and 7. Data were collected at different ages through PD 14. Cell viability was evaluated using fluorescein diacetate mixed with propidium iodide (FDA-PI), and the Nissl-staining technique was used to evaluate histological damage. Transcriptional changes were also investigated in 98 components of the MAPK pathway that are associated with cell damage. These results are an evidence of that repetitive use of MSG, in neonatal rats, induces cell damage-associated transcriptional changes of MAPK components, that might reflect a differential stage of both biochemical and molecular brain maturation. This work also suggests that some of the proteins evaluated such as phosphorylated retinoblastoma (pRb) protein, which was up-regulated, could regulate the response to excitotoxic through modulation of the process of re-entry into the cell cycle in the hippocampus of rats treated with MSG.

Rosiglitazone Exerts an Anti-depressive Effect in Unpredictable Chronic Mild-Stress-Induced Depressive Mice by Maintaining Essential Neuron Autophagy and Inhibiting Excessive Astrocytic Apoptosis

There is increasing interest in the association between depression and the development of metabolic diseases. Rosiglitazone, a therapeutic drug used to treat type 2 diabetes mellitus, has shown neuroprotective effects in patients with stroke and Alzheimer's disease. The present study was performed to evaluate the possible roles of rosiglitazone in in vivo (unpredictable chronic mild stress-induced depressive mouse model) and in vitro (corticosterone-induced cellular model) depressive models. The results showed that rosiglitazone reversed depressive behaviors in mice, as indicated by the forced swimming test and open field test. Rosiglitazone was also found to inhibit the inflammatory response, decrease corticosterone levels, and promote astrocyte proliferation and neuronal axon plasticity in the prefrontal cortex of mice. This series of in vivo and in vitro experiments showed that autophagy among neurons was inhibited in depressive models and that rosiglitazone promoted autophagy by upregulating LKB1, which exerted neuroprotective effects. Rosiglitazone was also found to activate the Akt/CREB pathway by increasing IGF-1R expression and IGF-1 protein levels, thereby playing an anti-apoptotic role in astrocytes. Rosiglitazone's autophagy promotion and neuroprotective effects were found to be reversed by the PPARγ antagonist T0070907 in primary neurons and by PPARγ knockdown in an N2a cell line. In conclusion, we found that rosiglitazone protects both neurons and astrocytes in in vivo and in vitro depressive models, thereby playing an anti-depressive role. These findings suggest that PPARγ could be a new target in the development of anti-depressive drugs.

Novel Phosphodiesterase 4 Inhibitor FCPR03 Alleviates Lipopolysaccharide-Induced Neuroinflammation by Regulation of the cAMP/PKA/CREB Signaling Pathway and NF-κB Inhibition

Overactivation of microglia contributes to the induction of neuroinflammation, which is highly involved in the pathology of many neurodegenerative diseases. Phosphodiesterase 4 (PDE4) represents a promising therapeutic target for anti-inflammation; however, the dose-limiting side effects, such as nausea and emesis, have impeded their clinic application. FCPR03, a novel selective PDE4 inhibitor synthesized in our laboratory, shows little or no emetic potency; however, the anti-inflammatory activities of FCPR03 in vitro and in vivo and the molecular mechanisms are still not clearly understood. This study was undertaken to delineate the anti-inflammatory effects of FCPR03 both in vitro and in vivo and explore whether these effects are regulated by PDE4-mediated signaling pathway. BV-2 microglial cells stimulated by lipopolysaccharide (LPS) and mice injected i.p. with LPS were established as in vitro and in vivo models of inflammation. Our results showed that FCPR03 dose dependently suppressed the production of tumor necrosis factor α, interleukin-1β, and iinterleukin-6 in BV-2 microglial cells treated with LPS. The role of FCPR03 in the production of proinflammatory factors was reversed by pretreatment with protein kinase A (PKA) inhibitor H89. In addition, FCPR03 reduced the levels of proinflammatory factors in the hippocampus and cortex of mice injected with LPS. Our results further demonstrated that FCPR03 effectively increased the production of cAMP, promoted cAMP response element binding protein (CREB) phosphorylation, and inhibited nuclear factor κB (NF-κB) activation both in vitro and in vivo. Our findings suggest that FCPR03 inhibits the neuroinflammatory response through the activation of cAMP/PKA/CREB signaling pathway and NF-κB inhibition.

[Role of cAMP/CREB/BDNF signaling pathway in anti-depressive effect of vortioxetine in mice]

OBJECTIVE

To investigate the effects of vortioxetine on cAMP/CREB/BDNF signal pathway.

METHODS

Forty Kunming mice were randomized into control group and chronic unpredictable mild stress (CUMS) group. After establishment of depressive models verified by sucrose preference test, the mice in CUMS group were divided into model group, fluoxetine group and vortioxetine group. The antidepressive effect of vortioxetine was analyzed by tail suspension test, forced swim test and open field test. The levels of cAMP were detected using a commercial ELISA kit, and the expressions of pCREB and brain-derived neurotrophic factor (BDNF) were evaluated with Western blotting.

RESULTS

Vortioxetine significantly shortened the immobility time of the depressive mice in tail suspension test and forced swim test without affecting the locomotor activity of the mice in open fields, suggesting the antidepressive effect of against depression in mice. Vortioxetine significantly increased the levels of cAMP and promoted the expression of pCREB and BDNF in the hippocampus of the mice (P<0.01).

CONCLUSION

Vortioxetine improves the behaviors of mice with depression possibly by affecting the cAMP/CREB/BDNF signal pathway.

Discovery of 1,3-diyne compounds as novel and potent antidepressant agents: synthesis, cell-based assay and behavioral studies

1,3-Diynes compound 7a protected the corticosterone-injured PC12 cells through regulation of the apoptosis related proteins and exerted antidepressant effect in mice forced swim test in a concentration-dependent manner.

Capsaicin Suppresses Cell Proliferation, Induces Cell Cycle Arrest and ROS Production in Bladder Cancer Cells through FOXO3a-Mediated Pathways

Capsaicin (CAP), a highly selective agonist for transient receptor potential vanilloid type 1 (TRPV1), has been widely reported to exhibit anti-oxidant, anti-inflammation and anticancer activities. Currently, several therapeutic approaches for bladder cancer (BCa) are available, but accompanied by unfavorable outcomes. Previous studies reported a potential clinical effect of CAP to prevent BCa tumorigenesis. However, its underlying molecular mechanism still remains unknown. Our transcriptome analysis suggested a close link among calcium signaling pathway, cell cycle regulation, ROS metabolism and FOXO signaling pathway in BCa. In this study, several experiments were performed to investigate the effects of CAP on BCa cells (5637 and T24) and NOD/SCID mice. Our results showed that CAP could suppress BCa tumorigenesis by inhibiting its proliferation both in vitro and in vivo. Moreover, CAP induced cell cycle arrest at G0/G1 phase and ROS production. Importantly, our studies revealed a strong increase of FOXO3a after treatment with CAP. Furthermore, we observed no significant alteration of apoptosis by CAP, whereas Catalase and SOD2 were considerably upregulated, which could clear ROS and protect against cell death. Thus, our results suggested that CAP could inhibit viability and tumorigenesis of BCa possibly via FOXO3a-mediated pathways.