Dihydromyricetin exerts a rapid antidepressant-like effect in association with enhancement of BDNF expression and inhibition of neuroinflammation

Neuroprotective Effects of Metformin and Berberine in Lipopolysaccharide-Induced Sickness-Like Behaviour in Mice

Sickness behaviour, a set of behavioural changes associated with neuroinflammation, is expressed as decreased mobility and depressed behaviour. Activation of AMP-activated protein kinase (AMPK) is reported to regulate inflammation in conditions such as Alzheimer and traumatic brain injury. Metformin, an antidiabetic agent acting via AMPK activation, possesses anti-inflammatory properties. Similarly, the reported anti-inflammatory activities of berberine could be partially attributed to its ability to activate AMPK. In this study, we investigated the effects of metformin and berberine against lipopolysaccharide (LPS)-induced sickness-like behaviour, associated with neuroinflammation, impaired cognition, and oxidative stress. Swiss albino mice were divided into four groups, normal control, LPS control, metformin treatment, and berberine treatment. The control groups received saline for 7 days. Groups 3 and 4 received metformin (200 mg/kg) and berberine (100 mg/kg), respectively, orally once daily for 7 days. On day 7, 1 h after the treatments, animals received LPS (1.5 mg/kg i.p.) to induce sickness-like behaviour. Open field test (OFT) and forced swim test (FST), were performed within 2 h of LPS administration. Then, proinflammatory cytokines (IL-1β and TNF-α), acetylcholinesterase activity (AChE), and oxidative stress markers were estimated in the brain homogenate. In the LPS control group, immobility state, proinflammatory cytokines, AChE, and lipid peroxidation were significantly increased, whereas the glutathione levels were decreased. Pretreatment with metformin significantly improved immobility in the FST, with reduced IL-1β, oxidative stress markers, and AChE activity. However, no significant changes were observed in OFT. Berberine pretreatment exhibited only an apparent, statistically insignificant, improvement in sickness-like behaviour assessed using FST and OFT, cytokine levels, oxidative markers, and AChE. Several factors affect treatment efficacy, such as treatment duration and administered dose. Considering these, berberine warrants elaborate preclinical evaluation for neuroinflammation. Nevertheless, based on the effects observed, AMPK activators could regulate neuroinflammation, cognition, and oxidative stress linked with sickness-like behaviour.

GSK3-Driven Modulation of Inflammation and Tissue Integrity in the Animal Model

Nowadays, GSK3 is accepted as an enzyme strongly involved in the regulation of inflammation by balancing the pro- and anti-inflammatory responses of cells and organisms, thus influencing the initiation, progression, and resolution of inflammatory processes at multiple levels. Disturbances within its broad functional scope, either intrinsically or extrinsically induced, harbor the risk of profound disruptions to the regular course of the immune response, including the formation of severe inflammation-related diseases. Therefore, this review aims at summarizing and contextualizing the current knowledge derived from animal models to further shape our understanding of GSK3α and β and their roles in the inflammatory process and the occurrence of tissue/organ damage. Following a short recapitulation of structure, function, and regulation of GSK3, we will focus on the lessons learned from GSK3α/β knock-out and knock-in/overexpression models, both conventional and conditional, as well as a variety of (predominantly rodent) disease models reflecting defined pathologic conditions with a significant proportion of inflammation and inflammation-related tissue injury. In summary, the literature suggests that GSK3 acts as a crucial switch driving pro-inflammatory and destructive processes and thus contributes significantly to the pathogenesis of inflammation-associated diseases.

Involvement of PI3K/AKT Pathway in the Rapid Antidepressant Effects of Crocetin in Mice with Depression-Like Phenotypes

The current first-line antidepressants have the drawback of slow onset, which greatly affects the treatment of depression. Crocetin, one of the main active ingredients in saffron (Crocus sativus L.), has been demonstrated to have antidepressant activities, but whether it has a rapid antidepressant effect remains unclear. This study aimed to investigate the onset, duration, and mechanisms of the rapid antidepressant activity of crocetin (20, 40 and 80 mg/kg, intraperitoneal injection) in male mice subjected to chronic restraint stress (CRS). The results of behavioral tests showed that crocetin exerted rapid antidepressant-like effect in mice with depression-like phenotypes, including rapid normalization of depressive-like behaviors within 3 h, and the effects could be maintained for 2 days. Hematoxylin-eosin (HE) and Nissl staining showed that crocetin ameliorated hippocampal neuroinflammation and nerve injuries in mice with depression-like phenotypes. The levels of inflammatory factors, corticosterone and pro brain-derived neurotrophic factor in crocetin-administrated mice serum were significantly reduced compared with those in the CRS group, as well as the levels of inflammatory factors in hippocampus. What's more, Western blot analyses showed that, compared to CRS-induced mice, the relative levels of mitogen-activated kinase phosphatase 1 and toll-like receptor 4 were significantly reduced after the administration of crocetin, and the relative expressions of extracellular signal-regulated kinase 1/2 (ERK1/2), cAMP-response element binding protein, phosphorylated phosphoinositide 3 kinase (p-PI3K)/PI3K, phosphorylated protein kinase B (p-AKT)/AKT, phosphorylated glycogen synthase kinase 3β (p-GSK3β)/GSK3β, phosphorylated mammalian target of rapamycin (p-mTOR)/mTOR were markedly upregulated. In conclusion, crocetin exerted rapid antidepressant effects via suppressing the expression of inflammatory cytokines and the apoptosis of neuronal cells through PI3K/AKT signaling pathways. The rapid antidepressant effect of crocetin (40 mg/kg) could be maintained for at least 2 days after single treatment.

Polyphenols as novel interventions for depression: exploring the efficacy, mechanisms of action, and implications for future research

Numerous animal and human studies have assessed the relationship between polyphenols and outcomes related to depression. However, no comprehensive synthesis of the main findings has been conducted. The aim of this manuscript was to systematically review the available evidence from animal and human studies on the association and the effects of dietary polyphenols on depression and provide recommendations for future research. We based our review on 163 preclinical animal, 16 observational and 44 intervention articles assessing the relationship between polyphenols and outcomes related to depression. Most animal studies demonstrated that exposure to polyphenols alleviated behaviours reported to be associated with depression. However, human studies are less clear, with some studies reporting and inverse relationship between the intake of some polyphenols, and polyphenol rich foods and depression risk and symptoms, while others reporting no association or effect. Hence, while there has been extensive research conducted in animals and there is some supporting evidence in humans, further human studies are required, particularly in younger and clinical populations.

Exploring the multifocal role of phytoconstituents as antidepressants

Depression is the most prevalent and devastating neuropsychiatric disorder. There are several conventional antidepressants used for the treatment of depression. But due to their undesired adverse effects, patient compliance is very poor. Thus, developing novel medications for the treatment of depression is a critical strategic priority for meeting therapeutic demands. Current research is looking for alternatives to traditional antidepressants to reduce undesired side effects and increase efficacy. Phytoconstituents provide a wide research range in antidepressant treatments. In the present article, we have conducted a comprehensive assessment of neurological evidence, which supports the usefulness of phytoconstituents in the treatment of the depressive disorder. Secondary plant metabolites including alkaloids, polyphenols, glycosides, saponins, and terpenoids were found to exhibit antidepressant action. Most of the phytoconstituents were found to mediate their antidepressant effect through the upregulation of brain-derived neurotrophic factor (BDNF), serotonin, noradrenaline, and dopamine. Some were also found to exert antidepressant effects by inhibiting the monoamine oxidase (MAO) activity and hypothalamic-pituitary-adrenal (HPA) axis overactivity.

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

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

Dihydromyricetin Attenuates Depressive-like Behaviors in Mice by Inhibiting the AGE-RAGE Signaling Pathway

Depression is a complex mental disorder, affecting approximately 280 million individuals globally. The pathobiology of depression is not fully understood, and the development of new treatments is urgently needed. Dihydromyricetin (DHM) is a natural flavanone, mainly distributed in Ampelopsis grossedentata. DHM has demonstrated a protective role against cardiovascular disease, diabetes, liver disease, cancer, kidney injury and neurodegenerative disorders. In the present study, we examined the protective effect of DHM against depression in a chronic depression mouse model induced by corticosterone (CORT). Animals exposed to CORT displayed depressive-like behaviors; DHM treatment reversed these behaviors. Network pharmacology analyses showed that DHM's function against depression involved a wide range of targets and signaling pathways, among which the inflammation-linked targets and signaling pathways were critical. Western blotting showed that CORT-treated animals had significantly increased levels of the advanced glycation end product (AGE) and receptor of AGE (RAGE) in the hippocampus, implicating activation of the AGE-RAGE signaling pathway. Furthermore, enzyme-linked immunosorbent assay (ELISA) detected a marked increase in the production of proinflammatory cytokines, interleukin-1 beta (IL-1β), IL-6 and tumor necrosis factor-alpha (TNFα) in the hippocampus of CORT-treated mice. DHM administration significantly counteracted these CORT-induced changes. These findings suggest that protection against depression by DHM is mediated by suppression of neuroinflammation, predominantly via the AGE-RAGE signaling pathway.

Mechanistic insights into the role of plant polyphenols and their nano-formulations in the management of depression

Depression is a condition characterized by low mood and an aversion to activity, that causes behavioral problems, poor quality of life and limits daily life activities. It is considered as the fourth leading cause of disability worldwide. Selective Serotonin Reuptake Inhibitors (SSRIs) Monoamine Oxidase (MAO) inhibitors, Tricyclic Antidepressants (TCAs), and atypical antidepressants are some of the conventional medications used to treat depression. However, only about half of patients with major depressive disorder (MDD) respond effectively to first-line antidepressant therapy. Additionally, there are a number of drawbacks to standard antidepressants, such as anti-cholinergic side effects, drug-drug interactions, and food-drug interactions, which prompts researchers to look at alternative approaches to the treatment of depression. Medicinal plants and their metabolites are extensively tested for their efficacy against depression. Electronic databases such as Google scholar, Science Direct, SciFinder and PubMed were used to search relevant literature on the role of polyphenols in depression. Plants-derived Polyphenols represent a major class of compounds extensively distributed in plants. Number of polyphenols have demonstrated antidepressant activity, among which berberine, piperine, curcumin, naringenin, ascorbic acid and ginsenosides are extensively evaluated. The medicinal plants and their derived compounds mediated synthesized green nanoparticles have also exhibited considerable efficacy in the management of depression. The therapeutic effects of these phytochemicals is mediated via differentiation and inhibition of neuronal cell apoptosis, promotion of neuronal cell survival and modulation of key neurotransmitters. The aim of this study is to review compressively the chemical, pharmacological and neurological evidence showing the potential of polyphenols in depression.

Psychopharmacological properties and therapeutic profile of the antidepressant venlafaxine

Major depression (MD) is one of the most common psychiatric disorders worldwide. Currently, the first-line treatment for MD targets the serotonin system but these drugs, notably the selective serotonin reuptake inhibitors, usually need 4 to 6 weeks before the benefit is felt and a significant proportion of patients shows an unsatisfactory response. Numerous treatments have been developed to circumvent these issues as venlafaxine, a mixed serotonin-norepinephrine reuptake inhibitor that binds and blocks both the SERT and NET transporters. Despite this pharmacological profile, it is difficult to have a valuable insight into its ability to produce more robust efficacy than single-acting agents. In this review, we provide an in-depth characterization of the pharmacological properties of venlafaxine from in vitro data to preclinical and clinical efficacy in depressed patients and animal models of depression to propose an indirect comparison with the most common antidepressants. Preclinical studies show that the antidepressant effect of venlafaxine is often associated with an enhancement of serotonergic neurotransmission at low doses. High doses of venlafaxine, which elicit a concomitant increase in 5-HT and NE tone, is associated with changes in different forms of plasticity in discrete brain areas. In particular, the hippocampus appears to play a crucial role in venlafaxine-mediated antidepressant effects notably by regulating processes such as adult hippocampal neurogenesis or the excitatory/inhibitory balance. Overall, depending on the dose used, venlafaxine shows a high efficacy on depressive-like symptoms in relevant animal models but to the same extent as common antidepressants. However, these data are counterbalanced by a lower tolerance. In conclusion, venlafaxine appears to be one of the most effective treatments for treatment of major depression. Still, direct comparative studies are warranted to provide definitive conclusions about its superiority.

Neuroprotective Effect of Stroke Pretreated Mesenchymal Stem Cells Against Cerebral Ischemia/Reperfusion Injury in Rats

BACKGROUND

Mesenchymal stem cells (MSCs) have been shown to enhance neurological recovery after stroke. A rat middle cerebral artery occlusion model was designed to assess neuroprotective effects of stroke pretreated MSCs on cerebral ischemia/reperfusion injury.

METHODS

MSCs were isolated and cultured in medium with 10% fetal bovine serum, normal control serum, or stroke serum (SS). MSCs were then injected into rats (n = 6 in each group) 1 day after middle cerebral artery occlusion, and feeding continued for 28 days. A battery of behavioral tests, 2,3,5-triphenyltetrazolium chloride staining, hematoxylin-eosin staining, enzyme-linked immunosorbent assay, and terminal deoxynucleotidyl transferase dUTP nick end labeling assay were used to assess neural injury. To detect enhancement of neuronal regeneration and angiogenesis, immunofluorescence and Western blotting were performed to assess expression of trophic factors and growth factors.

RESULTS

After treatment, behavior of rats improved significantly. Infarction area, brain lesion, and apoptosis cells were significantly decreased in the SS-MSCs group compared with the other groups. SS-MSCs also modulated inflammation by attenuating inflammatory cytokines. Furthermore, the number of neurogenesis-positive cells and expression of trophic factors and growth factors were significantly higher in the SS-MSCs group compared with the others. MSCs cultured with fetal bovine serum and normal control serum showed differences in expression of trophic factors and growth factors, but the results were not as good as with SS-MSCs.

CONCLUSIONS

Administration of SS-MCSs after reperfusion led to neuroprotection by inducing the recovery process, including improving pathological changes, behavioral improvement, neurogenesis, suppression of apoptosis and inflammation, and angiogenesis.

Prevention and treatment of natural products from Traditional Chinese Medicine in depression: Potential targets and mechanisms of action

The molecular pathology involved in the development of depression is complex. Many signaling pathways and transcription factors have been demonstrated to display crucial roles in the process of depression occurrence and development. The multi-components and multi-targets of Traditional Chinese Medicine (TCM) are uniquely advantageous in the prevention and treatment of chronic diseases. This review summarizes the pharmacological regulations of natural products from TCM in the prevention and treatment of depression from the aspects of transcription factors (CREB, NF-κB, Nrf2) and molecular signaling pathways (BDNF-TrkB, MAPK, GSK-3β, TLR-4).

Recent update on application of dihydromyricetin in metabolic related diseases

As a new type of natural flavonoids, dihydromyricetin (DMY) has attracted more and more attention. It has a series of pharmacological effects, such as anti-inflammatory, anti-tumor, anti-oxidation, antibacterial and so on, and it is almost no toxicity and with excellent safety. Therefore, even if the bioavailability is poor, it is often added to daily food, beverages and even medicines. In recent years, some researchers have found that DMY can treat some diseases by anti-oxidation, anti-inflammation, promoting cell death and regulate the activity of lipid and glucose metabolism. In addition, the mechanism of DMY on these diseases was also related to the signal pathway of AMPK, PI3K/Akt, PPAR and the participation of microRNAs. This review describes the mechanism of DMY in metabolic related diseases from three aspects: metabolic diseases, liver diseases, and cancers, hoping to provide some new ideas for clinical researches.

Flavonoids and intestinal microbes interact to alleviate depression

Flavonoids have a variety of biological activities that are beneficial to human health. However, owing to low bioavailability, most flavonoids exert beneficial effects in the intestine through metabolism by the flora into a variety of structurally different derivatives. Also, flavonoids can modulate the type and structure of intestinal microorganisms to improve human health. It has been reported that the development of depression is accompanied by changes in the type and number of intestinal microorganisms, and gut microbes can significantly improve depressive symptoms through the gut-brain axis. Therefore, the interaction between flavonoids and intestinal microbes to alleviate depression is discussed. © 2021 Society of Chemical Industry.

Brain-derived neurotrophic factor and inflammation in depression: Pathogenic partners in crime?

Major depressive disorder is a debilitating disorder affecting millions of people each year. Brain-derived neurotrophic factor (BDNF) and inflammation are two prominent biologic risk factors in the pathogenesis of depression that have received considerable attention. Many clinical and animal studies have highlighted associations between low levels of BDNF or high levels of inflammatory markers and the development of behavioral symptoms of depression. However, less is known about potential interaction between BDNF and inflammation, particularly within the central nervous system. Emerging evidence suggests that there is bidirectional regulation between these factors with important implications for the development of depressive symptoms and anti-depressant response. Elevated levels of inflammatory mediators have been shown to reduce expression of BDNF, and BDNF may play an important negative regulatory role on inflammation within the brain. Understanding this interaction more fully within the context of neuropsychiatric disease is important for both developing a fuller understanding of biological pathogenesis of depression and for identifying novel therapeutic opportunities. Here we review these two prominent risk factors for depression with a particular focus on pathogenic implications of their interaction.

Mechanism of Dihydromyricetin on Inflammatory Diseases

Inflammation plays a crucial role in a variety of diseases, including diabetes, arthritis, asthma, Alzheimer’s disease (AD), acute cerebral stroke, cancer, hypertension, and myocardial ischemia. Therefore, we need to solve the problem urgently for the study of inflammation-related diseases. Dihydromyricetin (DHM) is a flavonoid mainly derived from Nekemias grossedentata (Hand.-Mazz.) J.Wen and Z.L.Nie (N.grossedentata). DHM possesses many pharmacological effects, including anti-inflammatory (NLRP-3, NF-κB, cytokines, and neuroinflammation), antioxidant, improving mitochondrial dysfunction, and regulating autophagy and so on. In this review, we consulted the studies in the recent 20 years and summarized the mechanism of DHM in inflammation-related diseases. In addition, we also introduced the source, chemical structure, chemical properties, and toxicity of DHM in this review. We aim to deepen our understanding of DHM on inflammation-related diseases, clarify the relevant molecular mechanisms, and find out the problems and solutions that need to be solved urgently. Providing new ideas for DHM drug research and development, as well as broaden the horizons of clinical treatment of inflammation-related diseases in this review. Moreover, the failure of clinical transformation of DHM poses a great challenge for DHM as an inflammation related disease.

A multifaceted review on dihydromyricetin resources, extraction, bioavailability, biotransformation, bioactivities, and food applications with future perspectives to maximize its value

Natural bioactive compounds present a better alternative to prevent and treat chronic diseases owing to their lower toxicity and abundant resources. (+)-Dihydromyricetin (DMY) is a flavanonol, possessing numerous interesting bioactivities with abundant resources. This review provides a comprehensive overview of the recent advances in DMY natural resources, stereoisomerism, physicochemical properties, extraction, biosynthesis, pharmacokinetics, and biotransformation. Stereoisomerism of DMY should be considered for better indication of its efficacy. Biotechnological approach presents a potential tool for the production of DMY using microbial cell factories. DMY high instability is related to its powerful antioxidant capacity due to pyrogallol moiety in ring B, and whether preparation of other analogues could demonstrate improved properties. DMY demonstrates poor bioavailability based on its low solubility and permeability with several attempts to improve its pharmacokinetics and efficacy. DMY possesses various pharmacological effects, which have been proven by many in vitro and in vivo experiments, while clinical trials are rather scarce, with underlying action mechanisms remaining unclear. Consequently, to maximize the usefulness of DMY in nutraceuticals, improvement in bioavailability, and better understanding of its actions mechanisms and drug interactions ought to be examined in the future along with more clinical evidence.

Emerging Role of Flavonoids as the Treatment of Depression

Depression is one of the most frequently observed psychological disorders, affecting thoughts, feelings, behavior and a sense of well-being in person. As per the WHO, it is projected to be the primitive cause of various other diseases by 2030. Clinically, depression is treated by various types of synthetic medicines that have several limitations such as side-effects, slow-onset action, poor remission and response rates due to complicated pathophysiology involved with depression. Further, clinically, patients cannot be given the treatment unless it affects adversely the job or family. In addition, synthetic drugs are usually single targeted drugs. Unlike synthetic medicaments, there are many plants that have flavonoids and producing action on multiple molecular targets and exhibit anti-depressant action by affecting multiple neuronal transmissions or pathways such as noradrenergic, serotonergic, GABAnergic and dopaminergic; inhibition of monoamine oxidase and tropomyosin receptor kinase B; simultaneous increase in nerve growth and brain-derived neurotrophic factors. Such herbal drugs with flavonoids are likely to be useful in patients with sub-clinical depression. This review is an attempt to analyze pre-clinical studies, structural activity relationship and characteristics of reported isolated flavonoids, which may be considered for clinical trials for the development of therapeutically useful antidepressant.

Effect of dihydromyricetin on hepatic encephalopathy associated with acute hepatic failure in mice

CONTEXT

Hepatic encephalopathy (HE) is a complex neuropsychiatric disease caused by liver failure. Dihydromyricetin (DMY) is a traditional medicine used to treat liver injury.

OBJECTIVE

To investigate the effects of dihydromyricetin (DMY) on hepatic encephalopathy associated with acute hepatic failure mice models established by thioacetamide (TAA) exposure.

MATERIALS AND METHODS

Female BALB/c mouse were randomly divided into control, DMY, TAA, and TAA + DMY groups (n = 8). The first two groups were intraperitoneally injected with saline or 5 mg/kg DMY, respectively. The last two groups were injected with 600 mg/kg TAA to establish HE models, and then the mice in the last group were treated with 5 mg/kg DMY. Neurological and cognition functions were evaluated 24 and 48 h after injection. Mice were sacrificed after which livers and brains were obtained for immunoblot and histopathological analysis, while blood was collected for the analysis of liver enzymes.

RESULTS

In the TAA + DMY group, ALT and AST decreased to 145.31 ± 12.88 U/L and 309.51 ± 25.92 U/L, respectively, whereas ammonia and TBIL decreased to 415.67 ± 41.91 μmol/L and 3.31 ± 0.35 μmol/L, respectively. Moreover, MDA decreased to 10.74 ± 3.97 nmol/g, while SOD and GST increased to 398.69 ± 231.30 U/g and 41.37 ± 21.84 U/g, respectively. The neurological score decreased to 2.87 ± 0.63, and the number of GFAP-positive cells decreased to 41.10 ± 1.66. Furthermore, the protein levels of TNF-α, IL-6, and GABA_A in the cortex decreased.

CONCLUSIONS

We speculate that DMY can serve as a novel treatment for HE.

Anti-Oxidative, Anti-Inflammatory and Anti-Apoptotic Effects of Flavonols: Targeting Nrf2, NF-κB and p53 Pathways in Neurodegeneration

Neurodegenerative diseases are one of the leading causes of disability and death worldwide. Intracellular transduction pathways that end in the activation of specific transcription factors are highly implicated in the onset and progression of pathological changes related to neurodegeneration, of which those related to oxidative stress (OS) and neuroinflammation are particularly important. Here, we provide a brief overview of the key concepts related to OS- and neuroinflammation-mediated neuropathological changes in neurodegeneration, together with the role of transcription factors nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB). This review is focused on the transcription factor p53 that coordinates the cellular response to diverse genotoxic stimuli, determining neuronal death or survival. As current pharmacological options in the treatment of neurodegenerative disease are only symptomatic, many research efforts are aimed at uncovering efficient disease-modifying agents. Natural polyphenolic compounds demonstrate powerful anti-oxidative, anti-inflammatory and anti-apoptotic effects, partially acting as modulators of signaling pathways. Herein, we review the current understanding of the therapeutic potential and limitations of flavonols in neuroprotection, with emphasis on their anti-oxidative, anti-inflammatory and anti-apoptotic effects along the Nrf2, NF-κB and p53 pathways. A better understanding of cellular and molecular mechanisms of their action may pave the way toward new treatments.

Recent advances in research on vine tea, a potential and functional herbal tea with dihydromyricetin and myricetin as major bioactive compounds

Vine tea has been used as an herbal tea by several ethnic minorities for hundreds of years in China. Flavonoids, a kind of indispensable component in a variety of nutraceutical, pharmaceutical and cosmetic applications, are identified to be the major metabolites and bioactive ingredients in vine tea. Interestingly, vine tea exhibits a wide range of significant bioactivities including anti-oxidant, anti-inflammatory, anti-tumor, antidiabetic, neuroprotective and other activities, but no toxicity. These bioactivities, to some extent, enrich the understanding about the role of vine tea in disease prevention and therapy. The health benefits of vine tea, particularly dihydromyricetin and myricetin, are widely investigated. However, there is currently no comprehensive review available on vine tea. Therefore, this report summarizes the most recent studies investigating bioactive constituents, pharmacological effects and possible mechanisms of vine tea, which will provide a better understanding about the health benefits and preclinical assessment of novel application of vine tea.

Evaluation of Anti-inflammatory Nutraceuticals in LPS-induced Mouse Neuroinflammation Model: An Update

It is known that peripheral infections, accompanied by inflammation, represent significant risk factors for the development of neurological disorders by modifying brain development or affecting normal brain aging. The acute effects of systemic inflammation on progressive and persistent brain damage and cognitive impairment are well documented. Anti-inflammatory therapies may have beneficial effects on the brain, and the protective properties of a wide range of synthetic and natural compounds have been extensively explored in recent years. In our previous review, we provided an extensive analysis of one of the most important and widely-used animal models of peripherally induced neuroinflammation and neurodegeneration - lipopolysaccharide (LPS)-treated mice. We addressed the data reproducibility in published research and summarized basic features and data on the therapeutic potential of various natural products, nutraceuticals, with known anti-inflammatory effects, for reducing neuroinflammation in this model. Here, recent data on the suitability of the LPS-induced murine neuroinflammation model for preclinical assessment of a large number of nutraceuticals belonging to different groups of natural products such as flavonoids, terpenes, non-flavonoid polyphenols, glycosides, heterocyclic compounds, organic acids, organosulfur compounds and xanthophylls, are summarized. Also, the proposed mechanisms of action of these molecules are discussed.

Plasma exosomes from depression ameliorate inflammation-induced depressive-like behaviors via sigma-1 receptor delivery

A growing body of studies indicated that exosomes are one of vital players in pathological process of neuropsychiatric diseases, but their role in major depressive disorder (MDD) remains poorly understood. Here we purified plasma exosomes from depression including lipopolysaccharide (LPS)-challenged depression, chronic restraint stress (CRS)-induced depression, MDD subjects, and from control mice or volunteers. The therapeutic effect of these exogenous exosomes was assessed utilizing behavioral tests and biochemical approaches in the LPS-caused depression or microglial BV2 cells. The expression of exosomal sigma-1 receptor (Sig-1R) was evaluated by western blotting. The role of Sig-1R in the biological function of exosomes was determined using Sig-1R knockout mice and HEK 293 cells. Our results revealed that injection of exosomes from depression models or patients rather than normal controls significantly ameliorated depressive-like behaviors, deficiency of BDNF expression and neuro-inflammation in LPS-challenged mice. In addition, co-culture with exosomes from depression models or patients instead of from controls prevented LPS-induced inflammation responses in microglial BV2 cells. Moreover, Sig-1R was demonstrated for the first time to significantly be enriched in exosomes from depression models or patients compared with that from normal controls. However, Sig-1R null exosomes no longer emerged antidepressant-like action in LPS-challenged mice. Thus, we demonstrated that plasma exosomes from depression exerted antidepressant-like effects in a Sig-1R dependent manner in the LPS-induced depression. This work improves our understanding of the exosomes in depression, suggesting a novel exosomes-based approach for MDD treatment.

miR‑146a reduces depressive behavior by inhibiting microglial activation

Depression is one of the major psychiatric diseases affecting the quality of life for individuals worldwide. Numerous reports have investigated depression, although its etiology remains to be elucidated. microRNA (miR)-146a is suggested to regulate innate immune and inflammatory responses. However, it is unclear whether miR-146a is involved in depression. Depression model mice were established using lipopolysaccharide-induced depression and chronic unpredictable mild stress, separately. miR-146a mimic and short interfering RNA were used to treat depressed mice. Depression-like behaviors and levels of pro-inflammatory cytokines were measured, while ionized calcium binding adapter molecule 1 (Iba-1) expression in hippocampus was quantified by immunohistochemistry. Neuroinflammatory factor levels in hippocampus were measured by western blotting. BV-2 cells were used to confirm that miR-146a suppressed microglia activation. Compared with control mice, the two depressed mouse models showed clearly decreased sucrose preference and significantly increased immobility time in the forced swimming test and tail suspension test (P<0.05). miR-146a overexpression significantly increased sucrose preference and reduced immobility time in depressed mice (P<0.05). However, total distance traveled in the locomotor activity test did not differ among groups. Compared with controls, expression levels of Iba-1, inducible nitric oxide, IL-1β, TNF-α, interleukin 1 receptor associated kinase 1 (IRAK1), TNF receptor-associated factor 6 (TRAF6) and phosphorylated NF-κB p65 were significantly increased in depressed mice (P<0.05). miR-146a overexpression effectively inhibited expression of these neuroinflammatory proteins, while miR-146a silencing significantly upregulated their expression (P<0.05). Consistent with these in vivo results, miR-146a mimic treatment inhibited TNF-α, IL-1β, IRAK1 and TRAF6 expression in BV-2 cells. miR-146a improved depressive behaviors in depressed model mice by inhibiting microglial activation and neuroinflammatory factor expression.

Remedial effects of caffeine against depressive-like behaviour in mice by modulation of neuroinflammation and BDNF

Objective: Caffeine (CAF) is one of the most commonly consumed nutritional stimulant in beverages. Interestingly, CAF produces varied effects in a dose-dependent manner, and that makes it one of the most controversial nutritional ingredients. Various studies have linked CAF consumption and reduced risk of depressive disorders. The aim of this study was to investigate the effect of CAF on lipopolysaccharide (LPS)-induced neuroinflammation and depressive-like behaviour.Methods: C57BL/6J male mice were divided into four groups consisting of saline (SAL), LPS, CAF and Imipramine (IMI). Animals were pretreated orally with CAF (10 mg/kg) and IMI (10 mg/kg) for 14 days once daily and all groups except SAL were challenged with LPS (0.83 mg/kg) intraperitoneally on day 14.Results: LPS produced a biphasic behavioural response with a significantly high immobility time and weight loss after 24 h. The brain cytokines (TNF-α, IL-6, IL-1β, and IFN-γ) levels were remarkably high, along with increased lipid peroxidation and reduced Brain Derived Neurotrophic Factor (BDNF). These biochemical and behavioural changes were significantly alleviated by CAF and IMI chronic treatment.Conclusion: The results of this study implicate that mild-moderate consumption of CAF could impart anti-inflammatory properties under neuroinflammatory conditions by modulating the cytokine and neurotrophic mechanisms.

Dihydromyricetin Acts as a Potential Redox Balance Mediator in Cancer Chemoprevention

Dihydromyricetin (DHM) is a flavonoid extracted from the leaves and stems of the edible plant Ampelopsis grossedentata that has been used for Chinese Traditional Medicine. It has attracted considerable attention from consumers due to its beneficial properties including anticancer, antioxidative, and anti-inflammatory activities. Continuous oxidative stress caused by intracellular redox imbalance can lead to chronic inflammation, which is intimately associated with the initiation, promotion, and progression of cancer. DHM is considered a potential redox regulator for chronic disease prevention, and its biological activities are abundantly evaluated by using diverse cell and animal models. However, clinical investigations are still scanty. This review summarizes the current potential chemopreventive effects of DHM, including its properties such as anticancer, antioxidative, and anti-inflammatory activities, and further discusses the underlying molecular mechanisms of DHM in cancer chemoprevention by targeting redox balance and influencing the gut microbiota.

Dihydromyricetin improves mitochondrial outcomes in the liver of alcohol-fed mice via the AMPK/Sirt-1/PGC-1α signaling axis

Alcoholic liver disease (ALD), due to the multifactorial damage associated with alcohol (ethanol) consumption and metabolism, is one of the most prevalent liver diseases in the United States. The liver is the primary site of ethanol metabolism and is subsequently injured due to the production of reactive oxygen species (ROS), acetaldehyde, and metabolic stress. Building evidence suggests that dihydromyricetin (DHM), a bioactive flavonoid isolated from Hovenia dulcis, provides hepatoprotection by enhancing ethanol metabolism in the liver by maintaining hepatocellular bioenergetics, reductions of oxidative stress, and activating lipid oxidation pathways. The present study investigates the utility of DHM on hepatic mitochondrial biogenesis via activation of the AMP-activated protein kinase (AMPK)/Sirtuin (Sirt)-1/PPARG coactivator 1 (PGC)-1α signaling pathway. We utilized a forced drinking ad libitum study that chronically fed 30% ethanol to male C57BL/6J mice over 8 weeks and induced ALD pathology. We found that chronic ethanol feeding resulted in the suppression of AMPK activation and cytoplasmic Sirt-1 and mitochondrial Sirt-3 expression, effects that were reversed with daily DHM administration (5 mg/kg; intraperitoneally [i.p.]). Chronic ethanol feeding also resulted in hepatic hyperacetylation of PGC-1α, which was improved with DHM administration and its mediated increase of Sirt-1 activity. Furthermore, ethanol-fed mice were found to have increased expression of mitochondrial transcription factor A (TFAM), reduced mitochondrial content as assessed by mitochondrial DNA to nuclear DNA ratios, and significantly lower levels of hepatic ATP. In contrast, DHM administration significantly increased TFAM expression, hepatic ATP concentrations, and induced mitochondrial expression of respiratory complex III and V. In total, this work demonstrates a novel mechanism of DHM that improves hepatic bioenergetics, metabolic signaling, and mitochondrial viability, thus adding to the evidence supporting the use of DHM for treatment of ALD and other metabolic disorders.

Agomelatine effects on fat-enriched diet induced neuroinflammation and depression-like behavior in rats

Growing evidence suggests that a high fat diet (HFD) induces oxidative stress on the central nervous system (CNS), which predisposes to mood disorders and neuroinflammation. In this study we postulated that in addition to improving mood, antidepressant therapy would reverse inflammatory changes in the brain of rats exposed to a HFD. To test our hypothesis, we measured the effect of the antidepressant agomelatine (AGO) on anxiety- and depressive-like behaviors, as well as on CNS markers of inflammation in rats rendered obese. Agomelatine is an agonist of the melatonin receptors MT1 and MT2 and an antagonist of the serotonin receptors 5HT2B and 5HT2C. A subset of rats was also treated with lipopolysaccharides (LPS) to determine how additional neuroinflammation alters behavior and affects the response to the antidepressant. Specifically, rats were subjected to a 14-week HFD, during which time behavior was evaluated twice, first at the 10th week prior to LPS and/or agomelatine, and then at the 14th week after a bi-weekly exposure to LPS (250 μg/kg) and daily treatment with agomelatine (40 mg/kg). Immediately after the second behavioral testing we measured the proinflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and interleukin 1 beta (IL-1β), markers of oxidative stress thiobarbituric acid reactive substances (TABRS), catalase (CAT) and glutathione peroxidase (GPx), the growth factor BDNF, as well as the apoptosis marker caspase-3. Our results show that a HFD induced an anxiety-like behavior in the open field test (OFT) at the 10th week, followed by a depressive-like behavior in the forced swim test (FST) at the 14th week. In the prefrontal and hippocampal cortices of rats exposed to a HFD we noted an overproduction of TNF-α, IL-6, IL-1β, and TABRS, together with an increase in caspase-3 activity. We also observed a decrease in BDNF, as well as reduced CAT and GPx activity in the same brain areas. Treatment with agomelatine reversed the signs of anxiety and depression, and decreased the cytokines (TNF-α, IL-6 and IL-1β), TABRS, as well as caspase-3 activity. Agomelatine also restored BDNF levels and the activity of antioxidant enzymes CAT and GPx. Our findings suggest that the anxiolytic/antidepressant effect of agomelatine in obese rats could result from a reversal of the inflammatory and oxidative stress brought about by their diet.

Myricetin bioactive effects: moving from preclinical evidence to potential clinical applications

Several flavonoids have been recognized as nutraceuticals, and myricetin is a good example. Myricetin is commonly found in plants and their antimicrobial and antioxidant activities is well demonstrated. One of its beneficial biological effects is the neuroprotective activity, showing preclinical activities on Alzheimer, Parkinson, and Huntington diseases, and even in amyotrophic lateral sclerosis. Also, myricetin has revealed other biological activities, among them as antidiabetic, anticancer, immunomodulatory, cardiovascular, analgesic and antihypertensive. However, few clinical trials have been performed using myricetin as nutraceutical. Thus, this review provides new insights on myricetin preclinical pharmacological activities, and role in selected clinical trials.

The Effect of Dihydromyricetin, a Natural Flavonoid, on Morphine-induced Conditioned Place Preference and Physical Dependence in Mice

Objective Dihydromyricetin (DHM), a natural flavonoid, is used to reduce alcohol hangover. It has a modulatory role on GABAA receptors with significant effects on seizure and anxiety in animal models. We aimed to evaluate the effect of DHM on morphine conditioned place preference (CPP) and withdrawal sings following morphine dependence using animal models.

Methods The effect of DHM (1, 2 and 5 mg/kg, intraperitoneal; ip) on the acquisition and expression of morphine-induced CPP was evaluated in male mice. Administration of morphine for three consecutive days induced physical dependence. The withdrawal signs such as jumping and defecation were precipitated by administration of naloxone (8 mg/kg, ip). The effect of DHM on the development of physical dependence was assessed by injection of DHM before morphine administrations.

Results DHM, at the dose of 5 mg/kg, reduced expression of morphine CPP with an increase in the locomotor activity. DHM, at the doses of 2 and 5 mg/kg, also reduced development of morphine CPP. DHM alleviated development of morphine-induced physical dependence at the dose of 1, 2, and 5 mg/kg by decreasing jumping and defecation.

Conclusion These results indicated that DHM decreased acquisition and expression of morphine CPP and inhibited development of morphine-induced physical dependence.

Rapid anti-depressant-like effects of ketamine and other candidates: Molecular and cellular mechanisms

Major depressive disorder takes at least 3 weeks for clinical anti‐depressants, such as serotonin selective reuptake inhibitors, to take effect, and only one‐third of patients remit. Ketamine, a kind of anaesthetic, can alleviate symptoms of major depressive disorder patients in a short time and is reported to be effective to treatment‐resistant depression patients. The rapid and strong anti‐depressant‐like effects of ketamine cause wide concern. In addition to ketamine, caloric restriction and sleep deprivation also elicit similar rapid anti‐depressant‐like effects. However, mechanisms about the rapid anti‐depressant‐like effects remain unclear. Elucidating the mechanisms of rapid anti‐depressant effects is the key to finding new therapeutic targets and developing therapeutic patterns. Therefore, in this review we summarize potential molecular and cellular mechanisms of rapid anti‐depressant‐like effects based on the pre‐clinical and clinical evidence, trying to provide new insight into future therapy.

Dietary Flavonoids Interaction with CREB-BDNF Pathway: An Unconventional Approach for Comprehensive Management of Epilepsy

cAMP response element binding protein (CREB) is a key transcriptional regulator that regulates the transcription of genes related with neuronal differentiation, synaptic plasticity, learning and memory. Brain derived neurotrophic factor (BDNF), is a CREB dependent gene which plays a pivotal role in the pathogenesis of epilepsy and central comorbid conditions associated with epilepsy. However, the beneficial or detrimental consequences of CREB-BDNF activation on the induction and/or progression of seizures depend specifically on the region of brain involved and the time of activation. The bioactive molecules that alter the activity of CREB in a way to have specialized effects in different brain regions and neural circuits involved could potentially be utilized for therapeutic purposes. Flavonoids are the polyphenolic compounds which lead to phosphorylation of CREB in the hippocampus, followed by increase in extracellular signal regulated kinase (ERK) and BDNF. Several members of flavonoid family have also showed suppression of epileptic seizures via interaction with CREB/BDNF pathway. Moreover, epilepsy is often accompanied by a number of behavioural and psychological comorbid conditions that further gets aggravated by the use of conventional antiepileptic drug therapy. Multiple studies have also supported the beneficial effects of flavonoids in cognitive and memory impairments by upregulation of CREB-BDNF pathway. The current review is an attempt to collate the available preclinical and clinical studies to establish the therapeutic potential of various dietary flavonoids in comprehensive management of epilepsy with relation to CREB-BDNF pathway.

Bexarotene Improve Depression-Like Behaviour in Mice by Protecting Against Neuro-inflammation and Synaptic Damage

The growing number of evidences suggest that neuroinflammation and synaptic damage are closely related to the onset of depression. Bexarotene (Bex), a retinoid X receptor agonist, is an U.S. Food and Drug Administration-approved drug for the treatment of cutaneous T-cell lymphoma that has recently been reported to have anti-inflammatory and neuroprotective effects in several models of neurological disease including Parkinson's disease, Alzheimer's disease, and so forth. However, the effect of Bex on depression remains unclear. In this study, we investigated effect of Bex on depression-like behaviour in mice induced by lipopolysaccharide (LPS) or corticosterone (CORT). Our results showed that treatment with Bex for 15 days significantly improved LPS-induced depression-like behaviour in social interaction test and CORT-induced depression-like behaviour in forced swimming test and tail suspension test in mice. We found that the Bex treatment depressed the increase in the number of activated microglia and astrocytes in the frontal cortex, and the increase in the levels of inflammatory cytokines TNF-α, IL-1β and IL-6 in LPS-injected mice. Furthermore, Bex treatment also rescued the decrease in the expression of BDNF, and inhibition of CREB/BDNF/ERK pathway, and improved the expression of synaptic related protein in CORT-induced mice. Based on these results, it is possible that Bex reversed depression-like behaviour in mice by reducing neuroinflammation and protecting against synaptic damage induced by LPS or CORT.

Deficiency in Androgen Receptor Aggravates the Depressive-Like Behaviors in Chronic Mild Stress Model of Depression

While androgen receptor (AR) and stress may influence the development of the major depressive disorder (MDD), the detailed relationship, however, remains unclear. Here we found loss of AR accelerated development of depressive-like behaviors in mice under chronic mild stress (CMS). Mechanism dissection indicated that AR might function via altering the expression of miR-204-5p to modulate the brain-derived neurotrophic factor (BDNF) expression to influence the depressive-like behaviors in the mice under the CMS. Adding the antiandrogen flutamide with the stress hormone corticosterone can additively decrease BDNF mRNA in mouse hippocampus mHippoE-14 cells, which can then be reversed via down-regulating the miR-204-5p expression. Importantly, targeting this newly identified AR-mediated miR-204-5p/BDNF/AKT/MAPK signaling with small molecules including 7,8-DHF and fluoxetine, all led to alter the depressive-like behavior in AR knockout mice under CMS exposure. Together, results from these preclinical studies conclude that decreased AR may accelerate the stress-induced MDD via altering miR-204-5p/BDNF/AKT/MAPK signaling, and targeting this newly identified signaling may help in the development of better therapeutic approaches to reduce the development of MDD.

Antidepressant and Antiaging Effects of Açaí (Euterpe oleracea Mart.) in Mice

Depression is a mental disorder that affects 300 million people of all ages worldwide, but fewer than half of those with the condition receive adequate treatment. In addition, the high pharmacological refractoriness (affecting 30%-50% of patients) and toxicity of some classical antidepressants support the pursuit of new therapies. People with this condition show depressed mood, loss of pleasure, high levels of oxidative stress, and accelerated biological aging (decreased telomere length and expression of the telomerase reverse transcriptase (TERT), the enzyme responsible for telomere maintenance). Because of the close relationship between depression and oxidative stress, nutraceuticals with antioxidant properties are excellent candidates for therapy. This study represents the first investigation of the possible antidepressant and antiaging effects of commercial samples of clarified açaí (Euterpe oleracea) juice (EO). This fruit is rich in antioxidants and widely consumed. In this study, mice were treated with saline or EO (10 μL/g, oral) for 4 days and then with saline or lipopolysaccharide (0.5 mg/kg, i.p.) to induce depressive-like behavior. Only four doses of EO were enough to abolish the despair-like and anhedonia behaviors and alterations observed in electromyographic measurements. The antidepression effect of EO was similar to that of imipramine and associated with antioxidant and antiaging effects (preventing lipid peroxidation and increasing TERT mRNA expression, respectively) in three major brain regions involved in depression (hippocampus, striatum, and prefrontal cortex). Additionally, EO significantly protected hippocampal cells, preventing neuronal loss associated with the depressive-like state and nitrite level increases (an indirect marker of nitric oxide production). Moreover, EO alone significantly increased TERT mRNA expression, revealing for the first time a potent antiaging action in the brain that suggests neuroprotection against long-term age-related consequences.

Dihydromyricetin and Salvianolic acid B inhibit alpha-synuclein aggregation and enhance chaperone-mediated autophagy

BACKGROUND

Progressive accumulation of α-synuclein is a key step in the pathological development of Parkinson's disease. Impaired protein degradation and increased levels of α-synuclein may trigger a pathological aggregation in vitro and in vivo. The chaperone-mediated autophagy (CMA) pathway is involved in the intracellular degradation processes of α-synuclein. Dysfunction of the CMA pathway impairs α-synuclein degradation and causes cytotoxicity.

RESULTS

In the present study, we investigated the effects on the CMA pathway and α-synuclein aggregation using bioactive ingredients (Dihydromyricetin (DHM) and Salvianolic acid B (Sal B)) extracted from natural medicinal plants. In both cell-free and cellular models of α-synuclein aggregation, after administration of DHM and Sal B, we observed significant inhibition of α-synuclein accumulation and aggregation. Cells were co-transfected with a C-terminal modified α-synuclein (SynT) and synphilin-1, and then treated with DHM (10 μM) and Sal B (50 μM) 16 hours after transfection; levels of α-synuclein aggregation decreased significantly (68% for DHM and 75% for Sal B). Concomitantly, we detected increased levels of LAMP-1 (a marker of lysosomal homeostasis) and LAMP-2A (a key marker of CMA). Immunofluorescence analyses showed increased colocalization between LAMP-1 and LAMP-2A with α-synuclein inclusions after treatment with DHM and Sal B. We also found increased levels of LAMP-1 and LAMP-2A both in vitro and in vivo, along with decreased levels of α-synuclein. Moreover, DHM and Sal B treatments exhibited anti-inflammatory activities, preventing astroglia- and microglia-mediated neuroinflammation in BAC-α-syn-GFP transgenic mice.

CONCLUSIONS

Our data indicate that DHM and Sal B are effective in modulating α-synuclein accumulation and aggregate formation and augmenting activation of CMA, holding potential for the treatment of Parkinson's disease.

BDNF Alleviates Neuroinflammation in the Hippocampus of Type 1 Diabetic Mice via Blocking the Aberrant HMGB1/RAGE/NF-κB Pathway

Diabetes is a systemic disease that can cause brain damage such as synaptic impairments in the hippocampus, which is partly because of neuroinflammation induced by hyperglycemia. Brain-derived neurotrophic factor (BDNF) is essential in modulating neuroplasticity. Its role in anti-inflammation in diabetes is largely unknown. In the present study, we investigated the effects of BDNF overexpression on reducing neuroinflammation and the underlying mechanism in mice with type 1 diabetes induced by streptozotocin (STZ). Animals were stereotactically microinjected in the hippocampus with recombinant adeno-associated virus (AAV) expressing BDNF or EGFP. After virus infection, four groups of mice, the EGFP+STZ, BDNF+STZ, EGFP Control and BDNF Control groups, received STZ or vehicle treatment as indicated. Three weeks later brain tissues were collected. We found that BDNF overexpression in the hippocampus significantly rescued STZ-induced decreases in mRNA and protein expression of two synaptic plasticity markers, spinophilin and synaptophysin. More interestingly, BDNF inhibited hyperglycemia-induced microglial activation and reduced elevated levels of inflammatory factors (TNF-α, IL-6). BDNF blocked the increase in HMGB1 levels and specifically, in levels of one of the HMGB1 receptors, RAGE. Downstream of HMGB1/RAGE, the increase in the protein level of phosphorylated NF-κB was also reversed by BDNF in STZ-treated mice. These results show that BDNF overexpression reduces neuroinflammation in the hippocampus of type 1 diabetic mice and suggest that the HMGB1/RAGE/NF-κB signaling pathway may contribute to alleviation of neuroinflammation by BDNF in diabetic mice.

Cannabinoid receptor 2 activation mitigates lipopolysaccharide-induced neuroinflammation and sickness behavior in mice

RATIONALE AND OBJECTIVES

Cannabinoid receptor 2 (CB2R) signaling in the brain is associated with the pathophysiology of depression. Sickness behavior, characterized by lessened mobility, social interaction, and depressive behavior, is linked with neuroinflammation, oxidative stress, and immune system. The present study was aimed at evaluating 1-phenylisatin (PI), a CB2R agonist, in sickness behavior.

METHODS

Influence of acute and 7-day activation of CB2R using PI in lipopolysaccharide (LPS)-induced sickness behavior was assessed in mice. An acute injection of LPS (1.5 mg/kg) produced a fully developed sickness behavior in animals within 1 h of administration. The behavioral paradigm was assessed by open field test, forced swim test, and tail suspension test. Further, tumor necrosis factor-α (TNF-α), antioxidant enzymes, and lipid peroxidation were measured in the brain to correlate neuroinflammation and oxidative stress with sickness behavior. Both treatments, PI (20 mg/kg) and imipramine (15 mg/kg), were administered orally (once for acute and once daily for 7-day protocols).

RESULTS

LPS elevated the brain TNF-α level, augmented oxidative stress, and induced the sickness behavior in mice. Acute and 7-day treatment of mice with PI significantly reduced the LPS-induced sickness behavior. In addition, PI inhibited the neuroinflammation evidenced by a reduction in brain TNF-α and oxidative stress.

CONCLUSION

Our data propose that acute and long-term activation of CB2R might prevent neuroinflammation and oxidative stress-associated sickness behavior.

Targeting opioid dysregulation in depression for the development of novel therapeutics

Since the serendipitous discovery of the first class of modern antidepressants in the 1950's, all pharmacotherapies approved by the Food and Drug Administration for major depressive disorder (MDD) have shared a common mechanism of action, increased monoaminergic neurotransmission. Despite the widespread availability of antidepressants, as many as 50% of depressed patients are resistant to these conventional therapies. The significant length of time required to produce meaningful symptom relief with these medications, 4-6 weeks, indicates that other mechanisms are likely involved in the pathophysiology of depression which may yield more viable targets for drug development. For decades, no viable candidate target with a different mechanism of action to that of conventional therapies proved successful in clinical studies. Now several exciting avenues for drug development are under intense investigation. One of these emerging targets is modulation of endogenous opioid tone. This review will evaluate preclinical and clinical evidence pertaining to opioid dysregulation in depression, focusing on the role of the endogenous ligands endorphin, enkephalin, dynorphin, and nociceptin/orphanin FQ (N/OFQ) and their respective receptors, mu (MOR), delta (DOR), kappa (KOR), and the N/OFQ receptor (NOP) in mediating behaviors relevant to depression and anxiety. Finally, putative opioid based antidepressants that are under investigation in clinical trials, ALKS5461, JNJ-67953964 (formerly LY2456302 and CERC-501) and BTRX-246040 (formerly LY-2940094) will be discussed. This review will illustrate the potential therapeutic value of targeting opioid dysregulation in developing novel therapies for MDD.

GSK-3β and BDNF genes may not be associated with venlafaxine treatment response in Chinese of Han ethnicity

PURPOSE

Venlafaxine is one of the commonly prescribed antidepressants for major depressive disorder (MDD). Accumulated evidence revealed the involvement of glutamatergic system in the pathophysiology of MDD and antidepressant treatment.

METHODS

We recruited 193 MDD patients who have been taking venlafaxine for 6 weeks, and investigated whether single nucleotide polymorphisms (SNPs) in GSK-3β and BDNF were associated with treatment response. Nine SNPs were selected randomly depending on association studies. Efficacy of treatment was determined by 17-item Hamilton Rating Scale. Allele and genotype frequencies were compared between responders and nonresponders.

RESULTS

After adjusting the false discovery rate, no significant difference was observed between response and nonresponse groups in allele or genotype distributions after venlafaxine treatment for 6 weeks.

CONCLUSION

Our results indicated that genetic variants in the GSK-3β and BDNF may not be associated with treatment response in MDD patients treated with venlafaxine.

Dihydromyricetin Alleviates Diabetic Neuropathic Pain and Depression Comorbidity Symptoms by Inhibiting P2X7 Receptor

Diabetic neuropathic pain (DNP) and major depressive disorder (MDD) are common complications of diabetes mellitus and mutually affect each other. As a member of the ATP-gated ion channel family, P2X₇ receptor is associated with the transduction of pain signal and the onset of depression. The aim of this study was to investigate the effects of dihydromyricetin (DHM) on rats with comorbid DNP and MDD. After the comorbid model was established, rat behavior changes were monitored by measuring the mechanical withdrawal threshold, thermal withdrawal latency, sugar water preference, immobility time in the forced-swim test, and open-field test parameters. The expressions of P2X₇ receptor in the dorsal root ganglia (DRGs), spinal cord, and hippocampus were assessed by quantitative real-time PCR, Western blotting, and double immunofluorescence. We found that hyperalgesia, allodynia, and depressive behaviors of rats with comorbid DNP and MDD were relieved by treatment with DHM or application of a short-hairpin RNA for P2X₇ receptor. The expression levels of P2X₇, phosphorylated extracellular signal-regulated kinase 1/2, tumor necrosis factor α, and interleukin 1ß were increased in the DRGs, spinal cord, and hippocampus of rats in the model group but restored after DHM or P2X₇ short-hairpin RNA treatment. In conclusion, P2X₇ receptor in the DRGs, spinal cord, and hippocampus participates in the transduction of DNP and MDD signals. DHM seems to relieve comorbid DNP and MDD by reducing the expression of P2X₇ receptor in the DRGs, spinal cord, and hippocampus and may be an effective new drug for the treatment of patients with both DNP and MDD.

Dihydromyricetin Attenuates Metabolic Syndrome And Improves Insulin Sensitivity By Upregulating Insulin Receptor Substrate-1 (Y612) Tyrosine Phosphorylation In db/db Mice

PURPOSE

Dihydromyricetin (DHM), the main bioactive flavonoid in vine tea, exerts multiple health beneficial effects. This work aimed to identify whether a naturally derived flavonoid product, DHM, can significantly attenuate metabolic syndrome and improve insulin sensitivity.

METHODS

10-week-old db/db mice were randomly assigned to receive the antidiabetic agent metformin (Met, 50 mg/kg BW), DHM (1.0 g and 0.5 g/kg BW) or placebo and were simultaneously fed a high-fat diet for 8 weeks. The general status of the animals was observed and recorded daily, body weight and blood glucose levels were measured weekly, during the experimental period. On day 55, the oral glucose tolerance test (OGTT) was performed. After OGTT, all animals were anesthetized and sacrificed by cervical decapitation. Blood samples were collected in tubes to detect plasma insulin and the biochemical parameters of lipid metabolism. Pancreas histological changes and islet fibrosis were demonstrated by H&E staining and Masson staining, respectively. Moreover, the expression of insulin receptor substrate-1 and phosphorylated insulin receptor substrate-1 in the insulin signaling pathway was detected by Western blot assay.

RESULTS

The oral administration of DHM (1.0 g and 0.5 g/kg BW) reduced the fasting blood glucose, serum insulin, and glycated hemoglobin levels and the insulin resistance (HOMA-IR) index. Furthermore, DHM intervention decreased body weight and the serum lipid profile. In addition, DHM treatment also markedly decreased the relative abdominal fat weight. Western blot analysis indicated that DHM upregulated the IRS-1 (Y612) tyrosine phosphorylation, improving insulin resistance. Treatment with dihydromyricetin attenuated the progression of insulin resistance and pancreatic fibrosis in fatty db/db mice.

CONCLUSION

In summary, we determined the antimetabolic syndrome effect of DHM in db/db obese mice. DHM upregulates the IRS-1 (Y612) tyrosine phosphorylation, improving insulin resistance. Therefore, DHM is a promising therapeutic candidate for the control of metabolic syndrome.

Semaphoring 4D is required for the induction of antioxidant stress and anti-inflammatory effects of dihydromyricetin in colon cancer

Semaphorin 4D (Sema4D) has been involved in cancer progression, the expression of which is associated with the poor clinical outcomes of some cancer patients. Dihydromyricetin (DMY) has antitumor potentials for different types of human cancer cells. However, the pharmacological effects of DMY on colon cancer (CC) or the regulatory effects of Sema4D on this process remain largely unknown. In the present study, we aimed to evaluate the effects of DMY on CC, and to elucidate the role of Sema4D in DMY-induced antitumor effects. DMY inhibited the proliferation and growth of Colo-205 colon cancer cells significantly in vivo and in vitro. DMY inhibited reactive oxygen species (ROS) and malondialdehyde (MDA) levels, but increased glutathione (GSH) level. Moreover, the activities of antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and heme oxygenase 1 (HO-1) were enhanced by DMY treatment in vitro, showing strong anti-oxidative stress effect. In addition, DMY inhibited the secretion of interleukin 1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor (TNF-α) in the supernatant of Colo-205 culture medium. Besides, the expressions of cyclooxygenase (COX-2) and inducible nitric oxide synthase (iNOS) were suppressed by DMY in dose-dependent manners in vivo, showing potent anti-inflammatory effect. Further investigations showed that DMY suppressed the expression and secretion of Sema4D in Colo-205 cells and tissues. Interestingly, overexpression of Sema4D significantly weakened the regulatory effects of DMY on oxidative stress. Furthermore, overexpression of Sema4D significantly attenuated the anti-inflammatory effects of DMY. Collectively, we drew a conclusion that the anti-colon cancer effect of DMY was attributed to its negative modulation on oxidative stress and inflammation via suppression of Sema4D. The findings broaden the width and depth of molecular mechanisms involved in the DMY action, facilitating the development of DMY in anti-colon cancer therapies.

Recent Update on the Pharmacological Effects and Mechanisms of Dihydromyricetin

As the most abundant natural flavonoid in rattan tea, dihydromyricetin (DMY) has shown a wide range of pharmacological effects. In addition to the general characteristics of flavonoids, DMY has the effects of cardioprotection, anti-diabetes, hepatoprotection, neuroprotection, anti-tumor, and dermatoprotection. DMY was also applied for the treatment of bacterial infection, osteoporosis, asthma, kidney injury, nephrotoxicity and so on. These effects to some extent enrich the understanding about the role of DMY in disease prevention and therapy. However, to date, we still have no outlined knowledge about the detailed mechanism of DMY, which might be related to anti-oxidation and anti-inflammation. And the detailed mechanisms may be associated with several different molecules involved in cellular apoptosis, oxidative stress, and inflammation, such as AMP-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK), protein kinase B (Akt), nuclear factor-κB (NF-κB), nuclear factor E2-related factor 2 (Nrf2), ATP-binding cassette transporter A1 (ABCA1), peroxisome proliferator-activated receptor-γ (PPARγ) and so on. Here, we summarized the current pharmacological developments of DMY as well as possible mechanisms, aiming to push the understanding about the protective role of DMY as well as its preclinical assessment of novel application.

Dihydromyricetin Inhibits Lead-Induced Cognitive Impairments and Inflammation by the Adenosine 5'-Monophosphate-Activated Protein Kinase Pathway in Mice

Dihydromyricetin (DHM), a natural flavonoid derived from the medicinal and edible plant Ampelopsis grossedentata, exhibits antioxidant, antiapoptosis, antitumor, and anti-inflammatory bioactivities. This study evaluated the effects of DHM on Pb-induced neurotoxicity and explored the underlying mechanisms. DHM significantly ameliorated behavioral impairments of Pb-induced mice. It decreased the levels of lipid peroxidation and protein carbonyl and increased the activities of superoxide dismutase and catalase in the brains. DHM suppressed Pb-induced apoptosis, as indicated by the decreased levels of Bax and cleaved caspase-3. DHM also decreased inflammatory cytokines in the brains of Pb-treated mice. DHM decreased amyloid-beta (Aβ) level and nuclear factor-κB nuclear translocation. Moreover, DHM induced the adenosine 5'-monophosphate-activated protein kinase (AMPK) phosphorylation and inhibited the activation of p38, Toll-like receptor 4, myeloid differentiation factor 88, and glycogen synthase kinase-3. Collectively, this is the first report indicating that DHM could improve Pb-induced cognitive functional impairment by preventing oxidative stress, apoptosis, and inflammation and that the protective effect was mediated partly through the AMPK pathway.

Advances in the Preclinical Study of Some Flavonoids as Potential Antidepressant Agents

Flavonoids are phenolic compounds found commonly in plants that protect them against the negative effects of environmental insults. These secondary metabolites have been widely studied in preclinical research because of their biological effects, particularly as antioxidant agents. Diverse flavonoids have been studied to explore their potential therapeutic effects in the treatment of disorders of the central nervous system, including anxiety and depression. The present review discusses advances in the study of some flavonoids as potential antidepressant agents. We describe their behavioral, physiological, and neurochemical effects and the apparent mechanism of action of their preclinical antidepressant-like effects. Natural flavonoids produce antidepressant-like effects in validated behavioral models of depression. The mechanism of action of these effects includes the activation of serotonergic, dopaminergic, noradrenergic, and γ-aminobutyric acid-ergic neurotransmitter systems and an increase in the production of neural factors, including brain-derived neurotrophic factor and nerve growth factor. Additionally, alterations in the function of tropomyosin receptor kinase B and activity of the enzyme monoamine oxidase A have been reported. In conclusion, preclinical research supports the potential antidepressant effects of some natural flavonoids, which opens new possibilities of evaluating these substances to develop complementary therapeutic alternatives that could ameliorate symptoms of depressive disorders in humans.