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Sample records for mediate mechanical hyperalgesia

  1. Mechanisms mediating nitroglycerin-induced delayed-onset hyperalgesia in the rat.

    PubMed

    Ferrari, L F; Levine, J D; Green, P G

    2016-03-11

    Nitroglycerin (glycerol trinitrate, GTN) induces headache in migraineurs, an effect that has been used both diagnostically and in the study of the pathophysiology of this neurovascular pain syndrome. An important feature of this headache is a delay from the administration of GTN to headache onset that, because of GTN's very rapid metabolism, cannot be due to its pharmacokinetic profile. It has recently been suggested that activation of perivascular mast cells, which has been implicated in the pathophysiology of migraine, may contribute to this delay. We reported that hyperalgesia induced by intradermal GTN has a delay to onset of ∼ 30 min in male and ∼ 45 min in female rats. This hyperalgesia was greater in females, was prevented by pretreatment with the anti-migraine drug, sumatriptan, as well as by chronic pretreatment with the mast cell degranulator, compound 48/80. The acute administration of GTN and compound 48/80 both induced hyperalgesia that was prevented by pretreatment with octoxynol-9, which attenuates endothelial function, suggesting that GTN and mast cell-mediated hyperalgesia are endothelial cell-dependent. Furthermore, A-317491, a P2X3 antagonist, which inhibits endothelial cell-dependent hyperalgesia, also prevents GTN and mast cell-mediated hyperalgesia. We conclude that delayed-onset mechanical hyperalgesia induced by GTN is mediated by activation of mast cells, which in turn release mediators that stimulate endothelial cells to release ATP, to act on P2X3, a ligand-gated ion channel, in perivascular nociceptors. A role of the mast and endothelial cell in GTN-induced hyperalgesia suggests potential novel risk factors and targets for the treatment of migraine. PMID:26779834

  2. Serotonin Receptor 2B Mediates Mechanical Hyperalgesia by Regulating Transient Receptor Potential Vanilloid 1.

    PubMed

    Su, Yeu-Shiuan; Chiu, Yuan-Yi; Lin, Shih-Yuan; Chen, Chih-Cheng; Sun, Wei-Hsin

    2016-05-01

    Serotonin [5-hydroxytryptamine (5-HT)], an inflammatory mediator, contributes to inflammatory pain. The presence of multiple 5-HT subtype receptors on peripheral and central nociceptors complicates the role of 5-HT in pain. Previously, we found that 5-HT2B/2C antagonist could block 5-HT-induced mechanical hyperalgesia. However, the types of neurons or circuits underlying this effect remained unsolved. Here, we demonstrate that the Gq/11-phospholipase Cβ-protein kinase Cε (PKCε) pathway mediated by 5-HT2B is involved in 5-HT-induced mechanical hyperalgesia in mice. Administration of a transient receptor potential vanilloid 1 (TRPV1) antagonist inhibited the 5-HT-induced mechanical hyperalgesia. 5-HT injection enhanced 5-HT- and capsaicin-evoked calcium signals specifically in isolectin B4 (IB4)-negative neurons; signals were inhibited by a 5-HT2B/2C antagonist and PKCε blocker. Thus, 5-HT2B mediates 5-HT-induced mechanical hyperalgesia by regulating TRPV1 function. PMID:26635025

  3. TRPC1 and TRPC6 channels cooperate with TRPV4 to mediate mechanical hyperalgesia and nociceptor sensitization

    PubMed Central

    Alessandri-Haber, Nicole; Dina, Olayinka A.; Chen, Xiaoje; Levine, Jon D.

    2009-01-01

    The transient receptor potential vanilloid 4 (TRPV4) contributes to mechanical hyperalgesia of diverse etiologies, presumably as part of a mechanoreceptor signaling complex (Alessandri-Haber et al., 2008). To investigate the hypothesis that a functional interaction between TRPV4 and stretch-activated ion channels (SACs) is involved in this mechanical transduction mechanism, we used a selective SACs inhibitor, GsMTx-4. Intradermal injection of GsMTx-4 in the rat hind paw reversed the mechanical hyperalgesia induced by intradermal injection of inflammatory mediators. In vivo single fiber recordings showed that GsMTx-4 reversed inflammatory mediator-induced decrease in mechanical threshold in half of sensitized C-fibers. Furthermore, GsMTx-4 reduced hyperalgesia to both mechanical and hypotonic stimuli in different models of inflammatory and neuropathic pain while it had no effect on baseline mechanical nociceptive thresholds. TRPC1 and TRPC6, two GsMTx-4-sensitive SACs are expressed in dorsal root ganglion neurons (DRG). Single-cell RT-PCR showed that messenger RNAs for TRPV4, TRPC1 and TRPC6 are frequently co-expressed in DRG neurons. Spinal intrathecal administration of oligodeoxynucleotides antisense to TRPC1 and TRPC6, like that to TRPV4, reversed the hyperalgesia to mechanical and hypotonic stimuli induced by inflammatory mediators without affecting baseline mechanical nociceptive threshold. However, antisense to TRPC6, but not to TRPC1, reversed the mechanical hyperalgesia induced by a thermal injury or the TRPV4 selective agonist 4α-PDD. We conclude that TRPC1 and TRPC6 channels cooperate with TRPV4 channels to mediate mechanical hyperalgesia and primary afferent nociceptor sensitization although they may have distinctive roles. PMID:19439599

  4. ATP release mechanisms of endothelial cell-mediated stimulus-dependent hyperalgesia

    PubMed Central

    Joseph, Elizabeth K.; Green, Paul G.; Levine, Jon D.

    2014-01-01

    Endothelin-1 acts on endothelial cells to enhance mechanical stimulation-induced release of ATP, which in turn can act on sensory neurons innervating blood vessels to contribute to vascular pain, a phenomenon we have referred to as stimulus-dependent hyperalgesia (SDH). In the present study we evaluated the role of the major classes of ATP release mechanisms to SDH: vesicular exocytosis, plasma membrane associated ATP synthase, ATP-Binding Cassette (ABC) transporters, and ion channels. Inhibitors of vesicular exocytosis (i.e., monensin, brefeldin A and bafilomycin), plasma membrane associated ATPase (i.e., oligomycin and pigment epithelium-derived factor-derived peptide 34-mer) and connexin ion channels (carbenoxolone and flufenamic acid), but not ABC transporters (i.e., dipyridamole, nicardipine or CFTRinh-172) attenuated stimulus-dependent hyperalgesia. These studies support a role of ATP in SDH, and suggest novel targets for the treatment of vascular pain syndromes. PMID:24793242

  5. SPINAL CORD MECHANISMS MEDIATING BEHAVIORAL HYPERALGESIA INDUCED BY NEUROKININ-1 TACHYKININ RECEPTOR ACTIVATION IN THE ROSTRAL VENTROMEDIAL MEDULLA

    PubMed Central

    Lagraize, S. C.; Guo, W.; Yang, K.; Wei, F.; Ren, K.; Dubner, R.

    2010-01-01

    Hyperalgesia in animal injury models is linked to activation of descending raphespinal modulatory circuits originating in the rostral ventromedial medulla (RVM). A neurokinin-1 (NK-1) receptor antagonist microinjected into the RVM before or after inflammation produced by complete Freund’s adjuvant (CFA) resulted in an attenuation of thermal hyperalgesia. A transient (acute) or a continuous infusion of Substance P (SP) microinjected into the RVM of non-inflamed animals led to similar pain hypersensitivity. Intrathecal pretreatment or post-treatment of a 5-HT3 receptor antagonist (Y-25130 or ondansetron) blocked the SP-induced hyperalgesia. The SP-induced hyperalgesia was both GABAA and NMDA receptor-dependent after pre- and post-treatment with selective antagonists at the spinal level. A microinjection of SP into the RVM also led to increased NMDA NR1 receptor subunit phosphorylation in spinal cord tissue. The GABAA receptor-mediated hyperalgesia involved a shift in the anionic gradient in dorsal horn nociceptive neurons and an increase in phosphorylated NKCC1 protein (isoform of the Na-K-Cl cotransporter). Following a low dose of SP infused into the RVM, intrathecal muscimol (GABAA agonist) increased SP-induced thermal hyperalgesia, phosphorylated NKCC1 protein expression, and NMDA NR1 subunit phosphorylation in the spinal cord. The thermal hyperalgesia was blocked by intrathecal gabazine, the GABAA receptor antagonist, and MK-801, the NMDA receptor channel blocker. These findings indicate that NK-1 receptors in the RVM are involved in SP-induced thermal hyperalgesia, this hyperalgesia is 5-HT3-receptor dependent at the spinal level, and involves the functional interaction of spinal GABAA and NMDA receptors. PMID:20888891

  6. Peripheral Receptor Mechanisms Underlying Orofacial Muscle Pain and Hyperalgesia

    NASA Astrophysics Data System (ADS)

    Saloman, Jami L.

    Musculoskeletal pain conditions, particularly those associated with temporomandibular joint and muscle disorders (TMD) are severely debilitating and affect approximately 12% of the population. Identifying peripheral nociceptive mechanisms underlying mechanical hyperalgesia, a prominent feature of persistent muscle pain, could contribute to the development of new treatment strategies for the management of TMD and other muscle pain conditions. This study provides evidence of functional interactions between ligand-gated channels, P2X3 and TRPV1/TRPA1, in trigeminal sensory neurons, and proposes that these interactions underlie the development of mechanical hyperalgesia. In the masseter muscle, direct P2X3 activation, via the selective agonist αβmeATP, induced a dose- and time-dependent hyperalgesia. Importantly, the αβmeATP-induced hyperalgesia was prevented by pretreatment of the muscle with a TRPV1 antagonist, AMG9810, or the TRPA1 antagonist, AP18. P2X3 was co-expressed with both TRPV1 and TRPA1 in masseter muscle afferents confirming the possibility for intracellular interactions. Moreover, in a subpopulation of P2X3 /TRPV1 positive neurons, capsaicin-induced Ca2+ transients were significantly potentiated following P2X3 activation. Inhibition of Ca2+-dependent kinases, PKC and CaMKII, prevented P2X3-mechanical hyperalgesia whereas blockade of Ca2+-independent PKA did not. Finally, activation of P2X3 induced phosphorylation of serine, but not threonine, residues in TRPV1 in trigeminal sensory neurons. Significant phosphorylation was observed at 15 minutes, the time point at which behavioral hyperalgesia was prominent. Similar data were obtained regarding another nonselective cation channel, the NMDA receptor (NMDAR). Our data propose P2X3 and NMDARs interact with TRPV1 in a facilitatory manner, which could contribute to the peripheral sensitization underlying masseter hyperalgesia. This study offers novel mechanisms by which individual pro-nociceptive ligand

  7. Differential regulation of peripheral IL-1β-induced mechanical allodynia and thermal hyperalgesia in rats.

    PubMed

    Kim, Min J; Lee, Sang Y; Yang, Kui Y; Nam, Soon H; Kim, Hyun J; Kim, Young J; Bae, Yong C; Ahn, Dong K

    2014-04-01

    This study examined the differential mechanisms of mechanical allodynia and thermal hyperalgesia after injection of interleukin (IL) 1β into the orofacial area of male Sprague-Dawley rats. The subcutaneous administration of IL-1β produced both mechanical allodynia and thermal hyperalgesia. Although a pretreatment with iodoresiniferatoxin (IRTX), a transient receptor potential vanilloid 1 (TRPV1) antagonist, did not affect IL-1β-induced mechanical allodynia, it significantly abolished IL-1β-induced thermal hyperalgesia. On the other hand, a pretreatment with D-AP5, an N-methyl-d-aspartate (NMDA) receptor antagonist, and NBQX, an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, blocked IL-1β-induced mechanical allodynia. Pretreatment with H89, a protein kinase A (PKA) inhibitor, blocked IL-1β-induced mechanical allodynia but not thermal hyperalgesia. In contrast, pretreatment with chelerythrine, a protein kinase C (PKC) inhibitor, inhibited IL-1β-induced thermal hyperalgesia. Subcutaneous injections of 2% lidocaine, a local anesthetic agent, blocked IL-1β-induced thermal hyperalgesia but not IL-1β-induced mechanical allodynia. In the resiniferatoxin (RTX)-pretreated rats, a subcutaneous injection of IL-1β did not produce thermal hyperalgesia due to the depletion of TRPV1 in the primary afferent fibers. Double immunofluorescence revealed the colocalization of PKA with neurofilament 200 (NF200) and of PKC with the calcitonin gene-related peptide (CGRP) in the trigeminal ganglion. Furthermore, NMDA receptor 1 (NR1) and TRPV1 predominantly colocalize with PKA and PKC, respectively, in the trigeminal ganglion. These results suggest that IL-1β-induced mechanical allodynia is mediated by sensitized peripheral NMDA/AMPA receptors through PKA-mediated signaling in the large-diameter primary afferent nerve fibers, whereas IL-1β-induced thermal hyperalgesia is mediated by sensitized peripheral TRPV1 receptors through PKC-mediated

  8. Acidosis Mediates the Switching of Gs-PKA and Gi-PKCε Dependence in Prolonged Hyperalgesia Induced by Inflammation

    PubMed Central

    Huang, Wei-Yu; Dai, Shih-Ping; Chang, Yan-Ching; Sun, Wei-Hsin

    2015-01-01

    Chronic inflammatory pain, when not effectively treated, is a costly health problem and has a harmful effect on all aspects of health-related quality of life. Previous studies suggested that in male Sprague Dawley rats, prostaglandin E2 (PGE2)-induced short-term hyperalgesia depends on protein kinase A (PKA) activity, whereas long-lasting hyperalgesia induced by PGE2 with carrageenan pre-injection, requires protein kinase Cε (PKCε). However, the mechanism underlying the kinase switch with short- to long-term hyperalgesia remains unclear. In this study, we used the inflammatory agents carrageenan or complete Freund’s adjuvant (CFA) to induce long-term hyperalgesia, and examined PKA and PKCε dependence and switching time. Hyperalgesia induced by both agents depended on PKA/PKCε and Gs/Gi-proteins, and the switching time from PKA to PKCε and from Gs to Gi was about 3 to 4 h after inflammation induction. Among the single inflammatory mediators tested, PGE2 and 5-HT induced transient hyperalgesia, which depended on PKA and PKCε, respectively. Only acidic solution-induced hyperalgesia required Gs-PKA and Gi-PKCε, and the switch time for kinase dependency matched inflammatory hyperalgesia, in approximately 2 to 4 h. Thus, acidosis in inflamed tissues may be a decisive factor to regulate switching of PKA and PKCε dependence via proton-sensing G-protein–coupled receptors. PMID:25933021

  9. Dynamic and static components of mechanical hyperalgesia in human hairy skin.

    PubMed

    Koltzenburg, M; Lundberg, L E; Torebjörk, H E

    1992-11-01

    resulted in a reappearance of on-going pain and hyperalgesia. The effect of a nerve compression block of the superficial radial nerve on these sensations was tested in 14 experiments. When the ability to perceive light touch had been abolished, there was also no touch-evoked pain, indicating that this component of mechanical hyperalgesia is mediated by large-diameter primary afferents. At a later stage of the block when the subjects' ability to perceive cold stimuli had also been lost, application of cool stimuli still eliminated on-going burning pain, suggesting that pain relief afforded by cooling the skin acts at the peripheral receptor level and not by central masking.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:1484717

  10. Acid-sensing ion channel 3 mediates peripheral anti-hyperalgesia effects of acupuncture in mice inflammatory pain

    PubMed Central

    2011-01-01

    Background Peripheral tissue inflammation initiates hyperalgesia accompanied by tissue acidosis, nociceptor activation, and inflammation mediators. Recent studies have suggested a significantly increased expression of acid-sensing ion channel 3 (ASIC3) in both carrageenan- and complete Freund's adjuvant (CFA)-induced inflammation. This study tested the hypothesis that acupuncture is curative for mechanical hyperalgesia induced by peripheral inflammation. Methods Here we used mechanical stimuli to assess behavioral responses in paw and muscle inflammation induced by carrageenan or CFA. We also used immunohistochemistry staining and western blot methodology to evaluate the expression of ASIC3 in dorsal root ganglion (DRG) neurons. Results In comparison with the control, the inflammation group showed significant mechanical hyperalgesia with both intraplantar carrageenan and CFA-induced inflammation. Interestingly, both carrageenan- and CFA-induced hyperalgesia were accompanied by ASIC3 up-regulation in DRG neurons. Furthermore, electroacupuncture (EA) at the ST36 rescued mechanical hyperalgesia through down-regulation of ASIC3 overexpression in both carrageenan- and CFA-induced inflammation. Conclusions In addition, electrical stimulation at the ST36 acupoint can relieve mechanical hyperalgesia by attenuating ASIC3 overexpression. PMID:22070775

  11. Oxidative stress in the spinal cord is an important contributor in capsaicin-induced mechanical secondary hyperalgesia in mice.

    PubMed

    Schwartz, Erica S; Lee, Inhyung; Chung, Kyungsoon; Chung, Jin Mo

    2008-09-15

    Recent studies indicate that reactive oxygen species (ROS) are critically involved in persistent pain primarily through spinal mechanisms, thus suggesting ROS involvement in central sensitization. To investigate ROS involvement in central sensitization, the effects of ROS scavengers and donors on pain behaviors were examined in mice. Capsaicin- induced hyperalgesia was used as a pain model since it has 2 distinctive pain components, primary and secondary hyperalgesia representing peripheral and central sensitization, respectively. Capsaicin (25 microg/5 microl) was injected intradermally into the left hind foot. Foot withdrawal frequencies in response to von Frey filament stimuli were measured and used as an indicator of mechanical hyperalgesia. The production of ROS was examined by using a ROS sensitive dye, MitoSox. Mice developed primary and secondary mechanical hyperalgesia after capsaicin injection. A systemic or intrathecal post-treatment with either phenyl-N-tert-butylnitrone (PBN) or 4-hydroxy-2,2,6,6-tetramethylpiperidine-1 oxyl (TEMPOL), ROS scavengers, significantly reduced secondary hyperalgesia, but not primary hyperalgesia, in a dose-dependent manner. Pretreatment with ROS scavengers also significantly reduced the magnitude and duration of capsaicin-induced secondary hyperalgesia. On the other hand, intrathecal injection of tert-butylhydroperoxide (t-BOOH, 5 microl), a ROS donor, produced a transient hyperalgesia in a dose-dependent manner. The number of MitoSox positive dorsal horn neurons was increased significantly after capsaicin treatment. This study suggests that ROS mediates the development and maintenance of capsaicin-induced hyperalgesia in mice, mainly through central sensitization and that the elevation of spinal ROS is most likely due to increased production of mitochondrial superoxides in the dorsal horn neurons. PMID:18375065

  12. Electroacupuncture suppresses capsaicin-induced secondary hyperalgesia through an endogenous spinal opioid mechanism

    PubMed Central

    Kim, Hee Young; Wang, Jigong; Lee, Inhyung; Kim, Hee Kee; Chung, Kyungsoon; Chung, Jin Mo

    2009-01-01

    Central sensitization, caused either by tissue inflammation or peripheral nerve injury, plays an important role in persistent pain. An animal model of capsaicin-induced pain has well-defined peripheral and central sensitization components, thus is useful for studying the analgesic effect on two separate components. The focus of this study is to examine the analgesic effects of electroacupuncture (EA) on capsaicin-induced secondary hyperalgesia, which represents central sensitization. Capsaicin (0.5%, 10 μl) was injected into the plantar side of the left hind paw, and foot withdrawal thresholds in response to von Frey stimuli (mechanical sensitivity) were determined for both primary and secondary hyperalgesia in rats. EA (2 Hz, 3 mA) was applied to various pairs of acupoints, GB30-GB34, BL40-BL60, GV2-GV6, LI3-LI6 and SI3-TE8, for 30 min under isofluraine anesthesia and then the effect of EA on mechanical sensitivity of paw was determined. EA applied to the ipsilateral SI3-TE8, but none the other acupoints, significantly reduced capsaicin-induced secondary hyperalgesia but not primary hyperalgesia. EA analgesic effect was inhibited by a systemic non-specific opioid receptor (OR) antagonist or an intrathecal μ- or δ-OR antagonist. EA analgesic effect was not affected by an intrathecal κ-OR antagonist or systemic adrenergic receptor antagonist. This study demonstrates that EA produces a stimulation point specific analgesic effect on capsaicin-induced secondary hyperalgesia (central sensitization), mediated by activating endogenous spinal μ and δ opioid receptors. PMID:19646817

  13. Soluble epoxide hydrolase limits mechanical hyperalgesia during inflammation

    PubMed Central

    2011-01-01

    Background Cytochrome-P450 (CYP450) epoxygenases metabolise arachidonic acid (AA) into four different biologically active epoxyeicosatrienoic acid (EET) regioisomers. Three of the EETs (i.e., 8,9-, 11,12- and 14,15-EET) are rapidly hydrolysed by the enzyme soluble epoxide hydrolase (sEH). Here, we investigated the role of sEH in nociceptive processing during peripheral inflammation. Results In dorsal root ganglia (DRG), we found that sEH is expressed in medium and large diameter neurofilament 200-positive neurons. Isolated DRG-neurons from sEH-/- mice showed higher EET and lower DHET levels. Upon AA stimulation, the largest changes in EET levels occurred in culture media, indicating both that cell associated EET concentrations quickly reach saturation and EET-hydrolyzing activity mostly effects extracellular EET signaling. In vivo, DRGs from sEH-deficient mice exhibited elevated 8,9-, 11,12- and 14,15-EET-levels. Interestingly, EET levels did not increase at the site of zymosan-induced inflammation. Cellular imaging experiments revealed direct calcium flux responses to 8,9-EET in a subpopulation of nociceptors. In addition, 8,9-EET sensitized AITC-induced calcium increases in DRG neurons and AITC-induced calcitonin gene related peptide (CGRP) release from sciatic nerve axons, indicating that 8,9-EET sensitizes TRPA1-expressing neurons, which are known to contribute to mechanical hyperalgesia. Supporting this, sEH-/- mice showed increased nociceptive responses to mechanical stimulation during zymosan-induced inflammation and 8,9-EET injection reduced mechanical thresholds in naive mice. Conclusion Our results show that the sEH can regulate mechanical hyperalgesia during inflammation by inactivating 8,9-EET, which sensitizes TRPA1-expressing nociceptors. Therefore we suggest that influencing the CYP450 pathway, which is actually highly considered to treat cardiovascular diseases, may cause pain side effects. PMID:21970373

  14. Epac-protein kinase C alpha signaling in purinergic P2X3R-mediated hyperalgesia after inflammation.

    PubMed

    Gu, Yanping; Li, Guangwen; Chen, Yong; Huang, Li-Yen Mae

    2016-07-01

    Sensitization of purinergic P2X3 receptors (P2X3Rs) is a major mechanism contributing to injury-induced exaggerated pain responses. We showed in a previous study that cyclic adenosine monophosphate (cAMP)-dependent guanine nucleotide exchange factor 1 (Epac1) in rat sensory dorsal root ganglia (DRGs) is upregulated after inflammatory injury, and it plays a critical role in P2X3R sensitization by activating protein kinase C epsilon (PKCε) inside the cells. protein kinase C epsilon has been established as the major PKC isoform mediating injury-induced hyperalgesic responses. On the other hand, the role of PKCα in receptor sensitization was seldom considered. Here, we studied the participation of PKCα in Epac signaling in P2X3R-mediated hyperalgesia. The expression of both Epac1 and Epac2 and the level of cAMP in DRGs are greatly enhanced after complete Freund adjuvant (CFA)-induced inflammation. The expression of phosphorylated PKCα is also upregulated. Complete Freund adjuvant (CFA)-induced P2X3R-mediated hyperalgesia is not only blocked by Epac antagonists but also by the classical PKC isoform inhibitors, Go6976, and PKCα-siRNA. These CFA effects are mimicked by the application of the Epac agonist, 8-(4-chlorophenylthio)-2 -O-methyl-cAMP (CPT), in control rats, further confirming the involvement of Epacs. Because the application of Go6976 prior to CPT still reduces CPT-induced hyperalgesia, PKCα is downstream of Epacs to mediate the enhancement of P2X3R responses in DRGs. The pattern of translocation of PKCα inside DRG neurons in response to CPT or CFA stimulation is distinct from that of PKCε. Thus, in contrast to prevalent view, PKCα also plays an essential role in producing complex inflammation-induced receptor-mediated hyperalgesia. PMID:26963850

  15. Epac–protein kinase C alpha signaling in purinergic P2X3R-mediated hyperalgesia after inflammation

    PubMed Central

    Gu, Yanping; Li, Guangwen; Chen, Yong; Huang, Li-Yen Mae

    2016-01-01

    Abstract Sensitization of purinergic P2X3 receptors (P2X3Rs) is a major mechanism contributing to injury-induced exaggerated pain responses. We showed in a previous study that cyclic adenosine monophosphate (cAMP)–dependent guanine nucleotide exchange factor 1 (Epac1) in rat sensory dorsal root ganglia (DRGs) is upregulated after inflammatory injury, and it plays a critical role in P2X3R sensitization by activating protein kinase C epsilon (PKCε) inside the cells. protein kinase C epsilon has been established as the major PKC isoform mediating injury-induced hyperalgesic responses. On the other hand, the role of PKCα in receptor sensitization was seldom considered. Here, we studied the participation of PKCα in Epac signaling in P2X3R-mediated hyperalgesia. The expression of both Epac1 and Epac2 and the level of cAMP in DRGs are greatly enhanced after complete Freund adjuvant (CFA)–induced inflammation. The expression of phosphorylated PKCα is also upregulated. Complete Freund adjuvant (CFA)–induced P2X3R-mediated hyperalgesia is not only blocked by Epac antagonists but also by the classical PKC isoform inhibitors, Go6976, and PKCα-siRNA. These CFA effects are mimicked by the application of the Epac agonist, 8-(4-chlorophenylthio)-2 -O-methyl-cAMP (CPT), in control rats, further confirming the involvement of Epacs. Because the application of Go6976 prior to CPT still reduces CPT-induced hyperalgesia, PKCα is downstream of Epacs to mediate the enhancement of P2X3R responses in DRGs. The pattern of translocation of PKCα inside DRG neurons in response to CPT or CFA stimulation is distinct from that of PKCε. Thus, in contrast to prevalent view, PKCα also plays an essential role in producing complex inflammation-induced receptor-mediated hyperalgesia. PMID:26963850

  16. Neonatal handling (resilience) attenuates water-avoidance stress induced enhancement of chronic mechanical hyperalgesia in the rat

    PubMed Central

    Alvarez, Pedro; Levine, Jon D.; Green, Paul G.

    2015-01-01

    Chronic stress is well known to exacerbate pain. We tested the hypothesis that neonatal handling, which induces resilience to the negative impact of stress by increasing the quality and quantity of maternal care, attenuates the mechanical hyperalgesia produced by water-avoidance stress in the adult rat. Neonatal male rats underwent the handling protocol on postnatal days 2–9, weaned at 21 days and tested for muscle mechanical nociceptive threshold at postnatal days 50–75. Decrease in mechanical nociceptive threshold in skeletal muscle in adult rats, produced by exposure to water-avoidance stress, was significantly attenuated by neonatal handling. Neonatal handling also attenuated the mechanical hyperalgesia produced by intramuscular administration of the pronociceptive inflammatory mediator, prostaglandin E2 in rats exposed as adults to water-avoidance stress. Neonatal handling, which induces a smaller corticosterone response in adult rats exposed to a stressor as well as changes in central nervous system neurotransmitter systems, attenuates mechanical hyperalgesia produced by water-avoidance stress and enhanced prostaglandin hyperalgesia in adult animals. PMID:25637700

  17. Activation of NMDA receptors in the brainstem, RVM and NGC, mediates mechanical hyperalgesia produced by repeated intramuscular injections of acidic saline in rats

    PubMed Central

    Da Silva, LFS; DeSantana, JM; Sluka, KA

    2010-01-01

    Repeated injections of acidic saline into the gastrocnemius muscle induced both muscle and cutaneous hypersensitivity. We have previously shown that microinjection of local anesthetic into either the rostral ventromedial medulla (RVM) or the nucleus reticularis gigantocellularis (NGC) reverses this muscle and cutaneous hypersensitivity. Although prior studies show that NMDA receptors in the RVM play a clear role in mediating visceral and inflammatory hypersensitivity, the role of NMDA receptors in the NGC, or in non-inflammatory muscle pain is unclear. Therefore, the present study evaluated involvement of the NMDA receptors in the RVM and NGC in muscle and cutaneous hypersensitivity induced by repeated intramuscular injections of acidic saline. Repeated intramuscular injections of acidic saline, 5 days apart, resulted in a bilateral decrease in the withdrawal thresholds of the paw and muscle in all groups 24 h after the second injection. Microinjection of NMDA receptor antagonists into the RVM reversed both the muscle and cutaneous hypersensitivity. However, microinjection of NMDA receptor antagonists into the NGC only reversed cutaneous, but not muscle hypersensitivity. These results suggest that NMDA receptors in the RVM mediate both muscle and cutaneous hypersensitivity, but those in the NGC mediated only cutaneous hypersensitivity after muscle insult. PMID:19853525

  18. The role of reactive oxygen species in capsaicin-induced mechanical hyperalgesia and in the activities of dorsal horn neurons.

    PubMed

    Lee, Inhyung; Kim, Hee Kee; Kim, Jae Hyo; Chung, Kyungsoon; Chung, Jin Mo

    2007-12-15

    Previous findings that reactive oxygen species (ROS) are involved in neuropathic pain, mainly through spinal mechanisms, suggest that ROS may be involved in central sensitization. To investigate the possible role of ROS in central sensitization, we examined in rats the effects of ROS scavengers on capsaicin-induced secondary hyperalgesia, which is known to be mediated by central sensitization. We used two different ROS scavengers: phenyl N-tert-butylnitrone (PBN) and 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL). Intradermal capsaicin injection (20 microg in 20 microl olive oil) into the hind paw produced primary and secondary hyperalgesia. A systemic administration of PBN (100mg/kg, i.p.) or TEMPOL (200mg/kg, i.p.) alleviated capsaicin-induced secondary, but not primary, hyperalgesia. Intrathecal injection of PBN (1mg inof veterinary Surgery/anesthesiology, College of veterinary Medic 50 microl saline) greatly reduced hyperalgesia, whereas intracerebroventricular or intradermal injection of PBN produced only a minor analgesic effect, suggesting that PBN takes effect mainly through the spinal cord. Electrophysiological recordings from wide dynamic range (WDR) neurons in the dorsal horn showed that intradermal capsaicin enhanced the evoked responses to peripheral stimuli; systemic PBN or TEMPOL restored the responses to normal levels. Removal of ROS thus restored the responsiveness of spinal WDR neurons to normal levels, suggesting that ROS is involved in central sensitization, at least in part by sensitizing WDR neurons. PMID:17379413

  19. siRNA-mediated downregulation of GluN2B in the rostral anterior cingulate cortex attenuates mechanical allodynia and thermal hyperalgesia in a rat model of pain associated with bone cancer

    PubMed Central

    XU, YONGGUANG; WANG, GONGMING; ZOU, XULI; YANG, ZAIQI; WANG, QIN; FENG, HAO; ZHANG, MENGYUAN

    2016-01-01

    It has previously been suggested that the upregulation of GluN2B-containing N-methyl D-aspartate receptors (GluN2B) within the rostral anterior cingulate cortex (rACC) may contribute to the development of chronic pain. The present study used a rat model of bone cancer pain in order to investigate whether lentiviral-mediated delivery of small interfering RNAs targeting GluN2B (LV-GluN2B) could attenuate pain associated with bone cancer, by selectively decreasing GluN2B expression within the rACC. Sprague Dawley rats were inoculated with osteosarcoma cells into the intramedullary space of the right tibia in order to induce persistent bone cancer-associated pain. Intra-rACC administration of the lentiviral siRNA was performed in the tumor bearing rats; and reverse transcription-quantitative polymerase chain reaction and western blotting were performed in order to detect the expression levels of GluN2B. Pain behavior changes were evaluated via paw withdrawal threshold and latency determinations. Marked and region-selective decreases in the mRNA and protein expression levels of GluN2B were detected in the rACC following the intra-rACC administration of LV-GluN2B. Furthermore, the rats also exhibited pain behavior changes corresponding to the decreased levels of GluN2B. By post-operative day 14, inoculation of osteosarcoma cells had significantly enhanced mechanical allodynia and thermal hyperalgesia in the rats, which were subsequently attenuated by the intra-rACC administration of LV-GluN2B. Notably, the paw withdrawal threshold and latency of the tumor-bearing rats had recovered to normal levels, by day 14 post-administration. The results of the present study suggest that GluN2B within the rACC may be a potential target for RNA interference therapy for the treatment of pain associated with bone cancer. Furthermore, the lentiviral vector delivery strategy may be a promising novel approach for the treatment of bone cancer pain. PMID:26889244

  20. Mast cell degranulation mediates compound 48/80-induced hyperalgesia in mice

    PubMed Central

    Chatterjea, Devavani; Wetzel, Abigail; Mack, Madison; Engblom, Camilla; Allen, Juliann; Mora-Solano, Carolina; Paredes, Luisa; Balsells, Evelyn; Martinov, Tijana

    2012-01-01

    Mast cells mediate allergies, hypersensitivities, host defense, and venom neutralization. An area of recent interest is the contribution of mast cells to inflammatory pain. Here we found that specific, local activation of mast cells produced plantar hyperalgesia in mice. Basic secretagogue compound 48/80 induced plantar mast cell degranulation accompanied by thermal hyperalgesia, tissue edema, and neutrophil influx in the hindpaws of ND4 Swiss mice. Blocking mast cell degranulation, neutrophil extravasation, and histamine signaling abrogated these responses. Compound 48/80 also produced edema, pain, and neutrophil influx in WT C57BL/6 but not in genetically mast cell-deficient C57BL/6-KitW-sh/W-sh mice. These responses were restored following plantar reconstitution with bone marrow-derived cultured mast cells. PMID:22828511

  1. The spinal antinociceptive mechanism determined by systemic administration of BD1047 in zymosan-induced hyperalgesia in rats.

    PubMed

    Jeong, Young Chan; Son, Ji Seon; Kwon, Young Bae

    2015-10-01

    Although sigma-1 receptor (Sig-1R) antagonists have a potential antinociceptive effect in inflammatory diseases, the precise mechanism is not fully understood. The present study was aimed to elucidate the role of spinal neurons and microglia in the anti-nociceptive mechanism of BD1047 (a prototypical Sig-1R antagonist) using an inflammatory pain model based on intraplantar injection of zymosan. Oral pretreatment with BD1047 dose-dependently reduced zymosan-induced thermal and mechanical hyperalgesia as well as spinal neuronal activation including increased immunoreactivity of Fos, protein kinase C (PKC) and 'PKC-dependent phosphorylation of the NMDA receptor subunit 1' (pNR1). Zymosan also led to increased CD11b immunoreactivity (a marker of microglia) accompanied by 'phosphorylated p38 mitogen activated protein kinase' (p-p38MAPK) and interleukin-1βimmunoreactivity in the spinal dorsal horn. Intrathecal injection of a microglia modulator (minocycline), p38MAPK inhibitor (SB203580) or interleukin-1βneutralizing antibody significantly attenuated zymosan-induced hyperalgesia. Specifically, oral pretreatment with BD1047 reduced the immunoreactivity of CD11b, p-p38MAPK and interleukin-1β. In the spinal cord section, Sig-1R immunoreactivity was exclusively distributed in both spinal dorsal horn neurons and central endings of unmyelinated primary afferent fibers but not in glia. Intrathecal injection of BD1047 alleviated zymosan-induced hyperalgesia up to the level of oral administration. Taken together, our data imply that antinociceptive effect induced by oral treatment with BD1047 may be mediated, at least in part, by the inhibition of neuronal and microglial activation in the spinal cord triggered by inflammatory conditions. PMID:26434709

  2. Dynamic mechanical assessment of muscle hyperalgesia in humans: The dynamic algometer

    PubMed Central

    Finocchietti, Sara; Graven-Nielsen, Thomas; Arendt-Nielsen, Lars

    2015-01-01

    BACKGROUND: Musculoskeletal pain is often associated with a nonhomogeneous distribution of mechanical hyperalgesia. Consequently, new methods able to detect this distribution are needed. OBJECTIVE: To develop and test a new method for assessing muscle hyperalgesia with high temporal and spatial resolution that provides complementary information compared with information obtained by traditional static pressure algometry. METHODS: The dynamic pressure algometer was tested bilaterally on the tibialis anterior muscle in 15 healthy subjects and compared with static pressure algometry. The device consisted of a wheel that was rolled over the muscle tissue with a fixed velocity and different predefined forces. The pain threshold force was determined and pain intensity to a fixed-force stimulation was continuously rated on a visual analogue scale while the wheel was rolling over the muscle. The pressure pain sensitivity was evaluated before, during, and after muscle pain and hyperalgesia induced unilaterally by either injection of hypertonic saline (0.5 mL, 6%) into the tibialis anterior or eccentric exercise evoking delayed-onset muscle soreness (DOMS). RESULTS: The intraclass correlation coefficient was >0.88 for the dynamic thresholds; thus, the method was reliable. Compared with baseline, both techniques detected hyperalgesia at the saline injection site and during DOMS (P<0.05). The dynamic algometer also detected the widespread, patchy distribution of sensitive loci during DOMS, which was difficult to evaluate using static pressure algometry. DISCUSSION AND CONCLUSION: The present study showed that dynamic pressure algometry is a reliable tool for evaluating muscle hyperalgesia (threshold and pain rating) with high temporal and spatial resolution. It can be applied as a simple clinical bed-side test and as a quantitative tool in pharmacological profiling studies. PMID:25664539

  3. L-Tetrahydropalmatine alleviates mechanical hyperalgesia in models of chronic inflammatory and neuropathic pain in mice.

    PubMed

    Zhou, Hai-Hui; Wu, Dan-Lian; Gao, Li-Yan; Fang, Yun; Ge, Wei-Hong

    2016-05-01

    Chronic pain is categorized as inflammatory and neuropathic, and there are common mechanisms underlying the generation of each pain state. Such pain is difficult to treat and the treatment at present is inadequate. Corydalis yanhusuo is a traditional Chinese medicine with demonstrated analgesic efficacy in humans. The potential antihyperalgesic effect of its active component is L-tetrahydropalmatine (L-THP). L-THP has been used for the treatment of headache and other mild pain. However, little is known about its analgesic effect on chronic pain and its mechanism. Here, we report that L-THP exerts remarkable antihyperalgesic effects on neuropathic and inflammatory pain in animal models. Neuropathic hypersensitivity was induced by segmental spinal nerve ligation and inflammatory hypersensitivity was induced by an intraplantar injection of complete Freund's adjuvant. To determine the receptor mechanism underlying the antihyperalgesic actions of L-THP, we used SCH23390, an antagonist of a dopamine D1 receptor, in an attempt to block the antihyperalgesic effects of L-THP. We found that L-THP (1-4 mg/kg, i.p.) produced a dose-dependent antihyperalgesic effect in spinal nerve ligation and complete Freund's adjuvant models. The antihyperalgesic effects of L-THP were abolished by a dopamine D1 receptor antagonist SCH23390 (0.02 mg/kg). Furthermore, L-THP (4 mg/kg, i.p.) did not influence motor function. These findings suggest that L-THP may ameliorate mechanical hyperalgesia by enhancing dopamine D1 receptor-mediated dopaminergic transmission. PMID:26981712

  4. Morphine hyperalgesia gated through microglia-mediated disruption of neuronal Cl− homeostasis

    PubMed Central

    Ferrini, Francesco; Trang, Tuan; Mattioli, Theresa-Alexandra M.; Laffray, Sophie; Del’Guidice, Thomas; Lorenzo, Louis-Etienne; Castonguay, Annie; Doyon, Nicolas; Zhang, Wenbo; Godin, Antoine G.; Mohr, Daniela; Beggs, Simon; Vandal, Karen; Beaulieu, Jean-Martin; Cahill, Catherine; Salter, Michael W.; De Koninck, Yves

    2016-01-01

    A major unresolved issue in treating pain is the paradoxical hyperalgesia produced by the gold-standard analgesic morphine and other opiates. We show here that hyperalgesia-inducing treatment with morphine causes downregulation of the K+-Cl− cotransporter KCC2, impairing Cl− homeostasis in spinal lamina l neurons. Restoring Eanion reversed the morphine-induced hyperalgesia without affecting tolerance. The hyperalgesia was also reversed by ablating spinal microglia. Morphine hyperalgesia, but not tolerance, required μ opioid receptor-dependent expression of P2X4 receptors (P2X4Rs) in microglia and μ-independent gating of the release of brain-derived neurotrophic factor (BDNF) by P2X4Rs. Blocking BDNF-TrkB signalling preserved Cl− homeostasis and reversed the hyperalgesia. Gene-targeted mice in which BDNF was deleted from microglia did not develop hyperalgesia to morphine. Yet, neither morphine antinociception nor tolerance was affected in these animals. Our findings dissociate morphine-induced hyperalgesia from tolerance and unveil the microglia-to-neuron P2X4-BDNF-KCC2 pathway as a therapeutic target to prevent hyperalgesia without affecting morphine analgesia. PMID:23292683

  5. Anti-Nociceptive Effect of Resveratrol During Inflammatory Hyperalgesia via Differential Regulation of pro-Inflammatory Mediators.

    PubMed

    Singh, Ajeet Kumar; Vinayak, Manjula

    2016-07-01

    Sensitization of nociceptive neurons by inflammatory mediators leads to hypersensitivity for normal painful stimuli which is termed hyperalgesia. Oxidative stress is an essential factor in pathological pain; therefore, antioxidants qualify as potential anti-hyperalgesic agents. The present study examines the efficacy of the natural antioxidant resveratrol in complete Freund's adjuvant (CFA) induced hyperalgesic rats. Thermal hyperalgesia was measured at different time points by paw withdrawal latency test and confirmed by c-Fos expression in spinal dorsal horn. The impact of resveratrol treatment on inflammatory mediators at peripheral (paw skin) and central (spinal cord) sites was determined during early (6 h) as well as late phase (48 h) of hyperalgesia. Intraplanter injection of CFA increased the level of cytokines IL-1β, TNF-α and IL-6 as well as inflammatory enzymes COX-2 and iNOS in paw skin in both phases. In case of spinal cord, the level of COX-2 was found to be elevated in both phases, whereas iNOS could not be detected. The cytokines were found to be elevated only in late phase in spinal cord. Administration of resveratrol (20 mg/kg) shifted the level of all inflammatory mediators towards normal, except cytokines in paw skin. The present study suggests that the anti-nociceptive effect of resveratrol is implicated at both peripheral and central sites in a tissue specific manner. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27060370

  6. Swim therapy reduces mechanical allodynia and thermal hyperalgesia induced by chronic constriction nerve injury in rats

    PubMed Central

    Shen, Jun; Fox, Lyle E.; Cheng, Jianguo

    2013-01-01

    Objective Neuropathic pain is common and often difficult to treat because it generally does not respond well to the currently available pain medications or nerve blocks. Recent studies in both humans and animals have suggested that exercise may induce a transient analgesia and reduce acute pain in normal healthy individuals. We examined whether swim therapy could alleviate neuropathic pain in rats. Design Rats were trained to swim over a two week period in warm water. After the rats were trained, neuropathic pain was induced by constricting the right sciatic nerve and regular swimming was resumed. The sensitivity of each hind paw was monitored using the Hargreaves test and von Frey test to evaluate the withdrawal response thresholds to heat and touch. Results The paw ipsilateral to the nerve ligation expressed pain-like behaviors including thermal hyperalgesia and mechanical allodynia. Regular swim therapy sessions significantly reduced the mechanical allodynia and thermal hyperalgesia. Swim therapy had little effect on the withdrawal thresholds for the contralateral paw. In addition, swim therapy alone did not alter the thermal or mechanical thresholds of normal rats. Conclusions The results suggest that regular exercise, including swim therapy, may be an effective treatment for neuropathic pain caused by nerve injuries. This study, showing that swim therapy reduces neuropathic pain behavior in rats, provides a scientific rationale for clinicians to test the efficacy of exercise in the management of neuropathic pain. It may prove to be a safe and cost-effective therapy in a variety of neuropathic pain states. PMID:23438327

  7. Combined action of vasoactive amines and bradykinin mediates allergen-evoked thermal hyperalgesia in rats.

    PubMed

    Lavich, Tatiana R; Cordeiro, Renato S B; Calixto, João B; e Silva, Patrícia M R; Martins, Marco A

    2003-02-21

    The ability of allergens to induce hyperalgesia in immunoglobulin E (IgE)-sensitized rats was investigated. The left hind paws of Wistar rats were sensitized with intraplantar injections of IgE anti-dinitrophenylated bovine serum albumin monoclonal antibody, and challenged with dinitrophenylated bovine serum albumin 24 h later. Allergen challenge yielded rapid thermal hyperalgesia and oedema formation in the ipsilateral paws, both reaching a plateau from 15 min to 3 h, and both diminishing thereafter. Allergen-evoked hyperalgesia was inhibited by intraperitoneal treatment with meclizine or methysergide, histamine and 5-hydroxytryptamine receptor antagonists. There was also sensitivity to local treatment with either bradykinin B(1) or B(2) receptor antagonists, des-Arg(9)-[Leu(8)]-bradykinin or D-arginyl-[Hyp3, Thi5, D-Tic7, Oic8]-bradykinin (Hoe 140). Anaphylactic hyperalgesia was mimicked by the combined administration of histamine, 5-hydroxytryptamine and bradykinin at doses which were ineffective when injected alone. This synergistic effect was abolished by treatment with either meclizine, methysergide, Hoe 140 or des-Arg(9)-[Leu(8)]-bradykinin. Our findings show that local thermal hyperalgesia is a feature of allergen-evoked inflammation, and that a synergistic interaction among bradykinin, 5-hydroxytryptamine and histamine plays a critical role in this phenomenon. PMID:12591112

  8. Bilateral mechanical and thermal hyperalgesia and tactile allodynia after chronic compression of dorsal root ganglion in mice.

    PubMed

    Chen, Rong-Gui; Kong, Wei-Wei; Ge, Da-Long; Luo, Ceng; Hu, San-Jue

    2011-08-01

    OBJECTIVE Low back pain is one of the most inextricable problems encountered in clinics. Animal models that imitate symptoms in humans are valuable tools for investigating low back pain mechanisms and the possible therapeutic applications. With the development of genetic technology in pain field, the possibility of mutating specific genes in mice has provided a potent tool for investigating the specific mechanisms of pain. The aim of the present study was to develop a mouse model of chronic compression of dorsal root ganglion (CCD), in which gene mutation can be applied to facilitate the studies of chronic pain. METHODS Chronic compression of L4 and L5 dorsal root ganglia was conducted in mice by inserting fine stainless steel rods into the intervertebral foramina, one at L4 and the other at L5. Mechanical allodynia and thermal hyperalgesia were examined with von Frey filaments and radiating heat stimulator, respectively. RESULTS The CCD mice displayed dramatic mechanical and thermal hyperalgesia as well as tactile allodynia in the hindpaw ipsilateral to CCD. In addition, this mechanical and thermal hyperalgesia as well as tactile allodynia was also found to spread to the contralateral hindpaw. CONCLUSION This model, combined with the possible genetic modification, will strengthen our knowledge of the underlying mechanisms of low back pain. It also favors the development of new treatment strategies for pain and hyperalgesia after spinal injury and other disorders which affect the dorsal root ganglion in humans. PMID:21788994

  9. Mechanical and thermal hyperalgesia and ectopic neuronal discharge after chronic compression of dorsal root ganglia.

    PubMed

    Song, X J; Hu, S J; Greenquist, K W; Zhang, J M; LaMotte, R H

    1999-12-01

    Chronic compression of the dorsal root ganglion (CCD) was produced in adult rats by implanting a stainless steel rod unilaterally into the intervertebral foramen, one rod at L(4) and another at L(5). Two additional groups of rats received either a sham surgery or an acute injury consisting of a transient compression of the ganglion. Withdrawal of the hindpaw was used as evidence of a nocifensive response to mechanical and thermal stimulation of the plantar surface. In addition, extracellular electrophysiological recordings of spontaneous discharges were obtained from dorsal root fibers of formerly compressed ganglia using an in vitro nerve-DRG-dorsal root preparation. The mean threshold force of punctate indentation and the mean threshold temperature of heating required to elicit a 50% incidence of foot withdrawal ipsilateral to the CCD were significantly lower than preoperative values throughout the 35 days of postoperative testing. The number of foot withdrawals ipsilateral to the CCD during a 20-min contact with a temperature-controlled floor was significantly increased over preoperative values throughout postoperative testing when the floor was 4 degrees C (hyperalgesia) and, to a lesser extent, when it was 30 degrees C (spontaneous pain). Stroking the foot with a cotton wisp never elicited a reflex withdrawal before surgery but did so in most rats tested ipsilateral to the CCD during the first 2 postoperative weeks. In contrast, the CCD produced no changes in responses to mechanical or thermal stimuli on the contralateral foot. The sham operation and acute injury produced no change in behavior other than slight, mechanical hyperalgesia for approximately 1 day, ipsilateral to the acute injury. Ectopic spontaneous discharges generated within the chronically compressed ganglion and, occurring in the absence of blood-borne chemicals and without an intact sympathetic nervous system, were recorded from neurons with intact, conducting, myelinated or unmyelinated

  10. Reactive Oxygen Species Donors Increase the Responsiveness of Dorsal Horn Neurons and Induce Mechanical Hyperalgesia in Rats

    PubMed Central

    Kim, Hee Young; Lee, Inhyung; Chun, Sang Woo; Kim, Hee Kee

    2015-01-01

    Our previous studies suggest that reactive oxygen species (ROS) scavengers have analgesic effect on neuropathic pain through spinal mechanisms in the rat. The studies suggest that superoxide in spinal cord is one of important mediators of persistent pain. To test the hypothesis that increase of superoxide-derived intermediates leads to central sensitization and pain, the effects of an intrathecal injection of chemical ROS donors releasing either OH∙, OCl−, or H2O2 were examined on pain behaviors. Following treatment with t-BOOH (OH∙ donor), dorsal horn neuron responses to mechanical stimuli in normal rats and the changes of neuronal excitability were explored on substantia gelatinosa (SG) neurons using whole-cell patch clamping recordings. Intrathecal administration of t-BOOH or NaOCl (OCl− donor), but not H2O2, significantly decreased mechanical thresholds of hind paws. The responses of wide dynamic range neurons to mechanical stimuli increased after a local application of t-BOOH. The t-BOOH increased the frequency and the amplitude of excitatory postsynaptic potentials, depolarized membrane potential in SG neurons, and increased the frequency of action potentials evoked by depolarizing current pulses. These results suggest that elevated ROS, especially OH∙, in the spinal cord sensitized dorsal horn neurons and produced hyperalgesia in normal rats. PMID:26457204

  11. Tetrodotoxin suppresses thermal hyperalgesia and mechanical allodynia in a rat full thickness thermal injury pain model.

    PubMed

    Salas, Margaux M; McIntyre, Matthew K; Petz, Lawrence N; Korz, Walter; Wong, Donald; Clifford, John L

    2015-10-21

    Burn injuries have been identified as the primary cause of injury in 5% of U.S. military personnel evacuated from Operations Iraqi Freedom and Enduring Freedom. Severe burn-associated pain is typically treated with opioids such as fentanyl, morphine, and methadone. Side effects of opioids include respiratory depression, cardiac depression, decrease in motor and cognitive function, as well as the development of hyperalgesia, tolerance and dependence. These effects have led us to search for novel analgesics for the treatment of burn-associated pain in wounded combat service members. Tetrodotoxin (TTX) is a selective voltage-gated sodium channel blocker currently in clinical trials as an analgesic. A phase 3 clinical trial for cancer-related pain has been completed and phase 3 clinical trials on chemotherapy-induced neuropathic pain are planned. It has also been shown in mice to inhibit the development of chemotherapy-induced neuropathic pain. TTX was originally identified as a neurotoxin in marine animals but has now been shown to be safe in humans at therapeutic doses. The antinociceptive effects of TTX are thought to be due to inhibition of Na(+) ion influx required for initiation and conduction of nociceptive impulses. One TTX sensitive sodium channel, Nav1.7, has been shown to be essential in lowering the heat pain threshold after burn injuries. To date, the analgesic effect of TTX has not been tested in burn-associated pain. Male Sprague-Dawley rats were subjected to a full thickness thermal injury on the right hind paw. TTX (8 μg/kg) was administered once a day systemically by subcutaneous injection beginning 3 days post thermal injury and continued through 7 days post thermal injury. Thermal hyperalgesia and mechanical allodynia were assessed 60 and 120 min post injection on each day of TTX treatment. TTX significantly reduced thermal hyperalgesia at all days tested and had a less robust, but statistically significant suppressive effect on mechanical

  12. The Major Brain Endocannabinoid 2-AG Controls Neuropathic Pain and Mechanical Hyperalgesia in Patients with Neuromyelitis Optica

    PubMed Central

    Pellkofer, Hannah L.; Havla, Joachim; Hauer, Daniela; Schelling, Gustav; Azad, Shahnaz C.; Kuempfel, Tania

    2013-01-01

    Recurrent myelitis is one of the predominant characteristics in patients with neuromyelitis optica (NMO). While paresis, visual loss, sensory deficits, and bladder dysfunction are well known symptoms in NMO patients, pain has been recognized only recently as another key symptom of the disease. Although spinal cord inflammation is a defining aspect of neuromyelitis, there is an almost complete lack of data on altered somatosensory function, including pain. Therefore, eleven consecutive patients with NMO were investigated regarding the presence and clinical characteristics of pain. All patients were examined clinically as well as by Quantitative Sensory Testing (QST) following the protocol of the German Research Network on Neuropathic Pain (DFNS). Additionally, plasma endocannabinoid levels and signs of chronic stress and depression were determined. Almost all patients (10/11) suffered from NMO-associated neuropathic pain for the last three months, and 8 out of 11 patients indicated relevant pain at the time of examination. Symptoms of neuropathic pain were reported in the vast majority of patients with NMO. Psychological testing revealed signs of marked depression. Compared to age and gender-matched healthy controls, QST revealed pronounced mechanical and thermal sensory loss, strongly correlated to ongoing pain suggesting the presence of deafferentation-induced neuropathic pain. Thermal hyperalgesia correlated to MRI-verified signs of spinal cord lesion. Heat hyperalgesia was highly correlated to the time since last relapse of NMO. Patients with NMO exhibited significant mechanical and thermal dysesthesia, namely dynamic mechanical allodynia and paradoxical heat sensation. Moreover, they presented frequently with either abnormal mechanical hypoalgesia or hyperalgesia, which depended significantly on plasma levels of the endogenous cannabinoid 2-arachidonoylglycerole (2-AG). These data emphasize the high prevalence of neuropathic pain and hyperalgesia in patients

  13. Auraptenol attenuates vincristine-induced mechanical hyperalgesia through serotonin 5-HT1A receptors.

    PubMed

    Wang, Yunfei; Cao, Shu-e; Tian, Jianmin; Liu, Guozhe; Zhang, Xiaoran; Li, Pingfa

    2013-01-01

    Common chemotherapeutic agents such as vincristine often cause neuropathic pain during cancer treatment in patients. Such neuropathic pain is refractory to common analgesics and represents a challenging clinical issue. Angelicae dahuricae radix is an old traditional Chinese medicine with demonstrated analgesic efficacy in humans. However, the active component(s) that attribute to the analgesic action have not been identified. This work described the anti-hyperalgesic effect of one coumarin component, auraptenol, in a mouse model of chemotherapeutic agent vincristine-induced neuropathic pain. We reported that auraptenol dose-dependently reverted the mechanical hyperalgesia in mice within the dose range of 0.05-0.8 mg/kg. In addition, the anti-hyperalgesic effect of auraptenol was significantly blocked by a selective serotonin 5-HT1A receptor antagonist WAY100635 (1 mg/kg). Within the dose range studied, auraptenol did not significantly alter the general locomotor activity in mice. Taken together, this study for the first time identified an active component from the herbal medicine angelicae dahuricae radix that possesses robust analgesic efficacy in mice. These data support further studies to assess the potential of auraptenol as a novel analgesic for the management of neuropathic pain. PMID:24287473

  14. Assessment of morphine-induced hyperalgesia and analgesic tolerance in mice using thermal and mechanical nociceptive modalities.

    PubMed

    Elhabazi, Khadija; Ayachi, Safia; Ilien, Brigitte; Simonin, Frédéric

    2014-01-01

    Opioid-induced hyperalgesia and tolerance severely impact the clinical efficacy of opiates as pain relievers in animals and humans. The molecular mechanisms underlying both phenomena are not well understood and their elucidation should benefit from the study of animal models and from the design of appropriate experimental protocols. We describe here a methodological approach for inducing, recording and quantifying morphine-induced hyperalgesia as well as for evidencing analgesic tolerance, using the tail-immersion and tail pressure tests in wild-type mice. As shown in the video, the protocol is divided into five sequential steps. Handling and habituation phases allow a safe determination of the basal nociceptive response of the animals. Chronic morphine administration induces significant hyperalgesia as shown by an increase in both thermal and mechanical sensitivity, whereas the comparison of analgesia time-courses after acute or repeated morphine treatment clearly indicates the development of tolerance manifested by a decline in analgesic response amplitude. This protocol may be similarly adapted to genetically modified mice in order to evaluate the role of individual genes in the modulation of nociception and morphine analgesia. It also provides a model system to investigate the effectiveness of potential therapeutic agents to improve opiate analgesic efficacy. PMID:25145878

  15. Assessment of Morphine-induced Hyperalgesia and Analgesic Tolerance in Mice Using Thermal and Mechanical Nociceptive Modalities

    PubMed Central

    Elhabazi, Khadija; Ayachi, Safia; Ilien, Brigitte; Simonin, Frédéric

    2014-01-01

    Opioid-induced hyperalgesia and tolerance severely impact the clinical efficacy of opiates as pain relievers in animals and humans. The molecular mechanisms underlying both phenomena are not well understood and their elucidation should benefit from the study of animal models and from the design of appropriate experimental protocols. We describe here a methodological approach for inducing, recording and quantifying morphine-induced hyperalgesia as well as for evidencing analgesic tolerance, using the tail-immersion and tail pressure tests in wild-type mice. As shown in the video, the protocol is divided into five sequential steps. Handling and habituation phases allow a safe determination of the basal nociceptive response of the animals. Chronic morphine administration induces significant hyperalgesia as shown by an increase in both thermal and mechanical sensitivity, whereas the comparison of analgesia time-courses after acute or repeated morphine treatment clearly indicates the development of tolerance manifested by a decline in analgesic response amplitude. This protocol may be similarly adapted to genetically modified mice in order to evaluate the role of individual genes in the modulation of nociception and morphine analgesia. It also provides a model system to investigate the effectiveness of potential therapeutic agents to improve opiate analgesic efficacy. PMID:25145878

  16. The involvement of the transient receptor potential A1 (TRPA1) in the maintenance of mechanical and cold hyperalgesia in persistent inflammation.

    PubMed

    da Costa, Diogo Santos M; Meotti, Flavia Carla; Andrade, Edinéia Lemos; Leal, Paulo César; Motta, Emerson Marcelo; Calixto, João B

    2010-03-01

    This study investigated the role of TRPA1 in the development and maintenance of mechanical and cold hyperalgesia in persistent inflammation induced by Complete Freund's Adjuvant (CFA) in mice. The intraplantar (i.pl.) injection of CFA induced a long lasting (28 days) hyperalgesia for both mechanical and thermal (cold) stimuli. The intraperitoneal (i.p., 30-300 mg/kg), intraplantar (i.pl., 100 microg/site) or intrathecal (i.t., 10 microg/site) injection of the TRPA1 selective antagonist HC-030031 significantly reduced the mechanical hyperalgesia evaluated by the von Frey hair test. The effect of HC-030031 was evidenced on the day after CFA injection and was kept throughout the test. However, the intracerebroventricular (i.c.v., 10 microg/site) injection of HC-030031 did not interfere with CFA-induced hyperalgesia. Treatment with HC-030031 (300 mg/kg, i.p.) completely inhibited the noxious cold hyperalgesia induced by tetrafluoroethane in mice that received CFA. The pre-treatment with the TRPA1 oligonucleotide antisense (AS-ODN, i.t.) consistently prevented both mechanical and cold hyperalgesia. Interestingly, both TRPA1 protein expression and mRNA were over-expressed in spinal cord and dorsal root ganglia (DRG) of mice treated with CFA, an effect that was fully prevented by the pre-treatment with the TRPA1 antagonist HC-030031. Collectively, the present results showed that TRPA1 present at either peripheral or spinal sites play a relevant role in the development and maintenance of both mechanical and cold hyperalgesia during CFA-induced inflammation. Thus, TRPA1 selective antagonists represent promising candidates to treat hyperalgesia in persistent inflammatory states. PMID:20056530

  17. Spinal cord stimulation reduces mechanical hyperalgesia and glial cell activation in animals with neuropathic pain

    PubMed Central

    Sato, Karina L.; Johanek, Lisa M.; Sanada, Luciana S.; Sluka, Kathleen A.

    2015-01-01

    Spinal cord stimulation (SCS) is used to manage chronic intractable neuropathic pain. We examined parameters of SCS in rats with spared nerve injury by modulating frequency (4Hz vs. 60Hz), duration (30m vs. 6h), or intensity (50%, 75%, or 90% MT). To elucidate potential mechanisms modulated by SCS, we examined immunoreactivity glial markers in the spinal cord after SCS). An epidural SCS lead was implanted in the upper lumbar spinal cord. Animals were tested for mechanical withdrawal threshold (MWT) of the paw before and 2 weeks after SNI, before and after SCS daily for 4 days, and for 9 days after SCS. Seperate groups of animals were tested for glial immunoreactivity after 4 days of 6h SCS. All rats showed a decrease in MWT 2 weeks after nerve injury and an increase in glial activation. For frequency, 4Hz or 60Hz SCS reversed the MWT when compared to sham SCS. For duration, 6h of SCS showed a greater reduction in MWT when compared to 30 min. For intensity, 90% MT was greater than 75% MT and both were greater than 50% MT or sham SCS. SCS decreased glial activation (GFAP, MCP-1 and OX-42) in the spinal cord dorsal horn when compared to sham. In conclusion, 4Hz and 60Hz SCS for a 6h at 90% MT were the most effective parameters for reducing hyperalgesia, suggesting parameters of stimulation are important for effectiveness of SCS. SCS reduced glial activation at the level of the spinal cord suggesting reduction in central excitability. PMID:24361846

  18. The relationship of bone-tumor-induced spinal cord astrocyte activation and aromatase expression to mechanical hyperalgesia and cold hypersensitivity in intact female and ovariectomized mice.

    PubMed

    Smeester, B A; O'Brien, E E; Michlitsch, K S; Lee, J-H; Beitz, A J

    2016-06-01

    Recently, our group established a relationship between tumor-induced spinal cord astrocyte activation and aromatase expression and the development of bone tumor nociception in male mice. As an extension of this work, we now report on the association of tumor-induced mechanical hyperalgesia and cold hypersensitivity to changes in spinal cord dorsal horn GFAP and aromatase expression in intact (INT) female mice and the effect of ovariectomy on these parameters. Implantation of fibrosarcoma cells produced robust mechanical hyperalgesia in INT animals, while ovariectomized (OVX) females had significantly less mechanical hyperalgesia. Cold hypersensitivity was apparent by post-implantation day 7 in INT and OVX females compared to their saline-injected controls and increased throughout the experiment. The decrease in mechanical hyperalgesia in OVX females was mirrored by significant decreases in spinal astrocyte activity in laminae I-II, III-IV, V-VI and X and aromatase expression in laminae V-VI and X in the dorsal horn of tumor-bearing animals. Administration of the aromatase inhibitor letrozole reduced tumor-induced hyperalgesia in INT females only suggesting that the tumor-induced increase in aromatase expression and its associated increase in spinal estrogen play a role in the development of bone tumor-induced hyperalgesia. Finally, intrathecal (i.t.) administration of 17β-estradiol caused a significant increase in tumor-induced hyperalgesia in INT tumor-bearing females. Since i.t. 17β-estradiol increases tumor pain and ovariectomy significantly decreases tumor pain, as well as spinal aromatase, estrogen may play a critical role in the spinal cord response to the changing tumor environment and the development of tumor-induced nociception. PMID:26995084

  19. Peripheral gene expression profile of mechanical hyperalgesia induced by repeated cold stress in SHRSP5/Dmcr rats.

    PubMed

    Kozaki, Yasuko; Umetsu, Rena; Mizukami, Yukako; Yamamura, Aya; Kitamori, Kazuya; Tsuchikura, Satoru; Ikeda, Katsumi; Yamori, Yukio

    2015-09-01

    Repeated cold stress (RCS) is known to transiently induce functional disorders associated with hypotension and hyperalgesia. In this study, we investigated the effects of RCS (24 and 4 °C alternately at 30-min intervals during the day and 4 °C at night for 2 days, followed by 4 °C on the next 2 consecutive nights) on the thresholds for cutaneous mechanical pain responses and on peripheral expression of "pain-related genes" in SHRSP5/Dmcr rats, which are derived from stroke-prone spontaneously hypertensive rats. To define genes peripherally regulated by RCS, we detected changes in the expression of pain-related genes in dorsal root ganglion cells by PCR-based cDNA subtraction analysis or DNA microarray analysis, and confirmed the changes by RT-PCR. We found significantly changed expression in eight pain-related genes (upregulated: Fyn, St8sia1, and Tac 1; downregulated: Ctsb, Fstl1, Itpr1, Npy, S100a10). At least some of these genes may play key roles in hyperalgesia induced by RCS. PMID:25972297

  20. Pain Modulation by Lignans (Phyllanthin and Hypophyllanthin) and Tannin (Corilagin) Rich Extracts of Phyllanthus amarus in Carrageenan-induced Thermal and Mechanical Chronic Muscle Hyperalgesia.

    PubMed

    Chopade, Atul R; Sayyad, F J

    2015-08-01

    The current study was aimed at evaluating the antihyperalgesic effects of lignans (phyllanthin and hypophyllanthin) and tannin (corilagin) rich three standardized extracts of Phyllanthus amarus in a model of chronic musculoskeletal inflammatory pain. Three percent carrageenan injected in the gastrocnemius muscle produced hyperalgesia to mechanical and heat stimuli ipsilaterally, which spreads to the contralateral side within 7 to 9 days. To investigate the effects on chronic thermal and mechanical hypersensitivity, three extracts of P. amarus in three doses (100, 200, and 400 mg/kg) were administered to animals intraperitoneally from 14th day to 22nd day after intramuscular injection of carrageenan. It was observed that intraperitoneal administrations of Phyllanthus extracts showed antihyperalgesic activity, as they elevated thermal and mechanical threshold, which was supported by histopathological observations along with reduction in prostaglandin E2 (PGE2) concentration. In conclusion, we strongly suggest that the observed antihyperalgesic and antiinflammatory effects of P. amarus in current pain model are mediated via spinal or supraspinal neuronal mechanisms, mainly by inhibition of PGE2. Modulation of chronic muscular inflammation may be due to presence of phytoconstituents like phyllanthin, hypophyllanthin, and corilagin, which offers a promising means for treatment of chronic muscle pain. PMID:25974715

  1. Peripheral G protein-coupled inwardly rectifying potassium (GIRK) channels are involved in delta opioid receptor-mediated anti-hyperalgesia in rat masseter muscle

    PubMed Central

    Chung, Man-Kyo; Cho, Yi Sul; Bae, Young Chul; Lee, Jongseok; Zhang, Xia; Ro, Jin Y.

    2014-01-01

    Background Although the efficacy of peripherally administered opioid has been demonstrated in preclinical and clinical studies, the underlying mechanisms of its anti-hyperalgesic effects are poorly understood. G protein-coupled inwardly rectifying potassium (GIRK) channels are linked to opioid receptors in the brain. However, the role of peripheral GIRK channels in analgesia induced by peripherally administered opioid, especially in trigeminal system, is not clear. Methods Expression of GIRK subunits in rat trigeminal ganglia (TG) was examined with RT-PCR, western blot and immunohistochemistry. Chemical profiles of GIRK expressing neurons in TG were further characterized. Behavioral and Fos experiments were performed to examine the functional involvement of GIRK channels in delta opioid receptor (DOR)-mediated anti-hyperalgesia under an acute myositis condition. Results TG expressed mRNA and proteins for GIRK1 and GIRK2 subunits. Majority of GIRK1- and GIRK2-expressing neurons were non-peptidergic afferents. Inhibition of peripheral GIRK using Tertiapin-Q (TPQ) attenuated anti-nociceptive effects of peripherally administered DOR agonist, DPDPE, on mechanical hypersensitivity in masseter muscle. Furthermore, TPQ attenuated the suppressive effects of peripheral DPDPE on neuronal activation in the subnucleus caudalis of the trigeminal nucleus (Vc) following masseteric injection of capsaicin. Conclusions Our data indicate that peripheral DOR agonist-induced suppression of mechanical hypersensitivity in the masseter muscle involves the activity of peripheral GIRK channels. These results could provide a rationale for developing a novel therapeutic approach using peripheral GIRK channel openers to mimic or supplement the effects of peripheral opioid agonist. PMID:23740773

  2. Sex differences in hypothalamic-mediated tonic norepinephrine release for thermal hyperalgesia in rats.

    PubMed

    Wagner, M; Banerjee, T; Jeong, Y; Holden, J E

    2016-06-01

    Neuropathic pain is treated using serotonin norepinephrine reuptake inhibitors with mixed results. Pain facilitation mediated by α1-adrenoceptors may be involved, but whether norepinephrine (NE) is tonically released is unclear. The aim of this study was to determine whether NE is tonically released from A7 cells following chronic constriction injury (CCI), and if the lateral hypothalamus (LH) plays a role in this release in male and female rats with nociceptive and neuropathic pain types. Neuropathic groups received left CCI while nociceptive groups remained naïve to injury. Fourteen days later, rats were given intrathecal infusion of either the α1-adrenoceptor antagonist WB4101, the α2-adrenoceptor antagonist yohimbine (74μg), or normal saline for control. Paw withdrawal latency (PWL) from a thermal stimulus was measured. The generalized estimated equation method was used for statistical analysis. Nociceptive rats given WB4101 had a PWL significantly longer than saline control (7.89±0.63 vs. 5.87±0.52s), while the PWL of neuropathic rats given WB4101 was 13.20±0.52s compared to 6.78±0.52s for the saline control rats. Yohimbine had no significant effect. Microinjection of cobalt chloride (CoCl) in the A7 catecholamine cell group to prevent synaptic transmission blocked the effect of WB4101 in all groups, supporting the notion that spinally descending A7 cells tonically release NE that contributes to α1-mediated nociceptive facilitation. Microinjection of CoCl into the left LH blocked the effect of WB4101 in nociceptive and neuropathic male rats, but had no effect in female rats of either pain type, suggesting differential innervation. These findings indicate that tonic release of NE acts at pronociceptive α1-adrenoceptors, that this effect is greater in rats with nerve damage, and that, while NE comes primarily from the A7 cell group, LH innervation of the A7 cell group is different between the sexes. PMID:27001177

  3. Morphine and gabapentin decrease mechanical hyperalgesia and escape/avoidance behavior in a rat model of neuropathic pain.

    PubMed

    LaBuda, C J; Fuchs, P N

    2000-08-25

    A behavioral test paradigm that measures the aversive quality of stimulus-evoked pain in an animal model of neuropathic pain (L5 ligation) was tested for sensitivity to (1) different forces (476 and 202 mN) and frequencies (once every 15 or 30 s) of mechanical stimulation to the hyperalgesic paw and (2) different doses of the common antinociceptive compounds morphine (1 and 10 mg/kg) and gabapentin (30 and 90 mg/kg). Compared to non-ligated controls, the greater force (476 mN) and frequency (every 15 s) of mechanical stimulation of the hyperalgesic paw was associated with the greatest degree of escape/avoidance behavior. There was not a significant degree of escape/avoidance behavior at the lowest force (202 mN) and frequency (every 30 s) of mechanical stimulation. Compared to ligated vehicle treated controls, morphine (1 mg/kg) and gabapentin (90 mg/kg) decreased mechanical hyperalgesia and also attenuated the escape/avoidance behavior. The antinociceptive and antiaversive effects were found at doses that did not produce evidence of decreased motor activity. It is concluded that the behavioral test paradigm used to measure the aversiveness of stimulus-evoked nociceptive behavior is sensitive to different degrees of evoked pain and traditional analgesic compounds. PMID:10936696

  4. Galanin-Mediated Behavioural Hyperalgesia from the Dorsomedial Nucleus of the Hypothalamus Involves Two Independent Descending Pronociceptive Pathways

    PubMed Central

    Amorim, Diana; Viisanen, Hanna; Wei, Hong; Almeida, Armando; Pertovaara, Antti; Pinto-Ribeiro, Filipa

    2015-01-01

    Activation of the dorsomedial nucleus of the hypothalamus (DMH) by galanin (GAL) induces behavioural hyperalgesia. Since DMH neurones do not project directly to the spinal cord, we hypothesized that the medullary dorsal reticular nucleus (DRt), a pronociceptive region projecting to the spinal dorsal horn (SDH) and/or the serotoninergic raphe-spinal pathway acting on the spinal 5-HT3 receptor (5HT3R) could relay descending nociceptive facilitation induced by GAL in the DMH. Heat-evoked paw-withdrawal latency (PWL) and activity of SDH neurones were assessed in monoarthritic (ARTH) and control (SHAM) animals after pharmacological manipulations of the DMH, DRt and spinal cord. The results showed that GAL in the DMH and glutamate in the DRt lead to behavioural hyperalgesia in both SHAM and ARTH animals, which is accompanied particularly by an increase in heat-evoked responses of wide-dynamic range neurons, a group of nociceptive SDH neurones. Facilitation of pain behaviour induced by GAL in the DMH was reversed by lidocaine in the DRt and by ondansetron, a 5HT3R antagonist, in the spinal cord. However, the hyperalgesia induced by glutamate in the DRt was not blocked by spinal ondansetron. In addition, in ARTH but not SHAM animals PWL was increased after lidocaine in the DRt and ondansetron in the spinal cord. Our data demonstrate that GAL in the DMH activates two independent descending facilitatory pathways: (i) one relays in the DRt and (ii) the other one involves 5-HT neurones acting on spinal 5HT3Rs. In experimental ARTH, the tonic pain-facilitatory action is increased in both of these descending pathways. PMID:26565961

  5. Nerve growth factor induces facial heat hyperalgesia and plays a role in trigeminal neuropathic pain in rats.

    PubMed

    Dos Reis, Renata C; Kopruszinski, Caroline M; Nones, Carina F M; Chichorro, Juliana G

    2016-09-01

    There is preclinical evidence that nerve growth factor (NGF) contributes toward inflammatory hyperalgesia in the orofacial region, but the mechanisms underlying its hyperalgesic effect as well as its role in trigeminal neuropathic pain require further investigation. This study investigated the ability of NGF to induce facial heat hyperalgesia and the involvement of tyrosine kinase receptor A, transient receptor potential vanilloid 1, and mast cells in NGF pronociceptive effects. In addition, the role of NGF in heat hyperalgesia in a model of trigeminal neuropathic pain was evaluated. NGF injection into the upper lip of naive rats induced long-lasting heat hyperalgesia. Pretreatment with an antibody anti-NGF, antagonists of tyrosine kinase receptor A, and transient receptor potential vanilloid 1 receptors or compound 48/80, to induce mast-cell degranulation, all attenuated NGF-induced hyperalgesia. In a rat model of trigeminal neuropathic pain, local treatment with anti-NGF significantly reduced heat hyperalgesia. In addition, increased NGF levels were detected in the ipsilateral infraorbital nerve branch at the time point that represents the peak of heat hyperalgesia. The results suggest that NGF is a prominent hyperalgesic mediator in the trigeminal system and it may represent a potential therapeutic target for the management of painful orofacial conditions, including trigeminal neuropathic pain. PMID:27392124

  6. Inhibition of endogenous NGF degradation induces mechanical allodynia and thermal hyperalgesia in rats

    PubMed Central

    2013-01-01

    Background We have previously shown a sprouting of sympathetic fibers into the upper dermis of the skin following subcutaneous injection of complete Freund’s adjuvant (CFA) into the hindpaw. This sprouting correlated with an increase in pain-related sensitivity. We hypothesized that this sprouting and pain-related behavior were caused by an increase in nerve growth factor (NGF) levels. In this study, we investigated whether the inhibition of mature NGF degradation, using a matrix metalloproteinase 2 and 9 (MMP-2/9) inhibitor, was sufficient to reproduce a similar phenotype. Results Behavioral tests performed on male Sprague–Dawley rats at 1, 3, 7 and 14 days after intra-plantar MMP-2/9 inhibitor administration demonstrated that acute and chronic injections of the MMP-2/9 inhibitor induced sensitization, in a dose dependent manner, to mechanical, hot and cold stimuli as measured by von Frey filaments, Hargreaves and acetone tests, respectively. Moreover, the protein levels of mature NGF (mNGF) were increased, whereas the levels and enzymatic activity of matrix metalloproteinase 9 were reduced in the glabrous skin of the hind paw. MMP-2/9 inhibition also led to a robust sprouting of sympathetic fibers into the upper dermis but there were no changes in the density of peptidergic nociceptive afferents. Conclusions These findings indicate that localized MMP-2/9 inhibition provokes a pattern of sensitization and fiber sprouting comparable to that previously obtained following CFA injection. Accordingly, the modulation of endogenous NGF levels should be considered as a potential therapeutic target for the management of inflammatory pain associated with arthritis. PMID:23889761

  7. Eccentric Muscle Contraction and Stretching Evoke Mechanical Hyperalgesia and Modulate CGRP and P2X3 Expression in a Functionally Relevant Manner

    PubMed Central

    Dessem, Dean; Ambalavanar, Ranjinidevi; Evancho, Melena; Moutanni, Aicha; Yallampalli, Chandrasekhar; Bai, Guang

    2010-01-01

    Non-invasive, movement-based models were used to investigate muscle pain. In rats, the masseter muscle was rapidly stretched or electrically stimulated during forced lengthening to produce eccentric muscle contractions (EC). Both EC and stretching disrupted scattered myofibers and produced intramuscular plasma extravasation. Pro-inflammatory cytokines (IL-1β, TNF-α, IL-6) and vascular endothelial growth factor (VEGF) were elevated in the masseter 24h following EC. At 48h, neutrophils increased and ED1 macrophages infiltrated myofibers while ED2 macrophages were abundant at 4d. Mechanical hyperalgesia was evident in the ipsilateral head 4h-4d after a single bout of EC and for 7d following multiple bouts (1 bout/d for 4d). Calcitonin gene-related peptide (CGRP) mRNA increased in the trigeminal ganglion 24h following EC while immunoreactive CGRP decreased. By 2d, CGRP-muscle afferent numbers equaled naive numbers implying that CGRP is released following EC and replenished within 2d. EC elevated P2X3 mRNA and increased P2X3-muscle afferent neuron number for 12d while electrical stimulation without muscle contraction altered neither CGRP nor P2X3 mRNA levels. Muscle stretching produced hyperalgesia for 2d whereas contraction alone produced no hyperalgesia. Stretching increased CGRP mRNA at 24h but not CGRP-muscle afferent number at 2–12d. In contrast, stretching significantly increased the number of P2X3-muscle afferent neurons for 12d. The sustained, elevated P2X3 expression evoked by EC and stretching may enhance nociceptor responsiveness to ATP released during subsequent myofiber damage. Movement-based actions such as EC and muscle stretching produce unique tissue responses and modulate neuropeptide and nociceptive receptor expression in a manner particularly relevant to repeated muscle damage. PMID:20207080

  8. Motor Cortex Stimulation Reduces Hyperalgesia in an Animal Model of Central Pain

    PubMed Central

    Lucas, Jessica M; Ji, Yadong; Masri, Radi

    2011-01-01

    Electrical stimulation of the primary motor cortex has been used since 1991 to treat chronic neuropathic pain. Since its inception, motor cortex stimulation (MCS) treatment has had varied clinical outcomes. Until this point, there has not been a systematic study of the stimulation parameters that most effectively treat chronic pain, or of the mechanisms by which MCS relieves pain. Here, using a rodent model of central pain, we perform a systematic study of stimulation parameters used for MCS and investigate the mechanisms by which MCS reduces hyperalgesia. Specifically, we study the role of the inhibitory nucleus zona incerta (ZI) in mediating the analgesic effects of MCS. In animals with mechanical and thermal hyperalgesia, we find that stimulation at 50 µA, 50 Hz, and 300 µs square pulses, for 30 minutes is sufficient to reverse mechanical and thermal hyperalgesia. We also find that stimulation of the ZI mimics the effects of MCS and that reversible inactivation of ZI blocks the effects of MCS. These findings suggest that the reduction of hyperalgesia maybe due to MCS effects on ZI. PMID:21396776

  9. Effect of intraperitoneal administered ginseng total saponins on hyperalgesia induced by repeated intramuscular injection of acidic saline in rats.

    PubMed

    Kim, Won Joong; Kang, Hyun; Kim, Jung Eun; Choi, Geun Joo; Shin, Hwa Yong; Baek, Chong Wha; Jung, Yong Hun; Woo, Young Choel; Kim, Su Hyun; Lee, Jeong Hyuk

    2014-06-01

    The aim of this study was to assess the antinociceptive activity of ginseng total saponins (GTS) on hyperalgesia induced by repeated intramuscular injections of acidic saline in rats and to examine the mechanisms involved. Rats were injected intraperitoneally with a 0.9% saline vehicle or various doses of GTS after the development of hyperalgesia. Rats were then injected with N-methyl-D-aspartate (NMDA) or naloxone 10 min before GTS injection. The mechanical withdrawal threshold (MWT) was assessed with von Frey filaments. The MWT was significantly increased after intraperitoneal injection of 100 mg/kg and 200 mg/kg of GTS when compared with the MWT after the development of hyperalgesia. Injection of GTS with NMDA showed a significant decrease in the MWT when compared with GTS injection. GTS showed an antinociceptive activity against chronic muscle-induced pain, and the effect of GTS may be mediated by NMDA. PMID:24853193

  10. PHARMACOLOGIC TREATMENT OF HYPERALGESIA EXPERIMENTALLY INDUCED BY NUCLEUS PULPOSUS

    PubMed Central

    de Souza Grava, André Luiz; Ferrari, Luiz Fernando; Parada, Carlos Amílcar; Defino, Helton Luiz Aparecido

    2015-01-01

    Objective: To evaluate the effect of anti-inflammatory drugs (dexamethasone, indomethacin, atenolol and indomethacin plus atenolol) and analgesic drugs (morphine) on hyperalgesia experimentally induced by the nucleus pulposus (NP) in contact with the L5 dorsal root ganglion (DRG). Methods: Thirty male Wistar rats of weights ranging from 220 to 250 g were used in the study. Hyperalgesia was induced by means of a fragment of NP removed from the sacrococcygeal region that was placed in contact with the L5 dorsal root ganglion. The 30 animals were divided into experimental groups according to the drug used. The drugs were administered for two weeks after the surgical procedure to induce hyperalgesia. Mechanical and thermal hyperalgesia was evaluated using the paw pressure test, von Frey electronic test and Hargreaves test, over a seven-week period. Results: The greatest reduction of hyperalgesia was observed in the group of animals treated with morphine, followed by dexamethasone, indomethacin and atenolol. Reductions in hyperalgesia were observed after drug administration ceased, except for the group of animals treated with morphine, in which there was an increase in hyperalgesia after discontinuation of the treatment. Conclusion: Hyperalgesia induced by NP contact with the DRG can be reduced through administration of anti-inflammatory and analgesic drugs, but a greater reduction was observed with the administration of dexamethasone. PMID:27026966

  11. Phosphorylation of TRPV1 by cyclin-dependent kinase 5 promotes TRPV1 surface localization, leading to inflammatory thermal hyperalgesia.

    PubMed

    Liu, Jiao; Du, Junxie; Yang, Yanrui; Wang, Yun

    2015-11-01

    Cyclin-dependent kinase 5 (Cdk5) is an important serine/threonine kinase that plays critical roles in many physiological processes. Recently, Cdk5 has been reported to phosphorylate TRPV1 at threonine 407 (Thr-407) in humans (Thr-406 in rats), which enhances the function of TRPV1 channel and promotes thermal hyperalgesia in the complete Freund's adjuvant (CFA)-induced inflammatory pain rats. However, the underlying mechanisms are still unknown. Here, we demonstrate that Cdk5 phosphorylates TRPV1 at Threonine 406 and promotes the surface localization of TRPV1, leading to inflammatory thermal hyperalgesia. The mutation of Thr-406 of TRPV1 to alanine reduced the interaction of TRPV1 with the cytoskeletal elements and decreased the binding of TRPV1 with the motor protein KIF13B, which led to reduced surface distribution of TRPV1. Disrupting the phosphorylation of TRPV1 at Thr-406 dramatically reduced the surface level of TRPV1 in HEK 293 cells after transient expression and the channel function in cultured dorsal root ganglion (DRG) neurons. Notably, intrathecal administration of the interfering peptide against the phosphorylation of Thr-406 alleviated heat hyperalgesia and reduced the surface level of TRPV1 in inflammatory pain rats. Together, these results demonstrate that Cdk5-mediated phosphorylation of TRPV1 at Thr-406 increases the surface level and the function of TRPV1, while the TAT-T406 peptide can effectively attenuate thermal hyperalgesia. Our studies provide a potential therapy for inflammatory pain. PMID:26376215

  12. Sustained Suppression of Hyperalgesia during Latent Sensitization by μ-, δ-, and κ-opioid receptors and α2A Adrenergic Receptors: Role of Constitutive Activity

    PubMed Central

    Walwyn, Wendy M.; Chen, Wenling; Kim, Hyeyoung; Minasyan, Ani; Ennes, Helena S.; McRoberts, James A.

    2016-01-01

    Many chronic pain disorders alternate between bouts of pain and periods of remission. The latent sensitization model reproduces this in rodents by showing that the apparent recovery (“remission”) from inflammatory or neuropathic pain can be reversed by opioid antagonists. Therefore, this remission represents an opioid receptor-mediated suppression of a sustained hyperalgesic state. To identify the receptors involved, we induced latent sensitization in mice and rats by injecting complete Freund's adjuvant (CFA) in the hindpaw. In WT mice, responses to mechanical stimulation returned to baseline 3 weeks after CFA. In μ-opioid receptor (MOR) knock-out (KO) mice, responses did not return to baseline but partially recovered from peak hyperalgesia. Antagonists of α2A-adrenergic and δ-opioid receptors reinstated hyperalgesia in WT mice and abolished the partial recovery from hyperalgesia in MOR KO mice. In rats, antagonists of α2A adrenergic and μ-, δ-, and κ-opioid receptors reinstated hyperalgesia during remission from CFA-induced hyperalgesia. Therefore, these four receptors suppress hyperalgesia in latent sensitization. We further demonstrated that suppression of hyperalgesia by MORs was due to their constitutive activity because of the following: (1) CFA-induced hyperalgesia was reinstated by the MOR inverse agonist naltrexone (NTX), but not by its neutral antagonist 6β-naltrexol; (2) pro-enkephalin, pro-opiomelanocortin, and pro-dynorphin KO mice showed recovery from hyperalgesia and reinstatement by NTX; (3) there was no MOR internalization during remission; (4) MORs immunoprecipitated from the spinal cord during remission had increased Ser375 phosphorylation; and (5) electrophysiology recordings from dorsal root ganglion neurons collected during remission showed constitutive MOR inhibition of calcium channels. SIGNIFICANCE STATEMENT Chronic pain causes extreme suffering to millions of people, but its mechanisms remain to be unraveled. Latent

  13. NSAIDs attenuate hyperalgesia induced by TRP channel activation

    PubMed Central

    Nozadze, Ivliane; Tsiklauri, Nana; Gurtskaia, Gulnaz; Tsagareli, Merab G.

    2016-01-01

    Transient receptor potential (TRP) cation channels have been extensively investigated as targets for analgesic drug discovery. Because some non-steroidal anti-inflammatory drugs (NSAIDs) are structural analogs of prostaglandins (mediators of inflammation) and NSAIDs attenuate heat nociception and mechanical allodynia in models of inflammatory and neuropathic pain, we examined three widely used NSAIDs (diclofenac, ketorolac, and xefocam) on the activation of TRPA1 and TRPV1 channels using thermal paw withdrawal (Hargreaves) test and mechanical paw withdrawal (von Frey) test in male rats. Thermal withdrawal latencies and mechanical thresholds for both hind paws were obtained with 5, 15, 30, 45, 60, and 120 min intraplantar post-injection of TRPA1 agonizts, allyl isothiocyanate (AITC) (a natural compound of mustard oil) and cinnamaldehyde (CA), and TRPV1 agonist capsaicin or vehicle. Twenty minutes prior to the start of the experiment with TRP agonizts, diclofenac, ketorolac or xefocam were pre-injected in the same hindpaw and animals were examined by these two tests. After pretreatment of all three NSAIDs in the ipsilateral (injected) hindpaw that produced strong antinociceptive effects, AITC, CA, and capsaicin caused significant decreases in latency of the thermal withdrawal reflex compared with vehicle or the contralateral hindpaw. The same findings were observed for the paw withdrawal threshold. In approximately 30 min the effects of CA, AITC, and capsaicin returned to baseline. The data are different from our previous evidence, where TRPA1 agonizts AITC and CA and TRPV1 agonist capsaicin produced hyperalgesia for nearly 2 h and resulted in facilitation of these withdrawal reflexes (Tsagareli et al., 2010, 2013). Thus, our data showing that NSAIDs suppress thermal and mechanical hyperalgesia following TRP activation could presumably due to inactivation or desensitization of TRPA1 and TRPV1 channels by NSAIDs. PMID:26909384

  14. NSAIDs attenuate hyperalgesia induced by TRP channel activation.

    PubMed

    Nozadze, Ivliane; Tsiklauri, Nana; Gurtskaia, Gulnaz; Tsagareli, Merab G

    2016-03-01

    Transient receptor potential (TRP) cation channels have been extensively investigated as targets for analgesic drug discovery. Because some non-steroidal anti-inflammatory drugs (NSAIDs) are structural analogs of prostaglandins (mediators of inflammation) and NSAIDs attenuate heat nociception and mechanical allodynia in models of inflammatory and neuropathic pain, we examined three widely used NSAIDs (diclofenac, ketorolac, and xefocam) on the activation of TRPA1 and TRPV1 channels using thermal paw withdrawal (Hargreaves) test and mechanical paw withdrawal (von Frey) test in male rats. Thermal withdrawal latencies and mechanical thresholds for both hind paws were obtained with 5, 15, 30, 45, 60, and 120 min intraplantar post-injection of TRPA1 agonizts, allyl isothiocyanate (AITC) (a natural compound of mustard oil) and cinnamaldehyde (CA), and TRPV1 agonist capsaicin or vehicle. Twenty minutes prior to the start of the experiment with TRP agonizts, diclofenac, ketorolac or xefocam were pre-injected in the same hindpaw and animals were examined by these two tests. After pretreatment of all three NSAIDs in the ipsilateral (injected) hindpaw that produced strong antinociceptive effects, AITC, CA, and capsaicin caused significant decreases in latency of the thermal withdrawal reflex compared with vehicle or the contralateral hindpaw. The same findings were observed for the paw withdrawal threshold. In approximately 30 min the effects of CA, AITC, and capsaicin returned to baseline. The data are different from our previous evidence, where TRPA1 agonizts AITC and CA and TRPV1 agonist capsaicin produced hyperalgesia for nearly 2 h and resulted in facilitation of these withdrawal reflexes (Tsagareli et al., 2010, 2013). Thus, our data showing that NSAIDs suppress thermal and mechanical hyperalgesia following TRP activation could presumably due to inactivation or desensitization of TRPA1 and TRPV1 channels by NSAIDs. PMID:26909384

  15. Patterns of hyperalgesia in complex regional pain syndrome.

    PubMed

    Sieweke, N; Birklein, F; Riedl, B; Neundörfer, B; Handwerker, H O

    1999-03-01

    Complex regional pain syndrome (CRPS) is characterized by a triad of sensory, motor and autonomic dysfunctions, with long-standing pain and temperature differences of the affected and contralateral limb as predominant symptoms. The pathogenesis of the disorder still remains unclear. Among the main hypotheses of an underlying pathophysiology we find inflammatory processes and dysfunction of the sympathetic nervous system. Whether the main site of dysfunction is found centrally or peripherally is not known. With psychophysical methods we studied patterns of hyperalgesia to obtain a better understanding of the neuropathic pain component in CRPS. Forty patients in an acute phase of CRPS and a median duration of the disease of 10 weeks, were included in the study. Hyperalgesia to heat was tested with a thermode providing feedback-controlled temperature increases. Two forms of mechanical hyperalgesia were examined: phasic mechanical stimuli by using a custom-made impact stimulator for the determination of individual pain thresholds, tonic mechanical stimuli were applied using a pinch-device. Additionally a 'wind-up' paradigm was used to study a pain phenomenon of presumed central origin: a defined impact stimulus was given once and five times in repetition. A subpopulation of patients was reevaluated for mechanical hyperalgesia after i.v. injection of 500 mg acetyl-salicylic acid. Hyperalgesia to heat was insignificant. We found, however, a marked mechanical hyperalgesia to phasic impact stimuli (P < 0.005), whereas, static stimulation (squeezing skin folds) results were insignificant again. Wind-up related pain was also significantly enhanced in the affected limb (P < 0.02). The anti-inflammatory agent had no effect. These results indicate a non-inflammatory pathogenesis in CRPS presumably central in origin. PMID:10204729

  16. Fear of pain potentiates nocebo hyperalgesia.

    PubMed

    Aslaksen, Per M; Lyby, Peter S

    2015-01-01

    Nocebo hyperalgesia has received sparse experimental attention compared to placebo analgesia. The aim of the present study was to investigate if personality traits and fear of pain could predict experimental nocebo hyperalgesia. One hundred and eleven healthy volunteers (76 females) participated in an experimental study in which personality traits and fear of pain were measured prior to induction of thermal heat pain. Personality traits were measured by the Big-Five Inventory-10. Fear of pain was measured by the Fear of Pain Questionnaire III. Heat pain was induced by a PC-controlled thermode. Pain was measured by a computerized visual analog scale. Stress levels during the experiment were measured by numerical rating scales. The participants were randomized to a Nocebo group or to a no-treatment Natural History group. The results revealed that pain and stress levels were significantly higher in the Nocebo group after nocebo treatment. Mediation analysis showed that higher levels of the Fear of Pain Questionnaire III factor "fear of medical pain" significantly increased stress levels after nocebo treatment and that higher stress levels were associated with increased nocebo hyperalgesic responses. There were no significant associations between any of the personality factors and the nocebo hyperalgesic effect. The results from the present study suggest that dispositional fear of pain might be a useful predictor for nocebo hyperalgesia and emotional states concomitant with expectations of increased pain. Furthermore, measurement of traits that are specific to pain experience is probably better suited for prediction of nocebo hyperalgesic responses compared to broad measures of personality. PMID:26491370

  17. Fear of pain potentiates nocebo hyperalgesia

    PubMed Central

    Aslaksen, Per M; Lyby, Peter S

    2015-01-01

    Nocebo hyperalgesia has received sparse experimental attention compared to placebo analgesia. The aim of the present study was to investigate if personality traits and fear of pain could predict experimental nocebo hyperalgesia. One hundred and eleven healthy volunteers (76 females) participated in an experimental study in which personality traits and fear of pain were measured prior to induction of thermal heat pain. Personality traits were measured by the Big-Five Inventory-10. Fear of pain was measured by the Fear of Pain Questionnaire III. Heat pain was induced by a PC-controlled thermode. Pain was measured by a computerized visual analog scale. Stress levels during the experiment were measured by numerical rating scales. The participants were randomized to a Nocebo group or to a no-treatment Natural History group. The results revealed that pain and stress levels were significantly higher in the Nocebo group after nocebo treatment. Mediation analysis showed that higher levels of the Fear of Pain Questionnaire III factor “fear of medical pain” significantly increased stress levels after nocebo treatment and that higher stress levels were associated with increased nocebo hyperalgesic responses. There were no significant associations between any of the personality factors and the nocebo hyperalgesic effect. The results from the present study suggest that dispositional fear of pain might be a useful predictor for nocebo hyperalgesia and emotional states concomitant with expectations of increased pain. Furthermore, measurement of traits that are specific to pain experience is probably better suited for prediction of nocebo hyperalgesic responses compared to broad measures of personality. PMID:26491370

  18. Inflammatory Signals Enhance Piezo2-Mediated Mechanosensitive Currents

    PubMed Central

    Dubin, Adrienne E.; Schmidt, Manuela; Mathur, Jayanti; Petrus, Matthew J.; Xiao, Bailong; Coste, Bertrand; Patapoutian, Ardem

    2012-01-01

    Summary Heightened nociceptor function caused by inflammatory mediators such as bradykinin contributes to increased pain perception (hyperalgesia) to noxious mechanical and thermal stimuli. While sensitization of the heat transducer TRPV1 largely subserves thermal hyperalgesia, cellular mechanisms underlying mechanical hyperalgesia have been elusive. The role of the mechanically-activated (MA) channel piezo2 (known as FAM38B) present in mammalian sensory neurons is unknown. We test the hypothesis that piezo2 activity is enhanced by bradykinin, an algogenic peptide that induces mechanical hyperalgesia within minutes. Piezo2 current amplitude is increased and inactivation slowed by bradykinin 2 receptor (BDKRB2) activation in heterologous expression systems. Protein Kinase A (PKA) and Protein Kinase C (PKC) agonists enhance piezo2 activity. BDKRB2-mediated effects are abolished by PKA and PKC inhibitors. Finally, piezo2-dependent MA currents in a class of native sensory neurons are enhanced 8-fold by bradykinin via PKA and PKC. Thus, piezo2 sensitization may contribute to PKA- and PKC-mediated mechanical hyperalgesia. PMID:22921401

  19. ASIC3 Is Required for Development of Fatigue-Induced Hyperalgesia.

    PubMed

    Gregory, Nicholas S; Brito, Renan G; Fusaro, Maria Cláudia G Oliveira; Sluka, Kathleen A

    2016-03-01

    An acute bout of exercise can exacerbate pain, hindering participation in regular exercise and daily activities. The mechanisms underlying pain in response to acute exercise are poorly understood. We hypothesized that proton accumulation during muscle fatigue activates acid-sensing ion channel 3 (ASIC3) on muscle nociceptors to produce hyperalgesia. We investigated the role of ASIC3 using genetic and pharmacological approaches in a model of fatigue-enhanced hyperalgesia. This model uses two injections of pH 5.0 saline into muscle in combination with an electrically induced fatigue of the same muscle just prior to the second injection of acid to induce mechanical hyperalgesia. We show a significant decrease in muscle force and decrease in muscle pH after 6 min of electrical stimulation. Genetic deletion of ASIC3 using knockout mice and pharmacological blockade of ASIC3 with APETx2 in muscle prevents the fatigue-enhanced hyperalgesia. However, ASIC3(-/-) mice and APETx2 have no effect on the fatigue response. Genetic deletion of ASIC3 in primary afferents innervating muscle using an HSV-1 expressing microRNA (miRNA) to ASIC3 surprisingly had no effect on the development of the hyperalgesia. Muscle fatigue increased the number of macrophages in muscle, and removal of macrophages from muscle with clodronate liposomes prevented the development of fatigue-enhanced hyperalgesia. Thus, these data suggest that fatigue reduces pH in muscle that subsequently activates ASIC3 on macrophages to enhance hyperalgesia to muscle insult. PMID:25577172

  20. Minocycline, a microglial inhibitor, blocks spinal CCL2-induced heat hyperalgesia and augmentation of glutamatergic transmission in substantia gelatinosa neurons

    PubMed Central

    2014-01-01

    Background Several lines of evidence suggest that CCL2 could initiate the hyperalgesia of neuropathic pain by causing central sensitization of spinal dorsal horn neurons and facilitating nociceptive transmission in the spinal dorsal horn. The cellular and molecular mechanisms by which CCL2 enhances spinal pain transmission and causes hyperalgesia remain unknown. The substantia gelatinosa (lamina II) of the spinal dorsal horn plays a critical role in nociceptive transmission. An activated spinal microglia, which is believed to release pro-inflammatory cytokines including TNF-α, plays an important role in the development of neuropathic pain, and CCL2 is a key mediator for spinal microglia activation. In the present study, we tested the hypothesis that spinal CCL2 causes the central sensitization of substantia gelatinosa neurons and enhances spinal nociceptive transmission by activating the spinal microglia and augmenting glutamatergic transmission in lamina II neurons. Methods CCL2 was intrathecally administered to 2-month-old male rats. An intrathecal injection of CCL2 induced heat hyperalgesia, which was assessed using the hot plate test. Whole-cell voltage-clamp recordings substantia gelatinosa neurons in spinal cord slices were performed to record glutamatergic excitatory postsynaptic currents (EPSCs) and GABAergic inhibitory postsynaptic currents (IPSCs). Results The hot plate test showed that 1 day after the intrathecal injection of CCL2 (1 μg), the latency of hind-paw withdrawal caused by a heat stimulus was significantly reduced in rats. One day after the intrathecal administration of CCL2, the amplitude of the evoked glutamatergic EPSCs and the frequency of spontaneous glutamatergic miniature EPSCs (mEPSCs) were significantly increased in outer lamina II neurons. Intrathecal co-injection of minocycline, a specific inhibitor of microglial activation, and CCL2 blocked the CCL2-induced reduction in the latency of hind-paw withdrawal and thermal hyperalgesia

  1. The role of keratinocyte-derived chemokine (KC) on hyperalgesia caused by peripheral nerve injury in mice.

    PubMed

    Manjavachi, Marianne Neves; Costa, Robson; Quintão, Nara Lins; Calixto, João B

    2014-04-01

    Chemokines are associated with both inflammatory and immune responses and play an important role in the pathophysiological process associated with neuropathic pain following peripheral nerve injury. Here, we investigated the involvement of peripheral keratinocyte-derived chemokine (KC) in the pathogenesis of neuropathic pain induced by the partial ligation of the sciatic nerve (PLSN) in mice. PLSN increased KC levels and its mRNA in both the sciatic nerve and spinal cord when compared with sham-operated mice. In addition, PLSN-induced mechanical and thermal hyperalgesia was prevented by systemic (i.v.) treatment with anti-KC antibody either at the time of surgery or on the 4th day after surgery. Also, intrathecal (i.t.) injection of anti-KC antibody prevented mechanical hyperalgesia induced by PLSN when administered at the time of surgery or on the 4th day after surgery. Importantly, the intraneural (i.n.) injection of KC in the mouse sciatic nerve elicited long-lasting mechanical hyperalgesia, which was prevented by the selective CXCR2 antagonist SB225002. The established mechanical hyperalgesia induced by KC was expressively reduced by the treatment with gabapentin, a drug widely used to treat chronic pain in humans. Intraneural KC injection also caused neutrophil migration into the mouse sciatic nerve and the depletion of neutrophils, by pre-treating animals with vinblastine, significantly reduced KC-induced mechanical hyperalgesia. Similar results were obtained for the pre-treatment with indomethacin, a non-selective COX inhibitor. We also demonstrated an increased level of cytokines (IL-1β, IL-6, and MCP-1, but not TNF-α) after i.n. injection of KC in the mouse sciatic nerve. Together, these findings suggest a role for KC in the development of neuropathic pain in mice by attracting neutrophils to the injured site and increasing the production of proinflammatory mediators. Therefore, strategies to inhibit the action or the release of this chemokine could

  2. Dose response of tramadol and its combination with paracetamol in UVB induced hyperalgesia.

    PubMed

    Ortner, C M; Steiner, I; Margeta, K; Schulz, M; Gustorff, B

    2012-04-01

    Combining tramadol with paracetamol is an established analgesic treatment strategy. However, dosing and differential effects on peripheral and central hyperalgesia are still to be determined. After Ethics Committee approval, 32 volunteers have been included in this 2 phased, double blinded, placebo controlled, cross-over study. A defined small skin area was irradiated with a UVB source inducing hyperalgesia. Twenty-four hours after irradiation, heat pain-, cold pain threshold (HPPT, CPPT), mechanical pain sensitivity to pin prick (MPS) in the area of pin prick hyperalgesia (AsH) and MPS in the sunburn were determined. In phase I, measurements have been repeated 30 min after receiving cumulative 0.3, 0.6 and 1 mg/kg of intravenous (i.v.) tramadol or active placebo. Only at 1 mg/kg tramadol and solely for MPS in the sunburn a reduction to placebo could be demonstrated (p = 0.024). Accordingly in phase II, the trial has been repeated using 1 mg/kg tramadol and paracetamol or placebo in a cumulative i.v. dose of 330, 660 and 990 mg. Now the addition of 330 mg paracetamol to tramadol reduced thermal hyperalgesia by 1.15 °C (CI 0.55; 1.76). This effect, however, did not increase with higher doses. Tramadol showed week anti-hyperalgesia reducing CPPT, MPS and AsH compared to baseline measurements (p < 0.05). Paracetamol also reduced secondary hyperalgesia, but no combination effect with tramadol could be shown. We conclude, in inflammatory hyperalgesia tramadol alone exerts only weak anti-hyperalgesia. Even adding a small dose paracetamol enhances thermal anti-hyperalgesia. PMID:22396084

  3. Intrathecal AAV serotype 9-mediated delivery of shRNA against TRPV1 attenuates thermal hyperalgesia in a mouse model of peripheral nerve injury.

    PubMed

    Hirai, Takashi; Enomoto, Mitsuhiro; Kaburagi, Hidetoshi; Sotome, Shinichi; Yoshida-Tanaka, Kie; Ukegawa, Madoka; Kuwahara, Hiroya; Yamamoto, Mariko; Tajiri, Mio; Miyata, Haruka; Hirai, Yukihiko; Tominaga, Makoto; Shinomiya, Kenichi; Mizusawa, Hidehiro; Okawa, Atsushi; Yokota, Takanori

    2014-02-01

    Gene therapy for neuropathic pain requires efficient gene delivery to both central and peripheral nervous systems. We previously showed that an adenoassociated virus serotype 9 (AAV9) vector expressing short-hairpin RNA (shRNA) could suppress target molecule expression in the dorsal root ganglia (DRG) and spinal cord upon intrathecal injection. To evaluate the therapeutic potential of this approach, we constructed an AAV9 vector encoding shRNA against vanilloid receptor 1 (TRPV1), which is an important target gene for acute pain, but its role in chronic neuropathic pain remains unclear. We intrathecally injected it into the subarachnoid space at the upper lumbar spine of mice 3 weeks after spared nerve injury (SNI). Delivered shTRPV1 effectively suppressed mRNA and protein expression of TRPV1 in the DRG and spinal cord, and it attenuated nerve injury-induced thermal allodynia 10-28 days after treatment. Our study provides important evidence for the contribution of TRPV1 to thermal hypersensitivity in neuropathic pain and thus establishes intrathecal AAV9-mediated gene delivery as an investigative and potentially therapeutic platform for the nervous system. PMID:24322332

  4. Dexamethasone as Adjuvant to Bupivacaine Prolongs the Duration of Thermal Antinociception and Prevents Bupivacaine-Induced Rebound Hyperalgesia via Regional Mechanism in a Mouse Sciatic Nerve Block Model

    PubMed Central

    An, Ke; Elkassabany, Nabil M.; Liu, Jiabin

    2015-01-01

    Background Dexamethasone has been studied as an effective adjuvant to prolong the analgesia duration of local anesthetics in peripheral nerve block. However, the route of action for dexamethasone and its potential neurotoxicity are still unclear. Methods A mouse sciatic nerve block model was used. The sciatic nerve was injected with 60ul of combinations of various medications, including dexamethasone and/or bupivacaine. Neurobehavioral changes were observed for 2 days prior to injection, and then continuously for up to 7 days after injection. In addition, the sciatic nerves were harvested at either 2 days or 7 days after injection. Toluidine blue dyeing and immunohistochemistry test were performed to study the short-term and long-term histopathological changes of the sciatic nerves. There were six study groups: normal saline control, bupivacaine (10mg/kg) only, dexamethasone (0.5mg/kg) only, bupivacaine (10mg/kg) combined with low-dose (0.14mg/kg) dexamethasone, bupivacaine (10mg/kg) combined with high-dose (0.5mg/kg) dexamethasone, and bupivacaine (10mg/kg) combined with intramuscular dexamethasone (0.5mg/kg). Results High-dose perineural dexamethasone, but not systemic dexamethasone, combined with bupivacaine prolonged the duration of both sensory and motor block of mouse sciatic nerve. There was no significant difference on the onset time of the sciatic nerve block. There was “rebound hyperalgesia” to thermal stimulus after the resolution of plain bupivacaine sciatic nerve block. Interestingly, both low and high dose perineural dexamethasone prevented bupivacaine-induced hyperalgesia. There was an early phase of axon degeneration and Schwann cell response as represented by S-100 expression as well as the percentage of demyelinated axon and nucleus in the plain bupivacaine group compared with the bupivacaine plus dexamethasone groups on post-injection day 2, which resolved on post-injection day 7. Furthermore, we demonstrated that perineural dexamethasone

  5. Mu Opioid Splice Variant MOR-1K Contributes to the Development of Opioid-Induced Hyperalgesia

    PubMed Central

    Oladosu, Folabomi A.; Conrad, Matthew S.; O’Buckley, Sandra C.; Rashid, Naim U.; Slade, Gary D.; Nackley, Andrea G.

    2015-01-01

    Background A subset of the population receiving opioids for the treatment of acute and chronic clinical pain develops a paradoxical increase in pain sensitivity known as opioid-induced hyperalgesia. Given that opioid analgesics are one of few treatments available against clinical pain, it is critical to determine the key molecular mechanisms that drive opioid-induced hyperalgesia in order to reduce its prevalence. Recent evidence implicates a splice variant of the mu opioid receptor known as MOR-1K in the emergence of opioid-induced hyperalgesia. Results from human genetic association and cell signaling studies demonstrate that MOR-1K contributes to decreased opioid analgesic responses and produces increased cellular activity via Gs signaling. Here, we conducted the first study to directly test the role of MOR-1K in opioid-induced hyperalgesia. Methods and Results In order to examine the role of MOR-1K in opioid-induced hyperalgesia, we first assessed pain responses to mechanical and thermal stimuli prior to, during, and following chronic morphine administration. Results show that genetically diverse mouse strains (C57BL/6J, 129S6, and CXB7/ByJ) exhibited different morphine response profiles with corresponding changes in MOR-1K gene expression patterns. The 129S6 mice exhibited an analgesic response correlating to a measured decrease in MOR-1K gene expression levels, while CXB7/ByJ mice exhibited a hyperalgesic response correlating to a measured increase in MOR-1K gene expression levels. Furthermore, knockdown of MOR-1K in CXB7/ByJ mice via chronic intrathecal siRNA administration not only prevented the development of opioid-induced hyperalgesia, but also unmasked morphine analgesia. Conclusions These findings suggest that MOR-1K is likely a necessary contributor to the development of opioid-induced hyperalgesia. With further research, MOR-1K could be exploited as a target for antagonists that reduce or prevent opioid-induced hyperalgesia. PMID:26270813

  6. Traumatic Stress Promotes Hyperalgesia via Corticotropin-Releasing Factor-1 Receptor (CRFR1) Signaling in Central Amygdala.

    PubMed

    Itoga, Christy A; Roltsch Hellard, Emily A; Whitaker, Annie M; Lu, Yi-Ling; Schreiber, Allyson L; Baynes, Brittni B; Baiamonte, Brandon A; Richardson, Heather N; Gilpin, Nicholas W

    2016-09-01

    Hyperalgesia is an exaggerated response to noxious stimuli produced by peripheral or central plasticity. Stress modifies nociception, and humans with post-traumatic stress disorder (PTSD) exhibit co-morbid chronic pain and amygdala dysregulation. Predator odor stress produces hyperalgesia in rodents. Systemic blockade of corticotropin-releasing factor (CRF) type 1 receptors (CRFR1s) reduces stress-induced thermal hyperalgesia. We hypothesized that CRF-CRFR1 signaling in central amygdala (CeA) mediates stress-induced hyperalgesia in rats with high stress reactivity. Adult male Wistar rats were exposed to predator odor stress in a conditioned place avoidance paradigm and indexed for high (Avoiders) and low (Non-Avoiders) avoidance of predator odor-paired context, or were unstressed Controls. Rats were tested for the latency to withdraw hindpaws from thermal stimuli (Hargreaves test). We used pharmacological, molecular, and immunohistochemical techniques to assess the role of CRF-CRFR1 signaling in CeA in stress-induced hyperalgesia. Avoiders exhibited higher CRF peptide levels in CeA that did not appear to be locally synthesized. Intra-CeA CRF infusion mimicked stress-induced hyperalgesia. Avoiders exhibited thermal hyperalgesia that was reversed by systemic or intra-CeA injection of a CRFR1 antagonist. Finally, intra-CeA infusion of tetrodotoxin produced thermal hyperalgesia in unstressed rats and blocked the anti-hyperalgesic effect of systemic CRFR1 antagonist in stressed rats. These data suggest that rats with high stress reactivity exhibit hyperalgesia that is mediated by CRF-CRFR1 signaling in CeA. PMID:27013358

  7. Spatial and temporal aspects of muscle hyperalgesia induced by nerve growth factor in humans.

    PubMed

    Andersen, Helle; Arendt-Nielsen, Lars; Svensson, Peter; Danneskiold-Samsøe, Bente; Graven-Nielsen, Thomas

    2008-11-01

    Intramuscular injection of nerve growth factor (NGF) has been shown to induce long-term sensitisation and time-dependent hyperalgesia indicating potential involvement of both central and peripheral pain mechanisms. This double-blind placebo-controlled study was designed to describe the spatial distribution of muscle hyperalgesia over time (immediately after, 3 h, 1, 4, 7 and 21 days) after injecting NGF (5 mug) into the tibialis anterior (TA) muscle, to explore possibly involved central pain mechanisms and to investigate the effect of gender on development of hyperalgesia. Totally 20 healthy volunteers (10 men and 10 women) participated in the study. An isotonic saline injection into the contralateral TA muscle served as a control condition for the NGF injection. Pressure pain thresholds (PPT) were used to test for muscle hyperalgesia along the TA (seven sites) muscle at the extensor digitorum longus and at the web between 1st and 2nd metatarsal (central involvement). One day after the NGF/control injections, hypertonic saline (0.5 ml, 5.8%) was injected into the left and right TA to study the pain response to chemical stimulation of the hyperalgesic muscle tissue. Scores on a modified Likert scale were used to assess soreness during muscle function. An area of hyperalgesia was observed locally at the injected site 3 h after injection of NGF, which expanded both proximally and distally on day 1; this effect subsided on day 4. Decreased PPT was also found between 1st and 2nd metatarsal on day 1. Hypertonic saline evoked more pain in men when injected in the NGF treated TA compared to the control leg. Injection of NGF increased muscle soreness during muscle activity for 7 days. In this material there was no gender effect of NGF-induced muscle hyperalgesia. The expansion of muscle hyperalgesia to distant areas indicates that central mechanisms are involved. PMID:18813917

  8. Suckling and sucrose ingestion suppress persistent hyperalgesia and spinal Fos expression after forepaw inflammation in infant rats.

    PubMed

    Ren, K; Blass, E M; Zhou, Q; Dubner, R

    1997-02-18

    Sweet taste and nonnutritive suckling produce analgesia to transient noxious stimuli in infant rats and humans. The present study evaluated the pain-modulating effects of sucrose and suckling in a rat model of persistent pain and hyperalgesia that mimics the response to tissue injury in humans. Fore- and hindpaw withdrawal latencies from a 30 degrees or 48 degrees C brass stylus were determined in 10-day-old rats following paw inflammation induced by complete Freund's adjuvant (CFA; 1:1 injected s.c. in a 0.01 ml volume). CFA markedly decreased escape latencies to both 48 degrees and 30 degrees C stimulation, thereby demonstrating thermal hyperalgesia and mechanical allodynia. The combination of nonnutritive suckling and sucrose (7.5%, 0.01-0.06 ml/min) infusion markedly increased escape latencies to forepaw stimulation in both CFA-treated and control rats. In contrast, intraoral sucrose and suckling did not increase hindpaw withdrawal latencies in either control or CFA-inflamed rats. The effect was specific to sweet taste because neither water nor isotonic saline infusion affected forepaw escape latencies. Parallel findings were obtained for CFA-induced Fos-like immunoreactivity (Fos-LI), a marker of neuronal activation. Fos-LI was selectively induced in cervical and lumbar regions ipsilateral to forepaw and hindpaw inflammation, respectively. Suckling-sucrose treatment significantly reduced Fos-LI at the cervical but not at the lumbar regions. These findings demonstrate: (i) the development of persistent pain and hyperalgesia in 10-day-old rats that can be attenuated by endogenous pain-modulating systems activated by taste and nonnutritive suckling; (ii) the mediation of the sucrose-suckling analgesia and antihyperalgesia at the spinal level; and (iii) a differential rostrocaudal maturation of descending pain-modulating systems to the spinal cord of 10-day-old rats. These findings may provide new clinical approaches for engaging endogenous analgesic mechanisms in

  9. Mapping the Binding Site of TRPV1 on AKAP79: Implications for Inflammatory Hyperalgesia

    PubMed Central

    Stott, Katherine; McNaughton, Peter A.

    2014-01-01

    Inflammation causes hyperalgesia, an enhanced sensitivity to noxious stimuli. Transient receptor potential vanilloid 1 (TRPV1), a thermo-TRP ion channel activated by painful levels of heat, is an important contributor because hyperalgesia is reduced when TRPV1 is either genetically deleted or pharmacologically blocked. Inflammatory mediators such as prostaglandin-E2 or bradykinin cause hyperalgesia by activating cellular kinases that phosphorylate TRPV1, a process that has recently been shown to rely on a scaffolding protein, AKAP79, to target the kinases to TRPV1. Here we use Förster resonance energy transfer, immunoprecipitation, and TRPV1 membrane trafficking experiments to identify a key region on AKAP79, between amino acids 326–336, which is responsible for its interaction with TRPV1. A peptide identical to this domain inhibited sensitization of TRPV1 in vitro, and when covalently linked to a TAT peptide to promote uptake across the cell membrane the peptide inhibited in vivo inflammatory hyperalgesia in mice. Critically, it did so without affecting pain thresholds in the absence of inflammation. These results suggest that antagonizing the TRPV1–AKAP79 interaction will be a useful strategy for inhibiting inflammatory hyperalgesia. PMID:23699529

  10. TRPA1 receptor stimulation by hydrogen peroxide is critical to trigger hyperalgesia and inflammation in a model of acute gout.

    PubMed

    Trevisan, Gabriela; Hoffmeister, Carin; Rossato, Mateus Fortes; Oliveira, Sara Marchesan; Silva, Mariane Arnoldi; Silva, Cássia Regina; Fusi, Camilla; Tonello, Raquel; Minocci, Daiana; Guerra, Gustavo Petri; Materazzi, Serena; Nassini, Romina; Geppetti, Pierangelo; Ferreira, Juliano

    2014-07-01

    Acute gout attacks produce severe joint pain and inflammation associated with monosodium urate (MSU) crystals leading to oxidative stress production. The transient potential receptor ankyrin 1 (TRPA1) is expressed by a subpopulation of peptidergic nociceptors and, via its activation by endogenous reactive oxygen species, including hydrogen peroxide (H2O2), contributes to pain and neurogenic inflammation. The aim of this study was to investigate the role of TRPA1 in hyperalgesia and inflammation in a model of acute gout attack in rodents. Inflammatory parameters and mechanical hyperalgesia were measured in male Wistar rats and in wild-type (Trpa1(+/+)) or TRPA1-deficient (Trpa1(-/-)) male mice. Animals received intra-articular (ia, ankle) injection of MSU. The role of TRPA1 was assessed by receptor antagonism, gene deletion or expression, sensory fiber defunctionalization, and calcitonin gene-related peptide (CGRP) release. We found that nociceptor defunctionalization, TRPA1 antagonist treatment (via ia or oral administration), and Trpa1 gene ablation abated hyperalgesia and inflammatory responses (edema, H2O2 generation, interleukin-1β release, and neutrophil infiltration) induced by ia MSU injection. In addition, we showed that MSU evoked generation of H2O2 in synovial tissue, which stimulated TRPA1 producing CGRP release and plasma protein extravasation. The MSU-elicited responses were also reduced by the H2O2-detoxifying enzyme catalase and the reducing agent dithiothreitol. TRPA1 activation by MSU challenge-generated H2O2 mediates the entire inflammatory response in an acute gout attack rodent model, thus strengthening the role of the TRPA1 receptor and H2O2 production as potential targets for treatment of acute gout attacks. PMID:24780252

  11. Mechanisms of platelet-mediated liver regeneration.

    PubMed

    Lisman, Ton; Porte, Robert J

    2016-08-01

    Platelets have multiple functions beyond their roles in thrombosis and hemostasis. Platelets support liver regeneration, which is required after partial hepatectomy and acute or chronic liver injury. Although it is widely assumed that platelets stimulate liver regeneration by local excretion of mitogens stored within platelet granules, definitive evidence for this is lacking, and alternative mechanisms deserve consideration. In-depth knowledge of mechanisms of platelet-mediated liver regeneration may lead to new therapeutic strategies to treat patients with failing regenerative responses. PMID:27297793

  12. Mechanisms of Immune-Mediated Liver Injury

    PubMed Central

    Adams, David H.; Ju, Cynthia; Ramaiah, Shashi K.; Uetrecht, Jack; Jaeschke, Hartmut

    2010-01-01

    Hepatic inflammation is a common finding during a variety of liver diseases including drug-induced liver toxicity. The inflammatory phenotype can be attributed to the innate immune response generated by Kupffer cells, monocytes, neutrophils, and lymphocytes. The adaptive immune system is also influenced by the innate immune response leading to liver damage. This review summarizes recent advances in specific mechanisms of immune-mediated hepatotoxicity and its application to drug-induced liver injury. Basic mechanisms of activation of lymphocytes, macrophages, and neutrophils and their unique mechanisms of recruitment into the liver vasculature are discussed. In particular, the role of adhesion molecules and various inflammatory mediators in this process are explored. In addition, the authors describe mechanisms of liver cell damage by these inflammatory cells and critically evaluate the functional significance of each cell type for predictive and idiosyncratic drug-induced liver injury. It is expected that continued advances in our understanding of immune mechanisms of liver injury will lead to an earlier detection of the hepatotoxic potential of drugs under development and to an earlier identification of susceptible individuals at risk for predictive and idiosyncratic drug toxicities. PMID:20071422

  13. Central activation of TRPV1 and TRPA1 by novel endogenous agonists contributes to mechanical allodynia and thermal hyperalgesia after burn injury.

    PubMed

    Green, Dustin; Ruparel, Shivani; Gao, Xiaoli; Ruparel, Nikita; Patil, Mayur; Akopian, Armen; Hargreaves, Kenneth

    2016-01-01

    The primary complaint of burn victims is an intense, often devastating spontaneous pain, with persistence of mechanical and thermal allodynia. The transient receptor potential channels, TRPV1 and TRPA1, are expressed by a subset of nociceptive sensory neurons and contribute to inflammatory hypersensitivity. Although their function in the periphery is well known, a role for these TRP channels in central pain mechanisms is less well defined. Lipid agonists of TRPV1 are released from peripheral tissues via enzymatic oxidation after burn injury; however, it is not known if burn injury triggers the release of oxidized lipids in the spinal cord. Accordingly, we evaluated whether burn injury evoked the central release of oxidized lipids . Analysis of lipid extracts of spinal cord tissue with HPLC-MS revealed a significant increase in levels of the epoxide and diol metabolites of linoleic acid: 9,10-DiHOME, 12,13-DiHOME, 9(10)-EpOME, and 12(13)-EpOME, that was reduced after intrathecal (i.t.) injection of the oxidative enzyme inhibitor ketoconazole. Moreover, we found that these four lipid metabolites were capable of specifically activating both TRPV1 and TRPA1. Intrathecal injection of specific antagonists to TRPV1 (AMG-517) or TRPA1 (HC-030031) significantly reduced post-burn mechanical and thermal allodynia. Finally, i.t. injection of ketoconazole significantly reversed post-burn mechanical and thermal allodynia. Our data indicate that spinal cord TRPV1 and TRPA1 contributes to pain after burn and identifies a novel class of oxidized lipids elevated in the spinal cord after burn injury. Since the management of burn pain is problematic, these findings point to a novel approach for treating post-burn pain. PMID:27411353

  14. Importance of CRF Receptor-Mediated Mechanisms of the Bed Nucleus of the Stria Terminalis in the Processing of Anxiety and Pain

    PubMed Central

    Tran, Lee; Schulkin, Jay; Greenwood-Van Meerveld, Beverley

    2014-01-01

    Corticotropin-releasing factor (CRF)-mediated mechanisms in the bed nucleus of the stria terminalis (BNST) have a pivotal role in stress-induced anxiety and hyperalgesia. Although CRF is known to activate two receptor subtypes, CRF1 and CRF2, attempts to delineate the specific role of each subtype in modulating anxiety and nociception have been inconsistent. Here we test the hypothesis that CRF1 and CRF2 receptor activation in the anteriolateral BNST (BNSTAL) facilitates divergent mechanisms modulating comorbid anxiety and hyperalgesia. Microinfusions of the specific antagonists CP376395 and Astressin2B into the BNSTAL were used to investigate CRF1 and CRF2 receptor functions, respectively. We found that CRF1 and CRF2 receptors in the BNSTAL had opposing effects on exploratory behavior in the elevated plus-maze, somatic mechanical threshold, and the autonomic and endocrine response to stress. However, CRF1 or CRF2 receptor antagonism in the BNSTAL revealed complementary roles in facilitating the acoustic startle and visceromotor reflexes. Our results suggest that the net effect of CRF1 and CRF2 receptor activation in the BNSTAL is pathway-dependent and provides important insight into the CRF receptor-associated circuitry that likely underpins stress-induced pathologies. PMID:24853772

  15. Rifaximin Alters Intestinal Bacteria and Prevents Stress-Induced Gut Inflammation and Visceral Hyperalgesia in Rats

    PubMed Central

    Xu, Dabo; Gao, Jun; Gillilland, Merritt; Wu, Xiaoyin; Song, Il; Kao, John Y.; Owyang, Chung

    2014-01-01

    Background & Aims Rifaximin is used to treat patients with functional gastrointestinal disorders, but little is known about its therapeutic mechanism. We propose that rifaximin modulates the ileal bacterial community, reduces subclinical inflammation of the intestinal mucosa, and improves gut barrier function to reduce visceral hypersensitivity. Methods We induced visceral hyperalgesia in rats, via chronic water avoidance or repeat restraint stressors, and investigated whether rifaximin altered the gut microbiota, prevented intestinal inflammation, and improved gut barrier function. Quantitative polymerase chain reaction and 454 pyrosequencing were used to analyze bacterial 16S rRNA in ileal contents from the rats. Reverse transcription, immunoblot, and histologic analyses were used to evaluate levels of cytokines, the tight junction protein occludin, and mucosal inflammation, respectively. Intestinal permeability and rectal sensitivity were measured. Results Water avoidance and repeat restraint stress each led to visceral hyperalgesia, accompanied by mucosal inflammation and impaired mucosal barrier function. Oral rifaximin altered the composition of bacterial communities in the ileum (Lactobacillus species became the most abundant) and prevented mucosal inflammation, impairment to intestinal barrier function, and visceral hyperalgesia in response to chronic stress. Neomycin also changed the composition of the ileal bacterial community (Proteobacteria became the most abundant species). Neomycin did not prevent intestinal inflammation or induction of visceral hyperalgesia induced by water avoidance stress. Conclusions Rifaximin alters the bacterial population in the ileum of rats, leading to a relative abundance of Lactobacillus. These changes prevent intestinal abnormalities and visceral hyperalgesia in response to chronic psychological stress. PMID:24161699

  16. The nitroxyl donor, Angeli’s salt, inhibits inflammatory hyperalgesia in rats

    PubMed Central

    Zarpelon, Ana C.; Souza, Guilherme R.; Cunha, Thiago M.; Schivo, Ieda R.S.; Marchesi, Mario; Casagrande, Rubia; Pinge-Filho, Phileno; Cunha, Fernando Q.; Ferreira, Sergio H.; Miranda, Katrina M.; Verri, Waldiceu A.

    2013-01-01

    Nitric oxide modulates pain development. However, there is no evidence on the effect of nitroxyl (HNO/NO−) in nociception. Therefore, we addressed whether nitroxyl inhibits inflammatory hyperalgesia and its mechanism using the nitroxyl donor Angeli’s salt (AS; Na2N2O3). Mechanical hyperalgesia was evaluated using a modified Randall and Selitto method in rats, cytokine production by ELISA and nitroxyl was determined by confocal microscopy in DAF (a cell permeable reagent that is converted into a fluorescent molecule by nitrogen oxides)-treated dorsal root ganglia neurons in culture. Local pre-treatment with AS (17– 450 µg/paw, 30 min) inhibited the carrageenin-induced mechanical hyperalgesia in a dose- and time-dependent manner with maximum inhibition of 97%. AS also inhibited carrageenin-induced cytokine production. AS inhibited the hyperalgesia induced by other inflammatory stimuli including lipopolysaccharide, tumor necrosis factor-α, interleukin-1β and prostaglandin E2. Furthermore, the analgesic effect of AS was prevented by treatment with ODQ (a soluble guanylate cyclase inhibitor), KT5823 (a protein kinase G [PKG] inhibitor) or glybenclamide (an ATP-sensitive K+ channel blocker), but not with naloxone (an opioid receptor antagonist). AS induced concentration-dependent increase in fluorescence intensity of DAF-treated neurons in a L-cysteine (nitroxyl scavenger) sensitive manner. L-cysteine did not affect the NO+ donor S-Nitroso-N-acetyl-DL- penicillamine (SNAP)-induced anti-hyperalgesia or fluorescence of DAF-treated neurons. This is the first study to demonstrate that nitroxyl inhibits inflammatory hyperalgesia by reducing cytokine production and activating the cGMP/PKG/ATP-sensitive K+ channel signaling pathway in vivo. PMID:23541720

  17. Mast Cell-Mediated Mechanisms of Nociception

    PubMed Central

    Aich, Anupam; Afrin, Lawrence B.; Gupta, Kalpna

    2015-01-01

    Mast cells are tissue-resident immune cells that release immuno-modulators, chemo-attractants, vasoactive compounds, neuropeptides and growth factors in response to allergens and pathogens constituting a first line of host defense. The neuroimmune interface of immune cells modulating synaptic responses has been of increasing interest, and mast cells have been proposed as key players in orchestrating inflammation-associated pain pathobiology due to their proximity to both vasculature and nerve fibers. Molecular underpinnings of mast cell-mediated pain can be disease-specific. Understanding such mechanisms is critical for developing disease-specific targeted therapeutics to improve analgesic outcomes. We review molecular mechanisms that may contribute to nociception in a disease-specific manner. PMID:26690128

  18. Mechanisms of PDGF siRNA-mediated inhibition of bone cancer pain in the spinal cord

    PubMed Central

    Xu, Yang; Liu, Jia; He, Mu; Liu, Ran; Belegu, Visar; Dai, Ping; Liu, Wei; Wang, Wei; Xia, Qing-Jie; Shang, Fei-Fei; Luo, Chao-Zhi; Zhou, Xue; Liu, Su; McDonald, JohnW.; Liu, Jin; Zuo, Yun-Xia; Liu, Fei; Wang, Ting-Hua

    2016-01-01

    Patients with tumors that metastasize to bone frequently suffer from debilitating pain, and effective therapies for treating bone cancer are lacking. This study employed a novel strategy in which herpes simplex virus (HSV) carrying a small interfering RNA (siRNA) targeting platelet-derived growth factor (PDGF) was used to alleviate bone cancer pain. HSV carrying PDGF siRNA was established and intrathecally injected into the cavum subarachnoidale of animals suffering from bone cancer pain and animals in the negative group. Sensory function was assessed by measuring thermal and mechanical hyperalgesia. The mechanism by which PDGF regulates pain was also investigated by comparing the differential expression of pPDGFRα/β and phosphorylated ERK and AKT. Thermal and mechanical hyperalgesia developed in the rats with bone cancer pain, and these effects were accompanied by bone destruction in the tibia. Intrathecal injection of PDGF siRNA and morphine reversed thermal and mechanical hyperalgesia in rats with bone cancer pain. In addition, we observed attenuated astrocyte hypertrophy, down-regulated pPDGFRα/β levels, reduced levels of the neurochemical SP, a reduction in CGRP fibers and changes in pERK/ERK and pAKT/AKT ratios. These results demonstrate that PDGF siRNA can effectively treat pain induced by bone cancer by blocking the AKT-ERK signaling pathway. PMID:27282805

  19. Mechanisms of PDGF siRNA-mediated inhibition of bone cancer pain in the spinal cord.

    PubMed

    Xu, Yang; Liu, Jia; He, Mu; Liu, Ran; Belegu, Visar; Dai, Ping; Liu, Wei; Wang, Wei; Xia, Qing-Jie; Shang, Fei-Fei; Luo, Chao-Zhi; Zhou, Xue; Liu, Su; McDonald, JohnW; Liu, Jin; Zuo, Yun-Xia; Liu, Fei; Wang, Ting-Hua

    2016-01-01

    Patients with tumors that metastasize to bone frequently suffer from debilitating pain, and effective therapies for treating bone cancer are lacking. This study employed a novel strategy in which herpes simplex virus (HSV) carrying a small interfering RNA (siRNA) targeting platelet-derived growth factor (PDGF) was used to alleviate bone cancer pain. HSV carrying PDGF siRNA was established and intrathecally injected into the cavum subarachnoidale of animals suffering from bone cancer pain and animals in the negative group. Sensory function was assessed by measuring thermal and mechanical hyperalgesia. The mechanism by which PDGF regulates pain was also investigated by comparing the differential expression of pPDGFRα/β and phosphorylated ERK and AKT. Thermal and mechanical hyperalgesia developed in the rats with bone cancer pain, and these effects were accompanied by bone destruction in the tibia. Intrathecal injection of PDGF siRNA and morphine reversed thermal and mechanical hyperalgesia in rats with bone cancer pain. In addition, we observed attenuated astrocyte hypertrophy, down-regulated pPDGFRα/β levels, reduced levels of the neurochemical SP, a reduction in CGRP fibers and changes in pERK/ERK and pAKT/AKT ratios. These results demonstrate that PDGF siRNA can effectively treat pain induced by bone cancer by blocking the AKT-ERK signaling pathway. PMID:27282805

  20. Two-week cast immobilization induced chronic widespread hyperalgesia in rats.

    PubMed

    Ohmichi, Y; Sato, J; Ohmichi, M; Sakurai, H; Yoshimoto, T; Morimoto, A; Hashimoto, T; Eguchi, K; Nishihara, M; Arai, Y-C P; Ohishi, H; Asamoto, K; Ushida, T; Nakano, T; Kumazawa, T

    2012-03-01

    It has been postulated that physical immobilization is an essential factor in developing chronic pain after trauma or surgery in an extremity. However, the mechanisms of sustained immobilization-induced chronic pain remain poorly understood. The present study, therefore, aimed to develop a rat model for chronic post-cast pain (CPCP) and to clarify the mechanism(s) underlying CPCP. To investigate the effects of cast immobilization on pain behaviours in rats, one hindlimb was immobilized for 2 weeks with a cast and remobilization was conducted for 10 weeks. Cast immobilization induced muscle atrophy and inflammatory changes in the immobilized hindlimb that began 2 h after cast removal and continued for 1 week. Spontaneous pain-related behaviours (licking and reduction in weight bearing) in the immobilized hindlimb were observed for 2 weeks, and widespread mechanical hyperalgesia in bilateral calves, hindpaws and tail all continued for 5-10 weeks after cast removal. A sciatic nerve block with lidocaine 24 h after cast removal transitorily abolished bilateral mechanical hyperalgesia in CPCP rats, suggesting that sensory inputs originating in the immobilized hindlimb contribute to the mechanism of both ipsilateral and contralateral hyperalgesia. Intraperitoneal injection of the free radical scavengers 4-hydroxy-2,2,6,6-tetramethylpiperydine-1-oxy1 or N-acetylcysteine 24 h after cast removal clearly inhibited mechanical hyperalgesia in bilateral calves and hindpaws in CPCP rats. These results suggest that cast immobilization induces ischaemia/reperfusion injury in the hindlimb and consequent production of oxygen free radicals, which may be involved in the mechanism of widespread hyperalgesia in CPCP rats. PMID:22337282

  1. Mechanics of Protein-Mediated DNA Looping

    NASA Astrophysics Data System (ADS)

    Meiners, Jens-Christian

    2009-03-01

    The formation of looped DNA-protein complexes in which a protein or protein assembly binds to multiple distant operator sites on the DNA is a common feature for many regulatory schemes on the transcriptional level. In a living cell, a multitude of mechanical forces and constraints act on these complexes, and it is imperative to understand their effects on biological function. For this aim, we study the lactose repressor as a model system for protein-mediated DNA looping in single-molecule experiments. Using a novel axial constant-force optical trapping scheme that allows us to manipulate sub-micron DNA fragments with well-controlled forces down to the 10 fN range, we show that mechanical tension in the substrate DNA of hundred femtonewton is sufficient to disrupt the loop formation process, which suggests that such mechanical tension may provide a mechanical pathway to controlling gene expression in vivo. From the force sensitivity of the loop formation process, we can also infer the topology of the looped complex; in our case an antiparallel conformation. In addition, we will present new tethered-particle microscopy data that shows lifetimes of the looped complexes that are two to three orders of magnitude shorter than those measured in biochemical competition assays and discuss possible interpretations, including the suggestion that operator binding of the lactose repressor tetramer leads to a destabilization of the dimer-dimer interface and that thus the loop breakdown process is mostly a dissociation of the tetramer into two dimers, instead, as widely assumed, an unbinding of the tetramer from the DNA.

  2. Sex-dependent roles of prolactin and prolactin receptor in postoperative pain and hyperalgesia in mice

    PubMed Central

    Patil, Mayur J.; Green, Dustin P.; Henry, Michael A.; Akopian, Armen N.

    2016-01-01

    Although surgical trauma activates the anterior pituitary gland and elicits an increase in prolactin (PRL) serum levels that can modulate nociceptive responses, the role of PRL and the PRL-receptor (PRL-R) in thermal and mechanical hyperalgesia in postoperative pain is unknown. Acute postoperative pain condition was generated with the use of the hindpaw plantar incision model. Results showed endogenous PRL levels were significantly increased in serum, operated hindpaw and spinal cords of male and female rats 24 hours after incision. These alterations were especially pronounced in females. We then examined the role of the PRL system in thermal and mechanical hyperalgesia in male and female mice 3-168 hours after plantar incision with the use of knock-out (KO) mice with PRL or PRL-R gene ablations and in wild-type (WT) mice. WT mice showed postoperative cold hyperalgesia in a sex-dependent manner (only in females), but with no effect on heat hyperalgesia or mechanical allodynia in either sex. Studies in KO mice showed no effect of PRL and PRL-R gene ablation on heat and cold hyperalgesia in male mice, while heat hyperlgesia were reduced 3-72 hours post-surgery in female PRL and PRL-R KO mice. In contrast, PRL and PRL-R ablations significantly attenuated mechanical allodynia 3-72 hours post-surgery in both male and female mice. Overall, we found elevated PRL levels in serum, hindpaws and spinal cords after incision, and identify a contributory role for the PRL system in postoperative pain responses to thermal stimuli in females and to mechanical stimuli in both males and females. PMID:23994182

  3. Neuroprotective Mechanisms Mediated by CDK5 Inhibition.

    PubMed

    Mushtaq, Gohar; Greig, Nigel H; Anwar, Firoz; Al-Abbasi, Fahad A; Zamzami, Mazin A; Al-Talhi, Hasan A; Kamal, Mohammad A

    2016-01-01

    Cyclin-dependent kinase 5 (CDK5) is a proline-directed serine/threonine kinase belonging to the family of cyclin-dependent kinases. In addition to maintaining the neuronal architecture, CDK5 plays an important role in the regulation of synaptic plasticity, neurotransmitter release, neuron migration and neurite outgrowth. Although various reports have shown links between neurodegeneration and deregulation of cyclin-dependent kinases, the specific role of CDK5 inhibition in causing neuroprotection in cases of neuronal insult or in neurodegenerative diseases is not wellunderstood. This article discusses current evidence for the involvement of CDK5 deregulation in neurodegenerative disorders and neurodegeneration associated with stroke through various mechanisms. These include upregulation of cyclin D1 and overactivation of CDK5 mediated neuronal cell death pathways, aberrant hyperphosphorylation of human tau proteins and/or neurofilament proteins, formation of neurofibrillary lesions, excitotoxicity, cytoskeletal disruption, motor neuron death (due to abnormally high levels of CDK5/p25) and colchicine- induced apoptosis in cerebellar granule neurons. A better understanding of the role of CDK5 inhibition in neuroprotective mechanisms will help scientists and researchers to develop selective, safe and efficacious pharmacological inhibitors of CDK5 for therapeutic use against human neurodegenerative disorders, such as Alzheimer's disease, amyotrophic lateral sclerosis and neuronal loss associated with stroke. PMID:26601962

  4. Neuroprotective Mechanisms Mediated by CDK5 Inhibition

    PubMed Central

    Mushtaq, Gohar; Greig, Nigel H.; Anwar, Firoz; Al-Abbasi, Fahad A.; Zamzami, Mazin A.; Al-Talhi, Hasan A.; Kamal, Mohammad A.

    2016-01-01

    Cyclin-dependent kinase 5 (CDK5) is a proline-directed serine/threonine kinase belonging to the family of cyclin-dependent kinases. In addition to maintaining the neuronal architecture, CDK5 plays an important role in the regulation of synaptic plasticity, neurotransmitter release, neuron migration and neurite outgrowth. Although various reports have shown links between neurodegeneration and deregulation of cyclin-dependent kinases, the specific role of CDK5 inhibition in causing neuroprotection in cases of neuronal insult or in neurodegenerative diseases is not well-understood. This article discusses current evidence for the involvement of CDK5 deregulation in neurodegenerative disorders and neurodegeneration associated with stroke through various mechanisms. These include upregulation of cyclin D1 and overactivation of CDK5 mediated neuronal cell death pathways, aberrant hyperphosphorylation of human tau proteins and/or neurofilament proteins, formation of neurofibrillary lesions, excitotoxicity, cytoskeletal disruption, motor neuron death (due to abnormally high levels of CDK5/p25) and colchicine-induced apoptosis in cerebellar granule neurons. A better understanding of the role of CDK5 inhibition in neuroprotective mechanisms will help scientists and researchers to develop selective, safe and efficacious pharmacological inhibitors of CDK5 for therapeutic use against human neurodegenerative disorders, such as Alzheimer’s disease, amyotrophic lateral sclerosis and neuronal loss associated with stroke. PMID:26601962

  5. ASICs Do Not Play a Role in Maintaining Hyperalgesia Induced by Repeated Intramuscular Acid Injections

    PubMed Central

    Gautam, Mamta; Benson, Christopher J.; Ranier, Jon D.; Light, Alan R.; Sluka, Kathleen A.

    2012-01-01

    Repeated intramuscular acid injections produce long-lasting mechanical hyperalgesia that depends on activation of ASICs. The present study investigated if pH-activated currents in sensory neurons innervating muscle were altered in response to repeated acid injections, and if blockade of ASICs reverses existing hyperalgesia. In muscle sensory neurons, the mean acid-evoked current amplitudes and the biophysical properties of the ASIC-like currents were unchanged following acidic saline injections when compared to neutral pH saline injections or uninjected controls. Moreover, increased mechanical sensitivity of the muscle and paw after the second acid injection was unaffected by local blockade of ASICs (A-317567) in the muscle. As a control, electron microscopic analysis showed that the tibial nerve was undamaged after acid injections. Our previous studies demonstrated that ASICs are important in the development of hyperalgesia to repeated acid injections. However, the current data suggest that ASICs are not involved in maintaining hyperalgesia to repeated intramuscular acid injections. PMID:22191025

  6. Effects of the bisphosphonate ibandronate on hyperalgesia, substance P, and cytokine levels in a rat model of persistent inflammatory pain.

    PubMed

    Bianchi, Mauro; Franchi, Silvia; Ferrario, Paolo; Sotgiu, Maria Luisa; Sacerdote, Paola

    2008-04-01

    The anti-inflammatory and analgesic properties of different bisphosphonates have been demonstrated in both animal and human studies. Ibandronate is a third-generation bisphosphonate effective in managing different types of bone pain. In this study we investigated its effects in a standard pre-clinical model of inflammatory pain. We evaluated the effects of a single injection of different doses (0.5, 1.0, and 2.0 mg/kg i.p.) of ibandronate on inflammatory oedema and cutaneous hyperalgesia produced by the intraplantar injection of complete Freund's adjuvant (CFA) in the rat hind-paw. In addition, we measured the effects of this drug (1.0 mg/kg i.p.) on hind-paw levels of different pro-inflammatory mediators (PGE-2, SP, TNF-alpha, and IL-1beta). We also measured the levels of SP protein and of its mRNA in the ipsilateral dorsal root ganglia (DRG). Ibandronate proved able to reduce the inflammatory oedema, the hyperalgesia to mechanical stimulation, and the levels of SP in the inflamed tissue as measured 3 and 7 days following CFA-injection. This drug significantly reduced the levels of TNF-alpha and IL-1beta only on day 7. On the other hand, the levels of PGE-2 in the inflamed hind-paw were unaffected by the administration of this bisphosphonate. Finally, ibandronate blocked the overexpression of SP mRNA in DRG induced by CFA-injection in the hind-paw. These data help to complete the pharmacodynamic profile of ibandronate, while also suggesting an involvement of several inflammatory mediators, with special reference to substance P, in the analgesic action of this bisphosphonate. PMID:17664076

  7. EVALUATION OF HYPERALGESIA AND HISTOLOGICAL CHANGES OF DORSAL ROOT GANGLION INDUCED BY NUCLEUS PULPOSUS

    PubMed Central

    Grava, André Luiz de Souza; Ferrari, Luiz Fernando; Parada, Carlos Amílcar; Defino, Helton Luiz Aparecido

    2015-01-01

    To evaluate the hyperalgesia and histological abnormalities induced by contact between the dorsal root ganglion and the nucleus pulposus. Methods: Twenty Wistar rats were used, divided into two experimental groups. In one of the groups, a fragment of autologous nucleus pulposus was removed from the sacrococcygeal region and deposited on the L5 dorsal root ganglia. In the other group (control), a fragment of adipose tissue was deposited on the L5 dorsal root ganglia. Mechanical and thermal hyperalgesia was evaluated on the third day and the first, third, fifth and seventh weeks after the operation. A L5 dorsal root ganglion was removed in the first, third, fifth and seventh weeks after the operation for histological study using HE staining and histochemical study using specific labeling for iNOS. Results: Higher intensity of mechanical and thermal hyperalgesia was observed in the group of animals in which the nucleus pulposus was placed in contact with the dorsal root ganglion. In this group, the histological study showed abnormalities of the dorsal root ganglion tissue, characterized by an inflammatory process and axonal degeneration. The histopathological abnormalities of the dorsal root ganglion tissue presented increasing intensity with increasing length of observation, and there was a correlation with maintenance of the hyperalgesia observed in the behavioral assessment. Immunohistochemistry using specific labeling for iNOS in the group of animals in which the nucleus pulposus was placed in contact with the dorsal root ganglion showed higher expression of this enzyme in the nuclei of the inflammatory cells (glial cells) surrounding the neurons. Conclusion: Contact between the nucleus pulposus and the dorsal root ganglion induced mechanical and thermal hyperalgesia and caused histological abnormalities in the dorsal root ganglion components. These abnormalities were characterized by an inflammatory and degenerative process in the structures of the dorsal root

  8. Hyperalgesia in an immobilized rat hindlimb: effect of treadmill exercise using non-immobilized limbs.

    PubMed

    Chuganji, Sayaka; Nakano, Jiro; Sekino, Yuki; Hamaue, Yohei; Sakamoto, Junya; Okita, Minoru

    2015-01-01

    Cast immobilization of limbs causes hyperalgesia, which is a decline of the threshold of mechanical and thermal mechanical stimuli. The immobilization-induced hyperalgesia (IIH) can disturb rehabilitation and activities of daily living in patients with orthopedic disorders. However, it is unclear what therapeutic and preventive approaches can be used to alleviate IIH. Exercise that activates the descending pain modulatory system may be effective for IIH. The purpose of this study was to investigate the effects of treadmill exercise during the immobilization period, using the non-immobilized limbs, on IIH. Thirty-six 8-week-old Wistar rats were randomly divided into (1) control, (2) immobilization (Im), and (3) immobilization and treadmill exercise (Im+Ex) groups. In the Im and Im+Ex groups, the right ankle joints of each rat were immobilized in full plantar flexion with a plaster cast for an 8-week period. In the Im+Ex group, treadmill exercise (15 m/min, 30 min/day, 5 days/week) was administered during the immobilization period while the right hindlimb was kept immobilized. Mechanical hyperalgesia was measured using von Frey filaments every week. To investigate possible activation of the descending pain modulatory system, beta-endorphin expression levels in hypothalamus and midbrain periaqueductal gray were analyzed. Although IIH clearly occurred in the Im group, the hyperalgesia was partially but significantly reduced in the Im+Ex group. Beta-endorphin, which is one of the endogenous opioids, was selectively increased in the hypothalamus and midbrain periaqueductal gray of the Im+Ex group. Our data suggest that treadmill running using the non-immobilized limbs reduces the amount of hyperalgesia induced in the immobilized limb even if it is not freed. This ameliorating effect might be due to the descending pain modulatory system being activated by upregulation of beta-endorphin in the brain. PMID:25304541

  9. A possible correlation between oxytocin-induced and angiotensin IV-induced anti-hyperalgesia at the spinal level in rats.

    PubMed

    Chow, Lok-Hi; Tao, Pao-Luh; Chen, Jin-Chung; Liao, Ruey-Ming; Chang, En-Pei; Huang, Eagle Yi-Kung

    2013-01-01

    In our previous study, we showed that intrathecal (i.t.) administration of angiotensin IV (Ang IV), an insulin-regulated aminopeptidase (IRAP) inhibitor, attenuated inflammatory hyperalgesia in rats. Using the plantar test in rats with carrageenan-induced paw inflammation, we investigated the possible mechanism(s) of this effect. Because i.t. oxytocin was reported to produce a dose-dependent anti-hyperalgesia in rats with inflammation, we speculate that there is a possible correlation between oxytocin-induced and Ang IV-induced anti-hyperalgesia. Using i.t. co-administered atosiban (oxytocin receptor antagonist), the anti-hyperalgesia by Ang IV was completely abolished. This indicated that oxytocin could be the major IRAP substrate responsible for the anti-hyperalgesia by Ang IV. When Ang IV was co-administered with a low dose of oxytocin, there was a significant enhancing effect of Ang IV on oxytocin-induced anti-hyperalgesia. In recent reports, electrical stimulation on the paraventricular hypothalamic nucleus (PVN) was proved to increase oxytocin release at the spinal cord. Our results also showed that Ang IV could prolong the anti-hyperalgesia induced by PVN stimulation. This suggests a possible protective effect of Ang IV on endogenous oxytocin degradation/dysfunctioning. Moreover, we examined the local effect of intraplantarly injected Ang IV in the same model. Our results showed no effect of local Ang IV on hyperalgesia and paw edema, indicating that Ang IV may not regulate the peripheral inflammatory process. Overall, our study suggests that Ang IV may act through the inhibition of the activity of IRAP to reduce the degradation of oxytocin at the spinal cord, thereby leading to anti-hyperalgesia in rats with inflammation. PMID:23142109

  10. Physiological mechanisms mediating aspartame-induced satiety.

    PubMed

    Hall, W L; Millward, D J; Rogers, P J; Morgan, L M

    2003-04-01

    Aspartame has been previously shown to increase satiety. This study aimed to investigate a possible role for the satiety hormones cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1) in this effect. The effects of the constituents of aspartame, phenylalanine and aspartic acid, were also examined. Six subjects consumed an encapsulated preload consisting of either 400 mg aspartame, 176 mg aspartic acid+224 mg phenylalanine, or 400 mg corn flour (control), with 1.5 g paracetamol dissolved in 450 ml water to measure gastric emptying. A 1983-kJ liquid meal was consumed 60 min later. Plasma CCK, GLP-1, glucose-dependent insulinotropic polypeptide (GIP), glucose, and insulin were measured over 0-120 min. Gastric emptying was measured from 0 to 60 min. Plasma GLP-1 concentrations decreased following the liquid meal (60-120 min) after both the aspartame and amino acids preloads (control, 2096.9 pmol/l min; aspartame, 536.6 pmol/l min; amino acids, 861.8 pmol/l min; incremental area under the curve [AUC] 60-120 min, P<.05). Desire to eat was reduced from 60 to 120 min following the amino acids preload (control, -337.1 mm min; aspartame, -505.4 mm min; amino acids, -1497.1 mm min; incremental AUC 60-120 min, P<.05). However, gastric emptying rates, plasma CCK, GIP, insulin, and glucose concentrations were unaffected. There was a correlation between the increase in plasma phenylalanine and decrease in desire to eat after the liquid meal following the constituent amino acids (r=-.9774, P=.004). In conclusion, it is unlikely that aspartame increases satiety via CCK- or GLP-1-mediated mechanisms, but small changes in circulating phenylalanine concentrations may influence appetite. PMID:12782208

  11. Intradermal injection of Botulinum toxin type A alleviates infraorbital nerve constriction-induced thermal hyperalgesia in an operant assay.

    PubMed

    Kumada, A; Matsuka, Y; Spigelman, I; Maruhama, K; Yamamoto, Y; Neubert, J K; Nolan, T A; Watanabe, K; Maekawa, K; Kamioka, H; Yamashiro, T; Kuboki, T; Oguma, K

    2012-01-01

    Recent studies have shown that infraorbital nerve constriction (IoNC)-induced mechanical allodynia has been attenuated by administration of highly purified 150-kDa Botulinum neurotoxin type A (BoNT/A). Here, we extend these studies to determine whether BoNT/A could attenuate IoNC-induced symptoms of thermal hyperalgesia. Instead of testing head withdrawal thresholds, a thermal operant assay was used to evaluate cortical processing of sensory input following IoNC. In this assay, a fasted rat's desire to obtain a food reward (sweetened condensed milk) is coupled to its ability to tolerate facial contact with a warm (45 °C) thermode. Bilateral IoNC decreased the ratio of thermode contact duration/event, which is an indicative of thermal hyperalgesia. BoNT/A injection intradermally in the area of infraorbital nerve (IoN) innervation 7 days after IoNC resulted in decreased number of facial contacts and increased the ratio of contact duration/event (measured at 14 days after IoNC). The BoNT/A (2-200 pg) effects were dose dependent and statistically significant at 100 and 200 pg (P < 0·05). Complete reversal of thermal hyperalgesia symptoms was obtained with a 200-pg dose, without affecting sham rat behaviour. Off-site (neck) injection of BoNT/A did not relieve thermal hyperalgesia, while co-injection of BoNT/A with a neutralising antibody in the area of IoN innervation prevented relief of thermal hyperalgesia. Neither IoNC nor BoNT/A injection affected operant assay parameters with a 24 °C thermode, indicating selectivity of thermal hyperalgesia measurements. These results strongly suggest that intradermal injection of BoNT/A in the area of IoN innervation alleviates IoNC-induced thermal hyperalgesia in an operant assay. PMID:21793870

  12. Intrathecal rapamycin attenuates morphine-induced analgesic tolerance and hyperalgesia in rats with neuropathic pain

    PubMed Central

    Xu, Ji-Tian; Sun, Linlin; Lutz, Brianna Marie; Bekker, Alex; Tao, Yuan-Xiang

    2015-01-01

    Repeated and long-term administration of opioids is often accompanied by the initiation of opioid-induced analgesic tolerance and hyperalgesia in chronic pain patients. Our previous studies showed that repeated intrathecal morphine injection activated the mammalian target of rapamycin complex 1 (mTORC1) in spinal dorsal horn neurons and that blocking this activation prevented the initiation of morphine-induced tolerance and hyperalgesia in healthy rats. However, whether spinal mTORC1 is required for morphine-induced tolerance and hyperalgesia under neuropathic pain conditions remains elusive. We here observed the effect of intrathecal infusion of rapamycin, a specific mTORC1 inhibitor, on morphine-induced tolerance and hyperalgesia in a neuropathic pain model in rats induced by the fifth lumbar spinal nerve ligation (SNL). Continuous intrathecal infusion of morphine for one week starting on day 8 post-SNL led to morphine tolerance demonstrated by morphine-induced reduction in maximal possible analgesic effect (MPAE) to tail heat stimuli and ipsilateral paw withdrawal threshold (PWT) to mechanical stimuli in SNL rats. Such reduction was attenuated by co-infusion of rapamycin. Co-infusion of rapamycin also blocked morphine tolerance demonstrated by attenuation of morphine-induced reduction in MPAE in sham rats and morphine-induced hyperalgesia demonstrated by the reverse of morphine-induced reduction in PWT on both sides of sham rats and on the contralateral side of SNL rats. The results suggest that mTORC1 inhibitors could serve as promising medications for use as adjuvants with opioids in clinical neuropathic pain management. PMID:26339682

  13. Heat stroke: opioid-mediated mechanisms.

    PubMed

    Romanovsky, A A; Blatteis, C M

    1996-12-01

    In our previous study in guinea pigs, intensive and prolonged intraperitoneal heating (IPH) caused heat stroke characterized by high mortality and accompanied by two paradoxical phenomena: ear skin vasoconstriction at a high body temperature (Tb) (hyperthermia-induced vasoconstriction) and a post-IPH Tb fall at an ambient temperature (Ta) below thermoneutrality (hyperthermia-induced hypothermia). In this study, we tested the hypothesis that the mechanisms of the two phenomena involve endogenous opioid agonists. Experiments were conducted in 24 unanesthetized, lightly restrained guinea pigs, each chronically implanted with an intraperitoneal thermode and intrahypothalamic thermocouple. The thermoregulatory effects of a wide-spectrum opioid-receptor antagonist, naltrexone (NTX; 50 or 0 mumol/kg sc), were studied in IPH-induced heat stroke and under normal conditions. IPH was accomplished by perfusing (50 ml/min; 80 min) water (45 degrees C) through the thermode. Ta was maintained at approximately 24 degrees C. Skin vasodilation occurred at the onset of IPH but later changed to vasoconstriction despite high Tb and continuing IPH. IPH-induced hyperthermia (1.8 +/- 0.1 degrees C) was followed by a post-IPH Tb fall (-5.1 +/- 0.7 degree C; calculated for the survivors only). The 48-h mortality rate was 50%. NTX prevented the hyperthermia-induced vasoconstriction and attenuated the hyperthermia-induced hypothermia (-1.8 +/- 0.4 degree C). None of the NTX-treated animals died. The effects of NTX on Tb regulation under normal conditions were minor. These results indicate that the phenomena of both hyperthermia-induced vasoconstriction and hyperthermia-induced hypothermia are opioid dependent. The latter is speculated to reflect opioid-mediated inhibition of metabolism; the former is thought to result from opioid-induced hemodynamic alterations. Because both phenomena did not occur in the NTX-treated survivors, the skin vasoconstriction at high Tb and the posthyperthermia Tb

  14. Opioid-induced hyperalgesia and burn pain.

    PubMed

    Holtman, Joseph R; Jellish, W Scott

    2012-01-01

    The treatment of pain produced during the management of burn injury has been an ongoing problem for physicians caring for these patients. The main therapeutic option for analgesia has been the repeated and prolonged use of opioids. The adverse effects of opioids are well known but the long term use of opioids which produces tolerance with accompanying dose escalation and dependence is most problematic. Another potentially important consequence of opioid exposure that sometimes masks as tolerance is that of opioid induced hyperalgesia. This syndrome is manifest as enhanced pain, sensitivity and loss of analgesic efficacy in patients treated with opioids who actually become sensitized to painful stimuli. This article focuses on the treatment of burn pain and how current analgesic therapies with opioids may cause hyperalgesia and affect the adequacy of treatment for burn pain. This article also provides possible modalities to help therapeutically manage these patients and considers future analgesic strategies which may help to improve pain management in this complicated patient population. PMID:23143613

  15. Transient Heat Hyperalgesia During Resolution of Ropivacaine Sciatic Nerve Block in the Rat

    PubMed Central

    Kolarczyk, Lavinia M.; Williams, Brian A.

    2011-01-01

    Background Preliminary studies using perineural sciatic ropivacaine in rat demonstrated unexpected heat hyperalgesia after block resolution. To better characterize the time course relative to mechanical anesthesia-analgesia, we tested the hypothesis that ropivacaine 0.5% leads to transient heat hyperalgesia in rat independent of mechanical nociception. We also evaluated functional toxicity (e.g., long-term hyperalgesia and/or tactile allodynia 2 weeks post-injection). Methods Under surgical exposure, left sciatic nerve block was performed in 2 groups of adult male rats – ropivacaine (200 μL, 5 mg/mL, n=14) versus vehicle (n=11). The efficacy and duration of block was assessed with serial heat, mechanical (Randall-Selitto testing), and tactile (von Frey-like monofilaments) tests; motor-proprioceptive (rotarod) and sedation tests were employed 1 hr and 7 hr post-injection. The presence of nerve injury was assessed by repeating the heat, tactile, and motor tests 12–14 days post-injection. Results Ropivacaine-induced anesthesia was fully manifest at 1 hr post-injection. At 3 hr post-injection, heat hypersensitivity was present in the setting of resolved mechanical analgesia. All behavioral measures returned to baseline by 2 wk post-injection. There was no evidence of (i) behavioral sedation, (ii) persistent changes in heat or mechanical sensitivity, or (iii) persistent changes in proprioceptive-motor function at 12–14 days post-injection. Conclusions Ropivacaine 0.5% induces transient heat hyperalgesia in the setting of resolved mechanical analgesia, further suggestive of modality and/or nociceptive fiber specificity. Whether this finding partially translates to “rebound pain” after patients’ nerve blocks wear off requires further study. PMID:21451438

  16. Homocysteine-induced attenuation of vascular endothelium-dependent hyperalgesia in the rat.

    PubMed

    Joseph, E K; Green, P G; Ferrari, L F; Levine, J D

    2015-01-22

    We have recently demonstrated a role of the vascular endothelium in peripheral pain mechanism by disrupting endothelial cell function using intravascular administration of octoxynol-9, a non-selective membrane active agent. As an independent test of the role of endothelial cells in pain mechanisms, we evaluated the effect of homocysteine, an agent that damages endothelial cell function. Mechanical stimulus-induced enhancement of endothelin-1 hyperalgesia in the gastrocnemius muscle of the rat was first prevented then enhanced by intravenous administration of homocysteine, but was only inhibited by its precursor, methionine. Both homocysteine and methionine significantly attenuated mechanical hyperalgesia in two models of ergonomic muscle pain, induced by exposure to vibration, and by eccentric exercise, and cutaneous mechanical hyperalgesia in an ischemia-reperfusion injury model of Complex Regional Pain Syndrome type I, all previously shown responsive to octoxynol-9. This study provides independent support for a role of the endothelial cell in pain syndromes thought to have a vascular basis, and suggests that substances that are endothelial cell toxins can enhance vascular pain. PMID:25451284

  17. Chronic CRF1 receptor blockade reduces heroin intake escalation and dependence-induced hyperalgesia.

    PubMed

    Park, Paula E; Schlosburg, Joel E; Vendruscolo, Leandro F; Schulteis, Gery; Edwards, Scott; Koob, George F

    2015-03-01

    Opioids represent effective drugs for the relief of pain, yet chronic opioid use often leads to a state of increased sensitivity to pain that is exacerbated during withdrawal. A sensitization of pain-related negative affect has been hypothesized to closely interact with addiction mechanisms. Neuro-adaptive changes occur as a consequence of excessive opioid exposure, including a recruitment of corticotropin-releasing factor (CRF) and norepinephrine (NE) brain stress systems. To better understand the mechanisms underlying the transition to dependence, we determined the effects of functional antagonism within these two systems on hyperalgesia-like behavior during heroin withdrawal utilizing models of both acute and chronic dependence. We found that passive or self-administered heroin produced a significant mechanical hypersensitivity. During acute opioid dependence, systemic administration of the CRF1 receptor antagonist MPZP (20 mg/kg) alleviated withdrawal-induced mechanical hypersensitivity. In contrast, several functional adrenergic system antagonists (clonidine, prazosin, propranolol) failed to alter mechanical hypersensitivity in this state. We then determined the effects of chronic MPZP or clonidine treatment on extended access heroin self-administration and found that MPZP, but not clonidine, attenuated escalation of heroin intake, whereas both drugs alleviated chronic dependence-associated hyperalgesia. These findings suggest that an early potentiation of CRF signaling occurs following opioid exposure that begins to drive both opioid-induced hyperalgesia and eventually intake escalation. PMID:24330252

  18. PLGA-Curcumin Attenuates Opioid-Induced Hyperalgesia and Inhibits Spinal CaMKIIα

    PubMed Central

    Hu, Xiaoyu; Huang, Fang; Szymusiak, Magdalena; Tian, Xuebi; Liu, Ying; Wang, Zaijie Jim

    2016-01-01

    Opioid-induced hyperalgesia (OIH) is one of the major problems associated with prolonged use of opioids for the treatment of chronic pain. Effective treatment for OIH is lacking. In this study, we examined the efficacy and preliminary mechanism of curcumin in attenuating OIH. We employed a newly developed PLGA-curcumin nanoformulation (PLGA-curcumin) in order to improve the solubility of curcumin, which has been a major obstacle in properly characterizing curcumin’s mechanism of action and efficacy. We found that curcumin administered intrathecally or orally significantly attenuated hyperalgesia in mice with morphine-induced OIH. Furthermore, we demonstrated that the effects of curcumin on OIH correlated with the suppression of chronic morphine-induced CaMKIIα activation in the superficial laminae of the spinal dorsal horn. These data suggest that PLGA-curcumin may reverse OIH possibly by inhibiting CaMKIIα and its downstream signaling. PMID:26744842

  19. PLGA-Curcumin Attenuates Opioid-Induced Hyperalgesia and Inhibits Spinal CaMKIIα.

    PubMed

    Hu, Xiaoyu; Huang, Fang; Szymusiak, Magdalena; Tian, Xuebi; Liu, Ying; Wang, Zaijie Jim

    2016-01-01

    Opioid-induced hyperalgesia (OIH) is one of the major problems associated with prolonged use of opioids for the treatment of chronic pain. Effective treatment for OIH is lacking. In this study, we examined the efficacy and preliminary mechanism of curcumin in attenuating OIH. We employed a newly developed PLGA-curcumin nanoformulation (PLGA-curcumin) in order to improve the solubility of curcumin, which has been a major obstacle in properly characterizing curcumin's mechanism of action and efficacy. We found that curcumin administered intrathecally or orally significantly attenuated hyperalgesia in mice with morphine-induced OIH. Furthermore, we demonstrated that the effects of curcumin on OIH correlated with the suppression of chronic morphine-induced CaMKIIα activation in the superficial laminae of the spinal dorsal horn. These data suggest that PLGA-curcumin may reverse OIH possibly by inhibiting CaMKIIα and its downstream signaling. PMID:26744842

  20. Chronic intermittent voluntary alcohol drinking induces hyperalgesia in Sprague-Dawley rats

    PubMed Central

    Fu, Rao; Gregor, Danielle; Peng, Zengliu; Li, Jing; Bekker, Alex; Ye, Jianghong

    2015-01-01

    The mechanisms of hyperalgesia in alcoholics are not completely clear, and the development of animal models would therefore be necessary in investigating the underlying changes. Several studies including our own have demonstrated that the intermittent access to 20% ethanol two-bottle choice procedure (IA2BC) promotes escalation of drinking, and induces physical dependence in the Sprague-Dawley (SD) rat, one of the strains most commonly used in preclinical alcohol research. In this study, we investigated whether the IA2BC procedure could produce hyperalgesia in SD rats. We show here that, the SD rats in the IA2BC procedure significantly escalated their drinking within 8 weeks, which is consistent with other studies. Starting from 8 weeks of repeated chronic drinking, the mechanical and thermal sensitivity was significantly increased. During withdrawal, there were noticeable physical dependence signs, including tail stiffness and lower limb flexion, which started at 4 hours and lasted for more than 3 days after ethanol removal. Importantly, during withdrawal, the mechanical and thermal sensitivity was further increased, which started at 12 hours and lasted for more than seven days after ethanol removal. These results suggest that utilizing the SD rat under the IA2BC procedure could be a useful animal model with heuristic value for exploring the mechanisms underlying hyperalgesia induced by chronic alcohol abuse. PMID:26823962

  1. Movement-evoked hyperalgesia induced by lipopolysaccharides is not suppressed by glucocorticoids

    PubMed Central

    Kovács, Katalin J.; Papic, Jonathan C.; Larson, Alice A.

    2008-01-01

    Systemic exposure to lipopolysaccharides (LPS) produces a variety of effects, including movement-evoked hyperalgesia that can be measured using the grip force assay in mice. Because both lethality and enhanced sensitivity to cutaneous pain following exposure to endotoxins have each been attributed to inflammatory mediators, we explored the possibility that LPS-induced movement-evoked hyperalgesia is also sensitive to manipulations of glucocorticoids that regulate these other LPS responses. We found that the hyperalgesic effect of LPS (5 mg/kg s.c.) in mice that were adrenalectomized did not differ from that in control mice that were sham-operated, even though mortality after LPS was potentiated by adrenalectomy. The development of tolerance to the movement-evoked hyperalgesic effect of LPS also did not differ between adrenalectomized and sham-operated control mice. In addition, mifepristone (25 mg/kg s.c.), a glucocorticoid antagonist, did not attenuate the hyperalgesic effect of LPS (2 mg/kg s.c.), yet this dose of mifepristone was sufficient to enhance the incidence of lethality induced by LPS. Enhancement of glucocorticoid activity by two injections of dexamethasone (1 mg/kg s.c.) had no effect on the degree of hyperalgesia in mice injected with LPS (5 mg/kg s.c.), yet this dose of dexamethasone was sufficient to attenuate the incidence of mortality induced by LPS in adrenalectomized mice. Finally, morphine (10 mg/kg i.p.) reversed the decrease in grip force caused by LPS (5 mg/kg i.p.), supporting the interpretation that decreases in grip force produced by LPS reflect muscle hyperalgesia that is not sensitive to glucocorticoids. PMID:17686584

  2. Influence of trimebutine on inflammation- and stress-induced hyperalgesia to rectal distension in rats.

    PubMed

    Lacheze, C; Coelho, A M; Fioramonti, J; Buéno, L

    1998-08-01

    The effects of trimebutine and its major metabolite, N-desmethyltrimebutine on inflammation- and stress-induced rectal hyperalgesia have been evaluated in rats fitted with electrodes implanted in the longitudinal striated muscle of the abdomen. Intermittent rectal distension was performed before and 3 days after induction of rectal inflammation by local infusion of trinitrobenzenesulphonic acid (in ethanol). Stress consisted of 2h partial restraint and rectal distension was performed before and 30min after the end of the partial restraint session. The animals were treated intraperitoneally with trimebutine or desmethyltrimebutine (5, 10 or 20mgkg(-1)) or vehicle 15min before rectal distension. Naloxone (1mgkg(-1)) or saline was injected subcutaneously before trimebutine and desmethyltrimebutine. Before treatment trimebutine at the highest dose (20mgkg(-1)) reduced the abdominal response to rectal distension for the highest volume of distension (1.6mL) whereas desmethyltrimebutine was inactive. After rectocolitis the abdominal response to rectal distension was enhanced and trimebutine at 5mgkg(-1) reduced and at 10 mgkg(-1) suppressed inflammation-induced hyperalgesia, an effect reversed by naloxone. Desmethyltrimebutine was inactive. Stress-induced hypersensitivity was attenuated or suppressed, or both, by trimebutine and desmethyltrimebutine at doses of 5, 10 or 20mgkg(-l); greater efficacy was observed for desmethyltrimebutine and the effects were not reversed by naloxone. It was concluded that trimebutine and desmethyltrimebutine are active against inflammation- and stress-induced rectal hyperalgesia but act differently. The effect of trimebutine on inflammation-induced hyperalgesia is mediated through opioid receptors. PMID:9751458

  3. Oral administration of stavudine induces hyperalgesia without affecting activity in rats.

    PubMed

    Weber, Juliane; Mitchell, Duncan; Kamerman, Peter R

    2007-12-01

    We have investigated whether long-term oral administration of the nucleoside reverse transcriptase inhibitor (NRTI) stavudine affects nociception in Sprague-Dawley rats, and whether any changes of nociception are accompanied by deterioration in activity and appetite. Stavudine (50 mg kg(-1)) was administered to rats orally once daily for six weeks in gelatine cubes. Mechanical hyperalgesia of the tail was assessed using a bar algometer, and thermal hyperalgesia by tail immersion in 49 degrees C water. Withdrawal latencies were compared to those of rats receiving placebo gelatine cubes. Withdrawal latencies to the noxious thermal challenge were not affected by stavudine, but those to the mechanical challenge were significantly decreased in rats receiving stavudine, compared to rats receiving placebo, from week three to week six of drug administration (P<0.05, ANCOVA with Newman Keuls post-hoc comparisons). The overall condition of the rats was assessed by recording daily voluntary wheel running distance and maximum running speed, food intake and body mass. Daily stavudine administration did not adversely affect voluntary running activity, appetite or growth. We have shown that long-term daily oral administration of the NRTI stavudine results in mechanical hyperalgesia in rats within three weeks without affecting appetite, growth and physical activity. PMID:17632188

  4. Molecular pathways mediating mechanical signaling in bone

    PubMed Central

    Rubin, Janet; Rubin, Clinton; Jacobs, Christopher Rae

    2013-01-01

    Bone tissue has the capacity to adapt to its functional environment such that its morphology is “optimized” for the mechanical demand. The adaptive nature of the skeleton poses an interesting set of biological questions (e.g., how does bone sense mechanical signals, what cells are the sensing system, what are the mechanical signals that drive the system, what receptors are responsible for transducing the mechanical signal, what are the molecular responses to the mechanical stimuli). Studies of the characteristics of the mechanical environment at the cellular level, the forces that bone cells recognize, and the integrated cellular responses are providing new information at an accelerating speed. This review first considers the mechanical factors that are generated by loading in the skeleton, including strain, stress and pressure. Mechanosensitive cells placed to recognize these forces in the skeleton, osteoblasts, osteoclasts, osteocytes and cells of the vasculature are reviewed. The identity of the mechanoreceptor(s) is approached, with consideration of ion channels, integrins, connexins, the lipid membrane including caveolar and noncaveolar lipid rafts and the possibility that altering cell shape at the membrane or cytoskeleton alters integral signaling protein associations. The distal intracellular signaling systems on-line after the mechanoreceptor is activated are reviewed, including those emanating from G-proteins (e.g., intracellular calcium shifts), MAPKs, and nitric oxide. The ability to harness mechanical signals to improve bone health through devices and exercise is broached. Increased appreciation of the importance of the mechanical environment in regulating and determining the structural efficacy of the skeleton makes this an exciting time for further exploration of this area. PMID:16361069

  5. Opioid-induced hyperalgesia in chronic pain patients and the mitigating effects of gabapentin

    PubMed Central

    Stoicea, Nicoleta; Russell, Daric; Weidner, Greg; Durda, Michael; Joseph, Nicholas C.; Yu, Jeffrey; Bergese, Sergio D.

    2015-01-01

    Chronic pain patients receiving opioid drugs are at risk for opioid-induced hyperalgesia (OIH), wherein opioid pain medication leads to a paradoxical pain state. OIH involves central sensitization of primary and secondary afferent neurons in the dorsal horn and dorsal root ganglion, similar to neuropathic pain. Gabapentin, a gamma-aminobutyric acid (GABA) analog anticonvulsant used to treat neuropathic pain, has been shown in animal models to reduce fentanyl hyperalgesia without compromising analgesic effect. Chronic pain patients have also exhibited lower opioid consumption and improved pain response when given gabapentin. However, few human studies investigating gabapentin use in OIH have been performed in recent years. In this review, we discuss the potential mechanisms that underlie OIH and provide a critical overview of interventional therapeutic strategies, especially the clinically-successful drug gabapentin, which may reduce OIH. PMID:26074817

  6. I - Prostaglandin hyperalgesia, a cAMP/Ca2+ dependent process.

    PubMed

    Ferreira, S H; Nakamura, M

    1979-08-01

    Prostaglandins stimulate cAMP increase in several biological systems including CNS. The possible participation of a cAMP/Ca2+ related mechanism in prostaglandin induced hyperalgesia in the rat paw, as measured by a modification of the Randall-Selitto method was investigated. A serie of agents was administered in the paw in an attempt to change either Ca2+ or cyclic AMP concentration at the nociceptive terminations. PGE2, dibutyryl cyclic AMP, isoprenaline, noradrenaline, adrenaline, Ca2+ionophore (A23187), BaCl2 caused a dose dependent hyperalgesia. The hyperalgesic effect of these substances was enhanced by methyl-xanthines. Cyclic GMP as well as agents which interfere with Ca2+ influx (verapamil and lanthanum) were local analgesics in normal and hyperalgesic paws. PMID:230542

  7. Subjects with Knee Osteoarthritis Exhibit Widespread Hyperalgesia to Pressure and Cold.

    PubMed

    Moss, Penny; Knight, Emma; Wright, Anthony

    2016-01-01

    Hyperalgesia to mechanical and thermal stimuli are characteristics of a range of disorders such as tennis elbow, whiplash and fibromyalgia. This study evaluated the presence of local and widespread mechanical and thermal hyperalgesia in individuals with knee osteoarthritis, compared to healthy control subjects. Twenty-three subjects with knee osteoarthritis and 23 healthy controls, matched for age, gender and body mass index, were recruited for the study. Volunteers with any additional chronic pain conditions were excluded. Pain thresholds to pressure, cold and heat were tested at the knee, ipsilateral heel and ipsilateral elbow, in randomized order, using standardised methodology. Significant between-groups differences for pressure pain and cold pain thresholds were found with osteoarthritic subjects demonstrating significantly increased sensitivity to both pressure (p = .018) and cold (p = .003) stimuli, compared with controls. A similar pattern of results extended to the pain-free ipsilateral ankle and elbow indicating widespread pressure and cold hyperalgesia. No significant differences were found between groups for heat pain threshold, although correlations showed that subjects with greater sensitivity to pressure pain were also likely to be more sensitive to both cold pain and heat pain. This study found widespread elevated pain thresholds in subjects with painful knee osteoarthritis, suggesting that altered nociceptive system processing may play a role in ongoing arthritic pain for some patients. PMID:26809009

  8. Subjects with Knee Osteoarthritis Exhibit Widespread Hyperalgesia to Pressure and Cold

    PubMed Central

    Moss, Penny; Knight, Emma; Wright, Anthony

    2016-01-01

    Hyperalgesia to mechanical and thermal stimuli are characteristics of a range of disorders such as tennis elbow, whiplash and fibromyalgia. This study evaluated the presence of local and widespread mechanical and thermal hyperalgesia in individuals with knee osteoarthritis, compared to healthy control subjects. Twenty-three subjects with knee osteoarthritis and 23 healthy controls, matched for age, gender and body mass index, were recruited for the study. Volunteers with any additional chronic pain conditions were excluded. Pain thresholds to pressure, cold and heat were tested at the knee, ipsilateral heel and ipsilateral elbow, in randomized order, using standardised methodology. Significant between-groups differences for pressure pain and cold pain thresholds were found with osteoarthritic subjects demonstrating significantly increased sensitivity to both pressure (p = .018) and cold (p = .003) stimuli, compared with controls. A similar pattern of results extended to the pain-free ipsilateral ankle and elbow indicating widespread pressure and cold hyperalgesia. No significant differences were found between groups for heat pain threshold, although correlations showed that subjects with greater sensitivity to pressure pain were also likely to be more sensitive to both cold pain and heat pain. This study found widespread elevated pain thresholds in subjects with painful knee osteoarthritis, suggesting that altered nociceptive system processing may play a role in ongoing arthritic pain for some patients. PMID:26809009

  9. Structural mechanisms of chaperone mediated protein disaggregation

    PubMed Central

    Sousa, Rui

    2014-01-01

    The ClpB/Hsp104 and Hsp70 classes of molecular chaperones use ATP hydrolysis to dissociate protein aggregates and complexes, and to move proteins through membranes. ClpB/Hsp104 are members of the AAA+ family of proteins which form ring-shaped hexamers. Loops lining the pore in the ring engage substrate proteins as extended polypeptides. Interdomain rotations and conformational changes in these loops coupled to ATP hydrolysis unfold and pull proteins through the pore. This provides a mechanism that progressively disrupts local secondary and tertiary structure in substrates, allowing these chaperones to dissociate stable aggregates such as β-sheet rich prions or coiled coil SNARE complexes. While the ClpB/Hsp104 mechanism appears to embody a true power-stroke in which an ATP powered conformational change in one protein is directly coupled to movement or structural change in another, the mechanism of force generation by Hsp70s is distinct and less well understood. Both active power-stroke and purely passive mechanisms in which Hsp70 captures spontaneous fluctuations in a substrate have been proposed, while a third proposed mechanism—entropic pulling—may be able to generate forces larger than seen in ATP-driven molecular motors without the conformational coupling required for a power-stroke. The disaggregase activity of these chaperones is required for thermotolerance, but unrestrained protein complex/aggregate dissociation is potentially detrimental. Disaggregating chaperones are strongly auto-repressed, and are regulated by co-chaperones which recruit them to protein substrates and activate the disaggregases via mechanisms involving either sequential transfer of substrate from one chaperone to another and/or simultaneous interaction of substrate with multiple chaperones. By effectively subjecting substrates to multiple levels of selection by multiple chaperones, this may insure that these potent disaggregases are only activated in the appropriate context. PMID

  10. Thermally mediated mechanism to enhance magnetoelectric coupling in multiferroics.

    PubMed

    Chang, C-M; Mani, B K; Lisenkov, S; Ponomareva, I

    2015-05-01

    The main roadblock on the way to practical realization of magnetoelectric devices is the lack of multiferroics with strong magnetoelectric coupling. We propose an unusual route to dramatically enhance this coupling through a thermally mediated mechanism. Such a thermally mediated magnetoelectric effect is quantified by an isentropic rather than isothermal magnetoelectric response and is computed here from first principles. A robust enhancement of the magnetoelectric coupling is predicted for both naturally occurring and heterostructured materials. PMID:25978260

  11. Mechanisms of cytoskeleton-mediated mechanical signal transmission in cells

    PubMed Central

    Hwang, Yongyun; Gouget, Cecile L.M.; Barakat, Abdul I.

    2012-01-01

    Recent experiments have demonstrated very rapid long-distance transmission of mechanical forces within cells. Because the speed of this transmission greatly exceeds that of reaction-diffusion signaling, it has been conjectured that it occurs via the propagation of elastic waves through the actin stress fiber network. To explore the plausibility of this conjecture, we recently developed a model of small amplitude stress fiber deformations in prestressed viscoelastic stress fibers subjected to external forces. The model results demonstrated that rapid mechanical signal transmission is only possible when the external force is applied orthogonal to the stress fiber axis and that the dynamics of this transmission are governed by a balance between the prestress in the stress fiber and the stress fiber's material viscosity. The present study, which is a follow-up on our previous model, uses dimensional analysis to: (1) further evaluate the plausibility of the elastic wave conjecture and (2) obtain insight into mechanical signal transmission dynamics in simple stress fiber networks. We show that the elastic wave scenario is likely not the mechanism of rapid mechanical signal transmission in actin stress fibers due to the highly viscoelastic character of these fibers. Our analysis also demonstrates that the time constant characterizing mechanical stimulus transmission is strongly dependent on the topology of the stress fiber network, implying that network organization plays an important role in determining the dynamics of cellular responsiveness to mechanical stimulation. PMID:23336020

  12. Monocular and binocular mechanisms mediating flicker adaptation.

    PubMed

    Zhuang, Xiaohua; Shevell, Steven K

    2015-12-01

    Flicker adaptation reduces subsequent temporal contrast sensitivity. Recent studies show that this adaptation likely results from neural changes in the magnocellular visual pathway, but whether this adaptation occurs at a monocular or a binocular level, or both, is unclear. Here, two experiments address this question. The first experiment exploits the observation that flicker adaptation is stronger at higher than lower temporal frequencies. Observers' two eyes adapted to 3Hz flicker with an incremental pulse at 1/4 duty cycle, either in-phase or out-of-phase in the two eyes. At the binocular level, the flicker rate was 6Hz in the out-of-phase condition if the two eyes' pulse trains sum. Similar sensitivity reduction was found in both phase conditions, as expected for independent monocular adapting mechanisms. The second experiment tested for interocular transfer of adaptation between eyes. Results showed that (1) flicker adaptation was strongest with adapting and test fields in only the same eye, (2) adaptation can be partially transferred interocularly with adaptation in only the opposite eye, and (3) adaptation was weakened when both eyes were adapted simultaneously at different contrasts, compared to test-eye adaptation alone. Taken together, the findings are consistent with mechanisms of flicker adaptation at both the monocular and binocular level. PMID:26505684

  13. Atenolol Reduces Leishmania major-Induced Hyperalgesia and TNF-α Without Affecting IL-1β or Keratinocyte Derived Chemokines (KC).

    PubMed

    Karam, Marc C; Merckbawi, Rana; Salman, Sara; Mobasheri, Ali

    2016-01-01

    Infection with a high dose of the intracellular parasitic protozoan Leishmania major induces a sustained hyperalgesia in susceptible BALB/c mice accompanied by up-regulation of the pro-inflammatory cytokines IL-1β and IL-6. Interleukin-13 (IL-13) has been shown to reduce this hyperalgesia (despite increased levels of IL-6) and the levels of IL-1β during and after the treatment period. These findings favor the cytokine cascade leading to the production of sympathetic amines (involving TNF-α and KC) over prostaglandins (involving IL-lβ and IL-6) as the final mediators of hyperalgesia. The aim of this study was to investigate the effect of daily treatment with the β-blockers atenolol on L. major-induced inflammation in mice with respect to hyperalgesia as well as the levels of TNF-α and KC (the analog of IL-8 in mice). Our data demonstrates that atenolol is able to reduce the L. major induced sustained peripheral hyperalgesia, which does not seem to involve a direct role for neither IL-lβ nor KC. Moreover, our results show that TNF-α may play a pivotal and direct role in sensitizing the peripheral nerve endings (nociceptors) since its level was reduced during the period of atenolol treatment, which correlates well with the reduction of the observed peripheral, but not central, hyperalgesia. These findings contribute to a better understanding of the cytokine cascade leading to hyperalgesia and may lead to the development of new and more efficient medications for many types of pain. PMID:26913003

  14. Atenolol Reduces Leishmania major-Induced Hyperalgesia and TNF-α Without Affecting IL-1β or Keratinocyte Derived Chemokines (KC)

    PubMed Central

    Karam, Marc C.; Merckbawi, Rana; Salman, Sara; Mobasheri, Ali

    2016-01-01

    Infection with a high dose of the intracellular parasitic protozoan Leishmania major induces a sustained hyperalgesia in susceptible BALB/c mice accompanied by up-regulation of the pro-inflammatory cytokines IL-1β and IL-6. Interleukin-13 (IL-13) has been shown to reduce this hyperalgesia (despite increased levels of IL-6) and the levels of IL-1β during and after the treatment period. These findings favor the cytokine cascade leading to the production of sympathetic amines (involving TNF-α and KC) over prostaglandins (involving IL-lβ and IL-6) as the final mediators of hyperalgesia. The aim of this study was to investigate the effect of daily treatment with the β-blockers atenolol on L. major-induced inflammation in mice with respect to hyperalgesia as well as the levels of TNF-α and KC (the analog of IL-8 in mice). Our data demonstrates that atenolol is able to reduce the L. major induced sustained peripheral hyperalgesia, which does not seem to involve a direct role for neither IL-lβ nor KC. Moreover, our results show that TNF-α may play a pivotal and direct role in sensitizing the peripheral nerve endings (nociceptors) since its level was reduced during the period of atenolol treatment, which correlates well with the reduction of the observed peripheral, but not central, hyperalgesia. These findings contribute to a better understanding of the cytokine cascade leading to hyperalgesia and may lead to the development of new and more efficient medications for many types of pain. PMID:26913003

  15. Mechanics of Dynamin-Mediated Membrane Fission

    PubMed Central

    Morlot, Sandrine; Roux, Aurélien

    2013-01-01

    In eukaryotic cells, membrane compartments are split into two by membrane fission. This ensures discontinuity of membrane containers and thus proper compartmentalization. The first proteic machinery implicated in catalyzing membrane fission was dynamin. Dynamin forms helical collars at the neck of endocytic buds. This structural feature suggested that the helix of dynamin could constrict in order to promote fission of the enclosed membrane. However, verifying this hypothesis revealed itself to be a challenge, which inspired many in vitro and in vivo studies. The primary goal of this review is to discuss recent structural and physical data from biophysical studies that have refined our understanding of the dynamin mechanism. In addition to the constriction hypothesis, other models have been proposed to explain how dynamin induces membrane fission. We present experimental data supporting these various models and assess which model is the most probable. PMID:23541160

  16. The degree of acute descending control of spinal nociception in an area of primary hyperalgesia is dependent on the peripheral domain of afferent input

    PubMed Central

    Drake, Robert A R; Hulse, Richard P; Lumb, Bridget M; Donaldson, Lucy F

    2014-01-01

    Descending controls of spinal nociceptive processing play a critical role in the development of inflammatory hyperalgesia. Acute peripheral nociceptor sensitization drives spinal sensitization and activates spino–supraspinal–spinal loops leading to descending inhibitory and facilitatory controls of spinal neuronal activity that further modify the extent and degree of the pain state. The afferent inputs from hairy and glabrous skin are distinct with respect to both the profile of primary afferent classes and the degree of their peripheral sensitization. It is not known whether these differences in afferent input differentially engage descending control systems to different extents or in different ways. Injection of complete Freund's adjuvant resulted in inflammation and swelling of hairy hind foot skin in rats, a transient thermal hyperalgesia lasting <2 h, and longlasting primary mechanical hyperalgesia (≥7 days). Much longer lasting thermal hyperalgesia was apparent in glabrous skin (1 h to >72 h). In hairy skin, transient hyperalgesia was associated with sensitization of withdrawal reflexes to thermal activation of either A- or C-nociceptors. The transience of the hyperalgesia was attributable to a rapidly engaged descending inhibitory noradrenergic mechanism, which affected withdrawal responses to both A- and C-nociceptor activation and this could be reversed by intrathecal administration of yohimbine (α-2-adrenoceptor antagonist). In glabrous skin, yohimbine had no effect on an equivalent thermal inflammatory hyperalgesia. We conclude that acute inflammation and peripheral nociceptor sensitization in hind foot hairy skin, but not glabrous skin, rapidly activates a descending inhibitory noradrenergic system. This may result from differences in the engagement of descending control systems following sensitization of different primary afferent classes that innervate glabrous and hairy skin. PMID:24879873

  17. Distinct Neural Mechanisms Mediate Olfactory Memory Formation at Different Timescales

    ERIC Educational Resources Information Center

    McNamara, Ann Marie; Magidson, Phillip D.; Linster, Christiane; Wilson, Donald A.; Cleland, Thomas A.

    2008-01-01

    Habituation is one of the oldest forms of learning, broadly expressed across sensory systems and taxa. Here, we demonstrate that olfactory habituation induced at different timescales (comprising different odor exposure and intertrial interval durations) is mediated by different neural mechanisms. First, the persistence of habituation memory is…

  18. Nocebo hyperalgesia induced by social observational learning.

    PubMed

    Vögtle, Elisabeth; Barke, Antonia; Kröner-Herwig, Birgit

    2013-08-01

    Nocebo effects can be acquired by verbal suggestion, but it is unknown whether they can be induced through observational learning and whether they are influenced by factors known to influence pain perception, such as pain anxiety or pain catastrophizing. Eighty-five female students (aged 22.5 ± 4.4 years) were randomly assigned to one of three conditions. Participants in the control condition (CC) received information that an ointment had no effect on pain perception. Participants in the verbal suggestion condition (VSC) received information that it increased pain sensitivity. Participants in the social observational learning condition (OLC) watched a video in which a model displayed more pain when ointment was applied. Subsequently, all participants received three pressure pain stimuli (60 seconds) on each hand. On one hand, the ointment was applied prior to the stimulation. Numerical pain ratings were collected at 20-second intervals during pain stimulation. The participants filled in questionnaires regarding pain-related attitudes (Pain Anxiety Symptoms Scale, Pain Catastrophizing Scale, and Somatosensory Amplification Scale). Participants in the OLC showed higher pain ratings with than without ointment. Pain ratings within the CC and the VSC were at the same level with and without ointment. In the VSC, the pain ratings were higher than in the CC with and without ointment. The nocebo response correlated with pain catastrophizing but not with pain anxiety or somatosensory amplification. A nocebo response to pressure pain was induced by observational learning but not by verbal suggestion. This finding highlights the importance of investigating the influence of observational learning on nocebo hyperalgesia. PMID:23707275

  19. A novel p38 MAPK docking groove-targeted compound is a potent inhibitor of inflammatory hyperalgesia

    PubMed Central

    Willemen, Hanneke L.D.M.; Campos, Pedro M.; Lucas, Elisa; Morreale, Antonio; Gil-Redondo, Rubén; Agut, Juan; González, Florenci V.; Ramos, Paula; Heijnen, Cobi; Mayor, Federico; Kavelaars, Annemieke; Murga, Cristina

    2014-01-01

    Synopsis The mitogen activated protein kinase (MAPK) p38 is an important mediator of inflammation and of inflammatory and neuropathic pain. We recently described that docking-groove dependent interactions are important for p38 MAPK-mediated signal transduction. Thus, virtual screening was performed to identify putative docking groove-targeted p38 MAPK inhibitors. Several compounds of the benzooxadiazol family were identified with low micromolar inhibitory activity both in a p38 MAPK activity assay, and in THP-1 human monocytes acting as inhibitors of LPS-induced TNFα secretion. Positions 2 and 5 in the phenyl ring are essential for the described inhibitory activity with a chloride in position 5 and a methyl-group in position 2 yielding the best results with an IC50 of 1.8 μM (FGA-19 compound). Notably, FGA-19 exerted a potent and long-lasting analgesic effect in vivo when tested in a mouse model of inflammatory hyperalgesia. A single intrathecal injection of FGA-19 completely resolved hyperalgesia, being ten times as potent and displaying longer lasting effects than the established p38 MAPK inhibitor SB239063. FGA-19 also reversed persistent pain in a model of post-inflammatory hyperalgesia (in LysM-GRK2+/− mice). These potent in vivo effects put forward p38 MAPK docking-site targeted inhibitors as a potential novel strategy for the treatment of inflammatory pain. PMID:24517375

  20. Contribution of mast cells and snake venom metalloproteinases to the hyperalgesia induced by Bothrops jararaca venom in rats.

    PubMed

    Bonavita, André Gustavo C; da Costa, Aline S; Pires, Ana Lucia A; Neves-Ferreira, Ana G C; Perales, Jonas; Cordeiro, Renato S B; Martins, Marco A; e Silva, Patrícia M R

    2006-06-15

    Bothrops jararaca venom (Bjv) is known to induce local inflammation and severe pain. Since, mast cells are able to secrete mediators involved in algesic processes, in this study we examined the putative role of these cells in the hyperalgesia triggered by Bjv in the rat paw. We noted that treatment with mast cell stabilizer sodium cromoglicate as well as with histamine and 5-hydroxytriptamine receptor antagonists meclizine and methysergide, respectively, inhibited the Bjv-induced hyperalgesia. In addition, we showed that stimulation of isolated rat peritoneal mast cells with Bjv in vitro resulted in the release of stored and neo-generated inflammatory mediators such as histamine and leukotriene C(4), respectively. Bjv-induced histamine secretion was clearly sensitive to treatment with sodium cromoglicate and sodium nedocromil. We further observed that metalloproteinase inhibitors 1,10-phenantroline and DM43 inhibited mast cell degranulation in vitro, under conditions where inhibitors of phospholipase A(2) as well as of serine- and cysteine-proteinases were inactive. Altogether, our findings indicate that mast cells seem to contribute to the hyperalgesia caused by Bjv in the rat paw, and also provide evidence that this response might be dependent on the ability of the Bjv to activate directly mast cells. PMID:16730041

  1. Activation of Cannabinoid CB2 receptors Reduces Hyperalgesia in an Experimental Autoimmune Encephalomyelitis Mouse Model of Multiple Sclerosis

    PubMed Central

    Fu, Weisi; Taylor, Bradley K.

    2015-01-01

    Clinical trials investigating the analgesic efficacy of cannabinoids in multiple sclerosis have yielded mixed results, possibly due to psychotropic side effects mediated by cannabinoid CB1 receptors. We hypothesized that a CB2-specific agonist (JWH-133) would decrease hyperalgesia in an experimental autoimmune encephalomyelitis mouse model of multiple sclerosis. 4 weeks after induction of experimental autoimmune encephalomyelitis, we found that intrathecal administration of JWH-133 (10–100 μg) dose-dependently reduced both mechanical and cold hypersensitivity without producing signs of sedation or ataxia. The anti-hyperalgesic effects of JWH-133 could be dose-dependently prevented by intrathecal co-administration of the CB2 antagonist, AM-630 (1–3 μg). Our results suggest that JWH-133 acts at CB2 receptors, most likely within the dorsal horn of the spinal cord, to suppress the hypersensitivity associated with experimental autoimmune encephalomyelitis. These are the first pre-clinical studies to directly promote CB2 as a promising target for the treatment of central pain in an animal model of multiple sclerosis. PMID:25849525

  2. Intact subepidermal nerve fibers mediate mechanical hypersensitivity via the activation of protein kinase C gamma in spared nerve injury

    PubMed Central

    Ko, Miau-Hwa; Yang, Ming-Ling; Youn, Su-Chung; Tseng, To-Jung

    2016-01-01

    Background Spared nerve injury is an important neuropathic pain model for investigating the role of intact primary afferents in the skin on pain hypersensitivity. However, potential cellular mechanisms remain poorly understood. In phosphoinositide-3 kinase pathway, pyruvate dehydrogenase kinase 1 (PDK1) participates in the regulation of neuronal plasticity for central sensitization. The downstream cascades of PDK1 include: (1) protein kinase C gamma (PKCγ) controls the trafficking and phosphorylation of ionotropic glutamate receptor; (2) protein kinase B (Akt)/the mammalian target of rapamycin (mTOR) signaling is responsible for local protein synthesis. Under these statements, we therefore hypothesized that an increase of PKCγ activation and mTOR-dependent PKCγ synthesis in intact primary afferents after SNI might contribute to pain hypersensitivity. Results The variants of spared nerve injury were performed in Sprague-Dawley rats by transecting any two of the three branches of the sciatic nerve, leaving only one branch intact. Following SNIt (spared tibial branch), mechanical hyperalgesia and mechanical allodynia, but not thermal hyperalgesia, were significantly induced. In the first footpad, normal epidermal innervations were verified by the protein gene product 9.5 (PGP9.5)- and growth-associated protein 43 (GAP43)-immunoreactive (IR) intraepidermal nerve fibers (IENFs) densities. Furthermore, the rapid increases of phospho-PKCγ- and phospho-mTOR-IR subepidermal nerve fibers (SENFs) areas were distinct gathered from the results of PGP9.5-, GAP43-, and neurofilament 200 (NF200)-IR SENFs areas. The efficacy of PKC inhibitor (GF 109203X) or mTOR complex 1 inhibitor (rapamycin) for attenuating mechanical hyperalgesia and mechanical allodynia by intraplantar injection was dose-dependent. Conclusions From results obtained in this study, we strongly recommend that the intact SENFs persistently increase PKCγ activation and mTOR-dependent PKCγ synthesis participate

  3. Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism.

    PubMed

    Gegear, Robert J; Foley, Lauren E; Casselman, Amy; Reppert, Steven M

    2010-02-11

    Understanding the biophysical basis of animal magnetoreception has been one of the greatest challenges in sensory biology. Recently it was discovered that the light-dependent magnetic sense of Drosophila melanogaster is mediated by the ultraviolet (UV)-A/blue light photoreceptor cryptochrome (Cry). Here we show, using a transgenic approach, that the photoreceptive, Drosophila-like type 1 Cry and the transcriptionally repressive, vertebrate-like type 2 Cry of the monarch butterfly (Danaus plexippus) can both function in the magnetoreception system of Drosophila and require UV-A/blue light (wavelength below 420 nm) to do so. The lack of magnetic responses for both Cry types at wavelengths above 420 nm does not fit the widely held view that tryptophan triad-generated radical pairs mediate the ability of Cry to sense a magnetic field. We bolster this assessment by using a mutant form of Drosophila and monarch type 1 Cry and confirm that the tryptophan triad pathway is not crucial in magnetic transduction. Together, these results suggest that animal Crys mediate light-dependent magnetoreception through an unconventional photochemical mechanism. This work emphasizes the utility of Drosophila transgenesis for elucidating the precise mechanisms of Cry-mediated magnetosensitivity in insects and also in vertebrates such as migrating birds. PMID:20098414

  4. Molecular mechanisms of IgE mediated food allergy.

    PubMed

    Kumar, Sandeep; Verma, Alok Kumar; Das, Mukul; Dwivedi, Premendra D

    2012-08-01

    The purpose of this review is to collate current knowledge and recent advances in molecular mechanism behind the immediate type hypersensitivity of foods. Food allergy is a growing concern of human health in developed as well as developing countries now days. Food allergic reactions are mostly IgE mediated and also known as immediate type hypersensitivity or type I reaction. This review encompasses a wide range of molecular events during IgE mediated reactions like primary exposure of allergens, processing of allergens by antigen presenting cells, role of transcription factors like GATA-3, STAT-6, NF-AT, c-maf, c-kit and NF-κB, Treg cells, toll like receptors, cytokines and chemokines, class switch to IgE, FcεR1 receptor, priming of IgE on mast cells or basophils, signaling events followed by secondary exposure of allergens, degranulation and release of mediators like leukotrienes, histamines, prostaglandins, β-hexosaminidase and ultimately anaphylaxis. This review may be helpful to beginners as well as experts working in the field of allergy and immunology because of the stepwise explanations of molecular mechanisms involved in IgE mediated reactions. PMID:22668720

  5. Immune-mediated mechanism for thrombocytopenia after Loxosceles spider bite.

    PubMed

    Levin, Carina; Bonstein, Lilach; Lauterbach, Roy; Mader, Rivka; Rozemman, Dganit; Koren, Ariel

    2014-08-01

    Loxoscelism, characterized by high fever, vomiting, malaise, a dermonecrotic lesion, and thrombocytopenia, was diagnosed in a 3-year-old female. Clinical laboratory and dermatological signs are described. Blood test showed a transient hypercoagulable state and the presence of IgG antibodies against platelets, suggesting an immune-mediated mechanism for platelet destruction, in addition to the direct toxic effect of the spider venom. The finding of platelet antibodies after a Loxosceles spider bite has not been previously reported. PMID:24497468

  6. Effects of systemic non-steroidal anti-inflammatory drugs on nociception during tail ischaemia and on reperfusion hyperalgesia in rats.

    PubMed Central

    Gelgor, L.; Butkow, N.; Mitchell, D.

    1992-01-01

    1. We have investigated the effects of five non-steroidal anti-inflammatory drugs (NSAIDs) on nociception during ischaemia and on reperfusion hyperalgesia in rats. 2. We induced tail ischaemia in conscious rats by applying a tourniquet at the base of the tail until the rats exhibited co-ordinated escape behaviour when we released the tourniquet. 3. We assessed hyperalgesia by measuring the tail flick latency following tail immersion in water at 49 degrees C, before applying and immediately after releasing the tourniquet, and then at 30 min intervals for 2 h. 4. Intraperitoneal injection of NSAIDs prior to applying the tourniquet had no effect on the co-ordinated escape behaviour during ischaemia, nor on tail flick latency in the absence of prior ischaemia. However all the drugs attenuated reperfusion hyperalgesia in a log dose-dependent manner. Doses required to abolish hyperalgesia, were indomethacin 5 mg kg-1, diclofenac sodium 42 mg kg-1, ibuprofen 54 mg kg-1, dipyrone 168 mg kg-1 and paracetamol 170 mg kg-1. 5. We conclude that the mechanisms underlying nociception during ischaemia are not the same as those underlying reperfusion hyperalgesia. Moreover our procedure provides a rapid and more humane method for measuring the antinociceptive potency of NSAIDs. PMID:1559131

  7. Separating monocular and binocular neural mechanisms mediating chromatic contextual interactions.

    PubMed

    D'Antona, Anthony D; Christiansen, Jens H; Shevell, Steven K

    2014-01-01

    When seen in isolation, a light that varies in chromaticity over time is perceived to oscillate in color. Perception of that same time-varying light may be altered by a surrounding light that is also temporally varying in chromaticity. The neural mechanisms that mediate these contextual interactions are the focus of this article. Observers viewed a central test stimulus that varied in chromaticity over time within a larger surround that also varied in chromaticity at the same temporal frequency. Center and surround were presented either to the same eye (monocular condition) or to opposite eyes (dichoptic condition) at the same frequency (3.125, 6.25, or 9.375 Hz). Relative phase between center and surround modulation was varied. In both the monocular and dichoptic conditions, the perceived modulation depth of the central light depended on the relative phase of the surround. A simple model implementing a linear combination of center and surround modulation fit the measurements well. At the lowest temporal frequency (3.125 Hz), the surround's influence was virtually identical for monocular and dichoptic conditions, suggesting that at this frequency, the surround's influence is mediated primarily by a binocular neural mechanism. At higher frequencies, the surround's influence was greater for the monocular condition than for the dichoptic condition, and this difference increased with temporal frequency. Our findings show that two separate neural mechanisms mediate chromatic contextual interactions: one binocular and dominant at lower temporal frequencies and the other monocular and dominant at higher frequencies (6-10 Hz). PMID:24744449

  8. Novel Lipid Mediators and Resolution Mechanisms in Acute Inflammation

    PubMed Central

    Serhan, Charles N.

    2010-01-01

    Because inflammation is appreciated as a unifying basis of many widely occurring diseases, the mechanisms involved in its natural resolution are of considerable interest. Using contained, self-limited inflammatory exudates and a systems approach, novel lipid-derived mediators and pathways were uncovered in the resolution of inflammatory exudates. These new families of local mediators control both the duration and magnitude of acute inflammation as well as the return of the site to homeostasis in the process of catabasis. This new genus of specialized proresolving mediators (SPM) includes essential fatty acid–derived lipoxins, resolvins, protectins, and, most recently, maresins. These families were named based on their unique structures and potent stereoselective actions. The temporally initiated biosynthesis of SPM and their direct impact on leukocyte trafficking and macrophage-directed clearance mechanisms provide clear evidence that resolution is an active, programmed response at the tissue level. Moreover, SPM that possess anti-inflammatory (ie, limiting PMN infiltration) and proresolving (enhance macrophage uptake and clearance of apoptotic PMN and microbial particles) actions as well as stimulating mucosal antimicrobial responses demonstrate that anti-inflammation and proresolution are different responses of the host and novel defining properties of these molecules. The mapping of new resolution circuits has opened the possibility for understanding mechanisms that lead from acute to chronic inflammation, or to the resolution thereof, as well as to potential, resolution-based immunopharmacological therapies. PMID:20813960

  9. Ursolic acid prevents augmented peripheral inflammation and inflammatory hyperalgesia in high-fat diet-induced obese rats by restoring downregulated spinal PPARα.

    PubMed

    Zhang, Yanan; Song, Chengwei; Li, Haiou; Hou, Jingdong; Li, Dongliang

    2016-06-01

    Obesity is a risk factor for several pain syndromes and is associated with increased pain sensitivity. Evidence suggests that obesity causes the downregulation of peroxisome proliferator‑activated receptor (PPAR)α in the spinal cord, contributing to augmented peripheral edema and inflammatory hyperalgesia. Ursolic acid (UA), a natural pentacyclic triterpenoid carboxylic acid, has been shown to upregulate PPARα in the peripheral tissues of obese animals. The present study hypothesized that UA prevents augmented peripheral inflammation and inflammatory hyperalgesia in obesity by restoring downregulated spinal PPARα. The present study demonstrated that Sprague‑Dawley rats fed a high‑fat diet (HFD) for 12 weeks developed obesity and metabolic disorder. Following carrageenan injection, the HFD rats exhibited increased thermal hyperalgesia and paw edema, compared with the rats fed a low‑fat diet. Molecular investigations revealed that the HFD rats exhibited decreased PPARα activity, and exaggerated expression of inflammatory mediators and nuclear factor‑kB activity in the spinal cord in response to carrageenan. Oral administration of UA ameliorated obesity and metabolic disorder, and prevented increased thermal hyperalgesia and paw edema in the HFD rats. Additionally, UA normalized PPARα activity and inhibited the exaggerated spinal cord inflammatory response to carrageenan. Although the knockdown of spinal PPARα with small interfering RNA following the administration of UA did not alter obesity or metabolic parameters, it eradicated the beneficial effects of UA on thermal hyperalgesia and paw edema, and reversed the spinal cord inflammatory response. These results suggested that the systemic administration of UA inhibited the exaggerated spinal cord inflammatory response to peripheral inflammatory stimulation in HFD‑induced obesity by restoring downregulated spinal PPARα, preventing peripheral inflammation and inflammatory hyperalgesia. UA may be a

  10. Shugan-decoction relieves visceral hyperalgesia and reduces TRPV1 and SP colon expression

    PubMed Central

    Shang, Jing-Juan; Yuan, Jian-Ye; Xu, Hui; Tang, Rong-Zhu; Dong, Yue-Bin; Xie, Jian-Qun

    2013-01-01

    .001); however, the low-dose SGD treatment produced no significant effect on the WAS-reduced PPT (198.3 ± 1.78 mmHg, P > 0.05). These trends corresponded to the differential expressions observed for both TRPV1 protein (mid-dose: 1.64 ± 0.08 and high-dose: 1.69 ± 0.12 vs untreated model: 3.65 ± 0.32, P < 0.001) and mRNA (0.44 ± 0.16 and 0.15 ± 0.03 vs 1.39 ± 0.15, P < 0.001) and SP protein (0.99 ± 0.20 and 1.03 ± 0.23 vs 2.03 ± 0.12, P < 0.01) and mRNA (1.64 ± 0.19 and 1.32 ± 0.14 vs 2.60 ± 0.33, P < 0.05). These differential expressions of TRPV1 and SP related to mid- and high-dose SGD treatments were statistically similar to the changes induced by dicetel treatment. No signs of overt damage to the rat system were observed for any of the SGD dosages. CONCLUSION: Shugan-decoction can reduce chronic stress-induced visceral hypersensitivity in rats, and the regulatory mechanism may involve mediating the expressions of TRPV1 and SP in colon tissues. PMID:24307802

  11. Mitotic wavefronts mediated by mechanical signaling in early Drosophila embryos

    NASA Astrophysics Data System (ADS)

    Kang, Louis; Idema, Timon; Liu, Andrea; Lubensky, Tom

    2013-03-01

    Mitosis in the early Drosophila embryo demonstrates spatial and temporal correlations in the form of wavefronts that travel across the embryo in each cell cycle. This coordinated phenomenon requires a signaling mechanism, which we suggest is mechanical in origin. We have constructed a theoretical model that supports nonlinear wavefront propagation in a mechanically-excitable medium. Previously, we have shown that this model captures quantitatively the wavefront speed as it varies with cell cycle number, for reasonable values of the elastic moduli and damping coefficient of the medium. Now we show that our model also captures the displacements of cell nuclei in the embryo in response to the traveling wavefront. This new result further supports that mechanical signaling may play an important role in mediating mitotic wavefronts.

  12. Pain referral and regional deep tissue hyperalgesia in experimental human hip pain models.

    PubMed

    Izumi, Masashi; Petersen, Kristian Kjær; Arendt-Nielsen, Lars; Graven-Nielsen, Thomas

    2014-04-01

    Hip disorder patients typically present with extensive pain referral and hyperalgesia. To better understand underlying mechanisms, an experimental hip pain model was established in which pain referrals and hyperalgesia could be studied under standardized conditions. In 16 healthy subjects, pain was induced by hypertonic saline injection into the gluteus medius tendon (GMT), adductor longus tendon (ALT), or gluteus medius muscle (GMM). Isotonic saline was injected contralaterally as control. Pain intensity was assessed on a visual analogue scale (VAS), and subjects mapped the pain distribution. Before, during, and after injections, passive hip joint pain provocation tests were completed, together with quantitative sensory testing as follows: pressure pain thresholds (PPTs), cuff algometry pain thresholds (cuff PPTs), cutaneous pin-prick sensitivity, and thermal pain thresholds. Hypertonic saline injected into the GMT resulted in higher VAS scores than hypertonic injections into the ALT and GMM (P<.05). Referred pain areas spread to larger parts of the leg after GMT and GMM injections compared with more regionalized pain pattern after ALT injections (P<.05). PPTs at the injection site were decreased after hypertonic saline injections into GMT and GMM compared with baseline, ALT injections, and isotonic saline. Cuff PPTs from the thigh were decreased after hypertonic saline injections into the ALT compared with baseline, GMT injections, and isotonic saline (P<.05). More subjects had positive joint pain provocation tests after hypertonic compared with isotonic saline injections (P<.05), indicating that this provocation test also assessed hyperalgesia in extra-articular soft tissues. The experimental models may open for better understanding of pain mechanisms associated with painful hip disorders. PMID:24447510

  13. Hyperalgesia due to nerve injury: role of neutrophils.

    PubMed

    Perkins, N M; Tracey, D J

    2000-01-01

    The hypothesis that the early inflammatory cell, the neutrophil, contributes to the hyperalgesia resulting from peripheral nerve injury was tested in rats in which the sciatic nerve was partially transected on one side. The extent and time-course of neutrophilic infiltration of the sciatic nerve and innervated paw skin after partial nerve damage was characterized using immunocytochemistry. The number of endoneurial neutrophils was significantly elevated in sections of operated nerve compared to sections of sham-operated nerve for the entire period studied, i.e. up to seven days post-surgery. This considerable elevation in endoneurial neutrophil numbers was only observed at the site of nerve injury. Depletion of circulating neutrophils at the time of nerve injury significantly attenuated the induction of hyperalgesia. However, depletion of circulating neutrophils at day 8 post-injury did not alleviate hyperalgesia after its normal induction. It is concluded that endoneurial accumulation of neutrophils at the site of peripheral nerve injury is important in the early genesis of the resultant hyperalgesia. The findings support the notion that a neuroimmune interaction occurs as a result of peripheral nerve injury and is important in the subsequent development of neuropathic pain. PMID:11113323

  14. Intraganglionar resiniferatoxin prevents orofacial inflammatory and neuropathic hyperalgesia.

    PubMed

    Cruz, Lizane S; Kopruszinski, Caroline M; Chichorro, Juliana G

    2014-04-01

    Trigeminal ganglion C-fiber neurons bearing transient receptor potential vanilloid-1 (TRPV1) channels are selectively destroyed by resiniferatoxin (RTX), a potent capsaicin analogue. The current study assessed the effect of an RTX injection (200 ng/4 μl) into the trigeminal ganglion in inflammatory and neuropathic rat models of orofacial thermal hyperalgesia. Intraganglionar RTX injection resulted in trigeminal ganglion C-fiber deletion, which was confirmed by the capsaicin eye wipes test, performed 6 days after the injection. The nociceptive responses induced by 2.5% formalin injected into the orofacial region were unchanged by a previous intraganglionar RTX injection. However, orofacial heat and cold hyperalgesia, induced by carrageenan injected into the upper lip (50 µg/50 μl), was abolished by previous intraganglionar RTX treatment. In addition, the development of orofacial heat and cold hyperalgesia after constriction of the infraorbital nerve was prevented by previous RTX treatment. Thus, trigeminal ganglion neurons expressing TRPV1 are crucial for the development of orofacial inflammatory and neuropathic thermal hyperalgesia. PMID:24557321

  15. Pathogenesis and mechanisms of antibody-mediated hemolysis

    PubMed Central

    Flegel, Willy A

    2015-01-01

    Background The clinical consequences of antibodies to red blood cells (RBC) have been studied for a century. Most clinically relevant antibodies can be detected by sensitive in vitro assays. Several mechanisms of antibody-mediated hemolysis are well understood. Such hemolysis following transfusion is reliably avoided in a donor/recipient pair, if one individual is negative for the cognate antigen to which the other has the antibody. Study design and results Mechanisms of antibody-mediated hemolysis were reviewed based on a presentation at the Strategies to Address Hemolytic Complications of Immune Globulin Infusions Workshop addressing intravenous immunoglobulin (IVIG) and ABO antibodies. The presented topics included the rates of intravascular and extravascular hemolysis; IgM and IgG isoagglutinins; auto- and alloantibodies; antibody specificity; A, B, A,B and A1 antigens; A1 versus A2 phenotypes; monocytes/macrophages, other immune cells and complement; monocyte monolayer assay (MMA); antibody-dependent cell-mediated cytotoxicity (ADCC); and transfusion reactions due to ABO and other antibodies. Conclusion Several clinically relevant questions remained unresolved, and diagnostic tools were lacking to routinely and reliably predict the clinical consequences of RBC antibodies. Most hemolytic transfusion reactions associated with IVIG were due to ABO antibodies. Reducing the titers of such antibodies in IVIG may lower the frequency of this kind of adverse event. The only way to stop these events is to have no anti-A or anti-B antibodies in the IVIG products. PMID:26174897

  16. Resveratrol attenuates inflammation-induced hyperexcitability of trigeminal spinal nucleus caudalis neurons associated with hyperalgesia in rats

    PubMed Central

    Sekiguchi, Kenta; Takehana, Shiori; Shibuya, Eri; Matsuzawa, Nichiwa; Hidaka, Shiori; Kanai, Yurie; Inoue, Maki; Kubota, Yoshiko; Shimazu, Yoshihito

    2016-01-01

    Background Resveratrol, a component of red wine, has been reported to decrease prostaglandin E2 production by inhibiting the cyclooxygenase-2 cascade and to modulate various voltage-dependent ion channels, suggesting that resveratrol could attenuate inflammatory hyperalgesia. However, the effects of resveratrol on inflammation-induced hyperexcitability of nociceptive neurons in vivo remain to be determined. Thus, the aim of the present study was to determine whether daily systemic administration of resveratrol to rats attenuates the inflammation-induced hyperexcitability of spinal trigeminal nucleus caudalis wide-dynamic range neurons associated with hyperalgesia. Results Inflammation was induced by injection of complete Freund’s adjuvant into the whisker pad. The threshold of escape from mechanical stimulation applied to whisker pad in inflamed rats was significantly lower than in control rats. The decreased mechanical threshold in inflamed rats was restored to control levels by daily systemic administration of resveratrol (2 mg/kg, i.p.). The mean discharge frequency of spinal trigeminal nucleus caudalis wide-dynamic range neurons to both nonnoxious and noxious mechanical stimuli in inflamed rats was significantly decreased after resveratrol administration. In addition, the increased mean spontaneous discharge of spinal trigeminal nucleus caudalis wide-dynamic range neurons in inflamed rats was significantly decreased after resveratrol administration. Similarly, resveratrol significantly diminished noxious pinch-evoked mean after discharge frequency and occurrence in inflamed rats. Finally, resveratrol restored the expanded mean size of the receptive field in inflamed rats to control levels. Conclusion These results suggest that chronic administration of resveratrol attenuates inflammation-induced mechanical inflammatory hyperalgesia and that this effect is due primarily to the suppression of spinal trigeminal nucleus caudalis wide dynamic range neuron

  17. Chronic infection by Leishmania amazonensis mediated through MAPK ERK mechanisms

    PubMed Central

    Martinez, Pedro A.; Petersen, Christine A.

    2014-01-01

    Leishmania amazonensis is an intracellular protozoan parasite responsible for chronic cutaneous leishmaniasis (CL). CL is a neglected tropical disease responsible for infecting millions of people worldwide. L. amazonensis promotes alteration of various signaling pathways that are essential for host cell survival. Specifically, through parasite-mediated phosphorylation of extracellular signal regulated kinase (ERK), L. amazonensis inhibits cell-mediated parasite killing and promotes its own survival by co-opting multiple host cell functions. In this review we highlight Leishmania-host cell signaling alterations focusing on those specific to 1) motor proteins, 2) prevention of NADPH subunit phosphorylation impairing reactive oxygen species production (ROS), and 3) localized endosomal signaling to up-regulate ERK phosphorylation. This review will focus upon mechanisms and possible explanations as to how Leishmania spp. evades the various layers of defense employed by the host immune response. PMID:24838145

  18. Mechanically Mediated Microwave Frequency Conversion in the Quantum Regime

    NASA Astrophysics Data System (ADS)

    Lecocq, F.; Clark, J. B.; Simmonds, R. W.; Aumentado, J.; Teufel, J. D.

    2016-01-01

    We report the observation of efficient and low-noise frequency conversion between two microwave modes, mediated by the motion of a mechanical resonator subjected to radiation pressure. We achieve coherent conversion of more than 1012 photons/s with a 95% efficiency and a 14 kHz bandwidth. With less than 10-1 photons.s-1.Hz-1 of added noise, this optomechanical frequency converter is suitable for quantum state transduction. We show the ability to operate this converter as a tunable beam splitter, with direct applications for photon routing and communication through complex quantum networks.

  19. Dispositional mindfulness in trauma recovery: Prospective relations and mediating mechanisms.

    PubMed

    Nitzan-Assayag, Yaara; Aderka, Idan M; Bernstein, Amit

    2015-12-01

    This study examined the protective properties and candidate mediating processes (cognitive fusion and cognitive suppression) linking dispositional mindfulness to distal risk factors (negative affect, anxiety sensitivity, rumination) and psychopathology symptom outcomes (depression and posttraumatic stress symptoms) following trauma exposure. To do so, a community-based sample of adults was longitudinally studied in the six-months following exposure--within 30-days (T1), 3-months (T2), and 6-months (T3)--to a shared disaster-related potentially traumatic event (PTE). Specifically, we found that cognitive fusion predicted, and mediated, the effect of mindfulness on outcomes related to distress post-trauma including negative affect, depression and posttraumatic stress symptoms. Complementary to these effects, we found that cognitive suppression predicted, and mediated, the effect of mindfulness on distal risk factors linked to negative self-referential processes including rumination and anxiety sensitivity. Findings are discussed with respect to their theoretical and clinical implications for the potential role and mechanisms of mindfulness in recovery following trauma. PMID:26401969

  20. Mechanism and regulation of the nonsense-mediated decay pathway

    PubMed Central

    Hug, Nele; Longman, Dasa; Cáceres, Javier F.

    2016-01-01

    The Nonsense-mediated mRNA decay (NMD) pathway selectively degrades mRNAs harboring premature termination codons (PTCs) but also regulates the abundance of a large number of cellular RNAs. The central role of NMD in the control of gene expression requires the existence of buffering mechanisms that tightly regulate the magnitude of this pathway. Here, we will focus on the mechanism of NMD with an emphasis on the role of RNA helicases in the transition from NMD complexes that recognize a PTC to those that promote mRNA decay. We will also review recent strategies aimed at uncovering novel trans-acting factors and their functional role in the NMD pathway. Finally, we will describe recent progress in the study of the physiological role of the NMD response. PMID:26773057

  1. Molecular Mechanisms of Treg-Mediated T Cell Suppression

    PubMed Central

    Schmidt, Angelika; Oberle, Nina; Krammer, Peter H.

    2012-01-01

    CD4+CD25highFoxp3+ regulatory T cells (Tregs) can suppress other immune cells and, thus, are critical mediators of peripheral self-tolerance. On the one hand, Tregs avert autoimmune disease and allergies. On the other hand, Tregs can prevent immune reactions against tumors and pathogens. Despite the importance of Tregs, the molecular mechanisms of suppression remain incompletely understood and controversial. Proliferation and cytokine production of CD4+CD25− conventional T cells (Tcons) can be inhibited directly by Tregs. In addition, Tregs can indirectly suppress Tcon activation via inhibition of the stimulatory capacity of antigen presenting cells. Direct suppression of Tcons by Tregs can involve immunosuppressive soluble factors or cell contact. Different mechanisms of suppression have been described, so far with no consensus on one universal mechanism. Controversies might be explained by the fact that different mechanisms may operate depending on the site of the immune reaction, on the type and activation state of the suppressed target cell as well as on the Treg activation status. Further, inhibition of T cell effector function can occur independently of suppression of proliferation. In this review, we summarize the described molecular mechanisms of suppression with a particular focus on suppression of Tcons and rapid suppression of T cell receptor-induced calcium (Ca2+), NFAT, and NF-κB signaling in Tcons by Tregs. PMID:22566933

  2. The evolution of primary hyperalgesia in orthopedic surgery: quantitative sensory testing and clinical evaluation before and after total knee arthroplasty

    PubMed Central

    Martinez, Valéria; Fletcher, Dominique; Bouhassira, Didier; Sessler, Daniel I.; Chauvin, Marcel

    2007-01-01

    Background Quantitative sensory testing (QST), which allows a better characterization of sensory deficits and painful symptoms, may offer additional information on the pathophysiology of postoperative pain. Methodology Twenty patients scheduled for total knee anthroplasty were evaluated clinically and with QST before surgery, at one and four days, and at one and four months after surgery. Clinical evaluation included preoperative pain and inflammation of operative knee, postoperative assessment of pain at rest and during movement (Visual Analog Scale score), cumulative morphine consumption, and circumference and temperature of both knees. QST included thermal and mechanical (pressure) pain threshold measurements and assessment of responses to suprathreshold stimuli. Brush-evoked allodynia was also evaluated. Measurements were taken on the operative knee, contra lateral knee, and on the hand as a control site. Results All patients had prolonged and severe pain before surgery and inflammation of operative knee. Preoperative OST provided evidence of heat hyperalgesia in the inflammatory area on the operative knee, but absence of punctate or brush-evoked allodynia in the adjacent non inflamed area. Patients had intense postoperative pain, mostly induced by movement. Primary heat hyperalgesia was present on the operative knee on the first and fourth days after surgery, and was associated with punctate mechanical allodynia in the inflammatory area, but not in the adjacent non inflamed area. Postoperative morphine consumption was correlated with preoperative heat hyperalgesia (r=0.63; P=0.01). QST was normalyzed at the 4-month evaluation and only 4 patients had moderate knee pain induced by movement at that time. Conclusion Heat hyperalgesia was the predominant OST symptom associated with perioperative pain after total knee arthroplastv and was predictive of postoperative morphine consumption PMID:17717244

  3. Intrathecal cannabinoid-1 receptor agonist prevents referred hyperalgesia in acute acrolein-induced cystitis in rats

    PubMed Central

    Jones, Marsha Ritter; Wang, Zun-Yi; Bjorling, Dale E

    2015-01-01

    We investigated the capacity of intrathecal arachidonyl-2’-chloroethylamide (ACEA), a cannabinoid-1 receptor (CB1R) agonist, to inhibit referred hyperalgesia and increased bladder contractility resulting from acute acrolein-induced cystitis in rats. 24 female rats were divided into 4 groups: 1) intrathecal vehicle/intravesical saline; 2) intrathecal vehicle/intravesical acrolein; 3) intrathecal ACEA/intravesical saline; and 4) intrathecal ACEA/intravesical acrolein. Bladder catheters were placed 4-6 days prior to the experiment. On the day of the experiment, rats were briefly anesthetized with isoflurane to recover the external end of the cystostomy catheter. After recovery from anesthesia, pre-treatment cystometry was performed, and mechanical sensitivity of the hindpaws was determined. Rats were again briefly anesthetized with isoflurane to inject ACEA or vehicle into the intrathecal space between L5-L6. Beginning 10 minutes after intrathecal injection, saline or acrolein was infused into the bladder for 30 minutes. Post-treatment cystometry and mechanical sensitivity testing were performed. Rats were euthanized, and bladders were collected, weighed, and fixed for histology. The intrathecal vehicle/intravesical acrolein group developed mechanical hyperalgesia with post-treatment mechanical sensitivity of 6 ± 0.3 g compared to pretreatment of 14 ± 0.4 g (p < 0.01). Pre- and post-treatment hind paw mechanical sensitivity was statistically similar in rats that received intrathecal ACEA prior to intravesical infusion of acrolein (15 ± 0.2 g and 14 ± 0.4 g, respectively). Acrolein treatment increased basal bladder pressure and maximal voiding pressure and decreased intercontraction interval and voided volume. However, intrathecal ACEA was ineffective in improving acrolein-related urodynamic changes. In addition, bladder histology demonstrated submucosal and muscularis edema that was similar for all acrolein-treated groups, irrespective of ACEA treatment

  4. A possible mechanism in DHEA-mediated protection against osteoarthritis.

    PubMed

    Li, Wei-Jun; Tang, Lu-Ping; Xiong, Yan; Chen, Wei-Ping; Zhou, Xin-Die; Ding, Qian-Hai; Wu, Li-Dong

    2014-11-01

    Dehydroepiandrosterone (DHEA) and its ester form, DHEA-S, are the most abundant steroids in human plasma. Our previous studies showed that DHEA protects against osteoarthritis (OA). The aim of this paper was to explore the possible mechanisms that underlie DHEA-mediated protection against OA. We tested the expression of β-catenin, it was increased significantly in OA. Rabbit cartilage was treated with various concentrations of DHEA in both IL-1β-induced rabbit chondrocytes and in rabbit cartilage from the anterior cruciate ligament transaction-induced OA model. We found DHEA decreased the expression of β-catenin. Then we further activated Wnt/β-catenin signaling by β-catenin transfection and inactivated it by the inhibitor Dickkopf1 in chondrocytes to reveal its role in the pathogenesis of OA. It turns out the protective effect of DHEA was significantly decreased when Wnt/β-catenin signaling was activated, while inactivating Wnt/β-catenin signaling enhanced the effects of DHEA. Therefore, we hypothesize that DHEA probably exerted its chondroprotective effect by regulating Wnt/β-catenin signaling. Our findings demonstrate the critical role of Wnt/β-catenin signaling in DHEA-mediated protection against OA. PMID:25065588

  5. Mechanical Forces Mediate Localized Topological Change in Epithelia

    PubMed Central

    Li, Yingzi; Naveed, Hammad; Kachalo, Sema; Xu, Lisa X.; Liang, Jie

    2013-01-01

    Regulation of cell growth and proliferation has a fundamental role in tissue development, organogenesis, and disease progression. Conserved distribution of the number of sides of cells with a mean value of six was found in a variety of proliferating epithelia. Previous studies have shown that clones of proliferating cells bounded by quiescent cells have fewer sides than normal epithelia. However, the mechanisms for mediating such localized topological change remain poorly understood. In this study, we use a two-dimensional vertex model with consideration of mechanical forces to investigate how differential proliferation and forces can influence cell shape and tissue morphogenesis, and how they may lead to distorted topological change. We find that differential proliferation alone is insufficient to affect the topology of boundary proliferating cells. Rather, increased surface tension on the boundary, in addition to differential proliferation, can significantly decrease the average number of cell sides. Our results are consistent with experimental observations. We conclude that mechanical forces in addition to localized differential proliferation are required to produce the distorted topological change which significantly impacts the overall cell shape and tissue morphogenesis. PMID:22254279

  6. Mechanisms of Defense against Intracellular Pathogens Mediated by Human Macrophages.

    PubMed

    Bloom, Barry R; Modlin, Robert L

    2016-06-01

    The key question our work has sought to address has been, "What are the necessary and sufficient conditions that engender protection from intracellular pathogens in the human host?" The origins of this work derive from a long-standing interest in the mechanisms of protection against two such paradigmatic intracellular pathogens, Mycobacterium tuberculosis and Mycobacterium leprae, that have brilliantly adapted to the human host. It was obvious that these pathogens, which cause chronic diseases and persist in macrophages, must have acquired subtle strategies to resist host microbicidal mechanisms, yet since the vast majority of individuals infected with M. tuberculosis do not develop disease, there must be some potent human antimicrobial mechanisms. What follows is not a comprehensive review of the vast literature on the role of human macrophages in protection against infectious disease, but a summary of the research in our two laboratories with collaborators that we hope has contributed to some understanding of mechanisms of resistance and pathogenesis. While mouse models revealed some necessary conditions for protection, e.g., innate immunity, Th1 cells and their cytokines, and major histocompatibility complex class I-restricted T cells, here we emphasize multiple antimicrobial mechanisms that exist in human macrophages that differ from those of most experimental animals. Prominent here is the vitamin D-dependent antimicrobial pathway common to human macrophages activated by innate and acquired immune responses, mediated by antimicrobial peptides, e.g., cathelicidin, through an interleukin-15- and interleukin-32-dependent common pathway that is necessary for macrophage killing of M. tuberculosis in vitro. PMID:27337485

  7. Role of peripheral and spinal 5-HT(3) receptors in development and maintenance of formalin-induced long-term secondary allodynia and hyperalgesia.

    PubMed

    Bravo-Hernández, Mariana; Cervantes-Durán, Claudia; Pineda-Farias, Jorge Baruch; Barragán-Iglesias, Paulino; López-Sánchez, Pedro; Granados-Soto, Vinicio

    2012-04-01

    The role of peripheral and spinal 5-HT(3) receptors in formalin-induced secondary allodynia and hyperalgesia in rats was assessed. Formalin produced acute nociceptive behaviors (flinching and licking/lifting) followed by long-term secondary mechanical allodynia and hyperalgesia in both paws. In experiments where the test drug was anticipated to augment or antagonize the response, 0.5 or 1% formalin, respectively, was used for injection. Peripheral ipsilateral, but not contralateral, pre-treatment (-10 min) with serotonin (5-HT, 10-100 nmol/paw) and the selective 5-HT(3) receptor agonist 1-(m-chlorophenyl)-biguanide (m-CPBG, 10-300 nmol/paw) increased 0.5% formalin-induced secondary allodynia and hyperalgesia in both paws. Moreover, spinal pre-treatment with m-CPBG (10-300 nmol/rat) increased 0.5% formalin-induced secondary hyperalgesia but not allodynia in both paws. Accordingly, peripheral ipsilateral (30-300 nmol/paw), but not contralateral (300 nmol/paw), and spinal (10-100 nmol) pre-treatment with the selective 5-HT(3) receptor antagonist ondansetron prevented 1% formalin-induced secondary mechanical allodynia and hyperalgesia in both paws. The peripheral pronociceptive effects of 5-HT (100 nmol/paw) and m-CPBG (300 nmol/paw) as well as the spinal effect of m-CPBG (300 nmol/rat) were completely prevented by the peripheral (10 nmol/paw) and spinal (1 nmol/rat) injection, respectively, of ondansetron. At these doses, ondansetron did not modify per se formalin-induced nociceptive behaviors. Spinal (30-300 nmol/rat), but not peripheral (300 nmol/paw), post-treatment (on day 6) with ondansetron reversed established formalin-induced secondary mechanical allodynia and hyperalgesia in both paws. Results suggest that a barrage of afferent input induced by 5-HT at peripheral 5-HT(3) receptors participates in the development of formalin-induced long-term secondary allodynia and hyperalgesia in the rat. In addition, our data suggest that spinal 5-HT(3) receptors play an

  8. Pathophysiological mechanisms of catecholamine and cocaine-mediated cardiotoxicity.

    PubMed

    Liaudet, Lucas; Calderari, Belinda; Pacher, Pal

    2014-11-01

    Overactivation of the sympatho-adrenergic system is an essential mechanism providing short-term adaptation to the stressful conditions of critical illnesses. In the same way, the administration of exogenous catecholamines is mandatory to support the failing circulation in acutely ill patients. In contrast to these short-term benefits, prolonged adrenergic stress is detrimental to the cardiovascular system by initiating a series of adverse effects triggering significant cardiotoxicity, whose pathophysiological mechanisms are complex and only partially elucidated. In addition to the development of myocardial oxygen supply/demand imbalance induced by the sustained activation of adrenergic receptors, catecholamines can damage cardiomyocytes by fostering mitochondrial dysfunction, via two main mechanisms. The first one is calcium overload, consecutive to β-adrenergic receptor-mediated activation of protein kinase A and subsequent phosphorylation of multiple Ca(2+)-cycling proteins. The second one is oxidative stress, primarily related to the transformation of catecholamines into "aminochromes," which undergo redox cycling in mitochondria to generate copious amounts of oxygen-derived free radicals. In turn, calcium overload and oxidative stress promote mitochondrial permeability transition and cardiomyocyte cell death, both via the apoptotic and necrotic pathways. Comparable mechanisms of myocardial toxicity, including marked oxidative stress and mitochondrial dysfunction, have been reported with the use of cocaine, a common recreational drug with potent sympathomimetic activity. The aim of the current review is to present in detail the pathophysiological processes underlying the development of catecholamine and cocaine-induced cardiomyopathy, as such conditions may be frequently encountered in the clinical practice of cardiologists and ICU specialists. PMID:24398587

  9. Identifying immune mechanisms mediating the hypertension during preeclampsia.

    PubMed

    LaMarca, Babbette; Cornelius, Denise C; Harmon, Ashlyn C; Amaral, Lorena M; Cunningham, Mark W; Faulkner, Jessica L; Wallace, Kedra

    2016-07-01

    Preeclampsia (PE) is a pregnancy-associated disorder that affects 5-8% of pregnancies and is a major cause of maternal, fetal, and neonatal morbidity and mortality. Hallmark characteristics of PE are new onset hypertension after 20 wk gestation with or without proteinuria, chronic immune activation, fetal growth restriction, and maternal endothelial dysfunction. However, the pathophysiological mechanisms that lead to the development of PE are poorly understood. Recent data from studies of both clinical and animal models demonstrate an imbalance in the subpopulations of CD4+ T cells and a role for these cells as mediators of inflammation and hypertension during pregnancy. Specifically, it has been proposed that the imbalance between two CD4+ T cell subtypes, regulatory T cells (Tregs) and T-helper 17 cells (Th17s), is involved in the pathophysiology of PE. Studies from our laboratory highlighting how this imbalance contributes to vasoactive factors, endothelial dysfunction, and hypertension during pregnancy will be discussed in this review. Therefore, the purpose of this review is to highlight hypertensive mechanisms stimulated by inflammatory factors in response to placental ischemia, thereby elucidating a role. PMID:27097659

  10. Mechanisms of gold nanoparticle mediated ultrashort laser cell membrane perforation

    NASA Astrophysics Data System (ADS)

    Schomaker, M.; Baumgart, J.; Motekaitis, D.; Heinemann, D.; Krawinkel, J.; Pangalos, M.; Bintig, W.; Boulais, E.; Lachaine, R.; St.-Louis Lalonde, B.; Ngezahayo, A.; Meunier, M.; Heisterkamp, A.

    2011-03-01

    The gold nanoparticle (AuNP) mediated ultrashort laser cell membrane perforation has been proven as an efficient delivery method to bring membrane impermeable molecules into the cytoplasm. Nevertheless, the underlying mechanisms have not been fully determined yet. Different effects may occur when irradiating a AuNP with ultrashort laser pulses and finally enable the molecule to transfer. Depending on the parameters (pulse length, laser fluence and wavelength, particle size and shape, etc.) light absorption or an enhanced near field scattering can lead to perforation of the cell membrane when the particle is in close vicinity. Here we present our experimental results to clarify the perforation initiating mechanisms. The generation of cavitation and gas bubbles due to the laser induced effects were observed via time resolved imaging. Additionally, pump-probe experiments for bubble detection was performed. Furthermore, in our patch clamp studies a depolarization of the membrane potential and the current through the membrane of AuNP loaded cell during laser treatment was detected. This indicates an exchange of extra- and intra cellular ions trough the perforated cell membrane for some milliseconds. Additionally investigations by ESEM imaging were applied to study the interaction of cells and AuNP after co incubation. The images show an attachment of AuNP at the cell membrane after several hours of incubation. Moreover, images of irradiated and AuNP loaded cells were taken to visualize the laser induced effects.

  11. Temporal Visual Mechanisms May Mediate Compensation for Macular Pigment.

    PubMed

    Stringham, Nicole T; Stringham, James M

    2015-12-01

    Macular pigment (MP) is a pre-receptoral filter that is diet derived and deposited in relatively high optical density in the foveal region of the retina. Due to its yellow coloration, MP absorbs light of relatively short wavelengths, ranging from 400 nm to 520 nm. Despite the spectral and spatial nonuniformity imposed upon the sensory retina by MP, perception appears to be relatively uniform across the central visual field. MP therefore offers an opportunity to determine experimentally potential mechanisms responsible for mediating this uniformity. After assessing, in 14 subjects, MP's effects on the temporal sensitivity of both the short-wavelength- and middle-/long-wavelength-sensitive visual pathways, it appears that the visual system compensates for absorption of short-wavelength light by MP by slowing the sampling rate of short-wavelength cones and by increasing the processing speed of middle-/long-wavelength-sensitive cones. This mechanism could work via temporal summation or a temporal neural code, whereby slower response dynamics lead to amplification of relatively weak signals. PMID:26562864

  12. Intracolonical administration of protease-activated receptor-2 agonists produced visceral hyperalgesia by up-regulating serotonin in the colon of rats.

    PubMed

    Li, Zhi; Zhang, Xiao-Jun; Xu, Hong-xi; Sung, Joseph J Y; Bian, Zhao-xiang

    2009-03-15

    This study aimed to investigate the underlying mechanism of protease-activated receptor-2 (PAR-2) agonist-induced visceral hyperalgesia. Male Sprague-Dawley rat pups were submitted to colonic injection of PAR-2 agonist for 6 consecutive days. The visceral sensitivity to colorectal distention was evaluated by electromyography. The enterochromaffin (EC) cell number, 5-HT content and tryrptophan hydroxylase (TPH) protein expression were detected with immunohistochemistry, fluorescent measurement and Western blot analysis. PAR-2 agonist induced a significant increase of visceral nociceptive response to colorectal distention and a series of neurochemical changes in rat colon, including proliferation of EC cells, increased 5-HT content and enhanced TPH expression. Expression of PAR-2 in EC cells was reported for the first time. Further, selective 5-HT(3) receptor antagonist alosteron significantly inhibited PAR-2-induced visceral hyperalgesia. The enhanced 5-HT signaling is likely responsible for the visceral hyperalgesia induced by PAR-2 agonist. Interruption of this pathway is a possible target for the treatment of visceral hyperalgesia in gastrointestinal diseases. PMID:19374846

  13. Dual pH-Mediated Mechanized Hollow Zirconia Nanospheres.

    PubMed

    Wang, MingDong; Gong, GuangCai; Feng, Jing; Wang, Ting; Ding, ChenDi; Zhou, BaoJing; Jiang, Wei; Fu, JiaJun

    2016-09-01

    We demonstrate for the first time how to assemble mechanized hollow zirconia nanospheres (MHzNs), consisting of hollow mesoporous zirconia nanospheres (HMZNs) as nanoscaffolds and supramolecular switches anchored on the exterior surface of HMZNs. The remarkable advantage of substitution of HMZNs for conventional mesoporous silica nanoscaffolds is that HMZNs can suffer the hot alkaline reaction environment, which provides a novel strategy for functionalization and thus achieve dual pH-mediated controlled release functions by simple and practicable assembly procedure. Under neutral solution, cucurbituril[7] (CB[7]) macrocycles complexed with propanone bis(2-aminoethyl)ketal (PBAEK) to form [2]pseudorotaxanes as supramolecular switches, blocking the pore orifices and preventing the undesirable leakage of cargoes. When solution pH was adjusted to alkaline range, CB[7] macrocycles, acting as caps, disassociated from PBAEK stalks and opened the switches due to the dramatic decrease of ion-dipole interactions. While under acidic conditions, PBAEK stalks were broken on account of the cleavage of ketal groups, resulting in the collapse of supramolecular switches and subsequent release of encapsulated cargoes. MHzNs owning dual pH-mediated controlled release characteristic are expected to apply in many fields. In this work, the feasibility of doxorubicin (DOX)-loaded MHzNs as targeted drug delivery systems was evaluated. In vitro cellular studies demonstrate that DOX-loaded MHzNs can be easily taken up by SMMC-7721 cells, can rapidly release DOX intracellularly, and can enhance cytotoxicity against tumor cells, proving their potential for chemotherapy. PMID:27523904

  14. Selective targeting of ASIC3 using artificial miRNAs inhibits primary and secondary hyperalgesia after muscle inflammation

    PubMed Central

    Walder, Roxanne Y.; Gautam, Mamta; Wilson, Steven P.; Benson, Christopher J.; Sluka, Kathleen A.

    2012-01-01

    Acid-sensing ion channels (ASICs) are activated by acidic pH and may play a significant role in the development of hyperalgesia. Earlier studies show ASIC3 is important for induction of hyperalgesia after muscle insult using ASIC3−/− mice. ASIC3−/− mice lack ASIC3 throughout the body, and the distribution and composition of ASICs could be different from wild-type mice. We therefore tested whether knockdown of ASIC3 in primary afferents innervating muscle of adult wild-type mice prevented development of hyper-algesia to muscle inflammation. We cloned and characterized artificial miRNAs (miR-ASIC3) directed against mouse ASIC3 (mASIC3) to downregulate ASIC3 expression in vitro and in vivo. In CHO-K1 cells transfected with mASIC3 cDNA in culture, the miR-ASIC3 constructs inhibited protein expression of mASIC3 and acidic pH-evoked currents and had no effect on protein expression or acidic pH-evoked currents of ASIC1a. When miR-ASIC3 was used in vivo, delivered into the muscle of mice using a herpes simplex viral vector, both muscle and paw mechanical hyperalgesia were reduced after carrageenan-induced muscle inflammation. ASIC3 mRNA in DRG and protein levels in muscle were decreased in vivo by miRASIC3. In CHO-K1 cells co-transfected with ASIC1a and ASIC3, miR-ASIC3 reduced the amplitude of acidic pH-evoked currents, suggesting an overall inhibition in the surface expression of heteromeric ASIC3-containing channels. Our results show, for the first time, that reducing ASIC3 in vivo in primary afferent fibers innervating muscle prevents the development of inflammatory hyperalgesia in wild-type mice, and thus, may have applications in the treatment of musculoskeletal pain in humans. PMID:21843914

  15. TRPV1 function is modulated by Cdk5-mediated phosphorylation: insights into the molecular mechanism of nociception

    PubMed Central

    Jendryke, Thomas; Prochazkova, Michaela; Hall, Bradford E.; Nordmann, Grégory C.; Schladt, Moritz; Milenkovic, Vladimir M.; Kulkarni, Ashok B.; Wetzel, Christian H.

    2016-01-01

    TRPV1 is a polymodally activated cation channel acting as key receptor in nociceptive neurons. Its function is strongly affected by kinase-mediated phosphorylation leading to hyperalgesia and allodynia. We present behavioral and molecular data indicating that TRPV1 is strongly modulated by Cdk5-mediated phosphorylation at position threonine-407(mouse)/T406(rat). Increasing or decreasing Cdk5 activity in genetically engineered mice has severe consequences on TRPV1-mediated pain perception leading to altered capsaicin consumption and sensitivity to heat. To understand the molecular and structural/functional consequences of TRPV1 phosphorylation, we generated various rTRPV1T406 receptor variants to mimic phosphorylated or dephosphorylated receptor protein. We performed detailed functional characterization by means of electrophysiological whole-cell and single-channel recordings as well as Ca2+-imaging and challenged recombinant rTRPV1 receptors with capsaicin, low pH, or heat. We found that position T406 is critical for the function of TRPV1 by modulating ligand-sensitivity, activation, and desensitization kinetics as well as voltage-dependence. Based on high resolution structures of TRPV1, we discuss T406 being involved in the molecular transition pathway, its phosphorylation leading to a conformational change and influencing the gating of the receptor. Cdk5-mediated phosphorylation of T406 can be regarded as an important molecular switch modulating TRPV1-related behavior and pain sensitivity. PMID:26902776

  16. TRPV1 function is modulated by Cdk5-mediated phosphorylation: insights into the molecular mechanism of nociception.

    PubMed

    Jendryke, Thomas; Prochazkova, Michaela; Hall, Bradford E; Nordmann, Grégory C; Schladt, Moritz; Milenkovic, Vladimir M; Kulkarni, Ashok B; Wetzel, Christian H

    2016-01-01

    TRPV1 is a polymodally activated cation channel acting as key receptor in nociceptive neurons. Its function is strongly affected by kinase-mediated phosphorylation leading to hyperalgesia and allodynia. We present behavioral and molecular data indicating that TRPV1 is strongly modulated by Cdk5-mediated phosphorylation at position threonine-407(mouse)/T406(rat). Increasing or decreasing Cdk5 activity in genetically engineered mice has severe consequences on TRPV1-mediated pain perception leading to altered capsaicin consumption and sensitivity to heat. To understand the molecular and structural/functional consequences of TRPV1 phosphorylation, we generated various rTRPV1T406 receptor variants to mimic phosphorylated or dephosphorylated receptor protein. We performed detailed functional characterization by means of electrophysiological whole-cell and single-channel recordings as well as Ca(2+)-imaging and challenged recombinant rTRPV1 receptors with capsaicin, low pH, or heat. We found that position T406 is critical for the function of TRPV1 by modulating ligand-sensitivity, activation, and desensitization kinetics as well as voltage-dependence. Based on high resolution structures of TRPV1, we discuss T406 being involved in the molecular transition pathway, its phosphorylation leading to a conformational change and influencing the gating of the receptor. Cdk5-mediated phosphorylation of T406 can be regarded as an important molecular switch modulating TRPV1-related behavior and pain sensitivity. PMID:26902776

  17. Molecular mechanism of statin-mediated LOX-1 inhibition.

    PubMed

    Biocca, Silvia; Iacovelli, Federico; Matarazzo, Sara; Vindigni, Giulia; Oteri, Francesco; Desideri, Alessandro; Falconi, Mattia

    2015-01-01

    Statins are largely used in clinics in the treatment of patients with cardiovascular diseases for their effect on lowering circulating cholesterol. Lectin-like oxidized low-density lipoprotein (LOX-1), the primary receptor for ox-LDL, plays a central role in the pathogenesis of atherosclerosis and cardiovascular disorders. We have recently shown that chronic exposure of cells to lovastatin disrupts LOX-1 receptor cluster distribution in plasma membranes, leading to a marked loss of LOX-1 function. Here we investigated the molecular mechanism of statin-mediated LOX-1 inhibition and we demonstrate that all tested statins are able to displace the binding of fluorescent ox-LDL to LOX-1 by a direct interaction with LOX-1 receptors in a cell-based binding assay. Molecular docking simulations confirm the interaction and indicate that statins completely fill the hydrophobic tunnel that crosses the C-type lectin-like (CTLD) recognition domain of LOX-1. Classical molecular dynamics simulation technique applied to the LOX-1 CTLD, considered in the entire receptor structure with or without a statin ligand inside the tunnel, indicates that the presence of a ligand largely increases the dimer stability. Electrophoretic separation and western blot confirm that different statins binding stabilize the dimer assembly of LOX-1 receptors in vivo. The simulative and experimental results allow us to propose a CTLD clamp motion, which enables the receptor-substrate coupling. These findings reveal a novel and significant functional effect of statins. PMID:25950192

  18. Molecular mechanism of statin-mediated LOX-1 inhibition

    PubMed Central

    Biocca, Silvia; Iacovelli, Federico; Matarazzo, Sara; Vindigni, Giulia; Oteri, Francesco; Desideri, Alessandro; Falconi, Mattia

    2015-01-01

    Statins are largely used in clinics in the treatment of patients with cardiovascular diseases for their effect on lowering circulating cholesterol. Lectin-like oxidized low-density lipoprotein (LOX-1), the primary receptor for ox-LDL, plays a central role in the pathogenesis of atherosclerosis and cardiovascular disorders. We have recently shown that chronic exposure of cells to lovastatin disrupts LOX-1 receptor cluster distribution in plasma membranes, leading to a marked loss of LOX-1 function. Here we investigated the molecular mechanism of statin-mediated LOX-1 inhibition and we demonstrate that all tested statins are able to displace the binding of fluorescent ox-LDL to LOX-1 by a direct interaction with LOX-1 receptors in a cell-based binding assay. Molecular docking simulations confirm the interaction and indicate that statins completely fill the hydrophobic tunnel that crosses the C-type lectin-like (CTLD) recognition domain of LOX-1. Classical molecular dynamics simulation technique applied to the LOX-1 CTLD, considered in the entire receptor structure with or without a statin ligand inside the tunnel, indicates that the presence of a ligand largely increases the dimer stability. Electrophoretic separation and western blot confirm that different statins binding stabilize the dimer assembly of LOX-1 receptors in vivo. The simulative and experimental results allow us to propose a CTLD clamp motion, which enables the receptor-substrate coupling. These findings reveal a novel and significant functional effect of statins. PMID:25950192

  19. Circadian rhythm of mechanically mediated differentiation of osteoblasts.

    PubMed

    Roberts, W E; Klingler, E; Mozsary, P G

    1984-01-01

    Rats entrained to alternating 12 h light/dark periods were sacrificed at hourly intervals over one complete circadian cycle. Each animal was injected with 3H-Thymidine 1 h before death. Autoradiographs of serial sections of maxillary first molar periodontal ligament (PDL) were prepared. Nuclear volume was determined for labeled fibroblastlike PDL cells along a physiological bone forming surface. Preosteoblasts (large nuclei), the immediate proliferating precursors of osteoblasts, were found to synthesize DNA primarily during the environmental light period and divide during the subsequent dark cycle. Less differentiated precursor cells (small nuclei), the proliferating predecessors of preosteoblasts, were in S phase primarily during the dark period and divided in the following light cycle. Since previous studies have indicated, the stress/strain-mediated increase in nuclear size to form preosteoblasts also requires about 8-12 h, the least complex osteoblast differentiation model, which is consistent with the present data, is a 60 h sequence involving at least four cell types and five alternating dark/light cycles. The principal rate-limiting step in osteoblast differentiation is the mechanically related shift in nuclear size (change in genomic expression) associated with formation of preosteoblasts. PMID:6430524

  20. Complications of sodium hydroxide chemical matrixectomy: nail dystrophy, allodynia, hyperalgesia.

    PubMed

    Bostancı, Seher; Koçyiğit, Pelin; Güngör, Hilayda Karakök; Parlak, Nehir

    2014-11-01

    Ingrown toenails are seen most commonly in young adults, and they can seriously affect daily life. Partial nail avulsion with chemical matrixectomy, generally by using either sodium hydroxide or phenol, is one of the most effective treatment methods. Known complications of phenol matrixectomy are unpredictable tissue damage, prolonged postoperative drainage, increased secondary infection rates, periostitis, and poor cosmetic results. To our knowledge, there have been no reports about the complications related to sodium hydroxide matrixectomy. Herein, we describe three patients who developed nail dystrophy, allodynia, and hyperalgesia after sodium hydroxide matrixectomy. PMID:25514278

  1. Vitamin B complex attenuated heat hyperalgesia following infraorbital nerve constriction in rats and reduced capsaicin in vivo and in vitro effects.

    PubMed

    Kopruszinski, Caroline M; Reis, Renata C; Bressan, Elisangela; Reeh, Peter W; Chichorro, Juliana G

    2015-09-01

    Vitamins of the B complex attenuate some neuropathic pain sensory aspects in various animal models and in patients, but the mechanisms underlying their effects remain to be elucidated. Herein it was investigated if the treatment with a vitamin B complex (VBC) reduces heat hyperalgesia in rats submitted to infraorbital nerve constriction and the possibility that TRPV1 receptors represent a target for B vitamins. In the present study, the VBC refers to a combination of vitamins B1, B6 and B12 at low- (18, 18 and 1.8mg/kg, respectively) or high- (180, 180 and 18mg/kg, respectively) doses. Acute treatment of rats with either the low- or the high-doses combination reduced heat hyperalgesia after nerve injury, but the high-doses combination resulted in a long-lasting effect. Repeated treatment with the low-dose combination reduced heat hyperalgesia on day four after nerve injury and showed a synergist effect with a single injection of carbamazepine (3 or 10mg/kg), which per se failed to modify the heat threshold. In naïve rats, acute treatment with the high-dose of VBC or B1 and B12 vitamins independently reduced heat hyperalgesia evoked by capsaicin (3µg into the upper lip). Moreover, the VBC, as well as, each one of the B vitamins independently reduced the capsaicin-induced calcium responses in HEK 293 cells transiently transfected with the human TRPV1 channels. Altogether, these results indicate that B vitamins can be useful to control heat hyperalgesia associated with trigeminal neuropathic pain and that modulation of TRPV1 receptors may contribute to their anti-hyperalgesic effects. PMID:26048309

  2. Mechanical signals promote osteogenic fate through a primary cilia-mediated mechanism.

    PubMed

    Chen, Julia C; Hoey, David A; Chua, Mardonn; Bellon, Raymond; Jacobs, Christopher R

    2016-04-01

    It has long been suspected, but never directly shown, that bone formed to accommodate an increase in mechanical loading is related to the creation of osteoblasts from skeletal stem cells. Indeed, biophysical stimuli potently regulate osteogenic lineage commitmentin vitro In this study, we transplanted bone marrow cells expressing green fluorescent protein, to enable lineage tracing, and subjected mice to a biophysical stimulus, to elicit a bone-forming response. We detected cells derived from transplanted progenitors embedded within the bone matrix near active bone-forming surfaces in response to loading, demonstrating for the first time, that mechanical signals enhance the homing and attachment of bone marrow cells to bone surfaces and the commitment to an osteogenic lineage of these cellsin vivo Furthermore, we used an inducible Cre/Lox recombination system to delete kinesin family member 3A (Kif3a), a gene that is essential for primary cilia formation, at will in transplanted cells and their progeny, regardless of which tissue may have incorporated them. Disruption of the mechanosensing organelle, the primary cilium in a progenitor population, significantly decreased the amount of bone formed in response to mechanical stimulation. The collective results of our study directly demonstrate that, in a novel experimental stem cell mechanobiology model, mechanical signals enhance osteogenic lineage commitmentin vivoand that the primary cilium contributes to this process.-Chen, J. C., Hoey, D. A., Chua, M., Bellon, R., Jacobs, C. R. Mechanical signals promote osteogenic fate through a primary cilia-mediated mechanism. PMID:26675708

  3. Effect of painless diabetic neuropathy on pressure pain hypersensitivity (hyperalgesia) after acute foot trauma

    PubMed Central

    Wienemann, Tobias; Chantelau, Ernst A.; Koller, Armin

    2014-01-01

    Introduction and objective Acute injury transiently lowers local mechanical pain thresholds at a limb. To elucidate the impact of painless (diabetic) neuropathy on this post-traumatic hyperalgesia, pressure pain perception thresholds after a skeletal foot trauma were studied in consecutive persons without and with neuropathy (i.e. history of foot ulcer or Charcot arthropathy). Design and methods A case–control study was done on 25 unselected clinical routine patients with acute unilateral foot trauma (cases: elective bone surgery; controls: sprain, toe fracture). Cases were 12 patients (11 diabetic subjects) with severe painless neuropathy and chronic foot pathology. Controls were 13 non-neuropathic persons. Over 1 week after the trauma, cutaneous pressure pain perception threshold (CPPPT) and deep pressure pain perception threshold (DPPPT) were measured repeatedly, adjacent to the injury and at the opposite foot (pinprick stimulators, Algometer II®). Results In the control group, post-traumatic DPPPT (but not CPPPT) at the injured foot was reduced by about 15–25%. In the case group, pre- and post-operative CPPPT and DPPPT were supranormal. Although DPPPT fell post-operatively by about 15–20%, it remained always higher than the post-traumatic DPPPT in the control group: over musculus abductor hallucis 615 kPa (kilopascal) versus 422 kPa, and over metatarsophalangeal joint 518 kPa versus 375 kPa (medians; case vs. control group); CPPPT did not decrease post-operatively. Conclusion Physiological nociception and post-traumatic hyperalgesia to pressure are diminished at the foot with severe painless (diabetic) neuropathy. A degree of post-traumatic hypersensitivity required to ‘pull away’ from any one, even innocuous, mechanical impact in order to avoid additional damage is, therefore, lacking. PMID:25397867

  4. Diffuse traumatic brain injury induces prolonged immune dysregulation and potentiates hyperalgesia following a peripheral immune challenge

    PubMed Central

    Rowe, Rachel K; Ellis, Gavin I; Harrison, Jordan L; Bachstetter, Adam D; Corder, Gregory F; Van Eldik, Linda J; Taylor, Bradley K; Marti, Francesc

    2016-01-01

    Background Nociceptive and neuropathic pain occurs as part of the disease process after traumatic brain injury (TBI) in humans. Central and peripheral inflammation, a major secondary injury process initiated by the traumatic brain injury event, has been implicated in the potentiation of peripheral nociceptive pain. We hypothesized that the inflammatory response to diffuse traumatic brain injury potentiates persistent pain through prolonged immune dysregulation. Results To test this, adult, male C57BL/6 mice were subjected to midline fluid percussion brain injury or to sham procedure. One cohort of mice was analyzed for inflammation-related cytokine levels in cortical biopsies and serum along an acute time course. In a second cohort, peripheral inflammation was induced seven days after surgery/injury with an intraplantar injection of carrageenan. This was followed by measurement of mechanical hyperalgesia, glial fibrillary acidic protein and Iba1 immunohistochemical analysis of neuroinflammation in the brain, and flow cytometric analysis of T-cell differentiation in mucosal lymph. Traumatic brain injury increased interleukin-6 and chemokine ligand 1 levels in the cortex and serum that peaked within 1–9 h and then resolved. Intraplantar carrageenan produced mechanical hyperalgesia that was potentiated by traumatic brain injury. Further, mucosal T cells from brain-injured mice showed a distinct deficiency in the ability to differentiate into inflammation-suppressing regulatory T cells (Tregs). Conclusions We conclude that traumatic brain injury increased the inflammatory pain associated with cutaneous inflammation by contributing to systemic immune dysregulation. Regulatory T cells are immune suppressors and failure of T cells to differentiate into regulatory T cells leads to unregulated cytokine production which may contribute to the potentiation of peripheral pain through the excitation of peripheral sensory neurons. In addition, regulatory T cells are

  5. GABAergic transmission in rat pontine reticular formation regulates the induction phase of anesthesia and modulates hyperalgesia caused by sleep deprivation.

    PubMed

    Vanini, Giancarlo; Nemanis, Kriste; Baghdoyan, Helen A; Lydic, Ralph

    2014-07-01

    The oral part of the pontine reticular formation (PnO) contributes to the regulation of sleep, anesthesia and pain. The role of PnO γ-aminobutyric acid (GABA) in modulating these states remains incompletely understood. The present study used time to loss and time to resumption of righting response (LoRR and RoRR) as surrogate measures of loss and resumption of consciousness. This study tested three hypotheses: (i) pharmacologically manipulating GABA levels in rat PnO alters LoRR, RoRR and nociception; (ii) propofol decreases GABA levels in the PnO; and (iii) inhibiting GABA synthesis in the PnO blocks hyperalgesia caused by sleep deprivation. Administering a GABA synthesis inhibitor [3-mercaptopropionic acid (3-MPA)] or a GABA uptake inhibitor [nipecotic acid (NPA)] into rat PnO significantly altered LoRR caused by propofol. 3-MPA significantly decreased LoRR for propofol (-18%). NPA significantly increased LoRR during administration of propofol (36%). Neither 3-MPA nor NPA altered RoRR following cessation of propofol or isoflurane delivery. The finding that LoRR was decreased by 3-MPA and increased by NPA is consistent with measures showing that extracellular GABA levels in the PnO were decreased (41%) by propofol. Thermal nociception was significantly decreased by 3-MPA and increased by NPA, and 3-MPA blocked the hyperalgesia caused by sleep deprivation. The results demonstrate that GABA levels in the PnO regulate the time for loss of consciousness caused by propofol, extend the concept that anesthetic induction and emergence are not inverse processes, and suggest that GABAergic transmission in the PnO mediates hyperalgesia caused by sleep loss. PMID:24674578

  6. δ-Opioid receptor agonists inhibit migraine-related hyperalgesia, aversive state and cortical spreading depression in mice

    PubMed Central

    Pradhan, Amynah A; Smith, Monique L; Zyuzin, Jekaterina; Charles, Andrew

    2014-01-01

    Background and Purpose Migraine is an extraordinarily common brain disorder for which treatment options continue to be limited. Agonists that activate the δ-opioid receptor may be promising for the treatment of migraine as they are highly effective for the treatment of chronic rather than acute pain, do not induce hyperalgesia, have low abuse potential and have anxiolytic and antidepressant properties. The aim of this study was to investigate the therapeutic potential of δ-opioid receptor agonists for migraine by characterizing their effects in mouse migraine models. Experimental Approach Mechanical hypersensitivity was assessed in mice treated with acute and chronic doses of nitroglycerin (NTG), a known human migraine trigger. Conditioned place aversion to NTG was also measured as a model of migraine-associated negative affect. In addition, we assessed evoked cortical spreading depression (CSD), an established model of migraine aura, in a thinned skull preparation. Key Results NTG evoked acute and chronic mechanical and thermal hyperalgesia in mice, as well as conditioned place aversion. Three different δ-opioid receptor agonists, SNC80, ARM390 and JNJ20788560, significantly reduced NTG-evoked hyperalgesia. SNC80 also abolished NTG-induced conditioned place aversion, suggesting that δ-opioid receptor activation may also alleviate the negative emotional state associated with migraine. We also found that SNC80 significantly attenuated CSD, a model that is considered predictive of migraine preventive therapies. Conclusions and Implications These data show that δ-opioid receptor agonists modulate multiple basic mechanisms associated with migraine, indicating that δ-opioid receptors are a promising therapeutic target for this disorder. PMID:24467301

  7. Irritable bowel syndrome: a test of the colonic hyperalgesia hypothesis.

    PubMed

    Latimer, P; Campbell, D; Latimer, M; Sarna, S; Daniel, E; Waterfall, W

    1979-09-01

    This study tested the hypothesis that, patients with irritable bowel syndrome (IBS), there is a primary hyperalgesia of the colon. Previous work, which examined these patients and normals, has not included subjects who provide a control for relevant psychological characteristics. We compared ratings of pain, following varying degrees of distension of the sigmoid colon, in normals, patients with IBS, and patients who were psychologically disturbed but without bowel symptoms. Psychological characteristics were assessed by a psychiatric interview and psychometric inventories; response to distension was tested by placing a tube in the rectosigmoid colon and successively inflating a nd deflating a balloon at its tip at 10 cm3 increments up to 50 cm3. Ratings of pain were recorded at each volume. The results indicated that the two patient groups were psychologically similar and both were more disturbed than normals. A linear relation was found between reports of pain and volume of distension in all three groups. There were no significant differences between the proportions of subjects experiencing pain in each group or the average of the ratings. There were no significant associations between the pain ratings and measures of anxiety, depression, neuroticism, and extraversion. The data do not support the hypothesis that colonic hyperalgesia is an important contributory factor in the etiology of the irritable bowel syndrome. PMID:537039

  8. Hyperalgesia, anxiety, and decreased hypoxic neuroprotection in mice lacking the adenosine A1 receptor.

    PubMed

    Johansson, B; Halldner, L; Dunwiddie, T V; Masino, S A; Poelchen, W; Giménez-Llort, L; Escorihuela, R M; Fernández-Teruel, A; Wiesenfeld-Hallin, Z; Xu, X J; Hårdemark, A; Betsholtz, C; Herlenius, E; Fredholm, B B

    2001-07-31

    Caffeine is believed to act by blocking adenosine A(1) and A(2A) receptors (A(1)R, A(2A)R), indicating that some A(1) receptors are tonically activated. We generated mice with a targeted disruption of the second coding exon of the A(1)R (A(1)R(-/-)). These animals bred and gained weight normally and had a normal heart rate, blood pressure, and body temperature. In most behavioral tests they were similar to A(1)R(+/+) mice, but A(1)R(-/-) mice showed signs of increased anxiety. Electrophysiological recordings from hippocampal slices revealed that both adenosine-mediated inhibition and theophylline-mediated augmentation of excitatory glutamatergic neurotransmission were abolished in A(1)R(-/-) mice. In A(1)R(+/-) mice the potency of adenosine was halved, as was the number of A(1)R. In A(1)R(-/-) mice, the analgesic effect of intrathecal adenosine was lost, and thermal hyperalgesia was observed, but the analgesic effect of morphine was intact. The decrease in neuronal activity upon hypoxia was reduced both in hippocampal slices and in brainstem, and functional recovery after hypoxia was attenuated. Thus A(1)Rs do not play an essential role during development, and although they significantly influence synaptic activity, they play a nonessential role in normal physiology. However, under pathophysiological conditions, including noxious stimulation and oxygen deficiency, they are important. PMID:11470917

  9. Electroacupuncture suppresses hyperalgesia and spinal Fos expression by activating the descending inhibitory system

    PubMed Central

    Li, Aihui; Wang, Yi; Xin, Giagia; Lao, Lixing; Ren, Ke; Berman, Brian M.; Zhang, Rui-Xin

    2008-01-01

    Although electroacupuncture (EA) is widely used to treat pain, its mechanisms have not been completely understood. The present study investigated the descending inhibitory system involvement in EA action. Inflammatory pain was induced by injecting complete Freund’s adjuvant subcutaneously into one hind paw of rats with dorsolateral funiculus lesions and sham-operated rats. EA treatment, 10 Hz at 3 mA, was given twice for 20 min each, once immediately post- and again 2 h post-Freund’s adjuvant at GB 30, at the junction of the lateral 1/3 and medial 2/3 of the distance between the greater trochanter and sacral hiatus. For sham EA control, acupuncture needles were inserted bilaterally into GB 30 without electrical or manual stimulation. Paw withdrawal latency to a noxious thermal stimulus was measured at baseline and 20 min after EA treatment. Compared to sham EA, EA significantly (P<0.05, n=9) increased withdrawal latency of the inflamed hind paws in the sham-operated rats but not in those with dorsolateral funiculus lesions, indicating that lesioning blocked EA-produced anti-hyperalgesia. EA, compared to sham EA, also significantly inhibited Fos expression in laminae I-II of the spinal cord in the sham-operated rats (58.4 ± 6.5 vs 35.2 ± 5.4 per section) but not in those with dorsolateral funiculus lesions. Further, EA activated serotonin- and catecholamine-containing neurons in the nucleus raphe magnus and locus coeruleus that project to the spinal cord. The results demonstrate that EA inhibits transmission of noxious messages and hyperalgesia by activating supraspinal neurons that project to the spinal cord. PMID:18001697

  10. Nostalgia-Evoked Inspiration: Mediating Mechanisms and Motivational Implications.

    PubMed

    Stephan, Elena; Sedikides, Constantine; Wildschut, Tim; Cheung, Wing-Yee; Routledge, Clay; Arndt, Jamie

    2015-10-01

    Six studies examined the nostalgia-inspiration link and its motivational implications. In Study 1, nostalgia proneness was positively associated with inspiration frequency and intensity. In Studies 2 and 3, the recollection of nostalgic (vs. ordinary) experiences increased both general inspiration and specific inspiration to engage in exploratory activities. In Study 4, serial mediational analyses supported a model in which nostalgia increases social connectedness, which subsequently fosters self-esteem, which then boosts inspiration. In Study 5, a rigorous evaluation of this serial mediational model (with a novel nostalgia induction controlling for positive affect) reinforced the idea that nostalgia-elicited social connectedness increases self-esteem, which then heightens inspiration. Study 6 extended the serial mediational model by demonstrating that nostalgia-evoked inspiration predicts goal pursuit (intentions to pursue an important goal). Nostalgia spawns inspiration via social connectedness and attendant self-esteem. In turn, nostalgia-evoked inspiration bolsters motivation. PMID:26228477

  11. CLASSICAL CONDITIONING AND PAIN: CONDITIONED ANALGESIA AND HYPERALGESIA

    PubMed Central

    Miguez, Gonzalo; Laborda, Mario A.; Miller, Ralph R.

    2013-01-01

    This article reviews situations in which stimuli produce an increase or a decrease in nociceptive responses through basic associative processes and provides an associative account of such changes. Specifically, the literature suggests that cues associated with stress can produce conditioned analgesia or conditioned hyperalgesia, depending on the properties of the conditioned stimulus (e.g., contextual cues and audiovisual cues vs. gustatory and olfactory cues, respectively) and the proprieties of the unconditioned stimulus (e.g., appetitive, aversive, or analgesic, respectively). When such cues are associated with reducers of exogenous pain (e.g., opiates), they typically increase sensitivity to pain. Overall, the evidence concerning conditioned stress-induced analgesia, conditioned hyperalagesia, conditioned tolerance to morphine, and conditioned reduction of morphine analgesia suggests that selective associations between stimuli underlie changes in pain sensitivity. PMID:24269884

  12. A new navigational mechanism mediated by ant ocelli.

    PubMed

    Schwarz, Sebastian; Wystrach, Antoine; Cheng, Ken

    2011-12-23

    Many animals rely on path integration for navigation and desert ants are the champions. On leaving the nest, ants continuously integrate their distance and direction of travel so that they always know their current distance and direction from the nest and can take a direct path to home. Distance information originates from a step-counter and directional information is based on a celestial compass. So far, it has been assumed that the directional information obtained from ocelli contribute to a single global path integrator, together with directional information from the dorsal rim area (DRA) of the compound eyes and distance information from the step-counter. Here, we show that ocelli mediate a distinct compass from that mediated by the compound eyes. After travelling a two-leg outbound route, untreated foragers headed towards the nest direction, showing that both legs of the route had been integrated. In contrast, foragers with covered compound eyes but uncovered ocelli steered in the direction opposite to the last leg of the outbound route. Our findings suggest that, unlike the DRA, ocelli cannot by themselves mediate path integration. Instead, ocelli mediate a distinct directional system, which buffers the most recent leg of a journey. PMID:21733873

  13. Education from One Generation to the Next: Mechanisms of Mediation

    ERIC Educational Resources Information Center

    Hauser-Cram, Penny

    2009-01-01

    The series of articles in this issue test conceptual models of the processes by which levels of educational attainment are passed from one generation to the next. Collectively, the investigations indicate that although proximal family processes mediate the relation between parent education and children's educational achievement, these processes…

  14. Cellular Mechanisms of Calcium-Mediated Triggered Activity

    NASA Astrophysics Data System (ADS)

    Song, Zhen

    Life-threatening cardiac arrhythmias continue to pose a major health problem. Ventricular fibrillation, which is a complex form of electrical wave turbulence in the lower chambers of the heart, stops the heart from pumping and is the largest cause of natural death in the United States. Atrial fibrillation, a related form of wave turbulence in the upper heart chambers, is in turn the most common arrhythmia diagnosed in clinical practice. Despite extensive research to date, mechanisms of cardiac arrhythmias remain poorly understood. It is well established that both spatial disorder of the refractory period of heart cells and triggered activity (TA) jointly contribute to the initiation and maintenance of arrhythmias. TA broadly refers to the abnormal generation of a single or a sequence of abnormal excitation waves from a small submillimeter region of the heart in the interval of time between two normal waves generated by the heart's natural pacemaker (the sinoatrial node). TA has been widely investigated experimentally and occurs in several pathological conditions where the intracellular concentration of free Ca2+ ions in heart cells becomes elevated. Under such conditions, Ca2+ can be spontaneously released from intracellular stores, thereby driving an electrogenic current that exchanges 3Na+ ions for one Ca2+ ion across the cell membrane. This current in turn depolarizes the membrane of heart cells after a normal excitation. If this calcium-mediated "delayed after depolarization'' (DAD) is sufficiently large, it can generate an action potential. While the arrhythmogenic importance of spontaneous Ca2+ release and DADs is well appreciated, the conditions under which they occur in heart pathologies remain poorly understood. Calcium overload is only one factor among several other factors that can promote DADs, including sympathetic nerve stimulation, different expression levels of membrane ion channels and calcium handling proteins, and different mutations of those

  15. Vibration-mediated Kondo transport in molecular junctions: conductance evolution during mechanical stretching

    PubMed Central

    Rakhmilevitch, David

    2015-01-01

    Summary The vibration-mediated Kondo effect attracted considerable theoretical interest during the last decade. However, due to lack of extensive experimental demonstrations, the fine details of the phenomenon were not addressed. Here, we analyze the evolution of vibration-mediated Kondo effect in molecular junctions during mechanical stretching. The described analysis reveals the different contributions of Kondo and inelastic transport. PMID:26734532

  16. Increased Anandamide Uptake by Sensory Neurons Contributes to Hyperalgesia in a Model of Cancer Pain

    PubMed Central

    Khasabova, Iryna A.; Holman, Michelle; Morse, Tim; Burlakova, Natalya; Coicou, Lia; Harding-Rose, Catherine; Simone, Don A.; Seybold, Virginia S.

    2013-01-01

    mechanical hyperalgesia through a CB1R-dependent mechanism and also reduced a spontaneous nocifensive behavior. The same dose reduced withdrawal responses evoked by suprathreshold mechanical stimuli in naive mice. These data support the conclusion that OMDM-1 inhibits AEA uptake by a mechanism that is independent of inhibition of FAAH and provide a rationale for the development of peripherally restricted drugs that decrease AEA uptake for the management of cancer pain. PMID:23644187

  17. Cellular Mechanisms of Calcium-Mediated Triggered Activity

    NASA Astrophysics Data System (ADS)

    Song, Zhen

    Life-threatening cardiac arrhythmias continue to pose a major health problem. Ventricular fibrillation, which is a complex form of electrical wave turbulence in the lower chambers of the heart, stops the heart from pumping and is the largest cause of natural death in the United States. Atrial fibrillation, a related form of wave turbulence in the upper heart chambers, is in turn the most common arrhythmia diagnosed in clinical practice. Despite extensive research to date, mechanisms of cardiac arrhythmias remain poorly understood. It is well established that both spatial disorder of the refractory period of heart cells and triggered activity (TA) jointly contribute to the initiation and maintenance of arrhythmias. TA broadly refers to the abnormal generation of a single or a sequence of abnormal excitation waves from a small submillimeter region of the heart in the interval of time between two normal waves generated by the heart's natural pacemaker (the sinoatrial node). TA has been widely investigated experimentally and occurs in several pathological conditions where the intracellular concentration of free Ca2+ ions in heart cells becomes elevated. Under such conditions, Ca2+ can be spontaneously released from intracellular stores, thereby driving an electrogenic current that exchanges 3Na+ ions for one Ca2+ ion across the cell membrane. This current in turn depolarizes the membrane of heart cells after a normal excitation. If this calcium-mediated "delayed after depolarization'' (DAD) is sufficiently large, it can generate an action potential. While the arrhythmogenic importance of spontaneous Ca2+ release and DADs is well appreciated, the conditions under which they occur in heart pathologies remain poorly understood. Calcium overload is only one factor among several other factors that can promote DADs, including sympathetic nerve stimulation, different expression levels of membrane ion channels and calcium handling proteins, and different mutations of those

  18. Antibody-mediated Xenograft Injury: Mechanisms and Protective Strategies

    PubMed Central

    Pierson, Richard N.

    2009-01-01

    The use of porcine organs for clinical transplantation is a promising potential solution to the shortage of human organs. Preformed anti-pig antibody is the primary cause of hyperacute rejection, while elicited antibody can contribute to subsequent “delayed” xenograft rejection. This article will review recent progress to overcome antibody mediated xenograft rejection, through modification of the host immunity and use of genetically engineered pig organs. PMID:19376229

  19. Stimulation of peripheral Kappa opioid receptors inhibits inflammatory hyperalgesia via activation of the PI3Kγ/AKT/nNOS/NO signaling pathway

    PubMed Central

    2012-01-01

    Background In addition to their central effects, opioids cause peripheral analgesia. There is evidence showing that peripheral activation of kappa opioid receptors (KORs) inhibits inflammatory pain. Moreover, peripheral μ-opioid receptor (MOR) activation are able to direct block PGE2-induced ongoing hyperalgesia However, this effect was not tested for KOR selective activation. In the present study, the effect of the peripheral activation of KORs on PGE2-induced ongoing hyperalgesia was investigated. The mechanisms involved were also evaluated. Results Local (paw) administration of U50488 (a selective KOR agonist) directly blocked, PGE2-induced mechanical hyperalgesia in both rats and mice. This effect was reversed by treating animals with L-NMMA or N-propyl-L-arginine (a selective inhibitor of neuronal nitric oxide synthase, nNOS), suggesting involvement of the nNOS/NO pathway. U50488 peripheral effect was also dependent on stimulation of PI3Kγ/AKT because inhibitors of these kinases also reduced peripheral antinociception induced by U50488. Furthermore, U50488 lost its peripheral analgesic effect in PI3Kγ null mice. Observations made in vivo were confirmed after incubation of dorsal root ganglion cultured neurons with U50488 produced an increase in the activation of AKT as evaluated by western blot analyses of its phosphorylated form. Finally, immunofluorescence of DRG neurons revealed that KOR-expressing neurons also express PI3Kγ (≅ 43%). Conclusions The present study indicates that activation of peripheral KORs directly blocks inflammatory hyperalgesia through stimulation of the nNOS/NO signaling pathway which is probably stimulated by PI3Kγ/AKT signaling. This study extends a previously study of our group suggesting that PI3Kγ/AKT/nNOS/NO is an important analgesic pathway in primary nociceptive neurons. PMID:22316281

  20. Hyperalgesia after volar wrist tattoo: a case of complex regional pain syndrome?

    PubMed

    Morte, Paul D; Magee, Larry M

    2011-03-01

    Hyperalgesia after a volar wrist tattoo with features consistent with complex regional pain syndrome and a brief literature review is presented. This is the first case of disseminated hyperalgesia reported from a tattoo. It could be related to the increased pain associated with wrist tattooing and the proximity to the palmar cutaneous branch of the median nerve. The response to prednisone was robust. Further cases may appear considering popularization of wrist tattoos by celebrities. PMID:21321489

  1. Vacancy Mediated Mechanism of Nitrogen Substitution in Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Srivastava, Deepak; Menon, Madhu; Sadanadan, Bindu; Rao, Apparao M.

    2003-01-01

    Nitrogen substitution reaction in a graphene sheet and carbon nanotubes of different diameter are investigated using the generalized tight-binding molecular dynamics method. The formation of a vacancy in curved graphene sheet or a carbon nanotube is found to cause a curvature dependent local reconstruction of the surface. Our simulations and analysis show that vacancy mediated N substitution (rather than N chemisorption) is favored on the surface of nanotubes with diameter larger than 8 nm. This predicted value of the critical minimum diameter for N incorporation is confirmed by experimental results presented.

  2. Acute and chronic fentanyl administration causes hyperalgesia independently of opioid receptor activity in mice.

    PubMed

    Waxman, Amanda R; Arout, Caroline; Caldwell, Megan; Dahan, Albert; Kest, Benjamin

    2009-10-01

    Although mu-receptor opioids are clinically important analgesics, they can also paradoxically cause hyperalgesia independently of opioid receptor activity, presumably via the action of neuroexcitatory glucoronide metabolites. However, it is unknown whether the commonly used mu-receptor opioid analgesic fentanyl, which is not subject to glucuronidation, can also induce hyperalgesia independently of opioid receptor activity. Thus, here we examined whether fentanyl increases nociception on the tail-withdrawal test in CD-1 mice concurrently treated with the opioid receptor antagonist naltrexone or in opioid receptor triple knock-out mice lacking mu, delta, and kappa opioid receptors. For both groups, an acute fentanyl bolus dose (0.25mg/kg, s.c.) and continuous fentanyl infusion (cumulative daily dose: 10mg/kg) did not cause analgesia at any time. Instead, fentanyl significantly decreased withdrawal latencies relative to pre-drug values for the next 15-60 min and for six days, respectively. MK-801 blocked and reversed hyperalgesia caused by the acute injection and continuous infusion of fentanyl, respectively, in naltrexone-treated CD-1 mice, indicating the contribution of NMDA receptors to fentanyl hyperalgesia. These data show that the synthetic opioid fentanyl causes hyperalgesia independently of prior or concurrent opioid receptor activity or analgesia. Since the biotransformation of fentanyl does not yield any known pronociceptive metabolites, these data challenge assumptions regarding the role of neuroexcitatory metabolites in opioid-induced hyperalgesia. PMID:19559072

  3. Inhibition of CaMKIIα in the Central Nucleus of Amygdala Attenuates Fentanyl-Induced Hyperalgesia in Rats.

    PubMed

    Li, Zhen; Li, Chenhong; Yin, Pingping; Wang, Zaijie Jim; Luo, Fang

    2016-10-01

    Opioid-induced hyperalgesia (OIH) is a less-studied phenomenon that has been reported in both preclinical and clinical studies. Although the underlying cause is not entirely understood, OIH is a real-life problem that affects millions of patients on a daily basis. Research has implicated the important contribution of Ca(2+)/calmodulin-dependent protein kinase IIα (CaMKIIα) to OIH at the level of spinal nociceptors. To expand our understanding of the entire brain circuitry driving OIH, in this study we investigated the role of CaMKIIα in the laterocapcular division of the central amygdala (CeLC), the conjunctive point between the spinal cord and rostro-ventral medulla. OIH was produced by repeated fentanyl administration in the rat. Correlating with the development of mechanical allodynia and thermal hyperalgesia, CaMKIIα activity was significantly elevated in the CeLC in OIH. In addition, the frequency and amplitude of spontaneous miniature excitatory postsynaptic currents (mEPSCs) in CeLC neurons were significantly increased in OIH. 2-[N-(2-hidroxyethyl)-N-(4-methoxy-benzenesulfonyl)]-amino-N-(4-chlorocinnamyl)-N-methylbenzylamine, a CaMKIIα inhibitor, dose dependently reversed sensory hypersensitivity, activation of CeLC CaMKIIα, and mEPSCs in OIH. Taken together, our data for the first time implicate a critical role of CeLC CaMKIIα in OIH. PMID:27451410

  4. Secondary hyperalgesia in the rat first degree burn model is independent of spinal cyclooxygenase and nitric oxide synthase.

    PubMed

    Sorkin, Linda S; Doom, Carmen M; Maruyama, Karly P; Nanigian, Danielle B

    2008-06-10

    Various animal models of pain are dependent on activation of different glutamate receptor subtypes. First degree burn of the paw elicits a secondary hyperalgesia that is dependent on Ca2+ permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), but not N-methyl-D-aspartate (NMDA) receptors. The present study takes advantage of that specificity by examining the effects of spinal pretreatments of agents on this secondary hyperalgesia. Rats with indwelling intrathecal catheters were pretreated with agents prior to paw injury. Mechanical withdrawal thresholds were measured before, and for three h after the injury. Spinal pretreatment with cyclooxygenase (10 and 30 microg (S)-(+)-ibuprofen; and 3 and 30 microg ketorolac) and nitric oxide synthase (33 and 100 microg N(G) Nitro-L-arginine methyl ester hydrochloride (L-NAME) and 10 microg thiocitrulline) inhibitors resulted in no specific anti-allodynia. In contrast, ziconotide (0.3, 1.0 and 3 microg), the N-type voltage gated calcium channel antagonist was very effective in blocking burn-induced sensitivity at all doses used. l-type (Diltiazam 230 microg) and P-type (Agatoxin IVA 0.3 microg) calcium channel blockers produced intermediate effects. Thus, cyclooxygenase and nitric oxide synthase are assumed not to be downstream of Ca2+ permeable AMPA receptors. Voltage gated calcium channels blockers could exert their effects either pre- or post-synaptically. PMID:18440503

  5. Innate Immune Regulation by STAT-mediated Transcriptional Mechanisms

    PubMed Central

    Li, Haiyan S.; Watowich, Stephanie S.

    2014-01-01

    Summary The term innate immunity typically refers to a quick but nonspecific host defense response against invading pathogens. The innate immune system comprises particular immune cell populations, epithelial barriers, and numerous secretory mediators including cytokines, chemokines, and defense peptides. Innate immune cells are also now recognized to play important contributing roles in cancer and pathological inflammatory conditions. Innate immunity relies on rapid signal transduction elicited upon pathogen recognition via pattern recognition receptors (PRRs) and cell:cell communication conducted by soluble mediators, including cytokines. A majority of cytokines involved in innate immune signaling use a molecular cascade encompassing receptor-associated Jak protein tyrosine kinases and STAT (signal transducer and activator of transcription) transcriptional regulators. Here, we focus on roles for STAT proteins in three major innate immune subsets: neutrophils, macrophages, and dendritic cells (DCs). While knowledge in this area is only now emerging, understanding the molecular regulation of these cell types is necessary for developing new approaches to treat human disorders such as inflammatory conditions, autoimmunity, and cancer. PMID:25123278

  6. Is the Volume of the Caudate Nuclei Associated With Area of Secondary Hyperalgesia? – Protocol for a 3-Tesla MRI Study of Healthy Volunteers

    PubMed Central

    Asghar, Mohammad Sohail; Wetterslev, Jørn; Pipper, Christian Bressen; Johan Mårtensson, Johan; Becerra, Lino; Christensen, Anders; Nybing, Janus Damm; Havsteen, Inger; Boesen, Mikael; Dahl, Jørgen Berg

    2016-01-01

    Background Experience and development of pain may be influenced by a number of physiological, psychological, and psychosocial factors. In a previous study we found differences in neuronal activation to noxious stimulation, and microstructural neuroanatomical differences, when comparing healthy volunteers with differences in size of the area of secondary hyperalgesia following a standardized burn injury. Objective We aim to investigate the degree of association between the volume of pain-relevant structures in the brain and the size of the area of secondary hyperalgesia following brief thermal sensitization. Methods The study consists of one experimental day, in which whole-brain magnetic resonance imaging (MRI) scans will be conducted including T1-weighed three-dimensional anatomy scan, diffusion tensor imaging, and resting state functional MRI. Before the experimental day, all included participants will undergo experimental pain testing in a parallel study (Clinicaltrials.gov Identifier: NCT02527395). Results from this experimental pain testing, as well as the size of the area of secondary hyperalgesia from the included participants, will be extracted from this parallel study. Results The association between the volume of pain-relevant structures in the brain and the area of secondary hyperalgesia will be investigated by linear regression of the estimated best linear unbiased predictors on the individual volumes of the pain relevant brain structures. Conclusions We plan to investigate the association between experimental pain testing parameters and the volume, connectivity, and resting state activity of pain-relevant structures in the brain. These results may improve our knowledge of the mechanisms responsible for the development of acute and chronic pain. ClinicalTrial Danish Research Ethics Committee (identifier: H-15010473). Danish Data Protection Agency (identifier: RH-2015-149). Clinicaltrials.gov NCT02567318; http://clinicaltrials.gov/ct2/show/NCT02567318

  7. Mediated coalescence: a possible mechanism for tumor cellular heterogeneity

    PubMed Central

    Ambrose, Joseph; Livitz, Michelle; Wessels, Deborah; Kuhl, Spencer; Lusche, Daniel F; Scherer, Amanda; Voss, Edward; Soll, David R

    2015-01-01

    Recently, we demonstrated that tumorigenic cell lines and fresh tumor cells seeded in a 3D Matrigel model, first grow as clonal islands (primary aggregates), then coalesce through the formation and contraction of cellular cables. Non-tumorigenic cell lines and cells from normal tissue form clonal islands, but do not form cables or coalesce. Here we show that as little as 5% tumorigenic cells will actively mediate coalescence between primary aggregates of majority non-tumorigenic or non-cancerous cells, by forming cellular cables between them. We suggest that this newly discovered, specialized characteristic of tumorigenic cells may explain, at least in part, why tumors contain primarily non-tumorigenic cells. PMID:26807328

  8. The mechanisms of HAMP-mediated signaling in transmembrane receptors.

    PubMed

    Ferris, Hedda U; Dunin-Horkawicz, Stanislaw; Mondéjar, Laura García; Hulko, Michael; Hantke, Klaus; Martin, Jörg; Schultz, Joachim E; Zeth, Kornelius; Lupas, Andrei N; Coles, Murray

    2011-03-01

    HAMP domains mediate signal transduction in over 7500 enzyme-coupled receptors represented in all kingdoms of life. The HAMP domain of the putative archaeal receptor Af1503 has a parallel, dimeric, four-helical coiled coil structure, but with unusual core packing, related to canonical packing by concerted axial rotation of the helices. This has led to the gearbox model for signal transduction, whereby the alternate packing modes correspond to signaling states. Here we present structures of a series of Af1503 HAMP variants. We show that substitution of a conserved small side chain within the domain core (A291) for larger residues induces a gradual transition in packing mode, involving both changes in helix rotation and bundle shape, which are most prominent at the C-terminal, output end of the domain. These are correlated with activity and ligand response in vitro and in vivo by incorporating Af1503 HAMP into mycobacterial adenylyl cyclase assay systems. PMID:21397188

  9. Chirality-Mediated Mechanical and Structural Properties of Oligopeptide Hydrogels

    SciTech Connect

    Taraban, Marc B.; Feng, Yue; Hammouda, Boualem; Hyland, Laura L.; Yu, Y. Bruce

    2012-10-29

    The origin and the effects of homochirality in the biological world continuously stimulate numerous hypotheses and much debate. This work attempts to look at the biohomochirality issue from a different angle - the mechanical properties of the bulk biomaterial and their relation to nanoscale structures. Using a pair of oppositely charged peptides that co-assemble into hydrogels, we systematically investigated the effect of chirality on the mechanical properties of these hydrogels through different combinations of syndiotactic and isotactic peptides. It was found that homochirality confers mechanical advantage, resulting in a higher elastic modulus and strain yield value. Yet, heterochirality confers kinetic advantage, resulting in faster gelation. Structurally, both homochiral and heterochiral hydrogels are made of fibers interconnected by lappet-like webs, but the homochiral peptide fibers are thicker and denser. These results highlight the possible role of biohomochirality in the evolution and/or natural selection of biomaterials.

  10. Opioid-induced hyperalgesia: when pain killers make pain worse.

    PubMed

    Kaneria, Anshuni

    2014-01-01

    A 44-year-old woman had a temporal glioma and was admitted to the hospice with pain that was not controlled despite escalating opioids. Her pain levels rose after every dose increase resulting now in continuous pain, making her very low in mood. Her short-term memory had also declined in a stepwise fashion with each increase in opioids. Additionally, her poor health had had a detrimental effect on family life. Physical examination was difficult due to allodynia but no major abnormality was found. The team suspected opioid-induced hyperalgesia and decided to cut the patient's opioids by one-third initially. This immediately improved the overall pain. The opioids continued to be decreased incrementally every 1-2 days until the pain had disappeared completely. She was stabilised on a dose almost one-seventh of her original regime. Mood and memory also improved as opioids decreased and she was discharged home after 8 days. PMID:24899014

  11. The mechanosensitive APJ internalization via clathrin-mediated endocytosis: A new molecular mechanism of cardiac hypertrophy.

    PubMed

    He, Lu; Chen, Linxi; Li, Lanfang

    2016-05-01

    The G protein-coupled receptor APJ elicits cellular response to diverse extracellular stimulus. Accumulating evidence reveals that APJ receptor plays a prominent role in the cardiomyocyte adapting to hypertrophic stimulation. At present, it remains obscure that the regulatory mechanism of APJ receptor in myocardial hypertrophy. The natural endogenous ligands apelin and Elabela as well as agonists maintain high affinity for the APJ receptor and drive its internalization. Ligand-activated receptor internalization is mainly performed by clathrin-mediated endocytic pathway. Simultaneously, clathrin-mediated endocytosis takes participate in the occurrence and development of cardiac hypertrophy. In this study, we hypothesize that natural ligands and agonists induce the mechanosensitive APJ internalization via clathrin-mediated endocytosis. APJ internalization may contribute to the development of cardiac hypertrophy. The mechanosensitive APJ internalization via clathrin-mediated endocytosis may be a new molecular mechanism of cardiac hypertrophy. PMID:27063076

  12. Extended access to nicotine leads to a CRF1 receptor dependent increase in anxiety-like behavior and hyperalgesia in rats

    PubMed Central

    Cohen, Ami; Treweek, Jennifer; Edwards, Scott; Leão, Rodrigo Molini; Schulteis, Gery; Koob, George F.; George, Olivier

    2013-01-01

    Background Tobacco dependence is associated with the emergence of negative emotional states during withdrawal, including anxiety and nociceptive hypersensitivity. However, the current animal models of nicotine dependence have focused on the mechanisms that mediate the acute reinforcing effects of nicotine and failed to link increased anxiety and pain during abstinence with excessive nicotine self-administration. Here, we tested the hypothesis that the activation of corticotropin-releasing factor-1 (CRF1) receptors and emergence of the affective and motivational effects of nicotine abstinence only occur in rats with long access (> 21 h/day, LgA) and not short (1 h/day, ShA) access to nicotine self-administration. Methods ShA and LgA rats were tested for anxiety-like behavior, nociceptive thresholds, somatic signs of withdrawal, and nicotine intake after 3 days of abstinence. The role of CRF1 receptors during abstinence was tested using systemic or intracerebral infusion of MPZP, a CRF1 receptor antagonist, in the central nucleus of the amygdala (CeA). Results LgA but not ShA rats exhibited abstinence-induced increases in anxiety-like behavior and nociceptive hypersensitivity, which both predicted subsequent excessive nicotine intake and were prevented by systemic administration of MPZP. Intra-CeA MPZP infusion prevented abstinence-induced increases in nicotine intake and nociceptive hypersensitivity. Conclusions These findings demonstrate that the model of short access to nicotine self-administration has limited validity for tobacco dependence, highlight the translational relevance of the model of extended-intermittent access to nicotine self-administration for tobacco dependence, and demonstrate that activation of CRF1 receptors is required for the emergence of abstinence-induced anxiety-like behavior, hyperalgesia, and excessive nicotine intake. PMID:23869743

  13. Caloric restriction as a mechanism mediating resistance to environmental disease.

    PubMed Central

    Frame, L T; Hart, R W; Leakey, J E

    1998-01-01

    It has been observed that susceptibility to many degenerative diseases increases concurrently with industrialization and rising living standards. Although epidemiologic studies suggest that specific environmental and dietary factors may be important, caloric intake alone (as reflected in body size) may account for much of the differential risk observed among diverse human populations. It has been suggested from animal studies that caloric intake may be the primary effector for many hormonal, metabolic, physiologic, and behavioral responses that coordinate reproductive strategy to apparent availability of food. When caloric intake is excessive, particularly at critical developmental stages, physiologic priorities are set for body growth and fecundity rather than for endurance and longevity. The converse occurs during periods of famine, thus increasing the probability that sufficient individuals survive to restore the population when conditions improve. Calorically restricted rodents have significantly longer reproductive and total life spans than their ad libitum-fed controls and exhibit a spectrum of biochemical and physiologic alterations that characterize their adaptation to reduced intake. These include reduced stature, hypercorticism in the absence of elevated adrenocorticotropic hormone levels, increased metabolic efficiency, decreased mitogenic response coupled with increased rates of apoptosis, reduced inflammatory response, induction of stress proteins and DNA repair enzymes, altered drug-metabolizing enzyme expression, and modified cell-mediated immune function. The overall profile of these changes is one of improved defense against environmental stress. This has been suggested as the mechanistic basis for the protective effects of low body weight on radiation and chemically induced cancers in experimental animals. It may also explain the significantly higher thresholds of acute toxicity observed when calorically restricted rodents are exposed to certain

  14. Mechanisms of abscisic acid-mediated control of stomatal aperture.

    PubMed

    Munemasa, Shintaro; Hauser, Felix; Park, Jiyoung; Waadt, Rainer; Brandt, Benjamin; Schroeder, Julian I

    2015-12-01

    Drought stress triggers an increase in the level of the plant hormone abscisic acid (ABA), which initiates a signaling cascade to close stomata and reduce water loss. Recent studies have revealed that guard cells control cytosolic ABA concentration through the concerted actions of biosynthesis, catabolism as well as transport across membranes. Substantial progress has been made at understanding the molecular mechanisms of how the ABA signaling core module controls the activity of anion channels and thereby stomatal aperture. In this review, we focus on our current mechanistic understanding of ABA signaling in guard cells including the role of the second messenger Ca(2+) as well as crosstalk with biotic stress responses. PMID:26599955

  15. Acid-induced hyperalgesia and anxio-depressive comorbidity in rats.

    PubMed

    Liu, Yu-Ting; Shao, Yen-Wen; Yen, Chen-Tung; Shaw, Fu-Zen

    2014-05-28

    Fibromyalgia is a prevalent disorder characterized by chronic widespread pain (CWP) and complex comorbid symptoms. A CWP model is developed through repeated unilateral intramuscular injections of acid saline resulting in bilateral mechanical hyperalgesia in rats. The present study aims to evaluate whether both anxious and depressive comorbidities exist in this acid-induced pain model, similarly to patients with CWP syndromes. The anxiety-like behaviors were evaluated using the open field and elevated plus maze tests, and depression-like behaviors were measured by the forced swimming, sucrose consumption, and sucrose preference tests. The pain group receiving acidic saline displayed significantly lower paw withdrawal thresholds for 4weeks than animals in the vehicle group after repetitive intramuscular injections. The pain group showed a significantly shorter duration of exploring the central zone of the open field and the open arms of the elevated plus maze compared to the vehicle group. The pain group had a significantly lower preference for and consumption of the hedonic sucrose. Moreover, rats with chronic pain showed significantly longer immobility than the vehicle group in the forced swimming test. The results indicate that psychiatric behaviors are exacerbated in the CWP model. This study provides evidence for the validity of the acid-induced pain model analogous to patients with CWP syndromes. PMID:24726391

  16. Molecular mechanisms mediating vascular calcification: role of matrix Gla protein.

    PubMed

    Proudfoot, Diane; Shanahan, Catherine M

    2006-10-01

    Patients with chronic kidney disease (CKD) have a higher incidence of vascular calcification and a greatly increased risk of cardiovascular death. The mechanisms involved in the accelerated vascular calcification observed in CKD have recently become clearer, leading to the hypothesis that a lack of natural inhibitors of calcification may trigger calcium deposition. One of these inhibitory factors, matrix Gla protein (MGP), is the focus of the present review. MGP, originally isolated from bone, is a vitamin K-dependent protein that is also highly expressed by vascular smooth muscle cells. MGP has been confirmed as a calcification-inhibitor in numerous studies; however, its mechanism of action is not completely understood. It potentially acts in several ways to regulate calcium deposition including: (i) binding calcium ions and crystals; (ii) antagonizing bone morphogenetic protein and altering cell differentiation; (iii) binding to extracellular matrix components; and (iv) regulating apoptosis. Its expression is regulated by several factors including retinoic acid, vitamin D and extracellular calcium ions, and a reduced form of vitamin K (KH2) is important in maintaining MGP in an active form. Therefore, strategies aimed at increasing its expression and activity may be beneficial in tipping the balance in favour of inhibition of calcification in CKD. PMID:17014561

  17. Myofibroblast-mediated mechanisms of pathological remodelling of the heart.

    PubMed

    Weber, Karl T; Sun, Yao; Bhattacharya, Syamal K; Ahokas, Robert A; Gerling, Ivan C

    2013-01-01

    The syncytium of cardiomyocytes in the heart is tethered within a matrix composed principally of type I fibrillar collagen. The matrix has diverse mechanical functions that ensure the optimal contractile efficiency of this muscular pump. In the diseased heart, cardiomyocytes are lost to necrotic cell death, and phenotypically transformed fibroblast-like cells-termed 'myofibroblasts'-are activated to initiate a 'reparative' fibrosis. The structural integrity of the myocardium is preserved by this scar tissue, although at the expense of its remodelled architecture, which has increased tissue stiffness and propensity to arrhythmias. A persisting population of activated myofibroblasts turns this fibrous tissue into a living 'secretome' that generates angiotensin II and its type 1 receptor, and fibrogenic growth factors (such as transforming growth factor-β), all of which collectively act as a signal-transducer-effector signalling pathway to type I collagen synthesis and, therefore, fibrosis. Persistent myofibroblasts, and the resultant fibrous tissue they produce, cause progressive adverse myocardial remodelling, a pathological hallmark of the failing heart irrespective of its etiologic origin. Herein, we review relevant cellular, subcellular, and molecular mechanisms integral to cardiac fibrosis and consequent remodelling of atria and ventricles with a heterogeneity in cardiomyocyte size. Signalling pathways that antagonize collagen fibrillogenesis provide novel strategies for cardioprotection. PMID:23207731

  18. Morphogenesis of protrusions from confined lipid bilayers mediated by mechanics

    NASA Astrophysics Data System (ADS)

    Arroyo, Marino; Staykova, Margarita; Rahimi, Mohammad; Stone, Howard A.

    2012-02-01

    Biological membranes adopt a wide range of shapes that structure and give functionality to cells, compartmentalizing the cytosol, forming organelles, or regulating their area. The formation, stabilization, and remodeling of these structures is generally attributed to localized forces or to biochemical processes (insertion of proteins, active compositional regulation). Noting that in the crowded intra and extra-cellular environments membranes are highly constrained, we explore to what extent can mechanics explain the shape of protrusions out of confined membranes. For this purpose, we developed an in-vitro system coupling a lipid bilayer to the strain-controlled deformation of an elastic sheet (Staykova et al, PNAS 108, 2011). We show that upon contracting the elastic support, tubular or spherical protrusions grow out of the adhered membrane, which can be reversibly controlled with strain and osmolarity without resorting to localized forces or chemical alterations of the bilayer. The morphologies produced by our minimal system are ubiquitous in cells, suggesting mechanics may be a simple and generic organizing principle. We can understand most of our observations in terms of a phase diagram accounting for elasticity, adhesion, and the limited amount of area and volume available.

  19. Molecular mechanisms of CRISPR-mediated microbial immunity.

    PubMed

    Gasiunas, Giedrius; Sinkunas, Tomas; Siksnys, Virginijus

    2014-02-01

    Bacteriophages (phages) infect bacteria in order to replicate and burst out of the host, killing the cell, when reproduction is completed. Thus, from a bacterial perspective, phages pose a persistent lethal threat to bacterial populations. Not surprisingly, bacteria evolved multiple defense barriers to interfere with nearly every step of phage life cycles. Phages respond to this selection pressure by counter-evolving their genomes to evade bacterial resistance. The antagonistic interaction between bacteria and rapidly diversifying viruses promotes the evolution and dissemination of bacteriophage-resistance mechanisms in bacteria. Recently, an adaptive microbial immune system, named clustered regularly interspaced short palindromic repeats (CRISPR) and which provides acquired immunity against viruses and plasmids, has been identified. Unlike the restriction–modification anti-phage barrier that subjects to cleavage any foreign DNA lacking a protective methyl-tag in the target site, the CRISPR–Cas systems are invader-specific, adaptive, and heritable. In this review, we focus on the molecular mechanisms of interference/immunity provided by different CRISPR–Cas systems. PMID:23959171

  20. Gap junction-mediated electrical transmission: regulatory mechanisms and plasticity

    PubMed Central

    Pereda, Alberto E.; Curti, Sebastian; Hoge, Gregory; Cachope, Roger; Flores, Carmen E.; Rash, John E.

    2012-01-01

    The term synapse applies to cellular specializations that articulate the processing of information within neural circuits by providing a mechanism for the transfer of information between two different neurons. There are two main modalities of synaptic transmission: chemical and electrical. While most efforts have been dedicated to the understanding of the properties and modifiability of chemical transmission, less is still known regarding the plastic properties of electrical synapses, whose structural correlate is the gap junction. A wealth of data indicates that, rather than passive intercellular channels, electrical synapses are more dynamic and modifiable than was generally perceived. This article will discuss the factors determining the strength of electrical transmission and review current evidence demonstrating its dynamic properties. Like their chemical counterparts, electrical synapses can also be plastic and modifiable. PMID:22659675

  1. Effects of extracorporeal shock-wave lithotripsy on referred hyperalgesia from renal/ureteral calculosis.

    PubMed

    Giamberardino, M A; de Bigontina, P; Martegiani, C; Vecchiet, L

    1994-01-01

    In patients suffering from colics due to calculosis of one upper urinary tract the evolution in time of referred parietal hyperalgesia after stone fragment elimination promoted by extracorporeal shock wave lithotripsy (ESWL) was studied. Before ESWL, all patients presented clinical evidence (positivity to dermographism and Head's procedure, pinch palpation, digital pressure and Giordano's manoeuver) and instrumental signs (significant lowering of pain threshold to electrical tissue stimulation) of cutaneous, subcutaneous and muscular tissue hyperalgesia in the lumbar region of the affected side. After ESWL, hyperalgesia decreased in the three tissues, as shown by progressive change in the clinical tests and an increase in pain threshold to electrical stimulation in relation to the extent of stone fragment expulsion. In the stone-free condition, hyperalgesia had disappeared in the skin but remained to a mild and moderate extent in the subcutaneous tissue and muscle respectively. It is concluded that the persistence in time of referred hyperalgesia is only in part linked to the continuing presence and activity of the stone in the urinary tract. To a certain extent, the phenomenon seems to become independent of the primary focus, possibly as a result of plastic neuronal changes in the central nervous system which, triggered by afferent visceral inputs, are maintained even after their removal. PMID:8159443

  2. Expression and Regulation of Cav3.2 T-Type Calcium Channels during Inflammatory Hyperalgesia in Mouse Dorsal Root Ganglion Neurons.

    PubMed

    Watanabe, Masaya; Ueda, Takashi; Shibata, Yasuhiro; Kumamoto, Natsuko; Shimada, Shoichi; Ugawa, Shinya

    2015-01-01

    The Cav3.2 isoform of the T-type calcium channel is expressed in primary sensory neurons of the dorsal root ganglion (DRG), and these channels contribute to nociceptive and neuropathic pain in rats. However, there are conflicting reports on the roles of these channels in pain processing in rats and mice. In addition, the function of T-type channels in persistent inflammatory hyperalgesia is poorly understood. We performed behavioral and comprehensive histochemical analyses to characterize Cav3.2-expressing DRG neurons and examined the regulation of T-type channels in DRGs from C57BL/6 mice with carrageenan-induced inflammatory hyperalgesia. We show that approximately 20% of mouse DRG neurons express Cav3.2 mRNA and protein. The size of the majority of Cav3.2-positive DRG neurons (69 ± 8%) ranged from 300 to 700 μm2 in cross-sectional area and 20 to 30 μm in estimated diameter. These channels co-localized with either neurofilament-H (NF-H) or peripherin. The peripherin-positive cells also overlapped with neurons that were positive for isolectin B4 (IB4) and calcitonin gene-related peptide (CGRP) but were distinct from transient receptor potential vanilloid 1 (TRPV1)-positive neurons during normal mouse states. In mice with carrageenan-induced inflammatory hyperalgesia, Cav3.2 channels, but not Cav3.1 or Cav3.3 channels, were upregulated in ipsilateral DRG neurons during the sub-acute phase. The increased Cav3.2 expression partially resulted from an increased number of Cav3.2-immunoreactive neurons; this increase in number was particularly significant for TRPV1-positive neurons. Finally, preceding and periodic intraplantar treatment with the T-type calcium channel blockers mibefradil and NNC 55-0396 markedly reduced and reversed mechanical hyperalgesia during the acute and sub-acute phases, respectively, in mice. These data suggest that Cav3.2 T-type channels participate in the development of inflammatory hyperalgesia, and this channel might play an even greater

  3. Selective T-Type Calcium Channel Blockade Alleviates Hyperalgesia in ob/ob Mice

    PubMed Central

    Latham, Janelle R.; Pathirathna, Sriyani; Jagodic, Miljen M.; Joo Choe, Won; Levin, Michaela E.; Nelson, Michael T.; Yong Lee, Woo; Krishnan, Kathiresan; Covey, Douglas F.; Todorovic, Slobodan M.; Jevtovic-Todorovic, Vesna

    2009-01-01

    OBJECTIVE Morbid obesity may be accompanied by diabetes and painful diabetic neuropathy, a poorly understood condition that is manifested by mechanical or thermal allodynia and hyperalgesia. Recent studies have highlighted the importance of T-type calcium channels (T-channels) in peripheral nociception; therefore, our goal was to examine the function of these channels in the pathophysiology and development of painful diabetic neuropathy. RESEARCH DESIGN AND METHODS In vivo testing of mechanical and thermal sensation, morphometric peripheral nerve studies, and electrophysiological and biochemical measurements were used to characterize the role of T-channels and the development of painful diabetic neuropathy in leptin-deficient (ob/ob) mice. RESULTS We found that ob/ob mice developed significant mechanical and thermal hypersensitivity early in life that coincided with hyperglycemia and was readily reversed with insulin therapy. These disturbances were accompanied by significant biophysical and biochemical modulation of T-channels in dorsal root ganglion neurons as measured by a large increase in the amplitude of T-currents and the expression of mRNA. The most prevalent subtype, α1H (Cav3.2), was most strongly affected. Moreover, (3β,5α,17β)-17-hydroxyestrane-3-carbonitrile (ECN), a novel neuroactive steroid and selective T-channel antagonist, provided dose-dependent alleviation of neuropathic thermal and mechanical hypersensitivity in diabetic ob/ob mice. CONCLUSIONS Our results indicate that pharmacological antagonism of T-channels is potentially an important novel therapeutic approach for the management of painful diabetic neuropathy. PMID:19651818

  4. Epigenetic mechanisms mediating vulnerability and resilience to psychiatric disorders.

    PubMed

    Dudley, Kevin J; Li, Xiang; Kobor, Michael S; Kippin, Tod E; Bredy, Timothy W

    2011-06-01

    The impact that stressful encounters have upon long-lasting behavioural phenotypes is varied. Whereas a significant proportion of the population will develop "stress-related" conditions such as post-traumatic stress disorder or depression in later life, the majority are considered "resilient" and are able to cope with stress and avoid such psychopathologies. The reason for this heterogeneity is undoubtedly multi-factorial, involving a complex interplay between genetic and environmental factors. Both genes and environment are of critical importance when it comes to developmental processes, and it appears that subtle differences in either of these may be responsible for altering developmental trajectories that confer vulnerability or resilience. At the molecular level, developmental processes are regulated by epigenetic mechanisms, with recent clinical and pre-clinical data obtained by ourselves and others suggesting that epigenetic differences in various regions of the brain are associated with a range of psychiatric disorders, including many that are stress-related. Here we provide an overview of how these epigenetic differences, and hence susceptibility to psychiatric disorders, might arise through exposure to stress-related factors during critical periods of development. PMID:21251925

  5. Surface charge of gold nanoparticles mediates mechanism of toxicity

    NASA Astrophysics Data System (ADS)

    Schaeublin, Nicole M.; Braydich-Stolle, Laura K.; Schrand, Amanda M.; Miller, John M.; Hutchison, Jim; Schlager, John J.; Hussain, Saber M.

    2011-02-01

    Recently gold nanoparticles (Au NPs) have shown promising biological and military applications due to their unique electronic and optical properties. However, little is known about their biocompatibility in the event that they come into contact with a biological system. In the present study, we have investigated whether modulating the surface charge of 1.5 nm Au NPs induced changes in cellular morphology, mitochondrial function, mitochondrial membrane potential (MMP), intracellular calcium levels, DNA damage-related gene expression, and of p53 and caspase-3 expression levels after exposure in a human keratinocyte cell line (HaCaT). The evaluation of three different Au NPs (positively charged, neutral, and negatively charged) showed that cell morphology was disrupted by all three NPs and that they demonstrated a dose-dependent toxicity; the charged Au NPs displayed toxicity as low as 10 µg ml-1 and the neutral at 25 µg ml-1. Furthermore, there was significant mitochondrial stress (decreases in MMP and intracellular Ca2+ levels) following exposure to the charged Au NPs, but not the neutral Au NPs. In addition to the differences observed in the MMP and Ca2+ levels, up or down regulation of DNA damage related gene expression suggested a differential cell death mechanism based on whether or not the Au NPs were charged or neutral. Additionally, increased nuclear localization of p53 and caspase-3 expression was observed in cells exposed to the charged Au NPs, while the neutral Au NPs caused an increase in both nuclear and cytoplasmic p53 expression. In conclusion, these results indicate that surface charge is a major determinant of how Au NPs impact cellular processes, with the charged NPs inducing cell death through apoptosis and neutral NPs leading to necrosis.Recently gold nanoparticles (Au NPs) have shown promising biological and military applications due to their unique electronic and optical properties. However, little is known about their biocompatibility in the

  6. Central Mechanisms Mediating Thrombospondin-4-induced Pain States.

    PubMed

    Park, John; Yu, Yanhui Peter; Zhou, Chun-Yi; Li, Kang-Wu; Wang, Dongqing; Chang, Eric; Kim, Doo-Sik; Vo, Benjamin; Zhang, Xia; Gong, Nian; Sharp, Kelli; Steward, Oswald; Vitko, Iuliia; Perez-Reyes, Edward; Eroglu, Cagla; Barres, Ben; Zaucke, Frank; Feng, Guoping; Luo, Z David

    2016-06-17

    Peripheral nerve injury induces increased expression of thrombospondin-4 (TSP4) in spinal cord and dorsal root ganglia that contributes to neuropathic pain states through unknown mechanisms. Here, we test the hypothesis that TSP4 activates its receptor, the voltage-gated calcium channel Cavα2δ1 subunit (Cavα2δ1), on sensory afferent terminals in dorsal spinal cord to promote excitatory synaptogenesis and central sensitization that contribute to neuropathic pain states. We show that there is a direct molecular interaction between TSP4 and Cavα2δ1 in the spinal cord in vivo and that TSP4/Cavα2δ1-dependent processes lead to increased behavioral sensitivities to stimuli. In dorsal spinal cord, TSP4/Cavα2δ1-dependent processes lead to increased frequency of miniature and amplitude of evoked excitatory post-synaptic currents in second-order neurons as well as increased VGlut2- and PSD95-positive puncta, indicative of increased excitatory synapses. Blockade of TSP4/Cavα2δ1-dependent processes with Cavα2δ1 ligand gabapentin or genetic Cavα2δ1 knockdown blocks TSP4 induced nociception and its pathological correlates. Conversely, TSP4 antibodies or genetic ablation blocks nociception and changes in synaptic transmission in mice overexpressing Cavα2δ1 Importantly, TSP4/Cavα2δ1-dependent processes also lead to similar behavioral and pathological changes in a neuropathic pain model of peripheral nerve injury. Thus, a TSP4/Cavα2δ1-dependent pathway activated by TSP4 or peripheral nerve injury promotes exaggerated presynaptic excitatory input and evoked sensory neuron hyperexcitability and excitatory synaptogenesis, which together lead to central sensitization and pain state development. PMID:27129212

  7. Putative mechanisms mediating tolerance for audiovisual stimulus onset asynchrony.

    PubMed

    Bhat, Jyoti; Miller, Lee M; Pitt, Mark A; Shahin, Antoine J

    2015-03-01

    Audiovisual (AV) speech perception is robust to temporal asynchronies between visual and auditory stimuli. We investigated the neural mechanisms that facilitate tolerance for audiovisual stimulus onset asynchrony (AVOA) with EEG. Individuals were presented with AV words that were asynchronous in onsets of voice and mouth movement and judged whether they were synchronous or not. Behaviorally, individuals tolerated (perceived as synchronous) longer AVOAs when mouth movement preceded the speech (V-A) stimuli than when the speech preceded mouth movement (A-V). Neurophysiologically, the P1-N1-P2 auditory evoked potentials (AEPs), time-locked to sound onsets and known to arise in and surrounding the primary auditory cortex (PAC), were smaller for the in-sync than the out-of-sync percepts. Spectral power of oscillatory activity in the beta band (14-30 Hz) following the AEPs was larger during the in-sync than out-of-sync perception for both A-V and V-A conditions. However, alpha power (8-14 Hz), also following AEPs, was larger for the in-sync than out-of-sync percepts only in the V-A condition. These results demonstrate that AVOA tolerance is enhanced by inhibiting low-level auditory activity (e.g., AEPs representing generators in and surrounding PAC) that code for acoustic onsets. By reducing sensitivity to acoustic onsets, visual-to-auditory onset mapping is weakened, allowing for greater AVOA tolerance. In contrast, beta and alpha results suggest the involvement of higher-level neural processes that may code for language cues (phonetic, lexical), selective attention, and binding of AV percepts, allowing for wider neural windows of temporal integration, i.e., greater AVOA tolerance. PMID:25505102

  8. Hypothalamic oxytocin mediates adaptation mechanism against chronic stress in rats

    PubMed Central

    Zheng, Jun; Babygirija, Reji; Bülbül, Mehmet; Cerjak, Diana; Ludwig, Kirk

    2010-01-01

    Accumulation of continuous life stress (chronic stress) often causes gastric symptoms. Although central oxytocin has antistress effects, the role of central oxytocin in stress-induced gastric dysmotility remains unknown. Solid gastric emptying was measured in rats receiving acute restraint stress, 5 consecutive days of repeated restraint stress (chronic homotypic stress), and 7 consecutive days of varying types of stress (chronic heterotypic stress). Oxytocin and oxytocin receptor antagonist were administered intracerebroventricularly (icv). Expression of corticotropin-releasing factor (CRF) mRNA and oxytocin mRNA in the paraventricular nucleus (PVN) of the hypothalamus was evaluated by real-time RT-PCR. The changes of oxytocinergic neurons in the PVN were evaluated by immunohistochemistry. Acute stress delayed gastric emptying, and the delayed gastric emptying was completely restored after 5 consecutive days of chronic homotypic stress. In contrast, delayed gastric emptying persisted following chronic heterotypic stress. The restored gastric emptying following chronic homotypic stress was antagonized by icv injection of an oxytocin antagonist. Icv injection of oxytocin restored delayed gastric emptying induced by chronic heterotypic stress. CRF mRNA expression, which was significantly increased in response to acute stress and chronic heterotypic stress, returned to the basal levels following chronic homotypic stress. In contrast, oxytocin mRNA expression was significantly increased following chronic homotypic stress. The number of oxytocin-immunoreactive cells was increased following chronic homotypic stress at the magnocellular part of the PVN. Icv injection of oxytocin reduced CRF mRNA expression induced by acute stress and chronic heterotypic stress. It is suggested that the adaptation mechanism to chronic stress may involve the upregulation of oxytocin expression in the hypothalamus, which in turn attenuates CRF expression. PMID:20689056

  9. Hypothalamic oxytocin mediates adaptation mechanism against chronic stress in rats.

    PubMed

    Zheng, Jun; Babygirija, Reji; Bülbül, Mehmet; Cerjak, Diana; Ludwig, Kirk; Takahashi, Toku

    2010-10-01

    Accumulation of continuous life stress (chronic stress) often causes gastric symptoms. Although central oxytocin has antistress effects, the role of central oxytocin in stress-induced gastric dysmotility remains unknown. Solid gastric emptying was measured in rats receiving acute restraint stress, 5 consecutive days of repeated restraint stress (chronic homotypic stress), and 7 consecutive days of varying types of stress (chronic heterotypic stress). Oxytocin and oxytocin receptor antagonist were administered intracerebroventricularly (icv). Expression of corticotropin-releasing factor (CRF) mRNA and oxytocin mRNA in the paraventricular nucleus (PVN) of the hypothalamus was evaluated by real-time RT-PCR. The changes of oxytocinergic neurons in the PVN were evaluated by immunohistochemistry. Acute stress delayed gastric emptying, and the delayed gastric emptying was completely restored after 5 consecutive days of chronic homotypic stress. In contrast, delayed gastric emptying persisted following chronic heterotypic stress. The restored gastric emptying following chronic homotypic stress was antagonized by icv injection of an oxytocin antagonist. Icv injection of oxytocin restored delayed gastric emptying induced by chronic heterotypic stress. CRF mRNA expression, which was significantly increased in response to acute stress and chronic heterotypic stress, returned to the basal levels following chronic homotypic stress. In contrast, oxytocin mRNA expression was significantly increased following chronic homotypic stress. The number of oxytocin-immunoreactive cells was increased following chronic homotypic stress at the magnocellular part of the PVN. Icv injection of oxytocin reduced CRF mRNA expression induced by acute stress and chronic heterotypic stress. It is suggested that the adaptation mechanism to chronic stress may involve the upregulation of oxytocin expression in the hypothalamus, which in turn attenuates CRF expression. PMID:20689056

  10. Benzoxazinone-Mediated Triazine Degradation: A Proposed Reaction Mechanism.

    PubMed

    Willett, C D; Lerch, R N; Lin, C-H; Goyne, K W; Leigh, N D; Roberts, C A

    2016-06-22

    The role of benzoxazinones (Bx, 2-hydroxy-2H-1,4-benzoxazin-3(4H)-one) in triazine resistance in plants has been studied for over half a century. In this research, fundamental parameters of the reaction between DIBOA-Glc (2-β-d-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one) and atrazine (ATR, 6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine) were examined. Through a series of experiments employing a variety of chromatographic and spectroscopic techniques, the DIBOA-Glc/ATR reaction was characterized in terms of reactant and product kinetics, stoichiometry, identification of a reaction intermediate, and reaction products formed. Results of these experiments demonstrated that the reaction mechanism proceeds via nucleophilic attack of the hydroxamic acid moiety of DIBOA-Glc at the C-2 position of the triazine ring to form hydroxyatrazine (HA, 2-hydroxy-4-ethylamino-6-isopropylamino-s-triazine), with associated degradation of DIBOA-Glc. Degradation of reactants followed first-order kinetics with a noncatalytic role of DIBOA-Glc. A reaction intermediate was identified as a DIBOA-Glc-HA conjugate, indicating a 1:1 DIBOA-Glc:ATR stoichiometry. Reaction products included HA and Cl(-), but definitive identification of DIBOA-Glc reaction product(s) was not attained. With these reaction parameters elucidated, DIBOA-Glc can be evaluated in terms of its potential for a myriad of applications, including its use to address the problem of widespread ATR contamination of soil and water resources. PMID:27215133

  11. The mechanism of OTUB1-mediated inhibition of ubiquitination

    SciTech Connect

    Wiener, Reuven; Zhang, Xiangbin; Wang, Tao; Wolberger, Cynthia

    2013-04-08

    Histones are ubiquitinated in response to DNA double-strand breaks (DSB), promoting recruitment of repair proteins to chromatin. UBC13 (also known as UBE2N) is a ubiquitin-conjugating enzyme (E2) that heterodimerizes with UEV1A (also known as UBE2V1) and synthesizes K63-linked polyubiquitin (K63Ub) chains at DSB sites in concert with the ubiquitin ligase (E3), RNF168 (ref. 3). K63Ub synthesis is regulated in a non-canonical manner by the deubiquitinating enzyme, OTUB1 (OTU domain-containing ubiquitin aldehyde-binding protein 1), which binds preferentially to the UBC13-Ub thiolester. Residues amino-terminal to the OTU domain, which had been implicated in ubiquitin binding, are required for binding to UBC13-Ub and inhibition of K63Ub synthesis. Here we describe structural and biochemical studies elucidating how OTUB1 inhibits UBC13 and other E2 enzymes. We unexpectedly find that OTUB1 binding to UBC13-Ub is allosterically regulated by free ubiquitin, which binds to a second site in OTUB1 and increases its affinity for UBC13-Ub, while at the same time disrupting interactions with UEV1A in a manner that depends on the OTUB1 N terminus. Crystal structures of an OTUB1-UBC13 complex and of OTUB1 bound to ubiquitin aldehyde and a chemical UBC13-Ub conjugate show that binding of free ubiquitin to OTUB1 triggers conformational changes in the OTU domain and formation of a ubiquitin-binding helix in the N terminus, thus promoting binding of the conjugated donor ubiquitin in UBC13-Ub to OTUB1. The donor ubiquitin thus cannot interact with the E2 enzyme, which has been shown to be important for ubiquitin transfer. The N-terminal helix of OTUB1 is positioned to interfere with UEV1A binding to UBC13, as well as with attack on the thiolester by an acceptor ubiquitin, thereby inhibiting K63Ub synthesis. OTUB1 binding also occludes the RING E3 binding site on UBC13, thus providing a further component of inhibition. The general features of the inhibition mechanism explain how OTUB1

  12. Ca2+-Dependent Endoplasmic Reticulum Stress Regulates Mechanical Stress-Mediated Cartilage Thinning.

    PubMed

    Zhu, M; Zhou, S; Huang, Z; Wen, J; Li, H

    2016-07-01

    Our previous study identified that endoplasmic reticulum stress (ERS) plays a critical role in chondrocyte apoptosis and mandibular cartilage thinning in response to compressive mechanical force, although the underlying mechanisms remain elusive. Because the endoplasmic reticulum (ER) is a primary site of intracellular Ca(2+) storage, we hypothesized that Ca(2+)-dependent ERS might be involved in mechanical stress-mediated mandibular cartilage thinning. In this study, we used in vitro and in vivo models to determine Ca(2+) concentrations, histological changes, subcellular changes, apoptosis, and the expression of ERS markers in mandibular cartilage and chondrocytes. The results showed that in chondrocytes, cytosolic Ca(2+) ([Ca(2+)]i) was dramatically increased by compressive mechanical force. Interestingly, the inhibition of Ca(2+) channels by ryanodine and 2-aminoethoxydiphenyl borate, inhibitors of ryanodine receptors and inositol trisphosphate receptors, respectively, partially rescued mechanical force-mediated mandibular cartilage thinning. Furthermore, chondrocyte apoptosis was also compromised by inhibiting the increase in [Ca(2+)]i that occurred in response to compressive mechanical force. Mechanistically, the ERS induced by compressive mechanical force was also repressed by [Ca(2+)]i inhibition, as demonstrated by a decrease in the expression of the ER stress markers 78 kDa glucose-regulated protein (GRP78) and 94 kDa glucose-regulated protein (GRP94) at both the mRNA and protein levels. Collectively, these data identified [Ca(2+)]i as a critical mediator of the pathological changes that occur in mandibular cartilage under compressive mechanical force and shed light on the treatment of mechanical stress-mediated cartilage degradation. PMID:27053115

  13. Vinpocetine Reduces Carrageenan-Induced Inflammatory Hyperalgesia in Mice by Inhibiting Oxidative Stress, Cytokine Production and NF-κB Activation in the Paw and Spinal Cord

    PubMed Central

    Ruiz-Miyazawa, Kenji W.; Zarpelon, Ana C.; Pinho-Ribeiro, Felipe A.; Pavão-de-Souza, Gabriela F.; Casagrande, Rubia; Verri, Waldiceu A.

    2015-01-01

    Vinpocetine is a safe nootropic agent used for neurological and cerebrovascular diseases. The anti-inflammatory activity of vinpocetine has been shown in cell based assays and animal models, leading to suggestions as to its utility in analgesia. However, the mechanisms regarding its efficacy in inflammatory pain treatment are still not completely understood. Herein, the analgesic effect of vinpocetine and its anti-inflammatory and antioxidant mechanisms were addressed in murine inflammatory pain models. Firstly, we investigated the protective effects of vinpocetine in overt pain-like behavior induced by acetic acid, phenyl-p-benzoquinone (PBQ) and formalin. The intraplantar injection of carrageenan was then used to induce inflammatory hyperalgesia. Mechanical and thermal hyperalgesia were evaluated using the electronic von Frey and the hot plate tests, respectively, with neutrophil recruitment to the paw assessed by a myeloperoxidase activity assay. A number of factors were assessed, both peripherally and in the spinal cord, including: antioxidant capacity, reduced glutathione (GSH) levels, superoxide anion, tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β) levels, as well as nuclear factor kappa B (NF-κB) activation. Vinpocetine inhibited the overt pain-like behavior induced by acetic acid, PBQ and formalin (at both phases), as well as the carrageenan-induced mechanical and thermal hyperalgesia and associated neutrophil recruitment. Both peripherally and in the spinal cord, vinpocetine also inhibited: antioxidant capacity and GSH depletion; increased superoxide anion; IL-1β and TNF-α levels; and NF-κB activation. As such, vinpocetine significantly reduces inflammatory pain by targeting oxidative stress, cytokine production and NF-κB activation at both peripheral and spinal cord levels. PMID:25822523

  14. Vinpocetine reduces carrageenan-induced inflammatory hyperalgesia in mice by inhibiting oxidative stress, cytokine production and NF-κB activation in the paw and spinal cord.

    PubMed

    Ruiz-Miyazawa, Kenji W; Zarpelon, Ana C; Pinho-Ribeiro, Felipe A; Pavão-de-Souza, Gabriela F; Casagrande, Rubia; Verri, Waldiceu A

    2015-01-01

    Vinpocetine is a safe nootropic agent used for neurological and cerebrovascular diseases. The anti-inflammatory activity of vinpocetine has been shown in cell based assays and animal models, leading to suggestions as to its utility in analgesia. However, the mechanisms regarding its efficacy in inflammatory pain treatment are still not completely understood. Herein, the analgesic effect of vinpocetine and its anti-inflammatory and antioxidant mechanisms were addressed in murine inflammatory pain models. Firstly, we investigated the protective effects of vinpocetine in overt pain-like behavior induced by acetic acid, phenyl-p-benzoquinone (PBQ) and formalin. The intraplantar injection of carrageenan was then used to induce inflammatory hyperalgesia. Mechanical and thermal hyperalgesia were evaluated using the electronic von Frey and the hot plate tests, respectively, with neutrophil recruitment to the paw assessed by a myeloperoxidase activity assay. A number of factors were assessed, both peripherally and in the spinal cord, including: antioxidant capacity, reduced glutathione (GSH) levels, superoxide anion, tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β) levels, as well as nuclear factor kappa B (NF-κB) activation. Vinpocetine inhibited the overt pain-like behavior induced by acetic acid, PBQ and formalin (at both phases), as well as the carrageenan-induced mechanical and thermal hyperalgesia and associated neutrophil recruitment. Both peripherally and in the spinal cord, vinpocetine also inhibited: antioxidant capacity and GSH depletion; increased superoxide anion; IL-1β and TNF-α levels; and NF-κB activation. As such, vinpocetine significantly reduces inflammatory pain by targeting oxidative stress, cytokine production and NF-κB activation at both peripheral and spinal cord levels. PMID:25822523

  15. Thermal hyperalgesia and light touch allodynia after intradermal Mycobacterium butyricum administration in rat.

    PubMed

    Arévalo, Maria Isabel; Escribano, Elvira; Calpena, Ana; Domenech, Josep; Queralt, Josep

    2003-10-01

    We examined the time course (7 weeks) of thermal hyperalgesia and light touch allodynia in rats after intradermal administration of Mycobacterium butyricum. Nociceptive thresholds to heat and light touch were assessed. Paw edema and temperature, motor function, body weight, and propioception were also tested. Some rats developed arthritis (named AA rats) but others did not (named non-AA rats). Both groups were compared with healthy animals. Persistent hyperalgesia was found in both groups; in AA rats it appeared before clinical evidence of arthritis. Transient allodynia ocurred only after edema development and fell when edema decreased. Motor function was impaired only in AA rats. The results of this study demonstrate that hyperalgesia, but not allodynia, appeared after Mycobacterium butyricum in both groups, suggesting that changes in sensitivity were not merely the result of local hypersensitivity of the inflamed tissue, but may also be due to alterations in nociception in the central nervous system. PMID:14635786

  16. Mediating Mechanisms for the Intergenerational Transmission of Constructive Parenting: A Prospective Longitudinal Study

    PubMed Central

    Chen, Zeng-yin; Liu, Ruth X.; Kaplan, Howard B.

    2010-01-01

    Based on a prospective longitudinal panel data set that was collected at three developmental stages—early adolescence, young adulthood, and middle adulthood— this study investigates marital satisfaction and educational attainment as mediating mechanisms as well as gender's moderating effect for the intergenerational transmission of constructive parenting (N = 1,560). The results show that perceived satisfying experiences with parents during early adolescence are positively related to marital satisfaction and educational attainment in young adulthood, which, in turn, are positively related to individuals' utilization of constructive parenting in middle adulthood. The two mediating mechanisms account for most of the direct effect of the intergenerational transmission of constructive parenting. Furthermore, the mediating effect of marital relationship is stronger for current fathers than for mothers because of a stronger association between marital satisfaction and constructive parenting for men. The implications are discussed. PMID:20357901

  17. Evaluation of heat hyperalgesia and anxiety like-behaviors in a rat model of orofacial cancer.

    PubMed

    Gambeta, Eder; Kopruszinski, Caroline Machado; Dos Reis, Renata Cristiane; Zanoveli, Janaina Menezes; Chichorro, Juliana Geremias

    2016-04-21

    Pain and anxiety are commonly experienced by cancer patients and both significantly impair their quality of life. Some authors claim that there is a relationship between pain and anxiety, while others suggest that there is not a direct association. In any case, there is indeed a consensus that anxiety impairs the pain condition beyond be under diagnosed and undertreated in cancer pain patients. Herein we investigated if rats presenting heat hyperalgesia induced by orofacial cancer cell inoculation would display anxiety-like behaviors. In addition, we evaluated if pain blockade would result in alleviation of anxiety behaviors, as well as, if blockade of anxiety would result in pain relief. Orofacial cancer was induced in male Wistar rats by inoculation of Walker-256 cells into the right vibrissal pad. Heat facial hyperalgesia was assessed on day 6 after the inoculation, and on this time point rats were submitted to the elevated plus maze and the light-dark transition tests. The influence of lidocaine and midazolam on heat hyperalgesia and anxiety-like behaviors was assessed. The peak of facial heat hyperalgesia was detected 6 days after cancer cells inoculation, and at this time point, rats exhibited increased anxiety-like behaviors. Local treatment with lidocaine (2%/50μL) caused a marked reduction of heat hyperalgesia, but failed to affect the anxiety-like behaviors, while midazolam (0.5mg/kg, i.p.) treatment failed to change the heat threshold, but induced an anxiolytic-like effect. Altogether, our data demonstrated that rats with orofacial cancer present pain- and anxiety-like behaviors, but brief heat hyperalgesia relief does not affect the anxiety-like behaviors, and vice-versa, in our experimental conditions. PMID:26952973

  18. The Mediated MIMIC Model for Understanding the Underlying Mechanism of DIF

    ERIC Educational Resources Information Center

    Cheng, Ying; Shao, Can; Lathrop, Quinn N.

    2016-01-01

    Due to its flexibility, the multiple-indicator, multiple-causes (MIMIC) model has become an increasingly popular method for the detection of differential item functioning (DIF). In this article, we propose the mediated MIMIC model method to uncover the underlying mechanism of DIF. This method extends the usual MIMIC model by including one variable…

  19. Mediating Mechanisms for the Intergenerational Transmission of Constructive Parenting: A Prospective Longitudinal Study

    ERIC Educational Resources Information Center

    Chen, Zeng-yin; Liu, Ruth X.; Kaplan, Howard B.

    2008-01-01

    Based on a prospective longitudinal panel data set that was collected at three developmental stages--early adolescence, young adulthood, and middle adulthood--this study investigates marital satisfaction and educational attainment as mediating mechanisms as well as gender's moderating effect for the intergenerational transmission of constructive…

  20. Mother-Child Attachment and Cognitive Performance in Middle Childhood: An Examination of Mediating Mechanisms

    ERIC Educational Resources Information Center

    West, Katara K.; Mathews, Brittany L.; Kerns, Kathryn A.

    2013-01-01

    Although mother-child attachment has been shown to predict cognitive performance, there has been a lack of attention to the mediating mechanisms that explain these associations. In the present study, we investigated relations of early mother-child attachment and cognitive performance in middle childhood (the latter in terms of both academic…

  1. Rheological and mechanical properties of polyamide 6 modified by electron-beam initiated mediation process

    NASA Astrophysics Data System (ADS)

    Shin, Boo Young; Kim, Jae Hong

    2015-07-01

    Polyamide (PA6) has been modified by electron-beam initiated mediator process to improve drawbacks of PA6. Glycidyl methacrylate (GMA) was chosen as a reactive mediator for modification process of PA6. The mixture of the PA6 and GMA was prepared by using a twin-screw extruder, and then the mixture was exposed to electron-beam irradiation at various doses at room temperature. The modified PA6 were characterized by observing rheological and mechanical properties and compared virgin PA6. Thermal properties, water absorption, and gel fraction were also investigated. Tight gel was not found even when PA6 was irradiated at 200 kGy. Complex viscosity and storage modulus of PA6 were remarkably increased by electron-beam irradiation with medium of GMA. Maximum increase in complex viscosity was 75 times higher than virgin PA6 at 0.1 rad/s when it was irradiated at 200 kGy with the GMA. Mechanical properties were also improved without scarifying of processability. The reaction mechanisms for the mediation process with the reactive mediator of GMA were estimated to elucidate the cause of significantly enhanced rheological and mechanical properties without loss of thermoplasticity.

  2. Microwave-Mediated Synthesis of Lophine: Developing a Mechanism to Explain a Product

    ERIC Educational Resources Information Center

    Crouch, R. David; Howard, Jessica L.; Zile, Jennifer L.; Barker, Kathryn H.

    2006-01-01

    The microwave-mediated preparation of lophine (2,4,5-triphenylimidazole) is described. This experiment allows for an introduction to the emerging technology of microwave-assisted organic synthesis while providing an opportunity for students to employ the principles of carbonyl chemistry in devising a mechanism to explain the formation of the…

  3. Controlling Stem Cell-mediated Bone Regeneration through Tailored Mechanical Properties of Collagen Scaffolds

    PubMed Central

    Sun, Hongli; Zhu, Feng; Hu, Qingang; Krebsbach, Paul H.

    2014-01-01

    Mechanical properties of the extracellular matrix (ECM) play an essential role in cell fate determination. To study the role of mechanical properties of ECM in stem cell-mediated bone regeneration, we used a 3D in vivo ossicle model that recapitulates endochondral bone formation. Three-dimensional gelatin scaffolds with distinct stiffness were developed using 1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) mediated zero-length crosslinking. The mechanical strength of the scaffolds was significantly increased by EDC treatment, while the microstructure of the scaffold was preserved. Cell behavior on the scaffolds with different mechanical properties was evaluated in vitro and in vivo. EDC-treated scaffolds promoted early chondrogenic differentiation, while it promoted both chondrogenic and osteogenic differentiation at later time points. Both micro-computed tomography and histologic data demonstrated that EDC-treatment significantly increased trabecular bone formation by transplanted cells transduced with AdBMP. Moreover, significantly increased chondrogenesis was observed in the EDC-treated scaffolds. Based on both in vitro and in vivo data, we conclude that the high mechanical strength of 3D scaffolds promoted stem cell mediated bone regeneration by promoting endochondral ossification. These data suggest a new method for harnessing stem cells for bone regeneration in vivo by tailoring the mechanical properties of 3D scaffolds. PMID:24211076

  4. Mechanisms of Biased β-Arrestin-Mediated Signaling Downstream from the Cannabinoid 1 Receptor

    PubMed Central

    Delgado-Peraza, Francheska; Ahn, Kwang H.; Nogueras-Ortiz, Carlos; Mungrue, Imran N.; Mackie, Ken; Kendall, Debra A.

    2016-01-01

    Activation of G protein-coupled receptors results in multiple waves of signaling that are mediated by heterotrimeric G proteins and the scaffolding proteins β-arrestin 1/2. Ligands can elicit full or subsets of cellular responses, a concept defined as ligand bias or functional selectivity. However, our current understanding of β-arrestin-mediated signaling is still very limited. Here we provide a comprehensive view of β-arrestin-mediated signaling from the cannabinoid 1 receptor (CB1R). By using a signaling biased receptor, we define the cascades, specific receptor kinases, and molecular mechanism underlying β-arrestin-mediated signaling: We identify the interaction kinetics of CB1R and β-arrestin 1 during their endocytic trafficking as directly proportional to its efficacy. Finally, we demonstrate that signaling results in the control of genes clustered around prosurvival and proapoptotic functions among others. Together, these studies constitute a comprehensive description of β-arrestin-mediated signaling from CB1Rs and suggest modulation of receptor endocytic trafficking as a therapeutic approach to control β-arrestin-mediated signaling. PMID:27009233

  5. Mechanisms of Biased β-Arrestin-Mediated Signaling Downstream from the Cannabinoid 1 Receptor.

    PubMed

    Delgado-Peraza, Francheska; Ahn, Kwang H; Nogueras-Ortiz, Carlos; Mungrue, Imran N; Mackie, Ken; Kendall, Debra A; Yudowski, Guillermo A

    2016-06-01

    Activation of G protein-coupled receptors results in multiple waves of signaling that are mediated by heterotrimeric G proteins and the scaffolding proteins β-arrestin 1/2. Ligands can elicit full or subsets of cellular responses, a concept defined as ligand bias or functional selectivity. However, our current understanding of β-arrestin-mediated signaling is still very limited. Here we provide a comprehensive view of β-arrestin-mediated signaling from the cannabinoid 1 receptor (CB1R). By using a signaling biased receptor, we define the cascades, specific receptor kinases, and molecular mechanism underlying β-arrestin-mediated signaling: We identify the interaction kinetics of CB1R and β-arrestin 1 during their endocytic trafficking as directly proportional to its efficacy. Finally, we demonstrate that signaling results in the control of genes clustered around prosurvival and proapoptotic functions among others. Together, these studies constitute a comprehensive description of β-arrestin-mediated signaling from CB1Rs and suggest modulation of receptor endocytic trafficking as a therapeutic approach to control β-arrestin-mediated signaling. PMID:27009233

  6. Abundant Genetic Overlap between Blood Lipids and Immune-Mediated Diseases Indicates Shared Molecular Genetic Mechanisms

    PubMed Central

    Andreassen, Ole A.; Desikan, Rahul S.; Wang, Yunpeng; Thompson, Wesley K.; Schork, Andrew J.; Zuber, Verena; Doncheva, Nadezhda T.; Ellinghaus, Eva; Albrecht, Mario; Mattingsdal, Morten; Franke, Andre; Lie, Benedicte A.; Mills, Ian; Aukrust, Pål; McEvoy, Linda K.; Djurovic, Srdjan; Karlsen, Tom H.; Dale, Anders M.

    2015-01-01

    Epidemiological studies suggest a relationship between blood lipids and immune-mediated diseases, but the nature of these associations is not well understood. We used genome-wide association studies (GWAS) to investigate shared single nucleotide polymorphisms (SNPs) between blood lipids and immune-mediated diseases. We analyzed data from GWAS (n~200,000 individuals), applying new False Discovery Rate (FDR) methods, to investigate genetic overlap between blood lipid levels [triglycerides (TG), low density lipoproteins (LDL), high density lipoproteins (HDL)] and a selection of archetypal immune-mediated diseases (Crohn’s disease, ulcerative colitis, rheumatoid arthritis, type 1 diabetes, celiac disease, psoriasis and sarcoidosis). We found significant polygenic pleiotropy between the blood lipids and all the investigated immune-mediated diseases. We discovered several shared risk loci between the immune-mediated diseases and TG (n = 88), LDL (n = 87) and HDL (n = 52). Three-way analyses differentiated the pattern of pleiotropy among the immune-mediated diseases. The new pleiotropic loci increased the number of functional gene network nodes representing blood lipid loci by 40%. Pathway analyses implicated several novel shared mechanisms for immune pathogenesis and lipid biology, including glycosphingolipid synthesis (e.g. FUT2) and intestinal host-microbe interactions (e.g. ATG16L1). We demonstrate a shared genetic basis for blood lipids and immune-mediated diseases independent of environmental factors. Our findings provide novel mechanistic insights into dyslipidemia and immune-mediated diseases and may have implications for therapeutic trials involving lipid-lowering and anti-inflammatory agents. PMID:25853426

  7. Sensitization of neonatal rat lumbar motoneuron by the inflammatory pain mediator bradykinin

    PubMed Central

    Bouhadfane, Mouloud; Kaszás, Attila; Rózsa, Balázs; Harris-Warrick, Ronald M; Vinay, Laurent; Brocard, Frédéric

    2015-01-01

    Bradykinin (Bk) is a potent inflammatory mediator that causes hyperalgesia. The action of Bk on the sensory system is well documented but its effects on motoneurons, the final pathway of the motor system, are unknown. By a combination of patch-clamp recordings and two-photon calcium imaging, we found that Bk strongly sensitizes spinal motoneurons. Sensitization was characterized by an increased ability to generate self-sustained spiking in response to excitatory inputs. Our pharmacological study described a dual ionic mechanism to sensitize motoneurons, including inhibition of a barium-sensitive resting K+ conductance and activation of a nonselective cationic conductance primarily mediated by Na+. Examination of the upstream signaling pathways provided evidence for postsynaptic activation of B2 receptors, G protein activation of phospholipase C, InsP3 synthesis, and calmodulin activation. This study questions the influence of motoneurons in the assessment of hyperalgesia since the withdrawal motor reflex is commonly used as a surrogate pain model. DOI: http://dx.doi.org/10.7554/eLife.06195.001 PMID:25781633

  8. The Relation of Perceived Neighborhood Danger to Childhood Aggression: A Test of Mediating Mechanisms1

    PubMed Central

    Colder, Craig R.; Mott, Joshua; Levy, Susan; Flay, Brian

    2008-01-01

    In the current study, two mediational mechanisms, parenting practices and children’s beliefs about aggression, were hypothesized to account for the relationship between perceived neighborhood danger and childhood aggression. Using structural equation modeling, data were analyzed from an inner-city school-based sample of 732 predominantly African American 5th graders. Results suggested that perceived neighborhood danger was associated with strong positive beliefs about aggression, which in turn was associated with high levels of aggression. The hypothesized mediating role of parenting practices (restrictive discipline, parental monitoring, and parental involvement) on the relation between perceived neighborhood danger and child aggression was not supported. However, the current findings suggest that children’s positive beliefs about aggression mediated the relationship between restrictive discipline and aggression. Directions for future research are discussed. PMID:10824275

  9. Antennae in the hawkmoth Manduca sexta (Lepidoptera, Sphingidae) mediate abdominal flexion in response to mechanical stimuli.

    PubMed

    Hinterwirth, Armin J; Daniel, Thomas L

    2010-12-01

    Flying insects rely on the integration of feedback signals from multiple sensory modalities. Thus, in addition to the visual input, mechanosensory information from antennae is crucial for stable flight in the hawkmoth Manduca sexta. However, the nature of compensatory reflexes mediated by mechanoreceptors on the antennae is unknown. In this study we describe an abdominal flexion response mediated by the antennal mechanosensory input during mechanical body rotations. Such reflexive abdominal motions lead to shifts in the animal's center of mass, and therefore changes in flight trajectory. Moths respond with abdominal flexion both to visual and mechanical rotations, but the mechanical response depends on the presence of the mass of the flagellum. In addition, the mechanically mediated flexion response is about 200° out of phase with the visual response and adds linearly to it. Phase-shifting feedback signals in such a manner can lead to a more stable behavioral output response when the animal is faced with turbulent perturbations to the flight path. PMID:20820787

  10. Potential mechanisms mediating improved glycemic control after bariatric/metabolic surgery.

    PubMed

    Yamamoto, Hiroshi; Kaida, Sachiko; Yamaguchi, Tsuyoshi; Murata, Satoshi; Tani, Masaji; Tani, Tohru

    2016-03-01

    Conservative medical treatment for morbid obesity generally fails to sustain weight loss. On the other hand, surgical operations, so-called bariatric surgery, have evolved due to their long-term effects. The global increase in the overweight population and the introduction of laparoscopic surgery have resulted in the use of bariatric surgery spreading quickly worldwide in recent years. Recent clinical evidence suggests that bariatric surgery not only reduces body weight, but also improves secondary serious diseases, including type 2 diabetes mellitus, in so-called metabolic surgery. Moreover, several potential mechanisms mediating the improvement in glycemic control after bariatric/metabolic surgery have been proposed based on the animal and human studies. These mechanisms include changes in the levels of gastrointestinal hormones, bacterial flora, bile acids, intestinal gluconeogenesis and gastrointestinal motility as well as adipose tissue and inflammatory mediators after surgery. The mechanisms underlying improved glycemic control are expected to accelerate the promotion of both metabolic and bariatric surgery. This article describes the current status of bariatric surgery worldwide and in Japan, reviews the accumulated data for weight loss and diabetic improvements after surgery and discusses the potential mechanisms mediating improved glycemic control. PMID:25700844

  11. ATP in human skin elicits a dose-related pain response which is potentiated under conditions of hyperalgesia.

    PubMed

    Hamilton, S G; Warburton, J; Bhattacharjee, A; Ward, J; McMahon, S B

    2000-06-01

    Despite the considerable interest in the possibility that ATP may function as a peripheral pain mediator, there has been little quantitative study of the pain-producing effects of ATP in humans. Here we have used iontophoresis to deliver ATP to the forearm skin of volunteers who rated the magnitude of the evoked pain on a visual analogue scale. ATP consistently produced a modest burning pain, which began within 20 s of starting iontophoresis and was maintained for several minutes. Persistent iontophoresis of ATP led to desensitization within 12 min but recovery from this was almost complete 1 h later. Different doses of ATP were delivered using different iontophoretic driving currents. Iontophoresis of ATP produced a higher pain rating than saline, indicating that the pain was specifically caused by ATP. The average pain rating for ATP, but not saline, increased with increasing current. Using an 0.8 mA current, subjects reported pain averaging 27.7 +/- 2.8 (maximum possible = 100). Iontophoresis of ATP caused an increase in blood flow, as assessed using a laser Doppler flow meter. The increase in blood flow was significantly greater using ATP than saline in both the iontophoresed skin (P < 0.01) and in the surrounding skin, 3 mm outside the iontophoresed area (P < 0.05). The pain produced by ATP was dependent on capsaicin-sensitive sensory neurons, since in skin treated repeatedly with topical capsaicin pain was reduced to less than 25% of that elicited on normal skin (2.1 +/- 0.4 compared with 9.3 +/- 1.5 on normal skin). Conversely, the pain-producing effects of ATP were greatly potentiated in several models of hyperalgesia. Thus, with acute capsaicin treatment when subjects exhibited touch-evoked hyperalgesia but no ongoing pain, there was a threefold increase in the average pain rating during ATP iontophoresis (22.7 +/- 3.1) compared with pre-capsaicin treatment (7.8 +/- 2.6). Moreover, ATP iontophoresed into skin 24 h after solar simulated radiation (2 x

  12. ATR mediates a checkpoint at the nuclear envelope in response to mechanical stress.

    PubMed

    Kumar, Amit; Mazzanti, Michele; Mistrik, Martin; Kosar, Martin; Beznoussenko, Galina V; Mironov, Alexandre A; Garrè, Massimiliano; Parazzoli, Dario; Shivashankar, G V; Scita, Giorgio; Bartek, Jiri; Foiani, Marco

    2014-07-31

    ATR controls chromosome integrity and chromatin dynamics. We have previously shown that yeast Mec1/ATR promotes chromatin detachment from the nuclear envelope to counteract aberrant topological transitions during DNA replication. Here, we provide evidence that ATR activity at the nuclear envelope responds to mechanical stress. Human ATR associates with the nuclear envelope during S phase and prophase, and both osmotic stress and mechanical stretching relocalize ATR to nuclear membranes throughout the cell cycle. The ATR-mediated mechanical response occurs within the range of physiological forces, is reversible, and is independent of DNA damage signaling. ATR-defective cells exhibit aberrant chromatin condensation and nuclear envelope breakdown. We propose that mechanical forces derived from chromosome dynamics and torsional stress on nuclear membranes activate ATR to modulate nuclear envelope plasticity and chromatin association to the nuclear envelope, thus enabling cells to cope with the mechanical strain imposed by these molecular processes. PMID:25083873

  13. Evaluation of Dynamic Weight Bearing for Measuring Nonevoked Inflammatory Hyperalgesia in Mice

    PubMed Central

    Griffioen, Mari A.; Dernetz, Valerie H.; Yang, Gee Su; Griffith, Kathleen A.; Dorsey, Susan G.; Renn, Cynthia L.

    2014-01-01

    Background Animal models in pain research have suggested that inclusion of both evoked and nonevoked behavioral measures are needed to better reflect the human pain experience. Individuals with chronic pain are known to experience spontaneous pain, in addition to pain, following exposure to an external stimulus. Recently, the Dynamic Weight Bearing (DWB) apparatus was developed to assess for nonevoked hyperalgesia by capturing weight bearing and surface distribution in the paws of mice following acute inflammation. Objectives The aim of this study was to evaluate the DWB test as a measure of nonevoked hyperalgesia. Method The experimental group received an intraplantar injection to the left hind paw of the inflammatory agent—Complete Freund's Adjuvant (CFA)—while the vehicle control group received a saline injection, and the naïve control group had no treatment. Caliper and plethysmometer were used to verify inflammation, and the hot-plate test was used as a measure for stimulus evoked hyperalgesia. Data were collected at baseline, three hours, one, three, and seven days after injection. Results Mice injected with CFA showed a statistically significant higher mean paw thickness and volume displacement compared to vehicle and naïve control groups. In the hot-plate testing, CFA-treated mice showed lower response temperature at seven days compared to other groups. On the DWB test, CFA-treated mice showed a reduction in the ipsilateral paw load and surface area compared to the contralateral paw load at Day 1, Day 3 and Day 7. Discussion Mice with inflammation demonstrated alterations in weight bearing, as well as increased thermal hyperalgesia in comparison to controls groups. These findings support the use of the DWB test as a tool for measuring nonevoked inflammatory hyperalgesia in a mouse model. PMID:25738619

  14. The mechanism of neutral red-mediated microbial electrosynthesis in Escherichia coli: menaquinone reduction.

    PubMed

    Harrington, Timothy D; Tran, Vi N; Mohamed, Abdelrhman; Renslow, Ryan; Biria, Saeid; Orfe, Lisa; Call, Douglas R; Beyenal, Haluk

    2015-09-01

    The aim of this work was to elucidate the mechanism of mediated microbial electrosynthesis via neutral red from an electrode to fermenting Escherichia coli cultures in a bioelectrochemical system. Chemical reduction of NAD(+) by reduced neutral red did not occur as predicted. Instead, neutral red was shown to reduce the menaquinone pool in the inner bacterial membrane. The reduced menaquinone pool altered fermentative metabolite production via the arcB redox-sensing cascade in the absence of terminal electron acceptors. When the acceptors DMSO, fumarate, or nitrate were provided, as many as 19% of the electrons trapped in the reduced acceptors were derived from the electrode. These results demonstrate the mechanism of neutral red-mediated microbial electrosynthesis during fermentation as well as how neutral red enables microbial electrosynthesis of reduced terminal electron acceptors. PMID:26094195

  15. The effect of corporal punishment and verbal abuse on delinquency: mediating mechanisms.

    PubMed

    Evans, Sara Z; Simons, Leslie Gordon; Simons, Ronald L

    2012-08-01

    While the link between parenting and delinquency is well established, there is less consensus among scholars with regards to the processes that account for this link. The current study had two objectives. The first was to disentangle the effects of African American parents' use of corporal punishment and verbal abuse on the conduct problems of their preteen children. The second was to investigate the mechanisms that explain this relationship, such as having low self-control or a hostile view of relationships, whereby these harsh parenting practices increase a youth's involvement in problem behavior. Further, we are interested in specifically addressing how these mechanisms may operate differently for males versus females. Analyses utilized structural equation modeling and longitudinal data spanning approximately 2.5 years from a sample of 704 (54.2 % female) African American children ages 10-12. The results indicated that verbal abuse was a more important predictor of conduct problems than corporal punishment. Additionally, we found that the mechanisms that mediated the impact of verbal abuse and corporal punishment on conduct problems varied by gender. For males, most of the effect of verbal abuse was mediated by low self-control, whereas anger/frustration was the primary mediator for females. Implications of these results and directions for future study are also discussed. PMID:22460730

  16. Blockade of peripheral P2Y1 receptors prevents the induction of thermal hyperalgesia via modulation of TRPV1 expression in carrageenan-induced inflammatory pain rats: involvement of p38 MAPK phosphorylation in DRGs.

    PubMed

    Kwon, Soon-Gu; Roh, Dae-Hyun; Yoon, Seo-Yeon; Moon, Ji-Young; Choi, Sheu-Ran; Choi, Hoon-Seong; Kang, Suk-Yun; Han, Ho-Jae; Beitz, Alvin J; Lee, Jang-Hern

    2014-04-01

    Although previous reports have suggested that P2Y1 receptors (P2Y1Rs) are involved in cutaneous nociceptive signaling, it remains unclear how P2Y1Rs contribute to peripheral sensitization. The current study was designed to delineate the role of peripheral P2Y1Rs in pain and to investigate potential linkages to mitogen-activated protein kinase (MAPK) in DRGs and Transient Receptor Potential Vanilloid 1 (TRPV1) expression in a rodent inflammatory pain model. Following injection of 2% carrageenan into the hind paw, expressions of P2Y1 and TRPV1 and the phosphorylation rates of both p38 MAPK and ERK but not JNK were increased and peaked at day 2 post-injection. Blockade of peripheral P2Y1Rs by the P2Y1R antagonist, MRS2500 injection (i.pl, D0 to D2) significantly reduced the induction of thermal hyperalgesia, but not mechanical allodynia. Simultaneously, MRS2500 injections suppressed upregulated TRPV1 expression and DRG p38 phosphorylation, while pERK signaling was not affected. Furthermore, inhibition of p38 activation in the DRGs by SB203580 (a p38 inhibitor, i.t, D0 to D2) prevented the upregulation of TRPV1 and a single i.t injection of SB203580 reversed the established thermal hyperalgesia, but not mechanical allodynia. Lastly, to identify the mechanism of action of P2Y1Rs, we repeatedly injected the P2Y1 agonist, MRS2365 into the naïve rat's hind paw and observed a dose-dependent increase in TRPV1 expression and p38 MAPK phosphorylation. These data demonstrate a sequential role for P2Y1R, p38 MAPK and TRPV1 in inflammation-induced thermal hyperalgesia; thus, peripheral P2Y1Rs activation modulates p38 MAPK signaling and TRPV1 expression, which ultimately leads to the induction of thermal hyperalgesia. PMID:24333674

  17. Influence of structural load-bearing scaffolds on mechanical load- and BMP-2-mediated bone regeneration.

    PubMed

    McDermott, Anna M; Mason, Devon E; Lin, Angela S P; Guldberg, Robert E; Boerckel, Joel D

    2016-09-01

    A common design constraint in functional tissue engineering is that scaffolds intended for use in load-bearing sites possess similar mechanical properties to the replaced tissue. Here, we tested the hypothesis that in vivo loading would enhance bone morphogenetic protein-2 (BMP-2)-mediated bone regeneration in the presence of a load-bearing PLDL scaffold, whose pores and central core were filled with BMP-2-releasing alginate hydrogel. First, we evaluated the effects of in vivo mechanical loading on bone regeneration in the structural scaffolds. Second, we compared scaffold-mediated bone regeneration, independent of mechanical loading, with alginate hydrogel constructs, without the structural scaffold, that have been shown previously to facilitate in vivo mechanical stimulation of bone formation. Contrary to our hypothesis, mechanical loading had no effect on bone formation, distribution, or biomechanical properties in structural scaffolds. Independent of loading, the structural scaffolds reduced bone formation compared to non-structural alginate, particularly in regions in which the scaffold was concentrated, resulting in impaired functional regeneration. This is attributable to a combination of stress shielding by the scaffold and inhibition of cellular infiltration and tissue ingrowth. Collectively, these data question the necessity of scaffold similarity to mature tissue at the time of implantation and emphasize development of an environment conducive to cellular activation of matrix production and ultimate functional regeneration. PMID:27208510

  18. Evidence that the human cutaneous venoarteriolar response is not mediated by adrenergic mechanisms

    NASA Technical Reports Server (NTRS)

    Crandall, C. G.; Shibasaki, M.; Yen, T. C.

    2002-01-01

    The venoarteriolar response causes vasoconstriction to skin and muscle via local mechanisms secondary to venous congestion. The purpose of this project was to investigate whether this response occurs through alpha-adrenergic mechanisms. In supine individuals, forearm skin blood flow was monitored via laser-Doppler flowmetry over sites following local administration of terazosin (alpha(1)-antagonist), yohimbine (alpha(2)-antagonist), phentolamine (non-selective alpha-antagonist) and bretylium tosylate (inhibits neurotransmission of adrenergic nerves) via intradermal microdialysis or intradermal injection. In addition, skin blood flow was monitored over an area of forearm skin that was locally anaesthetized via application of EMLA (2.5 % lidocaine (lignocaine) and 2.5 % prilocaine) cream. Skin blood flow was also monitored over adjacent sites that received the vehicle for the specified drug. Each trial was performed on a minimum of seven subjects and on separate days. The venoarteriolar response was engaged by lowering the subject's arm from heart level such that the sites of skin blood flow measurement were 34 +/- 1 cm below the heart. The arm remained in this position for 2 min. Selective and non-selective alpha-adrenoceptor antagonism and presynaptic inhibition of adrenergic neurotransmission did not abolish the venoarteriolar response. However, local anaesthesia blocked the venoarteriolar response without altering alpha-adrenergic mediated vasoconstriction. These data suggest that the venoarteriolar response does not occur through adrenergic mechanisms as previously reported. Rather, the venoarteriolar response may due to myogenic mechanisms associated with changes in vascular pressure or is mediated by a non-adrenergic, but neurally mediated, local mechanism.

  19. Exercise preconditioning reduces neonatal incision surgery-induced enhanced hyperalgesia via inhibition of P38 mitogen-activated protein kinase and IL-1β, TNF-α release.

    PubMed

    Gong, Xingrui; Jiang, Jing; Zhang, Mazhong

    2016-08-01

    Neonatal surgery leads to enhanced hyperalgesia to noxious stimulation in adulthood via a mechanism caused by enhanced phosphorylated (p)-p38 expression in microglia. We tested the effect of exercise on reducing enhanced hypersensitivity primed by neonatal incision surgery. Adult female Wistar rats, with or without neonatal incision surgery at postnatal day (P) 3, received right hind paw plantar incision surgery under anesthesia at P44. The rats performed wheel-running exercise from P22 to P41. Paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were measured and ipsilateral spinal cords were collected for protein quantification. For PWT and PWL, exercise reduced the pain index after incision surgery at P44 in rats with neonatal surgery (P<0.01). Western blots showed that exercise suppressed P-p38 expression relative to adult rats without neonatal surgery (P<0.05). Results of ELISA showed that exercise reduced IL-1β and TNF-α (P<0.05) concentration in the ipsilateral spinal cord. Exercise preconditioning is an effective approach to reducing enhanced adult hyperalgesia primed by neonatal surgery. The mechanism may be explained by exercise-induced inhibition of P-p38 activation and IL-1β, TNF-α release. PMID:27235543

  20. Neural correlates of hyperalgesia in the monosodium iodoacetate model of osteoarthritis pain

    PubMed Central

    Abaei, Maryam; Sagar, Devi R; Stockley, Elizabeth G; Spicer, Clare H; Prior, Malcolm; Auer, Dorothee P

    2016-01-01

    Background The mechanisms driving osteoarthritic pain remain poorly understood, but there is increasing evidence for a role of the central nervous system in the chronification of pain. We used functional magnetic resonance imaging to investigate the influence of a model of unilateral knee osteoarthritis on nociceptive processing. Results Four to five weeks post intra-articular injection of monosodium iodoacetate (MIA, 1 mg) into the left knee, Sprague Dawley rats were anesthetized for functional magnetic resonance imaging studies to characterize the neural response to a noxious stimulus (intra-articular capsaicin injection). In a two-arm cross-over design, 5 µM/50 µl capsaicin was injected into either the left knee (n = 8, CAPS-MIA) or right control knee (n = 8, CAPS-CON), preceded by contralateral vehicle (SAL) injection. To assess neural correlates of mechanical hyperalgesia, hindpaws were stimulated with von Frey hairs (8 g: MIA; 15 g: control knee, based on behavioral withdrawal responses). The CAPS-MIA group exhibited significant activation of the periaqueductal gray, unilateral thalamus and bilateral mensencephalon, superior-colliculus, and hippocampus, with no significant activation in the other groups/conditions. Capsaicin injection increased functional connectivity in the mid-brain network and mediodorsal thalamic nucleus, hippocampus, and globus pallidus, which was significantly stronger in CAPS-MIA compared to CAPS-CON groups. Mechanical stimulation of the hyperalgesic (ipsilateral to MIA knee) and normalgesic (contralateral) hindpaws evoked qualitatively different brain activation with more widespread brainstem and anterior cingulate (ACC) activation when stimulating the hyperalgesic paw, and clearer frontal sensory activation from the normalgesic paw. Conclusions We provide evidence for modulation of nociceptive processing in a chronic knee osteoarthritis pain model with stronger brain activation and alteration of brain networks

  1. Novel mechanism of apoptosis resistance in cancer mediated by extracellular PAR-4.

    PubMed

    Burikhanov, Ravshan; Shrestha-Bhattarai, Tripti; Qiu, Shirley; Shukla, Nidhi; Hebbar, Nikhil; Lele, Subodh M; Horbinski, Craig; Rangnekar, Vivek M

    2013-01-15

    Tumor suppressor PAR-4 acts in part by modulating sensitivity to apoptosis, but the basis for its activity is not fully understood. In this study, we describe a novel mechanism of antiapoptosis by NF-κB, revealing that it can block PAR-4-mediated apoptosis by downregulating trafficking of the PAR-4 receptor GRP78 from the endoplasmic reticulum to the cell surface. Mechanistic investigations revealed that NF-κB mediated this antiapoptotic mechanism by upregulating expression of UACA, a proinflammatory protein in certain disease settings. In clinical specimens of cancer, a strong correlation existed between NF-κB activity and UACA expression, relative to normal tissues. UACA bound to intracellular PAR-4 in diverse cancer cells, where it prevented translocation of GRP78 from the endoplasmic reticulum to the cell surface. This pathway of antiapoptosis could be inhibited by suppressing levels of NF-κB or UACA expression, which enhanced endoplasmic reticulum stress and restored GRP78 trafficking to the cell surface, thereby sensitizing cancer cells to apoptosis by extracellular PAR-4 or GRP78 agonistic antibody. In summary, our results identify a novel intracellular pathway of apoptosis mediated by NF-κB through UACA elevation, which by attenuating endoplasmic reticulum stress and GRP78 translocation to the cell surface can blunt the sensitivity of cancer cells to apoptosis. PMID:23204231

  2. Chemically- and mechanically-mediated influences on the transport and mechanical characteristics of rock fractures

    SciTech Connect

    Min, K.-B.; Rutqvist, J.; Elsworth, D.

    2009-02-01

    A model is presented to represent changes in the mechanical and transport characteristics of fractured rock that result from coupled mechanical and chemical effects. The specific influence is the elevation of dissolution rates on contacting asperities, which results in a stress- and temperature-dependent permanent closure. A model representing this pressure-dissolution-like behavior is adapted to define the threshold and resulting response in terms of fundamental thermodynamic properties of a contacting fracture. These relations are incorporated in a stress-stiffening model of fracture closure to define the stress- and temperature-dependency of aperture loss and behavior during stress and temperature cycling. These models compare well with laboratory and field experiments, representing both decoupled isobaric and isothermal responses. The model was applied to explore the impact of these responses on heated structures in rock. The result showed a reduction in ultimate induced stresses over the case where chemical effects were not incorporated, with permanent reduction in final stresses after cooling to ambient conditions. Similarly, permeabilities may be lower than they were in the case where chemical effects were not considered, with a net reduction apparent even after cooling to ambient temperature. These heretofore-neglected effects may have a correspondingly significant impact on the performance of heated structures in rock, such as repositories for the containment of radioactive wastes.

  3. Investigating dynamic structural and mechanical changes of neuroblastoma cells associated with glutamate-mediated neurodegeneration

    PubMed Central

    Fang, Yuqiang; Iu, Catherine Y. Y.; Lui, Cathy N. P.; Zou, Yukai; Fung, Carmen K. M.; Li, Hung Wing; Xi, Ning; Yung, Ken K. L.; Lai, King W. C.

    2014-01-01

    Glutamate-mediated neurodegeneration resulting from excessive activation of glutamate receptors is recognized as one of the major causes of various neurological disorders such as Alzheimer's and Huntington's diseases. However, the underlying mechanisms in the neurodegenerative process remain unidentified. Here, we investigate the real-time dynamic structural and mechanical changes associated with the neurodegeneration induced by the activation of N-methyl-D-aspartate (NMDA) receptors (a subtype of glutamate receptors) at the nanoscale. Atomic force microscopy (AFM) is employed to measure the three-dimensional (3-D) topography and mechanical properties of live SH-SY5Y cells under stimulus of NMDA receptors. A significant increase in surface roughness and stiffness of the cell is observed after NMDA treatment, which indicates the time-dependent neuronal cell behavior under NMDA-mediated neurodegeneration. The present AFM based study further advance our understanding of the neurodegenerative process to elucidate the pathways and mechanisms that govern NMDA induced neurodegeneration, so as to facilitate the development of novel therapeutic strategies for neurodegenerative diseases. PMID:25399549

  4. Investigating dynamic structural and mechanical changes of neuroblastoma cells associated with glutamate-mediated neurodegeneration

    NASA Astrophysics Data System (ADS)

    Fang, Yuqiang; Iu, Catherine Y. Y.; Lui, Cathy N. P.; Zou, Yukai; Fung, Carmen K. M.; Li, Hung Wing; Xi, Ning; Yung, Ken K. L.; Lai, King W. C.

    2014-11-01

    Glutamate-mediated neurodegeneration resulting from excessive activation of glutamate receptors is recognized as one of the major causes of various neurological disorders such as Alzheimer's and Huntington's diseases. However, the underlying mechanisms in the neurodegenerative process remain unidentified. Here, we investigate the real-time dynamic structural and mechanical changes associated with the neurodegeneration induced by the activation of N-methyl-D-aspartate (NMDA) receptors (a subtype of glutamate receptors) at the nanoscale. Atomic force microscopy (AFM) is employed to measure the three-dimensional (3-D) topography and mechanical properties of live SH-SY5Y cells under stimulus of NMDA receptors. A significant increase in surface roughness and stiffness of the cell is observed after NMDA treatment, which indicates the time-dependent neuronal cell behavior under NMDA-mediated neurodegeneration. The present AFM based study further advance our understanding of the neurodegenerative process to elucidate the pathways and mechanisms that govern NMDA induced neurodegeneration, so as to facilitate the development of novel therapeutic strategies for neurodegenerative diseases.

  5. A Dystroglycan/Plectin Scaffold Mediates Mechanical Pathway Bifurcation in Lung Epithelial Cells*

    PubMed Central

    Takawira, Desire; Budinger, G. R. Scott; Hopkinson, Susan B.; Jones, Jonathan C. R.

    2011-01-01

    In alveolar epithelial cells (AECs), the membrane-anchored proteoglycan dystroglycan (DG) is a mechanoreceptor that transmits mechanical stretch forces to activate independently the ERK1/2 and the adenosine 5′-monophosphate-activated protein kinase (AMPK) signaling cascades in a process called pathway bifurcation. We tested the hypothesis that the cytoskeleton cross-linker plectin, known to bind both DG and AMPK in muscle cells, acts as a scaffold to regulate DG-mediated mechanical stimulation and pathway bifurcation. We demonstrate that plectin and DG form a complex in AECs and that this complex interacts with ERK1/2 and AMPK. Plectin knockdown reduces DG interaction with AMPK but not with ERK1/2. Despite this, mechanoactivation of both signaling pathways is significantly attenuated in AECs deficient in plectin. Thus, DG has the dual role of mechanical receptor and scaffold for ERK1/2, whereas plectin acts as a scaffold for AMPK signaling but is also required for DG-mediated ERK1/2 activation. We conclude that the DG-plectin complex plays a central role in transmitting mechanical stress from the extracellular matrix to the cytoplasm. PMID:21149456

  6. Simultaneous Inhibition of PGE2 and PGI2 Signals Is Necessary to Suppress Hyperalgesia in Rat Inflammatory Pain Models

    PubMed Central

    Kuwabara, Harumi

    2016-01-01

    Prostaglandin E2 (PGE2) is well known as a mediator of inflammatory symptoms such as fever, arthritis, and inflammatory pain. In the present study, we evaluated the analgesic effect of our selective PGE2 synthesis inhibitor, compound I, 2-methyl-2-[cis-4-([1-(6-methyl-3-phenylquinolin-2-yl)piperidin-4-yl]carbonyl amino)cyclohexyl] propanoic acid, in rat yeast-induced acute and adjuvant-induced chronic inflammatory pain models. Although this compound suppressed the synthesis of PGE2 selectively, no analgesic effect was shown in both inflammatory pain models. Prostacyclin (PGI2) also plays crucial roles in inflammatory pain, so we evaluated the involvement of PGI2 signaling in rat inflammatory pain models using prostacyclin receptor (IP) antagonist, RO3244019. RO3244019 showed no analgesic effect in inflammatory pain models, but concomitant administration of compound I and RO3244019 showed analgesic effects comparable to celecoxib, a specific cyclooxygenase- (COX-) 2 inhibitor. Furthermore, coadministration of PGE2 receptor 4 (EP4) antagonist, CJ-023423, and RO3244019 also showed an analgesic effect. These findings suggest that both PGE2 signaling, especially through the EP4 receptor, and PGI2 signaling play critical roles in inflammatory pain and concurrent inhibition of both signals is important for suppression of inflammatory hyperalgesia. PMID:27478311

  7. Simultaneous Inhibition of PGE2 and PGI2 Signals Is Necessary to Suppress Hyperalgesia in Rat Inflammatory Pain Models.

    PubMed

    Sugita, Ryusuke; Kuwabara, Harumi; Kubota, Kazufumi; Sugimoto, Kotaro; Kiho, Toshihiro; Tengeiji, Atsushi; Kawakami, Katsuhiro; Shimada, Kohei

    2016-01-01

    Prostaglandin E2 (PGE2) is well known as a mediator of inflammatory symptoms such as fever, arthritis, and inflammatory pain. In the present study, we evaluated the analgesic effect of our selective PGE2 synthesis inhibitor, compound I, 2-methyl-2-[cis-4-([1-(6-methyl-3-phenylquinolin-2-yl)piperidin-4-yl]carbonyl amino)cyclohexyl] propanoic acid, in rat yeast-induced acute and adjuvant-induced chronic inflammatory pain models. Although this compound suppressed the synthesis of PGE2 selectively, no analgesic effect was shown in both inflammatory pain models. Prostacyclin (PGI2) also plays crucial roles in inflammatory pain, so we evaluated the involvement of PGI2 signaling in rat inflammatory pain models using prostacyclin receptor (IP) antagonist, RO3244019. RO3244019 showed no analgesic effect in inflammatory pain models, but concomitant administration of compound I and RO3244019 showed analgesic effects comparable to celecoxib, a specific cyclooxygenase- (COX-) 2 inhibitor. Furthermore, coadministration of PGE2 receptor 4 (EP4) antagonist, CJ-023423, and RO3244019 also showed an analgesic effect. These findings suggest that both PGE2 signaling, especially through the EP4 receptor, and PGI2 signaling play critical roles in inflammatory pain and concurrent inhibition of both signals is important for suppression of inflammatory hyperalgesia. PMID:27478311

  8. Extracellular matrix hyaluronan signals via its CD44 receptor in the increased responsiveness to mechanical stimulation.

    PubMed

    Ferrari, L F; Araldi, D; Bogen, O; Levine, J D

    2016-06-01

    We propose that the extracellular matrix (ECM) signals CD44, a hyaluronan receptor, to increase the responsiveness to mechanical stimulation in the rat hind paw. We report that intradermal injection of hyaluronidase induces mechanical hyperalgesia, that is inhibited by co-administration of a CD44 receptor antagonist, A5G27. The intradermal injection of low (LMWH) but not high (HMWH) molecular weight hyaluronan also induces mechanical hyperalgesia, an effect that was attenuated by pretreatment with HMWH or A5G27. Pretreatment with HMWH also attenuated the hyperalgesia induced by hyaluronidase. Similarly, intradermal injection of A6, a CD44 receptor agonist, produced hyperalgesia that was inhibited by HMWH and A5G27. Inhibitors of protein kinase A (PKA) and Src, but not protein kinase C (PKC), significantly attenuated the hyperalgesia induced by both A6 and LMWH. Finally, to determine if CD44 receptor signaling is involved in a preclinical model of inflammatory pain, we evaluated the effect of A5G27 and HMWH on the mechanical hyperalgesia associated with the inflammation induced by carrageenan. Both A5G27 and HMWH attenuated carrageenan-induced mechanical hyperalgesia. Thus, while LMWH acts at its cognate receptor, CD44, to induce mechanical hyperalgesia, HMWH acts at the same receptor as an antagonist. That the local administration of HMWH or A5G27 inhibits carrageenan-induced hyperalgesia supports the suggestion that carrageenan produces changes in the ECM that contributes to inflammatory pain. These studies define a clinically relevant role for signaling by the hyaluronan receptor, CD44, in increased responsiveness to mechanical stimulation. PMID:26996509

  9. The Area of Secondary Hyperalgesia following Heat Stimulation in Healthy Male Volunteers: Inter- and Intra-Individual Variance and Reproducibility

    PubMed Central

    Hansen, Morten Sejer; Wetterslev, Jørn; Pipper, Christian Bressen; Østervig, Rebecca; Asghar, Mohammad Sohail; Dahl, Jørgen Berg

    2016-01-01

    Introduction Clinical pain models can be applied when investigating basic physiologic pain responses in healthy volunteers. Several pain models exist; however, only few have been adequately validated. Our primary aim with this prospective study was to investigate the intra- and inter-individual variation in secondary hyperalgesia elicited by brief thermal sensitization (45°C for 3 min) in healthy volunteers. Material and Methods Fifty healthy volunteers were included. Areas of secondary hyperalgesia following brief thermal sensitization were investigated by 2 observers on 4 experimental days, with a minimum interval of 7 days. Additionally, heat pain detection threshold and pain during thermal stimulation (45°C for 1 min.), and the psychological tests Pain Catastrophizing Scale and Hospital Anxiety and Depression Score were applied. Results For areas of secondary hyperalgesia, an intra-observer intra-person correlation of 0.85, 95% CI [0.78, 0.90], an intra-observer inter-person correlation of 0.03, 95% CI [0.00, 0.16], and a coefficient of variation of 0.17, 95% CI [0.14, 0.21] was demonstrated. Four percent of the study population had areas of secondary hyperalgesia both below the 1st and above the 3rd quartile considering all included participants. Heat pain detection threshold predicted area of secondary hyperalgesia with an adjusted R2 of 0.20 (P = 0.0006). Conclusions We have demonstrated a low intra-individual, and a high inter-individual variation in thermally induced secondary hyperalgesia. We conclude that brief thermal sensitization produce secondary hyperalgesia with a high level of reproducibility, which can be applied to investigate different phenotypes related to secondary hyperalgesia in healthy volunteers. Trial Registration clinicaltrials.gov NCT02166164 PMID:27167119

  10. Study of Molecular Mechanisms Involved in the Pathogenesis of Immune-Mediated Inflammatory Diseases, using Psoriasis As a Model

    PubMed Central

    Sobolev, V.V.; Abdeev, R.M.; Zolotarenko, A.D.; Nikolaev, A.A.; Sarkisova, M.K.; Sautin, M.E.; Ishkin, A.A.; Piruzyan, An.L.; Ilyina, S.A.; Korsunskaya, I.M.; Rahimova, O.Y.; Bruskin, S.A.

    2009-01-01

    Psoriasis was used as a model to analyze the pathogenetic pathways of immune-mediated inflammatory diseases, and the results of bioinformatic, molecular-genetic and proteomic studies are provided. Cell mechanisms, common for the pathogenesis of psoriasis, as well as Crohn's disease, are identified. New approaches for immune-mediated diseases are discussed. PMID:22649625