Search

Background: Temporomandibular joint (TMJ) receives rich sympathetic innervations that may contribute to TMJ pain through the local release of sympathomimetic amines. The aim of this study was to determine whether blockade of β-adrenoceptors in the TMJ of male and female rats reduces formalin-induced TMJ nociceptive behaviour.Methods: We co-administrated each one of the selective β(1) -, β(2) - and β(3) -adrenoceptors antagonists, atenolol, ICI 118.551 and SR59230A, respectively, with formalin in the TMJ of male and proestrus and dioestrus female rats. Because intra-temporomandibular joint formalin induces significantly different concentration-dependent responses among the three groups, with dioestrus females showing greater responses than males or proestrus females, equi-nociceptive formalin concentrations were used to test the effects of the β-adrenoceptor antagonists.Results: We found that atenolol, ICI 118.551 and SR59230A significantly reduced formalin-induced TMJ nociception in a dose response fashion in both males and females. However, a lower dose of each β-adrenoceptor antagonist was sufficient to significantly reduce nociceptive responses in females than in males. Administration of the highest doses of each β-adrenoceptor antagonist in the TMJ contralateral to that receiving formalin did not affect formalin-induced nociception in males and females, confirming the local action of the β-adrenoceptor antagonists.Conclusions: We conclude that blockade of β-adrenoceptors in the temporomandibular joint suppresses formalin-induced TMJ nociceptive behaviour in both males and females but females are more responsive. These findings suggest that the use of β-blockers in the treatment of TMJ pain might be of benefit, especially in females. [ABSTRACT FROM AUTHOR]

In Brazil studies with native medicinal plants are usually performed using non-domesticated plants and as a result the genetic variability of wild species could express different levels of active principles changing their therapeutic effect. Based on that, the aim of this study was to demonstrate that extract of different half- sib families Cordia verbenacea (DC), widely used as medicinal plant in Brazil, have different efficacy in the Total Growth Inhibition (TGI) of 5 different human tumor cell lines. Data were statistically analyzed using ANOVA follow by Tuckey test and a heritability estimation of the plant families was performed. The results showed that TGI are different for each plant family according with each human tumor cell line. For instance, extracts obtained from families 3,11 and 12 were more effective to inhibit the U-251 and Ht-29 cell lines compared to the other families, while extracts obtained from the family 32 was more effective against thethe PC-3 line. The heritability coefficient indicated that plant population selection could promote a genetic improvement related to its active principle and their pharmacological effect and could provide the identification of the best families according to their pharmacological efficacy. In conclusion, this study suggests that the domestication of a wild medicinal plant should be better monitored by its pharmacological effect.

Background/Objectives: Intracranial Epidermoid Cysts (IECs) are rare intracranial tumors primarily treated through surgery. Cyst adherence complicates complete removal, leading to high rates of tumor progression after subtotal resection. The molecular drivers of IEC remain unknown. Consequently, advances in treatment have fallen short. Tumor genetic profiling has revealed potential targets for drug development, including FDA-approved options and reshaping treatment. The genetic landscape of IECs has not been explored. We applied Whole Exome Sequencing (WES) to IECs to gain insights into the mechanisms of oncogenesis and identify potential therapeutic targets. Methods: We performed WES on tumor tissue and matched blood samples, when available. Following GATK best practices, we conducted read processing, quality control, somatic variant calling, and copy-number inference. Data analyses and visualization were conducted in R. Results: Top altered genes are associated with the immune system and tumor microenvironment, suggesting a mechanism of immune evasion. Gene and pathway enrichment revealed a high mutation burden in genes associated with Extracellular Matrix (ECM) and PI3K-AKT-mTOR cascades. Recurrent and deleterious alterations in NOTCH2 and USP8 were identified in 50% and 30% of the cohort, respectively. Frequent amplifications in deubiquitinases and beta-defensins strengthened the involvement of immune mechanisms for oncogenic transformation. Conclusions: Top altered genes and recurrent mutations may play a role in shaping the microenvironment and modulating immune evasion in IECs. USP8 and NOTCH2 may serve as clinically relevant target for IECs. Finally, we present evidence that the crosstalk between the PI3K-Akt-mTOR and ECM signaling pathways may play a role in modulating the immune escape mechanism in IECs.

Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Carlos A Parada reports a relationship with State University of Campinas that includes: employment. The co-author, Yasmin C Nunes, is a post-graduation student fellow of CAPES - Pos Graduation Program of Brazil. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Platelet-rich plasma (PRP) is a biological blood-derived therapeutic obtained from whole blood that contains higher levels of platelets. PRP has been primarily used to mitigate joint degeneration and chronic pain in osteoarthritis (OA). This clinical applicability is based mechanistically on the release of several proteins by platelets that can restore joint homeostasis. Platelets are the primary source of brain-derived neurotrophic factor (BDNF) outside the central nervous system. Interestingly, BDNF and PRP share key biological activities with clinical applicability for OA management, such as anti-inflammatory, anti-apoptotic, and antioxidant. However, the role of BDNF in PRP therapeutic activities is still unknown. Thus, this work aimed to investigate the implications of BDNF in therapeutic outcomes provided by PRP therapy in vitro and in-vivo, using the MIA-OA animal model in male Wistar rats. Initially, the PRP was characterized, obtaining a leukocyte-poor-platelet-rich plasma (LP-PRP). Our assays indicated that platelets activated by Calcium release BDNF, and suppression of M1 macrophage polarization induced by LP-PRP depends on BDNF full-length receptor, Tropomyosin Kinase-B (TrkB). OA animals were given LP-PRP intra-articular and showed functional recovery in gait, joint pain, inflammation, and tissue damage caused by MIA. Immunohistochemistry for activating transcriptional factor-3 (ATF-3) on L4/L5 dorsal root ganglia showed the LP-PRP decreased the nerve injury induced by MIA. All these LP-PRP therapeutic activities were reversed in the presence of TrkB receptor antagonist. Our results suggest that the therapeutic effects of LP-PRP in alleviating OA symptoms in rats depend on BDNF/TrkB activity., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Meningiomas, although mostly benign, can be recurrent and fatal. World Health Organization (WHO) grading of the tumor does not always identify high-risk meningioma, and better characterizations of their aggressive biology are needed. To approach this problem, we combined 13 bulk RNA sequencing (RNA-seq) datasets to create a dimension-reduced reference landscape of 1,298 meningiomas. The clinical and genomic metadata effectively correlated with landscape regions, which led to the identification of meningioma subtypes with specific biological signatures. The time to recurrence also correlated with the map location. Further, we developed an algorithm that maps new patients onto this landscape, where the nearest neighbors predict outcome. This study highlights the utility of combining bulk transcriptomic datasets to visualize the complexity of tumor populations. Further, we provide an interactive tool for understanding the disease and predicting patient outcomes. This resource is accessible via the online tool Oncoscape, where the scientific community can explore the meningioma landscape., Competing Interests: Declaration of interests Although the majority of Oncoscape is open source, a subset of the technology and computational algorithms presented in this paper are covered by serial no. 63/595,717, and N.N., S.A., M.J., and E.C.H. are listed as inventors., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Osteoarthritis (OA) is a chronic disease that may lead to joint structure degeneration, cartilage destruction, osteophyte formation, subchondral bone disruption, and pain. In this scenario, a higher proportion of the proinflammatory macrophage type 1 (M1) than the anti-inflammatory macrophage type 2 (M2) could be highlighted as a hallmark of OA progression. The balance between these two macrophage types emerges as a new therapeutic target in OA. This study aimed to evaluate the analgesia and macrophage profile in the treatment of experimental osteoarthritis (EOA) with systemic dimethyl fumarate (DMF) or local intra-articular monomethyl fumarate (MMF)., Results: DMF via gavage or MMF via intra-articular in the right knee of EOA rats showed improvements in gait parameters and the nociceptive recovery of the mechanical threshold assessment by adapted electronic von Frey treatment on the twenty-first day (long-lasting phase). DMF treatment decreased proinflammatory TNF-α while increasing anti-inflammatory IL-10 cytokines from the macerated capsule on the fifth day (inflammatory phase). MMF treatment showed joint capsule mRNA extraction downregulating iNOS and TNF-α gene expression while upregulating IL-10 and MCP-1. However, CD206 was not significant but higher than untreated EOA rats' joints on the seventh day (inflammatory phase)., Conclusions: Our studies with EOA model induced by MIA suggest a new perspective for human treatment committed with OA based on macrophage polarization as a therapeutic target, switching the proinflammatory profile M1 to the anti-inflammatory profile M2 with DMF systematic or by MMF locally treatment according to the OA severity., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Pannexin1 (Panx1) is a membrane channel expressed in different cells of the nervous system and is involved in several pathological conditions, including pain and inflammation. At the central nervous system, the role of Panx1 is already well-established. However, in the periphery, there is a lack of information regarding the participation of Panx1 in neuronal sensitization. The dorsal root ganglion (DRG) is a critical structure for pain processing and modulation. For this reason, understanding the molecular mechanism in the DRG associated with neuronal hypersensitivity has become highly relevant to discovering new possibilities for pain treatment. Here, we aimed to investigate the role of Panx1 in acute nociception and peripheral inflammatory and neuropathic pain by using two different approaches., Methods: Rats were treated with a selective Panx1 blocker peptide (10Panx) into L5-DRG, followed by ipsilateral intraplantar injection of carrageenan, formalin, or capsaicin. DRG neuronal cells were pre-treated with 10Panx and stimulated by capsaicin to evaluate calcium influx. Panx1 knockout mice (Panx1-KO) received carrageenan or capsaicin into the paw and paclitaxel intraperitoneally. The von Frey test was performed to measure the mechanical threshold of rats' and mice's paws before and after each treatment., Results: Pharmacological blockade of Panx1 in the DRG of rats resulted in a dose-dependent decrease of mechanical allodynia triggered by carrageenan, and nociception decreased in the second phase of formalin. Nociceptive behavior response induced by capsaicin was significantly lower in rats treated with Panx1 blockade into DRG. Neuronal cells with Panx1 blockage showed lower intracellular calcium response than untreated cells after capsaicin administration. Accordingly, Panx1-KO mice showed a robust reduction in mechanical allodynia after carrageenan and a lower nociceptive response to capsaicin. A single dose of paclitaxel promoted acute mechanical pain in wildtype (WT) but not in Panx1-KO mice. Four doses of chemotherapy promoted chronic mechanical allodynia in both genotypes, although Panx1-KO mice had significant ablation in the first eight days., Conclusion: Our findings suggest that Panx1 is critical for developing peripheral inflammatory pain and acute nociception involving transient receptor potential vanilloid subtype 1 (TRPV1) but is not essential for neuropathic pain chronicity., Competing Interests: The authors declare no conflict of interest., (© 2024 The Author(s). Published by IMR Press.)

Stress substantially increases the risk of developing painful temporomandibular disorders (TMDs) by influencing the release of endogenous catecholamines. Propranolol, an antagonist of β-adrenergic receptors, has shown potential in alleviating TMD-associated pain, particularly when the level of catecholamines is elevated. The aim of this study was to explore whether intra-articular propranolol administration is effective in diminishing temporomandibular joint (TMJ) pain during repeated stress situations. Additionally, we investigated the effect of repeated stress on the expression of genes encoding β-adrenoceptors in the trigeminal ganglion. In the present study, rats were exposed to a stress protocol induced by sound, then to the administration of formalin in the TMJ (to elicit a nociceptive response), followed immediately afterward by different doses of propranolol, after which the analgesic response to propranolol was evaluated. We also assessed the levels of beta-1 and beta-2 adrenergic receptor mRNAs (Adrb1 and Adrb2, respectively) using reverse transcription-quantitative PCR (RT-qPCR). Our findings revealed that propranolol administration reduces formalin-induced TMJ nociception more effectively in stressed rats than in non-stressed rats. Furthermore, repeated stress decreases the expression of the Adrb2 gene within the trigeminal ganglion. The findings of this study are noteworthy as they suggest that individuals with a chronic stress history might find potential benefits from β-blockers in TMD treatment., (© 2023 Scandinavian Division of the International Association for Dental Research. Published by John Wiley & Sons Ltd.)

Temporomandibular disorder (TMD) is a common painful condition of the temporomandibular joint (TMJ) and associated structures. Stress is a significant risk factor for developing this painful condition that predominantly affects women. This study aimed to test the hypothesis that stress increases the risk of developing TMJ pain by facilitating inflammatory mechanisms in female and male rats. To test this hypothesis, we evaluated TMJ carrageenan-induced expression of pro-inflammatory cytokines and migration of inflammatory cells and TMJ formalin-induced nociception in female and male rats submitted to a repeated stress protocol induced by sound. We found that sound-induced repeated stress facilitates TMJ inflammation and contributes to TMJ nociception development equally in females and males. We conclude that stress is a risk factor for developing painful TMJ conditions in males and females, at least in part, by favoring the inflammatory process similarly in both sexes., (© 2023 Scandinavian Division of the International Association for Dental Research. Published by John Wiley & Sons Ltd.)

Unsuccessful anesthesia often occurs under an inflammatory tissue environment, making dentistry treatment extremely painful and challenging. Articaine (ATC) is a local anesthetic used at high (4%) concentrations. Since nanopharmaceutical formulations may improve the pharmacokinetics and pharmacodynamics of drugs, we encapsulated ATC in nanostructured lipid carriers (NLCs) aiming to increase the anesthetic effect on the inflamed tissue. Moreover, the lipid nanoparticles were prepared with natural lipids (copaiba ( Copaifera langsdorffii ) oil and avocado ( Persia gratissima ) butter) that added functional activity to the nanosystem. NLC-CO-A particles (~217 nm) showed an amorphous lipid core structure according to DSC and XDR. In an inflammatory pain model induced by λ-carrageenan in rats, NLC-CO-A improved (30%) the anesthetic efficacy and prolonged anesthesia (3 h) in relation to free ATC. In a PGE2-induced pain model, the natural lipid formulation significantly reduced (~20%) the mechanical pain when compared to synthetic lipid NLC. Opioid receptors were involved in the detected analgesia effect since their blockage resulted in pain restoration. The pharmacokinetic evaluation of the inflamed tissue showed that NLC-CO-A decreased tissue ATC elimination rate (ke) by half and doubled ATC's half-life. These results present NLC-CO-A as an innovative system to break the impasse of anesthesia failure in inflamed tissue by preventing ATC accelerated systemic removal by the inflammatory process and improving anesthesia by its association with copaiba oil.

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic inflammatory disease without consistently effective treatment. Among the many mediators implicated in cystitis, the overproduction of reactive oxygen species (ROS) seems to play a key role, although the main source of ROS remains unclear. This study aimed to investigate the contribution of NADPH oxidase (NOX) isoforms in ROS generation and the voiding dysfunction of cyclophosphamide (CYP, 300 mg/Kg, ip, 24 h)-induced cystitis in adult female mice, a well-recognized animal model to study IC/BPS, by using GKT137831 (5 mg/Kg, ip, three times in a 24 h period) or GSK2795039 (5 mg/Kg, ip, three times in a 24 h period) to inhibit NOX1/4 or NOX2, respectively. Our results showed that treatment with GSK2795039 improved the dysfunctional voiding behavior induced by CYP, reduced bladder edema and inflammation, and preserved the urothelial barrier integrity and tight junction occludin expression, besides inhibiting the characteristic vesical pain and bladder superoxide anion generation. In contrast, the NOX1/4 inhibitor GKT137831 had no significant protective effects. Taken together, our in vivo and ex vivo data demonstrate that NOX2 is possibly the main source of ROS observed in cystitis-induced CYP in mice. Therefore, selective inhibition of NOX2 by GSK2795039 may be a promising target for future therapies for IC/BPS.

Inflammation is a vital process for the injured tissue restoration and one of its hallmarks is inflammatory hyperalgesia. The cyclooxygenase (COX) pathway is strongly related to the inflammatory and painful process. Usually, the COX-1 isoform is described as homeostatic, while COX-2 is characterized as inducible in inflammatory conditions. Although it is well known that neutrophil cells are the first to arrive at the inflamed site and the major source of COX-2 is still unknown, the specific role of neutrophil-derived COX-2 in the pain process is. Thus, in the present study, we demonstrate for the first time that neutrophil-derived COX-2 plays a key role in peripheral inflammatory hyperalgesia. Conditional knockout mice for COX-2 in neutrophils (COX-2  fl/fl: Mrp8cre± ) exhibited higher pain sensitivity after carrageenan (CG) injection and long-lasting IL-1β-induced hyperalgesia compared with the control group (COX-2  fl/fl ). Also, CG-induced inflammation in COX-2  fl/fl: Mrp8cre± mice showed COX-1 overexpression, and increased neutrophil migration and pro-inflammatory cytokines (e.g., IL-1β and CXCL1). These findings revealed that neutrophil COX-2 has an important role in the regulation of inflammatory hyperalgesia., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Several recent studies have established the efficacy of photobiomodulation therapy (PBMT) in painful clinical conditions. Diabetic neuropathy (DN) can be related to activating mitogen-activated protein kinases (MAPK), such as p38, in the peripheral nerve. MAPK pathway is activated in response to extracellular stimuli, including interleukins TNF-α and IL-1β. We verified the pain relief potential of PBMT in streptozotocin (STZ)-induced diabetic neuropathic rats and its influence on the MAPK pathway regulation and calcium (Ca 2+ ) dynamics. We then observed that PBMT applied to the L4-L5 dorsal root ganglion (DRG) region reduced the intensity of hyperalgesia, decreased TNF-α and IL-1β levels, and p38-MAPK mRNA expression in DRG of diabetic neuropathic rats. DN induced the activation of phosphorylated p38 (p-38) MAPK co-localized with TRPV1 + neurons; PBMT partially prevented p-38 activation. DN was related to an increase of p38-MAPK expression due to proinflammatory interleukins, and the PBMT (904 nm) treatment counteracted this condition. Also, the sensitization of DRG neurons by the hyperglycemic condition demonstrated during the Ca 2+ dynamics was reduced by PBMT, contributing to its anti-hyperalgesic effects., (© 2022. The Author(s).)

Radiofrequency energy is a common treatment modality for chronic pain. While there are different forms of radiofrequency-based therapeutics, the common concept is the generation of an electromagnetic field in the applied area, that can result in neuromodulation (pulsed radiofrequency-PRF) or ablation. Our specific focus relates to PRF due to the possibility of modulation that is in accordance with the mechanisms of action of orthobiologics. The proposed mechanism of action of PRF pertaining to pain relief relies on a decrease in pro-inflammatory cytokines, an increase in cytosolic calcium concentration, a general effect on the immune system, and a reduction in the formation of free radical molecules. The primary known properties of orthobiologics constitute the release of growth factors, a stimulus for endogenous repair, analgesia, and improvement of the function of the injured area. In this review, we described the mechanism of action of both treatments and pertinent scientific references to the use of the combination of PRF and orthobiologics. Our hypothesis is a synergic effect with the combination of both techniques which could benefit patients and improve the life quality.

Background Activating variants in platelet-derived growth factor receptor beta (PDGFRB), including a variant we have previously described (p.Tyr562Cys [g.149505130T>C [GRCh37/hg19]; c.1685A>G]), are associated with development of multiorgan pathology, including aneurysm formation. To investigate the association between the allele fraction genotype and histopathologic phenotype, we performed an expanded evaluation of post-mortem normal and aneurysmal tissue specimens from the previously published index patient. Methods and Results Following death due to diffuse subarachnoid hemorrhage in a patient with mosaic expression of the above PDGFRB variant, specimens from the intracranial, coronary, radial and aortic arteries were harvested. DNA was extracted and alternate allele fractions (AAF) of PDGFRB were determined using digital droplet PCR. Radiographic and histopathologic findings, together with genotype expression of PDGFRB were then correlated in aneurysmal tissue and compared to non-aneurysmal tissue. The PDGFRB variant was identified in the vertebral artery, basilar artery, and P1 segment aneurysms (AAF: 28.7%, 16.4%, and 17.8%, respectively). It was also identified in the coronary and radial artery aneurysms (AAF: 22.3% and 20.6%, respectively). In phenotypically normal intracranial and coronary artery tissues, the PDGFRB variant was not present. The PDGFRB variant was absent from lymphocyte DNA and normal tissue, confirming it to be a non-germline somatic variant. Primary cell cultures from a radial artery aneurysm localized the PDGFRB variant to CD31-, non-endothelial cells. Conclusions Constitutive expression of PDGFRB within the arterial wall is associated with the development of human fusiform aneurysms. The role of targeted therapy with tyrosine kinase inhibitors in fusiform aneurysms with PDGFRB mutations should be further studied.

Intracellular peptides (InPeps) generated by proteasomes were previously suggested as putative natural regulators of protein-protein interactions (PPI). Here, the main aim was to investigate the intracellular effects of intracellular peptide VFDVELL (VFD7) and related peptides on PPI. The internalization of the peptides was achieved using a C-terminus covalently bound cell-penetrating peptide (cpp; YGRKKRRQRRR). The possible inhibition of PPI was investigated using a NanoBiT ® luciferase structural complementation reporter system, with a pair of plasmids vectors each encoding, simultaneously, either FK506-binding protein (FKBP) or FKBP-binding domain (FRB) of mechanistic target of rapamycin complex 1 (mTORC1). The interaction of FKBP-FRB within cells occurs under rapamycin induction. Results shown that rapamycin-induced interaction between FKBP-FRB within human embryonic kidney 293 (HEK293) cells was inhibited by VFD7-cpp (10-500 nM) and FDVELLYGRKKRRQRRR (VFD6-cpp; 1-500 nM); additional VFD7-cpp derivatives were either less or not effective in inhibiting FKBP-FRB interaction induced by rapamycin. Molecular dynamics simulations suggested that selected peptides, such as VFD7-cpp, VFD6-cpp, VFAVELLYGRKKKRRQRRR (VFA7-cpp), and VFEVELLYGRKKKRRQRRR (VFA7-cpp), bind to FKBP and to FRB protein surfaces. However, only VFD7-cpp and VFD6-cpp induced changes on FKBP structure, which could help with understanding their mechanism of PPI inhibition. InPeps extracted from HEK293 cells were found mainly associated with macromolecular components (i.e., proteins and/or nucleic acids), contributing to understanding InPeps' intracellular proteolytic stability and mechanism of action-inhibiting PPI within cells. In a model of cell death induced by hypoxia-reoxygenation, VFD6-cpp (1 µM) increased the viability of mouse embryonic fibroblasts cells (MEF) expressing mTORC1-regulated autophagy-related gene 5 (Atg5), but not in autophagy-deficient MEF cells lacking the expression of Atg5. These data suggest that VFD6-cpp could have therapeutic applications reducing undesired side effects of rapamycin long-term treatments. In summary, the present report provides further evidence that InPeps have biological significance and could be valuable tools for the rational design of therapeutic molecules targeting intracellular PPI.

Intracranial saccular aneurysms (ISA) represent 90%-95% of all intracranial aneurysm cases, characterizing abnormal pockets at arterial branch points. Ruptures lead to subarachnoid hemorrhages (SAH) and poor prognoses. We applied mass spectrometry-based peptidomics to investigate the peptidome of twelve cerebrospinal fluid (CSF) samples collected from eleven patients diagnosed with ISA. For peptide profile analyses, participants were classified into: 1) ruptured intracranial saccular aneurysms (RIA), 2) unruptured intracranial saccular aneurysms (UIA), and late-ruptured intracranial saccular aneurysms (LRIA). Altogether, a total of 2199 peptides were detected by both Mascot and Peaks software, from which 484 (22.0%) were unique peptides. All unique peptides presented conserved chains, domains, regions of protein modulation and/or post-translational modification sites related to human diseases. Gene Ontology (GO) analyses of peptide precursor proteins showed that 42% are involved in binding, 56% in cellular anatomical entities, and 39% in intercellular signaling molecules. Unique peptides identified in patients diagnosed with RIA have a larger molecular weight and a distinctive developmental process compared to UIA and LRIA (P ≤ 0.05). Continued investigations will allow the characterization of the biological and clinical significance of the peptides identified in the present study, as well as identify prototypes for peptide-based pharmacological therapies to treat ISA. SIGNIFICANCE., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The most frequently used local anesthetics (LA) for local infiltration have an ionizable amine in the range of pH 7.6-8.9. Effective anesthesia of inflamed tissues is a great challenge, especially because the induced local acidosis decreases the fraction of the neutral (more potent) LA species in situ. To solve this limitation, the butyl-substituted benzocaine analogue butamben (BTB) - that has no ionizable amine group close to the physiological pH - could be useful if it was not for its low solubility. To overcome the solubility problem, an optimized formulation for BTB using nanostructured lipid carriers (NLC) was developed by a factorial design and characterized using DLS, XRD, DSC and cryo-EM. The release kinetics and cytotoxicity of the new formulation were measured in vitro, while the in vivo tests assessed its effectiveness on healthy and inflamed tissues, in rats. The optimized NLCBTB formulation showed desirable physicochemical properties (size = 235.6 ± 3.9 nm, polydispersity = 0.182 ± 0.006 and zeta potential = -23.6 ± 0.5 mV), high (99.5%) encapsulation efficiency and stability during 360 days of storage at room temperature. NLCBTB prolonged the release of butamben and decreased its in vitro cytotoxicity without inducing any in vivo toxic alteration. In the inflammatory hyperalgesia model, the NLCBTB formulation showed potential for the management of inflammatory pain, displaying greater analgesic effectiveness (40%) and a prolonged effect.

The mechanism underlying the role of tumor necrosis factor alpha (TNF-α) in the development of inflammatory hyperalgesia has been extensively studied, mainly the role of TNF-α in the release of pro-inflammatory cytokines. The current concept relies in the fact that TNF-α stimulates the cascade release of other pro-inflammatory cytokines, such as IL-1β, IL-6, and IL-8 (CINC-1 in rats), triggering the release of the final inflammatory mediator prostaglandin E 2 (PGE 2 ) and sympathetic amines that directly sensitize the nociceptors. However, this may not be the sole mechanism involved as the blockade of TNF-α synthesis by thalidomide prevents hyperalgesia without interrupting the synthesis of IL-1β, IL-6, and CINC-1. Therefore, we hypothesized that activation of TNF-α receptor type 1 (TNFR1) by TNF-α increases nociceptors' susceptibility to the action of PGE 2 and dopamine. We have found out that intrathecal administration of oligodeoxynucleotide-antisense (ODN-AS) against TNFR1 or thalidomide prevented carrageenan-induced hyperalgesia. The co-administration of TNF-α with a subthreshold dose of PGE 2 or dopamine that does not induce hyperalgesia by itself in the hind paw of Wistar rats pretreated with dexamethasone (to prevent the endogenous release of cytokines) induced a robust hyperalgesia that was prevented by intrathecal treatment with ODN-AS against TNFR1. We consider that the activation of neuronal TNFR1 by TNF-α decisively increases the susceptibility of the peripheral afferent neuron to the action of final inflammatory mediators - PGE 2 and dopamine - that ultimately induce hyperalgesia. This mechanism may also underlie the analgesic action of thalidomide., (© 2020 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

Chronic pain affects significant portion of the world's population and physical exercise has been extensively indicated as non-pharmacological clinical intervention to relieve symptoms in chronic pain conditions. In general, studies on pain chronification and physical exercise intervention have focused on neuropathic pain, although chronic pain commonly results from an original inflammatory episode. Based on this, the objective of the present study was to investigate the therapeutic and preventive effect of the running wheel exercise on the persistent hyperalgesia induced by repetitive inflammatory stimulus, a rodent model that simulates clinical conditions of chronic pain that persist even with no more inflammatory stimulus present. To evaluate the therapeutic effect of physical exercise, we first induced persistent hyperalgesia through 14 days of PGE2 hind paw injections and, after that, mice have access to the regular voluntary running wheel. To evaluate the preventive effect of physical exercise, we first left the mice with access to the regular voluntary running wheel and, after that, we performed 14 days of PGE2 hind paw injection. Our results showed that voluntary running wheel exercise reduced persistent mechanical and chemical hyperalgesia intensity induced by repetitive inflammatory stimulus. In addition, we showed that this therapeutic effect is long-lasting and is observed even if started belatedly, i.e. two weeks after the development of hyperalgesia. Also, our results showed that voluntary running wheel exercise absolutely prevented persistent mechanical and chemical hyperalgesia induction. We can conclude that physical exercise has therapeutic and preventive effect on inflammatory stimulus-induced persistent hyperalgesia. Our data from animal experiments bypass placebo effects bias of the human studies and reinforce physical exercise clinical recommendations to treat and prevent chronic pain., Competing Interests: The authors have declared that no competing interests exist.

Background and Purpose: While dipyrone is a widely used analgesic, its mechanism of action is not completely understood. Recently, we have reported that the dipyrone metabolite 4-aminoantipyrine (4-AA) reduces PGE 2 -induced pain-related behaviour through cannabinoid CB 1 receptors. Here, we ascertained, in naive and PGE 2 -induced "inflamed" conditions, both in vivo and in vitro, the molecular mechanisms involved in the 4-AA-induced analgesic effects., Experimental Approach: The effect of local administration of 4-AA (160 μg per paw) on capsaicin (0.12 μg per paw) injection-induced pain-related behaviour and 4-AA's effect on 500-nM capsaicin-induced changes in intracellular calcium concentration ([Ca 2+ ] i ) in cultured primary sensory neurons were assessed in vivo and in vitro, respectively., Key Results: 4-AA reduced capsaicin-induced nociceptive behaviour in naive and inflamed conditions through CB 1 receptors. 4-AA (100 μM) reduced capsaicin-induced increase in [Ca 2+ ] i in a CB 1 receptor-dependent manner, when PGE 2 was not present. Following PGE 2 application, 4-AA (1-50 μM) increased the [Ca 2+ ] i . Although 4-AA activated both TRPV1 and TRPA1 channels, increased [Ca 2+ ] i was mediated through TRPV1 channels. Activation of TRPV1 channels resulted in their desensitisation. Blocking CB 1 receptors reduced both the excitatory and desensitising effects of 4-AA., Conclusion and Implications: CB 1 receptor-mediated inhibition of TRPV1 channels and TRPV1-mediated Ca 2+ -influx- and CB 1 receptor-dependent desensitisation of TRPV1 channels contribute to the anti-nociceptive effect of 4-AA in naive and inflamed conditions respectively. Agonists active at both CB 1 receptors and TRPV1 channels might be useful as analgesics, particularly in inflammatory conditions., (© 2020 The British Pharmacological Society.)

Peripheral neuropathy is a complication of diabetes commonly associated with pain and decline in motor compound action potential, leading to alterations in plantar pressure during gait. We identified motor impairments in streptozotocin (STZ)-induced diabetic neuropathic rats and correlated with mechanical withdrawal thresholds, establishing this correlation as a complementary method to investigate the development of chronic hyperalgesia in diabetic neuropathy., Methods: UNICAMP's Ethics Committee (protocol number 3902-1) approved all experiments. Male Lewis rats (200-250 g) received a STZ-low-dose (25 mg/kg/day) (STZ group) or 0.1 M sodium citrate buffer (SCB, control group) once a day, during five consecutive days. Diabetic rats (250 mg/dL blood glucose) were submitted to electronic von Frey and CatWalk tests at 0, 7, 14, 21, and 28 days after treatment., Results: STZ, but not SCB, induced diabetes. After the 14 th day (STZ)-induced diabetic rats showed mechanical hyperalgesia and a reduction in the hind limbs footprint intensities. At the 28 th day, rats presented alterations in spatial parameters (Maximum Contact Area; Stride Length; Print Area), which showed a strong correlation with mechanical withdrawal thresholds (r 2  = 0.97; 0.99, and 0.93, respectively)., Conclusions: Correlation between gait parameters and mechanical withdrawal thresholds enables a better experimental approach to evaluate the development of chronic hyperalgesia in the STZ-induced diabetes model. It allows a concise crosstalk of motor and sensorial functions, which are usually analyzed individually. CatWalk gait parameters can be used as a complementary tool to investigate the development of hyperalgesia in STZ-induced diabetic neuropathic rats., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Pain is a distressful experience that can have a major impact on an individual's quality of life. The need for new and better analgesics has been further intensified in light of the current opioid epidemic. Substances obtained from amphibians have been shown to contain bioactive peptides that exert analgesic effects. The genus Phyllomedusa represents an important source of peptides and bioactive components. The aim of this study was to investigate the antinociceptive effects of the skin secretion of Phyllomedusa rohdei in rodent models of pain. The crude skin extract of P. rohdei was tested in different pain models: acetic acid-induced writhing test (mice), formalin test (rats), Von Frey electronic test for hypernociception induced by PGE 2 (rats), and hot plate test (mice). Motor-impairing effects were tested using the rota-rod test. The results showed that the skin extract of P. rohdei exerted antinociceptive effects in all pain models tested. Particularly, the highest dose tested of the skin extract decreased acetic acid-induced writhing by 93%, completely blocked formalin-induced nociception both during the acute and inflammatory phases of the test, PGE 2 -induced hypernociception by 73% and increased latency to paw withdrawal in the hot plate test by 300%. The effects observed in the hot plate test were reversed by pretreatment with selective µ and κ, but not δ, opioid receptor antagonists, indicating a mechanism of action dependent on µ and κ opioid receptors. The results were not influenced by sedative effects. Further studies remain necessary to reveal the specific compounds involved in the antinociceptive effects of P. rohdei skin extract as a new therapeutic tool in pain management.

Diabetic neuropathic hyperalgesia is one of the most common diabetes complications. The physiopathological mechanism of hyperalgesia and the reason by which this condition affects only part of the diabetic patients still unclear. We tested whether an adaptation of primary afferent neurons to hyperglycemia could prevent the development of hyperalgesia. Hyperglycemia was induced in male Wistar rats by a daily administration of a low dose of streptozotocin (STZ), during five consecutive days. Glycemia and mechanical nociceptive thresholds were measured at days 0, 3, 7 and 14 after starting the streptozotocin treatment. In parallel, dorsal root ganglia (DRG) neurons were collected from healthy male Wistar rats and cultured in different glucose concentrations (mimicking slow or fast increase of hyperglycemia), and used for calcium imaging and Western blot analyses. Rats with a slow increase of glycemia did not develop hyperalgesia, while rats with a fast increase of glycemia developed hyperalgesia. DRG neurons suddenly incubated in DMEM containing a high glucose concentration showed a significant increase of calcium influx. However, DRG neurons incubated in DMEM and receiving increasing doses of glucose had the same calcium influx observed in control neurons. The activation of AMPK (α1/α2) was greater in L5-L6 DRG of hyperglycemic and non-hyperalgesic rats, when compared with hyperglycemic and hyperalgesic rats. Our data suggest that the onset speed of hyperglycemia could be related to the development of diabetic neuropathic hyperalgesia, as a maladaptive consequence associated with low activation of AMPK (α1/α2) in peripheral nociceptive neurons when the glycemia suddenly increases., (© 2020 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

We have previously shown that endogenous adenosine 5'-triphosphate (ATP), via P2X3 and P2X2/3 receptors, plays an essential role in carrageenan-induced articular hyperalgesia model in rats' knee joint. In the present study, we used the rat knee joint incapacitation test, Enzyme-Linked Immunosorbent Assay (ELISA), and myeloperoxidase enzyme activity assay, to test the hypothesis that the activation of P2X3 and P2X2/3 receptors by their agonist induces articular hyperalgesia mediated by the inflammatory mediators bradykinin, prostaglandin, sympathomimetic amines, pro-inflammatory cytokines and by neutrophil migration. We also tested the hypothesis that the activation of P2X3 and P2X2/3 receptors contributes to the articular hyperalgesia induced by the inflammatory mediators belonging to carrageenan inflammatory cascade. The non-selective P2X3 and P2X2/3 receptors agonist αβ-meATP induced a dose-dependent articular hyperalgesia, which was significantly reduced by the selective antagonists for P2X3 and P2X2/3 receptors (A-317491), bradykinin B 1 - (DALBK) or B 2 -receptors (bradyzide), β 1 -(atenolol) or β 2 -adrenoceptors (ICI-118,551), by the pre-treatment with cyclooxygenase inhibitor (indomethacin) or with the nonspecific selectin inhibitor (Fucoidan). αβ-meATP induced the release of pro-inflammatory cytokines TNFα, IL-1β, IL-6, and CINC-1, as well as the neutrophil migration. Moreover, the co-administration of A-317491 significantly reduced the articular hyperalgesia induced by bradykinin, prostaglandin E 2 (PGE 2 ), and dopamine. These findings suggest that peripheral P2X3 and P2X2/3 receptors activation induces articular hyperalgesia by an indirect sensitization of the primary afferent nociceptor of rats' knee joint through the release of inflammatory mediators. Further, they also indicate that the activation of these purinergic receptors by endogenous ATP mediates the bradykinin-, PGE 2 -, and dopamine-induced articular hyperalgesia., Competing Interests: Declaration of competing interest None declared., (Copyright © 2020. Published by Elsevier B.V.)

Recently the voltage-gated sodium (Nav) channels began to be studied as possible targets for analgesic drugs. In addition, specific Nav 1.8 blockers are currently being used to treat some types of chronic pain pathologies such as neuropathies and fibromyalgia. Nav 1.8 + fibers convey nociceptive information to brain structures belonging to the limbic system, which is involved in the pathophysiology of major depressive disorders. From this, using a model of chronic social defeat stress (SDS) and intrathecal injections of Nav 1.8 antisense, this study investigated the possible involvement of Nav 1.8 + nociceptive fibers in SDS- induced hyperalgesia in C57/BL mice. Our results showed that SDS induced a depressive-like behavior of social avoidance and increased the sensitivity to mechanical (electronic von Frey test) and chemical (capsaicin test) nociceptive stimuli. We also showed that intrathecal injection of Nav 1.8 antisense reversed the SDS-induced hyperalgesia as demonstrated by both, mechanical and chemical nociceptive tests. We confirmed the antisense efficacy and specificity in a separate no-defeated cohort through real-time PCR, which showed a significant reduction of Nav 1.8 mRNA and no reduction of Nav 1.7 and Nav 1.9 in the L4, L5 and L6 dorsal root ganglia (DRG). The present study advances the understanding of SDS-induced hyperalgesia, which seems to be dependent on Nav 1.8 + nociceptive fibers., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Peripheral inflammatory hyperalgesia depends on the sensitization of primary nociceptive neurons. Inflammation drives molecular alterations not only locally but also in the dorsal root ganglion (DRG) where interleukin-1 beta (IL-1β) and purinoceptors are upregulated. Activation of the P2X7 purinoceptors by ATP is essential for IL-1β maturation and release. At the DRG, P2X7R are expressed by satellite glial cells (SGCs) surrounding sensory neurons soma. Although SGCs have no projections outside the sensory ganglia these cells affect pain signaling through intercellular communication. Therefore, here we investigated whether activation of P2X7R by ATP and the subsequent release of IL-1β in DRG participate in peripheral inflammatory hyperalgesia. Immunofluorescent images confirmed the expression of P2X7R and IL-1β in SGCs of the DRG. The function of P2X7R was then verified using a selective antagonist, A-740003, or antisense for P2X7R administered in the L5-DRG. Inflammation was induced by CFA, carrageenan, IL-1β, or PGE 2 administered in rat's hind paw. Blockage of P2X7R at the DRG reduced the mechanical hyperalgesia induced by CFA, and prevented the mechanical hyperalgesia induced by carrageenan or IL-1β, but not PGE 2 . It was also found an increase in P2X7 mRNA expression at the DRG after peripheral inflammation. IL-1β production was also increased by inflammatory stimuli in vivo and in vitro , using SGC-enriched cultures stimulated with LPS. In LPS-stimulated cultures, activation of P2X7R by BzATP induced the release of IL-1β, which was blocked by A-740003. In summary, our data suggest that peripheral inflammation leads to the activation of P2X7R expressed by SGCs at the DRG. Then, ATP-induced activation of P2X7R mediates the release of IL-1β from SGC. This evidence places the SGC as an active player in the establishment of peripheral inflammatory hyperalgesia and highlights the importance of the events in DRG for the treatment of inflammatory diseases., (Copyright © 2020 Neves, Farias, de Magalhães, Araldi, Pagliusi, Tambeli, Sartori, Lotufo and Parada.)

Dipyrone is an analgesic pro-drug used clinically to control moderate pain with a high analgesic efficacy and low toxicity. Dipyrone is hydrolyzed to 4-methylaminoantipyrine (4-MAA), which is metabolized to 4-aminoantipyrine (4-AA). Here, were investigate the involvement of peripheral cannabinoid CB 2 and opioid receptor activation in the local antihyperalgesic effect of dipyrone and 4-MAA. The inflammatory agent, carrageenan was administered to the hindpaw of male Wistar rats, and the mechanical nociceptive threshold was quantified by electronic von Frey test. Dipyrone or 4-MAA were locally administered 2.5 h after carrageenan. Following dipyrone injection, hindpaw tissue was harvested and its hydrolysis to 4-MAA was analyzed by mass spectrometry (MS). The selective CB 2 receptor antagonist (AM630), naloxone (a non-selective opioid receptor antagonist), nor-BNI (a selective kappa-opioid receptor), CTOP (a selective mu-opioid receptor), or naltrindole (a selective delta-opioid receptor) was administered 30 min prior to 4-MAA. The results demonstrate that carrageenan-induced mechanical hyperalgesia was inhibited by dipyrone or 4-MAA in a dose-dependent manner. Dipyrone administered to the hindpaw was completely hydrolyzed to 4-MAA. The antihyperalgesic effect of 4-MAA was completely reversed by AM630, naloxone and nor-BNI, but not by CTOP or naltrindole. These data suggest that the local analgesic effect of dipyrone is mediated by its hydrolyzed bioactive form, 4-MAA and, at least in part, depends on CB 2 receptor and kappa-opioid receptor activation. In conclusion, the analgesic effect of dipyrone may involve a possible interaction between the cannabinoid and opioid system in peripheral tissue., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Recent findings from rodent studies suggest that high-fat diet (HFD) increases hyperalgesia independent of obesity status. Furthermore, weight loss interventions such as voluntary physical activity (PA) for adults with obesity or overweight was reported to promote pain reduction in humans with chronic pain. However, regardless of obesity status, it is not known whether HFD intake and sedentary (SED) behavior is underlies chronic pain susceptibility. Moreover, differential gene expression in the nucleus accumbens (NAc) plays a crucial role in chronic pain susceptibility. Thus, the present study used an adapted model of the inflammatory prostaglandin E2 (PGE2)-induced persistent hyperalgesia short-term (PH-ST) protocol for mice, an HFD, and a voluntary PA paradigm to test these hypotheses. Therefore, we performed an analysis of differential gene expression using a transcriptome approach of the NAc. We also applied a gene ontology enrichment tools to identify biological processes associated with chronic pain susceptibility and to investigate the interaction between the factors studied: diet (standard diet vs. HFD), physical activity behavior (SED vs. PA) and PH-ST (PGE vs. saline). Our results demonstrated that HFD intake and sedentary behavior promoted chronic pain susceptibility, which in turn was prevented by voluntary physical activity, even when the animals were fed an HFD. The transcriptome of the NAc found 2,204 differential expression genes and gene ontology enrichment analysis revealed 41 biologic processes implicated in chronic pain susceptibility. Taking these biological processes together, our results suggest that genes related to metabolic and mitochondria stress were up-regulated in the chronic pain susceptibility group (SED-HFD-PGE), whereas genes related to neuroplasticity were up-regulated in the non-chronic pain susceptibility group (PA-HFD-PGE). These findings provide pieces of evidence that HFD intake and sedentary behavior provoked gene expression changes in the NAc related to promotion of chronic pain susceptibility, whereas voluntary physical activity provoked gene expression changes in the NAc related to prevention of chronic pain susceptibility. Finally, our findings confirmed previous literature supporting the crucial role of voluntary physical activity to prevent chronic pain and suggest that low levels of voluntary physical activity would be helpful and highly recommended as a complementary treatment for those with chronic pain., (Copyright © 2020 Brandão, Bonet, Pagliusi, Zanetti, Pho, Tambeli, Parada, Vieira and Sartori.)

Major depressive disorders (MDD) and chronic pain (CP) affect significant portion of the world's population and have high comorbidity rate. Social defeat stress (SDS) model was standardized in mice and can trigger depressive-like behavior and chronic pain. Based especially on clinical trials showing an effective preventive and therapeutic effect of physical exercise on CP and symptoms associated with MDD, this study aimed to investigate if the voluntary running wheel exercise can exert these effects in mice submitted to the 10-day SDS protocol, using fluoxetine as positive control. For this, we ran two set of experiments: in the first set mice started performing voluntary running wheel exercise after submitted to SDS and, in the second set, mice performed voluntary running wheel exercise before and during SDS. Mechanical and chemical hyperalgesia was analyzed through electronic von Frey and capsaicin test, respectively. Depressive-like behavior was assessed through social interaction test. Our results showed that the voluntary running wheel exercise was more effective than fluoxetine reversing the SDS-induced persistent hyperalgesia and both, fluoxetine and voluntary running wheel exercise, was effective reversing SDS-induced social avoidance. Also, voluntary running wheel exercise is an effective tool preventing both hyperalgesia and social avoidance induced by SDS. To the best of our knowledge, this was the first study using physical exercise as a therapeutic and preventive tool for chronic pain and depressive-like behavior simultaneously induced by social stress., (Copyright © 2019 IBRO. Published by Elsevier Ltd. All rights reserved.)

Purpose: Most World Health Organization (WHO) grade I meningiomas carry a favorable prognosis. Some become clinically aggressive with recurrence, invasion, and resistance to conventional therapies (grade 1.5; recurrent/progressive WHO grade I tumors requiring further treatment within 10 years). We aimed to identify biomarker signatures in grade 1.5 meningiomas where histopathology and genetic evaluation has fallen short., Experimental Design: Mass spectrometry (MS)-based phosphoproteomics and peptide chip array kinomics were used to compare grade I and 1.5 tumors. Ingenuity Pathway Analysis (IPA) identified alterations in signaling pathways with validation by Western blot analysis. The selected biomarker was evaluated in an independent cohort of 140 samples (79/140 genotyped for meningioma mutations) by tissue microarray and correlated with clinical variables., Results: The MS-based phosphoproteomics revealed differential Ser/Thr phosphorylation in 32 phosphopeptides. The kinomic profiling by peptide chip array identified 10 phosphopeptides, including a 360% increase in phosphorylation of RB1, in the 1.5 group. IPA of the combined datasets and Western blot validation revealed regulation of AKT and cell-cycle checkpoint cascades. RB1 hyperphosphorylation at the S780 site distinguished grade 1.5 meningiomas in an independent cohort of 140 samples and was associated with decreased progression/recurrence-free survival. Mutations in NF2, TRAF7, SMO, KLF4, and AKT1 E17K did not predict RB1 S780 staining or progression in grade 1.5 meningiomas., Conclusions: RB1 S780 staining distinguishes grade 1.5 meningiomas, independent of histology, subtype, WHO grade, or genotype. This promising biomarker for risk stratification of histologically bland WHO grade I meningiomas provides insight into the pathways of oncogenesis driving these outlying clinically aggressive tumors., (©2019 American Association for Cancer Research.)

In this study, we used Raman spectroscopy as a new tool to investigate pathological conditions at the level of chemical bond alterations in biological tissues. Currently, there have been no reports on the spectroscopic alterations caused by diabetic neuropathy in the dorsal root ganglia (DRG). DRG are a target for the treatment of neuropathic pain, and the need for more effective therapies is increasing. Photobiomodulation therapy (PBMT) through infrared low-level laser irradiation (904 nm) has shown analgesic effects on the treatment of neuropathy. Thus, the aim of this study was to use Raman spectroscopy to characterize the spectral DRG identities of streptozotocin (STZ)-induced diabetic neuropathic (hyperalgesic) rats and to study the influence of PBMT over such spectra. Characteristic DRG peaks were identified at 2704, 2850, 2885, 2940, 3061 and 3160 cm -1 , whose assignments are CH 2 /CH 3 symmetric/asymmetric stretches, and C─H vibrations of lipids and proteins. DRG from hyperalgesic rats showed an increased normalized intensity of 2704, 2850, 2885 and 3160 cm -1 . These same peaks had their normalized intensity reduced after PBMT treatment, accompanied by an anti-hyperalgesic effect. Raman spectroscopy was able to diagnose spectral alterations in DRG of hyperalgesic rats and the PBMT reduced the intensity of hyperalgesia and the altered Raman spectra., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

P2X3 receptors are involved with several pain conditions. Muscle pain induced by static contraction has an important socioeconomic impact. Here, we evaluated the involvement of P2X3 receptors on mechanical muscle hyperalgesia and neutrophil migration induced by static contraction in rats. Also, we evaluated whether static contraction would be able to increase muscle levels of TNF-α and IL-1β. Male Wistar rats were pretreated with the selective P2X3 receptor antagonist, A-317491, by intramuscular or intrathecal injection and the static contraction-induced mechanical muscle hyperalgesia was evaluated using the Randall-Selitto test. Neutrophil migration was evaluated by measurement of myeloperoxidase (MPO) kinetic-colorimetric assay and the cytokines TNF-α and IL-1β by enzyme-linked immunosorbent assay. Intramuscular or intrathecal pretreatment with A-317491 prevented static contraction-induced mechanical muscle hyperalgesia. In addition, A-317491 reduced static contraction-induced mechanical muscle hyperalgesia when administered 30 and 60 min of the beginning of static contraction, but not after 30 and 60 min of the end of static contraction. Intramuscular A-317491 also prevented static contraction-induced neutrophil migration. In a period of 24 h, static contraction did not increase muscle levels of TNF-α and IL-1β. These findings demonstrated that mechanical muscle hyperalgesia and neutrophil migration induced by static contraction are modulated by P2X3 receptors expressed on the gastrocnemius muscle and spinal cord dorsal horn. Also, we suggest that P2X3 receptors are important to the development but not to maintenance of muscle hyperalgesia. Therefore, P2X3 receptors can be pointed out as a target to musculoskeletal pain conditions induced by daily or work-related activities.

The role of somatic genetic variants in the pathogenesis of intracranial-aneurysm formation is unknown. We identified a 23-year-old man with progressive, right-sided intracranial aneurysms, ipsilateral to an impressive cutaneous phenotype. The index individual underwent a series of genetic evaluations for known connective-tissue disorders, but the evaluations were unrevealing. Paired-sample exome sequencing between blood and fibroblasts derived from the diseased areas detected a single novel variant predicted to cause a p.Tyr562Cys (g.149505130T>C [GRCh37/hg19]; c.1685A>G) change within the platelet-derived growth factor receptor β gene (PDGFRB), a juxtamembrane-coding region. Variant-allele fractions ranged from 18.75% to 53.33% within histologically abnormal tissue, suggesting post-zygotic or somatic mosaicism. In an independent cohort of aneurysm specimens, we detected somatic-activating PDGFRB variants in the juxtamembrane domain or the kinase activation loop in 4/6 fusiform aneurysms (and 0/38 saccular aneurysms; Fisher's exact test, p < 0.001). PDGFRB-variant, but not wild-type, patient cells were found to have overactive auto-phosphorylation with downstream activation of ERK, SRC, and AKT. The expression of discovered variants demonstrated non-ligand-dependent auto-phosphorylation, responsive to the kinase inhibitor sunitinib. Somatic gain-of-function variants in PDGFRB are a novel mechanism in the pathophysiology of fusiform cerebral aneurysms and suggest a potential role for targeted therapy with kinase inhibitors., (Published by Elsevier Inc.)

Ethnopharmacological Relevance: Tabebuia aurea (Silva Manso) Benth. & Hook. f. ex S. Moore is used as anti-inflammatory, analgesic and antiophidic in traditional medicine, though its pharmacological proprieties are still underexplored. In the bothropic envenoming, pain is a key symptom drove by an intense local inflammatory and neurotoxic event. The antivenom serum therapy is still the main treatment despite its poor local effects against pain and tissue injury. Furthermore, it is limited to ambulatorial niches, giving space for the search of new and more inclusive pharmacological approaches., Aim of the Study: evaluation of Tabebuia aurea hydroethanolic extract (HEETa) in hyperalgesia and neuronal injury induced by Bothrops mattogrossensis venom (VBm)., Materials and Methods: Stem barks from Tabebuia aurea were extracted with ethanol and water (7:3, v/v) to yield the extract HEETa. Then, HEETa was analyzed by LC-DAD-MS and its constituents were identified. Snake venoms were extracted from adult specimens of Bothrops mattogrossensis, lyophilized and kept at -20 °C until use. Male Swiss mice, weighting 20-25 g, were used to hyperalgesia (electronic von Frey), motor impairment (Rotarod test) and tissue injury evaluation (histopatology and ATF-3 immunohistochemistry). Therefore, three experimental groups were formed: VBm (1 pg, 1 ng, 0.3 μg, 1 μg, 3 and 6 μg/paw), HEETa orally (180, 540, 720, 810 or 1080 mg/kg; 10 mL/kg, 30 min prior VBm inoculation) and VBm neutralized (VBm: HEETa, 1:100 parts, respectively). In all set of experiments a control (saline group) was used. First, we made a dose-time-response course curve of VBm's induced hyperalgesia. Next, VBm maximum hyperalgesic dose was employed to perform HEETa orally dose-time-response course curve and analyses of VBm neutralized. Paw tissues for histopathology and DRGs were collected from animals inoculated with VBm maximum dose and treated with HEETa antihyperalgesic effective dose or neutralized VBm. Paws were extract two or 72 h after VBm inoculation and DRGs, in the maximum expected time expression of ATF-3 (72 h)., Results: From HEETa extract, glycosylated iridoids were identified, such as catalpol, minecoside, verminoside and specioside. VBm induced a time and dose dependent hyperalgesia with its highest effect seen with 3 µg/paw, 2 h after venom inoculation. HEETa effective dose (720 mg/kg) decreased significantly VBm induced hyperalgesia (3 µg/paw) with no motor impairment and signs of acute toxicity. HEETa antihyperalgesic action starts 1.5 h after VBm inoculation and lasted up until 2 h after VBm. Hyperalgesia wasn't reduced by VBm: HEETa neutralization. Histopathology revealed a large hemorragic field 2 h after VBm inoculation and an intense inflammatory infiltrate of polymorphonuclear cells at 72 h. Both HEETa orally and VBm: HEETa groups had a reduced inflammation at 72 h after VBm. Also, the venom significantly induced ATF-3 expression (35.37 ± 3.25%) compared with saline group (4.18 ± 0.68%) which was reduced in HEETa orally (25.87 ± 2.57%) and VBm: HEETa (19.84 ± 2.15%) groups., Conclusion: HEETa reduced the hyperalgesia and neuronal injury induced by VBm. These effects could be related to iridoid glycosides detected in HEETa and their intrinsic reported mechanism., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Solidago chilensis (syn. microglossa) is a plant from the Asteraceae family widely distributed in South America and used to treat inflammatory diseases. In 2009, it was listed as one of the native medicinal herbal plants used in the Brazilian public health system. In addition to its anti-inflammatory properties, a recent clinical study has shown antinociceptive effects of S. chilensis, introducing a new potential medical use for this plant. The aim of the present study was to investigate the antinociceptive activity of the hydroalcoholic extract of Solidago chilensis (HESc) in rodent models of pain., Methods: The dried plant extract was obtained from its aerial parts, maintained in ethanol (100 g/l) and filtered. Rats or mice were treated with intraperitoneal injections of HESc (3, 10 or 30 mg/kg) 30 min before being submitted to writhing, 0.2%-formaline or hot-plate tests or prostaglandin E 2 (PGE 2 ) administration in the hind paw. Mechanical hypernociception and motor impairment were evaluated by electronic von Frey and rota-rod, respectively., Results: HESc dose-dependently inhibited abdominal contortions in the writhing test and attenuated phases I and II formalin-induced nociceptive behavior. Treatment with HESc also increased thermal threshold and decreased PGE 2 -induced hypernociception without promoting motor impairment., Conclusions: Our data suggest that, when systemically administered, HESc decreases nociception without inducing a sedative effect. Importantly, this effect was observed in both inflammatory and non-inflammatory models of pain and nociception, suggesting a specific non-inflammatory mechanism of HESc on pain. Our findings indicate that S. chilensis might be an important adjuvant in pain management.

Peripheral diabetic neuropathy (PDN) manifests in 50-60% of type I and II diabetic patients and is the major cause of limb amputation. Adequate therapy for PDN is a current challenge. There are evidences that the activation of the P2X4 receptor (P2X4R) expressed on microglial cells of the central nervous system takes part in the development of neuropathic pain. However, there is an open question: Is P2X4R activation on dorsal root ganglia (DRG) involved in the development of neuropathic pain? To answer this question, this study verified the involvement of P2X4R expressed in DRG cells on diabetes-induced neuropathic mechanical hyperalgesia in rats. We found that intrathecal or ganglionar (L5-DRG) administration of a novel P2X4R antagonist (PSB-15417) or intrathecal administration of oligodeoxynucleotides (ODN)-antisense against the P2X4R reversed diabetes-induced neuropathic mechanical hyperalgesia. The DRG of the diabetic neuropathic rats showed an increase in P2X4R expression, and the DRG immunofluorescence suggested that P2X4R is expressed mainly in satellite glial cells (SGC). Finally, our study showed a functional expression of P2X4R in SGCs of the rat's DRG, because the P2X4R agonist BzATP elicits an increase in intracellular calcium concentration in SGCs, which was reduced by PSB-15417. These findings indicate that P2X4R activation in DRG is essential to diabetes-induced neuropathic mechanical hyperalgesia. Therefore, this purinergic receptor in DRG could be an interesting therapeutic target for quaternary P2X4R antagonists that do not cross the hematoencephalic barrier, for the control of neuropathic pain, preserving central nervous system functions., (Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.)

Peripheral diabetic neuropathy (DN) manifests in nearly 60% of diabetic patients, being pain its most debilitating symptom. Although electrophysiological and morphological aspects are well described, little is known about its development and progression, undermining effective therapies. Hyperglycemia and insulin signaling impairment are considered the triggering events of oxidative stress observed in the dying nerves, however there are still many gaps in the knowledge of intracellular plastic changes it generates., Aims: In this study we aimed to evaluate the early transcriptome changes in DN when the first symptoms of the disease start to appear., Main Methods: Next-Generation Sequencing of messenger RNA (RNA-Seq) of L4 and L5 dorsal root ganglia (DRG) four weeks post-diabetes induction in a rat model for type 1 diabetes., Key Findings: RNA sequencing found 66 transcripts differentially expressed between diabetic and control groups, related mainly to the following biological processes: inflammation, hyperalgesia/analgesia, cell growth and cell survival. Given their roles, the differentially expressed genes suggest an attempt to switch to a survival/regenerative program., Significance: Our results show that changes in the transcriptome profile start to appear early in the course of DN and might be related to secure cell homeostasis. Hence, the present data may indicate how DRG cells are responding to hyperglycemia in its early stages and which mechanisms first fail to respond, further leading to cell damage and cell death. Early screening of cell alterations in DN might lead to more concrete targets for pharmaceutical interventions, which could more efficiently delay cell damage., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Steroidal and non-steroidal anti-inflammatory drugs (NSAIDs) are widely used to control inflammatory pain, but there is a risk of gastrointestinal bleeding and increased heart failure risk. The search for new drugs remains ongoing, and natural products are a source for potential new compounds. Mangiferin, a natural xanthone C-glucoside, has demonstrated biological activity, including anti-inflammatory and analgesic properties, but it's mechanisms are poorly understood. In this study, we investigated the mechanisms underlying the anti-inflammatory and analgesic effects of local administration of mangiferin. We employed an electronic von Frey apparatus to evaluate mechanical hyperalgesia induced by carrageenan in rats. Mangiferin (150-1200 µg/paw), administered locally into the hindpaw, prevented hyperalgesia in a dose-dependent - 150 µg (- 9%), 300 µg (- 27%, P < 0.01), 600 µg (- 77%, P < 0.001) and 1000 µg (- 93%, P < 0.001) - and local manner. Mangiferin showed decreased levels of TNF-α (P < 0.001) and CINC-1 (P < 0.001), but not IL-1β; it also prevented neutrophil migration (P < 0.01), but not the increased COX-2 expression in peripheral tissue challenged with carrageenan. To further explore the mechanisms of mangiferin actions, rats were injected with modulators of inflammation and nociception; mangiferin prevented hyperalgesia induced by IL-1β (P < 0.01), CINC-1 (P < 0.01), epinephrine (P < 0.01), 8-Br-cAMP (P < 0.01) or capsaicin (P < 0.01), but not that induced by PGE 2 or α,β-MeATP. Our study shows that mangiferin has anti-inflammatory and analgesic properties when locally administrated. The control of the inflammatory response and mechanical hyperalgesia by mangiferin depends on the inhibition of TNF-α production/release and the CINC1/epinephrine/PKA pathway, supporting its marked inhibition of inflammatory mechanical hyperalgesia., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Epidemiological studies have shown a close association between pain and depression. There is evidence showing this association as patients with depression show a high chronic pain prevalence and vice versa. Considering that social stress is critical for the development of depression in humans, we used a social defeat stress (SDS) model which induces depressive-like behavior in mice. In this model, mice are exposed to an aggressor mouse for ten days, suffering brief periods of agonistic contact and long periods of sensory contact. Some mice display social avoidance, a depressive-like behavior, and are considered susceptible, while some mice do not, and are considered resilient. Thus, we investigated the nociceptive behavior of mice submitted to SDS and the neuroplastic changes in dopaminergic mesolimbic system. Our results showed that the stressed mice (resilient and susceptible) presented a higher sensitivity to pain than the control mice in chemical and mechanical tests. We also verified that susceptible mice have higher Bdnf mRNA in the VTA compared to the resilient and control mice. The stressed mice had less mature BDNF and more truncated BDNF protein in the NAc compared with control mice. Although social stress may trigger the development of depression and hyperalgesia, these two conditions may manifest independently as social stress induced hyperalgesia even in mice that did not display depressive-like behavior. Also, increased Bdnf in the VTA seems to be associated with depressive-like behavior, whereas high levels of truncated BDNF and low mature BDNF appear to be associated with hyperalgesia induced by social defeat stress., (© 2018 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

At dorsal root ganglia, neurons and satellite glial cells (SGC) can communicate through ATP release and P2X7 receptor activation. SGCs are also interconnected by gap junctions and have been previously implicated in modulating inflammatory and chronic pain.We now present evidence that SGCs are also involved in processing acute nociception in rat dorsal root ganglia. Using primary dorsal root ganglia cultures we observed that calcium transients induced in neurons by capsaicin administration were followed by satellite glial cells activation. Only satellite glial cells response was reduced by administration of the P2X7 receptor antagonist A740003. In vivo, acute nociception induced by intraplantar injection of capsaicin in rats was inhibited by A740003 or by the gap junction blocker carbenoxolone administered at the dorsal root ganglia (L5 level). Both drugs also reduced the second phase of the formalin test. These results suggest that communication between neurons and satellite glial cells is not only involved in inflammatory or pathological pain, but also in the transmission of the nociceptive signal, possibly in situations involving C-fiber activation., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objective: We investigated whether: (1) P2 × 7 receptor activation by its agonist (BzATP) induces articular hyperalgesia in the rat's knee joint via inflammatory mechanisms and (2) activation of P2 × 7 receptors by endogenous ATP contributes to the articular hyperalgesia induced by bradykinin, TNF-α, IL-1β, CINC-1, PGE 2, and dopamine., Methods: The articular hyperalgesia was quantified using the rat knee joint incapacitation test. The knee joint inflammation, characterized by the concentration of pro-inflammatory cytokines and by neutrophil migration, was quantified in the synovial lavage fluid by ELISA and myeloperoxidase enzyme activity assay, respectively., Results: BzATP induced a dose-dependent articular hyperalgesia in the rat's knee joint that was significantly reduced by the selective antagonists for P2 × 7, bradykinin B 1 or B 2 receptors, β 1 or β 2 adrenoceptors, and by pre-treatment with Indomethacin. BzATP induced a local increase of TNF-α, IL-1β, IL-6, and CINC-1 concentration and neutrophil migration into the knee joint. The co-administration of the selective P2 × 7 receptor antagonist A-740003 significantly reduced the articular hyperalgesia induced by bradykinin and dopamine, but not by TNF-α, IL-1β, CINC-1, and PGE 2 ., Conclusions: P2 × 7 receptor activation induces articular hyperalgesia mediated by the previous inflammatory mediator release. P2 × 7 receptor-induced articular hyperalgesia is sustained by the involvement of this purinergic receptor in bradykinin and dopamine-induced hyperalgesia in the knee joint.

Background: β-Blockers reduce temporomandibular joint (TMJ) pain. We asked whether they also reduce TMJ inflammation and, if so, whether this anti-inflammatory effect contributes to its analgesic action., Methods: We measured many parameters of the inflammatory response after co-administration of the β-blocker propranolol with the inflammatory agent carrageenan in the TMJ of female rats. We also hypothesized that the activation of β-adrenoceptors in the TMJ induces nociception mediated, at least in part, by the inflammatory response. To test this hypothesis, we examined the nociceptive response induced by the activation of the β-adrenoceptors in the TMJ in female rats pretreated with thalidomide and fucoidan., Results: We found that the co-administration of propranolol with carrageenan in the TMJ of female rats significantly reduced several parameters of the inflammatory response induced by carrageenan such as plasma extravasation, neutrophil migration and the release of the pro-inflammatory cytokines TNF-α, IL-1β and CINC-1. Furthermore, the injection of the β-adrenergic receptor agonist isoproterenol in the TMJ induced nociception that was significantly reduced by thalidomide, fucoidan and by the co-administration of propranolol but not of the α-adrenergic receptor antagonist phentolamine., Conclusions: Propranolol has anti-inflammatory effects that contribute to its antinociceptive action in the TMJ of females., Significance: β-Blockers have an anti-inflammatory effect on temporomandibular joint (TMJ) that contributes to its analgesic effect. The results of this work suggest that β-blockers can be used to treat the painful conditions of TMJ, especially when they are associated with an inflammatory process., (© 2017 European Pain Federation - EFIC®.)