Ginsenoside Rg1 reverses stress-induced depression-like behaviours and brain-derived neurotrophic factor expression within the prefrontal cortex

Efficacy of ginsenoside Rg1 on rodent models of depression: A systematic review and meta-analysis

RATIONALE

Depression is a prevalent psychiatric disease, and ginsenoside Rg1 is a bioactive compound extracted from the root of Panax ginseng C.A.Mey. To systematically investigate the effectiveness of Rg1 in rodent models of depression and provide evidence-based references for treating depression.

METHODS

Electronic searches for rodent studies were performed from inception to October 2022, e.g., PUBMED and EMBASE. Data extraction and quality evaluation were performed for the references, and meta-analysis was performed on the selected data using Review Manager 5.3.5. The outcomes were analyzed via a random-effect model and presented as mean difference (MD) with 95% confidence intervals (CIs).

RESULTS

A total of 24 studies and 678 animals were included in this meta-analysis. Rg1 remarkably improved depressive-like symptoms of depressed rodents, including the sucrose preference test (25.08, 95% CI: 20.17-30.00, Z = 10.01, P < 0.00001), forced swimming test (MD = -37.69, 95% CI: (-45.18, -30.2); Z = 9.86, P < 0.00001), and the tail suspension test (MD = -22.93, seconds, 95% CI: (-38.49, -7.37); Z = 2.89, P = 0.004).

CONCLUSIONS

The main antidepressant mechanism of Rg1 was concluded to be the neurotransmitter system, oxidant stress system, and inflammation. Conclusively, this study indicated the possible protective and therapeutic effects of Rg1 for treating depression via multiple mechanisms.

Pathogenesis of depression and the potential for traditional Chinese medicine treatment

Depression is a prevalent mental disorder that significantly diminishes quality of life and longevity, ranking as one of the primary causes of disability globally. Contemporary research has explored the potential pathogenesis of depression from various angles, encompassing genetics, neurotransmitter systems, neurotrophic factors, the hypothalamic-pituitary-adrenal axis, inflammation, and intestinal flora, among other contributing factors. In addition, conventional chemical medications are plagued by delayed onset of action, persistent adverse effects, and restricted therapeutic efficacy. In light of these limitations, the therapeutic approach of traditional Chinese medicine (TCM) has gained increasing recognition for its superior effectiveness. Numerous pharmacological and clinical studies have substantiated TCM's capacity to mitigate depressive symptoms through diverse mechanisms. This article attempts to summarize the mechanisms involved in the pathogenesis of depression and to describe the characteristics of herbal medicines (including compounded formulas and active ingredients) for the treatment of depression. It further evaluates their effectiveness by correlating with the multifaceted pathogenesis of depression, thereby furnishing a reference for future research endeavors.

Efficacy of Chinese herbal formula Kai-Xin-San on rodent models of depression: A systematic review and meta-analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Kai-Xin-San (KXS, or Happy Feeling Powder), a typical Chinese herbal prescription, is frequently used for treating depression by the multi-level and multi-target mechanism.

AIM OF THE STUDY

To systematically investigate the efficacy and safety of KXS on depression in preclinic trials.

MATERIALS AND METHODS

We independently searched for preclinical animal studies of KXS on depression from inception to June 28, 2022, using electronic databases, e.g., PUBMED. The measurements were performed to assess the outcomes of behavioral tests.

RESULTS

This systematic review and meta-analysis included twenty-four studies and 608 animals. A remarkable effect of KXS in depression behavioral tests, including sucrose consumption test (SMD: 2.36, 95% CI: (1.81, 2.90); Z = 8.49, P < 0.00001)., forced swimming test (MD = -60.52, 95% CI: (-89.04, -31.99); Z = 4.16, P < 0.0001), rearing times (MD=4.48, 95% CI: (3.39, 5.57); Z = 8.05, P < 0.00001) and crossing times (MD = -33.7, 95% CI: (25.74, 41.67); Z = 8.29, P < 0.00001) in the open field test, showing KXS's excellent efficiency in improving depressive-like symptoms of animals.

CONCLUSIONS

Our meta-analysis showed KXS remarkably relieved animals' depressive-like symptoms, providing evidence that KXS can be a promising drug candidate for depression treatment.

Ginsenoside Rg1, lights up the way for the potential prevention of Alzheimer's disease due to its therapeutic effects on the drug-controllable risk factors of Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine, Shen Nong, BenCao Jing, and Compendium of Materia Medica (Bencao Gangmu), Panax ginseng, and its prescriptions have been used for the treatment of dementia, depression, weight loss, Xiaoke disease (similar to diabetes), and vertigo. All these diseases are associated with the drug-controllable risk factors for Alzheimer's disease (AD), including depression, obesity, diabetes, and hypertension. Ginsenoside Rg1, one of the main active ingredients of P. ginseng and its congener Panax notoginseng, possesses therapeutic potentials against AD and associated diseases. This suggests that ginsenoside Rg1 might have the potential for AD prevention and treatment. Although the anti-AD effects of ginsenoside Rg1 have received more attention, a systematic review of its effects on depression, obesity, diabetes, and hypertension is not available.

AIM OF THE REVIEW

This systematic literature review comprehensively summarized existing literature on the therapeutic potentials of ginsenoside Rg1 in AD prevention for the propose of providing a foundation of future research aimed at enabling the use of such drugs in clinical practice.

METHODS

Information on ginsenoside Rg1 was collected from relevant published articles identified through a literature search in electronic scientific databases (PubMed, Science Direct, and Google Scholar). The keywords used were "Ginsenoside Rg1," "Panax ginseng," "Source," "Alzheimer's disease," "Brain disorders," "Depression," "Obesity," "Diabetes," and "Hypertension."

RESULTS

The monomer ginsenoside Rg1 can be relatively easily obtained and has therapeutic potentials against AD. In vitro and in vivo experiments have demonstrated the therapeutic potentials of ginsenoside Rg1 against the drug-controllable risk factors of AD including depression, obesity, diabetes, and hypertension. Thus, ginsenoside Rg1 alleviates diseases resulting from AD risk factors by regulating multiple targets and pathways.

CONCLUSIONS

Ginsenoside Rg1 has the potentials to prevent AD by alleviating depression, obesity, diabetes, and hypertension.

Ginsenoside-Rg1 synergized with voluntary running exercise protects against glial activation and dysregulation of neuronal plasticity in depression

Depression is a common psychological disease accompanied by mental disorders and somatic symptoms. However, the underlying mechanisms regarding the pathogenesis of depression are still not clear. Neuronal damage resulting from inflammation is considered to be one of the important risk factors for depression. Ginsenoside-Rg1, a sterol extract extracted from ginseng herbs, has been shown to have neuroprotective effects against neurodegenerative diseases. Moreover, running exercise, a simple behavioral therapy, has been recently shown to have antidepressant effects. However, whether these two synergized strategies are more efficient in depression treatment, especially the neural mechanisms underlying this practical and interesting treatment is unknown. In this study, we have shown that ginsenoside-Rg1 synergized with voluntary running exercise exerts more efficiency on suppressing neuroinflammation, up-regulating expression of neurotrophic factors, and synaptic-related proteins, ameliorating neuronal structural damages than that of ginsenoside-Rg1 or voluntary exercise alone, suggesting its better neuroprotective effects. More importantly, the antidepressant-like effect of this synergistic treatment was also significantly better than either of these two treatments. These results suggest that ginsenoside-Rg1, synergized with voluntary running, may have higher efficacy in the treatment of depression through anti-inflammation and the improvement of neuroplasticity. These findings may provide a new perspective for the development of a therapeutic strategy for depression.

Ginsenoside Rg1 in neurological diseases: From bench to bedside

Ginseng has been used in China as a superior medicinal material for thousands of years that can nourish the five internal organs, calm the mind and benefit wisdom. Due to its anti-inflammatory, antioxidant and neuroprotective activities, one of the active components of ginseng, ginsenoside Rg1, has been extensively investigated in the remedy of brain disorders, especially dementia and depression. In this review, we summarized the research progress on the action mechanisms of Rg1 ameliorating depression-like behaviors, including inhibition of hyperfunction of hypothalamic-pituitary-adrenal (HPA) axis, regulation of synaptic plasticity and gut flora. Rg1 may alleviate Alzheimer's disease in the early phase, as well as in the middle-late phases through repairing dendrite, axon and microglia- and astrocyte-related inflammations. We also proposed that Rg1 could regulate memory state (the imbalance of working and aversive memory) caused by distinct stimuli. These laboratory studies would further the clinical trials on Rg1. From the prospective of drug development, we discussed the limitations of the present investigations and proposed our ideas to increase permeability and bioavailability of Rg1. Taken together, Rg1 has the potential to treat neuropsychiatric disorders, but a future in-depth investigation of the mechanisms is still required. In addition, drug development will benefit from the clinical trials in one specific neuropsychiatric disorder.

The clinical application of Chinese herbal medication to depression: A narrative review

Depression severely impairs psychosocial functioning and quality of life, which places a huge burden on patients and their families. However, the physiological mechanism of depression remains unknown. Treatment with existing antidepressant medications is effective in around 50% of patients according to various studies, but is associated with severe side effects including nausea and headaches. Chinese herbal medicine (CHM) has been approved and widely used for depression as an alternative medicine in Chinese culture for decades. It has certain advantages and potential in the prevention and treatment of depression. In this review, we summarize the currently available evidence for the efficacy of CHM for the treatment of depression and physiological diseases comorbid with depression. We further discuss the possible mechanisms of action of CHM and the relationships to our current understanding of depression. The majority of current evidence has suggested that the combined treatment with CHM and mainstream antidepressants improves the response rate and reduces the side effects, while CHM alone could be more effective than placebo. However, the results should be carefully interpreted due to the shortcomings of existing clinical trials and a high risk of bias in meta-analyses. Our review provides a summary of the current applications and understanding of widely used CHMs for depression.

Phytochemicals That Act on Synaptic Plasticity as Potential Prophylaxis against Stress-Induced Depressive Disorder

Depression is a neuropsychiatric disorder associated with persistent stress and disruption of neuronal function. Persistent stress causes neuronal atrophy, including loss of synapses and reduced size of the hippocampus and prefrontal cortex. These alterations are associated with neural dysfunction, including mood disturbances, cognitive impairment, and behavioral changes. Synaptic plasticity is the fundamental function of neural networks in response to various stimuli and acts by reorganizing neuronal structure, function, and connections from the molecular to the behavioral level. In this review, we describe the alterations in synaptic plasticity as underlying pathological mechanisms for depression in animal models and humans. We further elaborate on the significance of phytochemicals as bioactive agents that can positively modulate stress-induced, aberrant synaptic activity. Bioactive agents, including flavonoids, terpenes, saponins, and lignans, have been reported to upregulate brain-derived neurotrophic factor expression and release, suppress neuronal loss, and activate the relevant signaling pathways, including TrkB, ERK, Akt, and mTOR pathways, resulting in increased spine maturation and synaptic numbers in the neuronal cells and in the brains of stressed animals. In clinical trials, phytochemical usage is regarded as safe and well-tolerated for suppressing stress-related parameters in patients with depression. Thus, intake of phytochemicals with safe and active effects on synaptic plasticity may be a strategy for preventing neuronal damage and alleviating depression in a stressful life.

Neuropharmacological Effects of Terpenoids on Preclinical Animal Models of Psychiatric Disorders: A Review

Terpenoids are widely distributed in nature, especially in the plant kingdom, and exhibit diverse pharmacological activities. In recent years, screening has revealed a wide variety of new terpenoids that are active against different psychiatric disorders. This review synthesized the current published preclinical studies of terpenoid use in psychiatric disorders. This review was extensively investigated to provide empirical evidence regarding the neuropharmacological effects of the vast group of terpenoids in translational models of psychiatric disorders, their relevant mechanisms of action, and treatment regimens with evidence of the safety and psychotropic efficacy. Therefore, we utilized nine (9) electronic databases and performed manual searches of each. The relevant data were retrieved from the articles published until present. We used the search terms "terpenoids" or "terpenes" and "psychiatric disorders" ("psychiatric disorders" OR "psychiatric diseases" OR "neuropsychiatric disorders" OR "psychosis" OR "psychiatric symptoms"). The efficacy of terpenoids or biosynthetic compounds in the terpenoid group was demonstrated in preclinical animal studies. Ginsenosides, bacosides, oleanolic acid, asiatic acid, boswellic acid, mono- and diterpenes, and different forms of saponins and triterpenoids were found to be important bioactive compounds in several preclinical studies of psychosis. Taken together, the findings of the present review indicate that natural terpenoids and their derivatives could achieve remarkable success as an alternative therapeutic option for alleviating the core or associated behavioral features of psychiatric disorders.

New Therapeutic Approaches to and Mechanisms of Ginsenoside Rg1 against Neurological Diseases

Neurological diseases, including Parkinson’s disease (PD), Alzheimer’s disease (AD), Huntington’s disease (HD), stroke, cerebral infarction, ischemia-reperfusion injury, depression and, stress, have high incidence and morbidity and often lead to disability. However, there is no particularly effective medication against them. Therefore, finding drugs with a suitable efficacy, low toxicity and manageable effects to improve the quality of life of patients is an urgent problem. Ginsenoside Rg1 (Rg1) is the main active component of ginseng and has a variety of pharmacological effects. In this review, we focused on the therapeutic potential of Rg1 for improving neurological diseases. We introduce the mechanisms of Ginsenoside Rg1 in neurological diseases, including apoptosis, neuroinflammation, the microRNA (miRNA) family, the mitogen-activated protein kinase (MAPK) family, oxidative stress, nuclear factor-κB (NF-κB), and learning and memory of Rg1 in neurological diseases. In addition, Rg1 can also improve neurological diseases through the interaction of different signal pathways. The purpose of this review is to explore more in-depth ideas for the clinical treatment of neurological diseases (including PD, AD, HD, stroke, cerebral infarction, ischemia–reperfusion injury, depression, and stress). Therefore, Rg1 is expected to become a new therapeutic method for the clinical treatment of neurological diseases.

Antidepressant Active Ingredients From Chinese Traditional Herb Panax Notoginseng: A Pharmacological Mechanism Review

Depression is one of the most common mental illnesses in the world and is highly disabling, lethal, and seriously endangers social stability. The side effects of clinical drugs used to treat depression are obvious, and the onset time is longer. Therefore, there is a great demand for antidepressant drugs with better curative effects, fewer side effects, and shorter onset time. Panax notoginseng, a Chinese herbal medication, has been used to treat depression for thousands of years and shown to have a therapeutic effect on depression. This review surveyed PubMed’s most recent 20 years of research on Panax notoginseng’s use for treating depression. We mainly highlight animal model research and outlined the pathways influenced by medicines. We provide a narrative review of recent empirical evidence of the anti-depressive effects of Panax Notoginseng and novel ideas for developing innovative clinical antidepressants with fewer side effects.

Ginsenosides in central nervous system diseases: Pharmacological actions, mechanisms, and therapeutics

The nervous system is one of the most complex physiological systems, and central nervous system diseases (CNSDs) are serious diseases that affect human health. Ginseng (Panax L.), the root of Panax species, are famous Chinese herbs that have been used for various diseases in China, Japan, and Korea since ancient times, and remain a popular natural medicine used worldwide in modern times. Ginsenosides are the main active components of ginseng, and increasing evidence has demonstrated that ginsenosides can prevent CNSDs, including neurodegenerative diseases, memory and cognitive impairment, cerebral ischemia injury, depression, brain glioma, multiple sclerosis, which has been confirmed in numerous studies. Therefore, this review summarizes the potential pathways by which ginsenosides affect the pathogenesis of CNSDs mainly including antioxidant effects, anti-inflammatory effects, anti-apoptotic effects, and nerve protection, which provides novel ideas for the treatment of CNSDs.

Potential Correlation Between Depression-like Behavior and the Mitogen-Activated Protein Kinase Pathway in the Rat Hippocampus Following Spinal Cord Injury

BACKGROUND

Depression induced by spinal cord injury (SCI) has been demonstrated in clinical and experimental studies; it significantly impacts patients' lives and may be associated with changes in the hippocampus. However, the biological mechanisms underlying depression after SCI are unknown. The mitogen-activated protein kinase (MAPK) signaling pathway participates in potential mechanisms of depression; it is unknown whether this pathway plays a role in SCI-induced depression.

METHODS

We applied an animal model of depression induced by SCI, established using an aneurysm clip, to determine whether MAPK activation in the hippocampus is associated with depression-like behavior.

RESULTS

SCI led to depression-like behavior, such as anhedonia in the sucrose preference test, decreased number of crossings in the open field test, decreased body weight, and decreased immobility time in the forced swim test. Western blot analysis further showed that SCI significantly increased the levels of phosphorylated p38 MAPK and cleaved caspase-3 in the hippocampus and inhibited the phosphorylation of extracellular signal-related kinase 1/2 and c-Jun N-terminal kinase 1/2. In addition, there were significant negative correlations between depression-like behavior and phosphorylated extracellular signal-related kinase 1/2 and positive correlations between depression-like behavior and phosphorylated p38 MAPK and cleaved caspase-3.

CONCLUSIONS

These findings suggest that the MAPK pathway in the rat hippocampus may be involved in the pathophysiology of depression induced by SCI.

The effect of ginsenosides on depression in preclinical studies: A systematic review and meta-analysis

BACKGROUND

Many ginsenosides have been shown to be efficacious for major depressive disorder (MDD), which is a highly recurrent disorder, through several preclinical studies. We aimed to review the literature assessing the antidepressant effects of ginsenosides on MDD animal models, to establish systematic scientific evidence in a rigorous manner.

METHODS

We performed a systematic review on the antidepressant effects of ginsenoside evaluated in in vivo studies. We searched for preclinical trials from inception to July 2019 in electronic databases such as Pubmed and Embase. In vivo studies examining the effect of a single ginsenoside on animal models of primary depression were included. Items of each study were evaluated by two independent reviewers. A meta-analysis was conducted to assess behavioral changes induced by ginsenoside Rg1, which was the most studied ginsenoside. Data were pooled using the random-effects models.

RESULTS

A total of 517 studies were identified, and 23 studies were included in the final analysis. They reported on many ginsenosides with different antidepressant effects and biological mechanisms of action. Of the 12 included articles assessing ginsenoside Rg1, pooled results of forced swimming test from 9 articles (mean difference (MD): 20.50, 95% CI: 16.13-24.87), and sucrose preference test from 11 articles (MD: 28.29, 95% CI: 22.90-33.69) showed significant differences compared with vehicle treatment. The risk of bias of each study was moderate, but there was significant heterogeneity across studies.

CONCLUSION

These estimates suggest that ginsenosides, including ginsenoside Rg1, reduces symptoms of depression, modulates underlying mechanisms, and can be a promising antidepressant.

Dammarane sapogenins attenuates stress-induced anxiety-like behaviors by upregulating ERK/CREB/BDNF pathways

Dammarane sapogenins (DS), an extract derived from ginseng by alkaline hydrolysis of total ginsenosides, possesses high pharmacological activity and higher bioavailability than ginsenosides. The present study was designed to investigate the anxiolytic-like effects of DS in a mouse model of chronic social defeat stress (CSDS). DS (40 and 80 mg/kg) significantly ameliorated social avoidance and anxiety-like behavior in four test models of CSDS, showing increased time in the interaction zone in the social interaction test and in the center of the field in the open field test, an increased percentage of entries and open arm time in the elevated plus maze, and reduced latency to eat in the novelty-suppressed feeding test. Biochemical analyses showed that DS significantly reduced serum corticosterone levels and increased brain concentration of neurotransmitter 5-HT and noradrenaline in CSDS mice. Treatment with DS significantly upregulated BDNF (brain-derived neurotrophic factor), p-CREB/CREB and p-ERK1/2/ERK1/2 protein expression in the hippocampus and prefrontal cortex of CSDS mice. Collectively, these results suggest that DS exerts anxiolytic-like effects in CSDS model mice and the action is mediated, at least in part, by modulating the HPA (hypothalamic-pituitary-adrenal) axis and monoamine neurotransmitter levels, and via ERK/CREB/BDNF signaling pathway.

Potential effect of herbal antidepressants on cognitive deficit: Pharmacological activity and possible molecular mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Cognitive symptom is a "core" symptom of major depressive disorder (MDD) patients with clear deficit in memory, social and occupational function, and may persist during the remitting phase. Therefore, the remission of cognitive symptom has been considered as one of the main objectives in the treatment of MDD. Herbal antidepressants have been used to treat MDD, and there has been great advances in the understanding of the ability of these herbs to improve cognitive deficit linked to brain injury and various diseases including depression, Alzheimer disease, diabetes and age-related disorders. This systematic review summarizes the evidence from preclinical studies and clinical trials of herbal antidepressants with positive effects on cognitive deficit. The potential mechanisms by which herbal antidepressants prevent cognitive deficit are also reviewed. This review will facilitate further research and applications.

MATERIALS AND METHODS

We conducted an open-ended, English restricted search of MEDLINE (PubMed), Web of Science and Scopus for all available articles published or online before 31 December 2019, using terms pertaining to medical herb/phytomedicine/phytochemical/Chinese medicine and depression/major depressive disorder/antidepressant and/or cognitive impairment/cognitive deficit/cognitive dysfunction.

RESULTS

7 prescriptions, more than 30 individual herbs and 50 phytochemicals from China, Japan, Korea and India with positive effects on the depressive state and cognitive deficit are reviewed herein. The evidence from preclinical studies and clinical trials proves that these herbal antidepressants exhibit positive effects on one or more aspects of cognitive defect including spatial, episodic, aversive, and short- and long-term memory. The action mode of the improvement of cognitive deficit by these herbal antidepressants is mediated mainly through two pathways. One pathway is to promote hippocampal neurogenesis through activating brain derived neurotrophic factor-tropomyosin-related kinase B signaling. The other pathway is to prevent neuronal apoptosis through the inhibition of neuro-inflammation and neuro-oxidation.

CONCLUSION

These herbal antidepressants, having potential therapy for cognitive deficit, may prevent pathological processes of neurodegenerative diseases. Furthermore, these herbal medicines should provide a treasure trove, which will accelerate the development of new antidepressants that can effectively improve cognitive symptom in MDD. Studies on their molecular mechanisms may provide more potential targets and therapeutic approaches for new drug discovery.

The protective effect of ginsenoside Rg1 on depression may benefit from the gap junction function in hippocampal astrocytes

Studies have shown that the ginsenoside Rg1 can improve depressive symptoms in vitro and in vivo. However, the efficacy of Rg1on the hippocampal astrocyte gap junctions in depression are unclear. We mainly aimed to explore the relationship between Rg1, hippocampal astrocyte gap junctions and depression. Using primary cultured astrocytes, corticosterone (CORT) was used to induce stress. CORT (100 μM) significantly reduced the survival rate in astrocytes, and this effect was prevented by additional Rg1 administration. Interestingly, the gap junction blocker carbenoxolone (CBX) was able to revert this Rg1 effect. In in vivo models, one group was exposed to chronic unpredictable stress (CUS) for 47 days, while another group was bilaterally injected with CBX (100 μM) into the hippocampal CA1 region. Rats treated with Rg1 (20 mg/kg) showed an improvement in the sucrose preference and the forced swimming test in both models, indicating an antidepressive activity of Rg1. The levels of astrocyte gap junction connexin 43 (Cx43) were detected by immunofluorescence (IF) and western blotting. The levels of glial fibrillary acidic protein (GFAP) were detected by IF. The gap junctions in the hippocampal CA1 area were evaluated using dye transfer and electron microscopy. The reduction in Cx43 expression, the decrease in the Cx43 to GFAP ratio, the shorter dye diffusion distance, and the abnormal ultrastructure of gap junctions in rats exposed to CUS were markedly alleviated by concomitant Rg1 treatment. Taken together, the ginsenoside Rg1 could improve depression-like behavior in rats induced by astrocyte gap junction dysfunction in the hippocampus.

Ginsenoside Rg1 fails to rescue PTSD-like behaviors in a mice model of single-prolonged stress

Previous studies reported that ginsenoside Rg1 (Rg1) exerts antidepressant-like effect in animal models of depression. However, its effect on post-traumatic stress disorder (PTSD) remains elusive; PTSD is a common and costly psychiatric condition with negative cognitive and affective dysfunctions, such as anxiety and depression. In this study, we evaluated the role of Rg1 in a validated mice model of PTSD induced by single-prolonged stress (SPS). Sertraline, one of the FDA-approved medications for PTSD was used as a positive control. Our results showed that SPS exposure led to increased anxiety-like and despair-like behaviors. SPS exposure also caused enhanced contextual fear memory and overgeneralization of learned fear. Sertraline significantly ameliorated those abnormal behaviors induced by SPS, while Rg1 did not. Meanwhile, we found that sertraline but not Rg1 blocked the suppressive effect of SPS on adult neurogenesis in the hippocampus. Consistently, we found that SPS elevated adrenocorticotropic hormone (ACTH) level in the serum, which was inhibited by sertraline but not Rg1. Our results thus demonstrate that Rg1 at a dose used to treat depression may not be effective to rescue behavioral deficits associated with PTSD.

Traditional Chinese Medicine in Depression Treatment: From Molecules to Systems

Depression is a multigenetic or multifactorial syndrome. The central neuron system (CNS)-orientated, single target, and conventional antidepressants are insufficient and far from ideal. Traditional Chinese Medicine (TCM) has historically been used to treat depression up till today, particularly in Asia. Its holistic, multidrug, multitarget nature fits well with the therapeutic idea of systems medicine in depression treatment. Over the past two decades, although efforts have been made to understand TCM herbal antidepressants at the molecular level, many fundamental questions regarding their mechanisms of action remain to be addressed at the systems level in order to better understand the complicated herbal formulations in depression treatment. In this Mini Review, we review and discuss the mechanisms of action of herbal antidepressants and their acting targets in the pathological systems in the brain, such as monoamine neurotransmissions, hypothalamic–pituitary–adrenal (HPA) axis, neurotropic factor brain-derived neurotrophic factor (BDNF) cascade, and glutamate transmission. Some herbal molecules, constituents, and formulas are highlighted as examples to discuss their mechanisms of action and future directions for comprehensive researches at the systems level. Furthermore, we discuss pharmacological approaches to integrate the mechanism of action from the molecular level into the systems level for understanding of systems pharmacology of TCM formulations. Integration of the studies at the molecular level into the systems level not only represents a trend in TCM study but also promotes our understanding of the system-wide mechanism of action of herbal antidepressant formulations.

Ginsenoside Rg1 attenuates chronic unpredictable mild stress-induced depressive-like effect via regulating NF-κB/NLRP3 pathway in rats

Ginsenoside (GS Rg1), which has neuroprotection and anti-inflammation activities, is the main active ingredient of Radix Ginseng. However, its antidepressant-like effect in rats remains unclear. Our study was conducted to investigate whether GS Rg1 confers an antidepressant effect in rats exposed to a chronic unpredictable mild stress model of depression and to explore its possible mechanisms. Our results revealed that GS Rg1 treatments for 3 weeks alleviated the depression-related behaviors of chronic unpredictable mild stress-exposed rats, as indicated by increasing sucrose preference, improving locomotor activity and shortening immobile time in both the forced swimming tests and tail suspension tests. And these ameliorative effects of GS Rg1 treatment were involved with regulating chronic unpredictable mild stress-induced pro-inflammatory cytokine interleukin beta (IL-1β) related neuro-inflammation. In addition, we further found that GS Rg1 reversed chronic unpredictable mild stress-induced IL-1β elevation, possibly by inhibiting nuclear factor kappa B pathway activation and regulating nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 inflammasome expression. In short, our results suggested that GS Rg1 exerted a potential antidepressant-like effect in chronic unpredictable mild stress rat model of depression, which may provide an insight into the potential of GS Rg1 in therapeutic implications for depression.

Bifidobacteria-Fermented Red Ginseng and Its Constituents Ginsenoside Rd and Protopanaxatriol Alleviate Anxiety/Depression in Mice by the Amelioration of Gut Dysbiosis

Gut dysbiosis is closely connected with the outbreak of psychiatric disorders with colitis. Bifidobacteria-fermented red ginseng (fRG) increases the absorption of ginsenoside Rd and protopanxatriol into the blood in volunteers and mice. fRG and Rd alleviates 2,4,6-trinitrobenzenesulfonic acid-induced colitis in mice. Therefore, to understand the gut microbiota-mediated mechanism of fRG against anxiety/depression, we examined the effects of red ginseng (RG), fRG, ginsenoside Rd, and protopanaxatriol on the occurrence of anxiety/depression, colitis, and gut dysbiosis in mice. Mice with anxiety/depression were prepared by being exposed to two stressors, immobilization stress (IS) or Escherichia coli (EC). Treatment with RG and fRG significantly mitigated the stress-induced anxiety/depression-like behaviors in elevated plus maze, light-dark transition, forced swimming (FST), and tail suspension tasks (TST) and reduced corticosterone levels in the blood. Their treatments also suppressed the stress-induced NF-κB activation and NF-κB+/Iba1+ cell population in the hippocampus, while the brain-derived neurotrophic factor (BDNF) expression and BDNF+/NeuN+ cell population were increased. Furthermore, treatment with RG or fRG suppressed the stress-induced colitis: they suppressed myeloperoxidase activity, NF-κB activation, and NF-κB+/CD11c+ cell population in the colon. In particular, fRG suppressed the EC-induced depression-like behaviors in FST and TST and colitis more strongly than RG. fRG treatment also significantly alleviated the EC-induced NF-κB+/Iba1+ cell population and EC-suppressed BDNF+/NeuN+ cell population in the hippocampus more strongly than RG. RG and fRG alleviated EC-induced gut dysbiosis: they increased Bacteroidetes population and decreased Proteobacteria population. Rd and protopanaxatriol also alleviated EC-induced anxiety/depression and colitis. In conclusion, fRG and its constituents Rd and protopanaxatriol mitigated anxiety/depression and colitis by regulating NF-κB-mediated BDNF expression and gut dysbiosis.

Ginsenoside-Rg1 Rescues Stress-Induced Depression-Like Behaviors via Suppression of Oxidative Stress and Neural Inflammation in Rats

Depression is an inflammatory-related condition, with the progression in neuronal damage resulting in major depression disorder. Ginsenoside-Rg1, a sterol extract from the herb Panax ginseng, has been shown to exert neuroprotective effects upon neurodegeneration disorders. However, whether ginsenoside-Rg1 confers antidepressant-like effects on neuroinflammation as associated with depression, as well as the possible mechanism involved in these neuroprotective effects, is currently unclear. In the present report, we show that treatment with ginsenoside-Rg1 (40 mg/kg, i.p.) significantly ameliorated depressive-like behaviors as induced by chronic unpredictable mild stress (CUMS) in a rat model of depression. Moreover, these CUMS rats treated with ginsenoside-Rg1 showed reductions in the levels of the oxidative stress products and the activity in the antioxidant stress kinase. Furthermore, CUMS rats treated with ginsenoside-Rg1 showed ameliorated neuroinflammation and associated neuronal apoptosis along with a reduction in dendritic spine atrophy and display of depressive behaviors. Taken together, the results of this study suggest that ginsenoside-Rg1 produces antidepressant-like effects in CUMS-exposed rats; and one of the mechanisms for these antidepressant-like effects of ginsenoside-Rg1 appears to involve protection against oxidative stress and thus the neuronal deterioration resulting from inflammatory responses. These findings provide evidence for the therapeutic potential of ginsenoside-Rg1 in the treatment of stress-related depression.

Dammarane sapogenins alleviates depression-like behaviours induced by chronic social defeat stress in mice through the promotion of the BDNF signalling pathway and neurogenesis in the hippocampus

Chronic social defeat stress (CSDS) is a widely used behavioural paradigm of psychosocial stress that can be used to research the pathogenesis of depression and seek antidepressant drugs. Dammarane sapogenins (DS), the deglycosylated product of ginsenosides, has a wide range of biological activities, including immunomodulatory, antifatigue, antitumour and antidepressant activities. However, whether DS has antidepressant-like effects in a CSDS mouse model remains unknown. Therefore, the present study was conducted to evaluate the antidepressant properties of DS in CSDS mice and its underlying mechanisms. The results showed that the oral administration of DS (40 and 80 mg/kg) increased the time spent in the interaction zone in the social interaction test and the sucrose intake in the sucrose preference test, decreased the latency in the novelty-suppressed feeding test, and reduced the immobility time in both the tail suspension test and forced swimming test. Biochemical analyses of brain tissue and serum showed that DS treatment significantly decreased serum corticosterone levels and enhanced brain monoamine neurotransmitter levels in CSDS mice. In addition, an impairment in hippocampal neurogenesis that paralleled a reduced BDNF level in the hippocampus was observed in the mice that were subjected with CSDS for 3 weeks, while treatment with DS reversed these changes. Moreover, DS treatment significantly upregulated BDNF, pTrkB/TrkB, pAkt/Akt, pPI3K/PI3K, pCREB/CREB, pERK1/2/ERK1/2 and pmTOR/mTOR protein expression in the hippocampus. In conclusion, our results showed that DS exerts antidepressant-like effects in mice with CSDS-induced depression, that the effects may be mediated by the normalization of monoamine neurotransmitter levels, the prevention of HPA axis dysfunction and the impairment of hippocampal neurogenesis, and that this occurs partly through the ability of DS to enhance BDNF expression by increasing the TrkB/CREB/ERK pathway and the PI3K/AKT/mTOR pathway.

Mechanisms of Panax ginseng action as an antidepressant

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Antidepressant-like effects of the Guanxin Danshen formula via mediation of the CaMK II-CREB-BDNF signalling pathway in chronic unpredictable mild stress-induced depressive rats

Background

Depression is a chronic and recurrent syndrome of mood disorder causing immense social and economic burden; thus, treatment should be improved. Guanxin Danshen formula (GXDSF), a natural botanical drug composition prescription, has significant cardiovascular protective effects and is widely used in the clinical treatment of myocardial ischaemic diseases. However, it is still unclear and seldom studied whether GXDSF has neuroprotective effects against depressive disorders. This study explored whether GXDSF has antidepressant-like effects in rats exposed to chronic unpredictable mild stress (CUMS) and analysed the possible underlying neurotrophic expression and psychotropic mechanisms.

Methods

The present study was designed to investigate the antidepressant effects of GXDSF treatment in a CUMS-induced rat model. Based on the clinical doses, the drug-treated group was intragastrically administered GXDSF for 30 days, and rats were simultaneously exposed to CUMS stimulation for 30 days. After induction and drug administration, the depression-like behaviours were determined via the sucrose preference test (SPT), the open field test (OFT), the tail suspension test (TST), and the forced swim test (FST). ELISA kits were used to examine the monoaminergic neurotransmitters, monoamine oxidase (MAO) and Ca²⁺ levels in the hippocampus. Moreover, we measured and analysed the brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels and the upstream regulation and signal pathways of BDNF and NGF to explore their related mechanisms in this animal model of depression, including calcium-calmodulin dependent protein kinase-II (CaMKII) and cAMP response element-binding (CREB).

Results

The results revealed that GXDSF may possess significant antidepressant-like effects via improving body weight, raising the sucrose preference in the SPT, increasing the total distance, the number of upright stands, and the residence time of the central zone in the open field test (OPF) and reducing the immobility time in the TST and FST. In addition, GXDSF significantly upregulated the relative levels of neurotransmitters, including dopamine (DA), norepinephrine (NE), and serotonin (5-HT), in a dose-dependent manner and inhibited MAO activities in the hippocampus. Moreover, GXDSF reversed the decline in intracellular CREB and p-CREB expression induced by CUMS, downregulated the phosphorylation levels of intracellular CaMKII and its two subunits CaMKIIα and CaMKIIβ in the hippocampus, and thus, clearly upregulated the downstream effector protein expression levels of BDNF, NGF, and synitaxine-1 in the hippocampus. These data suggest that the antidepressant effects of GXDSF have a potential relationship with regulating changes in the CaMKII-CREB-BDNF pathway.

Conclusions

Despite several limitations of this study, the results have suggested that GXDSF administration possesses antidepressant-like effects in CUMS-treated rats and provide the first in vivo demonstration of a possible mechanism of GXDSF via regulating changes in the CaMKII-CREB-BDNF signalling pathway. These findings provide a novel potential substrate by which herbal antidepressants may exert therapeutic effects in the treatment of depression.

Neuroprotective Effects of Ginsenoside-Rg1 Against Depression-Like Behaviors via Suppressing Glial Activation, Synaptic Deficits, and Neuronal Apoptosis in Rats

Depression is considered a neuropsychiatric disease associated with various neuronal changes within specific brain regions. We previously reported that ginsenoside-Rg1, a potential neuroprotective agent extracted from ginseng, significantly alleviated depressive-like disorders induced by chronic stress in rats. However, the mechanisms by which ginsenoside-Rg1 exerts its neuroprotective effects in depression remain largely uncharacterized. In the present study we confirm that ginsenoside-Rg1 significantly prevented the antidepressant-like effects in a rat model of chronic unpredictable mild stress (CUMS) and report on some of the underlying mechanisms associated with this effect. Specifically, we found that chronic pretreatment with ginsenoside-Rg1 prior to stress exposure significantly suppressed inflammatory pathway activity via alleviating the overexpression of proinflammatory cytokines and the activation of microglia and astrocytes. These effects were accompanied with an attenuation of dendritic spine and synaptic deficits as associated with an upregulation of synaptic-related proteins in the ventral medial prefrontal cortex (vmPFC). In addition, ginsenoside-Rg1 inhibited neuronal apoptosis induced by CUMS exposure, increased Bcl-2 expression and decreased cleaved Caspase-3 and Caspase-9 expression within the vmPFC region. Furthermore, ginsenoside-Rg1 could increase the nuclear factor erythroid 2-related factor (Nrf2) expression and inhibit p38 mitogen-activated protein kinase (p-p38 MAPK) and nuclear factor κB (NF-κB) p65 subunit activation within the vmPFC. Taken together, these results suggest that the neuroprotective effects of ginsenoside-Rg1, which may assume the antidepressant-like effect in this animal model of depression, appears to result from amelioration of a CUMS-dependent neuronal deterioration within the vmPFC. Moreover, they also provide support for the therapeutic potential of ginsenoside-Rg1 in the treatment of stress-related mental disorders.

Active components, derived from Kai-xin-san, a herbal formula, increase the expressions of neurotrophic factor NGF and BDNF on mouse astrocyte primary cultures via cAMP-dependent signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Kai-Xin-San (KXS), an ancient formula composed of Ginseng Radix et Rhizoma, Polygalae Radix, Acori Tatarinowii Rhizoma and Poria, was frequently applied for Alzheimer's disease and major depression disorders for thousands of years. However, its active components and molecular mechanism have not clearly been investigated.

AIM OF THE STUDY

We aimed to reveal the active components of KXS on regulating neurotrophic factor NGF and BDNF expressions and its mechanisms on mouse astrocyte primary cultures.

MATERIALS AND METHODS

Extracts of KXS had been prepared by water reflux and chemical standardization was carried out by HPLC-MS/MS. Various ethanol elution components were prepared by eluting ethanol on macro pore resin column and compound identification was carried out by high-resolution mass spectrometry. KXS extract, elution components and identified chemicals were applied on mouse astrocytes and expressions of NGF and BDNF and related metabolic enzymes were analyzed by qPCR and western blotting analysis.

RESULTS

One compatible ratio of KXS named D-652 exerted the best effect on stimulation of NGF and BDNF expressions on mouse astrocytes. 70% ethanol elution fraction of D-652 exerted the highest increase tendency on expressions of NGF and BDNF by activating cAMP-dependent signaling pathway as well as stimulating enzymes accounting for neurotrophic factor synthesis. Combined with compound identification by high-resolution mass spectrometry, ginsenoside Rg₁ and Rb₁ might be the active compounds of this fraction on increasing NGF and BDNF expressions.

CONCLUSIONS

The active compounds of KXS on increasing NGF and BDNF expressions might be the ginsenosides via activating cAMP-dependent signaling pathway as well as stimulating enzymes accounting for neurotrophic factor synthesis, which partly reveal the target of this formulae supported the clinically usage of this decoction.

Emerging signals modulating potential of ginseng and its active compounds focusing on neurodegenerative diseases

Common features of neurodegenerative diseases (NDDs) include progressive dysfunctions and neuronal injuries leading to deterioration in normal brain functions. At present, ginseng is one of the most frequently used natural products. Its use has a long history as a cure for various diseases because its extracts and active compounds exhibit several pharmacological properties against several disorders. However, the pathophysiology of NDDs is not fully clear, but researchers have found that various ion channels and specific signaling pathways might have contributed to the disease pathogenesis. Apart from the different pharmacological potentials, ginseng and its active compounds modulate various ion channels and specific molecular signaling pathways related to the nervous system. Here, we discuss the signal modulating potential of ginseng and its active compounds mainly focusing on those relevant to NDDs.

MiR-134 modulates chronic stress-induced structural plasticity and depression-like behaviors via downregulation of Limk1/cofilin signaling in rats

Increasing evidence has suggested that depression is a neuropsychiatric condition associated with neuroplasticity within specific brain regions. However, the mechanisms by which neuroplasticity exerts its effects in depression remain largely uncharacterized. In the present study we show that chronic stress effectively induces depression-like behaviors in rats, an effect which was associated with structural changes in dendritic spines and synapse abnormalities within neurons of the ventromedial prefrontal cortex (vmPFC). Moreover, unpredictable chronic mild stress (UCMS) exposure significantly increased the expression of miR-134 within the vmPFC, an effect which was paralleled with a decrease in the levels of expression and phosphorylation of the synapse-associated proteins, LIM-domain kinase 1 (Limk1) and cofilin. An intracerebral infusion of the adenovirus associated virus (AAV)-miR-134-sponge into the vmPFC of stressed rats, which blocks mir-134 function, significantly ameliorated neuronal structural abnormalities, biochemical changes and depression-like behaviors. Chronic administration of ginsenoside Rg1 (40 mg/kg, 5 weeks), a potential neuroprotective agent extracted from ginseng, significantly ameliorated the behavioral and biochemical changes induced by UCMS exposure. These results suggest that miR-134-mediated dysregulation of structural plasticity may be related to the display of depression-like behaviors in stressed rats. The neuroprotective effects of ginsenoside Rg1, which produces an antidepressant like effect in this model of depression, appears to result from modulation of the miR-134 signaling pathway within the vmPFC.

Botanicals as Modulators of Neuroplasticity: Focus on BDNF

The involvement of brain-derived neurotrophic factor (BDNF) in different central nervous system (CNS) diseases suggests that this neurotrophin may represent an interesting and reliable therapeutic target. Accordingly, the search for new compounds, also from natural sources, able to modulate BDNF has been increasingly explored. The present review considers the literature on the effects of botanicals on BDNF. Botanicals considered were Bacopa monnieri (L.) Pennell, Coffea arabica L., Crocus sativus L., Eleutherococcus senticosus Maxim., Camellia sinensis (L.) Kuntze (green tea), Ginkgo biloba L., Hypericum perforatum L., Olea europaea L. (olive oil), Panax ginseng C.A. Meyer, Rhodiola rosea L., Salvia miltiorrhiza Bunge, Vitis vinifera L., Withania somnifera (L.) Dunal, and Perilla frutescens (L.) Britton. The effect of the active principles responsible for the efficacy of the extracts is reviewed and discussed as well. The high number of articles published (more than one hundred manuscripts for 14 botanicals) supports the growing interest in the use of natural products as BDNF modulators. The studies reported strengthen the hypothesis that botanicals may be considered useful modulators of BDNF in CNS diseases, without high side effects. Further clinical studies are mandatory to confirm botanicals as preventive agents or as useful adjuvant to the pharmacological treatment.

Ginsenoside Rg1 Ameliorates Behavioral Abnormalities and Modulates the Hippocampal Proteomic Change in Triple Transgenic Mice of Alzheimer's Disease

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, so far, there are no effective measures to prevent and cure this deadly condition. Ginsenoside Rg1 (Rg1) was shown to improve behavioral abnormalities in AD; however, the potential mechanisms remain unclear. In this study, we pretreated 7-month-old 3xTg-AD mice for 6 weeks with Rg1 and evaluated the effects of Rg1 on the behaviors and the protein expression of hippocampal tissues. The behavioral tests showed that Rg1 could improve the memory impairment and ameliorate the depression-like behaviors of 3xTg-AD mice. Proteomic results revealed a total of 28 differentially expressed hippocampal proteins between Rg1-treated and nontreated 3xTg-AD mice. Among these proteins, complexin-2 (CPLX2), synapsin-2 (SYN2), and synaptosomal-associated protein 25 (SNP25) were significantly downregulated in the hippocampus of 3xTg-AD mice compared with the WT mice, and the treatment of Rg1 modulated the expression of CPLX2 and SNP25 in the hippocampus of 3xTg-AD mice. The expression of CPLX2, SYN2, and SNP25 was further validated by Western blot analysis. Taken together, we concluded that Rg1 could be a potential candidate drug to improve the behavioral deficits in AD via modulating the expression of the proteins (i.e., CPLX2, SYN2, and SNP25).

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

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

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

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

Antidepressive effects of ginsenoside Rg1 via regulation of HPA and HPG axis

BACKGROUND

Hypothalamic-pituitary-adrenal (HPA) axis hyperactivity is a well-established pathological feature of major depression, accompanied by the persistent increase of glucocorticoid level and the dysfunction of hypothalamic-pituitary-gonadal (HPG) axis. Ginsenoside Rg1 (Rg1) is one of the most active ingredients of Panax ginseng, which has various biological activity.

OBJECTIVE

This study aimed to investigate the antidepressive effects of Rg1 and elucidate its impact on neuroendocrine system.

METHODS

The antidepressive effects of Rg1 were first analysed in mice, and was further identified in the chronic-unpredictable-mild-stress (CUMS) model and the gonadectomized (GDX) model. The effects of Rg1 on depression-like behaviour were analysed by the forced swimming test (FST), tail suspension test (TST), sucrose preference test, and measurement of pentobarbital-induced sleep. The serum corticosterone and testosterone levels were detected by ELISA. The protein levels of glucocorticoid receptor (GR) and androgen receptor (AR) were analysed by western blot and immunohistochemistry analysis.

RESULTS

Rg1 significantly decreased the immobility time of mice in FST and TST. Furthermore, Rg1 alleviated anhedonia and hopelessness, decreased serum corticosterone level, and increased serum testosterone level, and the GR protein level in the PFC and hippocampus of the CUMS-treated rats. Moreover, Rg1 improved sleep disruption, down-regulated the serum corticosterone level, and increased AR protein level in the PFC of the GDX-treated mice.

CONCLUSION

Together, these studies suggest that Rg1 displayed antidepressant activity through the modulation of the HPA and the HPG axis. These findings provide new mechanism involved in the antidepressive effects of Rg1 and propose theoretical clues for clinical therapies.

Gintonin attenuates depressive-like behaviors associated with alcohol withdrawal in mice

BACKGROUND

Panax ginseng Meyer extracts have been used to improve mood and alleviate symptoms of depression. However, little is known about the extracts' active ingredients and the molecular mechanisms underlying their reported anti-depressive effects.

METHODS

Gintonin is an exogenous lysophosphatidic acid (LPA) receptor ligand isolated from P. ginseng. BON cells, an enterochromaffin cell line, and C57BL/6 mice were used to investigate whether gintonin stimulates serotonin release. Furthermore, the effects of gintonin on depressive-like behaviors following alcohol withdrawal were evaluated using the forced swim and tail suspension tests.

RESULTS

Treatment of BON cells with gintonin induced a transient increase in the intracellular calcium concentration and serotonin release in a concentration- and time-dependent manner via the LPA receptor signaling pathway. Oral administration of the gintonin-enriched fraction (GEF) induced an increase in the plasma serotonin concentration in the mice. Oral administration of the GEF in mice with alcohol withdrawal decreased the immobility time in two depression-like behavioral tests and restored the alcohol withdrawal-induced serotonin decrease in plasma levels.

LIMITATIONS

We cannot exclude the possibility that the gintonin-mediated regulation of adrenal catecholamine release in the peripheral system, and acetylcholine and glutamate release in the central nervous system, could also contribute to the alleviation of depressive-like behaviors.

CONCLUSION

The GEF-mediated attenuation of depressive-like behavior induced by alcohol withdrawal may be mediated by serotonin release from intestinal enterochromaffin cells. Therefore, the GEF might be responsible for the ginseng extract-induced alleviation of depression-related symptoms.

Ginsenoside Rg1-induced antidepressant effects involve the protection of astrocyte gap junctions within the prefrontal cortex

Ginsenoside Rg1 (Rg1) exhibits antidepressant-like activity by increasing neurogenesis and dendritic spine density without discernible side effects. However, the molecular mechanisms underlying Rg1 antidepressant activity remain poorly understood. As the dysfunction of gap junctions between astrocytes in the prefrontal cortex (PFC) is implicated in major depression disorder, the aim of this study was to investigate the effects of Rg1 on astrocyte gap junctions in the PFC. Rats exposed to chronic unpredictable stress (CUS) were administered Rg1 (5, 10, and 20mg/kg) for 28days and analyzed for depressive symptoms using the sucrose preference and forced swimming tests. Functional and morphological changes of gap junction channels in the PFC were evaluated using dye transfer and electron microscopy, respectively. The expression of connexin 43 (Cx43) was analyzed by western blotting. Rg1 markedly alleviated depression-like behavior in rats. Long-term Rg1 treatment of CUS-exposed rats also significantly prevented the decrease in dye diffusion and improved the ultrastructure of astrocyte gap junctions in the PFC, indicating beneficial effects on the functional activity of gap junction channels in the brain. In addition, Rg1 upregulated Cx43 expression in the PFC reduced by CUS exposure, which significantly correlated with its antidepressant-like effects. The results demonstrate that Rg1-induced antidepressant effects are might be mediated, in part, by protecting astrocyte gap junctions within the prefrontal cortex.

Neurological mechanism of Xiaochaihutang's antidepressant-like effects to socially isolated adult rats

Objectives

Xiaochaihutang (XCHT) has antidepressant effects in multiple animal models of depression in our previous studies. But the antidepressant effects and exact mechanisms of XCHT in a rat model of chronic social isolation stress (CSIS) have never been studied. We therefore aimed to investigate the effects of XCHT on depressive/anxiety-related behaviours of CSIS-exposed rats and understand the neurological mechanism involving neurogenesis.

Methods

We established the CSIS model and then investigated the effects of XCHT on behavioural change. HPLC-MS/MS was adopted to quantify neurotransmitter levels in the cerebrospinal fluid (CSF). Immunofluorescence technology was used to study the effects of XCHT on neurogenesis; while expressions of 5-HT1A receptor signalling pathway in the hippocampus were measured using Western blotting.

Key Findings

Xiaochaihutang significantly alleviated depressive/anxiety-like behaviours of CSIS-exposed rats. XCHT significantly regulated levels of monoamine neurotransmitters in the CSF without affecting Glu, GABA and ACh. XCHT also significantly increased neurogenesis in CSIS-exposed rats. Additionally, XCHT reversed CSIS-induced decrease of 5-HT1A receptor expression and promoted the expression of BDNF in the hippocampus.

Conclusion

Our results suggest that XCHT could significantly regulate the depressive/anxiety-like behaviours induced by CSIS, which are likely attributed to the promotion of hippocampal neurogenesis and neurotrophin expressions through the activation of serotonergic system.