Antidepressant-like effects of Xiaochaihutang in a rat model of chronic unpredictable mild stress

Exploration of the mechanism of Traditional Chinese Medicine for anxiety and depression in patients with diarrheal irritable bowel syndrome based on network pharmacology and meta-analysis

Background

The efficacy of Chinese herbal medicine (CHM) in managing irritable bowel syndrome with diarrhea (IBS-D) accompanied by anxiety and depression remains uncertain. Thus, a systematic review was carried out employing meta-analysis and network pharmacology to ascertain the efficacy and underlying mechanisms of CHM therapy.

Methods

By conducting a systematic review, including literature search, screening, and data extraction, we identified 25 randomized controlled trials to assess CHM's effectiveness in treating irritable bowel syndrome alongside anxiety and depression. Network pharmacology was utilized to scrutinize the metabolite utility of CHM in addressing this condition. Potential primary mechanisms were synthesized using information sourced from the PubMed database.

Results

Twenty-five studies, including 2055 patients, were analyzed, revealing significant treatment efficacy for IBS-D in the trial group compared to controls [OR = 4.01, 95% CI (2.99, 5.36), I2 = 0%] Additionally, treatment for depression [SMD = -1.08, 95% CI (-1.30, -0.86), p < 0.00001, I2 = 68%; SDS: SMD = -1.69, 95% CI (-2.48, -0.90), p < 0.0001, I2 = 96%] and anxiety [HAMA: SMD = -1.29, 95% CI (-1.68, -0.91), p < 0.00001, I2 = 89%; SAS: SMD = -1.75, 95% CI (-2.55, -0.95), p < 0.00001, I2 = 96%] significantly improved in the trial group. Furthermore, the trial group exhibited a significantly lower disease relapse rate [OR = 0.30, 95% CI (0.20, 0.44), p < 0.00001, I2 = 0%]. CHM treatment consistently improved IBS severity (IBS-SSS) and symptom scores. Network pharmacology analysis identified key chemical metabolites in traditional Chinese medicine formulations, including Beta-sitosterol, Stigmasterol, Quercetin, Naringenin, Luteolin, Kaempferol, Nobiletin, Wogonin, Formononetin, and Isorhamnetin. Utilizing the STRING database and Cytoscape v3.9.0 software, a protein-protein interaction (PPI) network revealed the top eight key targets: IL-6, TNF, PPARG, PTGS2, ESR1, NOS3, MAPK8, and AKT1, implicated in anti-inflammatory responses, antioxidant stress modulation, and neurotransmitter homeostasis maintenance.

Conclusion

Chinese Herbal Medicine (CHM) offers a promising and safe treatment approach for patients dealing with Diarrheal Irritable Bowel Syndrome (IBS-D) accompanied by anxiety and depression; thus, indicating its potential for practical implementation. The most active metabolites of CHM could simultaneously act on the pathological targets of IBS-D, anxiety, and depression.The diverse scope of CHM's therapeutic role includes various aspects and objectives, underscoring its potential for broad utilization.

Influence of short-term hypoxic exposure on spatial learning and memory function and brain-derived neurotrophic factor in rats-A practical implication to human's lost way

The present study aimed to investigate the effects of a short period of normobaric hypoxic exposure on spatial learning and memory, and brain-derived neurotrophic factor (BDNF) levels in the rat hippocampus. Hypoxic conditions were set at 12.5% O2. We compared all variables between normoxic trials (Norm), after 24 h (Hypo-24 h), and after 72 h of hypoxic exposure (Hypo-72 h). Spatial learning and memory were evaluated by using a water-finding task in an open field. Time to find water drinking fountains was significantly extended in Hypo 24 h (36.2 ± 21.9 s) compared to those in Norm (17.9 ± 12.8 s; P < 0.05), whereas no statistical differences between Norm and Hypo-72 h (22.7 ± 12.3 s). Moreover, hippocampal BDNF level in Hypo-24 h was significantly lower compared to Norm (189.4 ± 28.4 vs. 224.9 ± 47.7 ng/g wet tissue, P < 0.05), whereas no statistically differences in those between Norm and Hypo-72 h (228.1 ± 39.8 ng/g wet tissue). No significant differences in the changes in corticosterone and adrenocorticotropic hormone levels were observed across the three conditions. When data from Hypo-24 h and Hypo-72 h of hypoxia were pooled, there was a marginal negative relationship between the time to find drinking fountains and BDNF (P < 0.1), and was a significant negative relationship between the locomotor activities and BDNF (P < 0.05). These results suggest that acute hypoxic exposure (24 h) may impair spatial learning and memory; however, it recovered after 72 h of hypoxic exposure. These changes in spatial learning and memory may be associated with changes in the hippocampal BDNF levels in rats.

Widely targeted metabolomics unveils baicalin-induced hippocampal metabolic alternations in a rat model of chronic unpredictable mild stress

Baicalin has various neuroprotective effects in models of nervous system disease. Our study has shown baicalin could alleviate depressive-like behaviors in a neuroendocrine mouse model. But the systematic metabolic characteristic and particular targets of baicalin in regulating depressive behaviors have never been investigated. Therefore, this study aims to reveal the hippocampal metabolic profiling of chronic unpredictable mild stress (CUMS) induced depressive rats and the potential metabolic variations after baicalin treatment. We first used the sucrose preference test and open field test to access the antidepressant effects of baicalin. Then, metabolites of the hippocampus after baicalin therapy were monitored by widely-targeted metabolomics based on ultra-performance liquid chromatography-tandem mass spectrometry technology. Finally, the potential mechanism associated with neurogenesis obtained from metabolomics was verified by immunohistochemistry. The results showed that baicalin(40,80 mg/kg) could significantly alleviate depressive behaviors induced by CUMS as demonstrated by an increase in sucrose preference and movement distance and stand-up times in open field test. In the metabolomic analysis, a total of 733 metabolites were identified after baicalin treatment including 15 differential metabolites such as organic acid and its derivatives, heterocyclic compounds, fatty acid, bile acids, amino acid and its metabolites, and so on. Enrichment for differential metabolites showed that the differential metabolites might be involved in the process of folate and cofactor biosynthesis, cholesterol metabolism, primary bile acid biosynthesis, tyrosine metabolism and dopaminergic synapse. Moreover, immunohistochemical analysis confirmed baicalin could facilitate hippocampal neurogenesis of depressive rats in CUMS model. These results suggested baicalin might exert antidepressant effects through regulating the differential metabolites which might play a crucial role in inhibiting oxidative stress and improving neurogenesis. Our findings wish to discover the potential mechanism of baicalin on depression from the metabolomics perspective and promote its clinical application.

Integration of metabolomics and network pharmacology to reveal the protective mechanism underlying Wogonoside in acute myocardial ischemia rats

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional medicine, both Scutellaria baicalensis Georgi (SBG) and the traditional formulas composed of it have been used to treat a wide range of diseases, including cancer and cardiovascular. Wogonoside (Wog) is the biologically active flavonoid compound extracted from the root of SBG, with potential cardiovascular protective effects. However, the mechanisms underlying the protective effect of Wog on acute myocardial ischemia (AMI) have not yet been clearly elucidated.

AIM OF THE STUDY

To explore the protective mechanism of Wog on AMI rats by comprehensively integrating traditional pharmacodynamics, metabolomics, and network pharmacology.

METHODS

The rat was pretreatment with Wog at a dose of 20 mg/kg/d and 40 mg/kg/d once daily for 10 days and then ligated the left anterior descending coronary artery of rats to establish the AMI rat model. Electrocardiogram (ECG), cardiac enzyme levels, heart weight index (HWI), Triphenyltetrazolium chloride (TTC) staining, and histopathological analyses were adopted to evaluate the protective effect of Wog on AMI rats. Moreover, a serum metabolomic-based UHPLC-Q-Orbitrap MS approach was performed to find metabolic biomarkers and metabolic pathways, and network pharmacology analysis was applied to predict targets and pathways of Wog in treating AMI. Then, the network pharmacology and metabolomic results were integrated to elucidate the mechanism of Wog in treating AMI. Finally, RT- PCR was used to detect the mRNA expression levels of PTGS1, PTGS2, ALOX5, and ALOX15 to validate the result of integrated metabolomics and network analysis.

RESULTS

Pharmacodynamic studies suggest that Wog could effectively prevent the ST-segment of electrocardiogram elevation, reduce the myocardial infarct size, heart weight index, and cardiac enzyme levels, and alleviate cardiac histological damage in AMI rats. Metabolomics analysis showed that the disturbances of metabolic profile in AMI rats were partly corrected by Wog and the cardio-protection effects on AMI rats involved 32 differential metabolic biomarkers and 4 metabolic pathways. In addition, the integrated analysis of network pharmacology and metabolomics showed that 7 metabolic biomarkers, 6 targets, and 6 crucial pathways were the main mechanism for the therapeutic application of Wog for AMI. Moreover, the results of RT-PCR showed that PTGS1, PTGS2, ALOX5, and ALOX15 mRNA expression levels were reduced after treatment with Wog.

CONCLUSION

Wog exerts cardio-protection effects on AMI rats via the regulation of multiple metabolic biomarkers, multiple targets, and multiple pathways, our current study will provide strong scientific evidence supporting the therapeutic application of Wog for AMI.

Antidepressant-like Effect of Oroxylum indicum Seed Extract in Mice Model of Unpredictable Chronic Mild Stress

Major depressive disorder (MDD) is one life-threatening disorder that is prevalent worldwide. The evident etiology of this disease is still poorly understood. Currently, herbal medicine is gaining more interest as an alternative antidepressant. Oroxylum indicum, which is used in traditional medicine and contains a potential antidepressive compound, baicalein, could have an antidepressive property. An in vitro monoamine oxidase-A (MAO-A) inhibitory assay was used to preliminarily screening for the antidepressant effect of O. indicum seed (OIS) extract. Mice were subjected to unpredictable chronic mild stress (UCMS) for 6 weeks, and the daily administration of OIS extract started from week 4. The mechanisms involved in the antidepressive activity were investigated. The OIS extract significantly alleviated anhedonia and despair behaviors in the UCMS-induced mouse model via two possible pathways: (i) it normalized the HPA axis function via the restoration of negative feedback (decreased FKBP5 and increased GR expressions) and the reduction in the glucocorticoid-related negative gene (SGK-1), and (ii) it improved neurogenesis via the escalation of BDNF and CREB expressions in the hippocampus and the frontal cortex. In addition, an HPLC analysis of the OIS extract showed the presence of baicalin, baicalein, and chrysin as major constituents. All of the results obtained from this study emphasize the potential of OIS extract containing baicalin and baicalein as an effective and novel alternative treatment for MDD.

Research on Xiaoyao Powder in the treatment of depression based on epigenetics and quality markers

Depression has become one of the most common public health issues around the world, and the incidence has been increasing in recent years. A large amount of clinical investigations have proven that the treatment of depression is difficult. The prognosis is poor, and the fatality rate is high. At present, western medicine is the preferred treatment for depression, but it often causes adverse clinical reactions such as dry mouth, blurred vision, and memory loss, etc. The herbal compound Xiaoyao Powder is a traditional medicine for soothing the liver and relieving depression, strengthening the spleen, and nourishing the blood. It can reduce adverse reactions. It is effective in treating depression. In this study, we elucidate the function of Xiaoyao Powder in anti-depression from the perspective of clinical application and pharmacological mechanisms such as regulating epigenetic and chemical quality markers to provide empirical and experimental theoretical results that contribute to developing future depression therapy with Xiaoyao Powder.

Scutellaria incarnata Vent. root extract and isolated phenylethanoid glycosides are neuroprotective against C2-ceramide toxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Neuronal death is a central process in neurodegenerative diseases and represents a therapeutic challenge for their prevention and treatment. Scutellaria incarnata Vent. roots are used traditionally in Colombia for central nervous system conditions including those affecting cognitive functions, but their chemistry and neuroprotective action remain to be explored to understand the scientific basis for their medicinal uses. In this study, S. incarnata roots are investigated to assess whether they have neuroprotective effects that could provide some explanation for their traditional use in neurodegenerative diseases.

AIM OF THE STUDY

To evaluate the neuroprotective effect of S. incarnata roots and its chemical constituents against C₂-ceramide-induced cell death in Cath.-a-differentiated (CAD) cells.

MATERIALS AND METHODS

S. incarnata root ethanol extract was fractionated and compounds were isolated by column chromatography; their structures were elucidated by nuclear magnetic resonance spectroscopy, mass spectrometry and infrared spectroscopy. The cytotoxic and neuroprotective effects against C₂-ceramide of S. incarnata root extract, fractions and isolated compounds were assessed in CAD cells.

RESULTS

S. incarnata root extract and its n-butanol fraction were not cytotoxic but showed neuroprotective effects against C₂-ceramide toxicity in CAD cells. The phenylethanoid glycosides incarnatoside (isolated for the first time) and stachysoside C (12.5, 25 and 50 μg/mL) from S. incarnata roots also protected CAD cells against C₂-ceramide without inducing cytotoxic effects.

CONCLUSION

The observed neuroprotective effects of S. incarnata root extract and isolated phenylethanoid glycosides in CAD cells provide an ethnopharmacological basis for the traditional use of this species in Colombia for central nervous system disorders.

Baixiangdan capsule and Shuyu capsule regulate anger-out and anger-in, respectively: GB1–mediated GABA can regulate 5-HT levels in multiple brain regions

The identity of the mechanism by which the Baixiangdan capsule (BXD) and the Shuyu capsule (SY) control anger-out (AO) and anger-in (AI) in rodents is unclear. The current study clarified the intervention role of BXD and SY on AO and AI male rats. We further explored the differences between BXD and SY in the treatment of AO and AI rats. Social isolation combined with the resident-intruder paradigm was used to establish the anger-out and AI rats models. On this basis, GABA content in the dorsal raphe nucleus (DRN) and serotonin (5-HT) contents in these brain regions were detected using ELISA after various time courses (0, 1, 3, 5, and 7 days) treated with BXD and SY. Co-expression of 5-HT and GB1 in the DRN was detected. GB1-specific agonist baclofen and GB1-specific inhibitor CGP35348 were injected into the DRN. Changes in 5-HT levels in these brain regions were then detected. After treatment, rats in the BXD group exhibited lower aggressive behavior scores, longer latencies of aggression, lower total distances in the open field test, and a higher sucrose preference coefficient. Meanwhile, rats in the SY group exhibited higher aggressive behavior scores, shorter latencies of aggression, higher total distances in the open field test, and higher sucrose preference coefficients. With increasing medication duration, 5-HT levels in these brain regions were increased gradually, whereas GABA levels in the DRN were decreased gradually, and all recovered to normal levels by the 7th day. A large number of 5-HT-positive cells could be found in the immunofluorescence section in the DRN containing GABABR1 (GB1)-positive cells, indicating that 5-HT neurons in the DRN co-expressed with GB1. Furthermore, after the drug intervention, the 5-HT level in the DRN was elevated to a normal level, and the GB1 level in the DRN was decreased to a normal level. After the microinjection of baclofen into the DRN, the 5-HT contents in these brain regions were decreased. By contrast, the 5-HT contents were increased after injection with CGP35348. BXD and SY could effectively improve the abnormal behavior changes of AO and AI rats, and the optimal duration of action was 7 days. The improvement way is as follows: Decreased abnormal increase of GABA and GB1 in the DRN further mediated synaptic inhibition and increased 5-HT level in the DRN, leading to increased 5-HT levels in the PFC, hypothalamus, and hippocampus. Therefore, GB1-mediated GABA in the DRN could regulate 5-HT levels in these brain regions, which may be one of the ways by which BXD and SY treat AO and AI, respectively.

Chaihu-Guizhi-Ganjiang Decoction is more efficacious in treating irritable bowel syndrome than Dicetel according to metabolomics analysis

Background

Chaihu-Guizhi-Ganjiang Decoction (CGGD) is a traditional Chinese medicine (TCM) prescription used to treat viral influenza. There is evidence that CGGD can be used to treat irritable bowel syndrome (IBS) but the potential mechanism of action and metabolites produced upon CGGD treatment remains elusive.

Methods

Patients with IBS were treated with pinaverium bromide (Dicetel™) and then CGGD after a washout period of 1 week. Both treatments lasted for 30 days. The efficacy and changes of metabolites in plasma after the two treatments were compared. Plasma samples were acquired before and after each treatment, and untargeted metabolics analysis was performed.

Results

Efficacy was measured according to the Rome IV criteria and TCM theory. Our results indicated that CGGD showed significantly better efficacy than Dicetel in the treatment of IBS utilizing each criterion. CGGD exerted greater effects on plasma metabolism than Dicetel. Dicetel treatment led to increased tryptophan metabolism (increased levels of 5-Hydroxyindoleacetaldehyde) and increased protein metabolism (increased levels of L-arginine). CGGD treatment significantly (p < 0.05) increased carnitine metabolism, with elevated levels of L-carnitine and acylcarnitine in plasma. Such changes in these metabolites could exert effects against IBS by improving gastrointestinal motility and suppressing pain, depression, and inflammation.

Conclusions

CGGD appeared to be more efficacious than Dicetel for treating patients with IBS. The findings provide a sound support for the underlying biomolecular mechanism of CGGD in the prevention and treatment of IBS.

Antidepressant effects of cherry leaf decoction on a chronic unpredictable mild stress rat model based on the Glu/GABA-Gln metabolic loop

Cherry leaves (Prunus pseudocerasus Lindl. [Rosaceae]), a traditional Chinese herbal medicine, can regulate the factors closely related to depression including inflammatory cytokines, oxidative stress and blood glucose level. However, the antidepressant effects of cherry leaves and underlying neuromodulatory mechanisms remain relatively have not been elucidated explicitly. The present study investigated the antidepressant effects of cherry leaf decoction (CLD). The underlying neuromodulatory mechanism was explored by examining the glutamate (Glu)/γ-aminobutyric acid (GABA)-glutamine (Gln) metabolic loop. The chronic unpredictable mild stress (CUMS) rodent model was used in this study. The main flavonoids components of CLD were identified using high-performance liquid chromatography (HPLC). The antidepressant effects of CLD were assessed throughout behavioural tests including the bodyweight, sucrose preference test (SPT), forced swimming test (FPT) and tail suspension test (TST). Moreover, The baseline levels of serum adrenocorticotropic hormone (ACTH) and corticosterone (CORT) were quantified. The expression of proteins integrally involved in the Glu/GABA-Gln metabolic loop were observed and quantified by Western blotting, reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. This study found that CLD ameliorated depressive-like behaviours induced by CUMS. The increase of serum ACTH and CORT baseline levels induced by CUMS was also reversed after CLD intervention. Furthermore, CUMS reduced the expression of GAD65, GAD67, GLT-1, GS and GABA_A and increased NMDAR1 levels in the rat hippocampus, which was normalized by CLD treatment. The findings demonstrated that CLD could ameliorate the depression-like behaviours induced by CUMS, potentially through the inhibition of hypothalamic-pituitary-adrenal (HPA) axis hyperactivity and the regulation of Glu/GABA-Gln metabolic loop.

Modified Xiaochaihu Decoction Combined with Mirtazapine in the Treatment of Persistent Depression: A Pilot Randomized Controlled Trial

Background

Western drugs effectively manage persistent depressive disorder (PDD) but are associated with side effects.

Objective

To observe the efficacy and safety of modified Xiaochaihu Decoction combined with mirtazapine in treating PDD.

Methods

Patients with PDD were enrolled at the Naval General Hospital (06/2018-02/2019) and randomized to modified Xiaochaihu Decoction and modified Xiaochaihu Decoction with mirtazapine. The self-rating depression scale (SDS) and traditional Chinese medicine (TCM) scale were assessed at baseline and after 12 weeks. The overall clinical efficacy (primary outcome) and adverse reactions were observed.

Results

Sixty-four participants completed the trial in the combined and control groups (30 and 28), respectively. In controls, the total effective rate was 78.6%, compared with 96.7% in the combined group (P=0.035). The scores of the SDS and TCM syndrome scale in the two groups were lower after treatment (P < 0.001) but without difference between groups (P=0.077). The combined group showed higher improvement rates regarding insomnia (96.4% vs. 44.0%, P < 0.001), bitter taste (90.5% vs. 52.6%, P=0.007), languid (72.0% vs. 31.8%, P=0.006), and belching/anorexia (100% vs. 52.6%, P < 0.001). The combined group showed a higher frequency of adverse events (73.3% vs. 3.6%) (P < 0.001).

Conclusion

Modified Xiaochaihu Decoction combined with mirtazapine effectively treats PDD, and its curative effect is better than that of TCM alone. Trial Registration. This trial was registered with https://www.chictr.org.cn/index.aspx/ChiCTR2100048188.

A Herbal Mixture of Sesami Semen Nigrum and Longan Arillus Induces Neurite Outgrowth in Cultured Neurons and Shows Anti-Depression in Chronic Mild Stress-Induced Rats

Medicinal food homology is referring to a group of food itself being considered as herbal medicine without a boundary of usage. Under the guidance of this food/medicine principle, the current study aims to develop anti-depressant from this food/medicine catalog. The herbal mixture of Sesami Semen Nigrum and Longan Arillus was evaluated in cultured PC12 rat pheochromocytoma cells, rat primary cortical neurons, and in chronic mild stress (CMS)-induced depressive rat model. The combination of two ethanolic extracts of Sesami Semen Nigrum and Longan Arillus in 1 : 1 ratio mimicked the function of nerve growth factor (NGF) and synergistically induced neurite outgrowth of PC12 cells. Besides, the expression and phosphorylation of tropomyosin receptor kinase A (TrkA) of the cultured cells were also elevated. This neurotrophic activity of herbal mixture was further supported by the increased expressions of biomarkers for neurogenesis and synaptogenesis in cortical neurons. Moreover, the depressed rats were soothed by the intake of herbal mixture, showing improved performance in behavior tests, as well as reversed levels of neurotransmitters and neurotrophic factors. Our results provide a new way to make full use of the current food/medicine resources, as to accelerate the development of therapeutics for depression.

Beneficial effects of Dendrobium nobile Lindl. Alkaloids (DNLA) on anxiety and depression induced by chronic unpredictable stress in rats

Dendrobium nobile Lindl. alkaloid (DNLA) is effective against animal models of Alzheimer's disease. This study further examined its effect on anxiety and depression produced by chronic unpredictable stress (CUS). Rats were subjected to CUS for 42 days, followed by DNLA treatment (20 mg/kg/day, po) for 28 days. The behavioral tests, histopathology, neurotransmitters and RNA-Seq were examined. DNLA attenuated body weight loss and CUS-induced anxiety/depressive-like behaviors, as evidenced by the elevated-plus-maze test, open-field test and sucrose preference. DNLA alleviated neuronal damage and loss and increased Nissl bodies in the hippocampus CA2 region and cortex. DNLA decreased CUS-elevated 5-hydroxytryptamine, dopamine and monoamine oxidase and catechol-O-methyltransferase activities in the brain. DNLA attenuated HPA activation by decreasing adrenocorticotropic hormones and the expression of corticotropin-releasing hormone receptor-1, and increased the expression of glucocorticoid receptor in the brain. RNA-Seq revealed distinct gene expression patterns among groups. Gene ontology revealed the cell projection assembly, postsynapse and centrosome as top biological processes, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment showed the cAMP, cGMP-PKG, glutamatergic synapse and circadian as major pathways for DNLA effects. Using DESeq2, CUS modulated 1700 differentially expressed genes (DEGs), which were prevented or attenuated by DNLA. CUS-induced DEGs were highly correlated with the Gene Expression Omnibus (GEO) database for anxiety and depression and were ameliorated by DNLA. Taken together, DNLA attenuated anxiety/depression-like behavior and neuronal damage induced by CUS in rats. The mechanisms could be related to regulation of the monoamine neurotransmitters and the HPA axis, and modulation of gene expression in the hippocampus.

5-HT Receptors and the Development of New Antidepressants

Serotonin modulates several physiological and cognitive pathways throughout the human body that affect emotions, memory, sleep, and thermal regulation. The complex nature of the serotonergic system and interactions with other neurochemical systems indicate that the development of depression may be mediated by various pathomechanisms, the common denominator of which is undoubtedly the disturbed transmission in central 5-HT synapses. Therefore, the deliberate pharmacological modulation of serotonergic transmission in the brain seems to be one of the most appropriate strategies for the search for new antidepressants. As discussed in this review, the serotonergic system offers great potential for the development of new antidepressant therapies based on the combination of SERT inhibition with different pharmacological activity towards the 5-HT system. The aim of this article is to summarize the search for new antidepressants in recent years, focusing primarily on the possibility of benefiting from interactions with various 5-HT receptors in the pharmacotherapy of depression.

Natural Products for Neurodegeneration: Regulating Neurotrophic Signals

Neurodegenerative disorders (NDs) are heterogeneous groups of ailments typically characterized by progressive damage of the nervous system. Several drugs are used to treat NDs but they have only symptomatic benefits with various side effects. Numerous researches have been performed to prove the advantages of phytochemicals for the treatment of NDs. Furthermore, phytochemicals such as polyphenols might play a pivotal role in rescue from neurodegeneration due to their various effects as anti-inflammatory, antioxidative, and antiamyloidogenic agents by controlling apoptotic factors, neurotrophic factors (NTFs), free radical scavenging system, and mitochondrial stress. On the other hand, neurotrophins (NTs) including nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT4/5, and NT3 might have a crucial neuroprotective role, and their diminution triggers the development of the NDs. Polyphenols can interfere directly with intracellular signaling molecules to alter brain activity. Several natural products also improve the biosynthesis of endogenous genes encoding antiapoptotic Bcl-2 as well as NTFs such as glial cell and brain-derived NTFs. Various epidemiological studies have demonstrated that the initiation of these genes could play an essential role in the neuroprotective function of dietary compounds. Hence, targeting NTs might represent a promising approach for the management of NDs. In this review, we focus on the natural product-mediated neurotrophic signal-modulating cascades, which are involved in the neuroprotective effects.

Baicalin promotes hippocampal neurogenesis via the Wnt/β-catenin pathway in a chronic unpredictable mild stress-induced mouse model of depression

Hippocampal neurogenesis is known to be related to depressive symptoms. Increasing evidence indicates that Wnt/β-catenin signaling regulates multiple aspects of adult hippocampal neurogenesis. Baicalin is a major flavonoid compound with multiple pharmacological effects such as anti-inflammatory, anti-apoptotic, and neuroprotective effects. The current study aimed to explore the antidepressant effects of baicalin and its possible molecular mechanisms affecting hippocampal neurogenesis via the regulation of the Wnt/β-catenin signaling pathway. A chronic mild unpredictable stress (CUMS) model of depression was used in the study. The CUMS-induced mice were treated with baicalin (50 and 100 mg/kg) for 21 days, orally, and the fluoxetine was used as positive control drug. The results indicated that baicalin alleviated CUMS-induced depression-like behaviour, and improved the nerve cells' survival of the hippocampal dentate gyrus (DG) in CUMS-induced depression of model mice and increased Ki-67- and doublecortin (DCX)-positive cells to restore CUMS-induced suppression of hippocampal neurogenesis. The related proteins in the Wnt/β-catenin signaling pathway, which declined in the CUMS-induced depression model of mice, were upregulated after baicalin treatment, including Wingless3a (Wnt3a), dishevelled2 (DVL2), and β-catenin. Further study found that the phosphorylation rate of glycogen synthase kinase-3β (GSK3β) and β-catenin nuclear translocation increased, as the levels of the β-catenin target genes cyclinD1, c-myc, NeuroD1, and Ngn2 upregulated after baicalin treatment. In conclusion, these findings suggest that baicalin may promote hippocampal neurogenesis, thereby exerting the antidepressant effect via regulation of the Wnt/β-catenin signaling pathway.

Korean traditional herbal formula Soshiho-tang attenuates memory impairment and neuronal damage in mice with amyloid-beta-induced Alzheimer's disease

Background

Soshiho-tang (SST), also known as Xiaochaihu-tang in China and Sho-saiko-to in Japan, is an Oriental herbal formula traditionally used to treat febrile diseases. Recently, several in vitro and in vivo studies have reported the anti-cancer, anti-liver disease, and anti-inflammatory activities of SST. However, there is little evidence of its effects on neurological diseases. We previously reported the inhibitory effects of SST on in vitro acetylcholinesterase (AChE) activation and amyloid-β (Aβ) aggregation, which are crucial hallmarks of Alzheimer's disease (AD). In the present study, we report that SST has preventive effects on memory impairment and neuronal cell changes in an Aβ-induced AD-like mouse model.

Methods

Male mice underwent injection of Aβ aggregates and administered SST (500, 1,000, or 2,000 mg/kg/day) for 20 days. Behavioral tests (passive avoidance task [PAT] and Morris water maze [MWM] test) were conducted. Lastly, brain sections were obtained from sacrificed mice for quantitative analysis.

Results

Intracerebroventricular (ICV) injection of Aβ aggregates significantly decreased the latency time in the PAT and MWM test compared to normal control. In contrast, SST administration markedly reversed the latency caused by Aβ injection. Additionally, our data revealed that SST-mediated improvements in memory impairment are related to its neuroprotective and anti-neuroinflammatory effects. On histological analysis, SST treatment protected neuronal loss and damage as well as microglial activation, and ameliorated amount of Aβ in brain of mouse model of AD.

Conclusion

Our findings suggest that SST may be a promising candidate for the development of novel drugs for AD.

Radix Scutellariae Ameliorates Stress-Induced Depressive-Like Behaviors via Protecting Neurons through the TGFβ3-Smad2/3-Nedd9 Signaling Pathway

Chronic stress can impair hippocampal neurogenesis, increase neuronal apoptosis, and cause depressive-like behaviors. Our previous studies found that Radix Scutellariae (RS) can rescue the stress-induced neuronal injury, but the mechanism is not clear. Here, we continued to investigate the underlying antidepressant mechanisms of the RS extract. A 7-week chronic unpredictable mild stress (CUMS) procedure was used to establish a murine depression model. 0.75 g/kg or 1.5 g/kg RS was administered daily to the mice during the last 4 weeks. Depressive-like behaviors were evaluated by the sucrose preference test (SPT), forced swimming test (FST), open field test (OFT), and tail suspension test (TST). The neuroprotective effect of RS was evaluated with the expression of hippocampal neuron-related markers and apoptosis-associated proteins by Nissl staining, immunohistochemistry, and western blot. Transforming growth factor-β3 (TGFβ3) pathway-related proteins were detected by western blot. Results showed that RS could ameliorate depressive-like behaviors, increase the expression of the antiapoptotic protein B-cell lymphoma 2 (BCL-2), reduce the expression of the proapoptotic protein BCL-2-associated X (BAX), and increase the number of doublecortin- (DCX-), microtubule-associated protein 2- (MAP2-), and neuronal nucleus- (NeuN-) positive cells in the hippocampus. Moreover, RS could reverse the CUMS-induced decrease of TGFβ3 protein, promote the phosphorylation of SMAD2/3, and increase the expression of downstream NEDD9 protein. These results suggest that RS could exert antidepressant effects via protecting neurons. And the molecular mechanism might be related to the regulation of the TGFβ3-SMAD2/3-NEDD9 pathway.

Metabolomics analysis of the antidepressant prescription Danzhi Xiaoyao Powder in a rat model of Chronic Unpredictable Mild Stress (CUMS)

ETHNOPHARMACOLOGICAL RELEVANCE

Danzhi Xiaoyao Powder (DZXY) is a classical prescription, that has been extensively used in traditional Chinese medicine (TMC) to treat depression for many years. However, the mechanism of DZXY is still unclear.

AIM OF THE STUDY

The aim was to investigate the mechanism of the antidepressant effect of DZXY on a rat model of chronic unpredictable mild stress (CUMS).

MATERIALS AND METHODS

Forty male SD (Sprague-Dawley) rats with similar open field test (OFT) results were randomLy divided into a control group (n = 10) and an experimental group (n = 30). A depression model was established in the experimental group using the CUMS method. After the CUMS model was established successfully, the rats were randomLy divided into a depression model group and a DZXY group. The DZXY group was fed DZXY, while the depression model group and control group were given an equal amount of 0.5% sodium carboxymethyl cellulose suspension. Intragastric administration was performed once daily for 14 consecutive days. Animal weight, the sugar preference test, the open field test and the forced swimming test were used to evaluate the modeling effect and the antidepressant effect of DZXY. After the experiment, the plasma of rats was collected and the changes in plasma metabolites were analyzed by UPLC/Q-TOF-MS. The UPLC/Q-TOF-MS spectra data were evaluated by pattern recognition analysis to determine the changes in endogenous metabolites in the rat plasma samples.

RESULTS

The results of the behavioral investigation showed that the rat model of depression was successfully replicated and that DZXY had an antidepressant effect. Using the UPLC-MS/MS metabolomics platform, partial least squares (PLS) and orthogonal partial least squares (OPLS), metabolic profile models (R2 and Q2 ≥ 0.5) of rat plasma were successfully constructed. The model could distinguish among the control group, the depression model group and the DZXY group. Finally, 38 differential metabolites were identified in the plasma. According to KEGG (http://www.kegg.jp) pathway analysis, amino acid metabolism, lipid metabolism, purine metabolism, the prolactin signaling pathway and bile secretion were enriched and represented the main metabolic pathways influenced in the plasma.

CONCLUSIONS

This study successfully established a CUMS depression model. A total of 38 differential metabolites associated with depression were identified in the plasma of rats, 24 of which were modulated by DZXY. These results suggest that DZXY can improve excitability and play an antidepressant role by regulating phenylalanine metabolism, arachidonic acid metabolism, porphyrin metabolism, D-arginine and D-ornithine metabolism, steroid hormone biosynthesis, unsaturated fatty acid biosynthesis and steroid biosynthesis.

Effect of Xiaoyaosan on Colon Morphology and Intestinal Permeability in Rats With Chronic Unpredictable Mild Stress

Purpose

In our present study, a rat depression model induced by 6 weeks of chronic unpredictable mild stress (CUMS) was established, and we investigated how Xiaoyaosan affects the intestinal permeability of depressed rats and alterations in tight-junction proteins (TJs) involved in this process.

Methods

The rat depression model was established using CUMS for 6 consecutive weeks. A total of 40 healthy male Sprague-Dawley rats were randomly sorted into four groups: the control group, CUMS group, Xiaoyaosan group, and fluoxetine group. All groups, excluding the control group, were subjected to the 6-week CUMS program to generate the depression model. Body weight, food intake, and behaviors were observed during the modeling period. Histopathological alterations of colon tissue were evaluated by hematoxylin-eosin staining (H&E), and mucus-containing goblet cells were detected by periodic acid-Schiff (PAS) staining. The ultrastructural morphology of colonic mucosa was observed by transmission electron microscopy. Furthermore, immunohistochemistry (IHC) and quantitative reverse transcription polymerase chain reaction (qRT-PCR) were used to determine the expression of TJs. The concentrations of 5-hydroxytryptamine (5-HT) in the hypothalamus and colon were also assessed using enzyme-linked immunosorbent assay (ELISA).

Results

Treatment of depressed rats with Xiaoyaosan alleviated depression-like behaviors as demonstrated by increases in the total distance traveled, the number of entries into the central area in the open field test, the duration spent in the central area, and sucrose preference. Xiaoyaosan treatment also increased body weight gain and food intake in depressed rats. Moreover, Xiaoyaosan treatment effectively improved the colonic pathological and ultrastructural changes, upregulated the expression of ZO-1, occludin, and claudin-1 in the colon, and increased 5-HT levels in the hypothalamus and colonic mucosa.

Conclusions

Xiaoyaosan treatment attenuates depression-like behaviors caused by CUMS and ameliorates CUMS-induced abnormal intestinal permeability, which may be associated with the expression of TJs. These results suggest that Xiaoyaosan exerts an antidepressant effect that may be related to an improvement of intestinal barrier function via the brain-gut axis.

Trace elements differences in the depression sensitive and resilient rat models

The etiology and pathophysiology of depressive disorders remain unclear. Increasing evidences have demonstrated that trace elements such as zinc, magnesium, iron, calcium, selenium, manganese and chromium play vital roles in depressive symptoms. We used a Chronic Unpredictable Mild Stress (CUMS) model to simulate social pressure in rat model and compared the levels of trace elements in the plasma and brain. The concentrations trace elements were evaluated using inductively coupled plasma mass spectrometry or inductively coupled plasma-atomic emission spectrometry. In the CUMS model, 57% (12/21) of rats showed no significant decrease in sucrose preference and were grouped as CUMS-resilient; otherwise, CUMS-sensitive. The resilient group had higher levels of iron, sodium, sulfur, manganese and cobalt than the sensitive group in the brain samples (P < 0.05). The sensitive group had lower levels of calcium, potassium, sulfur, selenium and cobalt than the resilient groups, in the plasma samples. The higher levels of iron, calcium, selenium, manganese and cobalt in the resilient group indicated these trace elements might be protective against the development of depressive symptoms in response to stress.

Dietary Flavonoids Interaction with CREB-BDNF Pathway: An Unconventional Approach for Comprehensive Management of Epilepsy

cAMP response element binding protein (CREB) is a key transcriptional regulator that regulates the transcription of genes related with neuronal differentiation, synaptic plasticity, learning and memory. Brain derived neurotrophic factor (BDNF), is a CREB dependent gene which plays a pivotal role in the pathogenesis of epilepsy and central comorbid conditions associated with epilepsy. However, the beneficial or detrimental consequences of CREB-BDNF activation on the induction and/or progression of seizures depend specifically on the region of brain involved and the time of activation. The bioactive molecules that alter the activity of CREB in a way to have specialized effects in different brain regions and neural circuits involved could potentially be utilized for therapeutic purposes. Flavonoids are the polyphenolic compounds which lead to phosphorylation of CREB in the hippocampus, followed by increase in extracellular signal regulated kinase (ERK) and BDNF. Several members of flavonoid family have also showed suppression of epileptic seizures via interaction with CREB/BDNF pathway. Moreover, epilepsy is often accompanied by a number of behavioural and psychological comorbid conditions that further gets aggravated by the use of conventional antiepileptic drug therapy. Multiple studies have also supported the beneficial effects of flavonoids in cognitive and memory impairments by upregulation of CREB-BDNF pathway. The current review is an attempt to collate the available preclinical and clinical studies to establish the therapeutic potential of various dietary flavonoids in comprehensive management of epilepsy with relation to CREB-BDNF pathway.

Potential Antidepressant Effects of Scutellaria baicalensis, Hericium erinaceus and Rhodiola rosea

Recent studies focused on the pharmacology and feasibility of herbal compounds as a potential strategy to target a variety of human diseases ranging from metabolic to brain disorders. Accordingly, bioactive ingredients which are found within a variety of herbal compounds are reported to produce both neuroprotective and psychotropic activities which may help to combat mental disorders such as depression, anxiety, sleep disturbances and cognitive alterations. In the present manuscript, we focus on three herbs which appear effective in mitigating anxiety or depression with favourable risk-benefit profiles, namely Scutellaria baicalensis (S. baicalensis), Hericium erinaceus (H. erinaceus) and Rhodiola rosea (R. rosea). These three traditional folk medicinal herbs target the main biochemical events that are implicated in mental disorders, mimicking, to some extent, the mechanisms of action of conventional antidepressants and mood stabilizers with a wide margin of tolerability. In detail, they rescue alterations in neurotransmitter and neuro-endocrine systems, stimulate neurogenesis and the synthesis of neurotrophic factors, and they counteract oxidative stress, mitochondrial dysfunction and inflammation. Albeit the encouraging results that emerge from both experimental and clinical evidence, further studies are needed to confirm and better understand the mental-health promoting, and specifically, the antidepressant effects of these herbs.

Antidepressant-like effects of Xiaochaihutang in perimenopausal mice

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaochaihutang (XCHT) is a traditional Chinese medicine prescription for thousand years in China. Our previous researches show that XCHT has antidepressant-like effects in several depression models, but effect and mechanism of XCHT in perimenopausal depression are still vague.

AIM OF THE STUDY

To reveal the antidepressant-like effect and mechanism of XCHT in perimenopausal mice.

MATERIALS AND METHODS

Perimenopausal depression model is executed by ovariectomy combined with chronic unpredictable mild stress (OVX-CUMS). Tail suspension test (TST), forced swim test (FST), elevated plus-maze (EPM), novelty suppressed feeding (NSF) and locomotor activity are used to assess antidepressant-like effects of XCHT. The Level of estradiol (E₂), follicle-stimulating hormone (FSH), gonadotrophin releasing hormone (GnRH), corticosterone (CORT), adrenocorticotrophic hormone (ACTH) and corticotropin releasing hormone (CRH) are evaluated by ELISA. Antidepressant mechanisms of XCHT in OVX-CUMS mice are analyzed by 5-hydroxytryptamine (5-HT), tryptophan hydroxylase 2 (TPH2) and estrogen receptor α and β (ERα/β).

RESULTS

The results show that OVX-CUMS significantly increases the immobility time in TST and FST, increases latency to feed, decreases food consumption in NSF and both the time spend and number of entries in open arms in EPM. While, oral administration of XCHT can significantly normalize above depression-like behaviors in OVX-CUMS mice. Moreover, XCHT also remarkably normalized levels of 5-HT, 5-HIAA, E₂, GnRH, CORT, ACTH and CRH in OVX-CUMS mice. Finally, the expression of ERβ and TPH2 are decreased by OVX-CUMS in prefrontal cortex and hypothalamus, and XCHT can restore these decrease.

CONCLUSION

Current findings suggest XCHT can alleviate perimenopausal depression-like behaviors, restore 5-HT and hormones in OVX-CUMS mice, which may be related to normalizing the functions of HPA/HPO axis and enhancing expression of ERβ and TPH2 in prefrontal cortex and hypothalamus.

Mechanisms of Panax ginseng action as an antidepressant

OBJECTIVES

Panax ginseng, a well-known traditional Chinese medicine with multiple pharmacological activities, plays a crucial role in modulating mood disorders. Several recent studies have identified an underlying role of Panax ginseng in the prevention and treatment of depression. However, the cellular and molecular mechanisms remain unclear.

MATERIALS AND METHODS

In this review, we summarized the recent progress of antidepressant effects and underlying mechanisms of Panax ginseng and its representative herbal formulae.

RESULTS

The molecular and cellular mechanisms of Panax ginseng and its herbal formulae include modulating monoamine neurotransmitter system, upregulating the expression of neurotrophic factors, regulating the function of HPA axis, and anti-inflammatory action.

CONCLUSIONS

Therefore, this review may provide theoretical bases and clinical applications for the treatment of depression by Panax ginseng and its representative herbal formulae.

Altered fibrinolytic system in rat models of depression and patients with first-episode depression

Tissue plasminogen activator (tPA) is a serine protease involved in cleavage of neurotrophic factors. In addition, tPA and neuroserpin can also directly bind to low density lipoprotein receptor-related protein 1 (LRP1), promoting neurogenesis and neurite outgrowth. Given both the cleavage and non-cleavage actions of the fibrinolytic system are crucial in neurological functions, the present study, for the first time, systematically detected the changes of fibrinolytic system factors in rats exposed to chronic unpredictable mild stress (CUMS) or lipopolysaccharide (LPS) and patients with depression. In general, our data demonstrated that both CUMS and LPS reduced tPA but elevated plasminogen activator inhibitor-1 (PAI-1; SERPINE1) mRNA expression. Intriguingly, decreased expression of neuroserpin and LRP1 was also observed in rats exposed to CUMS or LPS. The down-regulated neuroserpin and LRP1 signaling were confirmed by western blotting and immunoflurence data. Likewise, elevated PAI-1 but a significant reduction of neuroserpin and LRP1 mRNA expression were observed in the peripheral blood mononuclear cells (PBMCs) of patients with first-episode depression, and the mRNA levels of PAI-1, neuroserpin and LRP1 were correlated with the Beck Depression inventory (BDI) scores, further strengthening the clinical significance and involvement of the fibrinolytic system in depression. Collectively, the present study demonstrated the alterations of fibrinolytic system in stressed and inflamed brain and in patients with first-episode depression, firstly showing that not only the cleavage actions, but also the non-cleavage actions of the system may play an essential role in the development of depression.

Quantitative proteomics reveal antidepressant potential protein targets of xiaochaihutang in corticosterone induced model of depression

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaochaihutang (XCHT), one of famous Chinese herbal prescription for treating Shaoyang symptom, has been used successfully in depressive disorders for many years. Our laboratory has demonstrated that XCHT remarkably alleviated various depressive behaviors induced by several depressive animal models, but previous studies only focused on one or several protein targets, lacked dynamic change and interrelation of proteins. Therefore, potential protein targets and mechanisms are required further systematic investigation.

AIM OF THE STUDY

To discover and assess the differentially expressed proteins (DEPs) of hippocampus after oral administration of XCHT in corticosterone (CORT) induced model of depression by using isobaric tags for relative and absolute quantification (iTRAQ) analysis.

MATERIALS AND METHODS

The antidepressant effects of XCHT were assessed by two behavioral despair models (forced swimming test and tail suspension test) in CORT induced model of depression. The DEPs of hippocampus after XCHT treatment were investigated by iTRAQ analysis. Potential protein targets and mechanisms were assessed by gene ontology (GO), Kyoto encyclopedia of gene and genomes (KEGG) and protein-protein interaction (PPI) network.

RESULTS

Our data demonstrated XCHT could significantly improve depressive behaviors. A total of 241 DEPs were identified after XCHT treatment, including 68 up regulation and 173 down regulation proteins. GO enrichment results indicated that XCHT mainly regulated intracellular structural proteins involved in cellular response to stress, transferase activity and steroid hormone. KEGG enrichment analysis showed that endocytosis might be the principal pathway of XCHT on depression. PPI analysis predicted cell division cycle and apoptosis regulator protein 1 (Ccar1) and Calretinin (Calb2) might play the central roles in XCHT's antidepressant network.

CONCLUSION

Our results indicate that XCHT plays the important roles in antidepressant action by restoring DEPs, which results in the dysregulation of hippocampal neurogenesis, neurotransmitter and steroid hormone. The current results wish to provide novel perspectives for revealing the potential protein targets of XCHT on depression.

Serotonin receptors in depression and anxiety: Insights from animal studies

Serotonin regulates many physiological processes including sleep, appetite, and mood. Thus, serotonergic system is an important target in the treatment of psychiatric disorders, such as major depression and anxiety. This natural neurotransmitter interacts with 7 families of its receptors (5-HT1-7), which cause a variety of pharmacological effects. Using genetically modified animals and selective or preferential agonists and antagonist, numerous studies demonstrated the involvement of almost all serotonin receptor subtypes in antidepressant- or anxiolytic-like effects. In this review, based on animal studies, we discuss the possible involvement of serotonin receptor subtypes in depression and anxiety.

Antidepressant-Like Effects of Cistanche tubulosa Extract on Chronic Unpredictable Stress Rats Through Restoration of Gut Microbiota Homeostasis

Growing evidence shows that neuropsychiatric disorders, such as depression, are linked with gut microbiome through the gut–brain axis. Cistanches Herba is well known for the treatment of “kidney-yang” deficiency in traditional Chinese medicine (TCM), and has been used for treatment of neurodegenerative diseases in recent years. In this study, chronic unpredictable stress (CUS)-induced depression model was established to explore the impact of Cistanche tubulosa extract (CTE) on behavioral tests, monoamine neurotransmitters and neurotrophic factors in hippocampus and colon, gut microbiota composition, and short-chain fatty acids (SCFAs) production. Moreover, correlation analysis was used to evaluate the functional relationship between altered gut microbiota, changed neurotransmitters and neurotrophins in hippocampus and colon, and disturbed concentration of SCFAs. CTE significantly improved depression-like behaviors in rats under CUS. Brain level of 5-hydroxytryptamine (5-HT) and brain-derived neurotrophic factor (BDNF) expression in CUS rats were restored by CTE. The relative abundance of gut microbiota and the concentrations of acetate and hexanoic acid could also be modulated by CTE treatment. We further showed that the application of CTE in CUS rats led to strong correlation among disrupted gut microbiota composition, hippocampus neurotransmitter levels, and production of neuroactive metabolite SCFAs. Altogether, these results identify CTE as a potential treatment for depressive symptoms by restoring homeostasis of gut microbiota for microbiota–gut–brain axis disorders, opening new avenues in the field of neuropsychopharmacology.

Single Administration of HBK-15-a Triple 5-HT1A, 5-HT7, and 5-HT3 Receptor Antagonist-Reverses Depressive-Like Behaviors in Mouse Model of Depression Induced by Corticosterone

Studies suggest that the blockade of 5-HT1A, 5-HT7, and 5-HT3 receptor may increase the speed of antidepressant response. 1-[(2,6-Dimethylphenoxy)ethoxyethyl]-4-(2-methoxyphenyl)piperazine hydrochloride (HBK-14) and 1-[(2-chloro-6-methylphenoxy)ethoxyethyl]-4-(2-methoxyphenyl)piperazine hydrochloride (HBK-15), dual 5-HT1A and 5-HT7 antagonists, showed significant antidepressant- and anxiolytic-like properties in our previous tests in rodents. In this study, we aimed to investigate their antidepressant potential using mouse model of corticosterone-induced depression. We chose sucrose preference test, forced swim test, and elevated plus maze to determine anhedonic-, antidepressant-, and anxiolytic-like activities. We also evaluated the influence of the active compound on brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels in the hippocampus. Moreover, for both compounds, we performed biofunctional (5-HT3 receptor) and pharmacokinetic studies. We found that HBK-14 and HBK-15 were potent 5-HT3 receptor antagonists. HBK-14 (2.5 mg/kg) and HBK-15 (1.25 mg/kg) after intravenous (i.v.) and intraperitoneal (i.p.) administration permeated the blood-brain barrier with brain/plasma ratio lower than 1. The bioavailability of studied compounds after i.p. administration was 15% for HBK-14 and 54% for HBK-15. Chronic administration of HBK-15 (1.25 mg/kg) and fluoxetine (10 mg/kg) protected corticosterone-treated mice from anhedonic-, depressive-, and anxiety-like behaviors, as well as decreases in BDNF and NGF levels in the hippocampus. HBK-14 (2.5 mg/kg) counteracted anxiety-like behaviors in corticosterone-treated mice. Single administration of HBK-15 (1.25 mg/kg) and ketamine (1 mg/kg) reversed depression-like behavior and regulated decreased BDNF level in the hippocampus in corticosterone-treated mice. Our results suggest that simultaneous blockade of serotonergic 5-HT1A, 5-HT7, and 5-HT3 receptors might accelerate antidepressant response.

Advances in the Preclinical Study of Some Flavonoids as Potential Antidepressant Agents

Flavonoids are phenolic compounds found commonly in plants that protect them against the negative effects of environmental insults. These secondary metabolites have been widely studied in preclinical research because of their biological effects, particularly as antioxidant agents. Diverse flavonoids have been studied to explore their potential therapeutic effects in the treatment of disorders of the central nervous system, including anxiety and depression. The present review discusses advances in the study of some flavonoids as potential antidepressant agents. We describe their behavioral, physiological, and neurochemical effects and the apparent mechanism of action of their preclinical antidepressant-like effects. Natural flavonoids produce antidepressant-like effects in validated behavioral models of depression. The mechanism of action of these effects includes the activation of serotonergic, dopaminergic, noradrenergic, and γ-aminobutyric acid-ergic neurotransmitter systems and an increase in the production of neural factors, including brain-derived neurotrophic factor and nerve growth factor. Additionally, alterations in the function of tropomyosin receptor kinase B and activity of the enzyme monoamine oxidase A have been reported. In conclusion, preclinical research supports the potential antidepressant effects of some natural flavonoids, which opens new possibilities of evaluating these substances to develop complementary therapeutic alternatives that could ameliorate symptoms of depressive disorders in humans.

Apocynum venetum Leaf Extract Exerts Antidepressant-Like Effects and Inhibits Hippocampal and Cortical Apoptosis of Rats Exposed to Chronic Unpredictable Mild Stress

We investigated the effects of Apocynum venetum leaf extract (AVLE) on depressive behaviors and neuronal apoptosis in a chronic unpredictable mild stress (CUMS) rat model of depression. Rats were randomly divided into six groups: control, chronic unpredictable mild stress, fluoxetine, AVLE30, AVLE60, and AVLE120. Except for the control group, all rats were submitted to chronic unpredictable mild stress paradigms for four weeks to induce depressive behavior. Neuronal apoptosis was assessed by the terminal deoxynucleotidyl transferase- (TDT-) mediated dUTP-biotin nick end-labeling (TUNEL) method. The expression levels of apoptosis-related proteins, such as B-cell lymphoma 2 (Bcl-2), Bcl-2 Associated X Protein (Bax), cysteine-aspartic acid protease-3 and protease-9 (caspase-3 and caspase-9), cytochrome c (cyt-C), brain-derived neurotrophic factor (BDNF), and cAMP-response element binding (CREB) protein, were evaluated by western blot. Treatment with AVLE (60 or 120 mg/kg/day) significantly improved depressive behavior. Increased apoptosis of hippocampus and cortical neurons were observed in CUMS rats, while 120 mg/kg/day of AVLE significantly reversed these changes and achieved the best antidepressant-like effects among the doses tested. Moreover, AVLE (120 mg/kg) significantly increased Bcl-2, BDNF, and CREB protein expression and decreased Bax, cyt-C, and caspase family protein expression. Our results indicate that AVLE has potent antidepressant activity, likely due to its ability to suppress neuronal apoptosis.

Neurotrophic function of phytochemicals for neuroprotection in aging and neurodegenerative disorders: modulation of intracellular signaling and gene expression

Bioactive compounds in food and beverages have been reported to promote health and prevent age-associated decline in cognitive, motor and sensory activities, and emotional function. Phytochemicals, a ubiquitous class of plant secondary metabolites, protect neuronal cells by interaction with cellular activities, in addition to the antioxidant and anti-inflammatory function. In aging and age-associated neurodegenerative disorders, phytochemicals protect neuronal cells by neurotrophic factor-mimic activity, in addition to suppression of apoptosis signaling in mitochondria. This review presents the cellular mechanisms underlying anti-apoptotic function and neurotrophic function of phytochemicals in the brain. Phytochemicals bind to receptors of neurotrophic factors, and also receptors for γ-aminobutyric acid, acetylcholine, serotonin, and glutamate and estrogen, and activate downstream signal pathways. Phytochemicals also directly intervene intracellular signaling molecules to modify the brain function. Finally, phytochemicals enhance the endogenous biosynthesis of genes coding anti-apoptotic Bcl-2 and neurotrophic factors, such as brain-derived and glial cell line-derived neurotrophic factor. The gene induction may play a major role in the neuroprotective function of dietary compounds shown by epidemiological studies. Quantitative measurement of neurotrophic factors induced by phytochemicals in the serum, cerebrospinal fluid, and other clinical samples is proposed as a surrogate assay method to evaluate the neuroprotective potency. Development of novel neuroprotective compounds is expected among compounds chemically synthesized from the brain-permeable basic structure of phytochemicals.

Neuroplasticity-related mechanisms underlying the antidepressant-like effects of traditional herbal medicines

Traditional herbal medicine can offer efficacious and safe alternative pharmacotherapies for depression. The ability of an herbal medicine to produce neuroadaptive processes, that enhance neuroplasticity and cellular resilience in response to chronic stress, may point to its antidepressant potential. We suggest that among many investigated herbal medicines, those that can enhance neuroplasticity may have stronger therapeutic potential. The current article presents a summary of traditional herbal medicines, which are thought to exert antidepressant-like effects in chronic stress models via neuroplasticity enhancement. Brain-derived neurotrophic factor (BDNF) is a biomarker for neuroplasticity-related mechanisms compromised in depression and recovered by conventional antidepressants, including synaptic plasticity, cell survival, neurogenesis and spine formation. We therefore presumed that if an herbal medicine up-regulates BDNF in the hippocampus and/or prefrontal cortex (PFC), its antidepressant-like effect is mediated, at least partially, via neuroplasticity-related mechanisms. Literature search was performed using the general terms depression, stress, neuroplasticity and herbal medicines. Screening of retrieved preclinical studies revealed 30 traditional herbal medicines: 8 single herbs, 15 bioactive constituents, and 7 herbal formulas. The antidepressant-like effects of these medicines were associated with reversal of chronic stress-induced impairment in neuroplasticity, most notably by BDNF up-regulation, activation of BDNF downstream signaling pathways and increase in neurogenesis in the hippocampus and/or PFC/frontal cortex. In light of the ability of these medicines to enhance neuroplasticity, we suggest that they may be suitable candidates for clinical investigation in depressed individuals. Once their efficacy, tolerability and safety will be substantiated, they may serve as natural alternatives to conventional antidepressants.

Xiaochaihutang attenuates depressive/anxiety-like behaviors of social isolation-reared mice by regulating monoaminergic system, neurogenesis and BDNF expression

ETHNOPHARMACOLOGICAL RELEVANCE

Xiaochaihutang (XCHT), as a classical herbal formula for the treatment of "Shaoyang syndrome" has been demonstrated to exert an antidepressant effect in multiple animal models of depression as shown in our previous studies. However, the effects of XCHT on social isolation (SI)-reared mice have not been investigated. This study aims to explore the effects of XCHT on depressive/anxiety-like behaviors of SI-reared mice, and its implicated mechanisms, including alterations in the monoaminergic system, neurogenesis and neurotrophin expression.

MATERIALS AND METHODS

Male C57 BL/6J mice (aged 4 weeks after weaning) were reared isolatedly for 8 weeks and XCHT (0.8, 2.3, 7.0g/kg) were given by gavage once a day. Forced swimming test (FST), tail suspension test (TST), open field test (OFT), elevated-plus maze test (EPM) and intruder-induced aggression test were used to explore the effects of XCHT on depressive/anxiety-like behaviors of SI-reared mice after administration of XCHT for 6 weeks. HPLC-MS/MS was performed to quantify the levels of neurotransmitters in the hippocampus by in vivo microdialysis, while western immunoblotting was used to evaluate the action of XCHT on the synthesis, transport and degradation of monoamine neurotransmitters. Immunofluorescence was used to study the effects of XCHT on neurogenesis and neurotrophin expression, including Ki-67, DCX, BrdU and BDNF.

RESULTS

Our results showed that administration of XCHT (0.8, 2.3 and 7.0g/kg) for 6 weeks significantly attenuated the increase in immobility time in TST and FST, improved the anxiety-like behaviors in OFT and EPM, and improved the aggressive behaviors of SI-reared mice. XCHT significantly elevated monoamine neurotransmitters levels and inhibited 5-HT turnover (5-HIAA/5-HT) in hippocampal microdialysates of SI-reared mice. In addition, we found XCHT enhanced monoamine neurotransmitter synthesis enzymes (TPH2 and TH) expressions, inhibited serotonin transporter (SERT) expression and decreased monoamine neurotransmitter degradation enzyme (MAO_A) expression in the hippocampus of SI-reared mice for the first time. Moreover, XCHT significantly augmented hippocampal neurogenesis and BDNF expression in hippocampus of SI-reared mice.

CONCLUSIONS

Our results showed for the first time that XCHT improved depressive/anxiety-like behaviors of SI-reared mice by regulating the monoaminergic system, neurogenesis and neurotrophin expression. The findings indicate that XCHT may have a therapeutic application for early-life stress model of depression and in turn provide further evidence supporting XCHT a novel potential antidepressant from a distinct perspective.

Identification of NF-κB as Determinant of Posttraumatic Stress Disorder and Its Inhibition by the Chinese Herbal Remedy Free and Easy Wanderer

Posttraumatic stress disorder (PTSD) is a mental disorder developing after exposure to traumatic events. Although psychotherapy reveals some therapeutic effectiveness, clinically sustainable cure is still uncertain. Some Chinese herbal formulae are reported to work well clinically against mental diseases in Asian countries, but the safety and their mode of action are still unclear. In this study, we investigated the mechanisms of Chinese remedy free and easy wanderer (FAEW) on PTSD. We used a reverse pharmacology approach combining clinical data to search for mechanisms of PTSD with subsequent in vitro verification and bioinformatics techniques as follows: (1) by analyzing microarray-based transcriptome-wide mRNA expression profiling of PTSD patients; (2) by investigating the effect of FAEW and the antidepressant control drug fluoxetine on the transcription factor NF-κB using reporter cell assays and western blotting; (3) by performing molecular docking and literature data mining based on phytochemical constituents of FAEW. The results suggest an involvement of inflammatory processes mediated through NF-κB in the progression of PTSD. FAEW was non-cytotoxic in vitro and inhibited NF-κB activity and p65 protein expression. FAEW's anti-inflammatory compounds, i.e., paeoniflorin, isoliquiritin, isoliquiritin apioside and ononin were evaluated for binding to IκK and p65-RelA in a molecular docking approach. Paeoniflorin, albiflorin, baicalin, isoliquiritin and liquiritin have been reported to relieve depression in vivo or in clinical trials, which might be the active ingredients for FAEW against PTSD.

Saikosaponin A Alleviates Symptoms of Attention Deficit Hyperactivity Disorder through Downregulation of DAT and Enhancing BDNF Expression in Spontaneous Hypertensive Rats

The disturbed dopamine availability and brain-derived neurotrophic factor (BDNF) expression are due in part to be associated with attention deficit hyperactivity disorder (ADHD). In this study, we investigated the therapeutical effect of saikosaponin a (SSa) isolated from Bupleurum Chinese DC, against spontaneously hypertensive rat (SHR) model of ADHD. Methylphenidate and SSa were orally administered for 3 weeks. Activity was assessed by open-field test and Morris water maze test. Dopamine (DA) and BDNF were determined in specific brain regions. The mRNA or protein expression of tyrosine hydroxylase (TH), dopamine transporter (DAT), and vesicles monoamine transporter (VMAT) was also studied. Both MPH and SSa reduced hyperactivity and improved the spatial learning memory deficit in SHRs. An increased DA concentration in the prefrontal cortex (PFC) and striatum was also observed after treating with the SSa. The increased DA concentration may partially be attributed to the decreased mRNA and protein expression of DAT in PFC while SSa exhibited no significant effects on the mRNA expression of TH and VMAT in PFC of SHRs. In addition, BDNF expression in SHRs was also increased after treating with SSa or MPH. The obtained result suggested that SSa may be a potential drug for treating ADHD.

Antidepressant-like effects of Xiaochaihutang in a neuroendocrine mouse model of anxiety/depression

ETHNOPHARMACOLOGICAL RELEVANCE

Hyperactivity of hypothalamic-pituitary-adrenal (HPA) axis is often observed in the pathophysiology of depression. Antidepressant therapy can restore hippocampal neurogenesis to rescue the HPA axis regulation defects. Xiaochaihutang (XCHT), a famous Chinese herbal formula, has been used clinically in depressive disorders in China. Our previous studies have demonstrated XCHT improved depressive-like behaviors in chronic unpredictable mild stress rat, but the underlying mechanisms of XCHT on hippocampal neurogenesis and the HPA axis were still unclear.

MATERIALS AND METHODS

We used chronic corticosterone (CORT)-induced mouse model of anxiety/depression to investigate antidepressant-like effects of XCHT by several physical and behavioral testing, including body weight, coat state, open field test, elevated plus maze, tail suspension test and forced swimming test. The integrity of negative feedback function on HPA axis was assessed by the dexamethasone (DEX) suppression test. In addition, Ki-67 and doublecortin (DCX) were performed to assess hippocampal cell proliferation and neurogenesis by immunohistochemistry. Chemical profile of active constituents in brain after oral administration of XCHT was revealed by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

RESULTS

Our results showed that oral administration of XCHT (2.3, 7 and 21g/kg) for 30 days remarkably normalized chronic CORT-induced the slowness in weight gain, the deterioration in coat state, the escape behavior in open field test and elevated plus maze, and the increase of immobility time in tail suspension test and forced swimming test. Moreover, XCHT significantly reversed chronic CORT-induced the reduction of DEX-induced plasma corticosterone/c-Fos suppression and Ki-67/DCX positive cells. Finally, a total 13 potential active constituents in brain were identified by UPLC-MS/MS after oral administration of XCHT, including 10 prototype components and 3 metabolites.

CONCLUSIONS

Our findings showed that XCHT could remarkably alleviate chronic CORT-induced anxiety/depression-like behaviors, which were probably attribute to promoting hippocampal neurogenesis and remodeling the integrity of the negative feedback loop on HPA axis. The constituents identified in brain might contribute to understanding the therapeutic basis of XCHT on depression.