Gastrodin protect primary cultured rat hippocampal neurons against amyloid-beta peptide-induced neurotoxicity via ERK1/2-Nrf2 pathway

Piper betle Induced Cytoprotective Genes and Proteins via the Nrf2/ARE Pathway in Aging Mice

BACKGROUND/AIMS

The objective of this study was to elucidate the underlying antioxidant mechanism of aqueous extract of Piper betle (PB) in aging rats. The nuclear factor erythroid 2-related factor 2 (Nrf2)/ARE pathway involving phase II detoxifying and antioxidant enzymes plays an important role in the antioxidant system by reducing electrophiles and reactive oxygen species through induction of phase II enzymes and proteins.

METHODS

Genes and proteins of phase II detoxifying antioxidant enzymes were analyzed by QuantiGenePlex 2.0 Assay and Western blot analysis.

RESULTS

PB significantly induced genes and proteins of phase II and antioxidant enzymes, NAD(P)H quinone oxidoreductase 1, and catalase in aging mice (p < 0.05). The expression of these enzymes were stimulated via translocation of Nrf2 into the nucleus, indicating the involvement of ARE, a cis-acting motif located in the promoter region of nearly all phase II genes.

CONCLUSIONS

PB was testified for the first time to induce cytoprotective genes through the Nrf2/ARE signaling pathway, thus unraveling the antioxidant mechanism of PB during the aging process.

Gastrodin Attenuates Pentylenetetrazole-Induced Seizures by Modulating the Mitogen-Activated Protein Kinase-Associated Inflammatory Responses in Mice

Gastrodin, the major component isolated from the rhizome of the Chinese traditional medicinal herb Gastrodia elata ("Tianma"), has a long history in the treatment of epilepsy and other neurological disorders. However, the molecular mechanisms are not clear. Here, we found that gastrodin ameliorated pentylenetetrazole (PTZ)-induced epileptic seizures with improvement of the electroencephalographic pattern in mice. Further studies demonstrated that gastrodin decreased the levels of the pro-inflammatory cytokines interleukin-1β and tumor necrosis factor-α while increasing interleukin-10, an anti-inflammatory cytokine in the brain. Furthermore, gastrodin attenuated the PTZ-induced microglial activation along with inhibition of mitogen-activated protein kinases, cAMP response element binding protein, and NF-κB. Our data suggest that gastrodin attenuates seizures by modulating the mitogen-activated protein kinase-associated inflammatory responses.

Proliferation-enhancing effects of gastrodin on RSC96 Schwann cells by regulating ERK1/2 and PI3K signaling pathways

The proliferation and migration of Schwann cells (SCs) are essential in the process of peripheral nerve repair. A large amount of studies focused on the promotion of the growth of SCs for cell based therapy. Gastrodin (GAS), the main constituent of a Chinese traditional herbal medicine named Gastrodia elata Blume, has been reported to be associated with neuroprotective properties. Besides, GAS activated MAPK and PI3K signaling pathways which are often involved in growth of nerve cells were also reported. Based on the hypothesis that GAS may have an effect on SCs growth, we studied the effect of GAS on rat RSC96 Schwann cells (SCs) and further explored the underlying mechanism. Various concentration of GAS (0μM, 50μM, 100μM, and 200μM) was used for treatment of RSC96 SCs, with the cell proliferation and gene expression of several neurotrophic factors to be detected. Regulation of MAPK and PI3K signaling pathways were assayed by detecting phosphorylation of ERK1/2 and Akt. The results showed that GAS could effectively promote proliferation of RSC96 SCs in a dose- and time-dependent manner. The best performance was obtained at the concentration of 200μM. Exploration of the underlying mechanism showed that GAS probably affects SCs metabolism through inhibiting ERK1/2 phosphorylation and activating Akt phosphorylation in RSC96 SCs. This study may provide reference for its application in treatment of peripheral nerve injuries.

Gastrodin reversed the traumatic stress-induced depressed-like symptoms in rats

Exposure to severe stress can lead to the development of neuropsychiatric disorders such as depression and post-traumatic stress disorder (PTSD) in at-risk individuals. Gastrodin (GAS), a primary constituent of an Oriental herbal medicine, has been shown to effectively treat various mood disorders. Thus, the present study aimed to determine whether GAS would ameliorate stress-associated depression-like behaviors in a rat model of single prolonged stress (SPS)-induced PTSD. Following the SPS procedure, rats received intraperitoneal administration of GAS (20, 50, or 100 mg/kg) once daily for 2 weeks. Subsequently, the rats performed the forced swimming test, and norepinephrine (NE) levels in the hippocampus were measured. Daily GAS (100 mg/kg) significantly reversed depression-like behaviors and restored SPS-induced increases in hippocampal NE concentrations as well as tyrosine hydroxylase expression in the locus coeruleus. Furthermore, the administration of GAS attenuated SPS-induced decreases in the hypothalamic expression of neuropeptide Y and the hippocampal mRNA expression of brain-derived neurotrophic factor. These findings indicate that GAS possesses antidepressant effects in the PTSD and may be an effective herbal preparation for the treatment of PTSD.

Gastrodin Protects Neural Progenitor Cells Against Amyloid β (1-42)-Induced Neurotoxicity and Improves Hippocampal Neurogenesis in Amyloid β (1-42)-Injected Mice

The aim of this study was to investigate the neuroprotective effects of gastrodin (GAS), one of the major bioactive components of Gastrodia elata Blume (Tian Ma), against amyloid β (Aβ) (1-42)-induced neurotoxicity in primary neural progenitor cells (NPCs). We found that pretreatment with GAS not only prevents a loss in cell viability following treatment with Aβ (1-42) but also counteracts Aβ (1-42)-triggered release of pro-inflammatory cytokines and nitric oxide (NO) in a dose-dependent manner. Additionally, GAS was able to attenuate Aβ (1-42)-induced apoptosis in NPCs, evidenced by the decreased percentage of apoptotic cells and altered expression of apoptosis-related proteins in response to GAS pretreatment prior to Aβ (1-42) exposure. Furthermore, in Aβ (1-42)-injected C57BL/6 mice, we found that systemic administration of GAS could improve hippocampal neurogenesis, manifested by the increased number of SOX-2 and doublecortin (DCX)-positive cells in the DG area. Mechanistic studies revealed that in NPCs, GAS could reverse the Aβ (1-42)-induced increase in phosphorylation of MEK-1/2, extracellular signal-regulated kinases (ERK), and c-Jun N-terminal kinase (JNK). When combining GAS with the MEK inhibitor U0126 or the JNK inhibitor SP600125, we observed a synergistic effect against Aβ (1-42)-induced reduction in cell viability of NPCs. Taken together, these results show the efficacy and underlying mechanism of GAS against amyloid β (1-42)-induced neurotoxicity and provide substantial insight into the potential merits of GAS for its clinical application in the treatment of Alzheimer's disease.

Gastrodin suppresses BACE1 expression under oxidative stress condition via inhibition of the PKR/eIF2α pathway in Alzheimer's disease

The expression of β-site APP-cleaving enzyme 1 (BACE1) is increased in the brain of late-onset sporadic Alzheimer's disease (AD) and oxidative stress may be the potential cause of this event. The phenolic glucoside gastrodin (Gas), a main component of a Chinese herbal medicine Gastrodia elata Blume, has been demonstrated to display antioxidant activity and suppresses BACE1 expression. However, the mechanisms by which Gas suppresses BACE1 expression are not clear. Morris water maze test was performed to assess the effect of Gas treatment on memory impairments in Tg2576 mice. The level of oxidative stress in the brain of Tg2576 mice was determined by measuring the superoxide dismutase (SOD) activity, catalase (CAT) activity, and the levels of malondialdehyde (MDA) and ROS. In vivo and in vitro, we detected the expression levels of BACE1, pPKRThr446, PKR, pPERKThr981, PERK, peIF2αSer51, and eIF2α using western blot analysis. We found that Gas improved learning and memory abilities of Tg2576 transgenic mice and attenuated intracellular oxidative stress in hippocampi of Tg2576 mice. We discovered that the expression levels of BACE1, activated PKR (pPKRThr446) and activated eIF2α (peIF2αSer51) were elevated in the brains of Tg2576 mice and hydrogen peroxide (H2O2)-stimulated SH-SY5Y cells. Moreover, peptide PKR inhibitor (PRI) and Gas down-regulated BACE1 expression in Tg2576 mice and H2O2-stimulated SH-SY5Y cells by inhibiting activation of PKR and eIF2α. Gas alleviates memory deficits in mice and suppresses BACE1 expression by inhibiting the protein kinase/Eukaryotic initiation factor-2α (PKR/eIF2α) pathway. The research suggested that Gas may develop as an drug candidate in neurodegenerative diseases.

Protective Effects of Gastrodin Against Autophagy-Mediated Astrocyte Death

Gastrodin is an active ingredient derived from the rhizome of Gastrodia elata. This compound is usually used to treat convulsive illness, dizziness, vertigo, and headache. This study aimed to investigate the effect of gastrodin on the autophagy of glial cells exposed to lipopolysaccharides (LPS, 1 µg/mL). Autophagy is a form of programmed cell death, although it also promotes cell survival. In cultured astrocytes, LPS exposure induced excessive autophagy and apoptosis, which were significantly prevented by the pretreatment cells with gastrodin (10 μM). The protective effects of gastrodin via autophagy inhibition were verified by the decreased levels of LC3-II, P62, and Beclin-1, which are classical markers for autophagy. Furthermore, gastrodin protected astrocytes from apoptosis through Bcl-2 and Bax signaling pathway. The treatment of astrocytes with rapamycin (500 nM), wortmannin (100 nM), and LY294002 (10 μM), which are inhibitors of mTOR and PI3K, respectively, eliminated the known effects of gastrodin on the inhibited Beclin-1 expression. Furthermore, gastrodin blocked the down-regulation of glutamine synthetase induced by LPS exposure in astrocytes. Our results suggest that gastrodin can be used as a preventive agent for the excessive autophagy induced by LPS.

Gastrodin Ameliorates Oxidative Stress and Proinflammatory Response in Nonalcoholic Fatty Liver Disease through the AMPK/Nrf2 Pathway

This study was designed to investigate the antioxidative, antiinflammatory and metabolism-regulating effects of gastrodin (GSTD) in the treatment of nonalcoholic fatty liver disease (NAFLD). Oleic acid (OA) was used to induce steatosis in HL-7702 cells; a high-fat or high-fat and high-cholesterol diet was used to induce NAFLD in mice and rats. Our results showed that GSTD significantly increased hepatic superoxide dismutase (SOD) but decreased reactive oxygen species (ROS)/malondialdehyde (MDA) and reduced the mRNA levels of proinflammatory cytokines both in vitro and in vivo. GSTD promoted the phosphorylation of nuclear factor erythroid-2-related factor-2 (Nrf2) at serine (Ser) 40, stimulated its nuclear translocation and increased hepatic expression of heme oxygenase-1 (HO-1). GSTD activated AMP-activated protein kinase (AMPK), suppressed hepatic steatosis, lowered serum triglyceride (TG)/glucose and decreased body weight gain in animals with NAFLD. The stimulating effects of GSTD on the Nrf2 pathway as well as its antioxidative/antiinflammatory activities were abolished by compound C in OA-treated HL-7702 cells. In summary, our results demonstrate that GSTD activates the AMPK/Nrf2 pathway, ameliorates oxidative stress/proinflammatory response and improves lipid metabolism in NAFLD. Our findings may support the future clinical application of GSTD for the treatment of NAFLD to reduce hepatic steatosis, oxidative stress and proinflammatory response.

4-Hydroxybenzyl-substituted amino acid derivatives from Gastrodia elata

Seven new 4-hydroxybenzyl-substituted amino acid derivatives (1−7), together with 11 known compounds, were isolated from an aqueous extract of the rhizomes of Gastrodia elata Blume. Their structures were determined by spectroscopic and chemical methods. Compounds 1−3 are pyroglutamate derivatives containing 4-hydroxybenzyl units at the N atom and 4−7 are the first examples of natural products with the 4-hydroxybenzyl unit linked via a thioether bond to 2-hydroxy-3-mercaptopropanoic acid (4−6) and 2-hydroxy-4-mercaptobutanoic acid (7), which would be biogenetically derived from cysteine and homocysteine, respectively. The structures of 1 and 2 were verified by synthesis, while the absolute configurations of 4, 5 and 7 were assigned using Mosher’s method based on the MPA determination rule of Δδ_RS values. The known compound 4-(hydroxymethyl)-5-nitrobenzene-1,2-diol (8) exhibited activity against Fe²⁺-cysteine induced rat liver microsomal lipid peroxidation with IC₅₀ values of 9.99×10⁻⁶ mol/L.

Prolonged oral administration of Gastrodia elata extract improves spatial learning and memory of scopolamine-treated rats

Gastrodia elata (GE) is traditionally used for treatment of various disorders including neurodegenerative diseases such as Alzheimer's disease. To investigate the neuroprotective effect of GE, amyloid-β peptide (Aβ)-treated PC12 cells were cultured with GE aqueous extract. In vitro assay demonstrated that 50 µM of pre-aggregated Aβ was lethal to about a half portion of PC12 cells and that Aβ aggregate-induced cell death was significantly decreased with GE treatment at ≤10 mg/mL in a dose-dependent manner. To further examine in vivo cognitive-improving effects, an artificial amnesic animal model, scopolamine-injected Sprague-Dawley rats, were orally administered the extract for 6 weeks followed by behavioral tests (the passive avoidance test and Morris water maze test). The results showed that an acute treatment with scopolamine (1 mg/kg of body weight) effectively induced memory impairment in normal rats and that the learning and memory capability of scopolamine-treated rats improved after prolonged administration of GE extract (50, 250 and 500 mg/kg of body weight for 6 weeks). These findings suggest that a GE regimen may potentially ameliorate learning and memory deficits and/or cognitive impairments caused by neuronal cell death.

Partridgeberry polyphenols protect primary cortical and hippocampal neurons against β-amyloid toxicity

β-Amyloid (Aβ) deposition elicits a toxic effect on neurons and plays a crucial role in the etiology and/or progression of Alzheimer's disease (AD). Polyphenols found in fruits are endorsed for nutritional intervention in AD, since they are known to have extensive therapeutic properties apropos of brain health owing to their anti-oxidative effects against Aβ and neural reactive oxygen species (ROS). The present study was aimed to investigate the neuroprotective potential of polyphenols of partridgeberry (Vaccinium vitis-idaea L.) and elucidate the mechanism by which they confer protection against Aβ toxicity in rat primary neurons in vitro. The pre-treatment of rat primary cortical and hippocampal neurons with partridgeberry polyphenols (10-200μgmL^-1) significantly attenuated Aβ-induced cell death and membrane damage. The flavan-3-ol- and flavonol-rich fractions of the partridgeberry exhibited the strongest ability to maintain cell viability (EC₅₀ 5.9μgmL^-1) and prevent lactose dehydrogenase release (IC₅₀ 0.01μgmL^-1) (P≤0.05). Similar to the maintenance of cellular viability, the flavan-3-ol- and flavonol-rich fractions also amplified the greatest activity of SOD and catalase among all polyphenol preparations exposed to neurons (P≤0.05). All four partridgeberry polyphenol preparations reduced the intracellular Aβ levels by 7-15 folds, and initiated Aβ clearance from neurons as compared to untreated cells (P≤0.05). Partridgeberry derived polyphenol preparations; especially the flavonol-rich fraction (IC₅₀ 97.1μgmL^-1) significantly modulated the apoptotic targets and in vitro acetylcholinesterase activity (P≤0.05), indicating potential pharmacotherapy application in AD. Furthermore, the restoration of hyperactive caspases and Bcl2 family of apoptotic architects added to the neuroprotective candidacy of PPFs. These findings suggest that partridgeberry polyphenols, especially flavan-3-ol- and flavonol-rich fractions, could be of importance in prevention and/or treatment of AD.

Neurohormetic phytochemicals: An evolutionary-bioenergetic perspective

The impact of dietary factors on brain health and vulnerability to disease is increasingly appreciated. The results of epidemiological studies, and intervention trials in animal models suggest that diets rich in phytochemicals can enhance neuroplasticity and resistance to neurodegeneration. Here we describe how interactions of plants and animals during their co-evolution, and resulting reciprocal adaptations, have shaped the remarkable characteristics of phytochemicals and their effects on the physiology of animal cells in general, and neurons in particular. Survival advantages were conferred upon plants capable of producing noxious bitter-tasting chemicals, and on animals able to tolerate the phytochemicals and consume the plants as an energy source. The remarkably diverse array of phytochemicals present in modern fruits, vegetables spices, tea and coffee may have arisen, in part, from the acquisition of adaptive cellular stress responses and detoxification enzymes in animals that enabled them to consume plants containing potentially toxic chemicals. Interestingly, some of the same adaptive stress response mechanisms that protect neurons against noxious phytochemicals are also activated by dietary energy restriction and vigorous physical exertion, two environmental challenges that shaped brain evolution. In this perspective article, we describe some of the signaling pathways relevant to cellular energy metabolism that are modulated by 'neurohormetic phytochemicals' (potentially toxic chemicals produced by plants that have beneficial effects on animals when consumed in moderate amounts). We highlight the cellular bioenergetics-related sirtuin, adenosine monophosphate activated protein kinase (AMPK), mammalian target of rapamycin (mTOR) and insulin-like growth factor 1 (IGF-1) pathways. The inclusion of dietary neurohormetic phytochemicals in an overall program for brain health that also includes exercise and energy restriction may find applications in the prevention and treatment of a range of neurological disorders.

Ameliorative effect of gastrodin on 3,3'-iminodipropionitrile-induced memory impairment in rats

3,3'-Iminodipropionitrile (IDPN), one of the nitrile derivatives inducing neurotoxicity, causes the dyskinetic syndrome and cognitive impairment. Gastrodin is widely used to treat neurological disorders and showed to improve cognitive functions. The present study aimed to determine whether treatment with gastrodin can attenuate IDPN-induced impairment of memory consolidation in the passive avoidance (PA) task, and to explore the possible neural mechanisms. Our results showed that intragastric administration of gastrodin (200mg/kg) reversed the IDPN-induced impairment of memory consolidation as indicated by the prolonged retention latency in the PA task. Furthermore, gastrodin reverted IDPN-induced reduction of serotonin (5-HT) and elevation of serotonin turnover ratio. Gastrodin treatment prevented the increase of serotonin transporter (SERT) and the decrease of serotonin 1A (5-HT1A) receptor expression in the hippocampus of IDPN-treated rats. These results suggest that long-term gastrodin treatment could represent a novel pharmacological strategy for IDPN-induced memory impairment, as well that its protective effect is mediated through normalization of the serotoninergic system.

Adaptive cellular stress pathways as therapeutic targets of dietary phytochemicals: focus on the nervous system

During the past 5 decades, it has been widely promulgated that the chemicals in plants that are good for health act as direct scavengers of free radicals. Here we review evidence that favors a different hypothesis for the health benefits of plant consumption, namely, that some phytochemicals exert disease-preventive and therapeutic actions by engaging one or more adaptive cellular response pathways in cells. The evolutionary basis for the latter mechanism is grounded in the fact that plants produce natural antifeedant/noxious chemicals that discourage insects and other organisms from eating them. However, in the amounts typically consumed by humans, the phytochemicals activate one or more conserved adaptive cellular stress response pathways and thereby enhance the ability of cells to resist injury and disease. Examplesof such pathways include those involving the transcription factors nuclear factor erythroid 2-related factor 2, nuclear factor-κB, hypoxia-inducible factor 1α, peroxisome proliferator-activated receptor γ, and forkhead box subgroup O, as well as the production and action of trophic factors and hormones. Translational research to develop interventions that target these pathways may lead to new classes of therapeutic agents that act by stimulating adaptive stress response pathways to bolster endogenous defenses against tissue injury and disease. Because neurons are particularly sensitive to potentially noxious phytochemicals, we focus on the nervous system but also include findings from other cell types in which actions of phytochemicals on specific signal transduction pathways have been more thoroughly studied.

Puerarin induces the upregulation of glutathione levels and nuclear translocation of Nrf2 through PI3K/Akt/GSK-3β signaling events in PC12 cells exposed to lead

Oxidative stress is thought to be involved in lead-induced toxicity, especially affecting the brain. We reported previously that puerarin possesses antioxidative properties in the nervous system. Therefore, the aim of the present study was to test the hypothesis that puerarin inhibits lead acetate-induced oxidative stress in PC12 cells by interrupting phosphatidylinositol-3 kinase (PI3K)/Akt signaling through increasing glutathione (GSH) synthesis. Our results showed that puerarin attenuates oxidative stress in a concentration-dependent manner in PC12 cells exposed to lead acetate demonstrated by scavenging reactive oxygen species (ROS) and reducing lipid peroxidation (LPO). Treatment with puerarin significantly up-regulates glutamate cysteine ligase catalytic subunit (GCLc) expression both at its mRNA and protein levels, but not glutamate cysteine ligase modifier (GCLm) subunit, accompanying the elevation of cellular glutathione level. The increased nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) was not because of increased transcription of Nrf2 as Nrf2 transcript levels did not change after puerarin treatment. The effects of puerarin could be partially blocked by pharmacologic inhibition of PI3K and the glycogen synthase kinase 3β (GSK-3β) pathways with LY294002 and LiCl, respectively. On the other hand, puerarin treatment promoted Akt and GSK-3β phosphorylation in PC12 cells exposed to lead acetate. Moreover, puerarin failed to modulate the phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), p-c-Jun N-terminal kinases (JNK), and p-p38 mitogen-activated protein kinase (MAPK) demonstrating some specificity for its action on the PI3K/GSK-3β pathway. These findings suggest that puerarin as a phytoestrogen might be an attractive agent for prevention and treatment of chronic diseases related to lead neurotoxicity.

Gastrodin suppresses the amyloid β-induced increase of spontaneous discharge in the entorhinal cortex of rats

Accumulated soluble amyloid beta- (Aβ-) induced aberrant neuronal network activity may directly contribute to cognitive deficits, which are the most outstanding characteristics of Alzheimer's disease (AD). The entorhinal cortex (EC) is one of the earliest affected brain regions in AD. Impairments of EC neurons are responsible for the cognitive deficits in AD. However, little effort has been made to investigate the effects of soluble Aβ on the discharge properties of EC neurons in vivo. The present study was designed to examine the effects of soluble Aβ₁₋₄₂ on the discharge properties of EC neurons, using in vivo extracellular single unit recordings. The protective effects of gastrodin (GAS) were also investigated against Aβ₁₋₄₂-induced alterations in EC neuronal activities. The results showed that the spontaneous discharge of EC neurons was increased by local application of soluble Aβ₁₋₄₂ and that GAS can effectively reverse Aβ₁₋₄₂-induced facilitation of spontaneous discharge in a concentration-dependent manner. Moreover, whole-cell patch clamp results indicated that the protective function of GAS on abnormal hyperexcitability may be partially mediated by its inhibitory action on Aβ₁₋₄₂-elicited inward currents in EC neurons. Our study suggested that GAS may provide neuroprotective effects on Aβ₁₋₄₂-induced hyperactivity in EC neurons of rats.

Gastrodin prevents motor deficits and oxidative stress in the MPTP mouse model of Parkinson's disease: involvement of ERK1/2-Nrf2 signaling pathway

AIMS

Current no effective therapy is available to halt the progression of Parkinson's disease (PD). Oxidative stress has been implicated in the etiology of PD. The present study evaluates the hypothesis that prevention of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced motor deficits by gastrodin might mainly result from its antioxidant property via interrupting extracellular signal regulated protein kinases (ERK) 1/2-nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway.

MAIN METHODS

Pretreatment of mouse model of PD is established by treating C57BL/6 mice with 4 doses of MPTP (30 mg/kg per day, i.p.), with gastrodin (60 mg/kg per day) administered by daily intraperitoneal injection for 2 weeks. Motor behavior of mice was monitored by open-field test and rotarod test. Real-time polymerase chain reaction and Western blotting were used to analyze the expression of genes.

KEY FINDINGS

MPTP-induced motor deficits were partially and significantly forestalled by gastrodin. Gastrodin treatment prevented MPTP-induced oxidative stress, as measured by malondialdehyde in midbrain. Interestingly, MPTP-intoxicated mice treated with gastrodin robustly increased heme oxygenase 1, superoxide dismutase, glutathione levels, and Nrf2 nuclear translocation in striatum of MPTP-intoxicated mice. Furthermore, results herein suggest that the antioxidant pathway activated by gastrodin involves ERK1/2 phosphorylation.

SIGNIFICANCE

Gastrodin protects midbrain of MPTP-intoxicated mice against oxidative stress, in part, through interrupting ERK1/2-Nrf2 pathway mechanism, which will give us an insight into the potential of gastrodin in terms of opening up new therapeutic avenues for PD.

Identification and analysis of gastrodin and its five metabolites using ultra fast liquid chromatography electrospray ionization tandem mass spectrometry to investigate influence of multiple-dose and food

A reliable and highly sensitive ultra performance liquid chromatography electrospray ionization tandem mass spectrometry (UFLC-ESI-MS/MS) analytical method was developed for identification and quantification of gastrodin (GAS) and its metabolites in rat plasma. Five metabolites were identified: p-formylphenyl-β-d-glucopyranoside (M1), p-hydroxybenzonic acid (M2), p-hydroxybenzyl alcohol (M3), p-formaldehydephenyl-β-d-glucopyranoside (M4), p-hydroxybenzaldehyde (M5). The molecular structures of metabolites were proposed based on the characters of their precursor ions, product ions and chromatographic retention time. Four of them were reported firstly in rat plasma. This method involved the addition of bergeninum as the internal standard (IS), UFLC separation, and quantification by MS/MS system using negative electrospray ionization in the multiple reaction monitoring (MRM) mode. The lower limit of quantification of gastrodin and five metabolites were all 1ng/mL. The method was linear in the concentration range of 0.001-10μg/mL. The intra- and inter-day precisions (R.S.D %) were within 15.0% for all analytes. No interference was noted due to endogenous substances. All analytes were stable in rat plasma stored at room temperature and 4°C for at least 4h, -20°C combined with three freeze-thaw cycles for at least 1 month. By this method, the influence of multiple-dose and food on the pharmacokinetics behaviors of GAS and its metabolites were studied for the first time. We hope pharmacokinetic data of present study may inspire rational clinical usage of GAS.

Gastrodin protects against MPP(+)-induced oxidative stress by up regulates heme oxygenase-1 expression through p38 MAPK/Nrf2 pathway in human dopaminergic cells

Although the etiology of PD remains unclear, increasing evidence has shown that oxidative stress plays an important role in its pathogenesis and that of other neurodegenerative disorders. The phenolic glucoside gastrodin, a main constituent of a Chinese herbal medicine Gastrodia elata (GE) Blume, has been known to display antioxidant activity. The present study aimed to investigate the protective effects of gastrodin on 1-methyl-4-phenylpyridinium (MPP(+))-induced oxidative cytotoxicity in human dopaminergic SH-SY5Y cells and the underlying mechanism for this neuroprotection. Results indicate that pre-treatment with gastrodin for 1h significantly reduced the MPP(+)-induced viability loss, apoptotic rate and attenuated MPP(+)-mediated ROS production. In addition, gastrodin inhibited MPP(+)-induced lowered membrane potential, decreased Bcl-2/Bax ratio. Moreover, we have revealed the gastrodin increased Nrf2 nuclear translocation, which is upstream of heme oxygenase-1 (HO-1) expression and for the first time revealed gastrodin could increased antioxidant enzyme HO-1 expression in concentration-dependent and time-dependent manners. HO-1 siRNA transfection was employed, and confirmed gastrodin could active the expression of HO-1. And the increase in HO-1 expression was correlated with the protective effect of gastrodin against MPP(+)-induced injury. Because the inhibitor of HO-1 activity, ZnPP reversed the protective effect of gastrodin against MPP(+)-induced cell death. We also demonstrated that the specific p38 MAPK inhibitor, SB203580, concentration-dependently blocked on gastrodin-induced HO-1 expression, and meanwhile SB203580 reversed the protective effect of gastrodin against MPP(+)-induced cell death. Taken together, these findings suggest that gastrodin can induce HO-1 expression through activation of p38 MAPK/Nrf2 signaling pathway, thereby protecting the SH-SY5Y cells from MPP(+)-induced oxidative cell death. Thus our study indicates that gastrodin has a partial cytoprotective role in dopaminergic cell culture systems and could be of importance for the treatment of PD and other oxidative stress-related diseases.

Gastrodin ameliorates memory deficits in 3,3'-iminodipropionitrile-induced rats: possible involvement of dopaminergic system

3,3'-Iminodipropionitrile (IDPN), one of the nitrile derivatives, can induce neurotoxicity, and therefore cause motor dysfunction and cognitive deficits. Gastrodin is a main bioactive constituent of a Chinese herbal medicine (Gastrodia elata Blume) widely used for treating various neurological disorders and showed greatly improved mental function. This study was designed to determine whether administration of gastrodin attenuates IDPN-induced working memory deficits in Y-maze task, and to explore the underlying mechanisms. Results showed that exposure to IDPN (150 mg/kg/day, v.o.) significantly impaired working memory and that long-term gastrodin (200 mg/kg/day, v.o.) could effectively rescue these IDPN-induced memory impairments as indicated by increased spontaneous alternation in the Y-maze test. Additionally, gastrodin treatment prevented IDPN-induced reductions of dopamine (DA) and its metabolites, as well as elevation of dopamine turnover ratio (DOPAC + HVA)/DA. Gastrodin treatment also prevented alterations in dopamine D2 receptor and dopamine transporter protein levels in the rat hippocampus. Our results suggest that long-term gastrodin treatment may have potential therapeutic values for IDPN-induced cognitive impairments, which was mediated, in part, by normalizing the dopaminergic system.

Gastrodin alleviates memory deficits and reduces neuropathology in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a progressive, neurodegenerative disease, characterized by excessive accumulation of amyloid-beta (Aβ) and activation of microglia cells and astrocytes. In this research, we evaluated whether gastrodin, an active component isolated from the rhizome of Gastrodia elata, has neuroprotective effects in a mouse model of AD, Tg2576 mice. Treatment of gastrodin (60 mg/kg for 15 days) significantly improved memory impairments in the Morris water maze test and probe test. Moreover, immunohistochemical and ELISA results indicated that gastrodin significantly attenuated Aβ deposition and glial activation in brains of these transgenic mice. These findings suggested that gastrodin exerted neuroprotective activity via anti-inflammatory and anti-amyloidogenic effects and that gastrodin may be a potential option for AD therapy.

Gastrodin inhibits the activity of acid-sensing ion channels in rat primary sensory neurons

Acid-sensing ion channels (ASICs), a family of proton-gated cation channels, are believed to mediate pain caused by extracellular acidification. Gastrodin is a main bioactive constituent of the traditional herbal Gastrodia elata Blume, which has been widely used in Oriental countries for centuries. As an analgesic, gastrodin has been used clinically to treat pain such as migraine and headache. However, the mechanisms underlying analgesic action of gastrodin are still poorly understood. Here, we have found that gastrodin inhibited the activity of native ASICs in rat dorsal root ganglion (DRG) neurons. Gastrodin dose-dependently inhibited proton-gated currents mediated by ASICs. Gastrodin shifted the proton concentration-response curve downwards, with a decrease of 36.92 ± 6.23% in the maximum current response but with no significant change in the pH0.5 value. Moreover, gastrodin altered acid-evoked membrane excitability of rat DRG neurons and caused a significant decrease in the amplitude of the depolarization and the number of action potentials induced by acid stimuli. Finally, peripheral applied gastrodin relieved pain evoked by intraplantar injection of acetic acid in rats. Our results indicate that gastrodin can inhibit the activity of ASICs in the primary sensory neurons, which provided a novel mechanism underlying analgesic action of gastrodin.

Neuroprotective effects of dietary supplement Kang-fu-ling against high-power microwave through antioxidant action

KFL displays a protective effect against HPM-induced cognitive impairment and histopathological changes by ameliorating oxidative stress via the Nrf2-ARE signaling pathway.

Gastrodin ameliorates depressive-like behaviors and up-regulates the expression of BDNF in the hippocampus and hippocampal-derived astrocyte of rats

Gastrodin (GAS), a main constituent of a Chinese herbal medicine Tian ma, has been shown to be effective in treating various mood disorders. The purpose of the present study was to assess the effects of GAS on alleviating depressive-like behaviors in a rat model of chronic unpredictable stress (CUS) and regulating the expression of BDNF in the hippocampus and hippocampal-derived astrocyte from Sprague-Dawley (SD) rats. Following CUS, rats were intraperitoneally administered gastrodin (50, 100, or 200 mg/kg daily) or vehicle for 2 weeks. Rats were then experienced sucrose preference test and forced swim test. The expressions of GFAP and BDNF in the hippocampus were evaluated. In addition, hippocampal astrocytes were isolated from neonatal SD rats and exposed to different concentrations of GAS (sham, 5, 10, 20, 50 and 100 μg/mL) for 48 and 72 h before the cell viability and the levels of pERK1/2 and BDNF were analyzed. Furthermore, the cell viability was also tested after exposure to serum-free condition that contain different concentrations of GAS for 48 and 72 h. GAS administration (100 and 200 mg/kg daily) reversed depressive-like behaviors in rats exposed to CUS paradigm and restored the expression of GFAP and BDNF in the hippocampus. Moreover, in vitro experiments revealed that GAS did not increase the cell viability of astrocytes but protected it from 72 h's serum-free damage at the dosage 20 μg/mL. Increased levels of ERK1/2 phosphorylation and BDNF protein were also observed after GAS (20 μg/mL) treatment for 72 h. These results indicate that gastrodin possesses antidepressant effect. The changes of the astrocyte activation and the level of BDNF may play a critical role in the pharmacological action of GAS.

Elution-extrusion counter-current chromatography separation of two new benzyl ester glucosides and three other high-polarity compounds from the tubers of Pleione bulbocodioides

INTRODUCTION

The tubers of Pleione bulbocodioides (Franch.) Rolfe, with gastrodin and benzyl ester glucosides as main components, have been used in traditional Chinese medicine for the treatment of various cancers and bacterial infections. Up to now, their official quality control method is still inadequate, and the difficulty of obtaining these high-polarity compounds is one of the major reasons.

OBJECTIVE

To develop a rapid and efficient method for preparative separation of the high-polarity compounds gastrodin and benzyl ester glucosides.

METHODS

An optimised solvent system composed of n-butanol:ethanol:water (20:1:20, v/v/v) was applied for the elution-extrusion counter-current chromatography (EECCC) separation. The upper phase was used as the stationary phase, and the lower phase was used as the mobile phase at a flow rate of 1.5 mL/min, a rotation speed of 850 rpm and a temperature of 35°C.

RESULTS

Five high-polarity glucosides, including two new compounds, (E)-4-β-D-glucopyranosyloxycinnamic acid 9-(4-β-D-glucopyranosyloxybenzyl) ester (4 mg) and (Z)-2-(2-methylpropyl)butenedioic acid bis(4-β-D-glucopyranosyloxybenzyl) ester (9 mg), and three main components, gastrodin (87 mg), dactylorhin A (60 mg) and militarine (15 mg), with HPLC purities of 95.4%, 96.4%, 91.1%, 97.2% and 95.5% respectively, were yielded from 400 mg of the prepared sample.

CONCLUSION

Elution-extrusion counter-current chromatography could be used as a useful tool for the separation of high-polarity compounds such as gastrodin and benzyl ester glucosides and the enrichment of the minor ones.

Gastrodin ameliorates anxiety-like behaviors and inhibits IL-1beta level and p38 MAPK phosphorylation of hippocampus in the rat model of posttraumatic stress disorder

Gastrodin, a main constituent of a Chinese herbal medicine, has been shown to be effective in treating various mood disorders. The purpose of the present study was to determine whether gastrodin could ameliorate stress-associated behavior in a rat model of enhanced single prolonged stress (ESPS)-induced posttraumatic stress disorder (PTSD). Following ESPS, rats were administered orally with gastrodin (50, 100, or 200 mg/kg daily) or vehicle for 2 weeks. Animals were then tested in the open field and elevated plus-maze, and the levels of IL-6 and IL-1beta, the expression of iNOS, p38 and phospho-p38 (p-p38) in hippocampus were also tested. ESPS exposure resulted in pronounced anxiety-like behavior, elevated IL-6 and IL-1beta levels, and the higher expression of iNOS and p-p38 in hippocampus. However, repeated treatment with gastrodin, particularly at higher doses, reversed the aforementioned changes, including anxiety-like behavior, levels of IL-6 and IL-1beta, and the expression of iNOS and the p38 MAPK phosphorylation. These results indicate that gastrodin possesses anxiolytic effect and may be an effective herbal preparation for the treatment of PTSD.