Schisandra chinensis produces the antidepressant-like effects in repeated corticosterone-induced mice via the BDNF/TrkB/CREB signaling pathway

A Reverse Thinking Based on Partially Methylated Aldononitrile Acetates to Analyze Glycoside Linkages of Polysaccharides Using Liquid Chromatography-Multiple Reaction Monitoring Mass Spectrometry

Glycoside linkage analyses of medicine and food homologous plant polysaccharides have always been a key point and a difficulty of structural characterization. The gas chromatography-mass spectrometry (GC-MS) method is one of the commonly used traditional techniques to determine glycoside linkages via partially methylated alditol acetates and aldononitrile acetates (PMAAs and PMANs). Due to the simplicity of derivatization and the highly structural asymmetry of PMANs, reverse thinking is proposed using liquid chromatography-electrospray ionization-multiple reaction monitoring mass spectrometry (LC-ESI-MRM-MS) for the first time to directly determine the neutral and acidic glycosyl linkages of polysaccharides. The complete characterization of glycoside linkages deduced from PMANs was achieved using a combination of tR values, characteristic MRM ion pairs, diagnostic ESI+-MS/MS fragmentation ions (DFIs), and optimal collision energy (OCE). The DFI and OCE parameters were confirmed to be effective for the auxiliary discrimination of some isomers of the PMANs. The practicality of LC-ESI+-MRM-MS was further verified by analyzing the glycoside linkages of polysaccharides in five medicine and food homologous plants. This method can serve as an alternative to GC-MS for the simultaneous determination of neutral and acidic glycosyl linkages in polysaccharides.

Extraction, purification, structural characterization, and bioactivities of the genus Schisandra polysaccharides: A review

The genus Schisandra, a member of the Magnoliaceae family, is a well-known tonic traditional Chinese medicine with a long history of traditional medicinal and functional food used in China. Polysaccharides are one of its main active constituents, which have a wide range of bioactivities, such as anti-inflammatory, anti-tumor, neuroprotection, anti-diabetes, hepatoprotection, immunomodulation, and anti-fatigue. In this paper, we review the extraction, isolation, purification, structural characterization, bioactivities, as well as structure-activity relationship of polysaccharides from the genus Schisandra. In conclusion, we hope that this review could provide reference for the subsequent research on structural, bioactivities, development and application of the genus Schisandra polysaccharides.

The physicochemical characteristics and antidepressant-like effects of a polysaccharide-rich fraction from Schisandra chinensis (Turcz.) Baill in behavioral despair mice and olfactory bulbectomy-induced depression-like mice

ETHNOPHARMACOLOGICAL RELEVANCE

The dried fruit of Schisandra chinensis (Turcz.) Baill (S. chinensis) is widely used in treating central nervous system disorders. Increasing evidence has suggested that alcohol-soluble extracts and lignans from S. chinensis could significantly ameliorate depression-like behaviors in animal models, while there was little research on the potential of alcohol-insoluble polysaccharides as a candidate in the treatment of depression.

AIM OF THE STUDY

Our research was designed to explore both the physicochemical characteristics and antidepressant-like effects of an alcohol-insoluble polysaccharide-rich fraction named SCP from S. chinensis. Simultaneously, the underlying mechanisms were elucidated in the study.

MATERIALS AND METHODS

The physicochemical characteristics were accomplished by colorimetric assays, CE, HPGPC, and FT-IR. Behavioral despair testing accompanied by LAT were processed to promptly assess the antidepressant-like effects of SCP in mice. Then OBX-induced mice were established to explore the impacts of chronic co-treatments with SCP. Furthermore, effects of SCP on the HPA axis, oxidant/antioxidant system, neurotrophic and synaptic factors, and gut microbiota in OBX-induced mice were detected through ELISA and 16S rDNA (V3 + V4 regions) gene sequencing.

RESULTS

SCP is a polysaccharide-rich fraction mainly comprised of xylose, glucose, rhamnose, galactose, mannose, and galacturonic acid in ratios of 0.27, 5.09, 0.24, 1.00, 0.63, and 2.86, of which the MW distribution ranges from 681 to 3232 Da. Acute pre-treatment with SCP (200 mg/kg, i.g.) remarkably reduced mice's immobility in the FST without motor stimulation. Prolonged pre-treatments effectively enhanced the effects of SCP on the behavioral despair testing in mice. Chronic co-treatments with SCP (50, 200, and 800 mg/kg, i.g.) could ameliorate the slow increase of body weight and behavioral abnormality of OBX-induced mice in systemic behavioral testing. SCP (200 mg/kg) also successfully restored hyperactivity of the HPA axis, oxidative damage in the liver, neurotrophic disturbance and abnormal synaptic plasticity in the hippocampus, and dysregulation of gut microbiota in OBX-induced mice.

CONCLUSION

SCP exerts noteworthy antidepressant-like impacts on behavioral despair mice and OBX-induced mice via multiple targets, indicating a potential therapeutic candidate in depression therapy.

Exploring the mechanism of Icariin in the treatment of depression through BDNF-TrkB pathway based on network pharmacology

Depression has increasingly become a disease that seriously harms people's mental health around the world. Icariin is the main active component of Epimedii Herba and effective on protecting the central nervous system. The purpose of this study was to explore the mechanism of icariin against depression based on network pharmacology and molecular docking. The potential targets related to icariin and depression were obtained by accessing network databases. The Metascape database was used for the enrichment analysis of GO function and KEGG pathways. A common target-pathway network was constructed using Cytoscape 3.9.0 software. Schrödinger Maestro 12.8 was adopted to evaluate the binding ability of icariin to core targets. Mice were induced by the chronic unpredictable mild stress (CUMS) model, and the prediction results of this study were verified by in vivo experiments. A total of 109 and 3294 targets were identified in icariin and depression, respectively. The common target-pathway network was constructed, and 7 core target genes were obtained. The molecular docking results of the 7 core target genes with icariin showed good affinity. In a CUMS-induced depression model, we found that icariin could effectively improve depression-like behavior of mice, increase the expression of monoamine neurotransmitters 5-hydroxytryptamine, dopamine, and norepinephrine, decrease the secretion of inflammatory factors tumor necrosis factor-α, interleukin-6, and interleukin-1β, and upregulate the relative expression levels of BDNF, p-TrkB/TrkB, p-Akt/Akt, p-CREB/CREB, MAPK3, MAPK1, Bcl-2, EGFR, and mTOR. The results suggest that icariin has certain antidepressant effects, and may be mediated by the BDNF-TrkB signaling pathway. It provides new ideas for the treatment of depression in the future.

Bicyclol Attenuates Obesity-Induced Cardiomyopathy via Inhibiting NF-κB and MAPK Signaling Pathways

PURPOSE

Schisandra is a well-known traditional Chinese medicine in East Asia. As a traditional Chinese medicine derivative with Schisandra chinensis as raw material, bicyclol is well known for its significant anti-inflammatory effect. Chronic inflammation plays a significant part in obesity-induced cardiomyopathy. Our purpose was to explore the effect and mechanism of bicyclol on obesity-induced cardiomyopathy.

METHODS

Mice fed with a high-fat diet (HFD) and cardiomyocytes stimulated by palmitic acid (PA) were used as models of obesity-related cardiomyopathy in vivo and in vitro, respectively. The therapeutic effect of bicyclol on pathological changes such as myocardial hypertrophy and fibrosis was evaluated by staining cardiac tissue sections. PCR was used to detect inflammatory factors in H9c2 cells and animal heart tissue after bicyclol treatment. Then, we used western blotting to detect the expression levels of the myocardial hypertrophy related protein, myocardial fibrosis related protein, NF-κB and MAPK pathways.

RESULTS

Our results indicated that bicyclol treatment significantly alleviates HFD-induced myocardial inflammation, fibrosis, and hypertrophy by inhibiting the MAPK and NF-κB pathways. Similar to animal level results, bicyclol could significantly inhibit PA-induced inflammation and prevent NF-κB and MAPK pathways from being activated.

CONCLUSION

Our results showed that bicyclol has potential as a drug to treat obesity-induced cardiomyopathy.

Headspace stir-bar sorptive extraction combined with gas chromatography-mass spectrometry for trace analysis of volatile organic compounds in Schisandra chinensis Baillon (omija)

Analyzing volatile organic compounds (VOCs) in food is crucial but challenging. Schisandra chinensis Baillon (omija) is an herbal plant with various functional health activities. Previous VOC analyses focused on S. chinensis fruit but not its leaves. Therefore, VOCs in S. chinensis fruit and leaves were analyzed using headspace stir-bar sorptive extraction (HS-SBSE)-GC-MS, and optimal conditions were established. Various factors, such as the sample preparation method, twister stir-bar type, sample amount, extraction temperature, and extraction time, expected to affect extraction were carefully optimized. Under the optimal conditions, 35 and 40 VOCs were identified in S. chinensis fruit and leaves, respectively. This HS-SBSE method is capable of rapid analysis and a low contamination rate without requiring organic solvents. These findings provide practical guidelines for HS-SBSE applications in various food matrices by providing analytical methods for VOC detection.

The study of therapeutic efficacy and mechanisms of Schisandra chinensis and Evodia rutaecarpa combined treatment in a rat model of Alzheimer's disease

Schisandra chinensis and Evodia rutaecarpa are traditional Chinese herbs used to treat neurodegenerative diseases. This study investigates the combined effects of SC and ER on learning and memory in an Alzheimer's disease rat model and their underlying mechanisms.

Methods

High-performance liquid chromatography was employed to analyze the primary active constituents of Schisandra and Evodia. The effects of the combined treatment of Schisandra and Evodia on learning and memory in an Alzheimer's disease rat model were evaluated through Morris water maze and Hematoxylin-Eosin staining experiments. Immunohistochemical analysis was conducted to investigate the impact of S-E on Aβ1-42 and P-tau proteins. Western blotting and real-time quantitative polymerase chain reaction were utilized to quantify the expression of pivotal proteins and genes within the BDNF/TRKB/CREB and GSK-3β/Tau pathways.

Results

The treatment group exhibited significant neuroprotective effects, ameliorating learning and memory impairments in the Alzheimer's disease rat model. The treatment regimen modulated the activity of the BDNF/TRKB/CREB and GSK-3β/Tau pathways by influencing the expression of relevant genes, thereby reducing the generation of Aβ1-42 and P-Tau proteins and inhibiting the deposition of senile plaques. Furthermore, among the three treatment groups, the combined treatment demonstrated notably superior therapeutic effects on Alzheimer's disease compared to the single-drug treatment groups.

Electroacupuncture ameliorates pain in cervical spondylotic radiculopathy rat by inhibiting the CaMKII/CREB/BDNF signaling pathway and regulating spinal synaptic plasticity

BACKGROUND

Central sensitization is one of the important mechanisms underlying neuropathic and radicular pain due to cervical spondylotic radiculopathy (CSR). Recent studies have shown that the calmodulin-dependent protein kinase II (CaMKII)/cAMP-response element binding protein (CREB)/brain-derived neurotrophic factor (BDNF) signaling pathway mediates central sensitization through its involvement in spinal cord synaptic plasticity. Our group has previously found that electroacupuncture (EA) has a good analgesic effect on CSR. However, the central analgesic mechanism of EA for CSR is not yet clear.

METHODS

The rats were randomly divided into Blank group, Sham-operated group, CSR group, and EA group. We prepared the CSR rat model using the fish wire extrusion method. The behavioral and mechanical pain thresholds of the rats in each group were measured 5 days after successful modeling and 7 days after the intervention. The first intervention was started 5 days after successful modeling, and the EA group was treated by acupuncture at the bilateral LI4 and LR3 points on the same side as one group, connected to a G6805-I electroacupuncture apparatus with continuous waves at 1.5 Hz. The remaining groups were not subjected to EA intervention. The treatment was administered once a day for 7 consecutive days and then executed. We used WB, immunofluorescence, and qRT-PCR to detect the expression of CaMKII/CREB/BDNF signaling pathway-related factors in the synaptic of rat spinal cord in each group.

RESULTS

EA improved pain threshold and motor function in CSR rats, inhibited the expression of BDNF, P-TrkB, CAMKII, and P-CREB in spinal cord synapses, reduced the expression of pain factor c-fos and postsynaptic membrane protein molecule neuroligin2, exerted a modulating effect on spinal cord synaptic plasticity in CSR rats, and suppressed the overactive synaptic efficacy.

CONCLUSION

EA mediates central sensitization and exerts analgesic effects on CSR by modulating spinal synaptic plasticity, which may be related to the inhibition of CaMKII/CREB/BDNF signaling pathway.

Different ratios of Schisandra chinensis and Evodia rutaecarpa combination for treating Alzheimer's disease

Schisandra chinensis and Evodia rutaecarpa are traditional Chinese herbs that have been used for many years to treat neurodegenerative diseases. In Chinese medicine, multiple herbs are often used in combination to enhance their efficacy, and different combination ratios can produce different therapeutic effects, thus flexibly responding to the needs of various patients. This study aimed to investigate the effects of different ratios of Schisandra and Evodia herbs on learning and memory impairment in rats with Alzheimer's disease (AD) and their specific mechanisms of action. Morris water maze and hematoxylin and eosin (HE) staining experiments were performed to evaluate the effects of different ratios of Schisandra-Evodia on learning memory in AD model rats. Immunohistochemical experiments were performed to investigate the effects of Schisandra-Evodia on the Aβ1-42 and P-Tau proteins, and protein immunoblotting (WB) was performed to determine the expression of key proteins in two pathways, BDNF/TrkB/CREB and GSK-3β/Tau. Our experimental results show that all Schisandra-Evodia groups showed significant neuroprotective effects, improved learning memory impairment, and reduced levels of Aβ1-42 and P-Tau proteins in AD model rats. Schisandra-Evodia upregulated BDNF, P-TrkB/TrkB, and P-CREB/CREB protein expression and downregulated GSK-3β and P-Tau/Tau protein expression. Among the different Schisandra-Evodia ratio groups, the 2:1 group showed the strongest therapeutic effect on AD. Our research results indicate that Schisandra-Evodia can reduce Aβ1-42 and P-Tau protein content by modulating the activity of two pathways, BDNF/TrkB/CREB and GSK-3β/Tau, thus improving neuronal cell damage and cognitive deficits caused by AD. In addition, we found that a Schisandra-Evodia ratio of 2:1 had the most profound therapeutic effect on AD.

Naringenin and apigenin ameliorates corticosterone-induced depressive behaviors

Background

Depression is a common kind of mental illness, and it becomes the main health burden in the world.

Purpose

The aim of this study was to investigate the antidepressant effects of naringin and apigenin isolated from Chrysanthemum morifolium Ramatis.

Methods

Firstly, 20 mg/kg corticosterone (CORT) was injected into mice to establish an in vivo model of depression. After treated with different dosages of naringenin and apigenin for 3 weeks, the mice underwent a series of behavioral experiments. Following this, all mice were sacrificed and biochemical analyses were performed. Subsequently, CORT (500 μM) induced PC12 cells was used as an in vitro model of depression, and lipopolysaccharide (LPS) (1 μg ml^-1) induced N9 microglia cells was used as an in vitro model of neuroinflammation in N9 microglia cells, to investigate the neuroprotective mechanisms of naringenin and apigenin.

Results

Results showed that the naringenin and apigenin treatment ameliorated CORT-induced sucrose preference decrease and immobility time increase, elevated the 5-hydroxytryptamine(5-HT), dopamine (DA) and norepinephrine (NE) levels, and enhanced the cAMP-response element binding protein (CREB) and brain derived neurotrophic factor (BDNF) protein expressions in the hippocampus. The results showed that the naringenin and apigenin treatment improved the PC-12 cell viability through reducing apoptosis rate induced by CORT. Furthermore, naringenin and apigenin were able to inhibit the activation of N9 cells after LPS induction, and shift microglia from proinflammatory M1 microglia toward anti-inflammatory M2 microglia, as evidenced by the decreased ratio of M1 type microglia marker CD86 and M2 type microglia marker CD86.

Conclusion

These results suggested that naringenin and apigenin may improve depressive behaviors through promoting BDNF and inhibiting neuroinflammation and neuronal apoptosis.

Microwave assisted free radical degradation of Schisandra polysaccharides: Optimization, identification and application

In order to establish structural-fingerprinting of polysaccharides for improvement of quality assessment, a sample preparation method based on microwave assisted free radical degradation (MFRD) of plant polysaccharides was proposed to produce oligosaccharides and small M_w polysaccharides. As a case study of Schisandra chinensis and S. sphenanthera fruit polysaccharides (SCP and SSP), the MFRD condition (i.e., 100 °C, 30 s and 80 W) was confirmed to be optimal. The potential structures of the MFRD products of SCP and SSP were further discussed by combinations of HILIC-ESI^--QTOF-MS^E and HILIC-ESI^--Q-OT-IT-MS/MS. As followed, multivariable statistical analysis shows a clear separation of SCP and the SSP in PCA and OPLS-DA plots based HILIC-ESI^--QTOF-MS^E data. The VIP plot unveils several key Q-markers (e.g., peaks 3, 8, 9, 10, 15, 25, 26, 28, 29 and 30) with significant differences and stable emergences. Furthermore, a low-polymerization compositional fingerprinting was successfully constructed for SCP and SSP using a high-performance anion-exchange chromatography with pulsed amperometric detection. Compared to the conventional sample preparation methods, the MFRD took only a few thousandth of the time to accomplish degradations of plant polysaccharides. It significantly improves sample preparations and is generally applicable to various polysaccharide samples.

The antidepressant-like effect elicited by vitamin D3 is associated with BDNF/TrkB-related synaptic protein synthesis

Vitamin D₃ (cholecalciferol) has been shown to exert antidepressant-like responses, but the role BDNF/TrkB-related synaptic plasticity in this effect remains to be established. Thus, this study investigated the time-course antidepressant-like response of vitamin D₃ in female and male mice and the possible role of BDNF/TrkB signaling in this response. The repeated (7 and 21 days), but not acute (60 min), administration of vitamin D₃ (2.5 μg/kg, p.o.) exerted an antidepressant-like effect in female and male mice subjected to the tail suspension test, without altering the basal locomotor activity in the open-field test. Notably, vitamin D₃ caused a similar time-dependent antidepressant-like effect in male and female mice, suggesting that this behavioral response in the tail suspension test might not be affected by sex differences. Vitamin D₃ administration for 21 days, but not for 7 days or 1 h, augmented BDNF levels in the hippocampus and prefrontal cortex of mice. No effects on phospho-CREB/CREB levels were detected in the hippocampus and prefrontal cortex after chronic vitamin D₃ administration. Additionally, vitamin D₃ increased TrkB, GluA1, and PSD-95 levels in the prefrontal cortex, but not in the hippocampus. Furthermore, an upregulation of synapsin level was observed in both brain regions after vitamin D₃ administration. These findings reinforce and extend the notion that vitamin D₃ is effective to produce antidepressant-like responses in male and female mice and provide novel evidence that this effect could be associated with BDNF/TrkB-related synaptic protein synthesis. Finally, vitamin D₃ could be a feasible nutritional strategy for the management of depression.

The Corticosterone–Glucocorticoid Receptor–AP1/CREB Axis Inhibits the Luteinizing Hormone Receptor Expression in Mouse Granulosa Cells

Under stress conditions, luteinizing hormone (LH)-mediated ovulation is inhibited, resulting in insufficient oocyte production and excretion during follicular development. When the body is stressed, a large amount of corticosterone (CORT) is generated, which will lead to a disorder of the body’s endocrine system and damage to the body. Our previous work showed that CORT can block follicular development in mice. Since LH acts through binding with the luteinizing hormone receptor (Lhcgr), the present study aimed to investigate whether and how corticosterone (CORT) influences Lhcgr expression in mouse ovarian granulosa cells (GCs). For this purpose, three-week-old ICR female mice were injected intraperitoneally with pregnant mare serum gonadotropin (PMSG). In addition, the treatment group was injected with CORT (1 mg/mouse) at intervals of 8 h and the control group was injected with the same volume of methyl sulfoxide (DMSO). GCs were collected at 24 h, 48 h, and 55 h after PMSG injection. For in vitro experiments, the mouse GCs obtained from healthy follicles were treated with CORT alone, or together with inhibitors against the glucocorticoid receptor (Nr3c1). The results showed that the CORT caused a downregulation of Lhcgr expression in GCs, which was accompanied by impaired cell viability. Moreover, the effect of the CORT was mediated by binding to its receptor (Nr3c1) in GCs. Further investigation revealed that Nr3c1 might regulate the transcription of Lhcgr through inhibiting the expression of Lhcgr transcription factors, including AP1 and Creb. Taken together, our findings suggested a possible mechanism of CORT-induced anovulation involving the inhibition of Lhcgr expression in GCs by the CORT–Nr3c1–AP1/Creb axis.

Oxytocin treatment improves dexamethasone‐induced depression‐like symptoms associated with enhancement of hippocampal CREB‐BDNF signaling in female mice

Aims

Chronic stress and glucocorticoid exposure are risk factors for depression. Oxytocin (OT) has been shown to have antistress and antidepressant‐like effects in male rodents. However, depression is twice as common in women than in men, and it remains unclear whether OT exerts antidepressant‐like effects in women with depression. Therefore, in this study, we investigated the therapeutic effect of chronic OT administration in a female mouse model of dexamethasone (DEX)‐induced depression.

Methods

Female C57BL/6J mice were administered saline (vehicle, s.c.), DEX (s.c.), or OT (i.p.) + DEX (s.c.) daily for 8 weeks, and then assessed for anxiety‐ and depression‐like behaviors. We also examined the hippocampal levels of phosphorylated cAMP response element‐binding protein (p‐CREB) and brain‐derived neurotrophic factor (BDNF), which are important mediators of the response to antidepressants.

Results

Simultaneous OT treatment blocked the adverse effects of DEX on emotional behaviors. Furthermore, it upregulated p‐CREB and BDNF in the hippocampus.

Conclusion

OT may exert antidepressant‐like effects by activating hippocampal CREB‐BDNF signaling in a female mouse model of depression.

The BDNF-TrkB-CREB Signalling Pathway Is Involved in Bisphenol S-Induced Neurotoxicity in Male Mice by Regulating Methylation

Bisphenol S (BPS), the most common substitute for bisphenol A in manufacturing, is associated with neurotoxicity, but its molecular mechanisms are unclear. Here, we studied the role of the BDNF-TrkB-CREB (brain-derived neurotrophic factor-tropomyosin-related kinase B-CAMP response element-binding protein) signalling pathway in bisphenol S-induced neurotoxicity via methylation regulation in male C57BL/6 mice. The mice were treated with sesame oil or 2, 20 and 200 mg/kg body weight BPS for 28 consecutive days, and the hippocampus was extracted. We recorded the body weight, organ index, and hippocampal pathology and ultrastructure of the mice. The BDNF, TrkB, CREB, phosphorylated (p)-CREB, DNMTs (DNA methyltransferases) levels were determined by qRT-PCR and/or Western blotting. BDNF promoter IV methylation level was detected by bisulfite sequencing PCR. BPS damaged the mouse hippocampus ultrastructure and reduced the number of synapses. Further, it increased the methylation rate of BDNF promoter IV; downregulated BDNF, CREB, p-CREB/CREB and DNMT1 expression; and upregulated DNMT3a and DNMT3b expression. Therefore, we speculate that the BDNF-TrkB-CREB pathway may be involved in BPS-induced neurotoxicity in male mice by regulating methylation.

Neuroprotective Effects of Estrogen Through BDNF-Transient Receptor Potential Channels 6 Signaling Pathway in the Hippocampus in a Rat Model of Perimenopausal Depression

Estradiol (E₂) has been proven to be effective in treating perimenopausal depression (PD); however, the downstream signaling pathways have not been fully elucidated. Transient receptor potential channels 6 (TRPC6) plays a vital role in promoting neuronal development and the formation of excitatory synapses. At present, we found that the serum levels of E₂ and brain-derived neurotrophic factor (BDNF) declined significantly in the women with PD compared to perimenopausal women, which was accompanied by a clear reduction in TRPC6 levels. To further reveal the effects of TRPC6 on neuronal survival and excitability, the PD-like rat model was established by the total removal of left ovary and 80% removal of right ovary followed by 21 days of the chronic unpredictable mild stress. Intragastric administration of E₂ (2 mg/kg), intraperitoneal injection of BDNF/TrB signaling pathway inhibitor (K252a, 100 μg/kg) and TRPC6 agonist (OAG, 0.6 mg/kg), and intracerebroventricular infusion of anti-BDNF antibody for blocking BDNF (0.5 μg/24 μl/rat) daily for 21 days were conducted. The levels of BDNF and TRPC6 in rat serum were lower in PD rats compared to the control rats; the depression-like behavior was induced, the neuronal death rate in the hippocampus increased, and the thickness of postsynaptic density (PSD) and the number of asymmetric synapses decreased significantly in the PD group. E₂ treatment greatly upregulated the serum levels of BDNF and TRPC6, the neuronal excitability indicated by an elevation in the PSD thickness and the numbers of asymmetric synapses, and these actions were reversed by K252a; co-administration of TRPC6 agonist and K252a improved neuronal degeneration and increased the neuronal excitability induced in the E₂-treated PD rats. K252a or anti-BDNF antibody inhibited the increased neuronal BDNF and TRPC6 expression in E₂-treated PD rats; co-treatment of TRPC6 agonist and anti-BDNF antibody reduced neuronal death and increased the BDNF and TRPC6 expression in the hippocampal CA1 neurons in the E₂-treated PD rats. These results suggest that the neuroprotective role of E₂ in PD is closely related to enhance the activity of BDNF/TRPC6 pathway and is helpful to provide new prevention and strategies.

Phytochemical identification of Xiaoer Huanglong Granule and pharmacokinetic study in the rat using its seven major bioactive components

Xiaoer Huanglong Granule is the only Chinese Patent Medicine widely used for treating attention deficit hyperactivity disorder. However, not much is known on the bioactive components and pharmacokinetics of Xiaoer Huanglong Granule even after it was successfully introduced into clinical use. This study analyzed the components in the medication and rat plasma after oral administration with the help of UNIFI platform and Masslynx. A total of 119 and 37 components were detected in the medication and plasma, respectively, using ultra performance liquid chromatography - tandem mass spectrometer. We established a rapid and sensitive simultaneous determination of 1 triterpene saponin, 3 monoterpene glycosides, and 3 lignans in rat plasma by solid-phase extraction. The determination was accomplished within 7.50 min via gradient elution. The values of lower limit of quantification were validated at 0.08 ng/mL for tenuifolin, 0.8 ng/mL for lactiflorin, 1.828 ng/mL for albiflorin, 2 ng/mL for paeoniflorin, gomisin B, and gomisin D, 10 ng/mL for schisandrin. The results from validations of other methods were all acceptable (RSD ≤ 14.94%). This is the first report on the identification and pharmacokinetics studies of components in Xiaoer Huanglong Granule. Moreover, the pharmacokinetic behavior of lactiflorin was studied for the first time. This article is protected by copyright. All rights reserved.

Cytotoxic lanostane triterpenoids from the ethanol extract of Schisandra viridis

Three new lanostane triterpenoids, designated as 6-hydroxyl schiglausin A (1), 29-hydroxyl schiglausin D (2), and 6-hydroxyl schiglausin G (3), were isolated from the ethanol extract of the stems of Schisandra viridis. Structural elucidation of all the compounds were performed by spectral methods such as 1D and 2D (¹H-¹H COSY, HMQC, and HMBC) NMR spectroscopy, in addition to high resolution mass spectrometry. The isolated compounds were tested in vitro for cytotoxic activities. As a result, compound 1 exhibited cytotoxic activities for all six tested human lung cancer cell lines with IC₅₀ values less than 10 μM.

Natural products for the treatment of stress-induced depression: Pharmacology, mechanism and traditional use

ETHNOPHARMACOLOGICAL RELEVANCE

Depression, one of the most common psychiatric disorders, is the fourth leading cause of long-term disability worldwide. A series of causes triggered depression, including psychological stress and conflict, as well as biological derangement, among which stress has a pivotal role in the development of depression. Traditional herbal medicine has been used for the treatment of various disorders including depression for a long history with multi-targets, multi-levels and multi-ways, attracting great attention from scholars. Recently, natural products have been commercialized as antidepressants which have become increasingly popular in the world health drug markets. Major research contributions in ethnopharmacology have generated and updated vast amount of data associated with natural products in antidepressant-like activity.

AIMS OF THE REVIEW

This review aims to briefly discuss the pathological mechanism, animal models of stress-induced depression, traditional use of herbal medicines and especially recapitulate the natural products with antidepressant activity and their pharmacological functions and mechanism of action, which may contribute to a better understanding of potential therapeutic effects of natural products and the development of promising drugs with high efficacy and low toxicity for the treatment of stress-induced depression.

MATERIALS AND METHODS

The contents of this review were sourced from electronic databases including PubMed, Sci Finder, Web of Science, Science Direct, Elsevier, Google Scholar, Chinese Knowledge On frastructure (CNKI), Wan Fang, Chinese Scientific and Technological Periodical Database (VIP) and Chinese Biomedical Database (CBM). Additional information was collected from Yao Zhi website (https://db.yaozh.com/). Data were obtained from April 1992 to June 2021. Only English language was applied to the search. The search terms were 'stress-induced depression', 'pathological mechanism' in the title and 'stress', 'depression', 'animal model' and 'natural products' in the whole text.

RESULTS

Stress-induced depression is related to the monoaminergic system, hypothalamic-pituitary-adrenal (HPA) axis, neuronal plasticity and a series of inflammatory factors. Four main types of animal models of stress-induced depression were represented. Fifty-eight bioactive phytochemical compounds, fifty-six herb medicines and five formulas from traditional Chinese medicine were highlighted, which exert antidepressant effects by inhibiting monoamine oxidase (MAO) reaction, alleviating dysfunction of the HPA axis and nerve injury, and possessing anti-inflammatory activities.

CONCLUSIONS

Natural products provide a large number of compounds with antidepressant-like effects, and their therapeutic impacts has been highlighted for a long time. This review summarized the pathological mechanism and animal models of stress-induced depression, and the natural products with antidepressant activity in particular, which will shed light on the action mechanism and clinical potential of these compounds. Natural products also have been a vital and promising source for future antidepressant drug discovery.

A comprehensive review of ethnopharmacology, phytochemistry, pharmacology, and pharmacokinetics of Schisandra chinensis (Turcz.) Baill. and Schisandra sphenanthera Rehd. et Wils

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis (called bei-wuweizi in Chinese, S. chinensis) and Schisandra sphenanthera (called nan-wuweizi in Chinese, S. sphenanthera) are two highly similar plants in the Magnoliaceae family. Their dried ripe fruits are commonly used as traditional Chinese medicine in the treatment of coughs, palpitation, spermatorrhea, and insomnia. They also are traditionally used as tonics in Russia, Japan, and Korea.

AIM OF THE REVIEW

S. chinensis and S. sphenanthera are similar in appearance, traditional applications, ingredient compositions, and therapeutic effects. This review, therefore, aims to provide a systematic insight into the botanical background, ethnopharmacology, phytochemistry, pharmacology, pharmacokinetics, quality control, and toxicology of S. chinensis and S. sphenanthera, and to explore and present the similarities and differences between S. chinensis and S. sphenanthera.

MATERIALS AND METHODS

A comprehensive literature search regarding S. chinensis and S. sphenanthera was collected by using electronic databases including PubMed, SciFinder, Science Direct, Web of Science, CNKI, and the online ethnobotanical database.

RESULTS

In the 2020 Edition of Chinese Pharmacopoeia (ChP), there were 100 prescriptions containing S. chinensis, while only 11 contained S. sphenanthera. Totally, 306 and 238 compounds have been isolated and identified from S. chinensis and S. sphenanthera, respectively. Among these compounds, lignans, triterpenoids, essential oils, phenolic acid, flavonoids, phytosterols are the major composition. Through investigation of pharmacological activities, S. chinensis and S. sphenanthera have similar therapeutic effects including hepatoprotection, neuroprotection, cardioprotection, anticancer, antioxidation, anti-inflammation, and hypoglycemic effect. Besides, S. chinensis turns out to have more effects including reproductive regulation and immunomodulatory, antimicrobial, antitussive and antiasthmatic, anti-fatigue, antiarthritic, and bone remodeling effects. Both S. chinensis and S. sphenanthera have inhibitory effects on CYP3A and P-gp, which can mediate metabolism or efflux of substrates, and therefore interact with many drugs.

CONCLUSIONS

S. chinensis and S. sphenanthera have great similarities. Dibenzocyclooctadiene lignans are regarded to contribute to most of the bioactivities. Schisandrin A-C, schisandrol A-B, and schisantherin A, existing in both S. chinensis and S. sphenanthera but differing in the amount, are the main active components, which may contribute to the similarities and differences. Study corresponding to the traditional use is needed to reveal the deep connotation of the use of S. chinensis and S. sphenanthera as traditional Chinese medicine. In addition, a joint study of S. chinensis and S. sphenanthera can better show the difference between them, which can provide a reference for clinical application. It is worth mentioning that the inhibition of S. chinensis and S. sphenanthera on CYP3A and P-gp may lead to undesirable drug-drug interactions.

Potential Antiviral Action of Alkaloids

Viral infections and outbreaks have become a major concern and are one of the main causes of morbidity and mortality worldwide. The development of successful antiviral therapeutics and vaccines remains a daunting challenge. The discovery of novel antiviral agents is a public health emergency, and extraordinary efforts are underway globally to identify safe and effective treatments for different viral diseases. Alkaloids are natural phytochemicals known for their biological activities, many of which have been intensively studied for their broad-spectrum of antiviral activities against different DNA and RNA viruses. The purpose of this review was to summarize the evidence supporting the efficacy of the antiviral activity of plant alkaloids at half-maximum effective concentration (EC50) or half-maximum inhibitory concentration (IC50) below 10 μM and describe the molecular sites most often targeted by natural alkaloids acting against different virus families. This review highlights that considering the devastating effects of virus pandemics on humans, plants, and animals, the development of high efficiency and low-toxicity antiviral drugs targeting these viruses need to be developed. Furthermore, it summarizes the current research status of alkaloids as the source of antiviral drug development, their structural characteristics, and antiviral targets. Overall, the influence of alkaloids at the molecular level suggests a high degree of specificity which means they could serve as potent and safe antiviral agents waiting for evaluation and exploitation.

A novel ultrasound-assisted vacuum drying technique for improving drying efficiency and physicochemical properties of Schisandra chinensis extract powder

Schisandra chinensis (S. chinensis) extract powder is an important intermediate for the preparation of many prepared medicines and health products. The physicochemical properties of S. chinensis extract powder have been found to vary tremendously and this has been attributed to the long drying time in the traditional drying method. In this study, S. chinensis specimens were authenticated as the dry fruit of S. chinensis (Turcz.) Baill. S. chinensis were extracted twice with 8 L kg-1 (liquid to solid ratio) distilled water. The extracts were mixed and concentrated under reduced pressure to 1.24 g cm-3. Ultrasound-assisted vacuum drying (UAVD) was employed as a new approach to improve the efficiency in drying S. chinensis extract powder and produce a higher quality product. The effects of drying temperature (70, 80, 90°C), ultrasonic power (40, 120, 200 W), and ultrasonic application time (4, 12, 20 min every 20 min) on the kinetics and quality of S. chinensis extract were investigated and compared with the conventional vacuum drying (CVD). It was shown that, with the increase in drying temperature, ultrasonic power, and time of UAVD, the drying time for S. chinensis extract to reach the equilibrium moisture decreased. The drying time was reduced by more than 25% when utilizing UAVD compared to the CVD method. The effective moisture diffusivity (D eff) values for CVD and UAVD were 3.48 × 10-9 m2·s-1 and 7.41 × 10-9 m2 s-1, respectively, at the drying temperature of 80°C, indicating an increase of 112.93%. It was also found that a Weibull distribution model was suitable for predicting the moisture content of S. chinensis extract (R 2 > 0.95). Furthermore, the content of Schisandrol A in the extracts obtained from UAVD was 12.79% higher than that obtained using CVD at 90°C. This demonstrates that UAVD is an efficient drying technique for S. chinensis extract.

Neurogenesis in the rat neonate's hippocampus with maternal short-term REM sleep deprivation restores by royal jelly treatment

BACKGROUND

Numerous studies have shown the effects of rapid eye movement sleep deprivation (REM-SD) on behavior and brain structures. The impact of REM-SD on learning and memory, thus neurogenesis, has been reported in previous studies. Royal jelly (RJ) is known as the wealthiest biological nutrient with various physiological properties. This study aimed to study the possible effect of RJ on neurogenesis of the rat hippocampus neonates following exposure of mother to REM-SD during pregnancy.

METHODS

Thirty neonate rats from 15 pregnant Wistar rats were used. To induce REM-SD, the flowerpot method was used. The pregnant rats were divided into five groups (n = 3): group 1, no treatment; group 2, REM-SD; groups 3, 4, and 5, REM-SD +RJ. The former group received 72 h REM-SD during pregnancy (days 7, 14, 21), and the latter group received REM-SD + RJ (three trial groups). At week 4, the rat neonates of all groups were sacrificed (n = 6 each group). Their brains were fixed, removed, and prepared for Nissl and Hoechst 33342 staining. By using real time polymerase chain reaction methode the brain-derived neurotrophic factor BDNF gene expression was studied (RT-PCR), brain-derived neurotrophic factor (BDNF) gene expression was studied. The results were analyzed statistically, and the Pv  < .05 was considered significant.

RESULTS

The results showed a significant decrease in the number of neurons in the hippocampus of neonatal rats of REM-SD mothers compared to the neonates of the mother with REM-SD + RJ. REM-SD also led to an increase in apoptosis reaching the neonates from the REM-SD + RJ animals. High expression of BDNF was observed in the hippocampus of the neonates from REM-SD + RJ treated mothers.

CONCLUSION

RJ acts as a neuroprotective agent that could compensate for the effects of REM-SD on learning and memory via restoring neurogenesis.

Antidepressant effect of catalpol on corticosterone-induced depressive-like behavior involves the inhibition of HPA axis hyperactivity, central inflammation and oxidative damage probably via dual regulation of NF-κB and Nrf2

This study aimed to investigate the antidepressant effect and mechanism of catalpol on corticosterone (CORT)-induced depressive-like behavior in mice for the first time. As a result, CORT injection induced depressive-like behaviors of mice in behavioral tests, aggravated the serum CORT, adrenocorticotropic hormone, and corticotropin-releasing hormone levels, and conspicuously elevated the phosphorylations of nuclear factor kappa-B (NF-κB) in the hippocampus and frontal cortex, and down-regulated the expression levels of nuclear factor erythroid-2-related factor 2 (Nrf2). Furthermore, CORT exposure dramatically augmented the levels of inflammatory factors (interleukin-1β, tumor necrosis factor-α, nitric oxide synthase, and nitric oxide) and lipid peroxidation product malondialdehyde, and attenuated the levels of antioxidants including reduced glutathione, glutathione S-transferase, total superoxide dismutase, and heme oxygenase-1 in the mouse hippocampus and frontal cortex. On the contrary, catalpol administration markedly suppressed the abnormalities of the above indicators. From the overall results, this study displayed that catalpol exerted a beneficial effect on CORT-induced depressive-like behavior in mice possibly via the inhibition of hypothalamus-pituitary-adrenal (HPA) axis hyperactivity, central inflammation and oxidative damage at least partially through dual regulation of NF-κB and Nrf2.

Medicinal Plants in the Treatment of Depression: Evidence from Preclinical Studies

Medicinal plants and their extracts are natural remedies with enormous potential for treating various diseases, including depression and anxiety. In the case of depression, hundreds of plants have traditionally been used in folk medicine for generations. Different plant extracts and natural products have been analyzed as potential antidepressant agents with validated models to test for antidepressant-like effects in animals, although other complementary studies have also been employed. Most of these studies focus on the possible mediators implicated in these potential effects, with dopamine, serotonin, and noradrenaline being the principal neurotransmitters implicated, both through interference with receptors and with their metabolism by monoamino oxidases, as well as through neuro-endocrine and neuroprotective effects. There are approximately 650 reports of antidepressant-like medicinal plants in PubMed; 155 of them have been compiled in this review, with a relevant group yielding positive results. Saffron and turmeric are the most relevant species studied in both preclinical and clinical studies; St. John's wort or kava have also been tested extensively. To the best of our knowledge, no review to date has provided a comprehensive understanding of the biomolecular mechanisms of action of these herbs or of whether their potential effects could have real benefits. The purpose of this narrative review is to provide an update regarding medicinal plants from the year 2000 to the present to examine the therapeutic potential of these antidepressant-like plants in order to contribute to the development of new therapeutic methods to alleviate the tremendous burden that depression causes worldwide.

Low-polymerization compositional fingerprinting for characterization of Schisandra polysaccharides by hydrophilic interaction liquid chromatography-electrospray mass spectrometry

A hydrophilic interaction liquid chromatography-negative electrospray-mass spectrometry (HILIC-ESI^--MS) coupled with microwave assisted mild acid (MAMA) depolymerization is proposed here for unusual discrimination and characterization of plant polysaccharides: a case study of fruit polysaccharides in Schisandra chinensis and S. sphenanthera (SCP and SSP). The optimized MAMA hydrolysis procedure was proposed for sample preparations of low-polymerization saccharides (M_w < 5000 Da) released in SCP and SSP. In addition, HILIC-MS/MS was employed for elucidation of isomeric glycosidic linkages in terms of ¹⁸O labelling. The MAMA hydrolysates showed that the amount of neutral →(⁴Hex¹)_n→ moiety is confirmed to be more bigger than that of acidic →(⁴HexA¹)_n → in SCP, whereas the amount of acidic →(⁴HexA¹)_n→ moiety seems to be more bigger than that of neutral →(⁴Hex¹)_n→ in SSP. The resulting low-polymerization compositional fingerprinting (LCF) showed the performance on rapid visualization of SCP and SSP by HILIC-MIM-MS. Principal components analysis (PCA) and hierarchical cluster analysis (HCA) further unveils several key Q-markers (e.g., m/z 503, 369, 665, 827, 989, 1151 and 735) for rapid discrimination of SCP and SSP. This practical study showed that the LCF with PCA and HCA could effectively reflect structural differences and could rapidly achieve discrimination of SCP and SSP.

Schisandra chinensis protects against dopaminergic neuronal oxidative stress, neuroinflammation and apoptosis via the BDNF/Nrf2/NF-κB pathway in 6-OHDA-induced Parkinson's disease mice

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by a disorder of both the motor and nonmotor systems due to a loss of dopaminergic (DA) neurons. Herein, we aimed to investigate the potential neuroprotective role of Schisandra chinensis (Sch) and to determine the mechanism by which Sch functions to ameliorate PD in a 6-hydroxydopamin (6-OHDA)-induced PD model. The open field test, sucrose preference test, and Y-maze test were utilized to evaluate the motor and nonmotor symptoms. We found that administration of Sch improved both disorders and DA neurodegeneration in 6-OHDA-induced mice. Additional data confirmed that Sch treatment significantly increased BDNF expression and decreased the activity of GSK-3β in the striatum and hippocampus. Moreover, Sch was able to alleviate the abnormal levels of ROS and increase SOD by boosting Nrf2 expression. The nuclear translocation of NF-κB was inhibited by Sch, which subsequently led to a downregulation of proinflammatory cytokines. Sch effectively suppressed apoptosis by decreasing expressions of caspase 3, caspase 9, and p53 in the PD mouse model. Our findings demonstrate that Sch protects against DA neurodegeneration in 6-OHDA-induced PD mice by suppressing oxidative stress, neuroinflammation and apoptosis through the involvement of the BDNF/Nrf2/NF-κB signaling pathway.

Ninjinyoeito improves anxiety behavior in neuropeptide Y deficient zebrafish

Anxiety induced by excess mental or physical stress is deeply involved in the onset of human psychiatric diseases such as depression, bipolar disorder, and panic disorder. Recently, Kampo medicines have received focus as antidepressant drugs for clinical use because of their synergistic and additive effects. Thus, we evaluated the anxiolytic activity of Ninjinyoeito (NYT) using neuropeptide Y-knockout (NPY-KO) zebrafish that exhibit severe anxiety responses to acute stress. Adult NPY-KO zebrafish were fed either a 3% NYT-supplemented or normal diet (i.e., the control diet) for four days and were then examined via behavioral tests. After short-term cold stress (10 °C, 2 s) was applied, control-fed NPY-KO zebrafish exhibited anxiety behaviors such as freezing, erratic movement, and increased swimming time along the tank wall. On the other hand, NYT-fed NPY-KO zebrafish significantly suppressed these anxiety behaviors, accompanied by a downregulation of tyrosine hydroxylase levels and phosphorylation of extracellular signal-regulated kinases in the brain. To understand the responsible component(s) in NYT, twelve kinds of herbal medicines that composed NYT were tested in behavioral trials with the zebrafish. Among them, nine significantly reduced freezing behavior in NPY-KO zebrafish. In particular, Schisandra fruit induced the most potent effect on abnormal zebrafish behavior, even in the lower amount (0.3% equivalent to NYT), followed by Atractylodes rhizome and Cinnamon bark. Subsequently, four lignans uniquely found in Schisandra fruit (i.e., gomisin A, gomisin N, schizandrin, and schizandrin B) were investigated for their anxiolytic activity in NPY-KO zebrafish. As a result, schizandrin was identified as a responsible compound in the anxiolytic effect of NYT. These results suggest that NYT has a positive effect on mental stress-induced anxiety and may be a promising therapeutic for psychiatric diseases.

Role of the BDNF/TrkB/CREB signaling pathway in the cytotoxicity of bisphenol S in SK-N-SH cells

Bisphenol S (BPS) is associated with neurotoxicity, but its molecular mechanisms are unclear. Our aim was to investigate the role of the brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB)/cAMP-response element-binding protein (CREB) signaling pathway in BPS-induced cytotoxicity in SK-N-SH cells. The cells were treated with various concentrations of BPS, and cell viability, apoptosis rate, mitochondrial membrane potential (MMP), and the BDNF, cleaved-caspase-3, B-cell lymphoma 2 (Bcl-2), Bcl-2-associated X protein (Bax), TrkB, CREB, and phospho-CREB (p-CREB) levels were determined. The effects of pretreatment with the TrkB activator 7,8-dihydroxyflavone (7,8-DHF) were also explored. BPS decreased SK-N-SH cell viability and altered their morphology. Their apoptosis rate was increased, as were the levels of the proapoptotic proteins Bax and cleaved-caspase-3, but MMP was decreased. Thus, BPS may induce mitochondria-dependent apoptosis pathways. BPS also reduced the BDNF, TrkB, and p-CREB levels, and pretreatment with 7,8-DHF alleviated its cytotoxic effects. Thus, BPS-induced cytotoxicity might be mediated by the BDNF/TrkB/CREB signaling pathway.

2-Phenylethylamine (PEA) Ameliorates Corticosterone-Induced Depression-Like Phenotype via the BDNF/TrkB/CREB Signaling Pathway

Depression is a serious medical illness that is one of the most prevalent psychiatric disorders. Corticosterone (CORT) increases depression-like behavior, with some effects on anxiety-like behavior. 2-Phenethylamine (PEA) is a monoamine alkaloid that acts as a central nervous system stimulant in humans. Here, we show that PEA exerts antidepressant effects by modulating the Brain-derived neurotrophic factor (BDNF)/tropomyosin receptor kinase B (TrkB)/cAMP response element binding protein (CREB) signaling pathway in CORT-induced depression. To investigate the potential effects of PEA on CORT-induced depression, we first treated CORT (50 μM)-induced hippocampal neurons with 100 μM PEA for 24 h. We found that treatment with CORT altered dendritic spine architecture; however, treatment with PEA rescued dendritic spine formation via regulation of BDNF/TrkB/CREB signaling. Next, we used a mouse model of CORT-induced depression. Mice were treated with CORT (20 mg/kg) for 21 days, followed by assessments of a battery of depression-like behaviors. During the final four days of CORT exposure, the mice were treated with PEA (50 mg/kg). We found that CORT injection promoted depression-like behavior and significantly decreased BDNF and TrkB expression in the hippocampus. However, treatment with PEA significantly ameliorated the behavioral and biochemical changes induced by CORT. Our findings reveal that PEA exerts antidepressant effects by modulating the BDNF/TrkB/CREB signaling pathway in a mouse model of CORT-induced depression.

Involvement of mTOR-related signaling in antidepressant effects of Sophoraflavanone G on chronically stressed mice

SophoraflavanoneG (SG), an important prenylated flavonoid isolated from Sophoraalopecuroides.L, is effective for many illnesses. The present study was designed to investigate whether the compound could reverse depressive-like symptoms and investigate its possible mechanisms. Chronic Unpredictable Mild Stress (CUMS) mice were treated with fluoxetine and SG. The immobility time in forced swimming test (FST) and tail suspension test (TST) were recorded. The levels of pro-inflammatory cytokines and neurotransmitters in the hippocampus were evaluated. Furthermore, the protein expressions of PI3K, AKT, mTOR, p70S6K, BDNF, and Trkb in hippocampus were detected. Rapamycin, the selective mTOR inhibitor, was used to estimate the potential mechanism. As a result, after 7 days of SG treatment, the immobility time in FST and TST was declined obviously. The levels of IL-6, IL-1β, and TNF-α in the hippocampus were significantly reduced, and the quantity of 5-HT and NE was raised considerably in SG-treated group compared with the CUMS-exposed group. Additionally, SG could up-regulate the expressions of PI3K, AKT, mTOR, 70S6K, BDNF, and Trkb. The blockade of mammalian target of rapamycin signaling blunted the antidepressant effect and reversed the up-regulation of BDNF expression caused by SG. These findings suggested that SG treatment alleviated depressive-like symptoms via mTOR-mediated BDNF/Trkb signaling.

The neuroprotective effect and action mechanism of polyphenols in diabetes mellitus-related cognitive dysfunction

BACKGROUND

Diabetes mellitus (DM) is a complex and prevalent metabolic disorder worldwide. Strong evidence has emerged that DM is a risk factor for the accelerated rate of cognitive decline and the development of dementia. Though traditional pharmaceutical agents are efficient for the management of DM and DM-related cognitive decrement, long-term use of these drugs are along with undesired side effects. Therefore, tremendous studies have focused on the therapeutic benefits of natural compounds at present. Ample evidence exists to prove that polyphenols are capable to modulate diabetic neuropathy with minimal toxicity and adverse effects.

PURPOSE

To describe the benefits and mechanisms of polyphenols on DM-induced cognitive dysfunction. In this review, we introduce an updated overview of associations between DM and cognitive dysfunction. The risk factors as well as pathological and molecular mechanisms of DM-induced cognitive dysfunction are summarized. More importantly, many active polyphenols that possess preventive and therapeutic effects on DM-induced cognitive dysfunction and the potential signaling pathways involved in the action are highlighted.

CONCLUSIONS

The therapeutic effects of polyphenols on DM-related cognitive dysfunction pave a novel way for the management of diabetic encephalopathy.

Synergistic Neuroprotective Effect of Schisandra chinensis and Ribes fasciculatum on Neuronal Cell Death and Scopolamine-Induced Cognitive Impairment in Rats

Mild cognitive impairment (MCI) is considered as a transitional stage between aging and Alzheimer’s disease. In the present study, we examined the protective effect of Schisandra chinensis (SC) and Ribes fasciculatum (RF) on neuronal cell death in vitro and scopolamine-induced cognitive impairment in Sprague Dawley^® rats in vivo. A mixture of SC and RF extracts (SC+RF) significantly protected against hydrogen peroxide-induced PC12 neuronal cell death. The neuroprotective effect of SC+RF on scopolamine-induced memory impairment in rats was evaluated using the passive avoidance test and the Morris water maze test. In the passive avoidance test, SC+RF-treated rats showed an increased latency to escape, compared to the scopolamine-treated rats. Moreover, SC+RF treatment significantly reduced escape latency in water maze test, compared to treatment with scopolamine alone. To verify the long-term memory, we performed probe test of water maze test. As a result, rat treated with SC+RF spent more time in the target quadrant. Consistent with enhancement of memory function, the brain derived neurotrophic factor (BDNF) and its downstream molecules (pERK, pATK, and pCREB) are increased in SC+RF treatment in hippocampal area compared with scopolamine treated group. These results suggest that a mixture of SC and RF extracts may be a good therapeutic candidate for preventing mild cognitive impairment.

(p-ClPhSe)2 modulates hippocampal BDNF/TrkB signaling and reverses memory impairment induced by diabetes in mice

Diabetes is a metabolic disease characterized by hyperglycemia because of insulin resistance and/or insufficient insulin release. The most common diabetic brain complications include cognitive decline and depression. The present study investigated whether the 4-4'-dichlorodiphenyl diselenide (p-ClPhSe)₂ is effective against memory impairment induced by diabetes in mice and the role of hippocampal BDNF/TrkB signaling in this effect. Male adult Swiss mice received an injection of streptozotocin (STZ) (200 mg/kg, i.p.) to induce diabetes. The results revealed that STZ injection in mice resulted in resilience (glycemia <200 mg/dl) or diabetes (glycemia ≥200 mg/dl). The vehicle-control group received citrate buffer (5 ml/kg). The animals were subchronically treated with (p-ClPhSe)₂ (1 or 5 mg/kg, i.g.) for 7 days. Mice performed a battery of well-validated behavior tests designated to evaluate memory, object recognition (ORT), object location (OLT), and Morris water maze (MWM). The hippocampal protein contents of the BDNF/TrkB pathway were determined in the samples of experimental groups. Fluoro Jade C (FJC) was used for staining degenerating neurons. The STZ administration resulted in memory impairment that was demonstrated in the mouse ORT, OLT, and MWM tests. The molecular findings indicate an increase in hippocampal protein levels of proBDNF and TrKB but a decrease in those of mBDNF and pCREB in diabetic mice. The number of FJC-positive cells was increased in the hippocampus of diabetic mice. (p-ClPhSe)₂ at the dose of 5 mg/kg modulated the hippocampal BDNF/TrkB pathway, reduced FJC-positive cells and reversed memory impairment induced by STZ in mice. These findings demonstrate the effectiveness of (p-ClPhSe)₂ against memory impairment caused by diabetes in mice. (p-ClPhSe)₂ modulated the hippocampal BDNF/TrkB signaling pathway in diabetic mice.

Erlotinib inhibits colon cancer metastasis through inactivation of TrkB-dependent ERK signaling pathway

The distal metastasis is the main cause of death in patients with colon cancer. Tyrosine receptor kinase B (TrkB) and ERK signals may be the potential targets for the treatment of colon cancer metastasis. This study aims to investigate whether erlotinib inhibits distant metastasis of colon cancer by regulating TrkB and ERK signaling pathway. Human colon adenocarcinoma cell lines (SW480 and Caco-2) pretreated with exogenous C-X-C motif chemokine ligand 8 (CXCL8) were used to assess the suppressive effect of erlotinib on tumor metastasis, including anoikis, epithelial-mesenchymal transformation (EMT), migration, and invasion. Through TrkB overexpression, Akt suppression, and ERK suppression, the roles of TrkB, Akt, and ERK in erlotinib-induced metastasis inhibition of colon cancer cells were explored. The results showed that erlotinib alleviated CXCL8-induced metastasis of the colon cancer cells. Overexpression of TrkB in colon cancer cells eliminated the effect of erlotinib on anoikis, inhibition of EMT, migration, and invasion, and downregulation of p-ERK and p-Akt. Furthermore, the inhibition of ERK activation instead of Akt activation was found to participate in erlotinib-mediated metastasis resistance, including anoikis, inhibition of EMT, migration, and invasion. In conclusion, erlotinib inhibits colon cancer cell anoikis resistance, EMT, migration, and invasion by inactivating TrkB-dependent ERK signaling pathway.

Mechanisms underpinning AMP-activated protein kinase-related effects on behavior and hippocampal neurogenesis in an animal model of depression

Adenosine monophosphate-activated protein kinase (AMPK) is critical for whole-body energy metabolism regulation. Recent studies have suggested that physical exercise ameliorates depressive-like behaviors via AMPK activation; however, the underlying mechanism is unclear. Here, we examined the effects and underlying mechanisms of AMPK activation on depressive-like behavior in olfactory bulbectomized (OBX) mice. We treated OBX mice with the AMPK activator, 5-aminoimidazole-4-carboxamide-1-β-d-ribonucleotide (AICAR) on the 7th or 14th day after bilateral bulbectomy and evaluated depressive-like behavior using the tail-suspension test (TST) and forced swimming test (FST) on the 21st day. The expression of phosphorylated AMPK, protein kinase C ζ (PKCζ), nuclear factor-kappa B (NF-κB), brain-derived neurotrophic factor (BDNF), and cAMP response element-binding protein (CREB) in the hippocampus was assessed by western blotting. Hippocampal neurogenesis and localization of AMPK and phosphorylated NF-κB were examined by immunohistochemistry. Chronic AICAR treatment suppressed the prolonged immobility of OBX mice in the TST and FST, and increased the levels of phosphorylated AMPK, PKCζ, NF-κB, CREB, and BDNF. Hippocampal neurogenesis in OBX mice was promoted by chronic AICAR treatment. Co-administration of AICAR with the PKCζ inhibitor or the neurotrophic tyrosine kinase receptor type 2 (TrkB) antagonist, ANA-12, inhibited these effects. Phosphorylated AMPK was detected in mature and immature hippocampal neurons and microglia, while phosphorylated NF-κB was detected only in neurons in AICAR-treated OBX mice. These data indicate that AMPK activation produces anti-depressant effects, which are mediated by elevated hippocampal neurogenesis potentially via PKCζ/NF-κB/BDNF/TrkB/CREB signaling in neurons.

Antidepressant-like activities of live and heat-killed Lactobacillus paracasei PS23 in chronic corticosterone-treated mice and possible mechanisms

Emerging evidence indicates that ingestion of specific probiotics, known as "psychobiotics", confer beneficial effects on mental health. This study investigated antidepressant-like effects and possible underlying mechanisms of Lactobacillus paracasei PS23 (PS23), live or heat-killed, in a mouse model of corticosterone-induced depression using fluoxetine as standard drug. PS23 were orally gavaged to mice from day 1 to 41 or fluoxetine from day 17 to 41 and injected with corticosterone from day 17 to 37. After the last corticosterone treatment, anxiety- and depression-like behaviors were tested within 4 days. On day 42, serum and brain tissue were collected 24 min after forced swim stress. Abnormal behavioral changes induced by corticosterone were ameliorated by treatment with live PS23 in open field and sucrose preference tests, with heat-killed PS23 in open field, forced swim and sucrose preference tests, and with fluoxetine in open field and forced swim tests. Furthermore, both live and heat-killed PS23 and fluoxetine reversed corticosterone-reduced protein levels of brain-derived neurotropic factor, mineralocorticoid, and glucocorticoid receptors in the hippocampus. In addition, live PS23 also reverses corticosterone-reduced serotonin levels in hippocampus, prefrontal cortex and striatum; whereas heat-killed PS23 reverses corticosterone-reduced dopamine levels in hippocampus and prefrontal cortex. And fluoxetine normalized reduced corticosterone level in serum. These studies showed that both live and heat-killed PS23 can reverse chronic corticosterone-induced anxiety- and depression-like behaviors and that may provide insights into the mechanism and a potential psychobiotic for depression management.

Identification and characterization of chemical constituents in Dengzhan Shengmai Capsule and their metabolites in rat plasma by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Dengzhan Shengmai Capsule (DZSMC) is a traditional Chinese medicine (TCM) formula with remarkable clinical effect in the treatment of stroke sequelae. Exploring the components of DZSMC and detecting the absorbed prototype constituents and metabolites in blood are of great significance to clarify the effective substances of this prescription. Here, a reliable method using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) was established for the comprehensive analysis of chemical constituents of DZSMC and their metabolites in rat plasma after gastric perfusion. Two acquisition modes, including MS^E mode and Fast DDA mode, were performed for acquiring more precursor ions and cleaner precursor-product ions background during the study of constituents of DZSMC. As a result, a total of 125 constituents were unambiguously characterized or tentatively identified. For the first time, a total of 92 components, including 44 prototype components and 48 metabolites were unambiguously or tentatively identified in rat plasma. The metabolic pathways included phase I reactions (hydration, hydrogenation, oxidation, demethylation and hydroxylation) and phase II reactions (conjugation with glucuronide, sulfate and methyl). Furthermore, the metabolites from caffeic acid and scutellarin were characterized and validated by phase II metabolic reactions in vitro, which could be established as a simulated in vivo environment of metabolites identification and verification of TCM formula. It is the first systematic study on metabolism of DZSMC in vivo and could also provide a valid analytical strategy for characterization of the chemical compounds and metabolites of TCM formula.

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.

Urinary and plasmatic metabolomics strategy to explore the holistic mechanism of lignans in S. chinensis in treating Alzheimer's disease using UPLC-Q-TOF-MS

Schisandra chinensis (Turcz.) Baill (S. chinensis), a functional food, is used as a tonic and sedative agent in traditional Chinese medicine.

Cortisol and Major Depressive Disorder-Translating Findings From Humans to Animal Models and Back

Major depressive disorder (MDD) is a global problem for which current pharmacotherapies are not completely effective. Hypothalamic-pituitary-adrenal (HPA) axis dysfunction has long been associated with MDD; however, the value of assessing cortisol as a biological benchmark of the pathophysiology or treatment of MDD is still debated. In this review, we critically evaluate the relationship between HPA axis dysfunction and cortisol level in relation to MDD subtype, stress, gender and treatment regime, as well as in rodent models. We find that an elevated cortisol response to stress is associated with acute and severe, but not mild or atypical, forms of MDD. Furthermore, the increased incidence of MDD in females is associated with greater cortisol response variability rather than higher baseline levels of cortisol. Despite almost all current MDD treatments influencing cortisol levels, we could find no convincing relationship between cortisol level and therapeutic response in either a clinical or preclinical setting. Thus, we argue that the absolute level of cortisol is unreliable for predicting the efficacy of antidepressant treatment. We propose that future preclinical models should reliably produce exaggerated HPA axis responses to acute or chronic stress a priori, which may, or may not, alter baseline cortisol levels, while also modelling the core symptoms of MDD that can be targeted for reversal. Combining genetic and environmental risk factors in such a model, together with the interrogation of the resultant molecular, cellular, and behavioral changes, promises a new mechanistic understanding of MDD and focused therapeutic strategies.

Prefrontal cortical trkB, glucocorticoids, and their interactions in stress and developmental contexts

The tropomyosin/tyrosine receptor kinase B (trkB) and glucocorticoid receptor (GR) regulate neuron structure and function and the hormonal stress response. Meanwhile, disruption of trkB and GR activity (e.g., by chronic stress) can perturb neuronal morphology in cortico-limbic regions implicated in stressor-related illnesses like depression. Further, several of the short- and long-term neurobehavioral consequences of stress depend on the developmental timing and context of stressor exposure. We review how the levels and activities of trkB and GR in the prefrontal cortex (PFC) change during development, interact, are modulated by stress, and are implicated in depression. We review evidence that trkB- and GR-mediated signaling events impact the density and morphology of dendritic spines, the primary sites of excitatory synapses in the brain, highlighting effects in adolescents when possible. Finally, we review the role of neurotrophin and glucocorticoid systems in stress-related metaplasticity. We argue that better understanding the long-term effects of developmental stressors on PFC trkB, GR, and related factors may yield insights into risk for chronic, remitting depression and related neuropsychiatric illnesses.

Sex-Dependent Effects of Environmental Enrichment on Spatial Memory and Brain-Derived Neurotrophic Factor (BDNF) Signaling in a Developmental "Two-Hit" Mouse Model Combining BDNF Haploinsufficiency and Chronic Glucocorticoid Stimulation

Neurodevelopmental disorders are thought to be caused by a combination of adverse genetic and environmental insults. The "two-hit" hypothesis suggests that an early first "hit" primes the developing brain to be vulnerable to a second "hit" during adolescence which triggers behavioral dysfunction. We have previously modeled this scenario in mice and found that the combined effect of a genetic hapolinsuffuciency in the brain-derived neurotrophic factor (BDNF) gene (1st hit) and chronic corticosterone (CORT) treatment during adolescence (2nd hit), caused spatial memory impairments in adulthood. Environmental enrichment (EE) protocols are designed to stimulate experience-dependent plasticity and have shown therapeutic actions. This study investigated whether EE can reverse these spatial memory impairments. Wild-type (WT) and BDNF heterozygous (HET) mice were treated with corticosterone (CORT) in their drinking water (50 mg/L) from weeks 6 to 8 and exposed to EE from 7 to 9 weeks. Enriched housing included open top cages with additional toys, tunnels, housing, and platforms. Y-maze novel preference testing, to assess short-term spatial memory, was performed at 10 weeks of age. At week 16 dorsal hippocampus tissue was obtained for Western blot analysis of expression levels of BDNF, the BDNF receptor TrkB, and NMDA receptor subunits, GluNR1, 2A and 2B. As in our previous studies, spatial memory was impaired in our two-hit (BDNF HET + CORT) mice. Simultaneous EE prevented these impairments. However, EE appeared to worsen spatial memory performance in WT mice, particularly those exposed to CORT. While BDNF levels were lower in BDNF HET mice as expected, there were no further effects of CORT or EE in males but a close to significant female CORT × EE × genotype interaction which qualitatively corresponded with Y-maze performance. However, EE caused both sex- and genotype-specific effects on phosphorylated TrkB residues and GluNR expression within the dorsal hippocampus, with GluNR2B levels in males changing in parallel with spatial memory performance. In conclusion, beneficial effects of EE on spatial memory emerge only following two developmental disruptions. The mechanisms by which EE exerts its effects are likely via regulation of multiple activity-dependent pathways, including TrkB and NMDA receptor signaling.

Cytotoxic lanostane triterpenoids from the stems of Schisandra glaucescens

Phytochemical investigation on the stems of Schisandra glaucescens resulted into the isolation of three new lanostane triterpenoids, 12-hydroxyschiglausin B (1), 12-hydroxykadsuphilactone B (2), and 20R-hydroxyschinalactone C (3). Structural elucidation of all the compounds was accomplished by spectral methods. The isolated compounds were tested in vitro for cytotoxic activities. As a result, triterpenoids 1 and 2 showed cytotoxic activities for all six tested tumor cell lines with IC₅₀ values less than 15 μM.

Schisandra chinensis Fructus and Its Active Ingredients as Promising Resources for the Treatment of Neurological Diseases

Neurological diseases (NDs) are a leading cause of death worldwide and tend to mainly affect people under the age of 50. High rates of premature death and disability caused by NDs undoubtedly constrain societal development. However, effective therapeutic drugs and methods are very limited. Schisandra chinensis Fructus (SCF) is the dry ripe fruit of Schisandra chinensis (Turcz.) Baill, which has been used in traditional Chinese medicine for thousands of years. Recent research has indicated that SCF and its active ingredients show a protective role in NDs, including cerebrovascular diseases, neurodegenerative diseases, or depression. The key neuroprotective mechanisms of SCF and its active ingredients have been demonstrated to include antioxidation, suppression of apoptosis, anti-inflammation, regulation of neurotransmitters, and modulation of brain-derived neurotrophic factor (BDNF) related pathways. This paper summarizes studies of the role of SCF and its active ingredients in protecting against NDs, and highlights them as promising resources for future treatment. Furthermore, novel insights on the future challenges of SCF and its active ingredients are offered.

Cholecalciferol counteracts depressive-like behavior and oxidative stress induced by repeated corticosterone treatment in mice

Depression is one of the most frequent neuropsychiatric diseases in the western world and its physiological causes are not yet fully understood. Since the available antidepressants failed to provide a complete illness remission, the diversification of the therapy in the management of depression could be a useful contribution. The present study aimed to investigate the cholecalciferol capability to revert depressive-like behavior induced by chronic corticosterone (CORT) treatment in mice and its implication on the oxidative stress modulation. Sixty minutes after having orally received different doses of cholecalciferol, adult male mice were evaluated in the forced swimming and tail suspension tests, whereas in the seven-day treatment they were only tested in tail suspension. Additionally, for 21 days, the animals received CORT (20 mg/kg, p.o.) and cholecalciferol or fluoxetine, once a day for the last 7-days of the CORT treatment. Moreover, the markers of oxidative stress, lipid peroxidation, protein carbonyl and nitrite levels were assessed in the plasma and brain's mice after the splash and tail suspension tests. It was observed that corticosterone treatment resulted in depressive-like behavior with established oxidative stress in mice, while cholecalciferol ameliorated both, behavioral (immobility time and grooming latency) and biochemical (protein carbonyl and nitrite levels) changes induced by CORT model, suggesting that cholecalciferol has antidepressant-like effect with the involvement of the oxidative stress modulation.