239 results found
Spicarova D, Nerandzic V, Muzik D, et al., 2023, Inhibition of synaptic transmission by anandamide precursor 20:4-NAPE is mediated by TRPV1 receptors under inflammatory conditions., Frontiers in Molecular Neuroscience, Vol: 16, Pages: 1-11, ISSN: 1662-5099
Transient receptor potential ion channel, vanilloid subfamily, type 1 (TRPV1) cation channel, and cannabinoid receptor 1 (CB1) are essential in the modulation of nociceptive signaling in the spinal cord dorsal horn that underlies different pathological pain states. TRPV1 and CB1 receptors share the endogenous agonist anandamide (AEA), produced from N-arachidonoylphosphatidylethanolamine (20:4-NAPE). We investigated the effect of the anandamide precursor 20:4-NAPE on synaptic activity in naive and inflammatory conditions. Patch-clamp recordings of miniature excitatory postsynaptic currents (mEPSCs) from superficial dorsal horn neurons in rat acute spinal cord slices were used. Peripheral inflammation was induced by subcutaneous injection of carrageenan. Under naive conditions, mEPSCs frequency (0.96 ± 0.11 Hz) was significantly decreased after 20 μM 20:4-NAPE application (55.3 ± 7.4%). This 20:4-NAPE-induced inhibition was blocked by anandamide-synthesizing enzyme N-acyl phosphatidylethanolamine phospholipase D (NAPE-PLD) inhibitor LEI-401. In addition, the inhibition was prevented by the CB1 receptor antagonist PF 514273 (0.2 μM) but not by the TRPV1 receptor antagonist SB 366791 (10 μM). Under inflammatory conditions, 20:4-NAPE (20 μM) also exhibited a significant inhibitory effect (74.5 ± 8.9%) on the mEPSCs frequency that was prevented by the TRPV1 receptor antagonist SB 366791 but not by PF 514273 application. Our results show that 20:4-NAPE application has a significant modulatory effect on spinal cord nociceptive signaling that is mediated by both TRPV1 and CB1 presynaptic receptors, whereas peripheral inflammation changes the underlying mechanism. The switch between TRPV1 and CB1 receptor activation by the AEA precursor 20:4-NAPE during inflammation may play an important role in nociceptive processing, hence the development of pathological pain.
Nagy I, Friston D, Cuddihy J, et al., 2023, Elevated 18:0 lysophosphatidylcholine contributes to the development of pain in tissue injury, Pain, Vol: 164, Pages: e103-e115, ISSN: 0304-3959
Tissue injuries, including burns, are major causes of death and morbidity worldwide. These injuries result in the release of intracellular molecules and subsequent inflammatory reactions, changing the tissues’ chemical milieu and leading to the development of persistent pain through activating pain-sensing primary sensory neurons. However, the majority of pain-inducing agents in injured tissues are unknown. Here, we report that, amongst other important metabolite changes, lysophosphatidylcholines (LPCs) including 18:0 LPC exhibit significant and consistent local burn injury-induced changes in concentration. 18:0 LPC induces immediate pain and the development of hypersensitivities to mechanical and heat stimuli through molecules including the transient receptor potential ion channel, vanilloid sub-family, member 1 and member 2 at least partly via increasing lateral pressure in the membrane. As levels of LPCs including 18:0 LPC increase in other tissue injuries, our data reveal a novel role for these lipids in injury-associated pain. These findings have high potential to improve patient care.
White JPM, Cibelli M, Nagy I, et al., 2023, The Emerging Pro-Algesic Profile of Transient Receptor Potential Vanilloid Type 4., Rev Physiol Biochem Pharmacol, Vol: 186, Pages: 57-93, ISSN: 0303-4240
Transient receptor potential vanilloid type 4 (TRPV4) channels are Ca2+-permeable non-selective cation channels which mediate a wide range of physiological functions and are activated and modulated by a diverse array of stimuli. One of this ion channel's least discussed functions is in relation to the generation and maintenance of certain pain sensations. However, in the two decades which have elapsed since the identification of this ion channel, considerable data has emerged concerning its function in mediating pain sensations. TRPV4 is a mediator of mechanical hyperalgesia in the various contexts in which a mechanical stimulus, comprising trauma (at the macro-level) or discrete extracellular pressure or stress (at the micro-level), results in pain. TRPV4 is also recognised as constituting an essential component in mediating inflammatory pain. It also plays a role in relation to many forms of neuropathic-type pain, where it functions in mediating mechanical allodynia and hyperalgesia.Here, we review the role of TRPV4 in mediating pain sensations.
Nagy I, Irfan J, Febrianto M, et al., 2022, DNA methylation and non-coding RNAs during tissue-injury associated pain, International Journal of Molecular Sciences, Vol: 23, Pages: 1-29, ISSN: 1422-0067
While about half of the population experience persistent pain associated with tissue damages during their lifetime, current symptom-based approaches often fail to reduce such pain to a satisfactory level. To provide better patient care, mechanism-based analgesic approaches must be developed, which necessitates a comprehensive understanding of the nociceptive mechanism leading to tissue injury-associated persistent pain. Epigenetic events leading the altered transcription in the nervous system are pivotal in the maintenance of pain in tissue injury. However, the mechanisms through which those events contribute to the persistence of pain are not fully understood. This review provides a summary and critical evaluation of two epigenetic mechanisms, DNA methylation and non-coding RNA expression, on transcriptional modulation in nociceptive pathways during the development of tissue injury-associated pain. We assess the pre-clinical data and their translational implication and evaluate the potential of controlling DNA methylation and non-coding RNA expression as novel analgesic approaches and/or biomarkers of persistent pain.
Torres Perez J, Irfan J, Febrianto MR, et al., 2021, Histone post-translational modification as potential therapeutic targets for pain management, Trends in Pharmacological Sciences, Vol: 42, Pages: 897-911, ISSN: 0165-6147
Effective pharmacological management of pain associated with tissue unmet medical need. Transcriptional modifications in nociceptive pathways are pivotal for the development and the maintenance of pain associated with tissue damage. Accumulating evidence has shown the importance of the epigenetic control of transcription within nociceptive pathways via histone post-translational modifications (PTMs). Hence, histone PTMs could be targets for novel effective analgesics. Here, we discuss the current understanding of histone PTMs in the modulation of gene expression affecting nociception and pain phenotypes following tissue injury. We also provide a critical view of the translational implications of preclinical models and discuss opportunities and challenges of targeting histone PTMs for relieving pain in clinically relevant tissue injuries.
Cuddihy J, Wu G, Ho L, et al., 2021, Lactate dehydrogenase activity staining demonstrates time-dependent immune cell infiltration in human ex-vivo burn-injured skin, Scientific Reports, Vol: 11, Pages: 1-12, ISSN: 2045-2322
Burn injuries constitute one of the most serious accidental injuries. Increased metabolic rate is a hallmark feature of burn injury. Visualising lactate dehydrogenase (LDH) activity has been previously used to identify metabolic activity differences, hence cell viability and burn depth in burn skin. LDH activity was visualised in injured and uninjured skin from 38 sub-acute burn patients. LDH activity aided the identification of spatially correlating immunocompetent cells in a sub-group of six patients. Desorption Electrospray Ionisation Mass Spectrometry Imaging (DESI MSI) was used to describe relative lactate and pyruvate abundance in burned and uninjured tissue. LDH activity was significantly increased in the middle and deep regions of burnt skin compared with superficial areas in burnt skin and uninjured tissue and positively correlated with post-burn time. Regions of increased LDH activity showed high pyruvate and low lactate abundance when examined with DESI-MSI. Areas of increased LDH activity exhibited cellular infiltration, including CD3 + and CD4 + T-lymphocytes and CD68 + macrophages. Our data demonstrate a steady increase in functional LDH activity in sub-acute burn wounds linked to cellular infiltration. The cell types associated are related to tissue restructuring and inflammation. This region in burn wounds is likely the focus of dysregulated inflammation and hypermetabolism.
Sousa Valente J, Alavi J, Barde S, et al., 2021, (-)-Englerin-A has analgesic and anti-inflammatory effects independent of TRPC4 and 5, International Journal of Molecular Sciences, Vol: 22, ISSN: 1422-0067
Recently, we found that the deletion of TRPC5 leads to increased inflammation and pain-related behaviour in two animal models of arthritis. (-)-Englerin A (EA), an extract from the East African plant Phyllanthus engleri has been identified as a TRPC4/5 agonist. Here, we studied whether or not EA has any anti-inflammatory and analgesic properties via TRPC4/5 in the carrageenan model of inflammation. We found that EA treatment in CD1 mice inhibited thermal hyperalgesia and mechanical allodynia in a dose-dependent manner. Furthermore, EA significantly reduced the volume of carrageenan-induced paw oedema and the mass of the treated paws. Additionally, in dorsal root ganglion (DRG) neurons cultured from WT 129S1/SvIm mice, EA induced a dose-dependent cobalt uptake that was surprisingly preserved in cultured DRG neurons from 129S1/SvIm TRPC5 KO mice. Likewise, EA-induced anti-inflammatory and analgesic effects were preserved in the carrageenan model in animals lacking TRPC5 expression or in mice treated with TRPC4/5 antagonist ML204.This study demonstrates that while EA activates a sub-population of DRG neurons, it induces a novel TRPC4/5-independent analgesic and anti-inflammatory effect in vivo. Future studies are needed to elucidate the molecular and cellular mechanisms underlying EA’s anti-inflammatory and analgesic effects.
Nagy I, Varga A, Meszar Z, et al., 2021, Spinal excitatory dynorphinergic interneurons contribute to burn injury-induced nociception mediated by phosphorylated histone 3 at serine 10 in rodents, International Journal of Molecular Sciences, Vol: 22, Pages: 1-28, ISSN: 1422-0067
The phosphorylation of serine 10 in histone 3 (p-S10H3) has recently been demonstrated to participate in spinal nociceptive processing. However, superficial dorsal horn (SDH) neurons involved in p-S10H3-mediated nociception have not been fully characterized. In the present work, we combined immunohistochemistry, in situ hybridization with the retrograde labeling of projection neurons to reveal the subset of dorsal horn neurons presenting an elevated level of p-S10H3 in response to noxious heat (60 °C), causing burn injury. Projection neurons only represented a small percentage (5%) of p-S10H3-positive cells, while the greater part of them belonged to excitatory SDH interneurons. The combined immunolabeling of p-S10H3 with markers of already established interneuronal classes of the SDH revealed that the largest subset of neurons with burn injury-induced p-S10H3 expression was dynorphin immunopositive in mice. Furthermore, the majority of p-S10H3-expressing dynorphinergic neurons proved to be excitatory, as they lacked Pax-2 and showed Lmx1b-immunopositivity. Thus, we showed that neurochemically heterogeneous SDH neurons exhibit the upregulation of p-S10H3 shortly after noxious heat-induced burn injury and consequential tissue damage, and that a dedicated subset of excitatory dynorphinergic neurons is likely a key player in the development of central sensitization via the p-S10H3 mediated pathway.
Nagy I, Li T, Wang T, et al., 2021, TRPV1 feed-forward sensitisation depends on COX2 upregulation in primary sensory neurons, Scientific Reports, Vol: 11, ISSN: 2045-2322
Increased activity and excitability (sensitisation) of a series of molecules including the transient receptor potential ion channel, vanilloid subfamily, member 1 (TRPV1) in pain-sensing (nociceptive) primary sensory neurons are pivotal for developing pathological pain experiences in tissue injuries. TRPV1 sensitisation is induced and maintained by two major mechanisms; post-translational and transcriptional changes in TRPV1 induced by inflammatory mediators produced and accumulated in injured tissues, and TRPV1 activation-induced feed-forward signalling. The latter mechanism includes synthesis of TRPV1 agonists within minutes, and upregulation of various receptors functionally linked to TRPV1 within a few hours, in nociceptive primary sensory neurons. Here, we report that a novel mechanism, which contributes to TRPV1 activation-induced TRPV1-sensitisation within ~ 30 min in at least ~ 30% of TRPV1-expressing cultured murine primary sensory neurons, is mediated through upregulation in cyclooxygenase 2 (COX2) expression and increased synthesis of a series of COX2 products. These findings highlight the importance of feed-forward signalling in sensitisation, and the value of inhibiting COX2 activity to control pain, in nociceptive primary sensory neurons in tissue injuries.
Mirzaei N, Mota B, Birch A, et al., 2021, Imidazoline ligand BU224 reverses cognitive deficits, reduces microgliosis and enhances synaptic connectivity in a mouse model of Alzheimer’s disease, British Journal of Pharmacology, Vol: 178, Pages: 654-671, ISSN: 0007-1188
Background and PurposeActivation of type‐2 Imidazoline receptors has been shown to exhibit neuroprotective properties including anti‐apoptotic and anti‐inflammatory effects, suggesting a potential therapeutic value in Alzheimer's disease (AD). Here, we explored the effects of the Imidazoline‐2 ligand BU224 in a model of amyloidosis.Experimental approach6‐month‐old female transgenic 5XFAD and wild‐type (WT) mice were treated intraperitoneally with 5 mg.kg‐1 BU224 or vehicle twice a day for 10 days. Behavioural tests were performed for cognitive functions and neuropathological changes were investigated by immunohistochemistry, Western blot, ELISA and qPCR. Effects of BU224 on APP processing, spine density and calcium imaging were analysed in brain organotypic cultures and N2a cells.Key ResultsBU224 treatment attenuated spatial and perirhinal cortex‐dependent recognition memory deficits in 5XFAD mice. Fear conditioning testing revealed that BU224 also improved both associative learning and hippocampal‐ and amygdala‐dependent memory in transgenic but not in WT mice. In the brain, BU224 reduced levels of the microglial marker Iba1 and pro‐inflammatory cytokines IL‐1β and TNFα, and increased the expression of astrocytic marker GFAP in 5XFAD mice. These beneficial effects were not associated with changes in amyloid pathology, neuronal apoptosis, mitochondrial density, oxidative stress or autophagy markers. Interestingly, ex vivo and in vitro studies suggested that BU224 treatment increased the size of dendritic spines and induced a 3‐fold reduction in Aβ‐induced functional changes in NMDA receptors.Conclusions and implicationsOur data indicate that sub‐chronic treatment with BU224 improves memory and reduces inflammation in transgenic AD mice, at stages when animals display severe pathology.
Valente JDS, Alawi K, Bahrde S, et al., 2021, Studying the anti-inflammatory and analgesic effect of Transient Receptor Potential Canonical 5 (TRPC5) agonist (-)-Englerin-A, 2000 Meeting of the British-Pharmacological-Society (PHARMACOLOGY), Publisher: WILEY, Pages: 450-451, ISSN: 0007-1188
Santos GG, Li R, Ng M, et al., 2020, CB1 receptor-dependent TRPV1 desensitisation contributes to the analgesic effect of dipyrone in sensitised primary sensory neurons, British Journal of Pharmacology, ISSN: 0007-1188
Li T, Wang G, Chin Hui VC, et al., 2020, TRPV1 feed-forward sensitisation depends on COX2 upregulation in primary sensory neurons, Publisher: Cold Spring Harbor Laboratory
<jats:title>ABSTRACT</jats:title><jats:p>Increased activity and excitability (sensitisation) of a series of molecules including the transient receptor potential ion channel, vanilloid subfamily, member 1 (TRPV1) in pain-sensing (nociceptive) primary sensory neurons are pivotal for developing pathological pain experiences in tissue injuries. TRPV1 sensitisation is induced and maintained by two major mechanisms; post-translational and transcriptional changes in TRPV1 induced by inflammatory mediators produced and accumulated in injured tissues, and TRPV1 activation-induced feed-forward signalling. The latter mechanism includes synthesis of TRPV1 agonists within minutes, and upregulation of various receptors functionally linked to TRPV1 within a few hours, in nociceptive primary sensory neurons. Here, we report that a novel mechanism, which contributes to TRPV1 activation-induced TRPV1-sensitisation within ∼30 minutes in at least ∼30% of TRPV1-expressing cultured murine primary sensory neurons, is mediated through upregulation in cyclooxygenase 2 (COX2) expression and increased synthesis of a series of COX2 products. These findings highlight the importance of feed-forward signalling in sensitisation, and the value of inhibiting COX2 activity to control pain, in nociceptive primary sensory neurons in tissue injuries.</jats:p>
La Montanara P, Hervera A, Baltussen L, et al., 2020, Cyclin-dependent-like kinase 5 is required for pain signaling in human sensory neurons and mouse models, Science Translational Medicine, Vol: 12, Pages: 1-11, ISSN: 1946-6234
Cyclin-dependent-like kinase 5 (Cdkl5) gene mutations lead to an X-linked disorder that is characterized by infantile epileptic encephalopathy, developmental delay and hypotonia. However, we found that a substantial percentage of these patients also report a previously unrecognised anamnestic deficiency in pain perception. Consistent with a role in nociception, we discovered that Cdkl5 is expressed selectively in nociceptive dorsal root ganglia (DRG) neurons in mice and in iPS-derived human nociceptors. CDKL5 deficient mice display defective epidermal innervation and conditional deletion of Cdkl5 in DRG sensory neurons significantly impairs nociception, phenocopying CDKL5 deficiency disorder in patients. Mechanistically, Cdkl5 interacts with CaMKIIα to control outgrowth as well as TRPV1-dependent signalling, which are disrupted in both Cdkl5 mutant murine DRG and human iPS-derived nociceptors. Together, these findings unveil a previously unrecognized role for Cdkl5 in nociception, proposing an original regulatory mechanism for pain perception with implications for future therapeutics in CDKL5 deficiency disorder.
Friston D, Junttila S, Borges Paes Lemes J, et al., 2020, Leptin and fractalkine: novel subcutaneous cytokines in burn injury, Disease Models and Mechanisms, Vol: 13, ISSN: 1754-8403
Burn injury is a pathology underpinned by progressive and aberrant inflammation. It is a major clinical challenge to survival and quality of life. While burn injury’s complex local and disseminating pathological processes ultimately stem from local tissue damage, to date relatively few studies have attempted to characterise the local inflammatory mediator profile. Here, cytokine content and associated transcriptional changes were measured in rat skin for three hours immediately following induction of a scald-type (60oC, 2 minutes) burn injury model. Leptin (p = 0.0002) and fractalkine (p = 0.0478) concentrations were significantly elevated post-burn above pre-burn and control site values, coinciding with the development of burn site oedema and differential expression of leptin mRNA (p = 0.0004). Further, gene sequencing enrichment analysis indicated cytokine-cytokine receptor interaction (p = 1.45x10-6). Subsequent behavioural studies demonstrated that, following subcutaneous injection into the dorsum of the paw, both leptin and fractalkine induced mechanical allodynia, heat hyperalgesia and the recruitment of macrophages. This is the first report of leptin’s elevation specifically at the burn site and the first report of fractalkine’s elevation in any tissue post-burn which, together with the functional findings, calls for exploration of the influence of these cytokines on pain, inflammation and burn wound progression. Additionally targeting these signalling molecules represents a therapeutic potential as early formative mediators of these pathological processes.
Friston D, Junttila S, Lemes JBP, et al., 2020, Leptin and fractalkine: Novel subcutaneous cytokines in burn injury., Dis Model Mech
Burn injury is a pathology underpinned by progressive and aberrant inflammation. It is a major clinical challenge to survival and quality of life. While burn injury's complex local and disseminating pathological processes ultimately stem from local tissue damage, to date relatively few studies have attempted to characterise the local inflammatory mediator profile. Here, cytokine content and associated transcriptional changes were measured in rat skin for three hours immediately following induction of a scald-type (60°C, 2 minutes) burn injury model. Leptin (p=0.0002) and fractalkine (p=0.0478) concentrations were significantly elevated post-burn above pre-burn and control site values, coinciding with the development of burn site oedema and differential expression of leptin mRNA (p=0.0004). Further, gene sequencing enrichment analysis indicated cytokine-cytokine receptor interaction (p=1.45x10-6). Subsequent behavioural studies demonstrated that, following subcutaneous injection into the dorsum of the paw, both leptin and fractalkine induced mechanical allodynia, heat hyperalgesia and the recruitment of macrophages. This is the first report of leptin's elevation specifically at the burn site and the first report of fractalkine's elevation in any tissue post-burn which, together with the functional findings, calls for exploration of the influence of these cytokines on pain, inflammation and burn wound progression. Additionally targeting these signalling molecules represents a therapeutic potential as early formative mediators of these pathological processes.
Charrua A, Matos R, Oliviera R, et al., 2019, Fatty Acid Amide Hydrolase inhibition normalises bladder function and reduces pain through normalising the anandamide/palmitoylethanolamine ratio in the inflamed bladder of rats, Naunyn-Schmiedeberg's Archives of Pharmacology, ISSN: 0028-1298
Gram DX, Fribo J, Nagy I, et al., 2019, TRPV1 antagonists as novel anti-diabetic agents: regulation of oral glucose tolerance and insulin secretion through reduction of low-grade inflammation?, Medical Sciences, Vol: 7, Pages: 1-14
With a global prevalence among adults over 18 years of age approaching 9%, Type 2 diabetes mellitus (T2DM) has reached pandemic proportions and represents a major unmet medical need. To date, no disease modifying treatment is available for T2DM patients. Accumulating evidence suggest that the sensory nervous system is involved in the progression of T2DM by maintaining low-grade inflammation via the vanilloid (capsaicin) receptor, Transient Receptor Potential Vanilloid-1 (TRPV1). In this study, we tested the hypothesis that TRPV1 is directly involved in glucose homeostasis in rodents. TRPV1 receptor knockout mice (Trpv1−/−) and their wild-type littermates were kept on high-fat diet for 15 weeks. Moreover, Zucker obese rats were given the small molecule TRPV1 antagonist, N-(4-Tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl)tetrahydropyrazine-1(2H)-carbox-amide (BCTC), per os twice-a-day or vehicle for eight days. Oral glucose tolerance and glucose-stimulated insulin secretion was improved by both genetic inactivation (Trpv1−/− mice) and pharmacological blockade (BCTC) of TRPV1. In the obese rat, the improved glucose tolerance was accompanied by a reduction in inflammatory markers in the mesenteric fat, suggesting that blockade of low-grade inflammation contributes to the positive effect of TRPV1 antagonism on glucose metabolism. We propose that TRPV1 could be a promising therapeutic target in T2DM by improving glucose intolerance and correcting dysfunctional insulin secretion.</jats:p>
La Montanara P, Hervera A, Baltussen L, et al., 2019, Cyclin-dependent-like kinase 5 is required for pain signalling in both human neurons and mouse models, Publisher: bioRxiv
Abstract Cyclin-dependent-like kinase 5 ( Cdkl5) gene mutations lead to an X-linked disorder that is characterized by infantile epileptic encephalopathy, developmental delay and hypotonia. However, we found that a substantial percentage of these patients also report a previously unrecognised anamnestic deficiency in pain perception. Consistent with a role in nociception, we discovered that Cdkl5 is expressed selectively in nociceptive dorsal root ganglia (DRG) neurons in mice and in iPS-derived human nociceptors. CDKL5 deficient mice display defective epidermal innervation and conditional deletion of Cdkl5 in DRG sensory neurons significantly impairs nociception, phenocopying CDKL5 deficiency disorder in patients. Mechanistically, Cdkl5 interacts with CaMKIIα to control outgrowth as well as TRPV1-dependent signalling, which are disrupted in both Cdkl5 mutant murine DRG and human iPS-derived nociceptors. Together, these findings unveil a previously unrecognized role for Cdkl5 in nociception, proposing an original regulatory mechanism for pain perception with implications for future therapeutics in CDKL5 deficiency disorder. One Sentence Summary Cyclin-dependent-like kinase 5 (Cdkl5) controls nociception in patients and murine models of Cdkl5 deficiency disorder via CaMKII-dependent mechanisms
Friston D, Laycock H, Nagy I, et al., 2019, Microdialysis workflow for metabotyping superficial pathologies: application to burn injury, Analytical Chemistry, Vol: 91, Pages: 6541-6548, ISSN: 0003-2700
Burn injury can be a devastating traumatic injury, with long-term personal and social implications for the patient. The many complex local and disseminating pathological processes underlying burn injury's clinical challenges are orchestrated from the site of injury and develop over time, yet few studies of the molecular basis of these mechanisms specifically explore the local signaling environment. Those that do are typically destructive in nature and preclude the collection of longitudinal temporal data. Burn injury therefore exemplifies a superficial temporally dynamic pathology for which experimental sampling typically prioritizes either specificity to the local burn site or continuous collection from circulation. Here, we present an exploratory approach to the targeted elucidation of complex, local, acutely temporally dynamic interstitia through its application to burn injury. Subcutaneous microdialysis is coupled with ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) analysis, permitting the application of high-throughput metabolomic profiling to samples collected both continuously and specifically from the burn site. We demonstrate this workflow's high yield of burn-altered metabolites including the complete structural elucidation of niacinamide and uric acid, two compounds potentially involved in the pathology of burn injury. Further understanding the metabolic changes induced by burn injury will help to guide therapeutic intervention in the future. This approach is equally applicable to the analysis of other tissues and pathological conditions, so it may further improve our understanding of the metabolic changes underlying a wide variety of pathological processes.
Nagy I, Lazar BA, Jancso G, et al., 2018, Insulin confers differing effects on neurite outgrowth in separate populations of cultured dorsal root ganglion neurons: the role of the insulin receptor, Frontiers in Neuroscience, Vol: 12, ISSN: 1662-4548
Apart from its pivotal role in the regulation of carbohydrate metabolism, insulin exerts important neurotrophic and neuromodulator effects on dorsal root ganglion (DRG) neurons. The neurite outgrowth-promoting effect is one of the salient features of insulin’s action on cultured DRG neurons. Although it has been established that a significant population of DRG neurons express the insulin receptor (InsR), the significance of InsR expression and the chemical phenotype of DRG neurons in relation to the neurite outgrowth-promoting effect of insulin has not been studied. Therefore, in this study by using immunohistochemical and quantitative stereological methods we evaluated the effect of insulin on neurite outgrowth of DRG neurons of different chemical phenotypes which express or lack the InsR. Insulin, at a concentration of 10 nM, significantly increased total neurite length, the length of the longest neurite and the number of branch points of cultured DRG neurons as compared to neurons cultured in control medium or in the presence of 1 μM insulin. In both the control and the insulin exposed cultures, ∼43% of neurons displayed InsR-immunoreactivity. The proportions of transient receptor potential vanilloid type 1 receptor (TRPV1)-immunoreactive (IR), calcitonin gene-related peptide (CGRP)-IR and Bandeiraea simplicifolia isolectin B4 (IB4)-binding neurons amounted to ∼61%, ∼57%, and ∼31% of DRG neurons IR for the InsR. Of the IB4-positive population only neurons expressing the InsR were responsive to insulin. In contrast, TRPV1-IR nociceptive and CGRP-IR peptidergic neurons showed increased tendency for neurite outgrowth which was further enhanced by insulin. However, the responsiveness of DRG neurons expressing the InsR was superior to populations of DRG neurons which lack this receptor. The findings also revealed that besides the expression of the InsR, inherent properties of peptidergic, but not non-peptidergic nociceptive neurons may also si
Nagy I, Bence L, Gabor J, et al., 2018, The Insulin Receptor is Differentially Expressed in Somatic and Visceral Primary Sensory Neurons, Cell and Tissue Research, ISSN: 0302-766X
Nerandzic V, Mrozkova P, Adamek P, et al., 2018, Peripheral inflammation alters N-arachidonoylphosphatidylethanolamine (20:4-NAPE) induced modulation of nociceptive spinal cord synaptic transmiss, British Journal of Pharmacology, Vol: 175, Pages: 2322-2336, ISSN: 1476-5381
Background and Purpose Endocannabinoids play an important role in modulating spinal nociceptive signalling, crucial for the development of pain. The cannabinoid receptor 1 (CB1) and the transient receptor potential cation channel subfamily V member 1 (TRPV1) are both activated by the endocannabinoid anandamide that is a product of biosynthesis from the endogenous lipid precursor N1arachidonoylphosphatidylethanolamine (20:41NAPE). Here we are first to report CB1 receptor1 and TRPV11mediated effects of 20:41NAPE application on spinal synaptic transmission in control and inflammatory conditions. Experimental Approach Spontaneous (sEPSCs) and dorsal root stimulation1evoked (eEPSCs) excitatory postsynaptic currents from superficial dorsal horn neurons in rat spinal cord slices were assessed. Peripheral inflammation was induced by carrageenan. Anandamide concentration was assessed by mass spectrometry. Key Results Application of 20:41NAPE increased anandamide concentration in vitro. 20:41NAPE (20 μM) decreased sEPSCs frequency and eEPSCs amplitude in control and inflammatory conditions. The inhibitory effect of 20:41NAPE was sensitive to CB1 antagonist PF514273 (0.2 μM) in both conditions, but to the TRPV1 antagonist SB366791 (10 μM) only after inflammation. After inflammation 20:41NAPE increased sEPSCs frequency in the presence of PF514273 and this increase was blocked by SB366791. Conclusions and Implications While 20:41NAPE treatment produced an inhibitory effect on excitatory synaptic transmission in both naive and inflammatory conditions, peripheral inflammation altered the underlying mechanisms. Our data indicate that 20:41NAPE application induced mainly CB1 receptor1mediated inhibitory effects in naive animals while TRPV11mediated mechanisms were also involved after inflammation. Increasing anandamide levels for analgesic purposes by applying substrate for its local synthesis may be superior to systemic anand
Nagy I, Bence L, Gabor J, et al., 2018, The Insulin Receptor Is Colocalized With the TRPV1 Nociceptive Ion Channel and Neuropeptides in Pancreatic Spinal and Vagal Primary Sensory Neurons, Pancreas, Vol: 47, Pages: 110-115, ISSN: 0885-3177
Objectives Recent observations demonstrated the expression of the insulin receptor (InsR) and its functional interaction with the transient receptor potential vanilloid type 1 receptor (TRPV1) in sensory ganglion neurons. Because sensory nerves are implicated in pancreatic inflammatory processes, we studied the colocalization of the InsR with TRPV1 and proinflammatory neuropeptides in spinal and vagal pancreatic afferent neurons.Methods Immunohistochemistry and quantitative morphometry were used to analyze the expression of TRPV1, InsR, substance P (SP), and calcitonin gene-related peptide (CGRP) in retrogradely labeled pancreatic dorsal root ganglion (DRG) and nodose ganglion (NG) neurons.Results The proportions of retrogradely labeled pancreatic TRPV1-, InsR-, SP-, and CGRP-immunoreactive neurons amounted to 68%, 48%, 33%, and 54% in DRGs and 64%, 49%, 40%, and 25% in the NGs. Of the labeled DRG and NG neurons, 23% and 35% showed both TRPV1 and InsR immunoreactivity. Colocalization of the InsR with SP or CGRP was demonstrated in 14% and 28% of pancreatic DRG and 24% and 8% of pancreatic NG neurons.Conclusions The present findings provide morphological basis for possible functional interactions among the nociceptive ion channel TRPV1, the InsR, and the proinflammatory neuropeptides SP and CGRP expressed by pancreatic DRG and NG neurons.
Nagy I, Charrua A, Matos R, et al., 2017, FAAH Inhibitor Improves Function of Inflamed Bladders by Modulation of Anandamide and Palmitoylethanolamide, Acta Urologica Portuguesa, Vol: 34, Pages: 21-28, ISSN: 2341-4022
Introduction: We aim to study the effect of fatty acid amide hydrolase (FAAH) blockade on bladder hyperactivity and on fatty acid amides levels during cystitis.Material and Methods: Cystitis was induced in female Wistar rats using 5 mg/mL lipopolysaccharide (LPS). Control group were intravesical instilled with saline. LPS and control groups received intravenously (caudal vein) during cystometry: URB 937 (URB; FAAH antagonist) in doses of 0.007, 0.07, 0.7 and 7 mg/kg (cumulative, with 10 minutes interval). Using the maximal effective dose of URB (0.7 mg/kg, see below) animals received 10 uM MJ15 (CB1 receptor antagonist) or 0.3 mg SR144528 /kg (SR; CB2 receptor antagonist). At dose of 7 mg/kg, animals receive 1.4 μg SB366791/kg (SB; TRPV1 antagonist). Control and inflamed (without and with 0.7 and 7 mg/kg URB) group were euthanized and the bladder was harvested for the determination of anandamide (AEA) and palmitoylethanolamide (PEA) by mass spectrometry.Results: Frequency of control was not changed by URB treatment at any dose. LPS increase bladder frequency. 0.007 mg and 0.07 mg URB decrease bladder frequency of LPS-inflamed rats. 0.7 URB reversed LPS-induced bladder hyperactivity. At 7 mg, URB was unable to reverse or reduce LPS-induced bladder hyperactivity. The administration of CB1, CB2 and TRPV1 antagonists did not change the frequency of voiding contractions of naïve animals. CB1 antagonist reversed the effect of 0.7 URB while TRPV1 antagonist reduced the effect of 7 URB. AEA levels increase during inflammation. Treating LPS-inflamed animals with 0.7 mg URB brought AEA levels to control levels. Treating LPS-inflamed animals with 7 mg URB did not change AEA levels, compared to LPS-inflamed animals. PEA levels decrease during inflammation. Treating LPS-inflamed animals with 0.7 mg URB brought AEA levels to control levels. Treating LPS-inflamed animals with 7 mg URB, decreased PEA levels to values similar to the ones observed in LPS- -inflamed animals.Co
Nagy I, Torres-Perez JV, Adamek P, et al., 2017, The NAv1.7 blocker protoxin II reduces burn injury-induced spinal nociceptive processing, Journal of Molecular Medicine, Vol: 96, Pages: 75-84, ISSN: 0946-2716
Controlling pain in burn-injured patients poses a major clinical challenge. Recent findings suggest that reducing the activity of the voltage-gated sodium channel Nav1.7 in primary sensory neurons could provide improved pain control in burn-injured patients. Here, we report that partial thickness scalding-type burn injury on the rat paw upregulates Nav1.7 expression in primary sensory neurons 3 h following injury. The injury also induces upregulation in phosphorylated cyclic adenosine monophosphate response element-binding protein (p-CREB), a marker for nociceptive activation in primary sensory neurons. The upregulation in p-CREB occurs mainly in Nav1.7-immunopositive neurons and exhibits a peak at 5 min and, following a decline at 30 min, a gradual increase from 1 h post-injury. The Nav1.7 blocker protoxin II (ProTxII) or morphine injected intraperitoneally 15 min before or after the injury significantly reduces burn injury-induced spinal upregulation in phosphorylated serine 10 in histone H3 and phosphorylated extracellular signal-regulated kinase 1/2, which are both markers for spinal nociceptive processing. Further, ProTxII significantly reduces the frequency of spontaneous excitatory post-synaptic currents in spinal dorsal horn neurons following burn injury. Together, these findings indicate that using Nav1.7 blockers should be considered to control pain in burn injury.
Nagy I, Varga A, Vicente Torres Perez J, 2017, Development of analgesics: a little help from mitogen and stress-activated kinases 1 and 2, Journal of Pharmaceutical Research and Drug Design, Vol: 1
Nagy I, Suosa-Valente J, Varga A, et al., 2017, Inflammation of peripheral tissues and injury to peripheral nerves induce diferring effects in the expression of the calcium-sensitive anandamide synthesising enzyme and related molecules in ratprimary sensory neuron, Journal of Comparative Neurology, Vol: 525, Pages: 1778-1796, ISSN: 1096-9861
Elevation of intracellular Ca2+ concentration induces the synthesis of N0arachydonoylethanolamine (anandamide) in a sub0population of primary sensory neurons. N0acylphosphatidylethanolamine phospholipase D (NAPE0PLD) is the only known enzyme, which synthesises anandamide in a Ca2+0dependent manner. NAPE0PLD mRNA, as well as anandamide's main targets, the excitatory transient receptor potential vanilloid type 1 ion channel (TRPV1) and the inhibitory cannabinoid type 1 (CB1) receptor and the main anandamide0hydrolysing enzyme fatty acid amide hydrolase (FAAH) are all expressed by sub0populations of nociceptive primary sensory neurons. Thus, NAPE0PLD, TRPV1, the CB1 receptor and FAAH could form an autocrine signalling system, which could shape the activity of a major sub0population of nociceptive primary sensory neurons, hence contribute to the development of pain. While the expression patterns of TRPV1, the CB1 receptor and FAAH have been comprehensively elucidated, little is known about NAPE0PLD expression in primary sensory neurons under physiological and pathological conditions. We report that NAPE0PLD is expressed by about a third of primary sensory neurons, the overwhelming majority of which also express nociceptive markers as well as the CB1 receptor, TRPV1 and FAAH. Inflammation of peripheral tissues and injury to peripheral nerves induce differing but concerted changes in the expression pattern of NAPE0PLD, the CB1 receptor, TRPV1 and FAAH. Together these data indicate the existence of the anatomical basis for an autocrine signalling system, in a major proportion of nociceptive primary sensory neurons, and that alterations in that autocrine signalling by peripheral pathologies could contribute to the development of both inflammatory and neuropathic pain.
Torres-Perez JV, Santha P, Varga A, et al., 2017, Phosphorylated histone 3 at serine 10 identifies activated spinal neurons and contributes to the development of tissue injury-associated pain, Scientific Reports, Vol: 7, ISSN: 2045-2322
Transcriptional changes in superficial spinal dorsal horn neurons (SSDHN) are essential in the development and maintenance of prolonged pain. Epigenetic mechanisms including post-translational modifications in histones are pivotal in regulating transcription. Here, we report that phosphorylation of serine 10 (S10) in histone 3 (H3) specifically occurs in a group of rat SSDHN following the activation of nociceptive primary sensory neurons by burn injury, capsaicin application or sustained electrical activation of nociceptive primary sensory nerve fibres. In contrast, brief thermal or mechanical nociceptive stimuli, which fail to induce tissue injury or inflammation, do not produce the same effect. Blocking N-methyl-D-aspartate receptors or activation of extracellular signal-regulated kinases 1 and 2, or blocking or deleting the mitogen- and stress-activated kinases 1 and 2 (MSK1/2), which phosphorylate S10 in H3, inhibit up-regulation in phosphorylated S10 in H3 (p-S10H3) as well as fos transcription, a down-stream effect of p-S10H3. Deleting MSK1/2 also inhibits the development of carrageenan-induced inflammatory heat hyperalgesia in mice. We propose that p-S10H3 is a novel marker for nociceptive processing in SSDHN with high relevance to transcriptional changes and the development of prolonged pain.
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