Attenuation of neuropathic pain and neuroinflammatory responses by a pyranocoumarin derivative, anomalin in animal and cellular models

Immunostimulant, hepatoprotective, and nephroprotective potential of Bacillus subtilis (NMCC-path-14) in comparison to dexamethasone in alleviating CFA-induced arthritis

To investigate and compare efficacy as well as safety of Bacillus subtilis and dexamethasone (Dexa) in complete Freund's adjuvant (CFA)-induced arthritis, we used glucocorticoid monotherapy (Dexa 5 mg/kg/day) and B. subtilis (1 × 108 CFU/animal/day p.o) as pre-treatment and concurrent treatment for a duration of 35 days. Specific emphasis was on chronic aspect of this study since long-term use of Dexa is known to produce undesirable side effects. Treatment with Dexa significantly attenuated the arthritic symptoms but produced severe side effects like weight loss, increased mortality, immunosuppression, and altered histology of liver, kidney, and spleen. Oxidative stress was also elevated by Dexa in these organs which contributed to the damage. Treatment with B. subtilis improved symptoms of arthritis without producing any deleterious side effects as seen with Dexa therapy. Immunohistochemistry (IHC) profile revealed decreased expression of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), interleukin (IL)-1β, tumor necrosis factor alpha (TNF-α), and increased nuclear factor erythroid 2-related factor 2 (Nrf-2) expression by B. subtilis and Dexa treatment in ankle joint of arthritic mice. Radiological scores were also improved by both treatments. This study concludes that B. subtilis could be an effective alternative for treating arthritis than Dexa since it does not produce life-threatening side effects on prolong treatment.

Preparation, characterization, and pharmacological application of oral Honokiol-loaded solid lipid nanoparticles for diabetic neuropathy

Honokiol is a phytochemical component with a variety of pharmacological properties. However, the major limitation of Honokiol is its poor solubility and low oral bioavailability. In this study, we formulated and characterized oral Honokiol-loaded solid lipid nanoparticles (SLNs) to enhance bioavailability and then evaluated their effectiveness in experimental diabetic neuropathy (DN). The finalized formulation has a spherical morphology, a particle size (PS) of 121.31 ± 9.051 nm, a polydispersity index (PDI) of 0.249 ± 0.002, a zeta potential (ZP) of -20.8 ± 2.72 mV, and an entrapment efficiency (% EE) of 88.66 ± 2.30 %. In-vitro release data shows, Honokiol-SLNs displayed a sustained release profile at pH (7.4). The oral bioavailability of Honokiol-SLNs was remarkably greater (8-fold) than Honokiol-Pure suspension. The neuroprotective property of Honokiol-SLNs was initially demonstrated against hydrogen peroxide H2O2-stimulated PC12 (pheochromocytoma) cells. Furthermore, results of in-vivo studies demonstrated that treatment with Honokiol-SLNs significantly (p < 0.001) suppressed oxidative stress by inhibition of nuclear factor kappa B (NF-κB) and significant (p < 0.001) upregulation of nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling in the spinal cord. The expression of transient receptor potential melastatin 8(TRPM8) and transient receptor potential vanilloid 1 (TRPV1) was significantly (p < 0.001) downregulated. Honokiol-SLNs inhibited apoptosis by significant (p < 0.001) downregulation of cleaved caspase-3 expression in the spinal cord. These findings demonstrate that Honokiol-SLNs providedbetter neuroprotection in DN because of higher oral bioavailability.

Multicomponent Synthesis Strategies, Catalytic Activities, and Potential Therapeutic Applications of Pyranocoumarins: A Comprehensive Review

Fused coumarins, because of their remarkable biological and therapeutic properties, particularly pyranocoumarins, have caught the interest of synthetic organic chemists, leading to the development of more efficient and environmentally friendly protocols for synthesizing pyranocoumarin derivatives. These compounds are the most promising heterocycles discovered in both natural and synthetic sources, with anti-inflammatory, anti-HIV, antitubercular, antihyperglycemic, and antibacterial properties. This review employed the leading scientific databases Scopus, Web of Science, Google Scholar, and PubMed up to the end of 2022, as well as the combining terms pyranocoumarins, synthesis, isolation, structural elucidation, and biological activity. Among the catalysts employed, acidic magnetic nanocatalysts, transition metal catalysts, and carbon-based catalysts have all demonstrated improved reaction yields and facilitated reactions under milder conditions. Herein, the present review discusses the various multicomponent synthetic strategies for pyranocoumarins catalyzed by transition metal-based catalysts, transition metal-based nanocatalysts, transition metal-free catalysts, carbon-based nanocatalysts, and their potential pharmacological activities.

Daidzein attenuated paclitaxel-induced neuropathic pain via the down-regulation of TRPV1/P2Y and up-regulation of Nrf2/HO-1 signaling

Paclitaxel (PTX) is an anti-microtubule agent, used for the treatment of various types of cancers; however, it produces painful neuropathy which limits its use. Many neuroprotective agents have been introduced to mitigate PTX-induced neuropathic pain (PINP), but they pose many adverse effects. The purpose of this study was to evaluate the pharmacological characteristics of soy isoflavone, and daidzein (DZ) in attenuating PINP. At the beginning of the investigation, the effect of DZ was confirmed through behavioral analysis, as it reduced pain hypersensitivity. Moreover, changes in the histological parameters were reversed by DZ administration along with vascular permeability. PTX administration upregulated transient receptor potential vanilloid 1 (TRPV1) channels and purinergic receptors (P2Y), contributing to hyperalgesia; but administration of DZ downregulated the TRPV1 and P2Y, thus reducing hyperalgesia. DZ increased nuclear factor erythroid-2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), playing a pivotal role in the activation of the antioxidant pathway. DZ also decreased neuronal apoptosis by decreasing caspase-3 and Bcl2-associated X-protein (Bax), while simultaneously, increasing Bcl-2. PTX administration produced severe DNA damage, which was mitigated by DZ. Similarly, DZ administration resulted in inhibition of neuroinflammation by increasing antioxidant enzymes and reducing oxidative stress markers. PTX caused increased in production of pro-inflammatory mediators such as the cytokines production, while DZ inhibited the pro-inflammatory mediators. Additionally, in silico pharmacokinetic and toxicodynamic study of DZ was also conducted. In summary, DZ demonstrated significant neuroprotective activity against PTX induced neuropathic pain.

New advances in Nrf2-mediated analgesic drugs

BACKGROUND

Oxidative stress is an inevitable process that occurs during life activities, and it can participate in the development of inflammation. Although great progress has been made according to research examining analgesic drugs and therapies, there remains a need to develop new analgesic drugs to fill certain gaps in both the experimental and clinical space.

PURPOSE

This review reports the research and preclinical progress of this class of analgesics by summarizing known nuclear factor E-2-related factor-2 (Nrf2) pathway-modulating substances.

STUDY DESIGN

We searched and reported experiments that intervene in the Nrf2 pathway and its various upstream and downstream molecules for analgesic therapy.

METHODS

The medical literature database (PubMed) was searched for experimental studies examining the reduction of pain in animals through the Nrf2 pathway, the research methods were analyzed, and the pathways were classified and reported according to the pathway of these experimental interventions.

RESULTS

Humans have identified a variety of substances that can fight pain by regulating the expression of Nrf2 and its upstream and downstream pathways.

CONCLUSION

The Nrf2 pathway exerts anti-inflammatory activity by regulating oxidative stress, thereby playing a role in the fight against pain.

Potential applications of PEGylated green gold nanoparticles in cyclophosphamide-induced cystitis

We investigated the effect of green tea extract PEGylated gold nanoparticles (P-AuNPs) making use of its targeted and sustained drug delivery against cyclophosphamide (CYP)-induced cystitis. AuNPs were synthesized by reduction reaction of gold salts with green tea extract following the concept of green synthesis. Mostly spherical-shaped P-AuNPs were synthesized with an average size of 14.3 ± 3.3 nm. Pre-treatment with P-AuNPs (1, 10 mg/kg, i.p.) before CYP (150 mg/kg, i.p.) challenge suggested its uroprotective properties. P-AuNPs significantly reversed all pain-like behaviours and toxicities produced by CYP resulting in a decreased aspartate aminotransferase, alanine aminotransferase, C-reactive protein, and creatinine level. P-AuNPs increased anti-oxidant system by increasing the level of reduced glutathione, glutathione-S-transferase, catalase and superoxide dismutase, and reduced nitric oxide production in bladder tissue. Additionally, it attenuated hypokalaemia and hyponatremia, along with a decrease in Evans blue content in bladder tissue and peritoneal cavity. CYP-induced bladder tissue damage observed by macroscopic and histological findings were remarkably attenuated by P-AuNPs, along with reduced fibrosis of collagen fibre in bladder smooth muscles shown by Masson's trichrome staining. Additionally, alterations in hematological parameters and clinical scoring were also prevented by P-AuNPs suggesting its uroprotective effect.

Network pharmacology analysis and experimental verification reveal the mechanism of the traditional Chinese medicine YU-Pingfeng San alleviating allergic rhinitis inflammatory responses

YU-Pingfeng San (YPFS) can regulate inflammatory response to alleviate the symptoms of nasal congestion and runny rose in allergic rhinitis (AR). However, the mechanism of action remains unclear. In this study, 30 active ingredients of three effective herbs included in YPFS and 140 AR/YPFS-related genes were identified by database analysis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the targets were mainly enriched in immune inflammatory-related biological processes and pathways. Finally, three hub gene targeting epidermal growth factor receptor (EGFR), mitogen-activated protein kinase 1 (MAPK1), and protein kinase B1 (AKT1) related to YPFS and AR were identified by network pharmacology analysis. YPFS treatment decreased the expression of EGFR, MAPK1, and AKT1 in ovalbumin (OVA)-induced AR mice and impaired the production of inflammatory factors interleukin (IL)-4, IL-5, and IL-13, thus alleviating immunoglobulin E (IgE) production and the symptoms of scratching nose in AR. Through molecular docking analysis, we found that the active ingredients decursin, anomalin, and wogonin of YPFS could bind to EGFR, MAPK1, and AKT1 proteins. Moreover, decursin treatment impaired the expression of IL-4 and IL-5 in human PBMCs. These results suggested that YPFS could alleviate the AR inflammatory responses by targeting EGFR, MAPK1, and AKT1, showing the mechanism of action of YPFS in AR treatment.

Coagulansin-A improves spatial memory in 5xFAD Tg mice by targeting Nrf-2/NF-κB and Bcl-2 pathway

The present study was designed to investigate the underlying molecular signaling of Coagulansin-A (Coag-A) as a therapeutic agent against Alzheimer's disease (AD). Preliminarily, it exhibited a neuroprotective effect against H2O2-induced oxidative stress in HT-22 cells. The in vivo studies were performed by administering Coag-A (0.1, 1, and 10 mg/kg) intraperitoneally to 5xFAD transgenic (Tg) mouse model. Coag-A (10 mg/kg) significantly attenuated the cognitive decline compared to Tg mice group in the shallow water maze (SWM) and Y-maze test paradigms. The anti-aggregation potential of Coag-A was determined by performing Fourier transform-infrared (FT-IR) spectroscopy and differential scanning calorimeter (DSC) analysis in the prefrontal cortex (PFC) and hippocampal (HC) regions of mice brain. The FT-IR spectra demonstrated the inhibition of amyloid beta (Aβ) through a decrease in β-sheet aggregation, along with the inhibition of changes in the lipids, proteins, and phospholipids. The DSC analysis displayed a low-temperature exotherm associated with the reversible process of aggregation of soluble protein fractions prior to denaturation. Furthermore, Coag-A treatment displayed a regular density of granule cells in H&E stained sections, along with a reduced amyloid load and PAS-positive granules in all the regions of interest in mice brain. The real-time polymerase chain reaction (q-PCR), western blot and immunohistochemical (IHC) analysis demonstrated antioxidant, anti-inflammatory, and anti-apoptotic effect of Coag-A by enhancing the expression of nuclear factor erythroid-2-related factor (Nrf-2) and reducing nuclear factor kappa B (NF-κB) and Bax protein expression. In addition, Coag-A significantly increased the antioxidant enzymes and proteins level, along with a reduced pro-inflammatory cytokines production.

Pharmacological mechanism of xanthoangelol underlying Nrf-2/TRPV1 and anti-apoptotic pathway against scopolamine-induced amnesia in mice

Alzheimer's disease (AD) is a well-known type of age-related dementia. The present study was conducted to investigate the effect of xanthoangelol against memory deficit and neurodegeneration associated with AD. Preliminarily, xanthoangelol produced neuroprotective effect against H₂O₂-induced HT-22 cells. Furthermore, effect of xanthoangelol against scopolamine-induced amnesia in mice was determined by intraperitoneally (i.p.) administering xanthoangelol (1, 10 and 20 mg/kg), 30 min prior to induction. Mice were administered scopolamine at a concentration of 1 mg/kg; i.p. for the induction of amnesia associated with AD. Xanthoangelol dose dependently reduced the symptoms of Alzheimer's disease as observed by the results obtained from the behavioral analysis performed using Morris water maze and Y-maze test. The immunohistochemical analysis suggested that xanthoangelol significantly improved Keap-1/Nrf-2 signaling pathway. It greatly reduced the effects of oxidative stress and showed improvement in the anti-oxidant enzyme such as GSH, GST, SOD and catalase. Additionally, xanthoangelol decreased the expression of transient receptor potential vanilloid 1 (TRPV-1), a nonselective cation channel, involved in synaptic plasticity and memory. It activated the anti-oxidants and attenuated the apoptotic (Bax/Bcl-2) pathway. Xanthoangelol also significantly attenuated the scopolamine-induced neuroinflammation by the inhibition of interleukin-1 beta (IL-1β), and tumor necrosis factor-α (TNF-α) levels. The histological analysis, showed a significant reduction in amyloid plaques by xanthoangelol. Therefore, the present study indicated that xanthoangelol has the ability to ameliorate the AD symptoms by attenuating neuroinflammation and neurodegeneration induced by scopolamine.

Magnolol prevented brain injury through the modulation of Nrf2-dependent oxidative stress and apoptosis in PLP-induced mouse model of multiple sclerosis

Multiple sclerosis (MS) is an immune-mediated chronic inflammatory demyelinating disease of the central nervous system (CNS). The aim of the current study was to investigate the effects of magnolol in an experimental autoimmune encephalomyelitis (EAE) model of MS in female mice. Magnolol (0.1, 1, and 10 mg/kg) was administered once daily for 21 days after immunization of mice. Magnolol post-immunization treatment significantly reversed clinical scoring, EAE-associated pain parameters, and motor dysfunction in a dose-dependent manner. Magnolol treatment significantly inhibited oxidative stress by reducing malondialdehyde (MDA), nitric oxide (NO) production, and myeloperoxidase (MPO) activity while enhancing the level of antioxidants such as reduced glutathione (GSH), glutathione-S-transferase (GST), catalase, and superoxide dismutase (SOD) in the brain and spinal cord. It reduced cytokine levels in the brain and spinal cord. It suppressed CD8+ T cells frequency in the spleen tissue. Magnolol remarkably reversed the EAE-associated histopathology of the brain and spinal cord tissue. Magnolol significantly intensifies the antioxidant defense system by enhancing the expression level of nuclear factor erythroid 2-related factor (Nrf2) while decreasing the expression of inducible nitric oxide synthase (iNOS) and cleaved-caspase-3 in the brain. Molecular docking results showed that magnolol possesses a better binding affinity for Nrf2, iNOS, and caspase-3 proteins. Taken together, the present study demonstrated that magnolol has significant neuroprotective properties in EAE via inhibition of oxidative stress.

A REVIEW ON ANOMALIN: A NATURAL BIOACTIVE PYRANOCOUMARIN FROM THE PAST TO THE FUTURE

Anomalin is a seselin-type pyranocoumarin isolated for the first time from Angelica anomala Avé-Lal, but is also found in several other plant species, especially in Apiaceae. This lipophilic molecule possesses pharmacologically beneficial activities for human health. The major scientific databases Scopus, Web of Science, Google Scholar, and PubMed up to the end of 2021 and the combining terms anomalin, praeruptorin, isolation, structure elucidation, and biological activity were used in the research of this review. This review focuses on the sources, structural properties, and biological functions of anomalin and provides future trends in the investigation of anomalin, particularly in therapies for many common diseases such as anti-inflammatory and neurodegenerative illnesses. As a potential bioactive molecule, prospective studies on anomalin should be done through supported clinical trials. At the end, this review confirms the significant pharmacological potential of anomalin.

Cassia artemisiodes attenuates nociceptive and diabetes-induced neuropathic pain modalities apropos antioxidant and anti-inflammatory mechanisms

Cassia plants have a considerable position in conventional systems of medicine. The possible anti-nociceptive, anti-inflammatory, and anti-neuropathic properties of Cassia artemisiodes (CAD) extract were tested using the standard animal models. In this study, in vitro antioxidant, cyclooxygenase (COX-1 and 2), and 5-lipoxygenase (5-LOX) inhibitory assays were performed. The anti-inflammatory activity was evaluated using carrageenan, histamine, and serotonin-induced paw edema models. Antipyretic activity, thermally and chemically-induced nociception, and naloxone antagonistic activities were carried out. The CAD extract was tested for anti-neuropathic activity in the streptozotocin-induced diabetic neuropathy model. Suppressing the effect of CAD extract on the mRNA level of inducible nitric oxide synthase (iNOS), COX-2, and pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) was determined by performing RT-PCR. The CAD extract inhibited COX-2 and 5-LOX enzymes, paw inflammation, and reduced nociceptive behaviors. The mRNA gene expression of iNOS, COX-2, and inflammatory cytokines was reduced significantly with increased DPPH scavenging activity. The extract significantly reduced the diabetes-induced neuropathic pain. In a nutshell, these results recommended that the CAD extract has anti-nociceptive and anti-neuropathic activities due to inhibition of inflammatory and oxidative signaling.

Possible cytoprotective mechanisms of oxytocin against 5-fluorouracil-induced gastrointestinal mucositis

Gastrointestinal mucositis is a common and dose-limiting side effect characterized by ulcerative lesions in the mucosa of the digestive tract in patients receiving anticancer drugs such as 5-fluorouracil (5-FU), a potent antineoplastic drug. Several protocols have reported the efficacy of therapeutic interventions to prevent this side effect, although complete success has not yet been achieved and mucositis remains one of the most serious complications associated with 5-FU therapy. Oxytocin, a well-known antistress agent, has been reported to have comparable effects to ranitidine. Previous studies have shown that oxytocin inhibits gastric acid secretion and the expression of proinflammatory cytokines in rats. If oxytocin can reduce stress-induced ulcers via antioxidant, antiapoptotic, and anti-inflammatory pathways, then it may have a dose-dependent effect on gastrointestinal mucositis caused by 5-FU.

The Effects of Nuclear Factor Erythroid 2 (NFE2)-Related Factor 2 (Nrf2) Activation in Preclinical Models of Peripheral Neuropathic Pain

Oxidative stress, resulting from an imbalance between the formation of damaging free radicals and availability of protective antioxidants, can contribute to peripheral neuropathic pain conditions. Reactive oxygen and nitrogen species, as well as products of the mitochondrial metabolism such as superoxide anions, hydrogen peroxide, and hydroxyl radicals, are common free radicals. Nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2) is a transcription factor encoded by the NFE2L2 gene and is a member of the cap 'n' collar subfamily of basic region leucine zipper transcription factors. Under normal physiological conditions, Nrf2 remains bound to Kelch-like ECH-associated protein 1 in the cytoplasm that ultimately leads to proteasomal degradation. During peripheral neuropathy, Nrf2 can translocate to the nucleus, where it heterodimerizes with muscle aponeurosis fibromatosis proteins and binds to antioxidant response elements (AREs). It is becoming increasingly clear that the Nrf2 interaction with ARE leads to the transcription of several antioxidative enzymes that can ameliorate neuropathy and neuropathic pain in rodent models. Current evidence indicates that the antinociceptive effects of Nrf2 occur via reducing oxidative stress, neuroinflammation, and mitochondrial dysfunction. Here, we will summarize the preclinical evidence supporting the role of Nrf2 signaling pathways and Nrf2 inducers in alleviating peripheral neuropathic pain.

Anti-neuropathic pain activity of a cationic palladium (II) dithiocarbamate by suppressing the inflammatory mediators in paclitaxel-induced neuropathic pain model

BACKGROUND

Neuropathic pain is a chronic pain state that negatively impacts the quality of life. Currently, available therapies for the treatment of neuropathic pain often lack efficacy and tolerability. Therefore, the search for novel drugs is crucial to obtain treatments that effectively suppress neuropathic pain.

OBJECTIVES

The present study was undertaken to investigate the antinociceptive properties of (1,4-bis-(diphenylphosphino) butane) palladium (II) chloride monohydrate (Compound 1) in a paclitaxel (PTX)-induced neuropathic pain model.

METHODS

Initially, behavioral tests such as mechanical and cold allodynia as well as thermal and tail immersion hyperalgesia were performed to investigate the antinociceptive potential of Compound 1 (5 and 10 mg/kg, b.w). RT-PCR was performed to determine the effect of Compound 1 on the mRNA expression level of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and proinflammatory cytokines such as tumor necrosis factor-alpha (TNF)-α, interleukin (IL)-1β, and IL-6. In addition, antioxidant protein, nitric oxide (NO), and malondialdehyde (MDA) levels were also determined.

RESULTS

The results demonstrated that once-daily dosing of Compound 1 significantly suppressed the PTX-induced behavioral pain responses dose-dependently. The mRNA gene expressions of iNOS, COX-2, and inflammatory cytokines were markedly reduced by Compound 1. Furthermore, it enhanced the level of antioxidant enzymes and lowered the level of MDA and NO production.

CONCLUSION

These findings suggest that the antinociceptive potential of Compound 1 in the PTX-induced neuropathic pain model is via suppression of oxidative stress and inflammation. Thus, Compound 1 might be a potential candidate for the therapeutic management of PTX induced neuropathic pain.

Amelioration of Neuropathic Pain and Attenuation of Neuroinflammation Responses by Tetrahydropalmatine Through the p38MAPK/NF-κB/iNOS Signaling Pathways in Animal and Cellular Models

Neuropathic pain (NP) treatment remains a challenge because the pathomechanism is not yet fully understood. Because of low treatment efficacy, there is an important unmet need in neuropathic pain patients, and the development of a more effective pharmacotherapy is urgently required. Neuroinflammation induced by oxidative stress-mediated activation of nuclear factor-kappa B (NF-κB) plays an important role in NP. In this study, we aimed to investigate the protective properties of tetrahydropalmatine (THP) on a spared nerve injury (SNI) model of neuropathic pain in mice in in vivo and also in in vitro experiments. THP decreased mechanical hyperalgesia and cold allodynia compared with the SNI group. A microarray was applied to analyze differentially expressed of mRNA among different groups, and THP noticeably changed the expression of MAPK-related proteins compared with the SNI groups. H&E staining showed that the THP changed the inflammation after the spared nerve injury, with decreased NO expression in the THP group as compared to the SNI group. In addition, SNI-induced pain was reversed by intraperitoneal administration of THP, and further results indicated that THP suppressed inducible nitric oxide synthase (iNOS, pro-nociceptive mediators), phosphorylated MAPKs, and p65 in the dorsal root ganglions and sciatic nerve, while the serum levels of the pro-inflammatory cytokines IL-1β were significantly higher in the SNI group as compared to the THP group. To identify the molecular mechanism of the antineuropathic activity of THP, sodium nitroprusside (SNP)-induced neuro-2a (N2a) cells, LPS-induced BV2 cells, and LTA-induced astrocytes were further investigated in signaling pathways. In vitro experiments indicated that THP suppressed the expression of IL-1β, iNOS, phosphorylated MAPKs, and p65, which were assayed using western blotting, and immunofluorescence.

The role of dorsal root ganglia alpha-7 nicotinic acetylcholine receptor in complete Freund's adjuvant-induced chronic inflammatory pain

BACKGROUND

Alpha-7 nicotinic acetylcholine receptor (α7 nAChR) was reported to have a critical role in the regulation of pain sensitivity and neuroinflammation. However, the expression level of α7 nAChR in dorsal root ganglion (DRG) and the underlying neuroinflammatory mechanisms associated with hyperalgesia are still unknown.

METHODS

In the present study, the expression and mechanism of α7 nAChR in chronic inflammatory pain was investigated using a complete Freund's adjuvant (CFA)-induced chronic inflammatory pain model. Subsequently, a series of assays including immunohistochemistry, western blotting, and quantitative real-time polymerase chain reaction (qRT-PCR) were performed.

RESULTS

α7 nAChR was mostly colocalized with NeuN in DRG and upregulated after CFA injection. Microinjection of α7 nAChR siRNA into ipsilateral L4/5 DRGs aggravated the CFA-induced pain hypersensitivity. Intrathecal α7 nAChR agonist GTS-21 attenuated the development of CFA-induced mechanical and temperature-related pain hypersensitivities. In neuronal the SH-SY5Y cell line, the knockdown of α7 nAChRs triggered the upregulation of TRAF6 and NF-κB under CFA-induced inflammatory conditions, while agitation of α7 nAChR suppressed the TRAF6/NF-κB activation. α7 nAChR siRNA also exacerbated the secretion of pro-inflammatory mediators from LPS-induced SH-SY5Y cells. Conversely, α7 nAChR-specific agonist GTS-21 diminished the release of interleukin-1beta (IL-1β), IL-6, IL-8, and tumor necrosis factor-α (TNFα) in SH-SY5Y cells under inflammatory conditions. Mechanistically, the modulation of pain sensitivity and neuroinflammatory action of α7 nAChR may be mediated by the TRAF6/NF-κB signaling pathway.

CONCLUSIONS

The findings of this study suggest that α7 nAChR may be potentially utilized as a therapeutic target for therapeutics of chronic inflammatory pain.

Alleviation of Memory Deficit by Bergenin via the Regulation of Reelin and Nrf-2/NF-κB Pathway in Transgenic Mouse Model

The present study aims to determine the neuroprotective effect of Bergenin against spatial memory deficit associated with neurodegeneration. Preliminarily, the protective effect of Bergenin was observed against H2O2-induced oxidative stress in HT-22 and PC-12 cells. Further studies were performed in 5xFAD Tg mouse model by administering Bergenin (1, 30 and 60 mg/kg; orally), whereas Bergenin (60 mg/kg) significantly attenuated the memory deficit observed in the Y-maze and Morris water maze (MWM) test. Fourier transform-infrared (FT-IR) spectroscopy displayed restoration of lipids, proteins and their derivatives compared to the 5xFAD Tg mice group. The differential scanning calorimeter (DSC) suggested an absence of amyloid beta (Aβ) aggregation in Bergenin-treated mice. The immunohistochemistry (IHC) analysis suggested the neuroprotective effect of Bergenin by increasing Reelin signaling (Reelin/Dab-1) and attenuated Aβ (1-42) aggregation in hippocampal regions of mouse brains. Furthermore, IHC and western blot results suggested antioxidant (Keap-1/Nrf-2/HO-1), anti-inflammatory (TLR-4/NF-kB) and anti-apoptotic (Bcl-2/Bax/Caspase-3) effect of Bergenin. Moreover, a decrease in Annexin V/PI-stained hippocampal cells suggested its effect against neurodegeneration. The histopathological changes were reversed significantly by Bergenin. In addition, a remarkable increase in antioxidant level with suppression of pro-inflammatory cytokines, oxidative stress and nitric oxide production were observed in specific regions of the mouse brains.

Attenuation of nociceptive and paclitaxel-induced neuropathic pain by targeting inflammatory, CGRP and substance P signaling using 3-Hydroxyflavone

Paclitaxel is an anti-microtubule agent, most widely used chemotherapeutic agent for the treatment of malignant solid tumors. However, it is associated with some severe side effects including painful neurotoxicity with reporting of neuropathic pain and sensory abnormalities by patients during and after paclitaxel therapy. Peripheral neuropathy was induced by the administration of paclitaxel (4 mg/kg on days 1, 3, 5, and 7). In this study, the anti-nociceptive and anti-inflammatory propensity of 3-Hydroxyflavone (3HF) in mice and the preventive effect of 3HF against paclitaxel-induced peripheral neuropathy in Sprague Dawley (SD) rats were investigated. Moreover, tactile and cold allodynia, thermal and tail immersion hyperalgesia, and effects on motor-coordination were also evaluated. Furthermore, the expression of proinflammatory cytokines i.e. Calcitonin gene-related peptide (CGRP), and Substance P from the spinal cord was examined through RT-PCR. Additionally, a computational structural biology approach was applied to search the potential therapeutic targets and to predict the binding mechanism of 3HF. Treatment of 3HF alleviated the nociceptive pain, paw edema, development of tactile and cold allodynia, and hyperalgesia. Similarly, treatment with 3HF suppressed the paclitaxel-induced increase in mRNA expression of several inflammatory cytokines including tumor necrosis factor -α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6), CGRP, and Substance P. However, the daily treatment of 3HF did not affect the motor behaviors of rats. The inhibitory mechanism of 3HF in neuropathic pain is predicted with extensive computational bioinformatics approach which indicates that the 3HF effectively interacts with the binding domains of Nuclear factor-kappa B (NF-κB), CGRP receptor and the receptor of Substance P to exert its inhibitory activities. However, the computationally predicted binding affinities revealed that the potential of binding of the compound with Substance P receptor (Neurokinin 1 receptor) is higher than the other receptors; there NK1R could be the most possible binding target of 3HF. These findings indicate that 3HF has anti-nociceptive, anti-inflammatory, and anti-neuropathic pain effects against paclitaxel-induced neuropathic pain.

7β-(3-Ethyl-cis-crotonoyloxy)-1α-(2-methylbutyryloxy)-3,14-dehydro-Z Notonipetranone Attenuates Neuropathic Pain by Suppressing Oxidative Stress, Inflammatory and Pro-Apoptotic Protein Expressions

7β-(3-Ethyl-cis-crotonoyloxy)-1α-(2-methylbutyryloxy)-3,14-dehydro-Z-notonipetranone (ECN), a sesquiterpenoid obtained from a natural source has proved to be effective in minimizing various side effects associated with opioids and nonsteroidal anti-inflammatory drugs. The current study focused on investigating the effects of ECN on neuropathic pain induced by partial sciatic nerve ligation (PSNL) by mainly focusing on oxidative stress, inflammatory and apoptotic proteins expression in mice. ECN (1 and 10 mg/kg, i.p.), was administered once daily for 11 days, starting from the third day after surgery. ECN post-treatment was found to reduce hyperalgesia and allodynia in a dose-dependent manner. ECN remarkably reversed the histopathological abnormalities associated with oxidative stress, apoptosis and inflammation. Furthermore, ECN prevented the suppression of antioxidants (glutathione, glutathione-S-transferase, catalase, superoxide dismutase, NF-E2-related factor-2 (Nrf2), hemeoxygenase-1 and NAD(P)H: quinone oxidoreductase) by PSNL. Moreover, pro-inflammatory cytokines (tumor necrotic factor-alpha, interleukin 1 beta, interleukin 6, cyclooxygenase-2 and inducible nitric oxide synthase) expression was reduced by ECN administration. Treatment with ECN was successful in reducing the caspase-3 level consistent with the observed modulation of pro-apoptotic proteins. Additionally, ECN showed a protective effect on the lipid content of myelin sheath as evident from FTIR spectroscopy which showed the shift of lipid component bands to higher values. Thus, the anti-neuropathic potential of ECN might be due to the inhibition of oxidative stress, inflammatory mediators and pro-apoptotic proteins.

Matrine alleviates neurobehavioral alterations via modulation of JNK-mediated caspase-3 and BDNF/VEGF signaling in a mouse model of burn injury

RATIONALE

The c-Jun N-terminal kinase (JNK) pathway and neurotrophic factor dysregulation play a critical role in the pathogenesis of neurobehavioral disorders (anxiety and depression). Targeting the JNK pathway and BDNF/VEGF signaling may signify a new avenue for the treatment of neurobehavioral disorders.

OBJECTIVES

The present study investigated the effect of matrine (Mat) against anxiety- and depressive-like emotional status in an acute mouse model of burn injury and explores its underlying mechanism.

METHODS

In the mouse model of thermal injury, anxiety- and depression-related behaviors were evaluated using the elevated plus-maze test, the light-dark box test, the open-field test, the forced swimming test, and the tail suspension test. The JNK/caspase-3 and BDNF/VEGF proteins were determined by immunohistochemistry. Additionally, proinflammatory cytokine, antioxidant, nitric oxide, and corticosterone levels were also measured.

RESULTS

The results showed that treatment with Mat significantly improves anxiety- and depressive-like behaviors. It remarkably reduced the levels of proinflammatory cytokines, malondialdehyde, and nitric oxide in the hippocampus and prefrontal cortex of a mouse brain. It considerably improved burn-induced alteration in the antioxidant status, corticosterone, and BDNF/VEGF. It also inhibited burn-induced apoptotic signaling by downregulating the expression of JNK/caspase-3. Similarly, it prevented DNA damage and histopathological changes in the dentate gyrus of the hippocampus. Furthermore, molecular docking results showed that Mat possess better binding affinity for JNK/caspase-3 and BDNF/VEGF proteins.

CONCLUSIONS

These findings provide convincing evidence that Mat improves anxiety- and depressive-like emotional status through modulation of JNK-mediated inflammatory, oxidative stress, apoptotic, and BDNF/VEGF signaling in an acute mouse model of burn injury.

Coumarins as Modulators of the Keap1/Nrf2/ARE Signaling Pathway

The Keap1/Nrf2/ARE system is a central defensive mechanism against oxidative stress which plays a key role in the pathogenesis and progression of many diseases. Nrf2 is a redox-sensitive transcription factor controlling a variety of downstream antioxidant and cytodefensive genes. Nrf2 has a powerful anti-inflammatory activity mediated via modulating NF-κB. Therefore, pharmacological activation of Nrf2 is a promising therapeutic strategy for the treatment/prevention of several diseases that are underlined by both oxidative stress and inflammation. Coumarins are natural products with promising pharmacological activities, including antioxidant, anticancer, antimicrobial, and anti-inflammatory efficacies. Coumarins are found in many plants, fungi, and bacteria and have been widely used as complementary and alternative medicines. Some coumarins have shown an ability to activate Nrf2 signaling in different cells and animal models. The present review compiles the research findings of seventeen coumarin derivatives of plant origin (imperatorin, visnagin, urolithin B, urolithin A, scopoletin, esculin, esculetin, umbelliferone, fraxetin, fraxin, daphnetin, anomalin, wedelolactone, glycycoumarin, osthole, hydrangenol, and isoimperatorin) as antioxidant and anti-inflammatory agents, emphasizing the role of Nrf2 activation in their pharmacological activities. Additionally, molecular docking simulations were utilized to investigate the potential binding mode of these coumarins with Keap1 as a strategy to disrupt Keap1/Nrf2 protein-protein interaction and activate Nrf2 signaling.

Continentalic acid exhibited nephroprotective activity against the LPS and E. coli-induced kidney injury through inhibition of the oxidative stress and inflammation

The present study investigated the effect of the continentalic acid (CNT) isolated from the Aralia Continentalis against the LPS and E. coli-induced nephrotoxicity. The LPS and E. coli administration markedly altered the behavioral parameters including spontaneous pain, tail suspension and survival rate. However, the treatment with CNT dose dependently improved the behavioral parameters. The CNT treatment significantly improved the renal functions test (RFTs) and hematological parameters following LPS and E. coli-induced kidney injury. Furthermore, the LPS and E. coli administration markedly compromised the anti-oxidant enzymes and enhanced the oxidative stress markers. However, the CNT treatment markedly enhanced the anti-oxidants enzymes such as GSH, GST, Catalase and SOD, while attenuated the oxidative stress markers such as MDA and POD. The MPO enzyme is widely used marker for the neutrophilic infiltration, the LPS and E. coli administration markedly increased the MPO activity. However, the CNT treatment markedly attenuated the MPO activity in both LPS and E. coli-induced kidney injury. Furthermore, the CNT treatment markedly attenuated the NO production compared to the LPS and E. coli-induced kidney injury group. Additionally, the CNT treatment improved the histological parameters markedly (H and E, PAS and Masson's trichome staining) and protect the kidney from the inflammatory insult of the LPS and E. coli evidently. The comet assay revealed marked DNA damage, however, the CNT treatment markedly prevented the LPS and E. coli-induced kidney damage. The CNT treatment markedly enhanced the expression of Nrf2, while attenuated the iNOS expression in both models of kidney injury.

Dexmedetomidine attenuates P2X4 and NLRP3 expression in the spine of rats with diabetic neuropathic pain

Purpose:

To evaluate the effects of Dexmedetomidine (Dex) on spinal pathology and inflammatory factor in a rat model of Diabetic neuropathic pain (DNP).

Methods:

The rats were divided into 3 groups (eight in each group): normal group (N group), diabetic neuropathic pain model group (DNP group), and DNP model with dexmedetomidine (Dex group). The rat model of diabetes was established with intraperitoneal streptozotocin (STZ) injections. Nerve cell ultrastructure was evaluated with transmission electron microscopy (TEM). The mechanical withdrawal threshold (MWT) and motor nerve conduction velocity (MNCV) tests documented that DNP rat model was characterized by a decreased pain threshold and nerve conduction velocity.

Results:

Dex restored the phenotype of neurocytes, reduced the extent of demyelination and improved MWT and MNCV of DNP-treated rats (P=0.01, P=0.038, respectively). The expression of three pain-and inflammation-associated factors (P2X4, NLRP3, and IL-IP) was significantly upregulated at the protein level in DNP rats, and this change was reversed by Dex administration (P=0.0022, P=0.0092, P=0.0028, respectively).

Conclusion:

The P2X4/NLRP3 signaling pathway is implicated in the development and presence of DNP in vivo, and Dex protects from this disorder.

Suppression of TRPV1 and P2Y nociceptors by honokiol isolated from Magnolia officinalis in 3rd degree burn mice by inhibiting inflammatory mediators

Burn pain is one of the worst imaginable pain, associated with considerable morbidity and mortality worldwide. The management of pain made significant progress; however, more research is needed for burn pain. In the present study, the antinociceptive effect of honokiol extracted from Magnolia officinalis was assessed for 3 consecutive days. The third-degree burns were induced by the hot water method. The honokiol both by intraperitoneal (i.p) and intra plantar (i.pl) route and in combination with tramadol (i.p) was found to be effective in significantly reducing the mechanical allodynia, hyperalgesia, thermal hyperalgesia and paw edema. Honokiol also succeeded in reducing weight loss and spontaneous pain behavior in mice. Honokiol treatment both i.p and ipl decrease significantly the loss of total protein (3.3 and 3.4 g/dl of total protein) and albumin (2.2 and 2.6 g/dl of total albumin) respectively. It also significantly recovers the normal balance of blood electrolytes and normalizes blood profile. Effect of honokiol on cytokines and mRNA expression levels of TRPV1 and P2Y were also assessed. Honokiol significantly decreases the expression of TNF-α, IL-1β and IL-6 and decreases expression level of TRPV1 and P2Y. Additionally, TRPV1 and P2Y proteins expression levels were also assessed by Western blot in paw skin tissue, sciatic nerve and spinal cord which were remarkably down-regulated by honokiol. Histological analysis of vehicle control and drug-treated paws were also performed through hematoxylin and eosin (H&E) staining which exhibited that honokiol significantly reduced the dermal layers distortion and inflammation associated with the burn. The antioxidant enzymes and nitric oxide (NO) were also determined through ELISA. Honokiol treatment also potentiates the expression of reduced glutathione and glutathione S-transferase, and catalase levels and reduced significantly the nitric oxide (NO) as compared to the burn-induced group. It can be concluded on the base of the results that honokiol has a significant analgesic activity through its action on cytokines and by downregulating TRPV1 and P2Y receptors. It also has a protective role against burn damage by upregulation of antioxidants.

N-Pyrazoloyl and N-thiopheneacetyl hydrazone of isatin exhibited potent anti-inflammatory and anti-nociceptive properties through suppression of NF-κB, MAPK and oxidative stress signaling in animal models of inflammation

BACKGROUND

Hydrazide derivatives constitute an important class of compounds for new drug development as they are reported to possess good anti-inflammatory and analgesic activity. The present study was aimed to investigate the role of newly synthesized hydrazide derivatives N-pyrazoloyl hydrazone of isatin (PHI) and N-thiopheneacetyl hydrazone of isatin (THI) in acute and chronic inflammatory pain models induced by carrageenan and complete Freud's adjuvant (CFA).

MATERIALS

PHI and THI (0.1, 1 and 10 mg/kg) pretreatments were provided intraperitoneally to male BALB/c mice prior to inflammatory inducers. Behavioral responses to inflammation and pain were evaluated by assessment of paw edema, mechanical allodynia, mechanical and thermal hyperalgesia. Cytokines production and NF-κB levels were evaluated by ELISA. Western blot analysis was performed for the detection of IκBα, p38, JNK and ERK. Hematoxylin and eosin (H&E) staining and radiographic analysis were performed to evaluate the effect of PHI and THI treatment on bone and soft tissues. Oxidative stress was determined by reduced glutathione, glutathione-S-transferase and catalase assays. Evans blue dye was used to monitor vascular protein leakage.

RESULT

PHI and THI dose dependently (0.1, 1 and 10 mg/kg) reduced inflammation and pain in mice, however, the dose of 10 mg/kg exhibited significant activity. The anti-inflammatory and analgesic effects were attributed to suppression of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) production levels. PHI and THI significantly blocked CFA-induced activation of NF-κB and MAPK signaling pathways. Oxidative stress and plasma nitrite levels were reduced remarkably. The PHI and THI (10 mg/kg) treatment did not exhibit any apparent toxicity on the liver, kidney, muscles strength, and motor co-ordination in mice.

CONCLUSION

Both PHI and THI possess significant anti-inflammatory and analgesic activity via inhibition of inflammatory mediators.

Antihyperalgesic Properties of Honokiol in Inflammatory Pain Models by Targeting of NF-κB and Nrf2 Signaling

The present study investigates the possible anti-nociceptive effect of intraperitoneal (i.p.) honokiol: a phenolic compound originally isolated from Magnolia officinalis, in acute and chronic inflammatory pain models. Doses of 0.1, 5, and 10 mg/kg honokiol were administered in carrageenan induced pain and the dose (honokiol 10 mg/kg i.p.) with most significant response among behavioral tests was selected for further experiments. The i.p. administration of honokiol inhibits mechanical hyperalgesia, mechanical allodynia, and thermal hyperalgesia, without causing any apparent toxicity. To elucidate the effect of honokiol on various cytokines and antioxidant enzymes, quantitative real-time-PCR was performed to determine the expression levels of pro-inflammatory cytokines and antioxidant enzymes. It is demonstrated that honokiol significantly reduced the expression levels of tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), and vascular endothelial growth factor (VEGF). Similarly, honokiol was also found to potentiate the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), superoxide dismutase 2 (SOD2), and heme oxygenase-1 (HO-1) levels. Additionally, honokiol significantly reduced plasma nitrite levels as compared to complete Freund's adjuvant (CFA) induced group. X-ray analysis and hematoxylin and eosin (H&E) staining of inflamed and treated paws showed that honokiol reduced the inflammation with significantly less leukocyte infiltration and soft tissue inflammation. In order to explore the possible mechanism of action of honokiol, agonists [piroxicam (5 mg/kg), tramadol (50 mg/kg), and gabapentin (5 mg/kg) i.p.] as well as antagonists [naloxone (4 mg/kg), olanzapine (10 mg/kg), and flumazenil (0.2 mg/kg) i.p.] were used to study involvement of various receptors on the anti-nociceptive effect of honokiol. The potential side effects of honokiol on muscle activity were assessed. An adverse effect testing of honokiol by liver and renal functions were also carried out. The effect of oral honokiol was also assessed on gastrointestinal (GIT) mucosa. Our results demonstrate that honokiol has a significant anti-nociceptive activity through inhibition of anti-inflammatory mediators.

Coumarins as potential antidiabetic agents

OBJECTIVES

Even with great advances in modern medicine and therapeutic agent development, the search for effective antidiabetic drugs remains challenging. Coumarins are secondary metabolites found widely in nature plants and used mainly in anticoagulation and antithrombotic therapy. Over the past two decades, however, there has been an increasing body of literatures related to the effects of coumarins and their derivatives on diabetes and its complications. This review aimed to focus on research findings concerning the effects of coumarins against diabetes and its complications using in-vitro and in-vivo animal models, and also to discuss cellular and molecular mechanisms underlying these effects.

KEY FINDINGS

The search for new coumarins against diabetes and it complications, either isolated from traditional medicine or chemically synthesized, has been constantly expanding. The cellular and molecular mechanisms involved include protecting pancreatic beta cells from damage, improving abnormal insulin signalling, reducing oxidative stress/inflammation, activating AMP-activated protein kinase (AMPK), inhibiting α-glucosidases and ameliorating diabetic complications.

CONCLUSIONS

The effects and mechanisms of coumarins and their derivatives upon diabetes and its complications are discussed in current review. Further investigations remain to be carried out to develop a promising antidiabetic agent based on coumarin cores.