Spinal apolipoprotein E is involved in inflammatory pain via regulating lipid metabolism and glial activation in the spinal dorsal horn

INTRODUCTION

Inflammation and nerve injury promote astrocyte activation, which regulates the development and resolution of pain, in the spinal dorsal horn. APOE regulates lipid metabolism and is predominantly expressed in the astrocytes. However, the effect of astrocytic APOE and lipid metabolism on spinal cellular function is unclear. This study aimed to investigate the effect of spinal Apoe on spinal cellular functions using the complete Freund's adjuvant (CFA)-induced inflammatory pain mouse model.

METHODS

After intraplantar injection of CFA, we assessed pain behaviors in C57BL6 and Apoe knockout (Apoe-/-) mice using von Frey and Hargreaves' tests and analyzed dorsal horn samples (L4-5) using western blotting, immunofluorescence, quantitative real-time polymerase chain reaction, and RNA sequencing.

RESULTS

The Apoe levels were markedly upregulated at 2 h and on days 1 and 3 post-CFA treatment. Apoe was exclusively expressed in the astrocytes. Apoe-/- mice exhibited decreased pain on day 1, but not at 2 h, post-CFA treatment. Apoe-/- mice also showed decreased spinal neuron excitability and paw edema on day 1 post-CFA treatment. Global transcriptomic analysis of the dorsal horn on day 1 post-CFA treatment revealed that the differentially expressed mRNAs in Apoe-/- mice were associated with lipid metabolism and the immune system. Astrocyte activation was impaired in Apoe-/- mice on day 1 post-CFA treatment. The intrathecal injection of Apoe antisense oligonucleotide mitigated CFA-induced pain hypersensitivity.

CONCLUSIONS

Apoe deficiency altered lipid metabolism in astrocytes, exerting regulatory effects on immune response, astrocyte activation, and neuronal activity and consequently disrupting the maintenance of inflammatory pain after peripheral inflammation. Targeting APOE is a potential anti-nociception and anti-inflammatory strategy.

Vetiver aerial parts and roots ameliorate rheumatoid arthritis in complete Freund's adjuvant rat model, a phytochemical profiling and mechanistic study

ETHNOPHARMACOLOGICAL RELEVANCE

Vetiver (Chrysopogon zizanioides) is indigenous to India where it is traditionally used to relief rheumatisms, lumbagos and sprains. Vetiver anti-inflammatory activity has not been previously investigated, and its specific interactions with body inflammation cascade remain largely unknown.

AIM OF THE STUDY

The present work was performed to validate the ethnobotanical use of the plant and compare the anti-inflammatory activities of the ethanolic extracts of the most traditionally used part (aerial part) to that of the root. Furthermore, we attempt to reveal the molecular mechanism of this anti-inflammatory activity in correlation to the chemical composition of C. zizanioides aerial (CA) and root parts (CR).

MATERIALS AND METHODS

Ultraperformance liquid chromatography coupled to high resolution mass spectrometry (UHPLC/HRMS) was used for comprehensive analysis of both CA and CR. The anti-inflammatory effect of both extracts was evaluated in complete Freund's adjuvant (CFA)-induced RA model in Wistar rats.

RESULTS

Phenolic metabolites were predominant in CA and 42 were identified for the first time, while only 13 were identified in CR. Meanwhile, triterpenes and sesquiterpenes were confined to the root extract. In CFA arthritis model, CA showed better anti-inflammatory activity than CR marked by an increase in serum level of IL-10 with simultaneous decrease in pro-inflammatory markers; IL-6, ACPA and TNF-α and was evident in histopathological examination. This anti-inflammatory effect was accompanied by down-regulation of JAK2/STAT3/SOCs3, ERK1/ERK2, TRAF6/c-FOS/NFATC1, TRAF6/NF-κB/NFATC1 and RANKL pathways which were all upregulated after CFA injection. These pathways were modulated to larger extent by CA, except for ERK1/ERK2 which was downregulated more effectively by CR. This differential effect between CA and CR can be explained by the variability in their phytoconstituents profile.

CONCLUSION

In agreement with the ethnobotanical preference, CA extract was more effective than CR extract in reducing the symptoms of RA probably due to its enrichment with flavonoids, lignans, and flavolignans. Both CA and CR reduced the production of inflammatory cytokines through modulating various biological signaling pathways. These findings support the traditional use of vetiver leaves as a remedy for RA and suggest that the use of the whole plant may offer advantage by synergistically affecting more inflammatory pathways.

Efficacy of radial shock wave therapy on rat models of adjuvant arthritis

BACKGROUND

Extracorporeal shock wave therapy (ESWT) is an effective treatment for musculoskeletal pain, tendinopathy, and fasciitis with an anti-inflammatory effect. ESWT can be categorized into two groups: radial pressure wave (RPW) and focused shock wave (FSW). Although there have been several studies on the inflammation and pain-improvement mechanisms of FSW, there are few studies on the pain-improvement mechanisms of RPW. This study aimed to elucidate the efficacy of RPW in a rat model of adjuvant arthritis.

METHODS

Ninety-six rats were randomly categorized into three groups: RPW, control, and sham as follows: (I) RPW group, which received RPW application after complete Freund's adjuvant (CFA) injection; (II) Control group, which received only CFA injection; and (III) Sham group, which received only saline injection. All rats were evaluated at 0, 4, 7, 14, 28, and 56 days post-RPW application based on foot circumference, von Frey test, and immunohistochemistry of nerve fibers for calcitonin gene-related peptide (CGRP) and protein gene product (PGP) 9.5 in plantar skins.

RESULTS

There were no significant differences in foot circumference between the RPW and control groups at any time point. The RPW group showed significant improvements in the von Frey test results on days 7 and 14. The total CGRP-immunoreactive (ir) and PGP9.5-ir nerve fiber lengths in the RPW group decreased on day 0; however, both were increased in the control group. The CGRP-ir and PGP9.5-ir nerve fibers in the RPW group were significantly shorter than those in the control group until day 14 after RPW.

CONCLUSIONS

RPW improved the mechanical hypersensitivity between days 7 and 14 after application. Like FSW, RPW also induced the degeneration of sensory nerve fibers in the skin in the early period after irradiation, and reinnervation occurred between 14 and 28 days. Thus, our results demonstrate one of the pain relief mechanisms after RPW application.

"Cerastes snake venom as a promising approach in the management of complete Freund's adjuvant-induced rheumatoid arthritis in rats: Involvement of RANKL and JAK/STAT pathway"

ETHNOPHARMACOLOGICAL RELEVANCE

Cerastes cerastes is a snake found mainly in the Egyptian desert. Many studies were performed to explain the possible snake venom's pharmacological therapeutic effect in different autoimmune diseases. One of the most common auto-immune diseases is rheumatoid arthritis. Rheumatoid arthritis is characterized by a high release of pro-inflammatory and immune-modulatory cytokines. The reduction of these markers can indicate how effective is the administered drug.

AIM OF THE STUDY

This study aims to explore the potential pharmacological effects of cerastes venom in experimentally-induced RA in rats using Complete Freund's adjuvant - via different mechanisms - by assessing various tissue and serum parameters.

MATERIALS AND METHODS

The rats were assigned to negative control group, cerastes control group, positive control group, dexamethasone-treated group, infliximab-treated group, and cerastes-treated group. The study ended on the 20^th day when serum and tissue samples were prepared for further evaluation of reduced glutathione, malondialdehyde, rheumatoid factor, tumor necrosis factor-α, interleukin-6, and nuclear factor kappa-light-chain-enhancer of activated B cells as well as relative expression of phosphorylated Janus-kinase, phosphorylated signal transducers and activators of transcription, nuclear factor erythroid 2-related factor 2, and receptor activator of nuclear factor Kappa-B ligand. In addition, a histopathological examination of different groups' knees joints, and spleen was done.

RESULTS

The results showed a significant improvement of arthritis induced in the cerastes-treated group in contrast to the positive control group in all assessed parameters. In addition, significant improvement of arthritis was observed in the histopathological examination of different groups' knees joints, and spleen.

CONCLUSION

These results revealed that cerastes snake venom has potent anti-inflammatory and immunomodulatory effects and can be used in the management of arthritis.

Validation of traditional claims of anti-arthritic efficacy of trans-Himalayan snow mountain garlic (Allium ampeloprasum L.) extract using adjuvant-induced arthritis rat model: A comparative evaluation with normal garlic (Allium sativum L.) and dexamethasone

ETHNOPHARMACOLOGICAL RELEVANCE

Snow Mountain Garlic (SMG) (Allium ampeloprasum L.) is a wild trans-Himalayan member of the genus Allium, valued for its anti-inflammatory and anti-arthritic properties in the mountain folk medicinal system (Sowa-Rigpa). Despite its age-old medicinal usage by traditional therapists and the native population for various ailments including rheumatism, there is no scientific validation of its phyto-pharmaceutical merits.

AIM OF THE STUDY

The present pre-clinical study compared the in-vivo anti-arthritic effects of SMG with reported efficacy doses of normal garlic (Allium sativum L.) extract and dexamethasone in a complete Freund's adjuvant (CFA)-induced arthritis rat model.

MATERIALS AND METHODS

The female Wistar rats were immunized by the subplannter injection of CFA into the right hind footpad. Aqueous extracts of SMG and normal garlic were administered orally at a dose of 250 mg/kg and 500 mg/kg for 28 days. Dexamethasone was used as positive control drug. Behavioral parameters including paw markers, arthritis index, joint stiffness, body weight change, etc. were measured. Also, the changes in histopathological indices, hematological profile, inflammatory mediators, and serum cytokines level was determined.

RESULTS

Treatment of rats with SMG extracts significantly (p < 0.001) prevented the reduction in body weight and hematological changes as well as ameliorated clinical symptoms such as arthritic index, joint stiffness, arthritis score, edema, hyperalgesia, and histopathological indices. This was associated with a significant reduction in the serum levels of RF, CRP, anti-CCP, and proinflammatory cytokines exhibiting strong anti-arthritic potential. SMG extracts could also significantly down regulate the NF-κB, COX-2, and iNOS expression in the ankle joint tissues.

CONCLUSIONS

The present study is the first attempt to validate the phyto-pharmaceutical efficacy of this folk garlic variety from the trans-Himalayan region. Overall, SMG extract showed remarkable preventive anti-inflammatory and anti-arthritic activities which were closely comparable to therapeutic effects of dexamethasone and at par or even better than normal garlic w.r.t. several study parameters.

Anti-inflammatory and analgesic effect of Forsythiaside B on complete Freund's adjuvant-induced inflammatory pain in mice

Chronic pain is frequently reported in clinical practice. Therefore, it is important to identify effective therapy to relieve pain. In this work, we selected Forsythoside B (FB), a phenylethanoid glycoside isolated from Forsythia suspensa (Thunb.) Vahl, to evaluate its effect in modulating inflammatory pain induced by complete Freund's adjuvant (CFA) and the involved mechanisms. We discovered that FB could attenuate inflammatory pain triggered by CFA injection and exert anti-anxiety effects. In detail, proinflammatory cytokines, consisting of IL-6 and TNF-α, were decreased after FB administration in the CFA-injected mice. Furthermore, the FB application ameliorated the activation of ionized calcium-binding adaptor molecule 1 (Iba-1) and glial fibrillary acidic protein (GFAP), the microglia and astrocytes markers respectively. Therefore, our findings indicate that FB could be a promising treatment for chronic inflammatory pain.

Exploration of essential oil from Psychotria poeppigiana as an anti-hyperalgesic and anti-acetylcholinesterase agent: Chemical composition, biological activity and molecular docking

ETHNOPHARMACOLOGICAL RELEVANCE

Leaves from Psychotria poeppigiana Müll. Arg. (accepted as Palicourea tomentosa (Aubl.) Borhidi), Rubiaceae, has traditionally been used in medicine for treatments of inflammation and pain; Synonymously, Cephaelis elata for the treatment of dementia; However, few scientific studies have been evidence demonstrating this activity.

AIM OF THE STUDY

The aim of this study was to investigate the chemical composition of P. poeppigiana essential oil obtained from leaves (EOPP) and its antioxidant, anti-inflammatory and acetylcholinesterase (AChE) activities. Molecular docking simulations were carried out with the main constituents.

MATERIALS AND METHODS

EOPP (hydrodistillation) was analysed by gas chromatography-mass spectrometry (GC-MS). The fractionation of EOPP afforded germacrene D and bicyclogermacrene. The antioxidant activity of EOPP was determined by MDA assay. The inflammatory parameters were evaluated using CFA model (with paw edema, mechanical, thermal hyperalgesia, MPO and NAG) in EOPP (30, 100 and 300 mg/kg), germacrene D and bicyclogermacrene (30 mg/kg). The AChE inhibition was evaluated in rat brain structures and molecular docking simulations were carried out using Autodock v.4.3.2.

RESULTS

GC-MS analysis identified 19 compounds, and the major compounds were germacrene D (29.38%) and bicyclogermacrene (25.21%). EOPP exhibited high antioxidant capacity (IC₅₀ = 12.78 ± 1.36 μg/mL). All the tested doses of EOPP and both major constituents significantly inhibited cold and mechanical hyperalgesia and significantly blocked the increase in MPO activity 24 h after the CFA injection. There was significant AChE inhibition by EOPP and germacrene D in the cerebral cortex and hippocampus (>50%). Enzyme-ligand molecular modelling showed that the major constituents of EOPP interacted differently with AChE.

CONCLUSIONS

The chemical compounds of the essential oil from the leaves of P. poeppigiana is based mainly on terpenes, the sesquiterpenes germacrene D (29.38%) and bicyclogermacrene (25.21%) being the major compounds. EOPP presented antioxidant, anti-inflammatory and anti-acetylcholinesterase (AChE) activities. Besides, enzyme-ligand molecular modelling showed the EOPP may act as an anti-hyperalgesic and AChE inhibitory agent. Taken together, these results might be in accordance with if folk use for pain- and inflammation-related symptoms.

Leurieus quinquestriatus scorpion venom ameliorates adjuvant-induced arthritis in rats: Modulating JAK/STAT/RANKL signal transduction pathway

Leurieus quinquestriatus (LQ) is a type of Egyptian scorpions. Prior studies have established the potential use of scorpion venoms in treating several autoimmune diseases. Therefore, the current study investigates the possible pharmacological effect of LQ venom in CFA-induced arthritis - through different mechanisms - by assessing different serum and tissue parameters. This study was divided into two phases: phase I was conducted to determine the lowest therapeutic dose of LQ scorpion venom, whereas phase II investigated the potential therapeutic effect of the chosen dose of LQ venom on induced arthritis through different mechanisms. The Wistar albino rats were divided equally and randomly into normal control group, LQ control group, arthritis control group, infliximab-treated group, and LQ-treated group. On day 20, blood and tissue samples were collected for further analysis of serum and tissue biomarkers as well as histopathological examination. The results revealed a potential therapeutic effect of LQ venom on arthritic-induced rats through a significant decrease in Rheumatoid Factor, Janus Kinase, Signal transducers and activators of transcription, Receptor activator of nuclear factor Kappa-B ligand, Tumor Necrosis Factor-alpha, Interleukin-6, Nuclear factor kappa-light-chain-enhancer of activated B cells and Malondialdehyde by 57%, 66%, 64%, 62%, 75%, 59%, 38%, and 69%, respectively as well as a significant increase in reduced glutathione, and Nuclear factor erythroid 2-related factor 2 by 102% and 360%, respectively. Histopathological examination of knee joint and spleen also revealed a substantial improvement, indicating the possible utilization of LQ venom in the treatment of rheumatoid arthritis.

Complete Freund's adjuvant-induced protein dysregulation correlated with mirror image pain as assessed by quantitative proteomics of the mouse spinal cord

Inflammation or trauma occurring on one side of the body can cause pathological pain on the contralateral noninjured side in a phenomenon called mirror-image pain (MIP). Although some potential mechanisms involved in MIP have been reported, including those involving the immune system and glial cells as well as neural mechanisms, the molecular mechanisms are not well understood. In this study, we aimed to understand the molecular mechanisms in MIP using quantitative proteomics and whole-cell patch clamp recordings. Behavioral test results showed that complete Freund's adjuvant could induce MIP in the mice. The results of isobaric tags for relative and absolute quantification (iTRAQ) quantitative proteomics showed that 108 proteins were dysregulated, and these proteins may represent potential targets. Furthermore, bioinformatics analysis was applied to explore the potential molecular mechanisms during MIP after complete Freund's adjuvant (CFA) treatment. Parallel reaction monitoring (PRM) results showed that PKCδ and seven other dysregulated proteins were related to MIP after CFA treatment. Patch clamp recording results showed that CFA treatment could increase intrinsic excitability and spontaneous firing in spinal cord neurons during MIP. In summary, we found that CFA could induce MIP. The results of proteomic research on the spinal cord after CFA treatment could provide new insight into the molecular mechanisms of MIP. Moreover, the neuronal activity of spinal cord neurons was upregulated during MIP after CFA treatment. In summary, the results of the spinal cord proteomic profile provide a potential molecular mechanism for understanding MIP.

Variation in essential oil components and anti-inflammatory activity of Allophylus edulis leaves collected in central-western Brazil

ETHNOPHARMACOLOGICAL RELEVANCE

An infusion obtained from the leaves of "chal-chal" (Allophylus edulis Radlk.) is used for popular treatment of intestinal disorders and as an anti-inflammatory throat treatment. Because of the anti-inflammatory medicinal folk use, a previous work reported scientific research confirming the anti-inflammatory activity of A. edulis essential oil collected in Dourados, MS, Brazil, in March 2015.

AIM OF THE STUDY

The aim of this study was to evaluate the variation in the chemical profile of the essential oil of A. edulis plants collected in Dourados (EOAE-D) and Bonito (EOAE-B), two cities in Mato Grosso do Sul State, Brazil. Additionally, we evaluated the anti-inflammatory effects of the essential oil, as well as that of the major compounds (caryophyllene oxide and α-zingiberene), in experimental in vivo models of inflammation in mice.

MATERIALS AND METHODS

Leaves were collected from plants at both sites in July 2018. The composition of the essential oil (EOAE-D and EOAE-B) was determined by GC/MS, and major compounds (caryophyllene oxide and α-zingiberene) were isolated and identified by chromatographic methods and NMR spectroscopy. Anti-inflammatory capacities were assessed using two classical models of inflammatory models, carrageenan- and CFA-induced paw inflammation (mechanical and thermal hyperalgesia).

RESULTS

Both EOAE-D and EOAE-B showed sesquiterpenes as a major constituent, namely, caryophyllene oxide (29.5%) and α-zingiberene (45.0%), respectively. In tests, EOAE, caryophyllene oxide and α-zingiberene-induced antiedematogenic and antihyperalgesic effects were found in the different utilized models.

CONCLUSIONS

The results indicate that samples from the two cities differed in chemical composition but not in their anti-inflammatory and antihyperalgesic effects. This finding corroborates the use of A. edulis as a medicinal plant and indicates its potential in the therapy of inflammatory conditions.

Sesquiterpene lactones; Damsin and neoambrosin suppress cytokine-mediated inflammation in complete Freund's adjuvant rat model via shutting Akt/ERK1/2/STAT3 signaling

ETHNOPHARMACOLOGIAL RELEVANCE

Although Damsissa (Ambrosia maritima) is traditionally used as anti-inflammatory and diuretic, the biological activity and mechanism of action of its major constituents are to be elucidated.

AIM

to decipher the anti-arthritic potential of damsin (DMS) and neoambrosin (NMS) and to unfold their molecular signaling in complete Freund's adjuvant (CFA)-induced arthritis model.

MATERIALS AND METHODS

the right hind paw was inoculated with CFA (0.1 ml) at day 0 and 7 while treatments were started from the 14^th day and continued for 2 weeks. Rats were randomly assigned into 4 groups; normal group (NRML), CFA-induced arthritis group, CFA-induced arthritis treated with DMS and NMS (10 mg/kg/day) as 3^rd and 4^th group; respectively.

RESULTS

Throughout experimental period, treatments ameliorated the increase of paw volume, knee joint diameter and nociception tests as reflected in open field arena. Also, DSM and NMS suppressed phosphorylation of Akt, STAT-3, ERK1/2 which was further mirrored by inactivation of GSK3β and downregulation of MCP-1 together with CCN1 and NF-kβ in hind paw tissue. Concomitantly, inflammation markers; TNF-α, IL-6, -12 were lowered as confirmed microscopically during examination of hind paw tissue.

CONCLUSION

DSM and NMS-induced suppression of NF-kβ subdues clinical features of RA most probably through repression of Akt/ERK1/2/STAT3 pathway. Therefore, DMS and NMS can serve as safe and effective treatment for rheumatoid arthritis, one of the most disabling chronic, inflammatory and painful autoimmune disease.

Intrathecal Administration of an Anti-nociceptive Non-CpG Oligodeoxynucleotide Reduces Glial Activation and Central Sensitization

Inflammatory pain associates with spinal glial activation and central sensitization. Systemic administration of IMT504, a non-CpG oligodeoxynucleotide originally designed as an immunomodulator, exerts remarkable anti-allodynic effects in rats with complete Freund´s adjuvant (CFA)-induced hindpaw inflammation. However, the anti-nociceptive mechanisms of IMT504 remain unknown. Here we evaluated whether IMT504 blocks inflammatory pain-like behavior by modulation of spinal glia and central sensitization. The study was performed in Sprague Dawley rats with intraplantar CFA, and a single lumbosacral intrathecal (i.t.) administration of IMT504 or vehicle was chosen to address if changes in glial activation and spinal sensitization relate to the pain-like behavior reducing effects of the ODN. Naïve rats were also included. Von Frey and Randall-Selitto tests, respectively, exposed significant reductions in allodynia and mechanical hypersensitivity, lasting at least 24 h after i.t. IMT504. Analysis of electromyographic responses to electrical stimulation of C fibers showed progressive reductions in wind-up responses. Accordingly, IMT504 significantly downregulated spinal glial activation, as shown by reductions in the protein expression of glial fibrillary acidic protein, CD11b/c, Toll-like receptor 4 (TLR4) and the phosphorylated p65 subunit of NFκB, evaluated by immunohistochemistry and western blot. In vitro experiments using early post-natal cortical glial cultures provided further support to in vivo data and demonstrated IMT504 internalization into microglia and astrocytes. Altogether, our study provides new evidence on the central mechanisms of anti-nociception by IMT504 upon intrathecal application, and further supports its value as a novel anti-inflammatory ODN with actions upon glial cells and the TLR4/NFκB pathway. Intrathecal administration of the non-CpG ODN IMT504 fully blocks CFA-induced mechanical allodynia and hypersensitivity, in association with reduced spinal sensitization. Administration of the ODN also results in downregulated gliosis and reduced TLR4-NF-κB pathway activation. IMT504 uptake into astrocytes and microglia support the concept of direct modulation of CFA-induced glial activation.

Systemic bee venom exerts anti-arthritic and anti-inflammatory properties in a rat model of arthritis

Bee venom (BV) is widely used as a traditional China medicine to treat various conditions, including rheumatoid arthritis (RA). The aim of the present study was to evaluate the effects of systemic BV (60 mg/kg) as an anti-arthritic natural product, compare it with Methotrexate and determine the possible underlying mechanisms of BV action using complete Freund's adjuvant-induced arthritic rats. The development of signs of RA signs (knee joint circumference and arthritis scoring index) was evaluated. Erythrocyte sedimentation rate, serum tumor necrosis factor-α (TNF-α) and serum interleukin-1β (IL-1β) levels were measured at the end of the study. Histopathological examination followed by immunostaining of NF-κB (P65) was performed on the affected knee joints. Additionally, in vitro cyclooxygenase (COX) inhibition activity, carrageenan paw edema test and acetic acid writhing tests were performed to evaluate the anti-inflammatory and analgesic effects of the assessed dose and compared with diclofenac. An acute toxicity test was performed to establish the safety of BV at high doses. The results of the present study highlighted the potential of systemic BV on preventing the development of signs of RA. BV also significantly reduced serum levels of TNF-α, IL-1β and NF-κB in the affected joints. In addition to its potent analgesic activity, BV exhibited favorable inhibitory activity of the COX pathway in both in vivo and in vitro models. Therefore, high dose administration of systemic BV displayed safe and promising anti-arthritic, anti-inflammatory and analgesic properties through regulation of different mechanisms associated with the pathogenesis of RA.

The P2Y14 receptor in the trigeminal ganglion contributes to the maintenance of inflammatory pain

P2Y purinergic receptors expressed in neurons and satellite glial cells (SGCs) of the trigeminal ganglion (TG) contribute to inflammatory and neuropathic pain. P2Y₁₄ receptor expression is reported in the spinal cord, dorsal root ganglion (DRG), and TG. In present study, the role of P2Y₁₄ receptor in the TG in inflammatory orofacial pain of Sprague-Dawley (SD) rats was investigated. Peripheral injection of complete Freund's adjuvant (CFA) induced mechanical hyperalgesia with the rapid upregulation of P2Y₁₄ receptor, glial fibrillary acidic protein (GFAP), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), C-C chemokine CCL2, phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2), and phosphorylated p38 (p-p38) proteins in the TG. Furthermore, immunofluorescence staining confirmed the CFA-induced upregulation of P2Y₁₄ receptor. Double immunostaining showed that P2Y₁₄ receptor colocalized with glutamine synthetase (GS) and neuronal nuclei (NeuN). Finally, trigeminal injection of a selective antagonist (PPTN) of P2Y₁₄ receptor attenuated CFA-induced mechanical hyperalgesia. PPTN also decreased the upregulation of the GFAP, IL-1β, TNF-α, CCL2, p-ERK1/2, and p-p38 proteins. Our findings showed that P2Y₁₄ receptor in TG may contribute to orofacial inflammatory pain via regulating SGCs activation, releasing cytokines (IL-1β, TNF-α, and CCL2), and phosphorylating ERK1/2 and p38.

Antihyperalgesic Activity of Quillaic Acid Obtained from Quillaja Saponaria Mol

BACKGROUND

Quillaja saponaria Mol. bark contains a high concentration of triterpene saponins that have been used for centuries as a cleansing, antiinflammatory and analgesic agent in Chilean folk medicine. In earlier studies, in mice, both the anti-inflammatory as well as the antinociceptive effect of the major sapogenin, quillaic acid have been demonstrated (QA).

OBJECTIVE

To determine the antihyperalgesic effect of QA one and seven days after itpl administration of complete Freund's adjuvant (CFA) in male mice using the hot plate test in the presence of complete Freund's adjuvant (HP/CFA) as an acute and chronic skeletal muscle pain model.

METHODS

The present study evaluated the antihyperalgesic activity of QA against acute and chronic skeletal muscle pain models in mice using the hot plate test in the presence of complete Freund's adjuvant (HP/CFA), at 24 h (acute assay) and 7 days (chronic assay) , with dexketoprofen (DEX) as the reference drug.

RESULTS

In acute and chronic skeletal muscle pain assays, QA at 30 mg/kg ip elicited its maximal antihyperalgesic effects (65.0% and 53.4%) at 24 h and 7 days, respectively. The maximal effect of DEX (99.0 and 94.1 at 24 h and 7 days, respectively) was induced at 100 mg/kg.

CONCLUSION

QA and DEX elicit dose-dependent antihyperalgesic effects against acute and chronic skeletal muscle pain, but QA is more potent than DEX in the early and late periods of inflammatory pain induced by CFA.

Evaluation of the anti-arthritic activity of Cinnamomum cassia bark extract in experimental models

BACKGROUND

Cinnamomum cassia iswidely used as a traditional medicinal plant for the treatment of rheumatoid arthritis.

OBJECTIVE

The present study aimed to assess the anti-arthritic activity of C. cassia bark hydroalcoholic extract (CCHE) in different arthritic animal models.

METHODS

In formaldehyde model, sub-plantar administration of 0.1 ml of formaldehyde (2% v/v) into the right hind paws of Wistar albino rats on days 0 and 3. The rats were divided into six groups as follows: normal control, disease control, indomethacin group (3 mg/kg, p.o.) and three groups, treated with 50, 100 and 200 mg/kg CCHE (p.o.). Joint diameter was measured, and ankle joints were collected for MDA and GSH measurements. In complete Freund's adjuvant (CFA)-induced arthritis model, CFA was injected into the sub-plantar surface of the right hind paw in rats. Joint diameter was measured, and serum TNF-α and IL-1β were measured. Histopathological and immunohistochemical analyses were also performed.

RESULTS

CCHE treatment significantly (p < 0.01) reduced MDA levels and joint swelling in a concentration-dependent manner in rats with formaldehyde-induced arthritis, in which GSH levels were elevated (p < 0.01). In rats with CFA-induced arthritis, CCHE treatment significantly reduced joint swelling as well as IL-1β and TNF-α levels (p < 0.01). TNF-α receptor expression was decreased in rats treated with indomethacin or CCHE.

CONCLUSION

Based on these findings, it can be concluded that C. cassia possesses anti-arthritic properties.

Expression of acetyl-histone H3 and acetyl-histone H4 in dorsal root ganglion and spinal dorsal horn in rat chronic pain models

AIMS

Histone acetylation and deacetylation are two histone posttranslational modifications that are usually controlled by histone acetyltransferases (HATs) and histone deacetylases (HDACs). Although HATs or HDACs Inhibitors could relieve pain hypersensitivities in chronic pain animal models, it is not clear on the expression of global histone acetylation in the dorsal root ganglion (DRG) or spinal dorsal horn in chronic pain conditions.

MAIN METHODS

A spinal nerve ligation (SNL)-induced neuropathic pain model and a complete Freund's adjuvant (CFA)-induced inflammatory pain model in rats were used to examine the expression of total acetyl-histone H3 (AcH3) and total acetyl-histone H4 (AcH4) by immunofluorescence or western blot.

KEY FINDINGS

AcH3 and AcH4 not only localized in neuronal nuclei, but also in nuclei of glial cells in the DRG. Unilateral SNL induced the increase of AcH3 and AcH4 expression in the injured lumbar 5 (L5) DRG, but not in the uninjured L5 DRG or the spinal dorsal horn, while unilateral intraplantar injection of CFA increased AcH3 and AcH4 expression in the ipsilateral L4/5 spinal dorsal horn, but not in the L4/5 DRG.

SIGNIFICANCE

These results provide morphological evidence for global histone acetylation expression in the DRG and spinal cord and indicate the differential expression in the DRG and spinal dorsal horn in different chronic pain models. More precise epigenetic mechanisms of histone acetylation on the target genes need to be revealed.

Effects of co-treatment with pioglitazone and methotrexate on experimentally induced rheumatoid arthritis in Wistar albino rats

OBJECTIVES:

Rheumatoid arthritis (RA) is a chronic inflammatory disease primarily affecting the synovial joints of the body. Methotrexate (MTX) is considered as a mainstay in the management of RA. However, monotherapy with MTX in RA is often limited by potential long-term toxicity. The present study was conducted to evaluate if MTX-pioglitazone combination therapy has an add-on benefit over monotherapy with MTX or pioglitazone on disease activity in male Wistar rats in adjuvant-induced arthritis model.

MATERIALS AND METHODS:

Arthritis was induced by single subcutaneous injection of complete Freund's adjuvant (CFA) in thirty male Wistar albino rats. They were then divided into five equal groups, which included two control groups (arthritic and nonarthritic), pioglitazone-treated (1.35 mg/kg daily), MTX-treated (0.225 mg/kg daily), and MTX + pioglitazone-treated. The disease-modifying action of the drugs was assessed by various physiological, hematological, and biochemical parameters along with histopathological and radiological analysis of affected joints. The experimental data were statistically assessed by one-way ANOVA.

RESULTS:

There was a significant reduction of disease activity in the MTX monotherapy group when compared with disease control. However, pioglitazone monotherapy group failed to demonstrate any significant effect on disease activity. The MTX-pioglitazone combination group demonstrated greater suppression of disease activity as compared to MTX and pioglitazone monotherapy and disease control group (P < 0.05).

CONCLUSION:

The present study demonstrates that the combination therapy of MTX with pioglitazone offers better control of disease activities in RA as compared to MTX or pioglitazone monotherapy.

Antipsoriatic activity of ethanolic extract of Woodfordia fruticosa (L.) Kurz flowers in a novel in vivo screening model

Objectives:

The aim of this study was to investigate the antipsoriatic activity of ethanolic extract of Woodfordia fruticosa flowers (EEWF) using a novel in vivo screening model.

Materials and Methods:

For induction of psoriasis, 0.1 ml of prepared complete Freund's adjuvant (CFA) and formaldehyde mixture (1:10 ratio) was topically applied for 7 days on the dorsum surface of the skin of Swiss albino mice. Psoriasis severity index (PSI) was evaluated by phenotypic (redness, erythema, and scales) and histological features (epidermal thickness). Therapeutic effect of 0.05% and 0.1% (w/w) ointments of EEWF was evaluated after the induction of psoriasis. Ointments of EEWF flowers were applied once daily for 3 weeks, and antipsoriatic activity was evaluated by scoring the PSI and histological examination.

Results:

We observed the phenotypic and histological features and found a progressive reduction (P < 0.05) in the severity of psoriatic lesions (redness, erythema, and scales) from day 7 to 21^st day and decreased epidermal thickness in animals treated with 0.05% and 0.1% (w/w) ointments of EEWF.

Conclusions:

The results showed that 0.05% and 0.1% (w/w) ointments of EEWF have dose-dependent beneficial effects in CFA and formaldehyde-induced psoriasis. The present investigation revealed that W. fruticosa flowers possess potent antipsoriatic activity and can be used for psoriasis treatment.

Anti-inflammatory and anti-granuloma activity of Berberis aristata DC. in experimental models of inflammation

Objective:

Berberis aristata (Berberidaceae) is an important medicinal plant used in traditional system of medicine for the treatment of rheumatoid arthritis and other inflammatory disorders. The aim of the present study is to scientifically validate the traditional use of BA in the treatment of inflammatory disorders.

Materials and Methods:

Anti-inflammatory and anti-granuloma activity of BA hydroalcoholic extract (BAHE) were evaluated in experimental models, viz., carrageenan-induced paw edema, cotton pellet-induced granuloma formation, and complete Freund's adjuvant-induced stimulation of peritoneal macrophages in rats. Expression of inflammatory mediators, viz., tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), IL-6, IL-10, TNF-R1, and cyclooxygenase-2 (COX-2) was carried out in serum and peritoneal macrophages to derive the plausible mechanism of BAHE in activated peritoneal macrophages.

Results:

Pretreatment with BAHE produced a dose-dependent reduction (P < 0.01) in carrageenan-induced paw edema and cotton pellet-induced granuloma model. BAHE treatment produced significant (P < 0.01) reduction in serum inflammatory cytokine levels as compared to control. Protein expression of pro-inflammatory markers, IL-1β, IL-6, TNF-R1, and COX-2, was found to be reduced in stimulated macrophages whereas anti-inflammatory cytokine, IL-10, was upregulated in peritoneal macrophages.

Conclusion:

The result of the present study thus demonstrates the anti-inflammatory and anti-granuloma activity of BAHE which may be attributed to its inhibitory activity on macrophage-derived cytokine and mediators.

The effect of inflammation on sympathetic nerve mediated contractions in rat isolated caudal artery

Chronic inflammatory process(es) contributes to changes in vascular function in a variety of diseases. Sympathetic nerve-mediated responses in blood vessels play a pivotal role in regular physiological functions. We tested the hypothesis that sympathetic neuro-effector function will be altered as consequence of inflammatory state. Sympathetic nerve-mediated contractions and alpha adrenergic receptor expressions were evaluated in isolated caudal arteries of rats treated with saline and Complete Freund's adjuvant (CFA). While CFA-treated animals had significantly higher plasma levels of tumor necrosis factor-alpha compared to saline, blood pressure remained unchanged. Immunofluorescence revealed increased expression of ionized calcium adapter binding molecule-1 in the adventitia of blood vessels from CFA-treated animals compared to saline. In isolated arteries, electrical field stimulations between 1.25 and 40Hz resulted in frequency-dependent contractions that wasabolished by tetrodotoxin. Neurogenic contractions from CFA groups were significantly greater than saline. While the presence of alpha₁-adrenoceptor antagonist (prazosin) significantly inhibited contractions at lower frequencies of stimulation (1.25-5Hz) in isolated arteries of CFA-treated rats compared to controls, alpha₂-adrenoceptor antagonist (rauwolscine) had modest effects. Inhibition of neuronal reuptake by cocaine comparably enhanced field-stimulated responses in vessels of experimental and control animals. Immunofluorescence revealed a difference in expression of alpha₁- and alpha₂-adrenoceptors in the endothelium of blood vessels of CFA compared to saline controls. Collectively, our observations lend support to enhanced neurogenic contractions in blood vessels of inflamed animals possibly attributing to alterations in responsiveness and/or distribution of post-junctional alpha₁-adrenoceptors.

Celecoxib attenuates depressive-like behavior associated with immunological liver injury in C57BL/6 mice through TNF-α and NF-κb dependent mechanisms

AIM

Depression associating patients with chronic liver diseases is a major treatment goal. This study aimed to evaluate the potential hepatoprotective and antidepressant effects of celecoxib in a model of experimental autoimmune hepatitis (EAH) and depressive-like behavior in C57BL/6 mice.

MAIN METHODS

EAH was induced by immunization with S-100 liver antigen emulsified in complete Freund's adjuvant (CFA). Mice were randomly allocated to 5 groups; control phosphate buffered saline group; control CFA group; EAH group, and 2 groups of EAH plus celecoxib (7.5 or 15mg/kg/d respectively). Mice were assessed behaviorally by novelty-suppressed test, tail suspension test, locomotor assessment and forced swimming tests. Serum liver enzymes and hepatic hydroxyproline content were biochemically analyzed. Histopathological analysis for liver and brain sections and immunohistochemical studies for hepatic and hippocampal tumor necrosis factor (TNF-α), nuclear factor Kappa-B (NF-κB) and caspase-3 were performed.

KEY FINDINGS

EAH group exhibited significant depressive-like changes, increase in liver enzymes and hepatic hydroxyproline content. Signs of autoimmune hepatitis and structural changes in hippocampus were confirmed by histopathological studies. Immunohistochemical examination revealed overexpression of hepatic and hippocampal TNF-α, NF-κB and caspase-3 positive cells. Celecoxib (7.5mg/kg/d) significantly ameliorated hepatic biochemical changes, hepatic and hippocampal histopathological and immunohistochemical changes induced in EAH group. Celecoxib (15mg/kg/d) significantly ameliorated the behavioral changes, histopathological and immunohistochemical changes in hippocampus, with non-significant change in hepatic biochemical profile, histopathological and immunohistochemical changes induced in EAH group.

SIGNIFICANCE

The celecoxib (7.5mg/kg/d) through its anti-inflammatory effect may represent a new therapeutic approach to treat autoimmune hepatitis associated with depressive symptoms.

Effect of ethanol extract of an ayurvedic preparation (Pathyadya Churna) on arthritis in rats

OBJECTIVES

To study the anti-arthritic activity of Pathyadya Churna ethanol extract (PCE) in rats.

MATERIALS AND METHODS

Formaldehyde (2% v/v) or complete Freund's adjuvant (CFA 0.l mL) was injected in the left hind paw of male Wistar rats to develop arthritis. These rats were treated with three doses (135, 270, and 540 mg/kg) of PCE and one dose (10 mg/kg) of indomethacin. Anti-arthritic activity of the extract was assessed by noting paw volumes, rheumatoid factor (RF), blood parameters, and histological changes.

RESULTS

PCE treatment reduced paw swelling in arthritis caused by both formaldehyde and CFA. In CFA-treated rats, a significant decrease (P < 0.001) was seen in hemoglobin (13.92 g/dL to 9.97 g/dL), red blood cell count (7.32 million/mm(3) to 6.58 million/mm(3)), and packed cell volume (44.04% to 30.56%). There were also significant (P < 0.001) elevations in white blood cell count (8220/-11,420/mm(3)), platelets (2.46-4.15 lakhs/mL), erythrocyte sedimentation rate (3.76-8.03/60 min), RF (7.17-26.77 IU/mL), triglycerides (71.69-96.60 mg/dL), total cholesterol (96.85-145.05 mg/dL), low-density lipoprotein (53.11-109.60 mg/dL), and very low-density lipoprotein (14.34-19.32 mg/dL). In CFA-induced arthritic rats, high-density lipoprotein decreased significantly (29.40 mg/dL to 16.13 mg/dL). Marked changes were noted in the histology of ankles. Treatment with PCE significantly reversed all these hematological and histological changes in a dose-dependent manner.

CONCLUSIONS

PCE has a significant anti-arthritic activity in rats and is free from toxic effects.

Adjuvant-induced mono-arthritis potentiates cerebral hemorrhage in the spontaneously hypertensive rats

AIMS

Patients with rheumatoid arthritis (RA), have a higher incidence of hypertension and stroke than the normal population. Currently there exists no animal model to study the pathogenic interactions of hemorrhagic stroke (HS) subsequent to chronic inflammation and hypertension. We have created and defined a hypertensive-mono-arthritic animal model who demonstrate gros signs of cerebral hemorrhage in presence of mono-arthritis.

MAIN METHODS

Spontaneously hypertensive rats (SHR) were fed either a high salt diet (4% NaCl; HSD) or Purina chow (RD) from weaning. Complete Freund's adjuvant (CFA) was injected into the left hind paw at 21-28weeks (control groups received saline (SAL)). Degree of inflammation, joint swelling, weight and blood pressure were monitored for 21days. Animals were then sacrificed and their brain and left hind paw evaluated.

KEY FINDINGS

All groups were hypertensive throughout the experimental period (>180mmHg systolic), irrespective of diet. Both CFA groups produced significant local inflammatory response in their injected paw with associated joint degradation and cellular infiltrates. Systemic plasma TNF-α levels were significantly elevated in CFA groups, with significant increase in TNF-α at 7 and 14days, compared to SAL groups. Cerebral hemorrhage was visualized in the CFA groups but not SAL controls, with a higher severity in HSD-CFA group.

SIGNIFICANCE

The mono-arthritic hypertensive animals are capable of developing HS upon induction of inflammatory insult. The HSD appears to exacerbate the inflammatory response and influence degree of the hemorrhage. Our novel, multi-disease model may provide an appropriate platform to study the pathogenesis of HS among arthritic patients.

Optical isomers of phenibut inhibit [H(3)]-Gabapentin binding in vitro and show activity in animal models of chronic pain

BACKGROUND

We report that R- and S-phenibut (β-phenyl-γ-aminobutyric acid) - derivatives of GABA - bind with an affinity of c.a. 90μM to the gabapentin binding site in a competitive assay, a value comparable to that for previously claimed targets for this enantioermic molecule. This finding implied potential activity in neuropathic pain, this being one of the clinically validated indications for gabapentin.

METHODS

The effect of phenibut on tactile allodynia was tested in a chronic constriction nerve injury (CCI) neuropathic pain model and against hypersensitivity following inflammation induced by inoculation using complete Freund's adjuvant (CFA) model.

RESULTS

Indeed, a significant inhibitory effect on tactile allodynia was detected in rats in both employed chronic pain models with stronger and clearly dose dependent effect with R isomer.

CONCLUSIONS

The results confirm activity in chronic pain models predicted from affinity for the gabapentin site and suggests, at least partially, that α2δ-subunits of presynaptic voltage-gated calcium channels are involved in mediating this effect.

Small molecule inhibitors of PSD95-nNOS protein-protein interactions as novel analgesics

Aberrant increases in NMDA receptor (NMDAR) signaling contributes to central nervous system sensitization and chronic pain by activating neuronal nitric oxide synthase (nNOS) and generating nitric oxide (NO). Because the scaffolding protein postsynaptic density 95kDA (PSD95) tethers nNOS to NMDARs, the PSD95-nNOS complex represents a therapeutic target. Small molecule inhibitors IC87201 (EC5O: 23.94 μM) and ZL006 (EC50: 12.88 μM) directly inhibited binding of purified PSD95 and nNOS proteins in AlphaScreen without altering binding of PSD95 to ErbB4. Both PSD95-nNOS inhibitors suppressed glutamate-induced cell death with efficacy comparable to MK-801. IC87201 and ZL006 preferentially suppressed phase 2A pain behavior in the formalin test and suppressed allodynia induced by intraplantar complete Freund's adjuvant administration. IC87201 and ZL006 suppressed mechanical and cold allodynia induced by the chemotherapeutic agent paclitaxel (ED50s: 2.47 and 0.93 mg/kg i.p. for IC87201 and ZL006, respectively). Efficacy of PSD95-nNOS disruptors was similar to MK-801. Motor ataxic effects were induced by MK-801 but not by ZL006 or IC87201. Finally, MK-801 produced hyperalgesia in the tail-flick test whereas IC87201 and ZL006 did not alter basal nociceptive thresholds. Our studies establish the utility of using AlphaScreen and purified protein pairs to establish and quantify disruption of protein-protein interactions. Our results demonstrate previously unrecognized antinociceptive efficacy of ZL006 and establish, using two small molecules, a broad application for PSD95-nNOS inhibitors in treating neuropathic and inflammatory pain. Collectively, our results demonstrate that disrupting PSD95-nNOS protein-protein interactions is effective in attenuating pathological pain without producing unwanted side effects (i.e. motor ataxia) associated with NMDAR antagonists.

Chemokine CXCL1 enhances inflammatory pain and increases NMDA receptor activity and COX-2 expression in spinal cord neurons via activation of CXCR2

Recent studies have shown that CXCL1 upregulation in spinal astrocytes is involved in the maintenance of neuropathic pain. However, whether and how CXCL1 regulates inflammatory pain remains unknown. Here we show that intraplantar injection of CFA increased mRNA and protein expressions of CXCL1 and its major receptor CXCR2 in the spinal cord at 6h and 3days after the injection. Immunofluorescence double staining showed that CXCL1 and CXCR2 were expressed in spinal astrocytes and neurons, respectively. Intrathecal injection of CXCL1 neutralizing antibody or CXCR2 antagonist SB225002 attenuated CFA-induced mechanical and heat hypersensitivity on post-CFA day 3. Patch-clamp recordings showed that CXCL1 potentiated NMDA-induced currents in lamina II neurons via CXCR2, and this potentiation was further increased in CFA-treated mice. Furthermore, intrathecal injection of CXCL1 increased COX-2 expression in dorsal horn neurons, which was blocked by pretreatment with SB225002 or MEK (ERK kinase) inhibitor PD98059. Finally, pretreatment with SB225002 or PD98059 decreased CFA-induced heat hyperalgesia and COX-2 mRNA/protein expression and ERK activation in the spinal cord. Taken together, our data suggest that CXCL1, upregulated and released by spinal astrocytes after inflammation, acts on CXCR2-expressing spinal neurons to increase ERK activation, synaptic transmission and COX-2 expression in dorsal horn neurons and contributes to the pathogenesis of inflammatory pain.

The kinin B1 receptor mediates alloknesis in a murine model of inflammation

Noxious stimuli and non-noxious mechanical stimuli elicit itch (alloknesis) instead of pain on skin lesions of patients with atopic dermatitis. We previously found that bradykinin evokes an itch-related scratching response through activation of kinin B1 receptor in skin inflamed using complete Freund's adjuvant. In this study we investigated whether alloknesis is evoked in CFA-inflamed skin and the involvement of kinin receptors. In our results, alloknesis was elicited four days after CFA-inflammation. Furthermore, pretreatment with a B1 receptor antagonist or μ-opioid receptor antagonist significantly reduced alloknesis. In contrast, treatment with a B2 receptor antagonist significantly increased alloknesis. These results suggest that the alloknesis response is mediated by the activation of kinin B1 receptor but antagonized by the B2 receptor in CFA-inflamed mice.

Experimental evaluation of anti-inflammatory effect of topical application of entada phaseoloides seeds as paste and ointment

Aims:

The study was to study the anti-inflammatory effect of topical application of different formulations of seed pulp of entada phaseoloides.

Method and Material:

After removing the shell, entada phaseoloides seeds were powdered. Paste was prepared with water and ointment with polyethylene glycol & Carbowax 3350. 32 Wister rats of either sex weighing 140-200 gram were divided into four groups, Group-I vehicle, Group-II entada phaseoloides paste, Group-III entada phaseoloides Ointment, Group-IV Diclofenac sodium Ointment. Arthritis was induced by injecting 0.1ml Complete Freund's adjuvant in sub plantar region of the left hind paw. Drug treatment was started on the same day and given for 12 days. Paw volume was measured with Plethysmometer on day 0, 1, 5, 12 and 21 for both the paws. Bodyweight and Gait was observed throughout the study.

Results:

Localized inflammatory reaction developed in all the rats in 24 hours. In control group, there was no resolution of swelling even in 21 days. Both EP formulations showed significant (P < 0.001) anti-inflammatory activity as compared to control. entada phaseoloides ointment was equi-effective to that of Diclofenac sodium on 12^th day. entada phaseoloides paste was significantly (P < 0.05) more effective than Diclofenac sodium on 21^st day.

Conclusion:

Both the formulations of entada phaseoloides have anti-inflammatory activity and entada phaseoloides paste is significantly more effective than diclofenac sodium.