Sinomenine Provides Neuroprotection in Model of Traumatic Brain Injury via the Nrf2-ARE Pathway

Bioactivities and Mechanisms of Action of Sinomenine and Its Derivatives: A Comprehensive Review

Sinomenine, an isoquinoline alkaloid extracted from the roots and stems of Sinomenium acutum, has been extensively studied for its derivatives as bioactive agents. This review concentrates on the research advancements in the biological activities and action mechanisms of sinomenine-related compounds until November 2023. The findings indicate a broad spectrum of pharmacological effects, including antitumor, anti-inflammation, neuroprotection, and immunosuppressive properties. These compounds are notably effective against breast, lung, liver, and prostate cancers, exhibiting IC50 values of approximately 121.4 nM against PC-3 and DU-145 cells, primarily through the PI3K/Akt/mTOR, NF-κB, MAPK, and JAK/STAT signaling pathways. Additionally, they manifest anti-inflammatory and analgesic effects predominantly via the NF-κB, MAPK, and Nrf2 signaling pathways. Utilized in treating rheumatic arthritis, these alkaloids also play a significant role in cardiovascular and cerebrovascular protection, as well as organ protection through the NF-κB, Nrf2, MAPK, and PI3K/Akt/mTOR signaling pathways. This review concludes with perspectives and insights on this topic, highlighting the potential of sinomenine-related compounds in clinical applications and the development of medications derived from natural products.

Research Progress on Neuroprotective Effects of Isoquinoline Alkaloids

Neuronal injury and apoptosis are important causes of the occurrence and development of many neurodegenerative diseases, such as cerebral ischemia, Alzheimer's disease, and Parkinson's disease. Although the detailed mechanism of some diseases is unknown, the loss of neurons in the brain is still the main pathological feature. By exerting the neuroprotective effects of drugs, it is of great significance to alleviate the symptoms and improve the prognosis of these diseases. Isoquinoline alkaloids are important active ingredients in many traditional Chinese medicines. These substances have a wide range of pharmacological effects and significant activity. Although some studies have suggested that isoquinoline alkaloids may have pharmacological activities for treating neurodegenerative diseases, there is currently a lack of a comprehensive summary regarding their mechanisms and characteristics in neuroprotection. This paper provides a comprehensive review of the active components found in isoquinoline alkaloids that have neuroprotective effects. It thoroughly explains the various mechanisms behind the neuroprotective effects of isoquinoline alkaloids and summarizes their common characteristics. This information can serve as a reference for further research on the neuroprotective effects of isoquinoline alkaloids.

Sinomenine alleviates lipopolysaccharide-induced acute lung injury via a PPARβ/δ-dependent mechanism

Evidence is mounting that sinomenine and peroxisome proliferator-activated receptor β/δ (PPARβ/δ) are effective against lipopolysaccharide (LPS)-induced acute lung injury (ALI) via anti-inflammatory properties. However, it is unknown whether PPARβ/δ plays a role in the protective effect of sinomenine on ALI. Here, we initially observed that preemptive administration of sinomenine markedly alleviated lung pathological changes, pulmonary edema and neutrophil infiltration, accompanied by inhibition of the expression of the pro-inflammatory cytokines Tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6), which were largely reversed following the addition of a PPARβ/δ antagonist. Subsequently, we also noticed that sinomenine upregulated adenosine A_2A receptor expression in a PPARβ/δ-dependent manner in LPS-stimulated bone marrow-derived macrophages (BMDMs). Further investigation indicated that PPARβ/δ directly bound to the functional peroxisome proliferator responsive element (PPRE) in the adenosine A_2A receptor gene promoter region to enhance the expression of the adenosine A_2A receptor. Sinomenine was identified as a PPARβ/δ agonist. It could bind with PPARβ/δ, and promote the nuclear translocation and transcriptional activity of PPARβ/δ. In addition, combined treatment with sinomenine and an adenosine A_2A receptor agonist exhibited synergistic effects and better protective roles than their single use against ALI. Taken together, our results reveal that sinomenine exerts advantageous effects on ALI by activating of PPARβ/δ, with the subsequent upregulation of adenosine A_2A receptor expression, and provide a novel and potential therapeutic application for ALI.

A review on pharmacokinetics of sinomenine and its anti-inflammatory and immunomodulatory effects

Autoimmune diseases (ADs), with significant effects on morbidity and mortality, are a broad spectrum of disorders featured by body's immune responses being directed against its own tissues, resulting in chronic inflammation and tissue damage. Sinomenine (SIN) is an alkaloid isolated from the root and stem of Sinomenium acutum which is mainly used to treat pain, inflammation and immune disorders for centuries in China. Its potential anti-inflammatory role for treating immune-related disorders in experimental animal models and in some clinical applications have been reported widely, suggesting an inspiring application prospect of SIN. In this review, the pharmacokinetics, drug delivery systems, pharmacological mechanisms of action underlying the anti-inflammatory and immunomodulatory effects of SIN, and the possibility of SIN as adjuvant to disease-modifying anti-rheumatic drugs (DMARDs) therapy were summarized and evaluated. This paper aims to reveal the potential prospects and limitations of SIN in the treatment of inflammatory and immune diseases, and to provide ideas for compensating its limitations and reducing the side effects, and thus to make SIN better translate to the clinic.

Potential therapeutic effects and pharmacological evidence of sinomenine in central nervous system disorders

Sinomenine is a natural compound extracted from the medicinal plant Sinomenium acutum. Its supplementation has been shown to present benefits in a variety of animal models of central nervous system (CNS) disorders, such as cerebral ischemia, intracerebral hemorrhage, traumatic brain injury (TBI), Alzheimer’s disease (AD), Parkinson’s disease (PD), epilepsy, depression, multiple sclerosis, morphine tolerance, and glioma. Therefore, sinomenine is now considered a potential agent for the prevention and/or treatment of CNS disorders. Mechanistic studies have shown that inhibition of oxidative stress, microglia- or astrocyte-mediated neuroinflammation, and neuronal apoptosis are common mechanisms for the neuroprotective effects of sinomenine. Other mechanisms, including activation of nuclear factor E2-related factor 2 (Nrf2), induction of autophagy in response to inhibition of protein kinase B (Akt)-mammalian target of rapamycin (mTOR), and activation of cyclic adenosine monophosphate-response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF), may also mediate the anti-glioma and neuroprotective effects of sinomenine. Sinomenine treatment has also been shown to enhance dopamine receptor D2 (DRD2)-mediated nuclear translocation of αB-crystallin (CRYAB) in astrocytes, thereby suppressing neuroinflammation via inhibition of Signal Transducer and Activator of Transcription 3 (STAT3). In addition, sinomenine supplementation can suppress N-methyl-D-aspartate (NMDA) receptor-mediated Ca²⁺ influx and induce γ-aminobutyric acid type A (GABA_A) receptor-mediated Cl⁻ influx, each of which contributes to the improvement of morphine dependence and sleep disturbance. In this review, we outline the pharmacological effects and possible mechanisms of sinomenine in CNS disorders to advance the development of sinomenine as a new drug for the treatment of CNS disorders.

Sinomenine Attenuates Trimethyltin-Induced Cognitive Decline via Targeting Hippocampal Oxidative Stress and Neuroinflammation

Sinomenine is the main bioactive ingredient of the medicinal plant Sinomenium acutum with neuroprotective potential. This study was designed to assess beneficial effect of sinomenine in alleviation of trimethyltin (TMT)-induced cognitive dysfunction. TMT was administered i.p. (8 mg/kg, once) and sinomenine was daily given p.o. 1 h after TMT for 3 weeks at doses of 25 or 100 mg/kg. Cognitive performance was assessed in various behavioral tests. In addition, oxidative stress- and inflammation-associated factors were measured and histochemical evaluation of the hippocampus was conducted. Sinomenine at a dose of 100 mg/kg significantly and partially increased discrimination index in novel object recognition (NOR), improved alternation in short-term Y maze, increased step-through latency in passive avoidance paradigm, and also reduced probe trial errors and latency in the Barnes maze task. Moreover, sinomenine somewhat prevented inappropriate hippocampal changes of malondialdehyde (MDA), reactive oxygen species (ROS), protein carbonyl, nitrite, superoxide dismutase (SOD), tumor necrosis factor α (TNFα), interleukin 6 (IL 6), acetylcholinesterase (AChE) activity, beta secretase 1 (BACE 1) activity, and mitochondrial membrane potential (MMP) with no significant effect on glutathione (GSH), catalase, glutathione reductase, glutathione peroxidase, and myeloperoxidase (MPO). In addition, lower reactivity (IRA) for glial fibrillary acidic protein (GFAP) as an index of astrocyte activity was observed and loss of CA1 pyramidal neurons was attenuated following sinomenine treatment. This study demonstrated that sinomenine could lessen TMT-induced cognitive dysfunction which is partly due to its attenuation of hippocampal oxidative stress and neuroinflammation.

Immunomodulatory protein from ganoderma microsporum protects against oxidative damages and cognitive impairments after traumatic brain injury

A traumatic brain injury (TBI) causes abnormal proliferation of neuroglial cells, and over-release of glutamate induces oxidative stress and inflammation and leads to neuronal death, memory deficits, and even death if the condition is severe. There is currently no effective treatment for TBI. Recent interests have focused on the benefits of supplements or natural products like Ganoderma. Studies have indicated that immunomodulatory protein from Ganoderma microsporum (GMI) inhibits oxidative stress in lung cancer cells A549 and induces cancer cell death by causing intracellular autophagy. However, no evidence has shown the application of GMI on TBI. Thus, this study addressed whether GMI could be used to prevent or treat TBI through its anti-inflammation and antioxidative effects. We used glutamate-induced excitotoxicity as in vitro model and penetrating brain injury as in vivo model of TBI. We found that GMI inhibits the generation of intracellular reactive oxygen species and reduces neuronal death in cortical neurons against glutamate excitotoxicity. In neurite injury assay, GMI promotes neurite regeneration, the length of the regenerated neurite was even longer than that of the control group. The animal data show that GMI alleviates TBI-induced spatial memory deficits, expedites the restoration of the injured areas, induces the secretion of brain-derived neurotrophic factors, increases the superoxide dismutase 1 (SOD-1) and lowers the astroglial proliferation. It is the first paper to apply GMI to brain-injured diseases and confirms that GMI reduces oxidative stress caused by TBI and improves neurocognitive function. Moreover, the effects show that prevention is better than treatment. Thus, this study provides a potential treatment in naturopathy against TBI.

Targeting Nrf2-Mediated Oxidative Stress Response in Traumatic Brain Injury: Therapeutic Perspectives of Phytochemicals

Traumatic brain injury (TBI), known as mechanical damage to the brain, impairs the normal function of the brain seriously. Its clinical symptoms manifest as behavioral impairment, cognitive decline, communication difficulties, etc. The pathophysiological mechanisms of TBI are complex and involve inflammatory response, oxidative stress, mitochondrial dysfunction, blood-brain barrier (BBB) disruption, and so on. Among them, oxidative stress, one of the important mechanisms, occurs at the beginning and accompanies the whole process of TBI. Most importantly, excessive oxidative stress causes BBB disruption and brings injury to lipids, proteins, and DNA, leading to the generation of lipid peroxidation, damage of nuclear and mitochondrial DNA, neuronal apoptosis, and neuroinflammatory response. Transcription factor NF-E2 related factor 2 (Nrf2), a basic leucine zipper protein, plays an important role in the regulation of antioxidant proteins, such as oxygenase-1(HO-1), NAD(P)H Quinone Dehydrogenase 1 (NQO1), and glutathione peroxidase (GPx), to protect against oxidative stress, neuroinflammation, and neuronal apoptosis. Recently, emerging evidence indicated the knockout (KO) of Nrf2 aggravates the pathology of TBI, while the treatment of Nrf2 activators inhibits neuronal apoptosis and neuroinflammatory responses via reducing oxidative damage. Phytochemicals from fruits, vegetables, grains, and other medical herbs have been demonstrated to activate the Nrf2 signaling pathway and exert neuroprotective effects in TBI. In this review, we emphasized the contributive role of oxidative stress in the pathology of TBI and the protective mechanism of the Nrf2-mediated oxidative stress response for the treatment of TBI. In addition, we summarized the research advances of phytochemicals, including polyphenols, terpenoids, natural pigments, and otherwise, in the activation of Nrf2 signaling and their potential therapies for TBI. Although there is still limited clinical application evidence for these natural Nrf2 activators, we believe that the combinational use of phytochemicals such as Nrf2 activators with gene and stem cell therapy will be a promising therapeutic strategy for TBI in the future.

Considerations about Hypoxic Changes in Neuraxis Tissue Injuries and Recovery

Hypoxia represents the temporary or longer-term decrease or deprivation of oxygen in organs, tissues, and cells after oxygen supply drops or its excessive consumption. Hypoxia can be (para)-physiological-adaptive-or pathological. Thereby, the mechanisms of hypoxia have many implications, such as in adaptive processes of normal cells, but to the survival of neoplastic ones, too. Ischemia differs from hypoxia as it means a transient or permanent interruption or reduction of the blood supply in a given region or tissue and consequently a poor provision with oxygen and energetic substratum-inflammation and oxidative stress damages generating factors. Considering the implications of hypoxia on nerve tissue cells that go through different ischemic processes, in this paper, we will detail the molecular mechanisms by which such structures feel and adapt to hypoxia. We will present the hypoxic mechanisms and changes in the CNS. Also, we aimed to evaluate acute, subacute, and chronic central nervous hypoxic-ischemic changes, hoping to understand better and systematize some neuro-muscular recovery methods necessary to regain individual independence. To establish the link between CNS hypoxia, ischemic-lesional mechanisms, and neuro-motor and related recovery, we performed a systematic literature review following the" Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA") filtering method by interrogating five international medical renown databases, using, contextually, specific keywords combinations/"syntaxes", with supplementation of the afferent documentation through an amount of freely discovered, also contributive, bibliographic resources. As a result, 45 papers were eligible according to the PRISMA-inspired selection approach, thus covering information on both: intimate/molecular path-physiological specific mechanisms and, respectively, consequent clinical conditions. Such a systematic process is meant to help us construct an article structure skeleton giving a primary objective input about the assembly of the literature background to be approached, summarised, and synthesized. The afferent contextual search (by keywords combination/syntaxes) we have fulfilled considerably reduced the number of obtained articles. We consider this systematic literature review is warranted as hypoxia's mechanisms have opened new perspectives for understanding ischemic changes in the CNS neuraxis tissue/cells, starting at the intracellular level and continuing with experimental research to recover the consequent clinical-functional deficits better.

Neuroprotective effects of auraptene following traumatic brain injury in male rats: The role of oxidative stress

AIM

Traumatic Brain Injury (TBI) is widely acknowledged as a significant risk factor for death and disability. Our goal in this experiment was to see if Auraptene (AUR) could help rats recover from TBI-induced disability by measuring of oxidative stress parameters.

MATERIAL AND METHODS

Adult male Wistar rats were randomly assigned to one of six groups: sham, TBI, Vehicle (DMSO), TBI+ AUR (4 mg/kg), TBI + AUR (8 mg/kg), TBI + AUR (25 mg/kg). The animals were anesthetized. After that, diffuse TBI was done by Marmarou model in male rats. Then, the brain tissues were harvested. Some of oxidative stress parameters, and TNFα levels were evaluated.

RESULTS

TBI-induced brain damage was significantly inhibited by AUR (25 mg/kg), as evidenced by decreased Malondialdehyde (MDA) and Nitric Oxide (NO) levels, oxidative stress inhibition and reduced levels of pro-inflammatory cytokine tumor necrosis factor (TNF-α) in the brain.

CONCLUSION

This study showed that probably the AUR prevents complications of TBI through decreases in brain edema, modulating oxidative stress, and reductions in the levels of inflammatory cytokines.

Promise of the NLRP3 Inflammasome Inhibitors in In Vivo Disease Models

Nucleotide-binding oligomerization domain NOD-like receptors (NLRs) are conserved cytosolic pattern recognition receptors (PRRs) that track the intracellular milieu for the existence of infection, disease-causing microbes, as well as metabolic distresses. The NLRP3 inflammasome agglomerates are consequent to sensing a wide spectrum of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). Certain members of the NLR family have been documented to lump into multimolecular conglomerates called inflammasomes, which are inherently linked to stimulation of the cysteine protease caspase-1. Following activation, caspase-1 severs the proinflammatory cytokines interleukin (IL)-1β and IL-18 to their biologically active forms, with consequent commencement of caspase-1-associated pyroptosis. This type of cell death by pyroptosis epitomizes a leading pathway of inflammation. Accumulating scientific documentation has recorded overstimulation of NLRP3 (NOD-like receptor protein 3) inflammasome involvement in a wide array of inflammatory conditions. IL-1β is an archetypic inflammatory cytokine implicated in multiple types of inflammatory maladies. Approaches to impede IL-1β's actions are possible, and their therapeutic effects have been clinically demonstrated; nevertheless, such strategies are associated with certain constraints. For instance, treatments that focus on systemically negating IL-1β (i.e., anakinra, rilonacept, and canakinumab) have been reported to result in an escalated peril of infections. Therefore, given the therapeutic promise of an NLRP3 inhibitor, the concerted escalated venture of the scientific sorority in the advancement of small molecules focusing on direct NLRP3 inflammasome inhibition is quite predictable.

Cellular Mechanisms Participating in Brain Repair of Adult Zebrafish and Mammals after Injury

Adult neurogenesis is an evolutionary conserved process occurring in all vertebrates. However, striking differences are observed between the taxa, considering the number of neurogenic niches, the neural stem cell (NSC) identity, and brain plasticity under constitutive and injury-induced conditions. Zebrafish has become a popular model for the investigation of the molecular and cellular mechanisms involved in adult neurogenesis. Compared to mammals, the adult zebrafish displays a high number of neurogenic niches distributed throughout the brain. Furthermore, it exhibits a strong regenerative capacity without scar formation or any obvious disabilities. In this review, we will first discuss the similarities and differences regarding (i) the distribution of neurogenic niches in the brain of adult zebrafish and mammals (mainly mouse) and (ii) the nature of the neural stem cells within the main telencephalic niches. In the second part, we will describe the cascade of cellular events occurring after telencephalic injury in zebrafish and mouse. Our study clearly shows that most early events happening right after the brain injury are shared between zebrafish and mouse including cell death, microglia, and oligodendrocyte recruitment, as well as injury-induced neurogenesis. In mammals, one of the consequences following an injury is the formation of a glial scar that is persistent. This is not the case in zebrafish, which may be one of the main reasons that zebrafish display a higher regenerative capacity.

Counteracting role of nuclear factor erythroid 2-related factor 2 pathway in Alzheimer's disease

A salient pathological features in Alzheimer's disease includes redox impairment and neuroinflammation. Nuclear factor erythroid 2-related factor 2 (Nrf2) and Nuclear factor kappa B (NF-ҡB) are the two key transcription factors that regulate cellular responses to redox impairment and neuroinflammation respectively. An effective way to confer neuroprotection in central nervous system (CNS) is the activation of a transcription factor i.e Nuclear factor erythroid 2-related factor 2 (Nrf2). An enhancer element known as Antioxidant Response Element (ARE) mediates the expression of phase II detoxification enzymes. Nrf2 is a nuclear transcription factor that binds to ARE thereby transcribing expression of several antioxidant genes. Kelch ECH associating protein-1 (Keap1), a culin 3-based E3 ligase, polyubiquitinates Nrf2 and targets it for its degradation. Disruption in the interaction between Keap1/Nrf2 can increase the brain's endogenous antioxidant capacity and thereby responsible for cell defence against oxidative stress and neuroinflammation in Alzheimer's disease (AD). The current review discusses about Keap1-Nrf2-ARE structure and function with special emphasis on the various pathways involved in positive and negative modulation of Nrf2, namely Phosphoinositide 3- kinase (PI3K), Glycogen synthase kinase-3β (GSK-3β), Nuclear factor kappa-b (NF-ҡb), Janus kinase/signal transducer and activator of transcription (JAK-STAT),Tumour Necrosis Factor- α (TNF-α), p38Mitogen-activated protein kinases (p38MAPK), Cyclic AMP response element binding protein (CREB) and intrinsic & extrinsic apoptotic pathway. Furthermore, this review highlights the miscellaneous Nrf2 activators as promising therapeutic agents for slowingdown the progression of AD.

Neuroprotective and anticonvulsant effects of sinomenine in kainate rat model of temporal lobe epilepsy: Involvement of oxidative stress, inflammation and pyroptosis

Oxidative stress, inflammation and pyroptosis are three of the most important mechanisms in the pathophysiology of temporal lobe epilepsy (TLE). Most people with TLE are refractory to the existing drugs. Sinomenine has shown neuroprotective effects through counteracting oxidative stress, inflammation and pyroptosis. In this study, we evaluated the effect of sinomenine on seizure behavior, oxidative stress, inflammation and pyroptosis markers in addition to its neuroprotective potential in intrahippocampal kainate-induced rat model of TLE. For this purpose, male rats (n = 60) were randomly divided into five groups, i.e., sham, kainate (lesion) with an intrahippocampal injection of kainate, kainate groups receiving sinomenine at doses of 30 or 50 mg/kg, and kainate group receiving valproic acid at a dose of 200 mg/kg (as the positive control). Our obtained data showed that sinomenine administration at a dose of 50 mg/kg can significantly decreases severity of seizures and incidence of status epilepticus (SE), hippocampal aberrant MFS and DNA fragmentation and prevents reduction of neuronal density. It also significantly restored level of ROS, MDA, HO-1 and SOD but its effect on GSH level was not significant. Additionally, sinomenine at a dose of 50 mg/kg partially counteracted the increase of NF-κB, TLR 4, TNFα, GFAP and caspase 1. These results suggest that sinomenine has anticonvulsant and neuroprotective effects by reducing hippocampal oxidative stress, inflammation, pyroptosis and apoptosis in intrahippocampal kainate model of TLE.

Xiaochaihutang Improves the Cortical Astrocyte Edema in Thioacetamide-Induced Rat Acute Hepatic Encephalopathy by Activating NRF2 Pathway

Oxidative stress induced by high ammonia, which leads to astrocyte edema, is the key to acute hepatic encephalopathy (AHE). Nuclear factor erythroid 2-related factor 2 (NRF2) has been implicated in oxidative stress, but the mechanism of NRF2 against ammonia-induced astrocytes edema has not been fully studied. We confirmed that the NRF2 pathway is related to brain edema caused by AHE and found that Xiaochaihutang (XCHT) could effectively activate the NRF2 pathway to treat AHE. The model of AHE was established with thioacetamide (TAA) in rats. Rat behaviors were observed, brain water content, blood ammonia levels, glutamine synthetase (GS), malondialdehyde (MDA), and total superoxide dismutase (T-SOD) were determined after XCHT treatment. Furthermore, the expression of NRF2 pathway proteins and mRNA, glial fibrillary acidic protein (GFAP) and aquaporins 4 (AQP4) were examined. In order to determine whether XCHT has a direct effect on cerebral edema caused by high ammonia, we examined the effect of XCHT compound serum on cortical astrocytes in the presence of ammonia, through microscopic observation and immunofluorescence (IF). Results showed that AHE induced by TAA changed the behavior of the rats, and increased brain water content, blood ammonia levels, GS and MDA content meanwhile decreasing T-SOD, but these symptoms were improved by treatment with XCHT. XCHT protected brain edema by activating the NRF2 pathway and increasing the expression of downstream proteins and genes. Astrocytes treated with 5 mM ammonia also showed an increase in the AQP4 protein expression but a decrease in XCHT compound serum and ammonia-induced cell edema groups. This study demonstrates that the NRF2 pathway is involved in the brain edema in AHE, and XCHT may represent a useful prescription for the treatment of AHE.

Melatonin receptor activation provides cerebral protection after traumatic brain injury by mitigating oxidative stress and inflammation via the Nrf2 signaling pathway

Traumatic brain injury (TBI) is a principal cause of death and disability worldwide. Melatonin, a hormone made by the pineal gland, is known to have anti-inflammatory and antioxidant properties. In this study, using a weight-drop model of TBI, we investigated the protective effects of ramelteon, a melatonin MT1/MT2 receptor agonist, and its underlying mechanisms of action. Administration of ramelteon (10 mg/kg) daily at 10:00 a.m. alleviated TBI-induced early brain damage on day 3 and long-term neurobehavioral deficits on day 28 in C57BL/6 mice. Ramelteon also increased the protein levels of interleukin (IL)-10, IL-4, superoxide dismutase (SOD), glutathione, and glutathione peroxidase and reduced the protein levels of IL-1β, tumor necrosis factor, and malondialdehyde in brain tissue and serum on days 1, 3, and 7 post-TBI. Similarly, ramelteon attenuated microglial and astrocyte activation in the perilesional cortex on day 3. Furthermore, ramelteon decreased Keap 1 expression, promoted nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear accumulation, and increased levels of downstream proteins, including SOD-1, heme oxygenase-1, and NQO1 on day 3 post-TBI. However, in Nrf2 knockout mice with TBI, ramelteon did not decrease the lesion volume, neuronal degeneration, or myelin loss on day 3; nor did it mitigate depression-like behavior or most motor behavior deficits on day 28. Thus, timed ramelteon treatment appears to prevent inflammation and oxidative stress via the Nrf2-antioxidant response element pathway and might represent a potential chronotherapeutic strategy for treating TBI.

Docosahexaenoic Acid (DHA) Provides Neuroprotection in Traumatic Brain Injury Models via Activating Nrf2-ARE Signaling

In this study, we explored the neuroprotective effects of docosahexaenoic acid (DHA) in traumatic brain injury (TBI) models. In this study, we first confirmed that DHA was neuroprotective against TBI via the NSS test and Morris water maze experiment. Western blot was conducted to identify the expression of Bax, caspase-3, and Bcl-2. And the cell apoptosis of the TBI models was validated by TUNEL staining. Relationships between nuclear factor erythroid 2-related factor 2-antioxidant response element (Nrf2-ARE) pathway-related genes and DHA were explored by RT-PCR and Western blot. Rats of the DHA group performed remarkably better than those of the TBI group in both NSS test and water maze experiment. DHA conspicuously promoted the expression of Bcl-2 and diminished that of cleaved caspase-3 and Bax, indicating the anti-apoptotic role of DHA. Superoxide dismutase (SOD) activity and cortical malondialdehyde content, glutathione peroxidase (GPx) activity were renovated in rats receiving DHA treatment, implying that the neuroprotective influence of DHA was derived from lightening the oxidative stress caused by TBI. Moreover, immunofluorescence and Western blot experiments revealed that DHA facilitated the translocation of Nrf2 to the nucleus. DHA administration also notably increased the expression of the downstream factors NAD(P)H:quinone oxidoreductase (NQO-1) and heme oxygenase 1(HO-1). DHA exerted neuroprotective influence on the TBI models, potentially through activating the Nrf2- ARE pathway.

Baicalin provides neuroprotection in traumatic brain injury mice model through Akt/Nrf2 pathway

Background

The neuroprotective effects of Baicalin have been confirmed in several central nervous system (CNS) diseases. However, its possible effect on traumatic brain injury (TBI) model is still not clear. The present study is aimed to investigate the role and the underling mechanisms of 7-D-glucuronic acid-5,6-dihydroxyflavone (Baicalin) on TBI model.

Methods

The weight-drop model of TBI in Institute of Cancer Research mice was treated with Baicalin intraperitoneally at 30 minutes after TBI. LY294002 (LY) (a commonly used PI3K/Akt pathway inhibitor) was injected into the left ventricle at 30 minutes before TBI. All mice were euthanized at 24 hours after TBI to collect the brain tissue for a series of tests except for neurological function, which was measured at 2 hours and 1 and 3 days post-TBI.

Results

Baicalin administration significantly improved neurobehavioral function, alleviated brain edema, and reduced apoptosis-positive cells by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay accompanied with the upregulation of B-cell lymphoma 2 (Bcl-2) and downregulation of Bcl-2-associated X protein (Bax) and cleaved-caspase 3 by Western blot. Besides, TBI-induced oxidant stress status was also restored in the Baicalin group by measuring malondialdehyde (MDA) content, glutathione peroxidase (GPx), and superoxide dismutase (SOD) levels in the injured brain cortex. Furthermore, translocation of Nrf2 to the nucleus was dramatically enhanced by Baicalin verified by immunofluorescence and Western blot analyses. Accordingly, its downstream antioxidative enzymes nicotinamide adenine dinucleotide phosphate:quinine oxidoreductase 1 (NQO-1) and heme oxygenase 1 (HO-1) were also activated by Baicalin confirmed by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blot. However, cotreatment with Baicalin and LY could partly abolish Baicalin-induced activation of Nrf2 and its neuroprotective effects in TBI.

Conclusion

This study demonstrates that Baicalin provides a neuroprotective effect in TBI mice model via activating the Akt/Nrf2 pathway.

Ischemic Postconditioning Alleviates Cerebral Ischemia-Reperfusion Injury Through Activating Autophagy During Early Reperfusion in Rats

This study aimed to investigate whether ischemic postconditioning (IpostC) alleviates cerebral ischemia/reperfusion (I/R) injury involved in autophagy. Adult Sprague–Dawley rats were divided into five groups: sham (sham surgery), I/R (middle cerebral artery occlusion [MCAO] for 100 min, then reperfusion), IpostC (MCAO for 100 min, reperfusion for 10 min, MCAO for 10 min, then reperfusion), IpostC+3MA (3-methyladenine, an autophagy inhibitor, administered 30 min before first reperfusion), and IpostC+Veh (vehicle control for IpostC+3MA group). Infarct volume was measured using cresyl violet staining. Autophagy-related proteins were detected by western blot and immunohistochemistry. Autophagosomes, autophagolysosomes, and mitochondrial damage were identified by transmission electron microscopy. Cortical cell apoptosis was detected by the TUNEL assay. Neurologic function was assessed using the modified Neurologic Severity Score. IpostC improved neurological function and reduced infarct volume after I/R (P < 0.05). These effects of IpostC were inhibited by 3MA (P < 0.05). Autophagosome formation was increased in the I/R and IpostC+Veh groups (P < 0.05), but not in the IpostC+3MA group. The I/R group showed enhanced LC3-II/LC3-I ratio, p62, and Cathepsin B levels and decreased LAMP-2 level (all P < 0.05 vs. sham), indicating dysfunction of autophagic clearance. IpostC reduced p62 and Cathepsin B levels and increased the LC3-II/LC3-I ratio, and nuclear translocation of transcription factor EB (all P < 0.05); these effects of IpostC were reversed by 3MA, suggesting IpostC enhanced autophagic flux. Furthermore, IpostC attenuated I/R-induced mitochondrial translocation of Bax and mitochondrial cytochrome-c release (all P < 0.05); 3MA inhibited these effects of IpostC (P < 0.05). In conclusion, IpostC may alleviate cerebral I/R injury by activating autophagy during early reperfusion.

Protective Effects of Sinomenine Against Ankylosing Spondylitis and the Underlying Molecular Mechanisms

BACKGROUND This study aimed to investigate the effect and underlying molecular mechanism of sinomenine (SIN) on ankylosing spondylitis (AS). MATERIAL AND METHODS To study the potential role of SIN in the pathogenesis of AS, an AS mouse model was established and mice were treated with different concentrations of SIN (10, 30, and 50 mg/kg, administered intraperitoneally). Markers of inflammation and oxidative stress were determined by ELISA assay. Western blot analysis and qRT-PCR were used to quantify the levels of related proteins and gene mRNA expression. RESULTS The results suggest that AS mice has higher levels of TNF-α, IL-1β, and IL-6 (p<0.01 for all), and lower levels of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-PX) (p<0.01 for all). SIN treatment reduced the level of TNF-α, IL-1β, and IL-6 in a dose-dependent manner, and the levels of SOD, CAT, and GSH-PX were dose-dependently increased (p<0.05 for all). The results also revealed that NF-κBp65 expression decreased, while the level of IkB increased, in a dose-dependent manner, after SIN treatment in AS mice (p<0.05 for all). The level of p-p38 was dose-dependently reduced in AS mice by SIN treatment (p<0.05). Moreover, SIN inhibited Cox-2 expression in AS mice in a dose-dependent manner (p<0.05). CONCLUSIONS SIN has a beneficial role in AS through suppressing inflammatory mediators and by down-regulating oxidative stress via inhibiting the MAPKp38/NF-kB pathway and Cox-2 expression.

Protective Effects of Sinomenine on CFA-Induced Inflammatory Pain in Rats

Background

The purpose of this study was to investigate the effects of sinomenine (SIN) on CFA-induced inflammatory pain in rats, and to explore the underlying molecular mechanisms.

Material/Methods

To determine the potential influences of SIN in the pathogenesis of inflammatory pain, an inflammatory pain (IP) mouse model was established and rats were treated with SIN (30 mg/kg). Behavioral tests were used to assess the MWT and TWL of the rats. ELISA assay was used to detect the level of inflammation cytokines. Western blotting and qRT-PCR were carried out to measure the related protein and mRNA expression level, respectively.

Results

We found that the MWT and TWL of the CFA-treated rats were markedly lower than that of the control rats, and they were significantly increased by SIN administration. The results suggest that IP rats had higher levels of TNF-α, IL-1β and IL-6 compared with the control rats. SIN administration decreased the levels of TNF-α, IL-1β, and IL-6. In addition, we found that p-p65 and p-p38 expression notably decreased after SIN treatment in IP rats. Moreover, the results showed that SIN inhibited Cox-2 and PGE2 expression in IP rats.

Conclusions

The data indicate that SIN had a protective role in inflammatory pain through repressing inflammatory mediators via preventing the p38MAPK-NF-κB pathway.

Sinomenine reduces neuronal cell apoptosis in mice after traumatic brain injury via its effect on mitochondrial pathway

Background

Sinomenine (SIN) has been shown to have protective effects against brain damage following traumatic brain injury (TBI). However, the mechanisms and its role in these effects remain unclear. This study was conducted to investigate the potential mechanisms of the protective effects of SIN.

Methods

The weight-drop model of TBI in Institute of Cancer Research (ICR) mice were treated with SIN or a vehicle via intraperitoneal administration 30 min after TBI. All mice were euthanized 24 h after TBI and after neurological scoring, a series of tests were performed, including brain water content and neuronal cell death in the cerebral cortex.

Results

The level of cytochrome c (Cyt c), malondialdehyde (MDA), glutathione peroxidase (GPx) and superoxide dismutase 1 (SOD) were restored to some degree following the SIN treatment. The SIN treatment significantly decreased caspase-3 expression and reduced the number of positive cells by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay and improved the survival of neuronal cells. Additionally, the pretreatment levels of MDA were restored, while Bax translocation to mitochondria and Cyt c release into the cytosol were reduced by the SIN treatment.

Conclusion

SIN protected neuronal cells by protecting them against apoptosis via mechanisms that involve the mitochondria following TBI.

Inhibiting Inflammasomes with Small Molecules

Modulation of inflammasomes has tremendous therapeutic potential and is hotly pursued by industry and academia alike. Indeed a growing number of patents are emerging to protect the intellectual property in valuable compound classes. This chapter focusses specifically on the suite of small-molecule NLRP3 inflammasome inhibitors published, as specific modulation of other inflammasomes is not yet well established. Synthetic molecules, known drugs and natural product NLRP3 modulators will be detailed. Some of the molecular classes discussed have been extensively characterised through cell-based screening, pharmacokinetic profiling and therapeutic proof of concept animal models. However, many inhibitors lack rigorous studies and/or have multiple activities of which NLRP3 modulation is only one. While this is not intended as an exhaustive list, it should give an impression of the range of structures and strategies that are being used, alongside challenges encountered, in an effort to exploit the significant therapeutic benefits of targeting inflammasomes.

Rosmarinic acid elicits neuroprotection in ischemic stroke via Nrf2 and heme oxygenase 1 signaling

Rosmarinic acid (RA) can elicit a neuroprotective effect against ischemic stroke, but the precise molecular mechanism remains poorly understood. In this study, an experimental ischemic stroke model was established in CD-1 mice (Beijing Vital River Laboratory Animal Technology, Beijing, China) by occluding the right middle cerebral artery for 1 hour and allowing reperfusion for 24 hours. After intraperitoneally injecting model mice with 10, 20, or 40 mg/kg RA, functional neurological deficits were evaluated using modified Longa scores. Subsequently, cerebral infarct volume was measured using TTC staining and ischemic brain tissue was examined for cell apoptosis with TUNEL staining. Superoxide dismutase activity and malondialdehyde levels were measured by spectrophometry. Expression of heme oxygenase-1 (HO-1), nuclear factor erythroid 2-related factor 2 (Nrf2), Bcl-2, Bax, Akt, and phospho-Ser473 Akt proteins in ischemic brain tissue was detected by western blot, while mRNA levels of Nrf2, HO-1, Bcl-2, and Bax were analyzed using real time quantitative PCR. In addition, HO-1 enzyme activity was measured spectrophotometrically. RA (20 and 40 mg/kg) greatly improved neurological function, reduced infarct volume, decreased cell apoptosis, upregulated Bcl-2 protein and mRNA expression, downregulated Bax protein and mRNA expression, increased HO-1 and Nrf2 protein and mRNA expression, increased superoxide dismutase activity, and decreased malondialdehyde levels in ischemic brain tissue of model mice. However, intraperitoneal injection of a HO-1 inhibitor (10 mg/kg zinc protoporphyrin IX) reversed the neuroprotective effects of RA on HO-1 enzyme activity and Bcl-2 and Bax protein expression. The PI3K/Akt signaling pathway inhibitor LY294002 (10 mM) inhibited Akt phosphorylation, as well as Nrf2 and HO-1 expression. Our findings suggest that RA has anti-oxidative and anti-apoptotic properties that protect against ischemic stroke by a mechanism involving upregulation of Nrf2 and HO-1 expression via the PI3K/Akt signaling pathway.

Increased miR-155 and heme oxygenase-1 expression is involved in the protective effects of formononetin in traumatic brain injury in rats

Oxidative stress has been considered a major contributing factor to traumatic brain injury (TBI). Formononetin, a phytoestrogen that belongs to the flavonoid family, is extracted from plants and herbs such as the red clover. Growing evidence demonstrates that formononetin has antioxidant properties. Therefore, formononetin has potential use in treating oxidative stress injuries in TBI. In this study, the neuroprotective and antioxidant effects of formononetin against TBI, as well as the related probable mechanisms, were investigated. The TBI model was produced in male Wistar rats through Feeney's weight-drop model. At 1 day after TBI, the neurological function score and brain water content were assessed. TUNEL assay was used to determine neuronal apoptosis. The expression levels of miR-155, HO-1, and BACH1 were measured by RT-PCR and western blotting. Consequently, our findings showed that formononetin pretreatment for 5 days significantly improved the neurological scores, reduced brain edema and inhibited neuronal apoptosis in rats after TBI. MiR-155 was substantially decreased and BACH1 expression was significantly increased in the TBI model, while pretreatment with formononetin dramatically up-regulated the expression levels of miR-155 and HO-1 and down-regulated the protein expression of BACH1 in rats after TBI. In summary, formononetin has been shown to have neuroprotective effects, and the mechanisms of this effect may be associated with its inhibition of oxidative stress and activation of Nrf2-dependent antioxidant pathways in TBI.

Targeting the NF-E2-Related Factor 2 Pathway: a Novel Strategy for Traumatic Brain Injury

As an essential component of cellular defense against a variety of endogenous and exogenous stresses, nuclear factor erythroid 2-related factor 2 (Nrf2) has received increased attention in the past decades. Multiple studies indicate that Nrf2 acts not only as an important protective factor in injury models but also as a downstream target of therapeutic agents. Activation of Nrf2 has increasingly been linked to many human diseases, especially in central nervous system (CNS) injury such as traumatic brain injury (TBI). Several researches have deciphered that activation of Nrf2 exerts antioxidative stress, antiapoptosis, and antiinflammation influence in TBI via different molecules and pathways including heme oxygenase-1 (HO-1), NADPH:quinine oxidoreductase-1 (NQO-1), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2). Hence, Nrf2 shows great promise as a molecular target in TBI. In the present article, we provide an updated review of the current state of our knowledge about relationship between Nrf2 and TBI, highlighting the specific roles of Nrf2 in TBI.