Antidepressant-like Effects of Degraded Porphyran Isolated from Porphyra haitanensis

Regulation of the microglial polarization for alleviating neuroinflammation in the pathogenesis and therapeutics of major depressive disorder

Major depressive disorder (MDD), as a multimodal neuropsychiatric and neurodegenerative illness with high prevalence and disability rates, has become a burden to world health and the economy that affects millions of individuals worldwide. Neuroinflammation, an atypical immune response occurring in the brain, is currently gaining more attention due to its association with MDD. Microglia, as immune sentinels, have a vital function in regulating neuroinflammatory reactions in the immune system of the central nervous system. From the perspective of steady-state branching states, they can transition phenotypes between two extremes, namely, M1 and M2 phenotypes are pro-inflammatory and anti-inflammatory, respectively. It has an intermediate transition state characterized by different transcriptional features and the release of inflammatory mediators. The timing regulation of inflammatory cytokine release is crucial for damage control and guiding microglia back to a steady state. The dysregulation can lead to exorbitant tissue injury and neuronal mortality, and targeting the cellular signaling pathway that serves as the regulatory basis for microglia is considered an essential pathway for treating MDD. However, the specific intervention targets and mechanisms of microglial activation pathways in neuroinflammation are still unclear. Therefore, the present review summarized and discussed various signaling pathways and effective intervention targets that trigger the activation of microglia from its branching state and emphasizes the mechanism of microglia-mediated neuroinflammation associated with MDD.

Recent advance of physicochemical, structural properties, potential health benefits and application of bioactive macromolecules from Porphyra haitanensis: A review

Porphyra haitanensis (P. haitanensis) belongs to the class Rhodophyta and the family Bangiaceae, which is a unique artificially cultivated seaweed in China, especially in the coastal areas of Fujian and Zhejiang province. P. haitanensis is rich in amino acids, mineral elements, proteins, polysaccharides, and trace elements, with proteins and polysaccharides being the main components. P. haitanensis proteins and polysaccharides have variety of biological activities, including antioxidant, anticancer, immunomodulatory, anti-allergic and anti-aging activities, among others. This review introduced and summarized the preparation, isolation and purification, phytochemistry and structural properties, and biological activities of P. haitanensis proteins and polysaccharide, as well as their biomedical and food applications. Furthermore, a thorough analysis of the current trends and perspectives on P. haitanensis bioactive macromolecules were highlighted and prospected. Hopefully, this review can provide a useful reference value for the development and application of P. haitanensis bioactive macromolecules in the field of biomedical and food in the future.

Directed preparation of algal oligosaccharides with specific structures by algal polysaccharide degrading enzymes

Seaweed polysaccharides have a wide range of sources and rich content, with various biological activities such as anti-inflammatory, anti-tumor, anticoagulant, and blood pressure lowering. They can be applied in fields such as food, agriculture, and medicine. However, the poor solubility of macromolecular seaweed polysaccharides limits their further application. Reports have shown that some biological activities of seaweed oligosaccharides are more extensive and superior to that of seaweed polysaccharides. Therefore, reducing the degree of polymerization of polysaccharides will be the key to the high value utilization of seaweed polysaccharide resources. There are three main methods for degrading algal polysaccharides into algal oligosaccharides, physical, chemical and enzymatic degradation. Among them, enzymatic degradation has been a hot research topic in recent years. Various types of algal polysaccharide hydrolases and related glycosidases are powerful tools for the preparation of algal oligosaccharides, including α-agarases, β-agaroses, α-neoagarose hydrolases and β-galactosidases that are related to agar, κ-carrageenases, ι-carrageenases and λ-carrageenases that are related to carrageenan, β-porphyranases that are related to porphyran, funoran hydrolases that are related to funoran, alginate lyases that are related to alginate and ulvan lyases related to ulvan. This paper describes the bioactivities of agar oligosaccharide, carrageenan oligosaccharide, porphyran oligosaccharide, funoran oligosaccharide, alginate oligosaccharide and ulvan oligosaccharide and provides a detailed review of the progress of research on the enzymatic preparation of these six oligosaccharides. At the same time, the problems and challenges faced are presented to guide and improve the preparation and application of algal oligosaccharides in the future.

Polysaccharides from Porphyra haitanensis: A Review of Their Extraction, Modification, Structures, and Bioactivities

Porphyra haitanensis (P. haitanensis), an important food source for coastal residents in China, has a long history of medicinal and edible value. P. haitanensis polysaccharides are some of the main active ingredients in P. haitanensis. It is worth noting that P. haitanensis polysaccharides have a surprising and satisfactory biological activity, which explains the various benefits of P. haitanensis to human health, such as anti-oxidation, immune regulation, anti-allergy, and anticancer properties. Hence, a systematic review aimed at comprehensively summarizing the recent research advances in P. haitanensis polysaccharides is necessary for promoting their better understanding. In this review, we systematically and comprehensively summarize the research progress on the extraction, purification, structural characterization, modification, and biological activity of P. haitanensis polysaccharides and address the shortcomings of the published research and suggest area of focus for future research, providing a new reference for the exploitation of polysaccharides from P. haitanensis in the fields of medicine and functional foods.

Chronic Stress-Induced Neuroinflammation: Relevance of Rodent Models to Human Disease

The brain is the central organ of adaptation to stress because it perceives and determines threats that induce behavioral, physiological, and molecular responses. In humans, chronic stress manifests as an enduring consistent feeling of pressure and being overwhelmed for an extended duration. This can result in a persistent proinflammatory response in the peripheral and central nervous system (CNS), resulting in cellular, physiological, and behavioral effects. Compounding stressors may increase the risk of chronic-stress-induced inflammation, which can yield serious health consequences, including mental health disorders. This review summarizes the current knowledge surrounding the neuroinflammatory response in rodent models of chronic stress-a relationship that is continually being defined. Many studies investigating the effects of chronic stress on neuroinflammation in rodent models have identified significant changes in inflammatory modulators, including nuclear factor-κB (NF-κB) and toll-like receptors (TLRs), and cytokines, including tumor necrosis factor-alpha (TNF-α), interleukin (IL)-1β, and IL-6. This suggests that these are key inflammatory factors in the chronic stress response, which may contribute to the establishment of anxiety and depression-like symptoms. The behavioral and neurological effects of modulating inflammatory factors through gene knockdown (KD) and knockout (KO), and conventional and alternative medicine approaches, are discussed.

A review of the pharmacological action and mechanism of natural plant polysaccharides in depression

Depression is a prevalent mental disorder. However, clinical treatment options primarily based on chemical drugs have demonstrated varying degrees of adverse reactions and drug resistance, including somnolence, nausea, and cognitive impairment. Therefore, the development of novel antidepressant medications that effectively reduce suffering and side effects has become a prominent area of research. Polysaccharides are bioactive compounds extracted from natural plants that possess diverse pharmacological activities and medicinal values. It has been discovered that polysaccharides can effectively mitigate depression symptoms. This paper provides an overview of the pharmacological action and mechanisms, intervention approaches, and experimental models regarding the antidepressant effects of polysaccharides derived from various natural sources. Additionally, we summarize the roles and potential mechanisms through which these polysaccharides prevent depression by regulating neurotransmitters, HPA axis, neurotrophic factors, neuroinflammation, oxidative stress, tryptophan metabolism, and gut microbiota. Natural plant polysaccharides hold promise as adjunctive antidepressants for prevention, reduction, and treatment of depression by exerting their therapeutic effects through multiple pathways and targets. Therefore, this review aims to provide scientific evidence for developing polysaccharide resources as effective antidepressant drugs.

Adult hippocampal neurogenesis: pharmacological mechanisms of antidepressant active ingredients in traditional Chinese medicine

Depression is characterized by prominent indicators and manifestations, such as anhedonia, which refers to the inability to experience pleasure, and persistent feelings of hopelessness. In clinical practice, the primary treatment approach involves the utilization of selective serotonin reuptake inhibitors (SSRIs) and related pharmacological interventions. Nevertheless, it is crucial to recognize that these agents are associated with significant adverse effects. Traditional Chinese medicine (TCM) adopts a multifaceted approach, targeting diverse components, multiple targets, and various channels of action. TCM has potential antidepressant effects. Anomalies in adult hippocampal neurogenesis (AHN) constitute a pivotal factor in the pathology of depression, with the regulation of AHN emerging as a potential key measure to intervene in the pathogenesis and progression of this condition. This comprehensive review presented an overview of the pharmacological mechanisms underlying the antidepressant effects of active ingredients found in TCM. Through examination of recent studies, we explored how these ingredients modulated AHN. Furthermore, we critically assessed the current limitations of research in this domain and proposed novel strategies for preclinical investigation and clinical applications in the treatment of depression in future.

Role of BDNF-TrkB signaling in the antidepressant-like actions of loganin, the main active compound of Corni Fructus

AIMS

Corni Fructus (CF) and some CF-contained prescriptions are commonly used in clinical treatment of depression. This investigation aims to evaluate the main active compound of CF in antidepressant properties and its key target.

METHODS

Firstly, this study established a behavioral despair model and used high-performance liquid chromatography method to evaluate the antidepressant-like effects of water extract, 20%, 50%, and 80% ethanol extracts of CF, and its main active compound. Then, this study created chronic unpredictable mild stress (CUMS) model to assess loganin's antidepressant-like properties, and its target was evaluated by quantitative real-time polymerase chain reaction, Western blot, Immunofluorescence, enzyme-linked immunosorbent assay, and tyrosine receptor kinase B (TrkB) inhibitor.

RESULTS

Results showed that the different extracts of CF significantly shortened the immobility time in forced swimming and tail suspension tests. Moreover, loganin alleviated CUMS-induced depression-like behavior, promoted neurotrophy and neurogenesis, and inhibited neuroinflammation. Furthermore, K252a blocked the improvement of loganin on depression-like behavior, and eliminated the enhancement of neurotrophy and neurogenesis and the inhibition of neuroinflammation.

CONCLUSION

Overall, these results indicated that loganin could be used as a major active compound of CF for the antidepressant-like properties and exerted antidepressant-like actions by regulating brain derived neurotrophic factor (BDNF)-TrkB signaling, and TrkB could be used as key target for itsantidepressant-like actions.

Roles of microglia in adult hippocampal neurogenesis in depression and their therapeutics

Adult hippocampal neurogenesis generates functional neurons from neural progenitor cells in the hippocampal dentate gyrus (DG) to complement and repair neurons and neural circuits, thus benefiting the treatment of depression. Increasing evidence has shown that aberrant microglial activity can disrupt the appropriate formation and development of functional properties of neurogenesis, which will play a crucial role in the occurrence and development of depression. However, the mechanisms of the crosstalk between microglia and adult hippocampal neurogenesis in depression are not yet fully understood. Therefore, in this review, we first introduce recent discoveries regarding the roles of microglia and adult hippocampal neurogenesis in the etiology of depression. Then, we systematically discuss the possible mechanisms of how microglia regulate adult hippocampal neurogenesis in depression according to recent studies, which involve toll-like receptors, microglial polarization, fractalkine-C-X3-C motif chemokine receptor 1, hypothalamic-pituitary-adrenal axis, cytokines, brain-derived neurotrophic factor, and the microbiota-gut-brain axis, etc. In addition, we summarize the promising drugs that could improve the adult hippocampal neurogenesis by regulating the microglia. These findings will help us understand the complicated pathological mechanisms of depression and shed light on the development of new treatment strategies for this disease.

Areca catechu L. ameliorates chronic unpredictable mild stress-induced depression behavior in rats by the promotion of the BDNF signaling pathway

OBJECTIVES

In this study, we have investigated the anti-depressant effects of the fruit Areca catechu L. (ACL) and elucidated its potential underlying mechanism using a rat model of chronic unpredictable mild stress (CUMS).

METHODS

CUMS was induced in rats to establish a depression animal model for 28 days. According to the baseline sucrose preference, the male rats were divided into 6 different groups. They were treated with paroxetine hydrochloride, ACL, and water once a day until the behavioral tests were performed. The levels of corticosterone (CORT), malondialdehyde (MDA), catalase (CAT), and total superoxide dismutase (T-SOD) in serum were detected using a commercial kit, and the concentrations of 5-hydroxytryptamine (5-HT) and dopamine (DA) monoamine neurotransmitters in the brain tissues were detected by liquid chromatography-tandem mass spectrometry. doublecortin (DCX) expression in the hippocampal dentate gyrus (DG) was determined by immunofluorescence, and the relative abundance of brain-derived neurotrophic factor (BDNF), TrkB, PI3K, p-AKT/AKT, PSD-95, and p-GSK-3β/GSK-3β of brain tissues were assayed by western blot.

RESULTS

ACL markedly increased sucrose preference, decreased the immobility time, and shortened the feeding latency of CUMS-induced rats. CUMS induction resulted in marked changes in the contents of the monoamine neurotransmitters (5-HT and DA) in the hippocampus and cortex of brain tissues and the levels of CORT, MDA, CAT, and T-SOD in serum, whereas ACL administration alleviated these considerable changes. ACL promoted DCX expression in DG and increased the protein levels of BDNF, TrkB, PI3K, p-AKT/AKT, PSD-95, and p-GSK-3β/GSK-3β in the brains of CUMS-induced rats.

CONCLUSIONS

Our results indicated that ACL may improve depression-like behaviors in CUMS-induced rats by decreasing the hyperfunction and oxidative stress of the hypothalamic-pituitary-adrenal axis, stimulating hippocampal neurogenesis, and activating the BDNF signaling pathway.

Patchouli alcohol ameliorates depression-like behaviors through inhibiting NLRP3-mediated neuroinflammation in male stress-exposed mice

BACKGROUND

Microglia-mediated neuroinflammation contributes to major depressive disorder (MDD). Targeting microglia is a promising strategy for treating MDD. Patchouli alcohol (PA), an active component of Pogostemon cablin, has anti-inflammatory and neuroprotective effects.

PURPOSE

In this study, we investigate the microglia-mediated neurogenesis pathway in which PA ameliorates depressive-like behaviors in stress-induced animal model of depression.

METHODS

C57BL/6J male mice were exposed to chronic mild stress (CMS) for 4 weeks, then administered PA intraperitoneally at 10, 20 or 40 mg/kg once per day for 3 weeks. The antidepressant effects of PA were evaluated in the sucrose preference test, forced swimming test, and tail suspension test. Microglial phenotypes and activation of the NLRP3 inflammation were analyzed using RT-PCR, western blotting and immunofluorescence staining. Effects of PA on neurogenesis were analyzed in vitro and in vivo using immunofluorescence staining.

RESULTS

Behavioral assessments showed that PA alleviated depressive-like behaviors in CMS-exposed mice. CMS induced microglial activation and pro-inflammatory profiles, which were blocked by PA treatment. PA attenuated the activation of NLRP3 inflammasome, leading to decreases in the levels of caspase-1, ASC, IL-1β, and IL-18 in the hippocampus of CMS-exposed mice. In primary microglia cultures, PA inhibited LPS-induced NLRP3 inflammasome activation. PA rescued inflammation-inhibited neurogenesis in vivo and in vitro.

CONCLUSIONS

Our results suggest that PA inhibits the NLRP3 inflammasome and ameliorates microglia-mediated neurogenesis impairment, contributing to antidepressant effects. Thus, PA may be a novel treatment for inflammation-driven mental disorders.

Study on Lactiplantibacillus plantarum R6-3 from Sayram Ketteki to prevent chronic unpredictable mild stress-induced depression in mice through the microbiota-gut-brain axis

The prevention, mitigation and treatment of depression has become a global issue that needs to be solved urgently. Sayram Ketteki, a traditional natural fermented yoghurt from the region with the world's fourth highest life expectancy, has been known as the "longevity secret", whose longevity and anti-depression factors are speculated to come from its rich microorganisms. Therefore, for the first time, we systematically studied in depth the microbes of Sayram Ketteki, screened a new edible probiotic strain, Lactiplantibacillus plantarum R6-3, and explored its anti-depression effect in chronic unpredictable mild stress (CUMS)-induced depression in mice. It is encouraging that L. plantarum R6-3 was significantly superior to the classic anti-depressant drug, fluoxetine, in the performance of promoting sucrose preference test (SPT) behavior by 18% (p < 0.001), lowering the serum CORT content by 5.6% (p < 0.05), accelerating the brain-derived neurotrophic factor (BDNF) level by 5.9% (p < 0.01), increasing the serum IL-10 concentration by 2.3% (p < 0.05), up-regulating the expression of BDNF and phosphorylated-ERK by 74% (p < 0.01) and 45% (p < 0.001), respectively, and facilitating the secretion of fecal short-chain fatty acids (SCFAs), including n-butyric, n-valeric, and isovaleric acid by 47% (p < 0.01), 42% (p < 0.05) and 38% (p < 0.05), respectively. Through the microbiota-gut-brain axis, L. plantarum R6-3 promoted the secretion of intestinal SCFAs through regulation of the composition and function of the gut microbiota, and activated the production of the monoamine neurotransmitter, renewed the level of brain neurotrophic factor, and suppressed the hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis by adjusting the hippocampal BDNF/TrkB/ERK/CREB signaling pathway, thereby improving the immune and oxidative stress status, protecting hippocampal tissue from damage, maintaining a healthy weight and preventing CUMS-induced depressive behavior in mice. It has great prospects for the development of natural functional foods, the prevention and treatment of depression and in innovative microecological preparations.

Inhibition of Microglial NLRP3 with MCC950 Attenuates Microglial Morphology and NLRP3/Caspase-1/IL-1β Signaling In Stress-induced Mice

Major depressive disorder is characterized by the deficiencies of monoamine neurotransmitters, neurotrophic factors and persistent neuroinflammation. Microglial activation has been associated with neuroinflammation-related mental diseases, accompanied by NLR family pyrin domain containing 3 (NLRP3) inflammasome. Here, we investigated the effect of NLRP3 inhibition by its small molecular inhibitor MCC950 on inflammatory activity and depressive-like mice induced by chronic unpredictable mild stress (CUMS), followed by the behavioral tests including sucrose preference test and forced swimming test. NLRP3/caspase-1/IL-1β signaling and microglial morphology in the prefrontal cortex were measured. The results showed that CUMS caused a decrease in sucrose preference and an increase in immobility time, which were reversed by NLRP3 inhibitor MCC950. In addition, NLRP3 inhibition decreased the number of microglia and changed the activated state of microglia to a resting state by morphology 3D reconstruction. Moreover, NLRP3 inhibition inactivated NLRP3/caspase-1/IL-1β signaling in the prefrontal cortex. The results from immunofluorescence demonstrated that NLRP3 and IL-1β expression was decreased in microglia in response to MCC950 treatment. Accordingly, proinflammatory cytokines were also decreased by NLRP3 inhibition. In conclusion, this study demonstrates that microglial NLRP3 inhibition prevents stress-induced neuroinflammation in the prefrontal cortex and suggests that microglial NLRP3 could be one of the potential therapeutic targets for depression treatment.

Alternative protein sources of plant, algal, fungal and insect origins for dietary diversification in search of nutrition and health

This review aimed to compare alternative protein sources in terms of nutritional composition and health benefits with the purpose of disseminating up-to-date knowledge and contribute for diversification of the food marked and consumers decision-making. Plant-based is the most well-established category of alternative proteins, but there is still room for diversification. Less conventional species such as chia seeds are prominent sources of ω-3 (∼60% total lipids), while hempseed and quinoa are notable sources of ω-6 (up to 58% and 61%, respectively). Edible insects and microalgae are alternative foods rich in protein (up to 70%), fibers (∼30%), as well as peptides and polysaccharides with antimicrobial, antioxidant, anti-hypertensive, antidiabetic, antidepressant, antitumor, and immunomodulatory activities. Additionally, lipid contents in insect larvae can be as high as 50%, on a dry weight basis, containing fatty acids with anti-inflammatory and antitumor properties. In contrast, edible fungi have low lipid contents (∼2%), but are rich in carbohydrates (up to 79%) and have balanced amino acid profiles. The results suggest that food formulations combining different alternative protein sources can meet dietary requirements. Further studies on flavoring and texturing processes will help to create meat and dairy analogs, thus helping to broaden acceptance and applicability of alternative protein sources.

Active Flavonoids From Lagotis brachystachya Attenuate Monosodium Urate-Induced Gouty Arthritis via Inhibiting TLR4/MyD88/NF-κB Pathway and NLRP3 Expression

Lagotis brachystachya Maxim is a characteristic herb commonly used in Tibetan medicine. Tibetan medicine records it as an important medicine for the clinical treatment of “Yellow Water Disease,” the symptoms of which are similar to that of arthritis. Our previous study showed that the flavonoid fraction extracted from L. brachystachya could attenuate hyperuricemia. However, the effects of the active flavonoids on gouty arthritis remain elusive, and the underlying mechanism is not understood. In the present study, the effects of the active flavonoids were evaluated in rats or Raw264.7 cells with gouty arthritis induced by monosodium urate (MSU) crystal, followed by the detection of TLR4, MyD88, pNF-κB, and NLR family pyrin domain-containing 3 (NLRP3) expression. The swelling of the ankle joint induced by MSU crystal began to be relieved 6 h post the administration with the active flavonoids. In addition, the active flavonoids not only alleviated MSU crystal-induced inflammation in synovial tissues by histopathological examination but also reduced tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1β) levels in the joint tissue fluid of MSU crystal-induced rats. Furthermore, Western blot analysis indicated that the active flavonoids reduced the production of these cytokines by inhibiting the TLR4/MyD88/NF-κB pathway and decreasing NLRP3 expression in synovial tissues of rats. More importantly, the inhibition of TLR4/MyD88/NF-κB pathway and NLRP3 expression was also confirmed in MSU-induced Raw264.7 cells. In conclusion, these results indicated that the active flavonoids from L. brachystachya could effectively attenuate gouty arthritis induced by MSU crystal through the TLR4/MyD88/NF-κB pathway and NLRP3 expression in vivo and in vitro, suggesting several potential candidates for the treatment of gouty arthritis.