Antidepressant-like effects of water extract of Gastrodia elata Blume on neurotrophic regulation in a chronic social defeat stress model

Neuropharmacological effects of Gastrodia elata Blume and its active ingredients

Gastrodia elata Blume (GE), a traditional Chinese medicine clinically employed to treat neurological disorders, demonstrates therapeutic efficacy supported by robust clinical evidence. Nowadays, conventional pharmacotherapies for neurological conditions-such as cholinesterase inhibitors for Alzheimer's or Ldopa for Parkinson's-often provide limited symptom relief, exhibit side effects, and fail to halt disease w, underscoring the need for alternative strategies. The primary bioactive compounds of Gastrodia elata Blume (GE) include gastrodin, p-hydroxybenzyl alcohol, Vanillyl alcohol, Polysaccharides, and β-sitosterol. Modern research has demonstrated that GE and its active components exhibit neuropharmacological effects, including neuron protection, reduction of neurotoxicity, and promotion of nerve regeneration and survival. For example, Gastrodin, exerts neuroprotection by scavenging reactive oxygen species, suppressing pro-inflammatory cytokines, and enhancing GABAergic transmission, thereby alleviating oxidative stress and neuronal apoptosis. Vanillin, potentiates GABA receptor activity, enhancing inhibitory neurotransmission and reducing seizure susceptibility.GE polysaccharides modulate the gut-brain axis and suppress microglial activation, mitigating neuroinflammation. Current studies primarily focus on GE and its active ingredients for the treatment of neurological diseases such as Parkinson's disease, Alzheimer's disease, epilepsy, convulsions, depression, schizophrenia, as well as enhancing learning and memory, and preventing or treating cerebral ischemic injury. This review explores the neuropharmacological effects of GE and its active compounds, elucidates the underlying mechanisms, and suggests potential preventive and therapeutic strategies for neurological diseases using herbal remedies.

A comprehensive pharmacology study reveals the molecular mechanisms underlying the antidepressant effects of Gastrodiae Rhizoma

BACKGROUND

Gastrodiae Rhizoma (GR) and its extract have been widely used in the treatment of depression, but the underlying mechanism of its antidepressant effects is unclear due to its numerous components.

PURPOSE

Revealing the cellular and molecular mechanisms underlying the antidepressant effects of GR through a comprehensive pharmacology-based in vivo and in vitro investigation.

METHODS

A mouse model of depression was established using chronic mild stress (CMS) procedure, and the antidepressant effects of GR were evaluated using systematic behavior. Metabolites in GR decoction and in mouse brain were identified by UPLC-QTOF-MS technology. Core components and targets of GR against MDD were screened based on network pharmacology analysis and molecular docking. The mechanism through which GR mitigated MDD was explored using transcriptome analysis, immunohistochemistry and western blotting in vitro and in vivo.

RESULTS

A total of 273 components were identified in the GR decoction, out of which 15 were detected in the brain of depressed mice treated with the GR decoction. We further identified nine key active ingredients, six essential targets, and fifth signaling pathways associated with the therapeutic effects of GR against MDD. We confirmed that the active ingredients of GR can target the neural stem/precursor cells (NSPCs) in the hippocampus of depressed mice to promote neurogenesis, as evidenced by a significant increase in the numbers of DCX+ cells, BrdU+ cells, BrdU+-DCX+ cells, and BrdU+-NeuN+ cells within the hippocampus of GR-treated mice compared to salinetreated mice under CMS exposure. Moreover, we have identified that the key active constituents of GR, namely gastrodin and parishin C, exert a targeted effect on EGFR to activate PI3K-Akt signaling in NSPCs, thereby facilitating proliferation and differentiation of NSPCs.

CONCLUSION

The antidepressant effect of GR involves the facilitation of PI3K/Akt-mediated neurogenesis through gastrodin and parishin C targeting EGFR in NSPCs.

Variation in SSRs at different genomic regions and implications for the evolution and identification of Armillaria gallica

Armillaria spp. are devastating forest pathogens. Due to its low pathogenicity and abundant genetic variation, Armillaria gallica exhibited a unique and beneficial symbiosis with Gastrodia elata, which was used as a traditional Chinese medicine. However, the variation and population structure of A. gallica populations have rarely been investigated. Hence, we analyzed the evolution and variation in simple sequence repeats (SSRs) in three Armillaria genomes: A. gallica, A. cepistipes, and A. ostoyae to assess the genetic diversity and population structure of 14 A. gallica strains. Genome analysis revealed that SSRs were more abundant in the intergenic region than the intron and exon region, as was the SSR density. Compared with other two genomes, SSR density was the lowest in exon region and largest in the intron region of A. gallica, with significant variation in genic region. There were 17 polymorphic markers in A. gallica genome was identified, with 26.7% in genic region, which is higher than that of 18.8% in the intergenic region. Moreover, a total of 50 alleles and 42 polymorphic loci were detected among these A. gallica strains. The averaged polymorphism information content (PIC) was 0.4487, ranged from 0.2577 to 0.6786. Both principal coordinate analysis (PCoA) and population structure analyses based on the genotype data of SSRs divided the strains into two clusters. The cluster I included all the strains from high-altitude G. elata producing areas and some low-altitude areas, while the strains in Cluster II originated from low-altitude G. elata producing areas. These results indicated that substantial genome-specific variation in SSRs within the genic region of A. gallica and provide new insights for further studies on the evolution and breeding of A. gallica.

A Review of Gastrodia Elata Bl.: Extraction, Analysis and Application of Functional Food

Gastrodia elata Bl. still widely known as a medicinal plant due to its anti-inflammatory, neuroprotection, cardiovascular protection etc. Additionally, these medical applications cannot be separated from its antioxidant, anti-aging, regulating cell apoptosis ability, which make it have potential as a functional food as well as it has been eaten for more than 2,000 years in China. At present, although Gastrodia elata Bl. has appeared in a large number of studies, much of the research is based on drugs rather than foods. The review of Gastrodia elata Bl. from the perspective of food is one of the necessary steps to promote related development, by reviewing the literature on analytical methods of Gastrodia elata Bl. in recent years, critical components change in the extraction, analytical methods and improvement of food applications, all of aspects of it was summarized. Based on the report about physical and chemical changes in Gastrodia elata Bl. to discover the pathway of Gastrodia elata Bl. functional food development from current to the future.

Digestive characteristics of Gastrodia elata Blume polysaccharide and related impacts on human gut microbiota in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Gastrodia elata Blume is a traditional Chinese medicine with the effects of improving the deficiency of the body and maintaining health, and polysaccharide (GEP) is one of the effective ingredients to play these activities of G. elata. Traditionally, G. elata is orally administered, so the activities of GEP are associated with digestive and intestinal metabolism. However, the digestive behavior of GEP and its effects on the human gut microbiota are unclear and need to be fully studied.

AIM OF THE STUDY

This study aimed to investigate the changes in structural characteristics of GEP during digestion and the related impacts of its digestive product on gut microbiota in human fecal fermentation, and to explain the beneficial mechanism of GEP on human health from the perspective of digestive characteristics and "gut" axis.

MATERIALS AND METHODS

The changes of reducing sugars, free monosaccharides and physicochemical properties of GEP during digestion were investigated by GPC, HPLC, FT-IR, CD, NMR, SEM, and TGA. Moreover, polysaccharide consumption, pH value changes, SCFAs production, and changes in gut microbiota during fermentation were also discussed.

RESULTS

During digestion of GEP, glucose was partially released causing a decrease in molecular weight, and a change in monosaccharide composition. In addition, the characteristics of GEP before and after digestion, including configuration, morphology, and stability, were different. The digestive product of GEP was polysaccharide (GEP-I), which actively participated in the fecal fermentation process. As the fermentation time increased, the utilization of GEP-I by the microbiota gradually increased. The abundance of probiotics such as Bifidobacterium, Collinsella, Prevotella, and Faecalibacterium was significantly increased, and the abundance of pathogenic Shigella, Dorea, Desulfovibrio, and Blautia was significantly inhibited, thereby suggesting that GEP has the potential to maintain human health through the "gut" axis. In addition, the beneficial health effects of GEP-I have also been observed in the influence of microbial metabolites. During the fermentation of GEP-I, the pH value gradually decreased, and the contents of beneficial metabolites such as acetic acid, propionic acid, and caproic acid significantly increased.

CONCLUSION

The structure of GEP changed significantly during digestion, and its digestive product had the potential to maintain human health by regulating gut microbiota, which may be one of the active mechanisms of GEP.

Antidepressant effects of Parishin C in chronic social defeat stress-induced depressive mice

ETHNOPHARMACOLOGY RELEVANCE

Parishin C (Par), a prominent bioactive compound in Gastrodia elata Blume with little toxicity and shown neuroprotective effects. However, its impact on depression remains largely unexplored.

AIM OF THE STUDY

This study aims to investigate the antidepressant effects of Par using a chronic social defeat stress (CSDS) mouse model and elucidate its molecular mechanisms.

MATERIALS AND METHODS

The CSDS-induced depression mouse model was used to evaluate the therapeutic efficacy of Par. The social interaction test (SIT) and sucrose preference test (SPT), tail suspension test (TST) and forced swim test (FST) were conducted to assess the effects of Par on depressive-like behaviours. The levels of corticosterone, neurotransmitters (5-HT, DA and NE) and inflammatory cytokines (IL-1β, TNF-α, and IL-6) were evaluated by enzyme-linked immunosorbent assay (ELISA). Activation of a microglia was assessed by immunofluorescence labeling Iba-1. The protein expressions of NLRP3, ASC, caspase-1, and IL-6 verified by Western blot.

RESULT

Oral administration of Par (4 and 8 mg/kg) and fluoxetine (10 mg/kg, administration significantly ameliorate depression-like behaviors induced by CSDS, as shown by the increase social interaction in SIT, increase sucrose preference in SPT and the decrease immobility in TST and FST. Par administration decreased serum corticosterone level and increased the 5-HT, DA and NE concentration in the hippocampus and prefrontal cortex. Furthermore, Par treatment suppressed microglial activation (Iba1) as well as reduced levels of IL-1β, TNF-α, and IL-6) with decreased protein expressions of NLRP3, ASC, caspase-1, and IL-6.

CONCLUSIONS

our study provides the first evidence that Par exerts antidepressant-like effects in mice with CSDS-induced depression. This effect appears to be mediated by the normalization of neurotransmitter and corticosterone levels, inhibition of NLRP3 inflammasome activation. This newfound antidepressant property of Par offers a novel perspective on its pharmacological effects, providing valuable insights into its potential therapeutic and preventive applications in depression treatment.

Mechanisms for the biological activity of Gastrodia elata Blume and its constituents: A comprehensive review on sedative-hypnotic, and antidepressant properties

BACKGROUND

Insomnia and depressive disorder are two common symptoms with a reciprocal causal relationship in clinical practice, which are usually manifested in comorbid form. Several medications have been widely used in the treatment of insomnia and depression, but most of these drugs show non-negligible side effects. Currently, many treatments are indicated for insomnia and depressive symptom, including Chinese herbal medicine such as Gastrodia elata Blume (G. elata), which has excellent sedative-hypnotic and antidepressant effects in clinical and animal studies.

PURPOSE

To summarize the mechanisms of insomnia and depression and the structure-activity mechanism for G. elata to alleviate these symptoms, particularly by hypothalamic-pituitary-adrenal (HPA) axis and intestinal flora, aiming to discover new approaches for the treatment of insomnia and depression.

METHODS

The following electronic databases were searched from the beginning to November 2023: PubMed, Web of Science, Google Scholar, Wanfang Database, and CNKI. The following keywords of G. elata were used truncated with other relevant topic terms, such as depression, insomnia, antidepressant, sedative-hypnotic, neuroprotection, application, safety, and toxicity.

RESULTS

Natural compounds derived from G. elata could alleviate insomnia and depressive disorder, which is involved in monoamine neurotransmitters, inflammatory response, oxidative stress, and gut microbes, etc. Several clinical trials showed that G. elata-derived natural compounds that treat depression and insomnia have significant and safe therapeutic effects, but further well-designed clinical and toxicological studies are needed.

CONCLUSION

G. elata exerts a critical role in treating depression and insomnia due to its multi-targeting properties and fewer side effects. However, more clinical and toxicological studies should be performed to further explore the sedative-hypnotic and antidepressant mechanisms of G. elata and provide more evidence and recommendations for its clinical application. Our review provides an overview of G. elata treating insomnia with depression for future research direction.

An exploration of mechanism of high quality and yield of Gastrodia elata Bl. f. glauca by the isolation, identification, and evaluation of Mycena

Gastrodia elata Bl. f. glauca is an important traditional Chinese medicinal plant. The yield and quality of Gastrodia elata Bl. have significantly decreased due to multigenerational asexual reproduction. Therefore, it is necessary to have sexual reproduction of Gastrodia elata Bl. to supplement the market supply. Seeds of G. elata Bl. have no endosperm, and their sexual reproduction depends on the nutrients provided by the embryo cells infected by Mycena fungi to complete seed germination. However, Mycena fungi are small and have many species, and not all Mycena fungi can promote the germination of G. elata Bl. seeds. Therefore, it is of great significance to isolate and identify suitable germination fungi and explore the mechanism for improving the production performance and yield, and quality of G. elata Bl. Six closely related Mycena isolates, JFGL-01, JFGL-02, JFGL-03, JFGL-04, JFGL-05, and JFGL-06, were isolated from the leaves and protocorms of G. elata Bl. f. glauca and were identified as Mycena purpureofusca. The mycelial state and number of germinating protocorms were used as indicators to preferentially select Mycena fungi, and it was concluded that JFGL-06 had the best mycelial state and ability to germinate G. elata Bl. seeds. Finally, a mechanism to increase the yield of G. elata Bl. was explored by comparing the changes in nutrient elements and microbial diversity in the soil around G. elata Bl. with different strains. JFGL-06 proved to be an excellent Mycena fungal strain suitable for G. elata Bl. f. glauca. Compared with the commercial strain, JFGL-06 significantly increased the C, N, Na, Mg, S, Cl, K, Ca, and Fe contents of the soil surrounding the protocorms of G. elata Bl. f. glauca. JFGL-06 improved the composition, diversity, and metabolic function of the surrounding soil microbial community of G. elata Bl. f. glauca protocorms at the phylum, class, and genus levels, significantly increased the relative abundance of bacteria such as Acidobacteria and fungi such as Trichoderma among the dominant groups, and increased the abundance of functional genes in metabolic pathways such as nucleotide metabolism and energy metabolism. There was a significant reduction in the relative abundance of bacteria, such as Actinomycetes, and fungi, such as Fusarium, in the dominant flora, and a reduced abundance of functional genes, such as amino acid metabolism and xenobiotic biodegradation and metabolism. This is the main reason why the JFGL-06 strain promoted high-quality and high-yield G. elata Bl. f. glauca in Changbai Mountain.

Bioactivity Profiling and Quantification of Gastrodin in Gastrodia elata Cultivated in the Field versus Facility via Hyphenated High-Performance Thin-Layer Chromatography

Gastrodia elata (Orchidaceae) is native to mountainous areas of Asia and is a plant species used in traditional medicine for more than two thousand years. The species was reported to have many biological activities, such as neuroprotective, antioxidant, and anti-inflammatory activity. After many years of extensive exploitation from the wild, the plant was added to lists of endangered species. Since its desired cultivation is considered difficult, innovative cultivation methods that can reduce the costs of using new soil in each cycle and at the same time avoid contamination with pathogens and chemicals are urgently needed on large scale. In this work, five G. elata samples cultivated in a facility utilizing electron beam-treated soil were compared to two samples grown in the field concerning their chemical composition and bioactivity. Using hyphenated high-performance thin-layer chromatography (HPTLC) and multi-imaging (UV/Vis/FLD, also after derivatization), the chemical marker compound gastrodin was quantified in the seven G. elata rhizome/tuber samples, which showed differences in their contents between facility and field samples and between samples collected during different seasons. Parishin E was also found to be present. Combining HPTLC with on-surface (bio)assays, the antioxidant activity and inhibition of acetylcholinesterase as well as the absence of cytotoxicity against human cells were demonstrated and compared between samples.

Anti-depressive-like and cognitive impairment alleviation effects of Gastrodia elata Blume water extract is related to gut microbiome remodeling in ApoE-/- mice exposed to unpredictable chronic mild stress

ETHNOPHARMACOLOGY RELEVANCE

Gastrodia elata Blume (GE) is a traditional Chinese dietary therapy used to treat neurological disorders. Gastrodia elata Blume water extract (WGE) has been shown to ameliorate inflammation and improve social frustration in mice in a chronic social defeat model. However, studies on the anti-depressive-like effects and cognitive impairment alleviation related to the impact of WGE on the gut microbiome of ApoE-/- mice remain elusive.

AIM OF THE STUDY

The present study aimed to investigate the anti-depressive-like effect and cognitive impairment alleviation and mechanisms of WGE in ApoE-/- mice subjected to unpredictable chronic mild stress (UCMS), as well as its impact on the gut microbiome of the mice.

MATERIALS AND METHODS

Sixty ApoE-/- mice (6 months old) were randomly grouped into six groups: control, UCMS, WGE groups [5, 10, 20 mL WGE/kg body weight (bw) + UCMS], and a positive group (fluoxetine 20 mg/kg bw + UCMS). After four weeks of the UCMS paradigm, the sucrose preference, novel object recognition, and open field tests were conducted. The neurotransmitters serotonin (5-HT), dopamine (DA) and their metabolites were measured in the prefrontal cortex. Serum was collected to measure corticosterone and amyloid-42 (Aβ-42) levels. Feces were collected, and the gut microbiome was analyzed.

RESULTS

WGE restored sucrose preference, exploratory behavior, recognition ability, and decreased the levels of serum corticosterone and Aβ-42 in ApoE-/- mice to alleviate depressive-like behavior and cognitive impairment. Furthermore, WGE regulated the monoamine neurotransmitter via reduced the 5-HT and DA turnover rates in the prefrontal cortex. Moreover, WGE elevated the levels of potentially beneficial bacteria such as Bifidobacterium, Akkermansia, Alloprevotella, Defluviitaleaceae_UCG-011, and Bifidobacterium pseudolongum as well as balanced fecal short-chain fatty acids (SCFAs).

CONCLUSION

WGE demonstrates anti-depressive-like effects, cognitive impairment alleviation, and gut microbiome and metabolite regulation in ApoE-/- mice. Our results support the possibility of developing a functional and complementary medicine to prevent or alleviate depression and cognitive decline using WGE in CVDs patients.

Protective effect of Gastrodia elata blume ameliorates simulated weightlessness-induced cognitive impairment in mice

During the long-term orbital flight, exposure to microgravity negatively affects the astronauts' development of cognition, characterized by learning and memory decline. Gastrodia elata Blume (GEB) has a significant protective effect on cognitive impairment and has been used in Asia for centuries as a functional product. A previous study demonstrated that GEB could improve memory loss in mice caused by circadian rhythm disorders. However, the effects of GEB on cognitive dysfunction caused by weightless environments have not been investigated. In this study, mice received daily treatment with GEB (0.5, 1 g·kg^-1d^-1, i.g) and Huperzine A(Hup, 0.1 mg·kg^-1d^-1, i.g) orally until the end of the behavioral test (New object recognition test (NORT). Malondialdehyde (MDA) and nitric oxide (NO) levels were detected by kits, and expression of brain-derived neurotrophic factor (BDNF), protein kinase B (AKT), phosphorylated Akt (P-AKT), synaptophysin (SYN) and postsynaptic density 95(PSD95) in hippocampus were detected by western blotting. The results show that administration of GEB (0.5, 1 g·kg^-1d^-1, i.g) and Hup (0.1 mg·kg^-1d^-1, i.g) remarkably reverse HLS-induced learning and behavioral memory disorders, which were associated with significant changes in MDA and NO levels. Additionally, the protein expressions of BDNF, P-AKT/AKT, SYN, and PSD95 were significantly increased in the hippocampus. In summary, our findings will improve the reference for developing GEB as a functional product that improves memory decline.

An exploration of mechanism of high quality and yield of Gastrodia elata Bl. f. glauca by the isolation, identification and evaluation of Armillaria

BACKGROUND

Gastrodia elata Bl. f. glauca, a perennial herb of G.elata Bl. in Orchidaceae, is one of the most valuable traditional Chinese medicines. G. elata Bl. is a chlorophyll-free myco-heterotrophic plant, which must rely on the symbiotic growth of Armillaria, but not all Armillaria strains can play the symbiotic role. Additionally, Armillaria is easy to degenerate after multiple generations, and the compatibility between the strains from other areas and G. elata Bl. f. glauca in Changbai Mountain is unstable. Therefore, it is incredibly significant to isolate, identify and screen the symbiotic Armillaria suitable for the growth of G. elata Bl. f. glauca in Changbai Mountain, and to explore the mechanism by which Armillaria improves the production performance of G. elata Bl. f. glauca.

RESULTS

Firstly, G. elata Bl. f. glauca tubers, and rhizomorphs and fruiting bodies of Armillaria were used for the isolation and identification of Armillaria. Five Armillaria isolates were obtained in our laboratory and named: JMG, JMA, JMB, JMC and JMD. Secondly, Armillaria was selected based on the yield and the effective component content of G. elata Bl. f. glauca. It was concluded that the yield and quality of G. elata Bl. f. glauca co-planted with JMG is the highest. Finally, the mechanism of its high quality and yield was explored by investigating the effects of different Armillaria strains on the soil, its nutrition element contents and the soil microbial diversity around G. elata Bl. f. glauca in Changbai Mountain.

CONCLUSIONS

Compared with commercial strains, JMG significantly increased the content of Na, Al, Si, Mn, Fe, Zn, Rb and the absorption of C, Na, Mg, Ca, Cr, Cu, Zn and Rb in G. elata Bl. f. glauca; it improved the composition, diversity and metabolic functions of soil microbial communities around G. elata Bl. f. glauca at phylum, class and genus levels; it markedly increased the relative abundance of bacteria such as Chthoniobacter and Armillaria in the dominant populations, and enhanced such functions as Cell motility, amino acid metabolism and Lipid metabolism; it dramatically decreased the relative abundance of Bryobacter and other fungi in the dominant populations, and reduced such functions as microbial energy metabolism, translation and carbohydrate metabolism. This is the main reason why excellent Armillaria strains promote the high quality and yield of G. elata Bl. f. glauca in Changbai Mountain.

The effects of fresh Gastrodia elata Blume on the cognitive deficits induced by chronic restraint stress

Chronic restraint stress (CRS) is a classic animal model of stress that can lead to various physiological and psychological dysfunctions, including systemic neuroinflammation and memory deficits. Fresh Gastrodia elata Blume (FG), the unprocessed raw tuber of Gastrodia elata Blume, has been reported to alleviate the symptoms of headache, convulsions, and neurodegenerative diseases, while the protective effects of FG on CRS-induced cognitive deficits remain unclear. This work aimed to evaluate the effects of FG on CRS-induced cognitive deficits through multiplex animal behavior tests and to further explore the related mechanism by observing the expression of mitochondrial apoptosis-related proteins in the mouse hippocampus. In in vivo experiments, mice were subjected to the object location recognition test (OLRT), new object recognition test (NORT), Morris water maze test (MWMT), and passive avoidance test (PAT) to evaluate the learning and memory ability. In in vitro experiments, the expression of the AKT/CREB pathway, the fission- and apoptosis-related proteins (Drp1, Cyt C, and BAX), and the proinflammatory cytokines’ (TNF‐α and IL‐1β) level in the hippocampus was examined. Our results demonstrated that in spontaneous behavior experiments, FG significantly improved the cognitive performance of CRS model mice in OLRT (p < 0.05) and NORT (p < 0.05). In punitive behavior experiments, FG shortened the escape latency in long-term spatial memory test (MWMT, p < 0.01) and prolonged the latency into the dark chamber in non-spatial memory test (PAT, p < 0.01). Biochemical analysis showed that FG treatment significantly suppressed CRS‐induced Cyt C, Drp1, and BAX activation (p < 0.001, p < 0.01 and p < 0.05), promoted the CREB, p-CREB, AKT, and p-AKT level (p < 0.05, p < 0.01 and p < 0.001), and inhibited the CRS‐induced proinflammatory cytokines (TNF‐α and IL‐1β, p < 0.05 and p < 0.001) level in the hippocampus. Taken together, these results suggested that FG could attenuate cognitive deficits induced by CRS on multiple learning and memory behavioral tests.

Comparison on Bioactivities and Characteristics of Polysaccharides From Four Varieties of Gastrodia elata Blume

The composition, physicochemical properties, in vitro biological activity, and hypoglycemic activity exhibited by polysaccharides from four varieties of G. elata were investigated in this study; the four extracted GaE polysaccharides were termed as GaE-B (G. elata Bl. f. glauca S. chow polysaccharides), GaE-R (G. elata Bl. f. elata polysaccharides), GaE-Hyb (hybridization of G. elata Bl. f. glauca S. chow and G. elata Bl. f. elata polysaccharides), and GaE-G (G. elata Bl. f. viridis Makino polysaccharides). As revealed by the results, the GaE polysaccharides were found with the same monosaccharide composition, primarily including glucose, whereas the content of each variety was significantly different. In addition, different degrees of differences were found in the in vitro antioxidant and hypoglycemic activity, molecular weight, yield, and chemical composition exhibited by the abovementioned varieties. However, GaE-B and GaE-Hyb were found with similar physical properties, chemical composition, and antioxidant and hypoglycemic activity. GaE-R had the lowest yield, total sugar content, and molecular weight, whereas it involved higher xylose, binding protein, and polyphenols as well as higher antioxidant and hypoglycemic activity. In contrast, GaE-G was found with the highest yield, total sugar content, and molecular weight, whereas it contained the lowest xylose, binding protein, and polyphenols, as well as the weakest antioxidant and hypoglycemic activity. In brief, the polysaccharide of G. elata, a plant resource for homology of medicine and food, could more significantly enhance the biological activity of G. elata as it was released in the process of decocting and stewing. To be specific, the assessment of polysaccharide activity alone suggested that GaE-R was the best.

Application of the adverse outcome pathway concept for investigating developmental neurotoxicity potential of Chinese herbal medicines by using human neural progenitor cells in vitro

Adverse outcome pathways (AOPs) are organized sequences of key events (KEs) that are triggered by a xenobiotic-induced molecular initiating event (MIE) and summit in an adverse outcome (AO) relevant to human or ecological health. The AOP framework causally connects toxicological mechanistic information with apical endpoints for application in regulatory sciences. AOPs are very useful to link endophenotypic, cellular endpoints in vitro to adverse health effects in vivo. In the field of in vitro developmental neurotoxicity (DNT), such cellular endpoints can be assessed using the human "Neurosphere Assay," which depicts different endophenotypes for a broad variety of neurodevelopmental KEs. Combining this model with large-scale transcriptomics, we evaluated DNT hazards of two selected Chinese herbal medicines (CHMs) Lei Gong Teng (LGT) and Tian Ma (TM), and provided further insight into their modes-of-action (MoA). LGT disrupted hNPC migration eliciting an exceptional migration endophenotype. Time-lapse microscopy and intervention studies indicated that LGT disturbs laminin-dependent cell adhesion. TM impaired oligodendrocyte differentiation in human but not rat NPCs and activated a gene expression network related to oxidative stress. The LGT results supported a previously published AOP on radial glia cell adhesion due to interference with integrin-laminin binding, while the results of TM exposure were incorporated into a novel putative, stressor-based AOP. This study demonstrates that the combination of phenotypic and transcriptomic analyses is a powerful tool to elucidate compounds' MoA and incorporate the results into novel or existing AOPs for a better perception of the DNT hazard in a regulatory context.

Para-Hydroxybenzyl Alcohol Delays the Progression of Neurodegenerative Diseases in Models of Caenorhabditis elegans through Activating Multiple Cellular Protective Pathways

The traditional Chinese medicine Gastrodia elata (commonly called “Tianma” in Chinese) has been widely used in the treatment of rheumatism, epilepsy, paralysis, headache, and dizziness. Phenolic compounds, such as gastrodin, para-hydroxybenzyl alcohol (HBA), p-hydroxybenzaldehyde, and vanillin are the main bioactive components isolated from Gastrodia elata. These compounds not only are structurally related but also share similar pharmacological activities, such as antioxidative and anti-inflammatory activities, and effects on the treatment of aging-related diseases. Here, we investigated the effect of para-hydroxybenzyl alcohol (HBA) on neurodegenerative diseases and aging in models of Caenorhabditis elegans (C. elegans). Our results showed that HBA effectively delayed the progression of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease in models of C. elegans. In addition, HBA could increase the average lifespan of N2 worms by more than 25% and significantly improve the age-related physiological functions of worms. Moreover, HBA improved the survival rate of worms under stresses of oxidation, heat, and pathogenic bacteria. Further mechanistic investigation revealed that HBA could activate FOXO/DAF-16 and SKN-1 to regulate antioxidative and xenobiotic metabolism pathway. HBA could also activate HSF-1 to regulate proteostasis maintenance pathway, mitochondrial unfolded stress response, endoplasmic stress response and autophagy pathways. The above results suggest that HBA activated multiple cellular protective pathways to increase stress resistance and protect against aging and aging-related diseases. Overall, our study indicates that HBA is a potential candidate for future development of antiaging pharmaceutical application.

Gastrodia elata blume ameliorates circadian rhythm disorder-induced mice memory impairment

Circadian rhythm disorder (CRD) in space flight can lead to memory impairment, performance decrements and adverse health outcomes, the main manifestations of which are circadian desynchronization, sleep loss and insomnia. Sleep deprivation (SD) provide the means to evaluate these effects and the risks associated with CRD on ground. Gastrodia elata Blume (GEB) has beneficial effects on the treatment of sleep disturbances and memory loss. Fresh GEB (FG), an unprocessed raw tuber of GEB, has been used as functional health food in Asian countries for a long time. However, the research report of FG to ameliorate memory impairment caused by insomnia or lack of sleep is meager. In this study, ICR male mice were sleep-deprived continuously and water extract of FG (WFG) was orally administrated (3 and 9 g/kg/d, i.g) during the SD process lasted for 25 days, except control and model groups gavage administration with water, positive control group with modafinil (MOD, 0.1 g/kg/d, i.g). We studied the effect of WFG on CRD-induced learning and memory impairment using a set of behavioral analyses including the object location recognition test (OLRT), novel object recognition test (NORT), and the passive avoidance test (PAT). In addition, oxidative stress parameters were assessed by measuring the malondialdehyde (MDA) and superoxide dismutase (SOD) reactivity in serum and hippocampus. Our results revealed that SD decreased discrimination index (DI) in OLRT and NORT, with shorter latency into the dark chamber in PAT. Both WFG and MOD treatment can reverse these changes (P < 0.05). We concluded that WFG treatment improve CRD-induced learning and memory impairment and oxidative stress damage which makes FG a promising candidate as herbal health product of memory decline in CRD.

Towards a better understanding of the relationships between the structure and antitumor activity of Gastrodia elata polysaccharides by asymmetrical flow field-flow fractionation

To better understand the structure-function relationship of Gastrodia elata polysaccharides (PGEs), PGEs were extracted by ultrasound-assisted extraction method and the effects of extraction time on the structure and conformation of PGEs were evaluated by asymmetrical flow field-flow fractionation (AF4) coupled online with multiangle light scattering (MALS) and differential refractive index (dRI) detectors (AF4-MALS-dRI). Besides separation, AF4-MALS-dRI can provide more information about PGEs, such as size and molecular weight (M_w) distributions, apparent density, and conformation. The effects of PGEs on the proliferation, apoptosis, and cell cycle of MCF-7 cells were investigated. The cell activity assay indicated that the PGEs can inhibit the growth of MCF-7 cells by inducing late apoptosis. The results indicated that PGEs with a spherical conformation and compact structure seem to be beneficial to inducing MCF-7 cells late apoptosis. Moreover, results demonstrated that the information obtained by AF4-MALS-dRI is valuable for better understanding of the relationship of structure-activity of PGEs.

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

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

Gastrodia elata Blume water extract modulates neurotransmitters and alters the gut microbiota in a mild social defeat stress-induced depression mouse model

Gastrodia elata Blume has multiple bioactive functions, such as antioxidant and antidepressant activities, immune modulation, neuroplasticity, and neuroprotection. We previously found that the water extract of G. elata exerts antidepressant-like effects in unpredictable chronic mild stress models and animals exposed to the forced swimming test. We aimed to investigate the mechanisms by which the water extract of G. elata protects against subchronic- and mild-social defeat-stress-induced dysbiosis. After a 10-day subchronic and mild-social-defeat-stress program, oral treatment with the water extract of G. elata (500 mg/kg bw) resulted in reversal of depression-like behavior. In addition, monoamine analyses showed that the water extract of G. elata normalized the 5-hydroxyindoleacetic acid:5-HT ratio in the prefrontal cortex and colon and reduced the defeat-stress-induced kynurenine:tryptophan ratio in the colon. After the 10-day subchronic and mild social-defeat-stress program, the water extract of G. elata altered the intestinal microbiome by increasing Actinobacteria levels, modulating intestinal inflammation, and shifting the relative abundances of multiple bacterial groups in the gut. Our results suggest that the water extract of G. elata exhibits a potent antidepressant-like effect via the regulation of monoaminergic neurotransmission and alteration of gut microbiota composition and function, and that it may be an effective prevention for depression.

The antidepressant-like effects of Shen Yuan: Dependence on hippocampal BDNF-TrkB signaling activation in chronic social defeat depression-like mice

The Shen Yuan prescription (SY) comprises Panax ginseng (GT) and Polygala tenuifolia (YT), elicited superior antidepressant activity compared with that of GT or YT alone. The aim of this paper is to elucidate the effects of SY treatment on chronic social defeat stress (CSDS)-induced depression-like symptoms and the related mechanism. Our results indicated that SY treatment reverses the depressive-like behaviors induced by CSDS as measured by the social interaction test, sucrose preference test, forced swim test, and tail suspension test. SY decreased the serum levels of CORT and increased hippocampal neurotransmitters (5-HT, DA, and NE) in CSDS mice. Meanwhile, SY upregulated the brain-derived neurotrophic factor (BDNF) signaling pathway and reversed the decreased hippocampal neurogenesis caused by CSDS. In addition, we found that the TrkB antagonist K252a fully blocked the SY effects on behavioral improvement and eliminated the promoting effects of SY on hippocampal neurogenesis and BDNF-TrkB signaling (including the downstream ERK and Akt pathways) activation, thus further demonstrating that BDNF-TrkB signaling was necessary for the SY effects. In conclusion, our study showed that SY acted as an antidepressant in mice exhibiting CSDS-induced depression-like symptoms, and its effect was facilitated by promoting hippocampal neurogenesis and BDNF signaling pathway activation.

Gastrodiae Rhizoma Water Extract Ameliorates Hypothalamic-Pituitary-Adrenal Axis Hyperactivity and Inflammation Induced by Chronic Unpredictable Mild Stress in Rats

Gastrodiae Rhizoma is a highly valuable traditional herbal medicine commonly used to treat neurological disorders. The present study is designed to determine the antidepressant-like effect of the Gastrodiae Rhizoma water extract (GRWE) on a depression model and the potential mechanisms. The chronic unpredictable mild stress (CUMS) rat model was used to induce depression. The sucrose preference test, open field test, forced swimming test, and tail suspension test were performed to assess the depressive-like behaviors, respectively. Hypothalamic-pituitary-adrenal (HPA) function was measured via plasma corticosterone (CORT), adrenocorticotrophic hormone (ACTH), hypothalamic corticotropin-releasing factor (CRF), and glucocorticoid receptor (GR) concentrations. Plasma concentrations of proinflammatory cytokines including interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were also evaluated. The results showed that GRWE significantly attenuates the behavioral abnormalities in CUMS rats, as shown by elevated sucrose consumption, raised locomotor activity, and reduced immobility duration. Moreover, GRWE treatment reduced CORT, ACTH, CRF, and GR levels and decreased the plasma IL-1β, IL-6, and TNF-α concentrations. These findings indicate that GRWE improves depressive behaviors in a chronic stress model of rats; its effect may be ascribed to the modulation of the HPA axis activity and inflammatory response.

Glial Nrf2 signaling mediates the neuroprotection exerted by Gastrodia elata Blume in Lrrk2-G2019S Parkinson's disease

The most frequent missense mutations in familial Parkinson's disease (PD) occur in the highly conserved LRRK2/PARK8 gene with G2019S mutation. We previously established a fly model of PD carrying the LRRK2-G2019S mutation that exhibited the parkinsonism-like phenotypes. An herbal medicine, Gastrodia elata Blume (GE), has been reported to have neuroprotective effects in toxin-induced PD models. However, the underpinning molecular mechanisms of GE beneficiary to G2019S-induced PD remain unclear. Here, we show that these G2019S flies treated with water extracts of GE (WGE) and its bioactive compounds, gastrodin and 4-HBA, displayed locomotion improvement and dopaminergic neuron protection. WGE suppressed the accumulation and hyperactivation of G2019S proteins in dopaminergic neurons and activated the antioxidation and detoxification factor Nrf2 mostly in the astrocyte-like and ensheathing glia. Glial activation of Nrf2 antagonizes G2019S-induced Mad/Smad signaling. Moreover, we treated LRRK2-G2019S transgenic mice with WGE and found that the locomotion declines, the loss of dopaminergic neurons, and the number of hyperactive microglia were restored. WGE also suppressed the hyperactivation of G2019S proteins and regulated the Smad2/3 pathways in the mice brains. We conclude that WGE prevents locomotion defects and the neuronal loss induced by G2019S mutation via glial Nrf2/Mad signaling, unveiling a potential therapeutic avenue for PD.

Antidepressant-Like Effects of Ethanol Extract of Ziziphus jujuba Mill Seeds in Mice

The antidepressant-like activity of ethanol extract of Ziziphus jujuba Mill var. spinosa seeds (Semen Ziziphi Spinosae, SZS) was investigated by behavioral tests, such as a forced swimming test (FST), a tail-suspension test (TST), and an open field test (OFT), using mice exposed to chronic unpredictable mild stress (CUMS). In the TST, immobility times of the extract-treated groups E100 and E300 (CUMS + 100 and 300 mg/kg extract, respectively) were significantly decreased in a dose-dependent manner compared with the negative control (CUMS; p < 0.01, though those of E100 and E300 were higher than those of the positive control (CUMS + 15 mg/kg fluoxetine). In the FST, immobility times of E100 and E300 were decreased compared to the normal control. In the OFT, total and zone distances of E100 and E300 were significantly higher than those of negative controls (p < 0.01) with a dose dependency. In liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis after behavioral tests, norepinephrine (NE) and 5-hydroxytryptamine (5-HT) levels in the hippocampus tissues of E100 and E300 were significantly higher than those of negative controls. Brain-derived neurotrophic factor (BDNF) levels in the hippocampus tissues of E100 and E300 were higher than those of negative controls. From these results, the SZS ethanol extract exhibited significant antidepressant-like effects via immobility decrease, distance increase, hippocampal NE and 5-HT increase, and BDNF expression. These results suggest that the extract could be a potential antidepressant agent.

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.

Transcriptome analysis reveals underlying immune response mechanism of fungal (Penicillium oxalicum) disease in Gastrodia elata Bl. f. glauca S. chow (Orchidaceae)

BACKGROUND

Gastrodia elata Bl. f. glauca S. Chow is a medicinal plant. G. elata f. glauca is unavoidably infected by pathogens in their growth process. In previous work, we have successfully isolated and identified Penicillium oxalicum from fungal diseased tubers of G. elata f. glauca. As a widespread epidemic, this fungal disease seriously affected the yield and quality of G. elata f. glauca. We speculate that the healthy G. elata F. glauca might carry resistance genes, which can resist against fungal disease. In this study, healthy and fungal diseased mature tubers of G. elata f. glauca from Changbai Mountain area were used as experimental materials to help us find potential resistance genes against the fungal disease.

RESULTS

A total of 7540 differentially expressed Unigenes (DEGs) were identified (FDR < 0.01, log2FC > 2). The current study screened 10 potential resistance genes. They were attached to transcription factors (TFs) in plant hormone signal transduction pathway and plant pathogen interaction pathway, including WRKY22, GH3, TIFY/JAZ, ERF1, WRKY33, TGA. In addition, four of these genes were closely related to jasmonic acid signaling pathway.

CONCLUSIONS

The immune response mechanism of fungal disease in G. elata f. glauca is a complex biological process, involving plant hormones such as ethylene, jasmonic acid, salicylic acid and disease-resistant transcription factors such as WRKY, TGA.

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.

Farnesoid X Receptor-Mediated Cytoplasmic Translocation of CRTC2 Disrupts CREB-BDNF Signaling in Hippocampal CA1 and Leads to the Development of Depression-Like Behaviors in Mice

BACKGROUND

We recently identified neuronal expression of farnesoid X receptor (FXR), a bile acid receptor known to impair autophagy by inhibiting cyclic adenosine monophosphate response element-binding protein (CREB), a protein whose underfunctioning is linked to neuroplasticity and depression. In this study, we hypothesize that FXR may mediate depression via a CREB-dependent mechanism.

METHODS

Depression was induced in male C57BL6/J mice via chronic unpredictable stress (CUS). Subjects underwent behavioral testing to identify depression-like behaviors. A variety of molecular biology techniques, including viral-mediated gene transfer, Western blot, co-immunoprecipitation, and immunofluorescence, were used to correlate depression-like behaviors with underlying molecular and physiological events.

RESULTS

Overexpression of FXR, whose levels were upregulated by CUS in hippocampal CA1, induced or aggravated depression-like behaviors in stress-naïve and CUS-exposed mice, while FXR short hairpin RNA (shRNA) ameliorated such symptoms in CUS-exposed mice. The behavioral effects of FXR were found to be associated with changes in CREB-brain-derived neurotrophic factor (BDNF) signaling, as FXR overexpression aggravated CUS-induced reduction in BDNF levels while the use of FXR shRNA or disruption of FXR-CREB signaling reversed the CUS-induced reduction in the phosphorylated CREB and BDNF levels. Molecular analysis revealed that FXR shRNA prevented CUS-induced cytoplasmic translocation of CREB-regulated transcription coactivator 2 (CRTC2); CRTC2 overexpression and CRTC2 shRNA abrogated the regulatory effect of FXR overexpression or FXR shRNA on CUS-induced depression-like behaviors.

CONCLUSIONS

In stress conditions, increased FXR in the CA1 inhibits CREB by targeting CREB and driving the cytoplasmic translocation of CRTC2. Uncoupling of the FXR-CREB complex may be a novel strategy for depression treatment.

Three new compounds from the flower branch of Gastrodia elata Blume and anti-microbial activity

Three new compounds (1–3): gastrodinol (1), 2-(4′-hydroxybenzoyl)-3-hydroxyethyl indole (2) and 2-(4′-hydroxybenzoyl)-3-(4′′-hydroxybenzyl)indole (3) were isolated from the flower branch of G. elata, and anti-microbial activity.

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.

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

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

Antidepressant-Like and Neuroprotective Effects of Ethanol Extract from the Root Bark of Hibiscus syriacus L

Hibiscus syriacus L. (Malvaceae) is an important ornamental shrub in horticulture and has been widely used as a medical material in Asia. The aim of this study was to assess the antidepressant and neuroprotective effects of a root bark extract of H. syriacus (HSR) and to investigate the underlying molecular mechanisms. Using an animal model of restraint stress, we investigated the effects of HSR on depressive-like behaviors and on the expression levels of serotonin, corticosterone, and neurotrophic factors in the brain. The mice were exposed to restraint stress for 2 h per day over a period of 3 weeks and orally treated with HSR (100, 200, or 400 mg/kg/day). We also examined the neuroprotective effect of HSR using corticosterone-treated human neuroblastoma SK-N-SH cells. The cells were incubated with the extract for 24 h, followed by corticosterone stimulation for 1 h, and then cell viability assay, cellular ATP assay, mitochondrial membrane potential (MMP) assay, cellular reactive oxygen species (ROS) assay, and western blotting were used to investigate the neuroprotective effects of HSR. Administration of HSR not only reduced the immobility times of the restraint-stressed mice in the forced swimming and tail suspension tests, but also significantly increased sucrose preference in the sucrose preference test. In addition, HSR significantly reduced the plasma levels of corticosterone and increased the brain levels of serotonin. The extract also increased the phosphorylation level of cyclic AMP response element-binding (CREB) protein and the expression level of brain-derived neurotrophic factor (BDNF). The in vitro assays showed that HSR pretreatment increased cell viability and ATP levels, recovered MMP, decreased ROS levels, and increased the expression of CREB and BDNF in corticosterone-induced neurotoxicity. Taken together, our data suggest that HSR may have the potential to control neuronal cell damage and depressive behaviors caused by chronic stress.

Apelin-13 reverses memory impairment and depression-like behavior in chronic social defeat stressed rats

The apelin/APJ signaling is composed of the short peptide apelin usually including apelin-13, apelin-17 and apelin-36, and its receptor APJ. This signaling is abundantly expressed in limbic structures such as the hippocampus, suggesting a potential role in stress response and learning and memory. We recently reported that apelin-13 reverses acute stress-induced memory impairment and depression-like behavior in rats. Here, we further investigate whether apelin-13 reverses memory impairment and depression-like behavior in chronic stressed rats. Rats were subjected to chronic social defeat stress (CSDS), and received intracerebroventricular infusion of apelin-13 for one week after stress withdrawal. Behavioral test battery was performed to assess memory performance and depression-like behavior. Results showed that apelin-13 reversed CSDS-induced decrease in the alternation ratio and discrimination index in the Y-maze and novel object recognition tests, respectively. Apelin-13 also reversed CSDS-induced social avoidance in the social interaction test, and behavioral despair in the forced swimming and tail suspension tests. Additionally, apelin-13 did not influence locomotor activity in the open field test. These observations suggest that apelin-13 reverses memory impairment and depression-like behavior in chronic stressed rats.