BDNF and COX-2 participate in anti-depressive mechanisms of catalpol in rats undergoing chronic unpredictable mild stress. Physiol Behav. 2015;151:360-368. [PMID: 26255123 DOI: 10.1016/j.physbeh.2015.08.008]

Comparing the effect of fluoxetine, escitalopram, and sertraline, on the level of BDNF and depression in preclinical and clinical studies: a systematic review

Brain-derived neurotrophic factor (BDNF) dysfunction is one of the most important mechanisms underlying depression. It seems that selective serotonin reuptake inhibitors (SSRIs) improve depression via affecting BDNF level. In this systematic review, for the first time, we aimed to review the effect of three SSRIs including fluoxetine, escitalopram, and sertraline, on both depression and BDNF level in preclinical and clinical studies. PubMed electronic database was searched, and 193 articles were included in this study. After reviewing all manuscripts, only one important difference was found: subjects. We found that SSRIs induce different effects in animals vs. humans. Preclinical studies showed many controversial effects, while human studies showed only two effects: improvement of depression, with or without the improvement of BDNF. However, most studies used chronic SSRIs treatment, while acute SSRIs were not effectively used and evaluated. In conclusion, it seems that SSRIs are reliable antidepressants, and the improvement effect of SSRIs on depression is not dependent to BDNF level (at least in human studies).

Catalpol reduced LPS induced BV2 immunoreactivity through NF-κB/NLRP3 pathways: an in Vitro and in silico study

Background: Ischemic Stroke (IS) stands as one of the primary cerebrovascular diseases profoundly linked with inflammation. In the context of neuroinflammation, an excessive activation of microglia has been observed. Consequently, regulating microglial activation emerges as a vital target for neuroinflammation treatment. Catalpol (CAT), a natural compound known for its anti-inflammatory properties, holds promise in this regard. However, its potential to modulate neuroinflammatory responses in the brain, especially on microglial cells, requires comprehensive exploration. Methods: In our study, we investigated into the potential anti-inflammatory effects of catalpol using lipopolysaccharide (LPS)-stimulated BV2 microglial cells as an experimental model. The production of nitric oxide (NO) by LPS-activated BV2 cells was quantified using the Griess reaction. Immunofluorescence was employed to measure glial cell activation markers. RT-qPCR was utilized to assess mRNA levels of various inflammatory markers. Western blot analysis examined protein expression in LPS-activated BV2 cells. NF-κB nuclear localization was detected by immunofluorescent staining. Additionally, molecular docking and molecular dynamics simulations (MDs) were conducted to explore the binding affinity of catalpol with key targets. Results: Catalpol effectively suppressed the production of nitric oxide (NO) induced by LPS and reduced the expression of microglial cell activation markers, including Iba-1. Furthermore, we observed that catalpol downregulated the mRNA expression of proinflammatory cytokines such as IL-6, TNF-α, and IL-1β, as well as key molecules involved in the NLRP3 inflammasome and NF-κB pathway, including NLRP3, NF-κB, caspase-1, and ASC. Our mechanistic investigations shed light on how catalpol operates against neuroinflammation. It was evident that catalpol significantly inhibited the phosphorylation of NF-κB and NLRP3 inflammasome activation, both of which serve as upstream regulators of the inflammatory cascade. Molecular docking and MDs showed strong binding interactions between catalpol and key targets such as NF-κB, NLRP3, and IL-1β. Conclusion: Our findings support the idea that catalpol holds the potential to alleviate neuroinflammation, and it is achieved by inhibiting the activation of NLRP3 inflammasome and NF-κB, ultimately leading to the downregulation of pro-inflammatory cytokines. Catalpol emerges as a promising candidate for the treatment of neuroinflammatory conditions.

Co-catalpol alleviates fluoxetine-induced main toxicity: Involvement of ATF3/FSP1 signaling-mediated inhibition of ferroptosis

BACKGROUND

Fluoxetine is often used as a well-known first-line antidepressant. However, it is accompanied with hepatogenic injury as its main organ toxicity, thereby limiting its application despite its superior efficacy. Fluoxetine is commonly traditionally used combined with some Chinese antidepressant prescriptions containing Rehmannia glutinosa (Dihuang) for depression therapy and hepatoprotection. Our previous experiments showed that co-Dihuang can alleviate fluoxetine-induced liver injury while efficiencies, and catalpol may be the key ingredient to characterize the toxicity-reducing and synergistic effects. However, whether co-catalpol can alleviate fluoxetine-induced liver injury and its toxicity-reducing mechanism remain unclear.

PURPOSE

On the basis of the first recognition of the dose and duration at which pre-fluoxetine caused hepatic injury, co-catalpol's alleviation of fluoxetine-induced hepatic injury and its pathway was comprehensively elucidated.

METHOD AND RESULTS

The hepatoprotection of co-catalpol was evaluated by serum biochemical indexes sensitive to hepatic injury and multiple staining techniques for hepatic pathologic analysis. Subsequently, the pathway by which catalpol alleviated fluoxetine-induced hepatic injury was predicted by network pharmacology to be predominantly the inhibition of ferroptosis. These were validated and confirmed in subsequent experiments with key technologies and diagnostic reagents related to ferroptosis. Further molecular docking showed that activating transcription factor 3 (ATF3) and ferroptosis suppressor protein 1 (FSP1) were the the most prospective molecules for catalpol and fluoxetine among many ferroptosis-related molecules. The critical role of ATF3/FSP1 signaling was further observed by surface plasmon resonance, diagnostic reagents, transmission electron microscopy, Western blot, real-time PCR, immunofluorescence, and immunohistochemistry. Results showed that fluoxetine directly bound to ATF3 and FSP1; agonisting ATF3 or blocking FSP1 abolished the alleviation of catalpol on fluoxetine-induced liver injury, and both exacerbated ferroptosis. Moreover, co-catalpol significantly enhanced the antidepressant efficacy of fluoxetine against depressive behaviours in mice.

CONCLUSION

The hepatic impairment properties of fluoxetine were largely dependent on ATF3/FSP1 target-mediated ferroptosis. Co-catalpol alleviated fluoxetine-induced hepatic injury while enhancing its antidepressant efficacy, and that ATF3/FSP1 signaling-mediated inhibition of ferroptosis was involved in its co-administration detoxification mechanism. This study was the first to reveal the hepatotoxicity characteristics, targets, and mechanisms of fluoxetine; provide a detoxification and efficiency regimen by co-catalpol; and elucidate the detoxification mechanism.

Neuroprotective effects of Rehmannia glutinosa polysaccharide on chronic constant light (CCL)-induced oxidative stress and autophagic cell death via the AKT/mTOR pathway in mouse hippocampus and HT-22 cells

Rehmannia glutinosa polysaccharide (RGP) has been reported to exhibit anti-anxiety effects, yet the underlying mechanism remains unclear. Chronic constant light (CCL) induced cognitive dysfunction associated with oxidative stress in mice has been reported. Here, the neuroprotective effect of RGP on hippocampal neuron damage in CCL-treated mice was investigated. In vivo study, mice were subjected to CCL for 4 weeks and/or oral administration of 100, 200 and 400 mg/kg RGP every other day. In vitro experiment, hippocampal neuron cells (HT-22) was exposed to LED light and/or supplemented with 62.5, 125 and 250 μg/mL RGP. Mice exposed to CCL showed impaired cognitive and depressive-like behavior in the hippocampus, which were reversed by RGP. Meanwhile, RGP reversed light-induced oxidative stress and autophagy both in mice and hippocampal neuron cells (HT-22). Furthermore, compared with Light-exposed group, RGP treatment activated the AKT/mTOR pathway. Importantly, the AKT inhibitor Perifosine significantly weakened the neuroprotective of RGP on Light-induced oxidative stress and autophagy in HT-22 cells by inhibiting AKT/mTOR pathway and increasing the content of autophagy-related protein. Our data demonstrated, for the first time, that oxidative stress and the AKT/mTOR pathway plays a critical role in Light-induced apoptosis and autophagic cell death in mice and HT-22 cells.

Catalpol rescues LPS-induced cognitive impairment via inhibition of NF-Κb-regulated neuroinflammation and up-regulation of TrkB-mediated BDNF secretion in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Septic-associated encephalopathy (SAE) is a key manifestation of sepsis. Nevertheless, specific treatment for SAE is still lacking. Catalpol is an active component derived from Rehmanniae Radix, and has been demonstrated to be a potential neuroprotective agent. However, its effect on SAE still needs to be fully explored.

AIM

To address the benefits of catalpol on post-sepsis cognitive deterioration and related mechanisms.

MATERIALS AND METHODS

Novel object recognition test, temporal order task, histopathology, and immunochemistry were applied to address the benefits of catalpol on LPS-triggered post-sepsis cognitive decline in mice. Xuebijing injection (10 ml/kg) has been utilized as a positive control in the above animal studies. After treatment, the catalpol content in the hippocampus was determined using LC-MS/MS. Finally, the mechanisms of catalpol were further assessed in BV2 and PC12 cells in vitro using Western blot, RT-PCR, flow cytometry, molecular docking tests, thermal shift assay, transmission electron microscopy, and immunofluorescence analysis.

RESULTS

Behavior tests showed that catalpol therapy could lessen the cognitive impairment induced by LPS damage. HE, Nissl, immunofluorescence, transmission electron microscopy, and Golgi staining further reflected that catalpol treatment could restore lymphocyte infiltration, blood-brain barrier (BBB) degradation, and the decreasing complexity of dendritic trees. According to LC-MS/MS analysis, catalpol had a 136 ng/mg concentration in the hippocampus. In vitro investigation showed that catalpol could inhibit microglia M1 polarization via blocking NF-κB phosphorylation, translocation and then reducing inflammatory cytokine release in BV2 microglia cells. Brain-derived neurotrophic factor (BDNF) release up-regulation and TrkB pathway activation were observed in the catalpol treatment group in vivo and in vitro. The effect of catalpol on enhancing BDNF expression was inhibited by the specific inhibitor of TrkB (GNF-5837) in PC12 cells. Further molecular docking tests showed that catalpol formed weak hydrophobic bonds with TrkB. Besides, thermal shift assay also reflected that catalpol incubation caused a considerable change in the melting temperature of the TrkB.

CONCLUSION

Catalpol alleviates LPS-triggered post-sepsis cognitive impairment by reversing neuroinflammation via blocking the NF-κB pathway, up-regulating neurotrophic factors via the activation of TrkB pathway, and preserving BBB integrity.

Physical Activity and Cognitive Functioning

Neuroscience applied to motor activity is a growing area that aims to understand the effects of motor activity on the structures and functions of the Central Nervous System. Attention has been paid to this multidisciplinary field of investigation by the scientific community both because it is of great importance in the treatment of many chronic diseases and because of its potential applications in the Movement Sciences. Motor activity during a developmental age is, in fact, an indispensable tool for the physical and mental growth of children, both able-bodied and disabled. Through movement, individuals can improve their physical efficiency and promote their own better health, establish relationships with the environment and others, express themselves and their emotions, form their identity and develop cognitive processes. This literature review aims, therefore, to highlight how an adequate practice of motor activity offers extraordinary possibilities for everyone in relation to learning, from the perspective of an integral development of the person, and, consequently, can raise the awareness of those involved in the training and growth, especially the youngest, towards the educational value of motor and sports activities. According to this review, and in line with the modern neuroscientific approach toward the relationships between motor activities and cognitive functions, it is possible to claim that hypokinesia tends to inhibit learning. Therefore, it now seems more topical than ever to draw attention to the need to introduce working proposals that integrate brain-based motor activity programs into the school curriculum.

Transcriptome Analysis Provides Insights into Catalpol Biosynthesis in the Medicinal Plant Rehmannia glutinosa and the Functional Characterization of RgGES Genes

Rehmannia glutinosa, a member of the Scrophulariaceae family, has been widely used in traditional Chinese medicine since ancient times. The main bioactive component of R. glutinosa is catalpol. However, the biogenesis of catalpol, especially its downstream pathway, remains unclear. To identify candidate genes involved in the biosynthesis of catalpol, transcriptomes were constructed from R. glutinosa using the young leaves of three cultivars, Beijing No. 3, Huaifeng, and Jin No. 9, as well as the tuberous roots and adventitious roots of the Jin No. 9 cultivar. As a result, 71,142 unigenes with functional annotations were generated. A comparative analysis of the R. glutinosa transcriptomes identified over 200 unigenes of 13 enzymes potentially involved in the downstream steps of catalpol formation, including 9 genes encoding UGTs, 13 for aldehyde dehydrogenases, 70 for oxidoreductases, 44 for CYP450s, 22 for dehydratases, 30 for decarboxylases, 19 for hydroxylases, and 10 for epoxidases. Moreover, two novel genes encoding geraniol synthase (RgGES), which is the first committed enzyme in catalpol production, were cloned from R. glutinosa. The purified recombinant proteins of RgGESs effectively converted GPP to geraniol. This study is the first to discover putative genes coding the tailoring enzymes mentioned above in catalpol biosynthesis, and functionally characterize the enzyme-coding gene in this pathway in R. glutinosa. The results enrich genetic resources for engineering the biosynthetic pathway of catalpol and iridoids.

Neurotrophic basis to the pathogenesis of depression and phytotherapy

Depression is a major neuropsychiatric disease that considerably impacts individuals’ psychosocial function and life quality. Neurotrophic factors are now connected to the pathogenesis of depression, while the definitive neurotrophic basis remains elusive. Besides, phytotherapy is alternative to conventional antidepressants that may minimize undesirable adverse reactions. Thus, further research into the interaction between neurotrophic factors and depression and phytochemicals that repair neurotrophic factors deficit is highly required. This review highlighted the implication of neurotrophic factors in depression, with a focus on the brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), vascular endothelial growth factor (VEGF), and nerve growth factor (NGF), and detailed the antidepressant activities of various phytochemicals targeting neurotrophic factors. Additionally, we presented future opportunities for novel diagnostic and therapeutic strategies for depression and provided solutions to challenges in this area to accelerate the clinical translation of neurotrophic factors for the treatment of depression.

Licochalcone A Inhibits Prostaglandin E2 by Targeting the MAPK Pathway in LPS Activated Primary Microglia

Neuroinflammation and oxidative stress are conditions leading to neurological and neuropsychiatric disorders. Natural compounds exerting anti-inflammatory and anti-oxidative effects, such as Licochalcone A, a bioactive flavonoid present in a traditional Chinese herb (licorice), might be beneficial for the treatment of those disorders. Therefore, this study aimed to investigate the anti-inflammatory and anti-oxidative effects of Licochalcone A in LPS-activated primary rat microglia. Licochalcone A dose-dependently prevented LPS-induced PGE₂ release by inhibiting the arachidonic acid (AA)/cylcooxygenase (COX) pathway decreasing phospholipase A2, COX-1, and COX-2 protein levels. Furthermore, LPS-induced levels of the cytokines IL-6 and TNFα were reduced by Licochalcone A, which also inhibited the phosphorylation and, thus, activation of the mitogen-activated protein kinases (MAPK) p38 MAPK and Erk 1/2. With the reduction of 8-iso-PGF_2α, a sensitive marker for oxidative stress, anti-oxidative effects of Licochalcone A were demonstrated. Our data demonstrate that Licochalcone A can affect microglial activation by interfering in important inflammatory pathways. These in vitro findings further demonstrate the potential value of Licochalcone A as a therapeutic option for the prevention of microglial dysfunction related to neuroinflammatory diseases. Future research should continue to investigate the effects of Licochalcone A in different disease models with a focus on its anti-oxidative and anti-neuroinflammatory properties.

Therapeutic treatment with fluoxetine using the chronic unpredictable stress model induces changes in neurotransmitters and circulating miRNAs in extracellular vesicles

The most widely prescribed antidepressant, fluoxetine (FLX), is known for its antioxidant and anti-inflammatory effects when administered post-stress. Few studies have evaluated the effects of FLX treatment when chronic stress has induced deleterious effects in patients. Our objective was to evaluate FLX treatment (20 mg/kg/day, i.v.) once these effects are manifested, and the drug's relation to extracellular circulating microRNAs associated with inflammation, a hedonic response (sucrose intake), the forced swim test (FST), and corticosterone levels (CORT) and monoamine concentrations in limbic areas. A group of Wistar rats was divided into groups: Control; FLX; CUMS (for six weeks of exposure to chronic, unpredictable mild stress); and CUMS + FLX, a mixed group. After CUMS, the rats performed the FST, and serum levels of CORT and six microRNAs (miR-16, -21, -144, -155, -146a, -223) were analyzed, as were levels of dopamine, noradrenaline, and serotonin in the prefrontal cortex, hippocampus, and hypothalamus. CUMS reduced body weight, sucrose intake, and hippocampal noradrenaline levels, but increased CORT, immobility behavior on the FST, dopamine concentrations in the prefrontal cortex, and all miRNAs except miR-146a expression. Administering FLX during CUMS reduced CORT levels and immobility behavior on the FST and increased the expression of miR-16, -21, -146a, -223, and dopamine. FLX protects against the deleterious effects of stress by reducing CORT and has an antidepressant effect on the FST, with minimally-modified neurotransmitter levels. FLX increased the expression of miRNAs as part of the antidepressant effect. It also regulates both neuroinflammation and serotoninergic neurotransmission through miRNAs, such as the miR-16.

Therapeutic potential of plant iridoids in depression: a review

CONTEXT

Depression is a mental disorder characterized by low mood, reduced interest, impaired cognitive function, and vegetative symptoms such as sleep disturbances or poor appetite. Iridoids are the active constituents in several Chinese classical antidepressant formulae such as Yueju Pill, Zhi-Zi-Hou-Po Decoction, Zhi-Zi-Chi Decoction, and Baihe Dihuang Decoction. Parallel to their wide usages, iridoids are considered potential lead compounds for the treatment of neurological diseases.

OBJECTIVE

The review summarizes the therapeutic potential and molecular mechanisms of iridoids in the prevention or treatment of depression and contributes to identifying research gaps in iridoids as potential antidepressant medication.

METHODS

The following key phrases were sought in PubMed, Google Scholar, Web of Science, and China National Knowledge Internet (CNKI) without time limitation to search all relevant articles with in vivo or in vitro experimental studies as comprehensively as possible: ('iridoid' or 'seciridoid' or 'depression'). This review extracted the experimental data on the therapeutic potential and molecular mechanism of plant-derived iridoids for depression.

RESULTS

Plant iridoids (i.e., catalpol, geniposide, loganin), and secoiridoids (i.e., morroniside, gentiopicroside, oleuropein, swertiamarin), all showed significant improvement effects on depression.

DISCUSSION AND CONCLUSIONS

Iridoids exert antidepressant effects by elevating monoamine neurotransmitters, reducing pro-inflammatory factors, inhibiting hypothalamic-pituitary-adrenal (HPA) axis hyperactivity, increasing brain-derived neurotrophic factor (BDNF) and its receptors, and elevating intestinal microbial abundance. Further detailed studies on the pharmacokinetics, bioavailability, and key molecular targets of iridoids are also required in future research, ultimately to provide improvements to current antidepressant medications.

Novel TRKB agonists activate TRKB and downstream ERK and AKT signaling to protect Aβ-GFP SH-SY5Y cells against Aβ toxicity

Decreased BDNF and impaired TRKB signaling contribute to neurodegeneration in Alzheimer’s disease (AD). We have shown previously that coumarin derivative LM-031 enhanced CREB/BDNF/BCL2 pathway. In this study we explored if LM-031 analogs LMDS-1 to -4 may act as TRKB agonists to protect SH-SY5Y cells against Aβ toxicity. By docking computation for binding with TRKB using 7,8-DHF as a control, all four LMDS compounds displayed potential of binding to domain d5 of TRKB. In addition, all four LMDS compounds exhibited anti-aggregation and neuroprotective efficacy on SH-SY5Y cells with induced Aβ-GFP expression. Knock-down of TRKB significantly attenuated TRKB downstream signaling and the neurite outgrowth-promoting effects of these LMDS compounds. Among them, LMDS-1 and -2 were further examined for TRKB signaling. Treatment of ERK inhibitor U0126 or PI3K inhibitor wortmannin decreased p-CREB, BDNF and BCL2 in Aβ-GFP cells, implicating the neuroprotective effects are via activating TRKB downstream ERK, PI3K-AKT and CREB signaling. LMDS-1 and -2 are blood–brain barrier permeable as shown by parallel artificial membrane permeability assay. Our results demonstrate how LMDS-1 and -2 are likely to work as TRKB agonists to exert neuroprotection in Aβ cells, which may shed light on the potential application in therapeutics of AD.

Integrated network pharmacology and hepatic metabolomics to reveal the mechanism of Acanthopanax senticosus against major depressive disorder

Objective:Acanthopanax senticosus (Rupr. et Maxim.) Harms (ASH) is a traditional herbal medicine widely known for its antifatigue and antistress effects, as well as tonifying qi, invigorating spleen and kidney, and tranquilizing the mind. Recent evidence suggests that ASH has a therapeutic effect on major depressive disorder (MDD), but its mechanism is still unclear. The current study aimed to investigate the effect of ASH on MDD and potential therapeutic mechanisms.

Materials and Methods: The chemical compound potential target network was predicted based on network pharmacology. Simultaneously, chronic unpredictable mild stress (CUMS) model mice were orally administrated ASH with three dosages (400, 200, and 100 mg/kg) for 6 weeks, and hepatic metabolomics based on gas chromatography–mass spectrometry (GC–MS) was carried out to identify differential metabolites and related metabolic pathways. Next, the integrated analysis of metabolomics and network pharmacology was applied to find the key target. Finally, molecular docking technology was employed to define the combination of the key target and the corresponding compounds.

Results: A total of 13 metabolites and four related metabolic pathways were found in metabolomics analysis. From the combined analysis of network pharmacology and metabolomics, six targets (DAO, MAOA, MAOB, GAA, HK1, and PYGM) are the overlapping targets and two metabolic pathways (glycine, serine, and threonine metabolism and starch and sucrose metabolism) are the most related pathways. Finally, DAO, MAOA, MAOB, GAA, HK1, and PYGM were verified bounding well to their corresponding compounds including isofraxidin, eleutheroside B1, eleutheroside C, quercetin, kaempferol, and acacetin.

Conclusion: Based on these results, it was implied that the potential mechanism of ASH on MDD was related to the regulation of metabolism of several excitatory amino acids and carbohydrates, as well as the expression of DAO, MAOA, MAOB, GAA, HK1, and PYGM.

Microglia in depression: an overview of microglia in the pathogenesis and treatment of depression

Major depressive disorder is a highly debilitating psychiatric disorder involving the dysfunction of different cell types in the brain. Microglia are the predominant resident immune cells in the brain and exhibit a critical role in depression. Recent studies have suggested that depression can be regarded as a microglial disease. Microglia regulate inflammation, synaptic plasticity, and the formation of neural networks, all of which affect depression. In this review, we highlighted the role of microglia in the pathology of depression. First, we described microglial activation in animal models and clinically depressed patients. Second, we emphasized the possible mechanisms by which microglia recognize depression-associated stress and regulate conditions. Third, we described how antidepressants (clinical medicines and natural products) affect microglial activation. Thus, this review aimed to objectively analyze the role of microglia in depression and focus on potential antidepressants. These data suggested that regulation of microglial actions might be a novel therapeutic strategy to counteract the adverse effects of devastating mental disorders.

Catalpol Exerts Antidepressant-Like Effects by Enhancing Anti-oxidation and Neurotrophy and Inhibiting Neuroinflammation via Activation of HO-1

Catalpol is an iridoid glycoside with rich content, rich nutrition, and numerous biological activities in Rehmanniae Radix contained in classic antidepressant prescriptions in Chinese clinical medicine. Catalpol has been confirmed previously its exact antidepressant-like effect involved heme oxygenase (HO)-1, but its antidepressant molecular targets and mechanism are still unclear. Here, catalpol's antidepressant-like molecular target was diagnosed and confirmed by ZnPP intervention [the antagonist of HO-1, (10 μg/rat), intracerebroventricular] for the first time, and its molecule mechanism network was determined through HO-1 related pathway and molecules in the hippocampus. Results showed that ZnPP significantly abolished catalpol's (10 mg/kg) reversal on depressive-like behaviors of chronic unpredictable mild stress rats, abolished catalpol's up-regulation on the phosphorylation level of extracellular regulated protein kinases (ERK)1/2 and brain-derived neurotrophic factor (BDNF)'s receptor tropomyosin-related kinase B (TrkB), the nuclear expression level of nuclear factor E 2-related factor 2 (Nrf2), the levels of anti-oxidant factors (such as HO-1, SOD, GPX, GST, GSH) and BDNF, and abolished catalpol's down-regulation on the levels of peroxide and neuroinflammation factors [cyclooxygenase-2 (COX-2), induced nitrogen monoxide synthase (iNOS), nitric oxide (NO)]. Thus, HO-1 could serve as an important potential molecular target for catalpol's antidepressant-like process, and the antidepressant-like mechanism of catalpol could at least involve the activation of HO-1 triggering the up-regulation of the ERK1/2/Nrf2/HO-1 pathway-related factors to enhance the anti-oxidant defense, triggering the down-regulation of the COX-2/iNOS/NO pathway-related factors to inhibit neuroinflammation, and triggering the up-regulation of the BDNF/TrkB pathway to enhance neurotrophy.

An overview of the behavioral, neurobiological and morphological effects of topiramate in rats exposed to chronic unpredictable mild stress

The environmental psychological stress causes depressive disorders. Stress causes many neurobiological, neurodegenerative changes in brain. Topiramate (TPM) is used in the treatment of epilepsy and psychiatric diseases. However, there are conflicting findings that TPM disrupts cognitive functions. We aimed to investigate the effects of TPM on depression, anxiety, learning and memory as well as neurobiological, morphological changes in rats exposed to chronic unpredictable mild stress (CUMS). After CUMS was formed by random application of nine mild stressors for 45 days, TPM (at doses of 0.1, 1, 10, 100 mg/kg) was administered for 21 days. Sucrose preference, locomotor activity, forced swimming, elevated plus maze and Morris water maze tests were performed. Corticosterone, BDNF (Brain-derived neurotrophic factor) and glutamate levels and volumes of hippocampus were evaluated. Body weights of the rats were measured. Immobilization time increased in CUMS, CUMS + TPM0.1 in forced swimming test and time spent in platform quadrant increased in Control + TPM1, CUMS, CUMS + TPM0.1, CUMS + TPM1 in Morris water maze test. Control + TPM1 decreased distance to platform in Morris water maze while CUMS + TPM100 increased. Learning is impaired in CUMS + TPM100 while it is improved in Control + TPM1. BDNF levels increased in CUMS and glutamate levels increased in CUMS, CUMS + TPM10. Body weight decreased in CUMS, CUMS + TPM0.1, CUMS + TPM1, CUMS + TPM100. Hippocampus volumes increased in CUMS. In conclusion, CUMS improved cognition and this finding was supported by the increase of BDNF levels and volume of hippocampus. TPM 1 mg/kg improved cognition in non-stressed rats. TPM 0.1 and 1 mg/kg improved while TPM 100 mg/kg impaired memory in rats exposed to stress.

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.

Nutritional supplement drink reduces inflammation and postoperative depression in patients after off-pump coronary artery bypass surgery

BACKGROUND

Coronary artery bypass grafting is a surgical treatment for ischemic heart disease. Although development in surgical technique and improvement of perioperative management reduced the postoperative complications, some patients still delayed in progress of postoperative rehabilitation. In this study, we aimed to investigate the effect of daily intake of an herbal medicine-containing drink for rehabilitation after surgery in patients with ischemic heart disease.

AIM

To investigate the effect of taking an herbal medicine-containing, commercially available drink for postoperative rehabilitation in those patients.

METHODS

Patients who underwent isolated off-pump coronary artery bypass (OPCAB) surgery were divided into two groups depend on the timing of the admission to the hospital: the Yunker (YKR) group, that consumed one bottle of a caffeine-free nutritional supplement drink on a daily basis and the control group (CTL) that underwent regular rehabilitation.

RESULTS

A total of 229 patients (CTL = 130, YKR = 99) were enrolled. No significant differences were observed in the baseline characteristics between the two groups. The YKR group had a significantly increased number of daily steps postoperatively (P < 0.05) and had significantly lower postoperative serum tumor necrosis factor-alpha levels (P < 0.01), while no significant differences were observed in the levels of other inflammatory or stress-related cytokines (interleukin-6, adiponectin, superoxide dismutase, and urine 8-hydroxy-2′-deoxyguanosine) between the two groups. Also, the YKR group showed a significant improvement in the Hospital Anxiety and Depression Score (P < 0.05). Moreover, there were no differences in postoperative complications and the duration of postoperative hospital stay between the two groups.

CONCLUSION

Our results demonstrated that the daily intake of an herbal medicine-containing drink after OPCAB surgery may have beneficial effects on cardiac rehabilitation by reducing inflammation markers and depression.

Catalpol Weakens Depressive-like Behavior in Mice with Streptozotocin-induced Hyperglycemia via PI3K/AKT/Nrf2/HO-1 Signaling Pathway

Depression has huge social risks of high incidence, disability, and suicide. Its prevalence and harm in people with hyperglycemia are 2-3 times higher than in normal people. However, antidepressants with precise curative effects and clear mechanisms for patients with hyperglycemia are currently lacking. Prescriptions containing Rehmannia glutinosa, a traditional medicinal herb with a wide range of nutritional and medicinal values, are often used as antidepressants in Chinese clinical medicine. Catalpol is one of the main effective compounds of R. glutinosa, with multiple biological activities such as hypoglycemia. Here, the antidepressant effect of catalpol on the pathological state of streptozotocin (STZ)-induced hyperglycemia and the underlying molecular mechanisms were analyzed. Results showed that administering catalpol orally to hyperglycemic mice for 21 consecutive days significantly reversed the abnormalities in tail suspension, forced swimming, and open field tests. Catalpol also reversed the abnormal phosphorylation of phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT) and the abnormal levels of nuclear factor erythroid 2-related factor 2 (Nrf2) protein, heme oxygenase-1 (HO-1), and antioxidants, including superoxide dismutase, glutathione peroxidase, glutathione-s transferase, reduced glutathione, and malondialdehyde in the hippocampus and frontal cortex of STZ-induced hyperglycemic mice. Thus, catalpol attenuates depressive-like behavior in pathological hyperglycemic state, and the antidepressant mechanism could at least be partly attributed to the upregulation of the PI3K/AKT/Nrf2/HO-1 signaling pathway in both brain regions, thus restoring the balance between oxidative and antioxidant damage. These data expanded the scientific understanding of catalpol and provided preclinical experimental evidence for its application.

Antidepressant mechanism of catalpol: Involvement of the PI3K/Akt/Nrf2/HO-1 signaling pathway in rat hippocampus

Catalpol is a major compound in Rehmanniae Radix with outstanding medicinal and nutritional values. Our previous studies have demonstrated catalpol's antidepressant effect, but its mechanisms remain unclear. This study aimed to explore the antidepressant mechanisms of catalpol via the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/nuclear factor E2-related factor 2(Nrf2)/heme oxygenase-1 (HO-1) pathway. Results demonstrated that chronic unpredictable mild stress (CUMS) for 5 consecutive weeks caused significant decreases in the sucrose preference and the horizontal and vertical scores of open-field test, as well as a significant increase in the swimming-immobility time of rats; catalpol administration significantly reversed the abnormality of these indicators. Further real-time fluorescent quantitative polymerase chain reaction and Western blotting results together showed that CUMS significantly downregulated the expression levels of hippocampal genes and proteins, including PI3K, Akt, Nrf2, HO-1, tropomyosin-related kinase B (TrkB), and brain-derived neurotrophic factor; catalpol administration significantly reversed the abnormal expression of these genes and proteins. CUMS also caused a significant decrease in the hippocampal superoxide dismutase, catalase, glutathione peroxidase, glutathione-s transferase, and reduced glutathione levels, as well as a significant increase in thiobarbituric acid reactive substances level in rats; catalpol administration significantly reversed the abnormality of these indicators. Taken together, this study confirmed for the first time that the antidepressant effect of catalpol on CUMS-induced depression involved the upregulation of the PI3K/Akt/Nrf2/HO-1 signaling pathway, thereby improving the hippocampal neurotrophic, neuroprotective, and antioxidant levels. The PI3K/Akt/Nrf2/HO-1 pathway-related molecules may serve as potential new biomarkers and candidate molecular targets for catalpol's antidepressant effects.

Catalpol enhanced physical exercise-mediated brain functional improvement in post-traumatic stress disorder model via promoting adult hippocampal neurogenesis

Post-traumatic stress disorder (PTSD) is a serious psychiatric disorder characterized by hyper-response to environmental cues as well as the associated depressive and cognitive dysfunctions. According to the key roles of hippocampus for cognitive and emotional regulation, improving hippocampal functions, particularly hippocampal neural plasticity, is the necessary pathway to attenuate the core symptoms of PTSD. The effects of the alternative therapies such as exercise and natural compounds to reduce PTSD symptoms and promote adult hippocampal neurogenesis have been widely demonstrated. However, what is the effect of combining the exercise with traditional Chinese medical compounds remains unknown. In current study, we evaluated the effects of catalpol, which showed the pro-neurogenic effects in previous report, in regulating exercise-mediated PTSD therapeutic effects. With behavioral tests, we found that catalpol treatment promoted the effects of exercise to reduce the response of mice to dangerous cues, and simultaneously enhanced the antidepressant and cognitive protection effects. Moreover, by immunofluorescence we identified that catalpol promoted exercise-mediated hippocampal neurogenesis by enhancing the neural differentiation and mature neuronal survive. We further found that the promote effects of catalpol to exercise-induced environmental hyper-response, antidepressant effects and cognitive protective effects were all compromised by blocking neurogenesis with temozolomide (TMZ). This result indicates that hippocampal neurogenesis is prerequisite for catalpol to promote exercise-mediated brain functional improvement in PTSD model. In conclusion, our research identified the new function of natural compounds catalpol to promote the exercise-mediated brain functional changes in PTSD model, which depend on its effect promoting adult hippocampal neurogenesis.

Therapeutic potential of catalpol and geniposide in Alzheimer's and Parkinson's diseases: A snapshot of their underlying mechanisms

Rehmannia glutinosa, the fresh or dried root of Rehmannia glutinosa (Gaertn.) Libosch. ex Fisch. & Mey., and Gardenia, the fruit of Gardenia jasminoides Ellis from Rubiaceae, both are famous traditional Chinese medicines that have been traditionally used in China. Catalpol and geniposide, as two kinds of iridoid glycosides with high activities, are the main bioactive components in Rehmannia glutinosa and Gardenia jasminoides Ellis, respectively. Over the past few decades, catalpol and geniposide have been widely studied for their therapeutic effects. The preclinical experiments demonstrated that they possessed significant neuroprotective activities against Alzheimer's disease, Parkinson's disease, stroke, and depression, etc. In this paper, the pharmacological effects and mechanisms of catalpol and geniposide on Alzheimer's disease and Parkinson's disease from 2005 to now were systematically summarized and comprehensively analyzed. At the same time, the pharmacokinetic characteristics of the analyzed compounds were also described, hoping to provide some enlightenment for the design, research, and development of iridoid glycosides.

Catalpol ameliorates depressive-like behaviors in CUMS mice via oxidative stress-mediated NLRP3 inflammasome and neuroinflammation

The purpose of the present study was to investigate whether catalpol exhibited neuroprotective effects in chronic unpredictable mild stress (CUMS) mice through oxidative stress-mediated nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin-domain-containing 3 (NLRP3) inflammasome and neuroinflammation. Deficits in behavioral tests, including open field test (OFT), forced swim test (FST), and elevated plus-maze test (EPM), were ameliorated following catalpol administration. To study the potential mechanism, western blots, quantitative real-time PCR (qRT-PCR) analysis and immunofluorescence imaging were performed on the hippocampus samples. We found that the defects of behavioral tests induced by CUMS could be reversed by the absence of NLRP3 and NLRP3 inflammasome might be involved in the antidepressant effects of catalpol on CUMS mice. Similar to the NLRP3 inflammasome, the expression of interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), and inducible nitride oxide synthase (iNOS) were increased after CUMS. The current study demonstrated that catalpol possessed anti-inflammatory effect on CUMS mice and inhibited microglial polarization to the M1 phenotype. In addition, the activity of mitochondrial oxidative stress might be involved in the NLRP3 activation, which was proved by the downregulation of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), and cleaved IL-1β, after the administration of mitochondrion-targeted antioxidant peptide SS31. Taken together, we provided evidence that catalpol exhibited antidepressive effects on CUMS mice possibly via the oxidative stress-mediated regulation of NLRP3 and neuroinflammation.

Effect and Mechanism of Catalpol on Remyelination via Regulation of the NOTCH1 Signaling Pathway

Promoting the differentiation of oligodendrocyte precursor cells (OPCs) is important for fostering remyelination in multiple sclerosis. Catalpol has the potential to promote remyelination and exert neuroprotective effects, but its specific mechanism is still unclear. Recent studies have shown that the NOTCH1 signaling pathway is involved in mediating OPC proliferation and differentiation. In this study, we elucidated that catalpol promoted OPC differentiation in vivo and vitro and explored the regulatory role of catalpol in specific biomolecular processes. Following catalpol administration, better and faster recovery of body weight and motor balance was observed in mice with cuprizone (CPZ)-induced demyelination. Luxol fast blue staining (LFB) and transmission electron microscopy (TEM) showed that catalpol increased the myelinated area and improved myelin ultrastructure in the corpus callosum in demyelinated mice. In addition, catalpol enhanced the expression of CNPase and MBP, indicating that it increased OPC differentiation. Additionally, catalpol downregulated the expression of NOTCH1 signaling pathway-related molecules, such as JAGGED1, NOTCH1, NICD1, RBPJ, HES5, and HES1. We further demonstrated that in vitro, catalpol enhanced the differentiation of OPCs into OLs and inhibited NOTCH1 signaling pathway activity. Our data suggested that catalpol may promote OPC differentiation and remyelination through modulation of the NOTCH1 pathway. This study provides new insight into the mechanism of action of catalpol in the treatment of multiple sclerosis.

Roflumilast Ameliorates Isoflurane-Induced Inflammation in Astrocytes via the CREB/BDNF Signaling Pathway

Background and purpose: Astrocyte-mediated neuroinflammation plays an important role in anesthetic isoflurane-induced cognitive impairment. Roflumilast, a selective inhibitor of phosphodiesterase-4 (PDE-4) used for the treatment of chronic obstructive pulmonary disease (COPD), has displayed a wide range of anti-inflammatory capacity in different types of cells and tissues. In the current study, we aimed to investigate whether roflumilast possesses a protective effect against isoflurane-induced insults in mouse primary astrocytes. Methods: Primary astrocytes were isolated from the cerebral cortices of immature rats. The production of NO was determined using DAF-FM DA staining assay. QRT-PCR and western blot were used to evaluate the expression levels of iNOS, COX-2, and BDNF in the astrocytes treated with different therapies. The gene expressions and concentrations of IL-6 and MCP-1 released by the astrocytes were detected using qRT-PCR and ELISA, respectively. The expression levels of phosphorylated CREB and PGE₂ were determined using western blot and ELISA, respectively. H89 was introduced to evaluate the function of CREB. Recombinant human BDNF and ANA-12 were used to verify the role of BDNF. Results: The upregulated iNOS, excessive production of NO, IL-6, and MCP-1, and activated COX-2/PGE₂ signaling pathways in the astrocytes induced by isoflurane were significantly reversed by the introduction of roflumilast, in a dose-dependent manner. Subsequently, we found that BDNF could be upregulated by roflumilast, which was verified to be related to the activation of CREB and blocked by H89 (a CREB inhibitor). In addition, the COX-2/PGE₂ signaling pathway activated by isoflurane can be inactivated by recombinant human BDNF. Finally, the regulatory effect of roflumilast against the isoflurane-activated COX-2/PGE₂ signaling pathway was significantly blocked by ANA-12, which is a BDNF inhibitor. Conclusion: Roflumilast might ameliorate isoflurane-induced inflammation in astrocytes via the CREB/BDNF signaling pathway.

Herba Cistanche (Rou Cong Rong): A Review of Its Phytochemistry and Pharmacology

Herba Cistanche, known as Rou Cong Rong in Chinese, is a very valuable Chinese herbal medicine that has been recorded in the Chinese Pharmacopoeia. Rou Cong Rong has been extensively used in clinical practice in traditional herbal formulations and has also been widely used as a health food supplement for a long time in Asian countries such as China and Japan. There are many bioactive compounds in Rou Cong Rong, the most important of which are phenylethanoid glycosides. This article summarizes the up-to-date information regarding the phytochemistry, pharmacology, processing, toxicity and safety of Rou Cong Rong to reveal its pharmacodynamic basis and potential therapeutic effects, which could be of great value for its use in future research.

Relationship between depression and olfactory sensory function: a review

Links between olfactory sensory function and effect have been well established. A robust literature exists in both humans and animals showing that disrupting olfaction sensory function can elicit disordered mood state, including serve as a model of depression. Despite this, considerably less is known regarding the directionality and neural basis of this relationship, e.g. whether disruptions in sensory function precede and contribute to altered mood or if altered mood state precipitates changes in olfactory perception. Further, the neural basis of altered olfactory function in depression remains unclear. In conjunction with clinical studies, animal models represent a valuable tool to understand the relationship between altered mood and olfactory sensory function. Here, we review the relevant literature assessing olfactory performance in depression in humans and in rodent models of depressive-like behavioral states. Rodents allow for detailed characterization of alterations in olfactory perception, manipulation of experiential events that elicit depressive-like phenotypes, and allow for interrogation of potential predictive markers of disease and the cellular basis of olfactory impairments associated with depressive-like phenotypes. We synthesize these findings to identify paths forward to investigate and understand the complex interplay between depression and olfactory sensory function.

Traditional Chinese Medicine Jiuwei Zhenxin Granules in Treating Depression: An Overview

Depression is known as "Yu Zheng" in traditional Chinese medicine (TCM). Jiuwei Zhenxin granules (JZG) is a type of TCM. According to TCM theory, it nourishes the heart and spleen, tonifies Qi, and tranquilizes the spirit, and may also has effects in the treatment of depression. Here, we systematically reviewed recent basic and clinical experimental studies of JZG and depression, including studies of the pharmacological mechanisms, active ingredients, and clinical applications of JZG in depression treatment. This review will deepen our understanding of the pharmacological mechanisms, drug interactions, and clinical applications of TCM prescriptions and provide a basis for the development of new drugs in the treatment of depression.

Multiple Biological Effects of an Iridoid Glucoside, Catalpol and Its Underlying Molecular Mechanisms

Catalpol, an iridoid glucoside, is widely distributed in many plant families and is primarily obtained from the root of Rehmanniaglutinosa Libosch. Rehmanniaglutinosa is a plant very commonly used in Chinese and Korean traditional medicine for various disorders, including diabetes mellitus, neuronal disorders, and inflammation. Catalpol has been studied extensively for its biological properties both in vitro and in vivo. This review aims to appraise the biological effects of catalpol and their underlying mechanisms. An extensive literature search was conducted using the keyword "Catalpol" in the public domains of Google scholar, PubMed, and Scifinder. Catalpol exhibits anti-diabetic, cardiovascular protective, neuroprotective, anticancer, hepatoprotective, anti-inflammatory, and anti-oxidant effects in experimental studies. Anti-inflammatory and antioxidant properties are mostly related for its biological effect. However, some specific mechanisms are also elucidated. Elevated serotonin and BDNF level by catalpol significantly protect against depression and neurodegeneration. Catalpol demonstrated an increased mitochondrial biogenesis and activation of PI3K/Akt pathway for insulin sensitizing effect. Further, its cardiovascular protective effect was linked to PI3K/Akt, apelin/APJ and Jak-Stat pathway. Catalpol produced a significant reduction in cell proliferation and an increase in apoptosis in different cancer conditions. Overall, catalpol demonstrated multiple biological effects due to its numerous mechanisms including anti-inflammatory and antioxidant effects.

Calotropis procera attenuates chronic unpredictable mild stress-induced depression in experimental animals

Calotropis procera (CP; Apocynaceae) is reported to have several neuroprotective activities however it's anti-depressant activity yet to be established. Therefore, the present study was proposed to evaluate the anti-depressant activity of the standardized ethanolic extract of CP (ECP) in chronic unpredictable mild stress (CUMS) paradigm exposed male rats. Animals were exposed to CUMS from day-1 (D-1) to D-28 except control group animals of the experimental schedule. ECP (50, 100 and 200 mg/kg, p.o.) and Imipramin (15.0 mg/kg, p.o.) were administered for seven consecutive days after CUMS paradigm. On D-35, ECP (200 mg/kg) significantly attenuated immobility period of the animals in both forced-swim and tail suspension and improved behavioural parameters in open-field and anhedonia in sucrose feeding tests. ECP (200 mg/kg) attenuated CUMS-induced hyperactivity of HPA-axis function. Further, ECP (200 mg/kg) mitigated CUMS-induced decrease in serotonin (5-HT), increase in 5-hydroxy indole acetic acid (5-HIAA) and increase in the ratio of 5-HIAA/5-HT in hippocampus and pre-frontal cortex. The CUMS-induced decrease in the level of expression of BDNF was significantly reversed with ECP (200 mg/kg) treatment. Moreover, ECP (200 mg/kg) significantly reduced the CUMS-induced decrease in the mitochondrial function and integrity in terms of level of formazan formed and intensity of tetramethyl rhodamine methylester dye in both the brain regions respectively. Therefore, ECP (200 mg/kg) mitigates CUMS-induced alterations in the behaviours, HPA-axis function, serotonergic activity, neurogenesis and mitochondrial function in the rodents. Thus, it can be assumed that ECP could be a potential alternative candidate in the management of depression.

Ameliorative effects of Radix rehmanniae extract on the anxiety- and depression-like symptoms in ovariectomized mice: A behavioral and molecular study

BACKGROUND

Menopause is closely associated with the risk of anxiety and depression in a woman's life. Despite the numerous reports on the effects of Radix rehmanniae extract (RRE) on various types of depression, there are few studies exploring the effects of RRE on the menopausal anxiety and depression.

PURPOSE

To investigate whether RRE could alleviate the menopausal anxiety and depression in ovariectomized (OVX) mice submitted to chronic unpredictable mild stress (CUMS).

METHODS

OVX mice were treated with 2.6 g/kg RRE for 5 weeks. After a series of behavior tests, serum, uterus, and brain tissues were collected for the measurement of neurotransmitters and their related biomarkers, neurotrophins, and estrogen receptor α (ERα) and β (ERβ).

RESULTS

RRE showed antidepressant and anxiolytic effects through these behavior tests, but had no effects on the OVX-induced weight gains, uterine shrinkage and drop of serum estrogen level. RRE restored the levels of serotonin (5-HT), dopamine (DA) and its metabolite 3,4-dihydroxyphenylacetic acid (DOPAC), Glutamate (Glu), gamma-Aminobutyric acid (GABA) and their related biomarkers in different brain regions. RRE also reversed OVX-induced decrease in the expression levels of neurotrophins in uterus and brain regions except for uterine nerve growth factor (NGF). Moreover, RRE restored and even enhanced ERβ expression levels in uterus and brain without affecting uterine, hippocampal and cortical ERα.

CONCLUSION

This study demonstrated the antidepressant and anxiolytic effects of RRE in OVX mice, which were possibly mediated via their modulation of brain neurotransmitters, and regulation of neurotrophins and activation of ERβ.

Botanicals as modulators of depression and mechanisms involved

Depression is the most disastrous mood disorder affecting the health of individuals. Conventional treatments with chemical compounds for depression have limitations, while herbal medicine has unique therapeutic effects. This paper introduces the pharmacological basis and biological mechanisms underlying the botanical antidepressants over the past 5 years. Based upon the specific therapeutic targets or mechanisms, we analyzed the pathological roles of monoamine neurotransmitters, the hypothalamic-pituitary-adrenal axis, inflammation, oxidative stress, synaptic plasticity performed in antidepressant of the botanicals. In addition, gut flora and neurogenesis were also preferentially discussed as treatment approaches. Based on the complex pathogenesis of depression, we suggested that mixed use of botanicals, namely prescription would be more suitable for treatment of depression. In addition, neural circuit affected by botanicals or active components should also attract attention as the botanicals have potential to be developed into fast-acting antidepressants. Finally, gut flora might be a new systemic target for the treatment of depression by botanicals. This review would strength botanical medicine as the antidepressant and also provides an overview of the potential mechanisms involved.

Methanol stem bark extract of Adansonia digitata ameliorates chronic unpredictable mild stress-induced depression-like behavior: Involvement of the HPA axis, BDNF, and stress biomarkers pathways

Background Adansonia digitata L. (Malvaceae) is used locally in the management of depressive illnesses, and its antidepressant-like effect has been previously reported. The present study was aimed at determining the effect of the methanol extract of the stem bark of A. digitata (MEAD) on chronic unpredictable mild stress (CUMS) and the possible mechanism responsible for its antidepressant activity. Methods Acute toxicity of MEAD was determined using the OECD guideline 420. The CUMS model was used to induce depression, and behavioral tests such as sucrose preference test (SPT), open field test (OFT), novel-object recognition test (NORT), and tail suspension test (TST) were carried out in mice. The concentrations of plasma cortisol and brain-derived neurotrophic factor (BDNF) protein in the brain were assessed using enzyme-linked immunosorbent assay kits. The levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were assessed using colorimetric methods. Results The LD50 was established to be ≥5000 mg/kg. On CUMS-induced depression, MEAD significantly (p ≤ 0.05) and dose dependently reversed the weight loss, increased the line-crossing activity in OFT, increased sucrose consumption in SPT, decreased the duration of immobility in TST, and increased the novelty exploration time in NORT. The MEAD extract significantly (p ≤ 0.05) and dose dependently increased the levels of BDNF, decreased the levels of plasma cortisol, increased the levels of total SOD activity, and decreased the levels of plasma MDA. Conclusion Our findings show that MEAD ameliorates CUMS-induced depressive-like behavior and its effect is possibly mediated via the neuroendocrine, neurotrophic, and oxidative stress pathways.

Catalpol Exerts an Anti-Epilepticus Effect, Possibly by Regulating the Nrf2-Keap1-ARE Signaling Pathway

Background

Status epilepticus (SE) is a refractory neurological disease with high mortality and morbidity rates. SE can be induced by numerous factors, including oxidative stress. Catalpol has several biological activities, including regulating the oxidative stress response. However, the role of catapol in SE has not been fully elucidated.

Material/Methods

Thirty Wistar rats were randomly and equally divided into 3 groups: a control group, an SE group established by LiCl-pilocarpine intraperitoneal injection, and an SE+catalpol group established administering catalpol to SE rats. Epileptic seizure level and after-discharge duration (ADD) were analyzed. Cognitive function was assessed by Morris water maze. Myeloperoxidase (MPO) and superoxide dismutase (SOD) activities were tested. Keap1 and ARE mRNA expressions were detected by real-time PCR. Nrf2 protein expression was determined by Western blot.

Results

Catalpol significantly decreased epileptic seizure level, extended ADD, and improved cognitive function compared with the SE group (P<0.05). MPO was increased, SOD was reduced, Keap1 mRNA was upregulated, and Nrf2 protein and ARE mRNA were reduced in the SE group compared with the control group (P<0.05). Catalpol markedly decreased MPO, enhanced SOD activity, decreased Keap1 mRNA level, and elevated Nrf2 protein and ARE mRNA expressions compared with the SE group (P<0.05).

Conclusions

Catalpol plays an anti-epileptic role and improves cognitive function by regulating the Nrf2-Keap1-ARE signaling pathway to inhibit oxidative stress response.

Mesolimbic dopamine system and its modulation by vitamin D in a chronic mild stress model of depression in the rat

Depression, a common mood disorder, involves anhedonia and defects in reward circuits and mesolimbic dopamine transmission in the striatum and nucleus accumbens (NAc). Active vitamin-D, (1,25-(OH)₂ vitamin-D3), exerts protective and regulatory effects on the brain dopamine system. In this study, key depression-like symptoms were induced in rats by chronic mild-stress (CMS) and the comparative effect of treatment with 1,25-(OH)₂ vitamin-D3 (5, 10 μg/kg, or vehicle; i.p., twice weekly) or fluoxetine (5 mg/kg or vehicle, i.p., daily) on anhedonic behavior, locomotor activity and anxiety-like behavior was examined using sucrose preference test (SPT), open field test (OFT) and novel object exploration test (NOT), respectively. We also measured serum corticosterone levels and dopamine transporter-immunoreactivity (DAT-ir) levels in NAc shell and core. CMS exposure for 3 weeks was followed by a SPT and thereafter CMS was continued for 5 weeks, along with vitamin-D or fluoxetine treatment and further testing, which was concluded with another SPT. Vitamin-D treatment enhanced sucrose preference (P < 0.01; an hedonic effect) and increased object exploration (P < 0.01) in CMS rats. CMS significantly reduced the level of DAT-ir in NAc (P < 0.0001). Vitamin-D treatment restored/increased DAT-ir levels (P < 0.0001) in CMS rat NAc (core/ shell), compared to levels in fluoxetine treated and non-treated CMS rats. Vitamin-D did not alter locomotor activity or produce an anxiolytic effect in the OFT. These data suggest that similar to the antidepressant, fluoxetine, regular vitamin-D treatment can improve 'anhedonia-like symptoms' in rats subjected to CMS, probably by regulating the effect of dopamine-related actions in the NAc.

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.

Changes in synaptic plasticity are associated with electroconvulsive shock-induced learning and memory impairment in rats with depression-like behavior

BACKGROUND

Accompanied with the effective antidepressant effect, electroconvulsive shock (ECS) can induce cognitive impairment, but the mechanism is unclear. Synaptic plasticity is the fundamental mechanism of learning and memory. This study aimed to investigate the effect of ECS on synaptic plasticity changes in rats with depression-like behavior.

METHODS

Chronic unpredictable mild stress procedure was conducted to establish a model of depression-like behavior. Rats were randomly divided into the following three groups: control group with healthy rats (group C), rats with depression-like behavior (group D), and rats with depression-like behavior undergoing ECS (group DE). Depression-like behavior and spatial learning and memory function were assessed by sucrose preference test and Morris water test, respectively. Synaptic plasticity changes in long-term potentiation (LTP), long-term depression (LTD), depotentiation, and post-tetanic potentiation (PTP) were tested by electrophysiological experiment.

RESULTS

ECS could exert antidepressant effect and also induced spatial learning and memory impairment in rats with depression-like behavior. And, data on electrophysiological experiment showed that ECS induced lower magnitude of LTP, higher magnitude of LTD, higher magnitude of depotentiation, and lower magnitude of PTP.

CONCLUSION

ECS-induced learning and memory impairment may be attributed to postsynaptic mechanism of LTP impairment, LTD and depotentiation enhancement, and presynaptic mechanism of PTP impairment.

Honokiol Exerts Antidepressant Effects in Rats Exposed to Chronic Unpredictable Mild Stress by Regulating Brain Derived Neurotrophic Factor Level and Hypothalamus-Pituitary-Adrenal Axis Activity

Honokiol (HNK), the main active component of Magnolia officinalis, has shown a variety of pharmacological activities. In the present study, we measured the antidepressant-like effects of HNK in a rat model of chronic unpredictable mild stress (CUMS) and explored its possible mechanisms. The antidepressant-like effects of HNK were assessed in rats by an open field test (OFT), sucrose preference test (SPT) and forced swimming test (FST). Then, serum levels of corticotrophin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and corticosterone (CORT) and hippocampal brain-derived neurotrophic factor (BDNF) and glucocorticoid receptor α (GRα) levels were assessed to explore the possible mechanisms. We identified that HNK treatment (2, 4, and 8 mg/kg) alleviated the CUMS-induced behavioural deficits. Treatment with HNK also normalized the CUMS-induced hyperactivity of the limbic hypothalamic-pituitary-adrenal (HPA) axis, as indicated by reduced CRH, ACTH and CORT serum levels. In addition, HNK increased the expression of GRα (mRNA and protein) and BDNF (mRNA and protein) in the hippocampus. These data confirmed the antidepressant-like effects of HNK, which may be related to its normalizing the function of the HPA axis and increasing the BDNF level in the hippocampus.

Antidepressant-like effects of embelin and its possible mechanisms of action in chronic unpredictable stress-induced mice

Objectives Embelin, a principal active constituent of embelin ribes burm, has good therapeutic effects on various diseases. To explore the effects and underlying mechanisms of embelin on depression, we made a preliminary study to clarify this issue. Methods We first used chronic unpredictable stress (CUS) to construct the model of depression in mice. Then, we determined the effects of embelin on CUS-induced behavioral dysfunction using open field test, sucrose preference test, tail suspension test and forced swimming test. Furthermore, we used the biological experiments to evaluate the changes of brain-derived neurotrophic factor (BDNF), oxidative stress, neuronal inflammation and the hypothalamic pituitary adrenal (HPA) axis after embelin treatment. Results The behavioral tests indicated embelin indeed had efficient antidepressant effects. Moreover, enhanced BDNF expression, decreased oxidative stress markers (TBARS, nitric oxide) activities, elevated antioxidants (total thiol, catalase) expression, decreased pro-inflammatory cytokines (IL-6, TNF-α, IL-1β and COX-2) expression and normalized the HPA axis activity were found after embelin treatment in CUS-induced mice. Hence, the results of biological experiments confirmed the antidepressant-like effects of embelin. Discussion These results indicated that embelin can effectively suppress CUS-induced depressive-like behaviors through increasing BDNF expression, preventing brain from oxidative stress and neuronal inflammation, and normalizing the HPA activity.

Exercise-Mediated Neurogenesis in the Hippocampus via BDNF

Exercise is known to have numerous neuroprotective and cognitive benefits, especially pertaining to memory and learning related processes. One potential link connecting them is exercise-mediated hippocampal neurogenesis, in which new neurons are generated and incorporated into hippocampal circuits. The present review synthesizes the extant literature detailing the relationship between exercise and hippocampal neurogenesis, and identifies a key molecule mediating this process, brain-derived neurotrophic factor (BDNF). As a member of the neurotrophin family, BDNF regulates many of the processes within neurogenesis, such as differentiation and survival. Although much more is known about the direct role that exercise and BDNF have on hippocampal neurogenesis in rodents, their corresponding cognitive benefits in humans will also be discussed. Specifically, what is known about exercise-mediated hippocampal neurogenesis will be presented as it relates to BDNF to highlight the critical role that it plays. Due to the inaccessibility of the human brain, much less is known about the role BDNF plays in human hippocampal neurogenesis. Limitations and future areas of research with regards to human neurogenesis will thus be discussed, including indirect measures of neurogenesis and single nucleotide polymorphisms within the BDNF gene.

Antidepressant and pro-neurogenic effects of agmatine in a mouse model of stress induced by chronic exposure to corticosterone

Agmatine is an endogenous neuromodulator that has been shown to have beneficial effects in the central nervous system, including antidepressant-like effects in animals. In this study, we investigated the ability of agmatine (0.1mg/kg, p.o.) and the conventional antidepressant fluoxetine (10mg/kg, p.o.) to reverse the behavioral effects and morphological alterations in the hippocampus of mice exposed to chronic corticosterone (20mg/kg, p.o.) treatment for a period of 21days as a model of stress and depressive-like behaviors. Chronic corticosterone treatment increased the immobility time in the tail suspension test (TST), but did not cause anhedonic-like and anxiety-related behaviors, as assessed with the splash test and the open field test (OFT), respectively. Of note, the depressive-like behaviors induced by corticosterone were accompanied by a decrease in hippocampal cell proliferation, although no changes in hippocampal neuronal differentiation were observed. Our findings provide evidence that, similarly to fluoxetine, agmatine was able to reverse the corticosterone-induced depressive-like behaviors in the TST as well as the deficits in hippocampal cell proliferation. Additionally, fluoxetine but not agmatine, increased hippocampal differentiation. Agmatine, similar to fluoxetine, was capable of increasing both dendritic arborization and length in the entire dentate hippocampus, an effect more evident in the ventral portion of the hippocampus, as assessed with the modified Sholl analysis. Altogether, our results suggest that the increase in hippocampal proliferation induced by agmatine may contribute, at least in part, to the antidepressant-like response of this compound in this mouse model of stress induced by chronic exposure to corticosterone.

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.

Protective effect of catalpol on nicotine‑induced injury of alveolar bone and associated underlying mechanisms

Smoking is an important factor that causes periodontitis, which manifests as alveolar bone injury and absorption, and has a high incidence and unfavorable treatment efficacy. Nicotine causes ischemia and inflammation of the periodontium and inhibits the mineralization of alveolar bones. Previous studies have revealed the anti‑tumor biological activities of catalpol, in addition to neuroprotection and anti‑inflammation. The present study therefore investigated the underlying protective mechanism of catalpol in alveolar bone injury. A total of 24 Wistar rats were infused with nicotine (0.7 mg/kg for 30 days), followed by subcutaneous injection of catalpol (2 µg/kg for 14 days). The loss of alveolar bone was examined, and bone alkaline phosphatase (AP) and osteocalcin levels were examined by ELISA. The expression of tumor necrosis factor (TNF)‑α and cyclooxygenase‑2 (COX‑2) was quantified by reverse transcription‑quantitative polymerase chain reaction analysis and western blotting. Treatment with nicotine decreased AP and osteocalcin levels, increased TNF‑α and COX‑2 expression levels, and led to alveolar bone loss compared with the control group. Catalpol decreased bone loss, increased AP and osteocalcin, and decreased TNF‑α and COX‑2 expression compared with the nicotine treatment group. Catalpol may alleviate nicotine‑induced injury and alveolar bone loss via inhibition of inflammatory factors, and facilitate the mineralization of alveolar bones.

Effects of α2A Adrenoceptors on Norepinephrine Secretion from the Locus Coeruleus during Chronic Stress-Induced Depression

Chronic stressors can often lead to the development of psychological disorders, such as depression and anxiety. The locus coeruleus (LC) is a stress sensitive brain region located in the pons, with noradrenergic neurons that project to the hypothalamus, especially the paraventricular nucleus (PVN) of the hypothalamus. The purpose of this paper is to better understand how alpha 2A-adrenoceptors (α_2A-ARs) and LC-hypothalamus noradrenergic system participate in the pathophysiological mechanism of depression. In vivo norepinephrine (NE) release in the PVN triggered by electrical stimulation in the LC was detected with carbon fiber electrodes in depression model of rats induced by chronic unpredictable mild stress (CUMS). Also, the extracellular level of NE in the PVN was measured by microdialysis in vivo without any stimulation in the LC. The alpha 2-adrenoceptor (α₂-AR) antagonist yohimbine and α_2A-ARs antagonist BRL-44408 maleate were systemically administered to rats to determine the effects of α_2A-ARs on NE release in the PVN. The peak value of elicited NE release signals in the PVN induced by electrical stimulation in the LC in the CUMS rats were lower than that in the control rats. The extracellular levels of NE in the PVN of the CUMS rats were significantly less than that of the control rats. Intraperitoneal injection of yohimbine or BRL-44408 maleate significantly potentiated NE release in the PVN of the CUMS rats. The CUMS significantly increased protein expression levels of α_2A-AR in the hypothalamus, and BRL-44408 maleate significantly reversed the increase of α_2A-AR protein expression levels in the CUMS rats. Our results suggest that the CUMS could significantly facilitate the effect of α2-adrenoceptor-mediated presynaptic inhibition and decrease the release of NE in the PVN from LC. Blockade of the inhibitory action of excessive α2A-adrenergic receptors in the CUMS rats could increase the level of NE in the PVN, which is effective in the treatment of depressive disorders.

Lyophilized Powder of Catalpol and Puerarin Protected Cerebral Vessels from Ischemia by Its Anti-apoptosis on Endothelial Cells

Catalpol and puerarin are two monomers of Rehmannia glutinosa and Lobed Kudzuvine Root, which are two herbs commonly used together in ancient prescriptions of traditional Chinese medicine for cerebral ischemia. Our previous study shows that the lyophilized powder of the two monomers improved the outcome of cerebral ischemia excellently in rodents. However, if it protects vessels from ischemia is unknown. The present research studied the protection of lyophilized powder of catalpol and puerarin (CP) on endothelial cells and the relative mechanism in vivo and in vitro. Middle cerebral artery occlusion (MCAO) rats were used to study the improvement of CP on neurological deficiency, regional cerebral blood flow (rCBF), and infarct volume. The morphology of vessels and the apoptosis of brain vascular endothelial cells (BVECs) were observed and detected by immunohistochemistry approaches. To study how CP protected primary BVECs (pBVECs) from ischemic penumbra, oxygen glucose deprivation (OGD)-damaged pBVECs were cultured in the condition of insufficient nutrition and low oxygen which recapitulate the low perfusion of ischemic penumbra. Using the cell model, the mechanism by which CP protected pBVECs was studied by shRNA and pathway inhibitors. CP at the dose of 65.4 mg/kg increased regional cerebral blood flow (rCBF), reduced infarct volume, protected vessel integrity and inhibited endothelial cell apoptosis in vivo. But it only improved rCBF, vessel integrity and BVECs apoptosis at the dose of 32.7 mg/kg. In vitro, the protection of CP on pBVECs was proved to be ERK/HIF-1a- and PI3K/AKT/mTOR/HIF-1a-dependent. This study indicates a possibility of CP being a new drug for cerebral ischemia. Besides, this research provides an alternative cell model for penumbra ECs study.