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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.

  2. 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

  3. ASIC3 in muscle mediates mechanical, but not heat, hyperalgesia associated with muscle inflammation.

    PubMed

    Sluka, Kathleen A; Radhakrishnan, Rajan; Benson, Christopher J; Eshcol, Jayasheel O; Price, Margaret P; Babinski, Kazimierz; Audette, Katherine M; Yeomans, David C; Wilson, Steven P

    2007-05-01

    Peripheral initiators of muscle pain are virtually unknown, but likely key to development of chronic pain after muscle insult. The current study tested the hypothesis that ASIC3 in muscle is necessary for development of cutaneous mechanical, but not heat, hyperalgesia induced by muscle inflammation. Using mechanical and heat stimuli, we assessed behavioral responses in ASIC3-/- and ASIC3+/+ mice after induction of carrageenan muscle inflammation. ASIC3-/- mice did not develop cutaneous mechanical hyperalgesia after muscle inflammation when compared to ASIC3+/+ mice; heat hyperalgesia developed similarly between groups. We then tested if the phenotype could be rescued in ASIC3-/- mice by using a recombinant herpes virus vector to express ASIC3 in skin (where testing occurred) or muscle (where inflammation occurred). Infection of mouse DRG neurons with ASIC3-encoding virus resulted in functional expression of ASICs. Injection of ASIC3-encoding virus into muscle or skin of ASIC3-/- mice resulted in ASIC3 mRNA in DRG and protein expression in DRG and the peripheral injection site. Injection of ASIC3-encoding virus into muscle, but not skin, resulted in development of mechanical hyperalgesia similar to that observed in ASIC3+/+ mice. Thus, ASIC3 in primary afferent fibers innervating muscle is critical to development of hyperalgesia that results from muscle insult.

  4. ASIC3 in muscle mediates mechanical, but not heat, hyperalgesia associated with muscle inflammation

    PubMed Central

    Sluka, Kathleen A.; Radhakrishnan, Rajan; Benson, Christopher J.; Eshcol, Jayasheel O.; Price, Margaret P.; Babinski, Kazimierz; Audette, Katherine M.; Yeomans, David C.; Wilson, Steven P.

    2007-01-01

    Peripheral initiators of muscle pain are virtually unknown, but likely key to development of chronic pain after muscle insult. The current study tested the hypothesis that ASIC3 in muscle is necessary for development of cutaneous mechanical, but not heat hyperalgesia induced by muscle inflammation. Using mechanical and heat stimuli, we assessed behavioral responses in ASIC3−/− and ASIC3+/+ mice after induction of carrageenan muscle inflammation. ASIC3−/−mice did not develop cutaneous mechanical hyperalgesia after muscle inflammation when compared to ASIC3+/+ mice; heat hyperalgesia developed similarly between groups. We then tested if the phenotype could be rescued in ASIC3−/− mice by using a recombinant herpes virus vector to express ASIC3 in skin (where testing occurred) or muscle (where inflammation occurred). Infection of mouse DRG neurons with ASIC3-encoding virus resulted in functional expression of ASICs. Injection of ASIC3-encoding virus into muscle or skin of ASIC3−/− mice resulted in ASIC3 mRNA in DRG and protein expression in DRG and the peripheral injection site. Injection of ASIC3-encoding virus into muscle, but not skin, resulted in development of mechanical hyperalgesia similar to that observed in ASIC3+/+ mice. Thus, ASIC3 in primary afferent fibers innervating muscle is critical to development of hyperalgesia that results from muscle insult. PMID:17134831

  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. Mechanical stimulation enhances endothelin-1 hyperalgesia.

    PubMed

    Joseph, E K; Gear, R W; Levine, J D

    2011-03-31

    When comparing a cumulative dose-response curve for endothelin-1 (ET-1)-induced mechanical hyperalgesia to the effect of individual doses (1 ng, 10 ng, 100 ng, and 1 μg) administered in separate groups of rats, a marked difference was observed in the peak magnitude of hyperalgesia. Hyperalgesia was measured as decrease in the threshold for mechanically-induced withdrawal of the hind paw. The cumulative dosing protocol produced markedly greater maximum hyperalgesia. To determine whether this was due to the cumulative dosing protocol or to the repeated exposure to the mechanical test stimulus, we evaluated the impact of repeated testing on ET-1-induced mechanical hyperalgesia. While ET-1-induced mechanical hyperalgesia was dose- and time-dependent, repeated testing of nociceptive threshold, at 5 min intervals, following a single dose of ET-1, produced further decrease in nociceptive threshold. This mechanical stimulation-induced enhancement of ET-1 hyperalgesia lasted only 3-4 h, while the hyperalgesia lasted in excess of 5 days. The stimulation-enhanced hyperalgesia also occurred after a second injection of ET-1, administered 24 h after the initial dose. That this phenomenon is unique to ET-1 is suggested by the observation that while five additional, direct-acting hyperalgesic agents-prostaglandin E2 (PGE2), nerve growth factor (NGF), glia-derived neurotrophic factor (GDNF), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFα)-induced robust mechanical hyperalgesia, none produced mechanical stimulation-enhanced hyperalgesia.

  7. Central origin of secondary mechanical hyperalgesia.

    PubMed

    Klede, Monika; Handwerker, Hermann O; Schmelz, Martin

    2003-07-01

    The contribution for the development of secondary mechanical hyperalgesia by peripheral mechanisms has not been fully elucidated. We have reevaluated the effects of local anesthetics on electrically evoked flare reaction and mechanical hyperalgesia in human skin. We applied 2% lidocaine via intradermal microdialysis fibers at a length of 10 cm for 110 min to the volar forearm to establish a narrow and stable "anesthetic strip." After 60 min of lidocaine perfusion, transdermal electrical stimulation (1 Hz, 50 mA) was applied at a distance of 1 cm from the microdialysis fibers for 30 min. The areas of allodynia and punctate hyperalgesia were marked at the end of the stimulation period. The flare reaction was assessed by laser Doppler scanner and infrared thermography. Total protein content of the dialysate collected at the stimulating electrode was measured photometrically. We found no increase in protein content during electrical stimulation. Flare area (12.4 +/- 2.3 vs. 3.5 +/- 1.2 cm2) and intensity (426 +/- 24 vs. 257 +/- 21 PU) were significantly reduced beyond the lidocaine strip. The mean temperature increase in the area beyond the lidocaine strip was significantly reduced (1.1 +/- 0.1 vs. 0.2 +/- 0.1 degrees C) and did not differ from control areas. In contrast, allodynia (7.4 +/- 0.7 and 8.6 +/- 0.9 cm) and punctate hyperalgesia (7.6 +/- 0.7 and 8.6 +/- 0.9 cm) developed symmetrically on both sides of the anesthetic strip. Allodynia subsided 4 min after the end of the electrical stimulation. We conclude that the development of allodynia and punctate hyperalgesia in human skin is centrally mediated, whereas the axon reflex vasodilation is of peripheral origin. PMID:12843313

  8. 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

  9. Contact Hypersensitivity to Oxazolone Provokes Vulvar Mechanical Hyperalgesia in Mice

    PubMed Central

    Martinov, Tijana; Glenn-Finer, Rose; Burley, Sarah; Tonc, Elena; Balsells, Evelyn; Ashbaugh, Alyssa; Swanson, Linnea; Daughters, Randy S.; Chatterjea, Devavani

    2013-01-01

    The interplay among pain, allergy and dysregulated inflammation promises to yield significant conceptual advances in immunology and chronic pain. Hapten-mediated contact hypersensitivity reactions are used to model skin allergies in rodents but have not been utilized to study associated changes in pain perception in the affected skin. Here we characterized changes in mechanical hyperalgesia in oxazolone-sensitized female mice challenged with single and repeated labiar skin exposure to oxazolone. Female mice were sensitized with topical oxazolone on their flanks and challenged 1-3 times on the labia. We then measured mechanical sensitivity of the vulvar region with an electronic pressure meter and evaluated expression of inflammatory genes, leukocyte influx and levels of innervation in the labiar tissue. Oxazolone-sensitized mice developed vulvar mechanical hyperalgesia after a single labiar oxazolone challenge. Hyperalgesia lasted up to 24 hours along with local influx of neutrophils, upregulation of inflammatory cytokine gene expression, and increased density of cutaneous labiar nerve fibers. Three daily oxazolone challenges produced vulvar mechanical hyperalgesic responses and increases in nerve density that were detectable up to 5 days post-challenge even after overt inflammation resolved. This persistent vulvar hyperalgesia is resonant with vulvodynia, an understudied chronic pain condition that is remarkably prevalent in 18-60 year-old women. An elevated risk for vulvodynia has been associated with a history of environmental allergies. Our pre-clinical model can be readily adapted to regimens of chronic exposures and long-term assessment of vulvar pain with and without concurrent inflammation to improve our understanding of mechanisms underlying subsets of vulvodynia and to develop new therapeutics for this condition. PMID:24205293

  10. 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

  11. 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

  12. Peripheral tackykinin and excitatory amino acid receptors mediate hyperalgesia induced by Phoneutria nigriventer venom.

    PubMed

    Zanchet, Eliane Maria; Cury, Yara

    2003-04-25

    The generation of hyperalgesia by Phoneutria nigriventer venom was investigated in rats using the paw pressure test, through the intraplantar injection of the venom. Hyperalgesia was significantly inhibited by N-[2-(4-chlorophenyl) ethyl]-1,3,4,5-tetrahydro-7,8-dihydroxy-2H-2-benzazepine-2-carbothioamide (capsazepine), a vanilloid receptor antagonist, by the local administration of pGlu-Ala-Asp-Pro-Asn-Lys-Phe-Tyr-Pro (spiro-gamma-lactam) Leu-Trp-NH(2) (GR82334) or of Phenyl-CO-Ala-Ala-D-Trp-Phe-D-Pro-Pro-Nle-NH(2) (GR94800), inhibitors of tachykinin NK(1) and NK(2) receptors, respectively, or by the local injection of dizocilpine (MK 801), (+/-)-2-amino-5-phosphonopentanoic acid ((+/-)-AP-5), or 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), antagonists of NMDA and non-NMDA excitatory amino acid receptors. The correlation between hyperalgesia and the inflammatory response induced by the venom was also investigated. The venom-induced edematogenic response was not modified by the pharmacological treatments. These results suggest that hyperalgesia induced by P. nigriventer venom is mediated by stimulation of capsaicin-sensitive neurons, with activation of peripheral tachykinin NK(1) and NK(2) receptors and of both the NMDA and AMPA receptors. Distinct mechanisms are involved in the development of hyperalgesia and edema induced by the venom.

  13. 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

  14. Synthesis of Lipid Mediators during UVB-Induced Inflammatory Hyperalgesia in Rats and Mice

    PubMed Central

    Sisignano, Marco; Angioni, Carlo; Ferreiros, Nerea; Schuh, Claus-Dieter; Suo, Jing; Schreiber, Yannick; Dawes, John M.; Antunes-Martins, Ana; Bennett, David L. H.; McMahon, Stephen B.; Geisslinger, Gerd; Scholich, Klaus

    2013-01-01

    Peripheral sensitization during inflammatory pain is mediated by a variety of endogenous proalgesic mediators including a number of oxidized lipids, some of which serve endogenous modulators of sensory TRP-channels. These lipids are eicosanoids of the arachidonic acid and linoleic acid pathway, as well as lysophophatidic acids (LPAs). However, their regulation pattern during inflammatory pain and their contribution to peripheral sensitization is still unclear. Here, we used the UVB-model for inflammatory pain to investigate alterations of lipid concentrations at the site of inflammation, the dorsal root ganglia (DRGs) as well as the spinal dorsal horn and quantified 21 lipid species from five different lipid families at the peak of inflammation 48 hours post irradiation. We found that known proinflammatory lipids as well as lipids with unknown roles in inflammatory pain to be strongly increased in the skin, whereas surprisingly little changes of lipid levels were seen in DRGs or the dorsal horn. Importantly, although there are profound differences between the number of cytochrome (CYP) genes between mice and rats, CYP-derived lipids were regulated similarly in both species. Since TRPV1 agonists such as LPA 18∶1, 9- and 13-HODE, 5- and 12-HETE were elevated in the skin, they may contribute to thermal hyperalgesia and mechanical allodynia during UVB-induced inflammatory pain. These results may explain why some studies show relatively weak analgesic effects of cyclooxygenase inhibitors in UVB-induced skin inflammation, as they do not inhibit synthesis of other proalgesic lipids such as LPA 18∶1, 9-and 13-HODE and HETEs. PMID:24349046

  15. Streptozotocin-Induced Early Thermal Hyperalgesia is independent of Glycemic State of Rats: Role of Transient Receptor Potential Vanilloid 1(TRPV1) and Inflammatory mediators

    PubMed Central

    2011-01-01

    Background Streptozotocin (STZ) is used as a common tool to induce diabetes and to study diabetes-induced complications including diabetic peripheral neuropathy (DPN). Previously, we have reported that STZ induces a direct effect on neurons through expression and function of the Transient receptor potential vanilloid 1 (TRPV1) channel in sensory neurons resulting in thermal hyperalgesia, even in non-diabetic STZ-treated mice. In the present study, we investigated the role of expression and function of TRPV1 in the central sensory nerve terminals in the spinal cord in STZ-induced hyperalgesia in rats. Results We found that a proportion of STZ-treated rats were normoglycemic but still exhibited thermal hyperalgesia and mechanical allodynia. Immunohistochemical data show that STZ treatment, irrespective of glycemic state of the animal, caused microglial activation and increased expression of TRPV1 in spinal dorsal horn. Further, there was a significant increase in the levels of pro-inflammatory mediators (IL-1β, IL-6 and TNF-α) in spinal cord tissue, irrespective of the glycemic state. Capsaicin-stimulated release of calcitonin gene related peptide (CGRP) was significantly higher in the spinal cord of STZ-treated animals. Intrathecal administration of resiniferatoxin (RTX), a potent TRPV1 agonist, significantly attenuated STZ-induced thermal hyperalgesia, but not mechanical allodynia. RTX treatment also prevented the increase in TRPV1-mediated neuropeptide release in the spinal cord tissue. Conclusions From these results, it is concluded that TRPV1 is an integral component of initiating and maintaining inflammatory thermal hyperalgesia, which can be alleviated by intrathecal administration of RTX. Further, the results suggest that enhanced expression and inflammation-induced sensitization of TRPV1 at the spinal cord may play a role in central sensitization in STZ-induced neuropathy. PMID:21794120

  16. 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

  17. Melatonin Alters the Mechanical and Thermal Hyperalgesia Induced by Orofacial Pain Model in Rats.

    PubMed

    Scarabelot, Vanessa Leal; Medeiros, Liciane Fernandes; de Oliveira, Carla; Adachi, Lauren Naomi Spezia; de Macedo, Isabel Cristina; Cioato, Stefania Giotti; de Freitas, Joice S; de Souza, Andressa; Quevedo, Alexandre; Caumo, Wolnei; Torres, Iraci Lucena da Silva

    2016-10-01

    Melatonin is a neuroendocrine hormone that presents a wide range of physiological functions including regulating circadian rhythms and sleep, enhancing immune function, sleep improvement, and antioxidant effects. In addition, melatonin has received special attention in pain treatment since it is effective and presents few adverse effects. In this study, we evaluated the effect of acute dose of melatonin upon hyperalgesia induced by complete Freund's adjuvant in a chronic orofacial pain model in Sprague-Dawley rats. Nociceptive behavior was assessed by facial Von Frey and the hot plate tests at baseline and thereafter 30, 60, and 120 min, 24 h, and 7 days after melatonin treatment. We demonstrated that acute melatonin administration alters mechanical and thermal hyperalgesia induced by an orofacial pain model (TMD), highlighting that the melatonin effect upon mechanical hyperalgesia remained until 7 days after its administration. Besides, we observed specific tissue profiles of neuroimmunomodulators linked to pain conditions and/or melatonin effect (brain-derived neurotrophic factor, nerve growth factor, and interleukins 6 and 10) in the brainstem levels, and its effects were state-dependent of the baseline of these animals. PMID:27378529

  18. The chemokine CCL5 induces CCR1-mediated hyperalgesia in mice inoculated with NCTC 2472 tumoral cells.

    PubMed

    Pevida, M; Lastra, A; Meana, Á; Hidalgo, A; Baamonde, A; Menéndez, Luis

    2014-02-14

    Although the expression of the chemokine receptor CCR1 has been demonstrated in several structures related to nociception, supporting the nociceptive role of chemokines able to activate it, the involvement of CCR1 in neoplastic pain has not been previously assessed. We have assayed the effects of a CCR1 antagonist, J113863, in two murine models of neoplastic hyperalgesia based on the intratibial injection of either NCTC 2472 fibrosarcoma cells, able to induce osteolytic bone injury, or B16-F10 melanoma cells, associated to mixed osteolytic/osteoblastic bone pathological features. The systemic administration of J113863 inhibited thermal and mechanical hyperalgesia but not mechanical allodynia in mice inoculated with NCTC 2472 cells. Moreover, in these mice, thermal hyperalgesia was counteracted following the peritumoral (10-30μg) but not spinal (3-5μg) administration of J113863. In contrast, hyperalgesia and allodynia measured in mice inoculated with B16-F10 cells remained unaffected after the administration of J113863. The inoculation of tumoral cells did not modify the levels of CCL3 at tumor or spinal cord. In contrast, although the concentration of CCL5 remained unmodified in mice inoculated with B16-F10 cells, increased levels of this chemokine were measured in tumor-bearing limbs, but not the spinal cord, of mice inoculated with NCTC 2472 cells. Increased levels of CCL5 were also found following the incubation of NCTC 2472, but not B16-F10, cells in the corresponding culture medium. The intraplantar injection of CCL5 (0.5ng) to naïve mice evoked thermal hyperalgesia prevented by the coadministration of J113863 or the CCR5 antagonist, d-Ala-peptide T-amide (DAPTA), demonstrating that CCL5 can induce thermal hyperalgesia in mice through the activation of CCR1 or CCR5. However, contrasting with the inhibitory effect evoked by J113863, the systemic administration of DAPTA did not prevent tumoral hyperalgesia. Finally, the peritumoral administration of an anti

  19. 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

  20. Opioid-induced hyperalgesia: a review of epidemiology, mechanisms and management.

    PubMed

    Low, Yinghui; Clarke, Collin F; Huh, Billy K

    2012-05-01

    There has been a growing interest in opioid-induced hyperalgesia (OIH), which is an increased sensitivity to pain caused by opioid exposure. Multiple underlying pathways may contribute to the development of OIH, and the mechanism may vary with the duration of opioid exposure, dose, type and route of administration. In addition, the distinction between OIH, tolerance and withdrawal should be made in both the basic and clinical science literature so as to help translate findings to the clinical phenomenon and to help determine the best strategies to prevent or treat OIH.

  1. Inflammatory mediators involved in the paw edema and hyperalgesia induced by Batroxase, a metalloproteinase isolated from Bothrops atrox snake venom.

    PubMed

    De Toni, Lanuze G B; Menaldo, Danilo L; Cintra, Adélia C O; Figueiredo, Maria J; de Souza, Anderson R; Maximiano, William M A; Jamur, Maria C; Souza, Glória E P; Sampaio, Suely V

    2015-09-01

    Snake venom metalloproteinases have been described as responsible for several inflammatory effects. In this study, we investigated the edema and hyperalgesia induced in rats by Batroxase, a P-I metalloproteinase from Bothrops atrox venom, along with possible inflammatory mediators involved in these responses. Batroxase or sterile saline was injected into rat paws and the edema and hyperalgesic effects were evaluated for 6h by using a plethysmometer and a Von Frey system, respectively. Batroxase induced significant edematogenic and hyperalgesic peak responses in the first hours after administration. The inflammatory mediators involved in these responses were assayed by pretreatment of animals with synthesis inhibitors or receptor antagonists. Peak responses were significantly reduced by administration of the glucocorticoid dexamethasone, the H1 receptor antagonist diphenhydramine and the FLAP inhibitor MK-886. Rat paws injected with compound 48/80, a mast cell degranulating agent, followed by Batroxase injection resulted in significant reduction of the edema and hyperalgesia. However, Batroxase itself induced minor degranulation of RBL-2H3 mast cells in vitro. Additionally, the inflammatory responses did not seem to be related to prostaglandins, bradykinin or nitric oxide. Our results indicate a major involvement of histamine and leukotrienes in the edema and hyperalgesia induced by Batroxase, which could be related, at least in part, to mast cell degranulation. PMID:26072684

  2. 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

  3. 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

  4. Lowering barometric pressure aggravates mechanical allodynia and hyperalgesia in a rat model of neuropathic pain.

    PubMed

    Sato, J; Morimae, H; Seino, Y; Kobayashi, T; Suzuki, N; Mizumura, K

    1999-04-30

    To examine the effects of meteorological change on the pain-related behaviors of neuropathic rats, animals with a chronic constriction injury (CCI) to the sciatic nerve were exposed to low barometric pressure (LP), 20 mmHg below the natural atmospheric pressure in a climate-controlled room. CCI caused a decreased hindpaw withdrawal threshold to von Frey hair (VFH) stimulation (mechanical allodynia) and prolonged duration of hindpaw withdrawal in response to pinprick stimulation (mechanical hyperalgesia). When the CCI rats were exposed to LP, both these pain-related behaviors were aggravated, whereas no change was seen in a group of controls. In the CCI rats sympathectomy inhibited this LP-induced augmentation of pain-related behaviors. These results show that LP intensifies the abnormalities in the pain-related behaviors of neuropathic rats, and that sympathetic activity contributes to the LP effect.

  5. 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

  6. 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

  7. Is mechanism and symptom-based analgesia an answer to opioid-induced hyperalgesia?

    PubMed

    Gupta, Mayank; Gupta, Priyanka

    2015-01-01

    "Cancer Pain" and "Pain in cancer patient" are not synonymous. Opioid-induced Hyperalgesia (OIH) is a paradoxical state of nociceptive sensitization caused by exposure to opioids. Neuropathic pain is only partially responsive to opioids; injudicious increase in dose of opioids in neuropathic pain may not only result in inadequate pain relief but also OIH. Majority of literature on OIH is in non-cancer pain with systemic use of opioids. We describe the development and successful treatment of OIH in a 55-year-old male patient with Small cell Carcinoma Lung. Opioid tapering, rotation, systemic desensitization helps in combatting OIH. The use of anti-neuropathic adjuvant analgesics helps not only in preventing and treating OIH but also in understanding putative mechanisms underlying neuropathic pain and OIH.

  8. 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

  9. Protection against oxaliplatin-induced mechanical hyperalgesia and intraepidermal nerve fiber loss by minocycline.

    PubMed

    Boyette-Davis, J; Dougherty, P M

    2011-06-01

    Treatment with the chemotherapeutic agent oxaliplatin produces a robust painful neuropathy similar to various other neuropathic conditions which result in loss of nerve fibers innervating the skin. This loss of intraepidermal nerve fibers (IENFs) appears to play an important role in neuropathy, but has yet to be investigated in oxaliplatin-induced neuropathic pain. For this study, mechanical hyperalgesia and IENF density were measured in rats receiving oxaliplatin, given at a dosage of 2 mg/kg every other day for four injections. The immunomodulatory agent minocycline (25 mg/kg) was also administered and was given 24 h prior to the first dose of oxaliplatin and continued throughout oxaliplatin treatment. Immunohistochemistry using the pan-neuronal marker PGP9.5 was used to investigate IENF densities in hind paw skin on Day 15 and Day 30. The results show that a robust mechanical sensitivity developed in oxaliplatin treated animals, as did a pronounced decrease in epidermal nerve fibers, and these outcomes were effectively prevented by minocycline treatment. This is the first study to show changes in IENF density in oxaliplatin treated animals, and confirm not only a relationship between IENF loss and hypersensitivity but also prevention of both with minocycline treatment.

  10. Peripheral involvement of PKA and PKC in subcutaneous bee venom-induced persistent nociception, mechanical hyperalgesia, and inflammation in rats.

    PubMed

    Chen, Hui-Sheng; Lei, Jing; He, Xiang; Qu, Fang; Wang, Yang; Wen, Wei-Wei; You, Hao-Jun; Arendt-Nielsen, Lars

    2008-03-01

    The roles of central protein kinases A and C (PKA and PKC) in various pain states have intensively been investigated during the past decade. The aim of the present study was to investigate the peripheral involvement of PKA and PKC in persistent nociceptive response, evoked pain behaviors, and inflammation induced by subcutaneous (s.c.) injection of bee venom (BV, 0.2mg/50 microl) in rats. The effects of intraplantar injection of H-89 (a PKA inhibitor, 5-100 microg/50 microl) and chelerythrine chloride (a PKC inhibitor, 5-100 microg/50 microl) on BV-elicited persistent nociception (nociceptive flinching reflex), mechanical hyperalgesia, and inflammation were systematically investigated. Pre-treatment with H-89 dose-dependently inhibited only BV-induced mechanical hyperalgesia, but not the persistent nociception and inflammation. In contrast, pre-treatment with chelerythrine chloride dose-dependently inhibited BV-induced sustained nociception and inflammation, but not the mechanical hyperalgesia. Topical pre-treatment of the sciatic nerve with 1% capsaicin significantly blocked the inhibitory effects of the PKC inhibitor on BV-induced inflammation, but not the persistent flinching response. These results indicate that peripheral PKA and PKC involvements in BV-induced pain behaviors differ, and capsaicin-sensitive afferents appear to participate in the pro-inflammatory role of PKC in the BV pain model. Findings from the present study also suggest that targeting specific peripheral protein kinases might prove effective in the treatment of persistent pain and inflammation.

  11. 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

  12. 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.

  13. Activation of the alpha-7 nicotinic acetylcholine receptor (α7 nAchR) reverses referred mechanical hyperalgesia induced by colonic inflammation in mice.

    PubMed

    Costa, Robson; Motta, Emerson M; Manjavachi, Marianne N; Cola, Maíra; Calixto, João B

    2012-10-01

    In the current study, we investigated the effect of the activation of the alpha-7 nicotinic acetylcholine receptor (α7 nAchR) on dextran sulphate sodium (DSS)-induced colitis and referred mechanical hyperalgesia in mice. Colitis was induced in CD1 male mice through the intake of 4% DSS in tap water for 7 days. Control mice received unadulterated water. Referred mechanical hyperalgesia was evaluated for 7 days after the beginning of 4% DSS intake. Referred mechanical hyperalgesia started within 1 day after beginning DSS drinking, peaked at 3 days and persisted for 7 days. This time course profile perfectly matched with the appearance of signs of colitis. Both acute and chronic oral treatments with nicotine (0.1-1.0 mg/kg, p.o.) were effective in inhibiting the established referred mechanical hyperalgesia. The antinociceptive effect of nicotine was completely abrogated by cotreatment with the selective α7 nAchR antagonist methyllycaconitine (MLA) (1.0 mg/kg). Consistent with these results, i.p. treatment with the selective α7 nAchR agonist PNU 282987 (0.1-1.0 mg/kg) reduced referred mechanical hyperalgesia at all periods of evaluation. Despite their antinociceptive effects, nicotinic agonists did not affect DSS-induced colonic damage or inflammation. Taken together, the data generated in the present study show the potential relevance of using α7 nAchR agonists to treat referred pain and discomfort associated with inflammatory bowel diseases.

  14. Increasing 2-arachidonoyl glycerol signaling in the periphery attenuates mechanical hyperalgesia in a model of bone cancer pain

    PubMed Central

    Khasabova, Iryna A.; Chandiramani, Anisha; Harding-Rose, Catherine; Simone, Donald A.; Seybold, Virginia S.

    2011-01-01

    Metastatic and primary bone cancers are usually accompanied by severe pain that is difficult to manage. In light of the adverse side effects of opioids, manipulation of the endocannabinoid system may provide an effective alternative for the treatment of cancer pain. The present study determined that a local, peripheral increase in the endocannabinoid 2-arachidonoylglycgerol (2-AG) reduced mechanical hyperalgesia evoked by the growth of a fibrosarcoma tumor in and around the calcaneous bone. Intraplantar (ipl) injection of 2-AG attenuated hyperalgesia (ED50 of 8.2 μg) by activation of peripheral CB2 but not CB1 receptors and had an efficacy comparable to that of morphine. JZL184 (10 μg, ipl.), an inhibitor of 2-AG degradation, increased the local level of 2AG and mimicked the antihyperalgesic effect of 2-AG, also through a CB2 receptor-dependent mechanism. These effects were accompanied by an increase in CB2 receptor protein in plantar skin of the tumor-bearing paw as well as an increase in the level of 2AG. In naïve mice, intraplantar administration of the CB2 receptor antagonist AM630 did not alter responses to mechanical stimuli demonstrating that peripheral CB2 receptor tone does not modulate mechanical sensitivity. These data extend our previous findings with anandamide in the same model and suggest that the peripheral endocannabinoid system is a promising target for the management of cancer pain. PMID:21440630

  15. Opioid induced hyperalgesia altered with propofol infusion.

    PubMed

    Kaye, Alan D; Chung, Keun Sam; Vadivelu, Nalini; Cantemir, Catalin; Urman, Richard D; Manchikanti, Laxmaiah

    2014-01-01

    Propofol is a common induction agent that is utilized worldwide in the field of anesthesiology. In recent years, its potential therapeutic role in a variety of patient states has been demonstrated. Controversy exists regarding Propofol mediated analgesic and antihyperalgesic properties. Recent studies have suggested a variety of different mechanisms of action, including modulation of N-Methyl-D- Aspartate receptors and the endocannabinoid system. The N-Methyl-D- Aspartate receptor is part of a larger family of glutamate receptors and is an important mediator of excitatory neurotransmission. In the case presented, the pain experienced by the patient was not well-controlled, in spite of increasing doses of opioids, potentially due to superimposed opioid induced hyperalgesia. In the present case, we demonstrate a cycle of opioid induced hyperalgesia which was successfully affected with a Propofol infusion. Controversial reports exist in animal studies on the analgesic properties of Propofol. Randomized controlled studies in animal models studying the effect of Propofol on pain sensation have shown that Propofol possesses an analgesic effect. This clinical case demonstrates that Propofol could possibly have antihyperalgesic effects on opioid induced hyperalgesia caused by high-doses of chronic opioids and worsened by fentanyl. We postulate that a probable mechanism of complete pain relief after the procedure could be the inhibition of activity of the N-Methyl-D- Aspartate receptor by Propofol because it was the only agent the patient received during the procedure, causing a break of the cycle of opioid induced hyperalgesia. Additional research is required to clarify Propofol mediated or modulated analgesic properties in humans.

  16. Unity vs. diversity of neuropathic pain mechanisms: Allodynia and hyperalgesia in rats selected for heritable predisposition to spontaneous pain.

    PubMed

    Ziv-Sefer, Sagit; Raber, Pnina; Barbash, Shahar; Devor, Marshall

    2009-11-01

    Do contrasting neuropathic pain diagnoses share common pathophysiological mechanisms? Selective breeding was used to derive rat lines with a common genetic background but a striking difference in the degree of spontaneous pain behavior expressed in the neuroma model of neuropathic pain (HA rats (high autotomy) and LA rats (low autotomy)). The contrasting pain phenotype in these lines is attributable to allelic differences at a small number of genetic loci. Here we show that HA and LA rats also differ in their nocifensive response to applied stimuli in the Chung (spinal nerve ligation, SNL) model of neuropathic pain. This includes tactile allodynia and hyperalgesia, and heat allodynia. The degree of hypersensibility varied with sex, age at the time of nerve injury, and the extent of the nerve lesion. F1 crosses of HA and LA rats and inbred Lewis rats showed low levels of autotomy but variable levels of hypersensibility to applied stimuli. Results indicate that alleles which predispose to spontaneous neuropathic pain also predispose to stimulus-evoked pain (allodynia and hyperalgesia). This, in turn, suggests that despite contrasting etiology and behavioral endpoints, pain phenotype in the neuroma and the SNL models shares common pathophysiological mechanisms. PMID:19683390

  17. Deletion of the CCK2 receptor gene reduces mechanical sensitivity and abolishes the development of hyperalgesia in mononeuropathic mice.

    PubMed

    Kurrikoff, Kaido; Kõks, Sulev; Matsui, Toshimitsu; Bourin, Michel; Arend, Andres; Aunapuu, Marina; Vasar, Eero

    2004-09-01

    Previous studies suggest that cholecystokinin (CCK) is implicated in the modulation of pain sensitivity and the development of neuropathic pain. We used CCK(2) receptor deficient (CCK(2) (-/-)) mice and assessed their mechanical sensitivity using Von Frey filaments, as well as the development and time course of mechanical hyperalgesia in a model of neuropathic pain. We found that CCK(2) (-/-) mice displayed mechanical hyposensitivity, which was reversed to the level of wild-type animals after administration of naloxone (0.1-10 mg/kg). On the other hand, injection of L-365260 (0.01-1 mg/kg), an antagonist of CCK(2) receptors, decreased dose-dependently, mechanical sensitivity in wild-type mice. The mechanism of reduced mechanical sensitivity in CCK(2) (-/-) mice may be explained by changes in interactions between CCK and opioid systems. Indeed, CCK(2) (-/-) mice natively expressed higher levels of lumbar CCK(1), opioid delta and kappa receptors. Next, we found that CCK(2) (-/-) mice did not develop mechanical hyperalgesia in the Bennett's neuropathic pain model. Induction of neuropathy resulted in decrease of lumbar pro-opiomelanocortin (POMC) gene expression in wild-type mice, but increase of POMC expression in CCK(2) (-/-) mice. In addition, induction of neuropathy resulted in further increase of opioid delta receptor in CCK(2) (-/-) mice. Gene expression results indicate up-regulation of opioid system in CCK(2) (-/-) mice, which apparently result in decreased neuropathy score. Our study suggests that not only pain sensitivity, but also mechanical sensitivity and the development of neuropathic pain are regulated by antagonistic interactions between CCK and opioid systems.

  18. 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.

  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. Toll-like receptor 4-mediated nuclear factor-κB activation in spinal cord contributes to chronic morphine-induced analgesic tolerance and hyperalgesia in rats.

    PubMed

    Bai, Liying; Zhai, Caihong; Han, Kun; Li, Zhisong; Qian, Junliang; Jing, Ying; Zhang, Wei; Xu, Ji-Tian

    2014-12-01

    Nuclear factor kappa B (NF-κB) in the spinal cord is involved in pro-inflammatory cytokine-mediated pain facilitation. However, the role of NF-κB activation in chronic morphine-induced analgesic tolerance and the underlying mechanisms remain unclear. In the present study, we found that the level of phosphorylated NF-κB p65 (p-p65) was increased in the dorsal horn of the lumbar 4-6 segments after intrathecal administration of morphine for 7 consecutive days, and the p-p65 was co-localized with neurons and astrocytes. The expression of TNF-α and IL-1β was also increased in the same area. In addition, pretreatment with pyrrolidinedithiocarbamate (PDTC) or SN50, inhibitors of NF-κB, prevented the development of morphine analgesic tolerance and alleviated morphine withdrawal-induced allodynia and hyperalgesia. The increase in TNF-α and IL-1β expression induced by chronic morphine exposure was also partially blocked by PDTC pretreatment. In another experiment, rats receiving PDTC or SN50 beginning on day 7 of morphine injection showed partial recovery of the anti-nociceptive effects of morphine and attenuation of the withdrawal-induced abnormal pain. Meanwhile, intrathecal pretreatment with lipopolysaccharide from Rhodobacter sphaeroides, an antagonist of toll-like receptor 4 (TLR4), blocked the activation of NF-κB, and prevented the development of morphine tolerance and withdrawal-induced abnormal pain. These data indicated that TLR4-mediated NF-κB activation in the spinal cord is involved in the development and maintenance of morphine analgesic tolerance and withdrawal-induced pain hypersensitivity.

  1. Toll-like receptor 4-mediated nuclear factor-κB activation in spinal cord contributes to chronic morphine-induced analgesic tolerance and hyperalgesia in rats.

    PubMed

    Bai, Liying; Zhai, Caihong; Han, Kun; Li, Zhisong; Qian, Junliang; Jing, Ying; Zhang, Wei; Xu, Ji-Tian

    2014-12-01

    Nuclear factor kappa B (NF-κB) in the spinal cord is involved in pro-inflammatory cytokine-mediated pain facilitation. However, the role of NF-κB activation in chronic morphine-induced analgesic tolerance and the underlying mechanisms remain unclear. In the present study, we found that the level of phosphorylated NF-κB p65 (p-p65) was increased in the dorsal horn of the lumbar 4-6 segments after intrathecal administration of morphine for 7 consecutive days, and the p-p65 was co-localized with neurons and astrocytes. The expression of TNF-α and IL-1β was also increased in the same area. In addition, pretreatment with pyrrolidinedithiocarbamate (PDTC) or SN50, inhibitors of NF-κB, prevented the development of morphine analgesic tolerance and alleviated morphine withdrawal-induced allodynia and hyperalgesia. The increase in TNF-α and IL-1β expression induced by chronic morphine exposure was also partially blocked by PDTC pretreatment. In another experiment, rats receiving PDTC or SN50 beginning on day 7 of morphine injection showed partial recovery of the anti-nociceptive effects of morphine and attenuation of the withdrawal-induced abnormal pain. Meanwhile, intrathecal pretreatment with lipopolysaccharide from Rhodobacter sphaeroides, an antagonist of toll-like receptor 4 (TLR4), blocked the activation of NF-κB, and prevented the development of morphine tolerance and withdrawal-induced abnormal pain. These data indicated that TLR4-mediated NF-κB activation in the spinal cord is involved in the development and maintenance of morphine analgesic tolerance and withdrawal-induced pain hypersensitivity. PMID:25446875

  2. Analgesic Effect of Photobiomodulation on Bothrops Moojeni Venom-Induced Hyperalgesia: A Mechanism Dependent on Neuronal Inhibition, Cytokines and Kinin Receptors Modulation

    PubMed Central

    Oliveira, Victoria Regina da Silva; Toniolo, Elaine Flamia; Feliciano, Regiane dos Santos; da Silva Jr., José Antonio; Zamuner, Stella Regina

    2016-01-01

    Background Envenoming induced by Bothrops snakebites is characterized by drastic local tissue damage that involves an intense inflammatory reaction and local hyperalgesia which are not neutralized by conventional antivenom treatment. Herein, the effectiveness of photobiomodulation to reduce inflammatory hyperalgesia induced by Bothrops moojeni venom (Bmv), as well as the mechanisms involved was investigated. Methodology/Principal Findings Bmv (1 μg) was injected through the intraplantar route in the right hind paw of mice. Mechanical hyperalgesia and allodynia were evaluated by von Frey filaments at different time points after venom injection. Low level laser therapy (LLLT) was applied at the site of Bmv injection at wavelength of red 685 nm with energy density of 2.2 J/cm2 at 30 min and 3 h after venom inoculation. Neuronal activation in the dorsal horn spinal cord was determined by immunohistochemistry of Fos protein and the mRNA expression of IL-6, TNF-α, IL-10, B1 and B2 kinin receptors were evaluated by Real time-PCR 6 h after venom injection. Photobiomodulation reversed Bmv-induced mechanical hyperalgesia and allodynia and decreased Fos expression, induced by Bmv as well as the mRNA levels of IL-6, TNF-α and B1 and B2 kinin receptors. Finally, an increase on IL-10, was observed following LLLT. Conclusion/Significance These data demonstrate that LLLT interferes with mechanisms involved in nociception and hyperalgesia and modulates Bmv-induced nociceptive signal. The use of photobiomodulation in reducing local pain induced by Bothropic venoms should be considered as a novel therapeutic tool for the treatment of local symptoms induced after bothropic snakebites. PMID:27749899

  3. Myelinated Afferents Are Involved in Pathology of the Spontaneous Electrical Activity and Mechanical Hyperalgesia of Myofascial Trigger Spots in Rats

    PubMed Central

    2015-01-01

    Myofascial trigger points (MTrPs) are common causes for chronic pain. Myelinated afferents were considered to be related with muscular pain, and our clinical researches indicated they might participate in the pathology of MTrPs. Here, we applied myofascial trigger spots (MTrSs, equal to MTrPs in human) of rats to further investigate role of myelinated afferents. Modified pyridine-silver staining revealed more nerve endings at MTrSs than non-MTrSs (P < 0.01), and immunohistochemistry with Neurofilament 200 indicated more myelinated afferents existed in MTrSs (P < 0.01). Spontaneous electrical activity (SEA) recordings at MTrSs showed that specific block of myelinated afferents in sciatic nerve with tetrodotoxin (TTX) led to significantly decreased SEA (P < 0.05). Behavioral assessment showed that mechanical pain thresholds (MPTs) of MTrSs were lower than those of non-MTrSs (P < 0.01). Block of myelinated afferents by intramuscular TTX injection increased MPTs of MTrSs significantly (P < 0.01), while MPTs of non-MTrSs first decreased (P < 0.05) and then increased (P > 0.05). 30 min after the injection, MPTs at MTrSs were significantly lower than those of non-MTrSs (P < 0.01). Therefore, we concluded that proliferated myelinated afferents existed at MTrSs, which were closely related to pathology of SEA and mechanical hyperalgesia of MTrSs. PMID:26064165

  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. Phosphorylation of the GluN1 subunit in dorsal horn neurons by remifentanil: a mechanism for opioid-induced hyperalgesia.

    PubMed

    Zhang, C; Li, S S; Zhao, N; Yu, C

    2015-03-13

    Remifentanil (an ultra-short acting μ-opioid receptor agonist) use has been associated with acute opioid tolerance and hyperalgesia. Previous electrophysiological studies have shown that remifentanil elicits rapid and prolonged upregulation of N-methyl-D-aspartate receptor (NMDAR) currents. However, the effect of remifentanil on the levels of the GluN1 subunit of the NMDAR in dorsal horn neurons (DHNs) has not been reported. We investigated the effect of remifentanil, along with ketamine (NMDAR antagonist) and naloxone (μ-opioid receptor antagonist), on GluN1 mRNA levels and the amount of phosphorylated GluN1 in primary cultures of embryonic rat DHNs. DHNs were isolated from 18-19-day rat embryos and treated with remifentanil or vehicle for 1 h. GluN1 mRNA and protein levels, determined by real time reverse transcription polymerase chain reaction (RT-PCR) and Western blot, respectively, were significantly and persistently increased by remifentanil exposure compared with the control group (P < 0.05). These results may partially account for the mechanism of remifentanil-induced hyperalgesia. This increase was prevented by ketamine (NMDAR antagonist) and naloxone (μ-opioid receptors antagonist), thus providing a potential therapeutic mechanism for the prevention of opioid-induced hyperalgesia.

  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. Paclitaxel-induced hyperalgesia modulates negative affective component of pain and NR1 receptor expression in the frontal cortex in rats.

    PubMed

    Noda, Kazuko; Akita, Hisanao; Ogata, Masanori; Saji, Makoto

    2014-03-01

    Paclitaxel, one of the chemotherapeutic agents clinically used to treat several types of cancer, produces side effects such as peripheral neuropathy, sensory abnormalities, and hyperalgesia. Since hyperalgesia remains after cessation of paclitaxel therapy and becomes chronic, we hypothesize that alteration in memory and the cognitive process of pain underlies hyperalgesia. To test this hypothesis, we examined whether drug-induced hyperalgesia alters the affective component of pain and the NMDA-NR1 and mGluR1 receptors as a mediator for signal transmission and memory of pain. Mechanical sensitivity was measured by von Frey filament test after intraperitoneal injection of paclitaxel in rats. Paclitaxel-induced hyperalgesia was confirmed over almost the entire 14-day period of observation after the treatment. The effect of paclitaxel-induced hyperalgesia on the affective component of pain was assessed using pain-induced place aversion. The formalin-induced conditioned place aversion was completely abolished in the paclitaxel-treated rats. Immunoblot analysis of NR1 and mGluR1 protein levels in various brain regions was performed after paclitaxel treatment. Treatment reduced only the NR1 expression within the frontal cortex. These results suggest that the hypofunction of memory processes with the reduced NMDA receptors in the frontal cortex might be involved in the expression of abnormal emotional behaviors accompanied by hyperalgesia.

  9. The kainate receptor antagonist 2S,4R-4-methylglutamate attenuates mechanical allodynia and thermal hyperalgesia in a rat model of nerve injury.

    PubMed

    Sutton, J L; Maccecchini, M L; Kajander, K C

    1999-01-01

    Opioids and receptor antagonists of excitatory amino acids attenuate mechanical allodynia and thermal hyperalgesia in animal models of neuropathic pain. Recently, a kainate receptor antagonist, 2S,4R-4-methylglutamate, has been developed but has not been tested for antinociceptive effects in animal models of neuropathic pain. We evaluated whether 2S,4R-4-methylglutamate attenuated responses to mechanical and thermal stimuli in uninjured (control) rats and increased responsiveness in rats with chronic constriction injury. Rats were tested for a number of withdrawal responses using a calibrated von Frey filament (mechanical stimulus) and withdrawal latencies from a radiant heat source (thermal stimulus). In control rats, 2S,4R-4-methylglutamate produced a small but significant decrease in responses from the mechanical stimulus (25 mg/kg) and significantly increased withdrawal latencies from the thermal stimulus at the highest dose administered (100 mg/kg). In addition, 2S,4R-4-methylglutamate greatly attenuated increased responsiveness in rats with chronic constriction injury. At four to eight days following chronic constriction injury, animals that displayed increased responsiveness to mechanical and thermal stimuli were injected intraperitoneally with either dizocilpine maleate (0.1 mg/kg), morphine (4 mg/kg), vehicle as controls, or 2S,4R-4-methylglutamate (25, 50, 75 or 100 mg/kg). 2S,4R-4-Methylglutamate (25, 50, 75 and 100 mg/kg) significantly attenuated the frequency of responses to mechanical stimuli (Wilcoxon, P < 0.05) and the latency of responses to thermal stimuli (analysis of variance and Duncan's, P < 0.05). Dizocilpine maleate and morphine, as expected, also reduced these responses. These results suggest that, in addition to opioid and N-methyl-D-aspartate receptors, kainate receptors may play a role in the maintenance of mechanical allodynia and thermal hyperalgesia associated with peripheral nerve injury.

  10. 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

  11. Antibody directed against GD(2) produces mechanical allodynia, but not thermal hyperalgesia when administered systemically or intrathecally despite its dependence on capsaicin sensitive afferents.

    PubMed

    Sorkin, L S; Yu, A L; Junger, H; Doom, C M

    2002-03-15

    Anti-GD(2) antibodies have been shown to be effective for immunotherapy of neuroblastoma and other GD(2) enriched malignancies. Infusion of anti-GD(2) antibodies frequently causes spontaneous pain and allodynia for the duration of the immunotherapy and occasionally longer lasting neuropathic pain. Bolus intravenous injection of anti-GD(2) in rats initiates mechanical allodynia as measured by withdrawal threshold of the hindpaws. In this study, thermal thresholds were measured prior to and for up to 6 h following systemic anti-GD(2) administration in adult rats. In addition, both thermal and mechanical thresholds were tested following intrathecal administration of anti-GD(2) and IgG(2a). Murine anti-GD(2) elicited mechanical allodynia when administered into either the vasculature or the intrathecal space. Effective systemic doses were 1--3 mg/kg as previously shown. Intrathecally, optimal doses ranged from 0.01 to 0.1 ng; a higher dose was ineffective. Thermal hyperalgesia was not observed via either route of administration. Intrathecal pretreatment 48--72 h prior to the experiment with capsaicin at doses sufficient to cause a 50% depletion of dorsal horn CGRP, caused a total blockade of the mechanical allodynia indicating an involvement of peptidergic fine afferent fibers. It is likely that the antibody reacts with an antigen on peripheral nerve and/or myelin to initiate its effect. The lack of observed thermal hyperalgesia is surprising especially in light of the capsaicin-associated blockade, however, it is consistent with several other immune system related models of pain.

  12. Effect of Intraperitoneal Administered Ginseng Total Saponins on Hyperalgesia Induced by Repeated Intramuscular Injection of Acidic Saline in Rats

    PubMed Central

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

    2014-01-01

    Abstract 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

  13. Heat hyperalgesia after incision requires TRPV1 and is distinct from pure inflammatory pain.

    PubMed

    Pogatzki-Zahn, Esther M; Shimizu, Isao; Caterina, Michael; Raja, Srinivasa N

    2005-06-01

    Postoperative pain significantly impacts patient recovery. However, postoperative pain management remains suboptimal, perhaps because treatment strategies are based mainly on studies using inflammatory pain models. We used a recently developed mouse model of incisional pain to investigate peripheral and spinal mechanisms contributing to heat hyperalgesia after incision. Behavioral experiments involving TRPV1 KO mice demonstrate that, as previously observed in inflammatory models, TRPV1 is necessary for heat (but not mechanical) hyperalgesia after incision. However, in WT mice, neither the proportion of TRPV1 immunoreactive neurons in the DRG nor the intensity of TRPV1 staining in the sciatic nerve was different from that in controls up to 4 days after incision. This result was corroborated by immunoblot analysis of sciatic nerve in rats subjected to an incision, and is distinct from that following inflammation of the rat hind paw, a situation in which TRPV1 expression levels in sciatic nerve increases. In the absence of heat exposure, spinal c-Fos staining was similar between incised TRPV1 KO and WT mice. However, differences in c-Fos staining between heat exposed TRPV1 KO and WT mice after incision suggest that the incision-mediated enhancement of heat-evoked signaling to the spinal cord involves a TRPV1-dependent mechanism. Finally, heat hyperalgesia after incision was reversed by antagonism of spinal non-NMDA receptors, unlike inflammatory hyperalgesia, which is mediated via NMDA receptors . Thus, TRPV1 is important for the generation of thermal hyperalgesia after incision. Our observations suggest that all experimental pain models may not be equally appropriate to guide the development of postoperative pain therapies.

  14. An Improved Model of Heat-Induced Hyperalgesia—Repetitive Phasic Heat Pain Causing Primary Hyperalgesia to Heat and Secondary Hyperalgesia to Pinprick and Light Touch

    PubMed Central

    Henrich, Florian; Magerl, Walter; May, Arne

    2014-01-01

    This study tested a modified experimental model of heat-induced hyperalgesia, which improves the efficacy to induce primary and secondary hyperalgesia and the efficacy-to-safety ratio reducing the risk of tissue damage seen in other heat pain models. Quantitative sensory testing was done in eighteen healthy volunteers before and after repetitive heat pain stimuli (60 stimuli of 48°C for 6 s) to assess the impact of repetitive heat on somatosensory function in conditioned skin (primary hyperalgesia area) and in adjacent skin (secondary hyperalgesia area) as compared to an unconditioned mirror image control site. Additionally, areas of flare and secondary hyperalgesia were mapped, and time course of hyperalgesia determined. After repetitive heat pain conditioning we found significant primary hyperalgesia to heat, and primary and secondary hyperalgesia to pinprick and to light touch (dynamic mechanical allodynia). Acetaminophen (800 mg) reduced pain to heat or pinpricks only marginally by 11% and 8%, respectively (n.s.), and had no effect on heat hyperalgesia. In contrast, the areas of flare (−31%) and in particular of secondary hyperalgesia (−59%) as well as the magnitude of hyperalgesia (−59%) were significantly reduced (all p<0.001). Thus, repetitive heat pain induces significant peripheral sensitization (primary hyperalgesia to heat) and central sensitization (punctate hyperalgesia and dynamic mechanical allodynia). These findings are relevant to further studies using this model of experimental heat pain as it combines pronounced peripheral and central sensitization, which makes a convenient model for combined pharmacological testing of analgesia and anti-hyperalgesia mechanisms related to thermal and mechanical input. PMID:24911787

  15. 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

  16. Acid evoked thermal hyperalgesia involves peripheral P2Y1 receptor mediated TRPV1 phosphorylation in a rodent model of thrombus induced ischemic pain

    PubMed Central

    2014-01-01

    Background We previously developed a thrombus-induced ischemic pain (TIIP) animal model, which was characterized by chronic bilateral mechanical allodynia without thermal hyperalgesia (TH). On the other hand we had shown that intraplantar injection of acidic saline facilitated ATP-induced pain, which did result in the induction of TH in normal rats. Because acidic pH and increased ATP are closely associated with ischemic conditions, this study is designed to: (1) examine whether acidic saline injection into the hind paw causes the development of TH in TIIP, but not control, animals; and (2) determine which peripheral mechanisms are involved in the development of this TH. Results Repeated intraplantar injection of pH 4.0 saline, but not pH 5.5 and 7.0 saline, for 3 days following TIIP surgery resulted in the development of TH. After pH 4.0 saline injections, protein levels of hypoxia inducible factor-1α (HIF-1α) and carbonic anhydrase II (CA II) were elevated in the plantar muscle indicating that acidic stimulation intensified ischemic insults with decreased tissue acidity. At the same time point, there were no changes in the expression of TRPV1 in hind paw skin, whereas a significant increase in TRPV1 phosphorylation (pTRPV1) was shown in acidic saline (pH 4.0) injected TIIP (AS-TIIP) animals. Moreover, intraplantar injection of chelerythrine (a PKC inhibitor) and AMG9810 (a TRPV1 antagonist) effectively alleviated the established TH. In order to investigate which proton- or ATP-sensing receptors contributed to the development of TH, amiloride (an ASICs blocker), AMG9810, TNP-ATP (a P2Xs antagonist) or MRS2179 (a P2Y1 antagonist) were pre-injected before the pH 4.0 saline. Only MRS2179 significantly prevented the induction of TH, and the increased pTRPV1 ratio was also blocked in MRS2179 injected animals. Conclusion Collectively these data show that maintenance of an acidic environment in the ischemic hind paw of TIIP rats results in the phosphorylation of

  17. Deficits in visceral pain and hyperalgesia of mice with a disruption of the tachykinin NK1 receptor gene.

    PubMed

    Laird, J M; Olivar, T; Roza, C; De Felipe, C; Hunt, S P; Cervero, F

    2000-01-01

    Studies in mice lacking genes encoding for substance P or its receptor (NK1), or with NK1 antagonists, have shown that this system contributes to nociception, but the data are complex. Here, we have further examined the role of NK1 receptors in pain and hyperalgesia by comparing nociceptive responses to mechanical and chemical stimulation of viscera and the resulting hyperalgesia and inflammation in NK1 knockout (-/-) and wild-type (+/+) mice. We concentrated on visceral nociception because substance P is expressed by a much greater proportion of visceral than cutaneous afferents. NK1 -/- mice showed normal responses to visceral mechanical stimuli, measured as behavioural responses to intraperitoneal acetylcholine or hypertonic saline or reflex responses to colon distension in anaesthetized mice, although -/- mice failed to encode the intensity of noxious colon distensions. In contrast, NK1 -/- mice showed profound deficits in spontaneous behavioural reactions to an acute visceral chemical stimulus (intracolonic capsaicin) and failed to develop referred hyperalgesia or tissue oedema. However, in an identical procedure, intracolonic mustard oil evoked normal spontaneous behaviour, referred hyperalgesia and oedema in -/- mice. The inflammatory effects of capsaicin were abolished by denervation of the extrinsic innervation of the colon in rats, whereas those of mustard oil were unchanged, showing that intracolonic capsaicin evokes neurogenic inflammation, but mustard oil does not. Tests of other neurogenic inflammatory stimuli in NK1 -/- mice revealed impaired behavioural responses to cyclophosphamide cystitis and no acute reflex responses or primary hyperalgesia to intracolonic acetic acid. We conclude that NK1 receptors have an essential role mediating central nociceptive and peripheral inflammatory responses to noxious stimuli that evoke neurogenic inflammation, and modulating responses to noxious mechanical stimuli. We propose that two separate hyperalgesia

  18. Minocycline blocks lipopolysaccharide induced hyperalgesia by suppression of microglia but not astrocytes.

    PubMed

    Yoon, S-Y; Patel, D; Dougherty, P M

    2012-09-27

    Systemic injection of lipopolysaccharide (LPS) induces a robust immune response as well as thermal and mechanical hyperalgesia. Spinal and peripheral glial cells have been implicated as important mediators in this hyperalgesia but the specific contributions of microglia versus astrocytes are not entirely clear. To better define these mechanisms, this study examined the febrile response, nociceptive sensitivity, glial cell reactivity and cytokine production in the dorsal root ganglion (DRG) and spinal cord in rats following systemic treatment with LPS and the effects of minocycline in countering these responses. Intraperitoneal LPS injection resulted in an increase in core body temperature and produced hyperalgesia to heat and mechanical stimuli. Western blot studies revealed increased expression of microgial cell, macrophage and satellite cell markers in DRG and microglial and astrocyte markers in spinal cord following LPS treatment. Real-time RT-PCR indicated that LPS treatment increased cytokine mRNA expression levels in both the DRG and the spinal cord. Minocycline suppressed all LPS-induced behavioral effects but not the febrile response. Moreover, minocycline prevented LPS-induced microglia/macrophage activation and cytokine responses in spinal cord and DRG, but did not affect the activation of astrocytes/satellite cells. These data demonstrate that LPS-induced changes in nociceptive sensitivity are likely mediated by activation of microglial cells and/or macrophages in the spinal cord and DRG.

  19. Bradykinin is involved in hyperalgesia induced by Bothrops jararaca venom.

    PubMed

    Chacur, M; Picolo, G; Teixeira, C F P; Cury, Y

    2002-07-01

    Bradykinin is involved in hyperalgesia (pain hypersensitivity) induced by Bothrops jararaca venom-intraplantar injection of B. jararaca venom (5microg/paw) in rats caused hyperalgesia, which peaked 1h after venom injection. This phenomenon was not modified by promethazine (H(1) receptor antagonist), methysergide (5-HT receptor antagonist), guanethidine (sympathetic function inhibitor), anti-TNF-alpha or anti-interleukin-1 antibodies or by the chelating agent CaNa(2)EDTA. Venom-induced hyperalgesia was blocked by the bradykinin B(2) receptor antagonist HOE 140. On the other hand, des-Arg(9), [Leu(8)]-bradykinin, a bradykinin B(1) receptor antagonist, did not modify the hyperalgesic response. These results suggest that bradykinin, acting on B(2) receptor, is a mediator of hyperalgesia induced by B. jararaca venom.

  20. Nuclear factor-kappa B mediates TRPV4-NO pathway involved in thermal hyperalgesia following chronic compression of the dorsal root ganglion in rats.

    PubMed

    Wang, Chao; Ning, Li-Ping; Wang, Yong-Hui; Zhang, Yang; Ding, Xin-Li; Ge, Hong-You; Arendt-Nielsen, Lars; Yue, Shou-Wei

    2011-08-01

    The aim of this study was to test the hypothesis that nuclear factor-kappa B (NF-κB) is involved in TRPV4-NO pathway in thermal hyperalgesia following chronic compression of the dorsal root ganglion (DRG) (the procedure hereafter termed CCD) in rat. Intrathecal administration of two NF-κB inhibitors, pyrrolidine dithiocarbamate (PDTC; 10(-1) to 10(-2)M) and BAY (100-50 μM), both induced significantly dose-dependent increase in the paw withdrawal latency (PWL) and decrease in nitric oxide (NO) content in DRG when compared with control rats. Pretreatment with 4α-phorbol 12,13-didecanoate (4α-PDD, transient receptor potential vanilloid 4 (TRPV4) synthetic activator, 1 nm) attenuated the suppressive effects of PDTC (10(-1)M) and BAY (100 μM) on CCD-induced thermal hyperalgesia and NO production. In addition, Western blot analysis indicated that CCD rats exhibited nuclear NF-κB protein expression and low levels of cytoplasmic inhibitory-kappa B (I-κB) expression; the increase in NF-κB expression and decrease in I-κB expression were reversed after intrathecal injection of PDTC. In conclusion, our data suggested that NF-κB could be involved in TRPV4-NO pathway in CCD-induced thermal hyperalgesia.

  1. Induction of Hyperalgesia in Pigs through Blocking Low Hydraulic Resistance Channels and Reduction of the Resistance through Acupuncture: A Mechanism of Action of Acupuncture

    PubMed Central

    Zhang, Wei-Bo; Xu, Yi-Hui; Tian, Yu-Ying; Li, Hong; Wang, Guang-Jun; Huang, Tao; Jia, Shu-Yong

    2013-01-01

    According to the classic theory of Chinese medicine, pain is due to the blockage in meridian channels, and acupuncture was invented to treat pain by “dredging” the channels. To test the theory, a hyperalgesia model was made by injecting hydrogel into low hydraulic resistance channel (LHRC) in 12 anaesthetized minipigs. Tail-flick threshold and ear-flick threshold were measured using a thermal radiation dolorimeter, and relative flick threshold (RFT) was calculated. Hydraulic resistance (HR) was measured with a biological HR measuring instrument on low HR points on LHRC and on control points with higher HR located outside LHRC; readings were recorded before, during, and after acupuncture treatment. RFT decreased after blocking the LRHC and was still significantly decreased 2 days and 4 days afterwards. No significant changes occurred when injecting saline into the same points or injecting gel into points outside the channel. Subsequent acupuncture reduced HR on LRHC along meridians but had no significant effect on sites with higher HR located outside LHRC. One of the mechanisms of action of acupuncture treatment for chronic pain may be that acupuncture affects peripheral tissue by reducing the HR in LHRC along meridians, improving the flow of interstitial fluid and removing algogenic substances and thereby relieving pain. PMID:23997798

  2. Fatiguing exercise enhances hyperalgesia to muscle inflammation.

    PubMed

    Sluka, Kathleen A; Rasmussen, Lynn A

    2010-02-01

    Since many people with chronic fatigue present with pain and many people with chronic pain present with fatigue, we tested if fatigue would enhance the response to pain in male and female mice. We further tested for the activation of brainstem nuclei by the fatigue task using c-fos as a marker. Fatigue was induced by having mice spontaneously run in running wheel for 2h. Carrageenan (0.03%) was injected into the gastrocnemius muscle either 2h before or 2h after the fatigue task. The mechanical sensitivity of the paw (von Frey filaments), muscle (tweezers), grip force and running wheel activity was assessed before and 24h after injection of carrageenan. Both male and female mice that performed the fatigue task, either before or after intramuscular injection of carrageenan, showed an enhanced mechanical sensitivity of the paw, but not the muscle. Ovariectomized mice showed a similar response to male mice. There was a decrease in running wheel activity after carrageenan injection, but no change in grip force suggesting that mice had no deficit in motor performance induced by the carrageenan. C-fos expression was observed in the nucleus raphe pallidus, obscurus, and magnus after the fatigue task suggesting an increased activity in the raphe nuclei in response to the fatigue task. Therefore, widespread hyperalgesia is enhanced by the fatigue response but not hyperalgesia at the site of insult. We suggest that this effect is sex-dependent and involves mechanisms in the brainstem to result in an enhanced hyperalgesia.

  3. 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.

  4. 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

  5. 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

  6. Placebo manipulations reduce hyperalgesia in neuropathic pain.

    PubMed

    Petersen, Gitte Laue; Finnerup, Nanna Brix; Nørskov, Kathrine Næsted; Grosen, Kasper; Pilegaard, Hans K; Benedetti, Fabrizio; Price, Donald D; Jensen, Troels Staehelin; Vase, Lene

    2012-06-01

    Several studies have shown that placebo analgesia effects can be obtained in healthy volunteers, as well as patients suffering from acute postoperative pain and chronic pain conditions such as irritable bowel syndrome. However, it is unknown whether placebo analgesia effects can be elicited in chronic pain conditions with a known pathophysiology such as a nerve injury. Nineteen patients who had developed neuropathic pain after thoracotomy were exposed to a placebo manipulation in which they received either open or hidden administrations of lidocaine. Before the treatment, the patients rated their levels of spontaneous pain and expected pain and completed a questionnaire on their emotional feelings (Positive Affect Negative Affect Schedule) and went through quantitative sensory testing of evoked pain (brush and cold allodynia, heat pain tolerance, area of pinprick hyperalgesia, wind-up-like pain after pinprick stimulation). The placebo manipulation significantly reduced the area of pinprick hyperalgesia (P=.027), and this placebo effect was significantly related to low levels of negative affect (P=.008; R(2)=0.362) but not to positive affect or expected pain levels. No placebo effect was observed in relation to spontaneous pain or evoked pain, which is most likely due to low pain levels resulting in floor effects. This is the first study to demonstrate a placebo effect in neuropathic pain. The possible mechanisms underlying the placebo effects in hyperalgesia are discussed, and implications for treatment are outlined.

  7. Hyperalgesia induced in the rat by the amino-terminal octapeptide of nerve growth factor.

    PubMed Central

    Taiwo, Y O; Levine, J D; Burch, R M; Woo, J E; Mobley, W C

    1991-01-01

    Nerve growth factor (NGF) in the mouse submandibular gland undergoes cleavage of its amino-terminal octapeptide when salivation is induced by epinephrine. The significance of this event is uncertain; cleaved NGF demonstrates bioactivity and no function has been attributed to the octapeptide produced (NGF-OP; Ser-Ser-Thr-His-Pro-Val-Phe-His). Enzyme inhibition studies indicating structural relatedness of NGF-OP and bradykinin (BK) prompted us to determine whether NGF-OP would elicit BK-like actions. We found that like BK, NGF-OP induced a decrease in mechanical nociceptive threshold (i.e., produced hyperalgesia) in the hairy skin of the rat. This effect was dose-dependent and sequence-specific; like BK it was attenuated by sympathectomy and indomethacin pretreatment. However, NGF-OP actions appeared to be distinct from those for BK in that tissue injury was required for NGF-OP to induce hyperalgesia. Furthermore, we found no evidence that NGF-OP bound to or activated BK receptors. Our data indicate that NGF-OP is a distinct mediator of hyperalgesia. We suggest that NGF-OP alters pain threshold in the injured target regions of NGF-responsive neurons. PMID:1647026

  8. Standardized Aqueous Tribulus terristris (nerunjil) extract attenuates hyperalgesia in experimentally induced diabetic neuropathic pain model: role of oxidative stress and inflammatory mediators.

    PubMed

    Ranjithkumar, Ravichandran; Prathab Balaji, S; Balaji, Bhaskar; Ramesh, R V; Ramanathan, Muthiah

    2013-11-01

    The present study aimed to evaluate standardized aqueous Tribulus terristris (nerunjil) extract on the pain threshold response in streptozotocin (STZ)-induced diabetic neuropathic pain model in rats. After a single injection of STZ (40 mg/kg; i.p.), Wistar male rats were tested by the thermal and chemical-induced pain models. Diabetic rats exhibited significant hyperalgesia, and these rats were left untreated for the first four weeks. Thereafter, treatment was initiated and continued up to week-8. All the rats except the vehicle-treated group received insulin 5 IU/kg/day to maintain plasma glucose levels. Treatment with nerunjil (100 and 300 mg/kg; p.o.) for 4 weeks significantly attenuated the nociception in behavioural models. Nerunjil also inhibited the tumour necrosis factor-α and interleukin-1 beta levels. The effect of nerunjil (300 mg/kg) is comparable to the standard drug Pregabalin (100 mg/kg). Nerunjil increased the superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and decreased the lipid peroxide levels in dose-dependent manner. Insulin alone-treated rats failed to attenuate hyperalgesic response. In comparison to insulin alone-treated rats, nerunjil exhibited significant increase in the pain threshold response. It could be concluded that in controlled diabetic states, nerunjil attenuated the neuropathic pain through modulation of oxidative stress and inflammatory cytokine release.

  9. 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

  10. Opioid-induced hyperalgesia: is it clinically relevant for the treatment of pain patients?

    PubMed

    Raffa, Robert B; Pergolizzi, Joseph V

    2013-09-01

    There is a curious and paradoxic phenomenon, reliably demonstrated in animal models, that consists of an increased sensitivity to pain that is apparently induced by the very opioid drugs used to ameliorate the pain. This phenomenon is termed "opioid-induced hyperalgesia." Whether opioid-induced hyperalgesia occurs in humans, and, if so, to what extent and consequence, is far less established. This is a critical question for attempting to treat pain. If opioid-induced hyperalgesia develops in a patient, it would masquerade as tolerance (because the clinical effectiveness of the opioid would be diminished), yet the appropriate clinical adjustment would be precisely the opposite to that of tolerance. It would be to decrease, rather than increase, the dose of opioid. We review the evidence, particularly the clinical evidence, about opioid-induced hyperalgesia and the postulated mechanisms. We conclude that given the clinical ramifications, opioid-induced hyperalgesia is one of the most understudied important aspects of opioid research.

  11. P2X3 and TRPV1 functionally interact and mediate sensitization of trigeminal sensory neurons

    PubMed Central

    Saloman, Jami L.; Chung, Man-Kyo; Ro, Jin Y.

    2012-01-01

    Musculoskeletal pain conditions, particularly those associated with temporomandibular joint and muscle disorders (TMD) affect a large percentage of the population. Identifying mechanisms underlying hyperalgesia could contribute to the development of new treatment strategies for the management of TMD and other muscle pain conditions. In this study, we provide evidence of functional interactions between two ligand-gated channels, P2X3 and TRPV1, in trigeminal sensory neurons, and propose that the interactions serve as an underlying mechanism for the development of mechanical hyperalgesia. Mechanical sensitivity of the masseter muscle was assessed in lightly anesthetized rats via an electronic anesthesiometer (Ro et al., 2009). Direct intramuscular injection of a selective P2X3 agonist, αβmeATP, induced a dose- and time-dependent hyperalgesia. Mechanical sensitivity in the contralateral muscle was unaffected suggesting local P2X3 mediate the hyperalgesia. Anesthetizing the overlying skin had no effect on αβmeATP-induced hyperalgesia confirming the contribution of P2X3 from muscle. Importantly, the αβmeATP-induced hyperalgesia was prevented by pretreatment of the muscle with a TRPV1 antagonist, AMG9810. P2X3 was co-expressed with TRPV1 in masseter muscle afferents confirming the possibility for intracellular interactions. Additionally, in a subpopulation of P2X3/TRPV1 positive neurons, capsaicin-induced Ca2+ transients were significantly amplified following P2X3 activation. Finally, activation of P2X3 induced phosphorylation of serine, but not threonine, residues in TRPV1 in trigeminal ganglia cultures. Significant phosphorylation was observed at 15 min, the time point at which behavioral hyperalgesia was prominent. Previously, activation of either P2X3 or TRPV1 had been independently implicated in the development of mechanical hyperalgesia. Our data propose P2X3 and TRPV1 interact in a facilitatory manner, which could contribute to the peripheral sensitization

  12. P2X₃ and TRPV1 functionally interact and mediate sensitization of trigeminal sensory neurons.

    PubMed

    Saloman, J L; Chung, M-K; Ro, J Y

    2013-03-01

    Musculoskeletal pain conditions, particularly those associated with temporomandibular disorders (TMD) affect a large percentage of the population. Identifying mechanisms underlying hyperalgesia could contribute to the development of new treatment strategies for the management of TMD and other muscle pain conditions. In this study, we provide evidence of functional interactions between two ligand-gated channels, P2X₃ and transient receptor potential V1 (TRPV1), in trigeminal sensory neurons, and propose that the interactions serve as an underlying mechanism for the development of mechanical hyperalgesia. Mechanical sensitivity of the masseter muscle was assessed in lightly anesthetized rats via an electronic anesthesiometer (Ro et al., 2009). Direct intramuscular injection of a selective P2X₃ agonist, alpha,beta-methylene adenosine triphosphate (αβmeATP), induced a dose- and time-dependent hyperalgesia. Mechanical sensitivity in the contralateral muscle was unaffected suggesting local P2X₃ mediate hyperalgesia. Anesthetizing the overlying skin had no effect on αβmeATP-induced hyperalgesia confirming the contribution of P2X₃ from the muscle. Importantly, the αβmeATP-induced hyperalgesia was prevented by pretreatment of the muscle with a TRPV1 antagonist, AMG9810. P2X₃ was co-expressed with TRPV1 in the masseter muscle afferents confirming the possibility for intracellular interactions. Additionally, in a subpopulation of P2Xv/TRPV1 positive neurons, capsaicin-induced Ca(2+) transients were significantly amplified following P2X₃ activation. Finally, activation of P2X₃ induced phosphorylation of serine, but not threonine, residues in TRPV1 in trigeminal ganglia cultures. Significant phosphorylation was observed at 15 min, the time point at which behavioral hyperalgesia was prominent. Previously, activation of either P2X₃ or TRPV1 had been independently implicated in the development of mechanical hyperalgesia. Our data propose P2X₃ and TRPV1

  13. Ca2+/calmodulin-dependent protein kinase II alpha is required for the initiation and maintenance of opioid-induced hyperalgesia.

    PubMed

    Chen, Yan; Yang, Cheng; Wang, Zaijie Jim

    2010-01-01

    Repeated administration of opioids not only leads to tolerance and dependence, but also results in nociceptive enhancement called opioid-induced hyperalgesia (OIH). Nociceptive mediators involved in OIH generation remain poorly understood. In the present study, we tested the hypothesis that Ca(2+)/calmodulin-depent protein kinase II (CaMKIIalpha) is critical for OIH. Opioid-induced hyperalgesia was produced by repeated morphine administration or pellet implantation in mice. Correlating with the development of tactile allodynia and thermal hyperalgesia, spinal CaMKIIalpha activity was significantly increased in OIH. KN93, a CaMKII inhibitor, dose- and time-dependently reversed OIH and CaMKII activation without impairing locomotor coordination. To elucidate the specific CaMKII isoform involved, we targeted CaMKIIalpha by using small interfering RNA and demonstrated that knockdown of spinal CaMKIIalpha attenuated OIH. Furthermore, morphine failed to induce OIH in CaMKIIalpha(T286A) point mutant mice, although wild-type littermate mice developed robust OIH after repeated treatments with morphine. These data implicate, for the first time, an essential role of CaMKIIalpha as a cellular mechanism leading to and maintaining opioid-induced hyperalgesia.

  14. Contributions of spinal D-amino acid oxidase to chronic morphine-induced hyperalgesia.

    PubMed

    Ma, Shuai; Li, Xin-Yan; Gong, Nian; Wang, Yong-Xiang

    2015-12-10

    Spinal D-amino acid oxidase (DAAO) is an FAD-dependent peroxisomal flavoenzyme which mediates the conversion of neutral and polar D-amino acids (including D-serine) to the corresponding α-keto acids, and simultaneously produces hydrogen peroxide and ammonia. This study has aimed to explore the potential contributions of spinal DAAO and its mediated hydrogen peroxide/D-serine metabolism to the development of morphine-induced hyperalgesia. Bi-daily subcutaneous injections of morphine to mice over 7 days induced thermal hyperalgesia as measured by both the hot-plate and tail-immersion tests, and spinal astroglial activation with increased spinal gene expression of DAAO, glial fibrillary acidic protein (GFAP) and pro-inflammatory cytokines (interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α)). Subcutaneous injections of the potent DAAO inhibitor CBIO (5-chloro-benzo[D]isoxazol-3-ol) prevented and reversed the chronic morphine-induced hyperalgesia. CBIO also inhibited both astrocyte activation and the expression of pro-inflammatory cytokines. Intrathecal injection of the hydrogen peroxide scavenger PBN (phenyl-N-tert-butylnitrone) and of catalase completely reversed established morphine hyperalgesia, whereas subcutaneous injections of exogenous D-serine failed to alter chronic morphine-induced hyperalgesia. These results provided evidence that spinal DAAO and its subsequent production of hydrogen peroxide rather than the D-serine metabolism contributed to the development of morphine-induced hyperalgesia.

  15. Opioid induced hyperalgesia in anesthetic settings.

    PubMed

    Lee, Hyeon Jeong; Yeomans, David C

    2014-11-01

    Pain is difficult to investigate and difficult to treat, in part, because of problems in quantification and assessment. The use of opioids, combined with classic anesthetics to maintain hemodynamic stability by controlling responses to intraoperative painful events has gained significant popularity in the anesthetic field. However, several side effects profiles concerning perioperative use of opioid have been published. Over the past two decades, many concerns have arisen with respect to opioid-induced hyperalgesia (OIH), which is the paradoxical effect wherein opioid usage may decrease pain thresholds and increase atypical pain unrelated to the original, preexisting pain. This brief review focuses on the evidence, mechanisms, and modulatory and pharmacologic management of OIH in order to elaborate on the clinical implication of OIH.

  16. 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

  17. 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.

  18. The impact of opioid-induced hyperalgesia for postoperative pain.

    PubMed

    Koppert, Wolfgang; Schmelz, Martin

    2007-03-01

    Clinical evidence suggests that--besides their well known analgesic activity - opioids can increase rather than decrease sensitivity to noxious stimuli. Based on the observation that opioids can activate pain inhibitory and pain facilitatory systems, this pain hypersensitivity has been attributed to a relative predominance of pronociceptive mechanisms. Acute receptor desensitization via uncoupling of the receptor from G-proteins, upregulation of the cAMP pathway, activation of the N-methyl-D-aspartate (NMDA)-receptor system, as well as descending facilitation, have been proposed as potential mechanisms underlying opioid-induced hyperalgesia. Numerous reports exist demonstrating that opioid-induced hyperalgesia is observed both in animal and human experimental models. Brief exposures to micro-receptor agonists induce long-lasting hyperalgesic effects for days in rodents, and also in humans large-doses of intraoperative micro-receptor agonists were found to increase postoperative pain and morphine consumption. Furthermore, the prolonged use of opioids in patients is often associated with a requirement for increasing doses and the development of abnormal pain. Successful strategies that may decrease or prevent opioid-induced hyperalgesia include the concomitant administration of drugs like NMDA-antagonists, alpha2-agonists, or non-steroidal anti-inflammatory drugs (NSAIDs), opioid rotation or combinations of opioids with different receptor/selectivity.

  19. Calcium-mediated mechanisms of cystic expansion

    PubMed Central

    Abdul-Majeed, Shakila; Nauli, Surya M.

    2010-01-01

    In this review, we will discuss several well-accepted signaling pathways toward calcium-mediated mechanisms of cystic expansion. The second messenger calcium ion has contributed to a vast diversity of signal transduction pathways. We will dissect calcium signaling as a possible mechanism that contributes to renal cyst formation. Because cytosolic calcium also regulates an array of signaling pathways, we will first discuss cilia-induced calcium fluxes, followed by Wnt signaling that has attributed to much-discussed planar cell polarity. We will then look at the relationship between cytosolic calcium and cAMP as one of the most important aspects of cyst progression. The signaling of cAMP on MAPK and mTOR will also be discussed. We infer that while cilia-induced calcium fluxes may be the initial signaling messenger for various cellular pathways, no single signaling mediator or pathway is implicated exclusively in the progression of the cystic expansion. PMID:20932898

  20. [Opioid-induced hyperalgesia. Pathophysiology and clinical relevance].

    PubMed

    Koppert, W

    2004-05-01

    Opioids are the drugs of choice for the treatment of moderate to severe acute and chronic pain. However, clinical evidence suggests that opioids can elicit increased sensitivity to noxious stimuli suggesting that administration of opioids can activate both pain inhibitory and pain facilitatory systems. Acute receptor desensitization via uncoupling of the receptor from G-proteins, up-regulation of the cAMP pathway, activation of the N-methyl-D-aspartate (NMDA) receptor system, as well as descending facilitation, have been proposed as potential mechanisms underlying opioid-induced hyperalgesia. Numerous reports exist demonstrating that opioid-induced hyperalgesia is observed both in animal and human experimental models. Brief exposures to micro-receptor agonists induce long-lasting hyperalgesic effects for days, which might by reflected by clinical observations that large doses of intraoperative micro-receptor agonists increased postoperative pain and morphine consumption. Furthermore, the prolonged use of opioids in patients often requires increasing doses and may be accompanied by the development of abnormal pain. Successful strategies that may decrease or prevent opioid-induced hyperalgesia include the concomitant administration of drugs like NMDA-antagonists, alpha(2)-agonists, or non-steroidal anti-inflammatory drugs (NSAIDs), opioid rotation or combinations of opioids with different receptor selectivity.

  1. Carbamazepine Withdrawal-induced Hyperalgesia in Chronic Neuropathic Pain.

    PubMed

    Ren, Zhenyu; Yang, Bing; Yang, Bin; Shi, Le; Sun, Qing-Li; Sun, A-Ping; Lu, Lin; Liu, Xiaoguang; Zhao, Rongsheng; Zhai, Suodi

    2015-11-01

    Combined pharmacological treatments are the most used approach for neuropathic pain. Carbamazepine, an antiepileptic agent, is generally used as a third-line treatment for neuropathic pain and can be considered an option only when patients have not responded to the first- and second-line medications. In the case presented herein, a patient with neuropathic pain was treated using a combined pharmacological regimen. The patient's pain deteriorated, despite increasing the doses of opioids, when carbamazepine was discontinued, potentially because carbamazepine withdrawal disrupted the balance that was achieved by the multifaceted pharmacological regimen, thus inducing hyperalgesia. Interestingly, when carbamazepine was prescribed again, the patient's pain was successfully managed. Animal research has reported that carbamazepine can potentiate the analgesic effectiveness of morphine in rodent models of neuropathic pain and postoperative pain. This clinical case demonstrates that carbamazepine may have a synergistic effect on the analgesic effectiveness of morphine and may inhibit or postpone opioid-induced hyperalgesia. We postulate that a probable mechanism of action of carbamazepine may involve -aminobutyric acid-ergic potentiation and the interruption of glutamatergic function via N-methyl-D-aspartate receptors. Further research is warranted to clarify the analgesic action of carbamazepine and its potential use for the prevention of opioid-induced hyperalgesia in chronic neuropathic pain patients.

  2. Perspective and prejudice: antecedents and mediating mechanisms.

    PubMed

    Dovidio, John F; ten Vergert, Marleen; Stewart, Tracie L; Gaertner, Samuel L; Johnson, James D; Esses, Victoria M; Riek, Blake M; Pearson, Adam R

    2004-12-01

    The present work investigated mechanisms by which Whites' prejudice toward Blacks can be reduced (Study 1) and explored how creating a common ingroup identity can reduce prejudice by promoting these processes (Study 2). In Study 1, White participants who viewed a videotape depicting examples of racial discrimination and who imagined the victim's feelings showed greater decreases in prejudice toward Blacks than did those in the objective and no instruction conditions. Among the potential mediating affective and cognitive variables examined, reductions in prejudice were mediated primarily by feelings associated with perceived injustice. In Study 2, an intervention designed to increase perceptions of a common group identity before viewing the videotape, reading that a terrorist threat was directed at all Americans versus directed just at White Americans, also reduced prejudice toward Blacks through increases in feelings of injustice. PMID:15536238

  3. Importance of CRF receptor-mediated mechanisms of the bed nucleus of the stria terminalis in the processing of anxiety and pain.

    PubMed

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

    2014-10-01

    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.

  4. 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

  5. Role of Corticotropin-releasing Factor Signaling in Stress-related Alterations of Colonic Motility and Hyperalgesia

    PubMed Central

    Taché, Yvette; Million, Mulugeta

    2015-01-01

    The corticotropin-releasing factor (CRF) signaling systems encompass CRF and the structurally related peptide urocortin (Ucn) 1, 2, and 3 along with 2 G-protein coupled receptors, CRF1 and CRF2. CRF binds with high and moderate affinity to CRF1 and CRF2 receptors, respectively while Ucn1 is a high-affinity agonist at both receptors, and Ucn2 and Ucn3 are selective CRF2 agonists. The CRF systems are expressed in both the brain and the colon at the gene and protein levels. Experimental studies established that the activation of CRF1 pathway in the brain or the colon recaptures cardinal features of diarrhea predominant irritable bowel syndrome (IBS) (stimulation of colonic motility, activation of mast cells and serotonin, defecation/watery diarrhea, and visceral hyperalgesia). Conversely, selective CRF1 antagonists or CRF1/CRF2 antagonists, abolished or reduced exogenous CRF and stress-induced stimulation of colonic motility, defecation, diarrhea and colonic mast cell activation and visceral hyperalgesia to colorectal distention. By contrast, the CRF2 signaling in the colon dampened the CRF1 mediated stimulation of colonic motor function and visceral hyperalgesia. These data provide a conceptual framework that sustained activation of the CRF1 system at central and/or peripheral sites may be one of the underlying basis of IBS-diarrhea symptoms. While targeting these mechanisms by CRF1 antagonists provided a relevant novel therapeutic venue, so far these promising preclinical data have not translated into therapeutic use of CRF1 antagonists. Whether the existing or newly developed CRF1 antagonists will progress to therapeutic benefits for stress-sensitive diseases including IBS for a subset of patients is still a work in progress. PMID:25611064

  6. 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

  7. 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.

  8. 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

  9. HCN1 Channels as Targets for Anesthetic and Nonanesthetic Propofol Analogs in the Amelioration of Mechanical and Thermal Hyperalgesia in a Mouse Model of Neuropathic Pain

    PubMed Central

    Tibbs, Gareth R.; Rowley, Thomas J.; Sanford, R. Lea; Herold, Karl F.; Proekt, Alex; Hemmings, Hugh C.; Andersen, Olaf S.; Flood, Pamela D.

    2013-01-01

    Chronic pain after peripheral nerve injury is associated with afferent hyperexcitability and upregulation of hyperpolarization-activated, cyclic nucleotide-regulated (HCN)–mediated IH pacemaker currents in sensory neurons. HCN channels thus constitute an attractive target for treating chronic pain. HCN channels are ubiquitously expressed; analgesics targeting HCN1-rich cells in the peripheral nervous system must spare the cardiac pacemaker current (carried mostly by HCN2 and HCN4) and the central nervous system (where all four isoforms are expressed). The alkylphenol general anesthetic propofol (2,6-di-iso-propylphenol) selectively inhibits HCN1 channels versus HCN2–HCN4 and exhibits a modest pharmacokinetic preference for the periphery. Consequently, we hypothesized that propofol, and congeners, should be antihyperalgesic. Alkyl-substituted propofol analogs have different rank-order potencies with respect to HCN1 inhibition, GABAA receptor (GABAA-R) potentiation, and general anesthesia. Thus, 2,6- and 2,4-di-tertbutylphenol (2,6- and 2,4-DTBP, respectively) are more potent HCN1 antagonists than propofol, whereas 2,6- and 2,4-di-sec-butylphenol (2,6- and 2,4-DSBP, respectively) are less potent. In contrast, DSBPs, but not DTBPs, enhance GABAA-R function and are general anesthetics. 2,6-DTBP retained propofol’s selectivity for HCN1 over HCN2–HCN4. In a peripheral nerve ligation model of neuropathic pain, 2,6-DTBP and subhypnotic propofol are antihyperalgesic. The findings are consistent with these alkylphenols exerting analgesia via non-GABAA-R targets and suggest that antagonism of central HCN1 channels may be of limited importance to general anesthesia. Alkylphenols are hydrophobic, and thus potential modifiers of lipid bilayers, but their effects on HCN channels are due to direct drug-channel interactions because they have little bilayer-modifying effect at therapeutic concentrations. The alkylphenol antihyperalgesic target may be HCN1 channels in the

  10. 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

  11. TRPA1 contributes to capsaicin-induced facial cold hyperalgesia in rats.

    PubMed

    Honda, Kuniya; Shinoda, Masamichi; Furukawa, Akihiko; Kita, Kozue; Noma, Noboru; Iwata, Koichi

    2014-12-01

    Orofacial cold hyperalgesia is known to cause severe persistent pain in the face following trigeminal nerve injury or inflammation, and transient receptor potential (TRP) vanilloid 1 (TRPV1) and TRP ankylin 1 (TRPA1) are thought to be involved in cold hyperalgesia. However, how these two receptors are involved in cold hyperalgesia is not fully understood. To clarify the mechanisms underlying facial cold hyperalgesia, nocifensive behaviors to cold stimulation, the expression of TRPV1 and TRPA1 in trigeminal ganglion (TG) neurons, and TG neuronal excitability to cold stimulation following facial capsaicin injection were examined in rats. The head-withdrawal reflex threshold (HWRT) to cold stimulation of the lateral facial skin was significantly decreased following facial capsaicin injection. This reduction of HWRT was significantly recovered following local injection of TRPV1 antagonist as well as TRPA1 antagonist. Approximately 30% of TG neurons innervating the lateral facial skin expressed both TRPV1 and TRPA1, and about 64% of TRPA1-positive neurons also expressed TRPV1. The TG neuronal excitability to noxious cold stimulation was significantly increased following facial capsaicin injection and this increase was recovered by pretreatment with TRPA1 antagonist. These findings suggest that TRPA1 sensitization via TRPV1 signaling in TG neurons is involved in cold hyperalgesia following facial skin capsaicin injection.

  12. Molecular mechanisms regulating CD13-mediated adhesion

    PubMed Central

    Ghosh, Mallika; Gerber, Claire; Rahman, M Mamunur; Vernier, Kaitlyn M; Pereira, Flavia E; Subramani, Jaganathan; Caromile, Leslie A; Shapiro, Linda H

    2014-01-01

    CD13/Aminopeptidase N is a transmembrane metalloproteinase that is expressed in many tissues where it regulates various cellular functions. In inflammation, CD13 is expressed on myeloid cells, is up-regulated on endothelial cells at sites of inflammation and mediates monocyte/endothelial adhesion by homotypic interactions. In animal models the lack of CD13 alters the profiles of infiltrating inflammatory cells at sites of ischaemic injury. Here, we found that CD13 expression is enriched specifically on the pro-inflammatory subset of monocytes, suggesting that CD13 may regulate trafficking and function of specific subsets of immune cells. To further dissect the mechanisms regulating CD13-dependent trafficking we used the murine model of thioglycollate-induced sterile peritonitis. Peritoneal monocytes, macrophages and dendritic cells were significantly decreased in inflammatory exudates from global CD13KO animals when compared with wild-type controls. Furthermore, adoptive transfer of wild-type and CD13KO primary myeloid cells, or wild-type myeloid cells pre-treated with CD13-blocking antibodies into thioglycollate-challenged wild-type recipients demonstrated fewer CD13KO or treated cells in the lavage, suggesting that CD13 expression confers a competitive advantage in trafficking. Similarly, both wild-type and CD13KO cells were reduced in infiltrates in CD13KO recipients, confirming that both monocytic and endothelial CD13 contribute to trafficking. Finally, murine monocyte cell lines expressing mouse/human chimeric CD13 molecules demonstrated that the C-terminal domain of the protein mediates CD13 adhesion. Therefore, this work verifies that the altered inflammatory trafficking in CD13KO mice is the result of aberrant myeloid cell subset trafficking and further defines the molecular mechanisms underlying this regulation. PMID:24627994

  13. [The clinical relevance of opioid-induced hyperalgesia remains unresolved].

    PubMed

    Sørensen, Jakob; Sjøgren, Per

    2011-03-28

    Opioids are widely used as analgesics in chronic pain of malignant as well as non-malignant origin. During opioid treatment, pain is occasionally worsened. This could be due to progression of the disease or tolerance or opioid-induced hyperalgesia (OIH). The present article summarizes the preclinical and clinical data in support of the existence of OIH. Further, possible mechanisms and potential treatments are outlined. We conclude that only a few clinical studies on OIH are available. However, a growing body of experimental data supports the presence of OIH in clinical settings. Diagnostic tools for assessment of OIH have yet to be developed.

  14. Secondary Hyperalgesia Phenotypes Exhibit Differences in Brain Activation during Noxious Stimulation

    PubMed Central

    Werner, Mads Utke; Mårtensson, Johan; Larsson, Henrik B. W.; Dahl, Jørgen Berg

    2015-01-01

    Noxious stimulation of the skin with either chemical, electrical or heat stimuli leads to the development of primary hyperalgesia at the site of injury, and to secondary hyperalgesia in normal skin surrounding the injury. Secondary hyperalgesia is inducible in most individuals and is attributed to central neuronal sensitization. Some individuals develop large areas of secondary hyperalgesia (high-sensitization responders), while others develop small areas (low-sensitization responders). The magnitude of each area is reproducible within individuals, and can be regarded as a phenotypic characteristic. To study differences in the propensity to develop central sensitization we examined differences in brain activity and anatomy according to individual phenotypical expression of secondary hyperalgesia by magnetic resonance imaging. Forty healthy volunteers received a first-degree burn-injury (47°C, 7 min, 9 cm2) on the non-dominant lower-leg. Areas of secondary hyperalgesia were assessed 100 min after the injury. We measured neuronal activation by recording blood-oxygen-level-dependent-signals (BOLD-signals) during mechanical noxious stimulation before burn injury and in both primary and secondary hyperalgesia areas after burn-injury. In addition, T1-weighted images were used to measure differences in gray-matter density in cortical and subcortical regions of the brain. We found significant differences in neuronal activity between high- and low-sensitization responders at baseline (before application of the burn-injury) (p < 0.05). After the burn-injury, we found significant differences between responders during noxious stimulation of both primary (p < 0.01) and secondary hyperalgesia (p ≤ 0.04) skin areas. A decreased volume of the right (p = 0.001) and left caudate nucleus (p = 0.01) was detected in high-sensitization responders in comparison to low-sensitization responders. These findings suggest that brain-structure and neuronal activation to noxious stimulation

  15. Secondary hyperalgesia phenotypes exhibit differences in brain activation during noxious stimulation.

    PubMed

    Asghar, Mohammad Sohail; Pereira, Manuel Pedro; Werner, Mads Utke; Mårtensson, Johan; Larsson, Henrik B W; Dahl, Jørgen Berg

    2015-01-01

    Noxious stimulation of the skin with either chemical, electrical or heat stimuli leads to the development of primary hyperalgesia at the site of injury, and to secondary hyperalgesia in normal skin surrounding the injury. Secondary hyperalgesia is inducible in most individuals and is attributed to central neuronal sensitization. Some individuals develop large areas of secondary hyperalgesia (high-sensitization responders), while others develop small areas (low-sensitization responders). The magnitude of each area is reproducible within individuals, and can be regarded as a phenotypic characteristic. To study differences in the propensity to develop central sensitization we examined differences in brain activity and anatomy according to individual phenotypical expression of secondary hyperalgesia by magnetic resonance imaging. Forty healthy volunteers received a first-degree burn-injury (47 °C, 7 min, 9 cm(2)) on the non-dominant lower-leg. Areas of secondary hyperalgesia were assessed 100 min after the injury. We measured neuronal activation by recording blood-oxygen-level-dependent-signals (BOLD-signals) during mechanical noxious stimulation before burn injury and in both primary and secondary hyperalgesia areas after burn-injury. In addition, T1-weighted images were used to measure differences in gray-matter density in cortical and subcortical regions of the brain. We found significant differences in neuronal activity between high- and low-sensitization responders at baseline (before application of the burn-injury) (p < 0.05). After the burn-injury, we found significant differences between responders during noxious stimulation of both primary (p < 0.01) and secondary hyperalgesia (p ≤ 0.04) skin areas. A decreased volume of the right (p = 0.001) and left caudate nucleus (p = 0.01) was detected in high-sensitization responders in comparison to low-sensitization responders. These findings suggest that brain-structure and neuronal activation to noxious

  16. 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.

  17. 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.

  18. Lateral Hypothalamic Stimulation Reduces Hyperalgesia Through Spinally Descending Orexin-A Neurons in Neuropathic Pain.

    PubMed

    Wardach, Jacob; Wagner, Monica; Jeong, Younhee; Holden, Janean E

    2016-03-01

    No evidence to date shows that lateral hypothalamic (LH) stimulation produces orexin-A-mediated antinociception in the spinal cord dorsal horn (SCDH) in a model of neuropathic pain. We conducted experiments to examine the effect of orexin-A-mediated LH stimulation in female rats with chronic constriction injury (CCI) on thermal hyperalgesia. Rats receiving carbachol into the LH demonstrated antinociception on both the left CCI and right nonligated paws (p < .05). Rats were given carbachol in the LH followed by intrathecal injection of the orexin-1 (OX1) receptor antagonist SB-334867, which blocked LH-induced antinociception compared with control groups (p < .05) in the left paw, but not in the right paw. These findings support the hypothesis that LH stimulation produces antinociception in rats with thermal hyperalgesia from neuropathic pain via an orexin-A connection between the LH and the SCDH. Identification of this pathway may lead to studies using orexins to manage clinical pain.

  19. Role of kinin B2 receptors in opioid-induced hyperalgesia in inflammatory pain in mice.

    PubMed

    Grastilleur, Sébastien; Mouledous, Lionel; Bedel, Jerome; Etcheverry, Jonathan; Bader, Michael; Girolami, Jean-Pierre; Fourcade, Olivier; Frances, Bernard; Minville, Vincent

    2013-03-01

    Postoperative pain management is a clinical challenge that can be complicated by opioid-induced hyperalgesia (OIH). Kinin receptors could mediate both the acute and chronic phases of inflammation and pain. A few recent studies suggest that dynorphin A could maintain neuropathic pain by activating the bradykinin (BK) receptor. Thus, the effect of a single administration of sufentanil (a μ-opioid receptor agonist) was investigated in a model of carrageenan-induced inflammatory pain using three strains of mice, i.e., knockout mice for one kinin receptor, B1R or B2R (B1KO, B2KO), and wild-type C57/BL6J mice (WT) treated with either a B1R (R954) or a B2R antagonist (HOE140) or a KKS inhibitor (aprotinin). Pain was assessed and compared between the different groups using two behavioral tests exploring mechanical (von Frey filaments) and thermal (Hargreaves test) sensitivity. Pretreatment with sufentanil induced a sustained increase in pain sensitivity with a delayed return to baseline values characterizing an OIH in carrageenan-injected mice only. Sufentanil-induced OIH was not observed in B2KO but persisted in B1KO and was blunted by aprotinin and the B2R antagonist only. Collectively, our data indicate that the B2R receptor and BK synthesis or availability are essential peripheral steps in the mechanism leading to OIH in a pain context.

  20. Role of kinin B2 receptors in opioid-induced hyperalgesia in inflammatory pain in mice.

    PubMed

    Grastilleur, Sébastien; Mouledous, Lionel; Bedel, Jerome; Etcheverry, Jonathan; Bader, Michael; Girolami, Jean-Pierre; Fourcade, Olivier; Frances, Bernard; Minville, Vincent

    2013-03-01

    Postoperative pain management is a clinical challenge that can be complicated by opioid-induced hyperalgesia (OIH). Kinin receptors could mediate both the acute and chronic phases of inflammation and pain. A few recent studies suggest that dynorphin A could maintain neuropathic pain by activating the bradykinin (BK) receptor. Thus, the effect of a single administration of sufentanil (a μ-opioid receptor agonist) was investigated in a model of carrageenan-induced inflammatory pain using three strains of mice, i.e., knockout mice for one kinin receptor, B1R or B2R (B1KO, B2KO), and wild-type C57/BL6J mice (WT) treated with either a B1R (R954) or a B2R antagonist (HOE140) or a KKS inhibitor (aprotinin). Pain was assessed and compared between the different groups using two behavioral tests exploring mechanical (von Frey filaments) and thermal (Hargreaves test) sensitivity. Pretreatment with sufentanil induced a sustained increase in pain sensitivity with a delayed return to baseline values characterizing an OIH in carrageenan-injected mice only. Sufentanil-induced OIH was not observed in B2KO but persisted in B1KO and was blunted by aprotinin and the B2R antagonist only. Collectively, our data indicate that the B2R receptor and BK synthesis or availability are essential peripheral steps in the mechanism leading to OIH in a pain context. PMID:23324378

  1. 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

  2. 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

  3. Protective effects of dexmedetomidine combined with flurbiprofen axetil on remifentanil-induced hyperalgesia: A randomized controlled trial

    PubMed Central

    Yu, Zenggui; Wu, Weilan; Wu, Xiaodan; Lei, Hongyi; Gong, Cansheng; Xu, Shiyuan

    2016-01-01

    High dosages of intra-operative remifentanil are associated with opioid-induced hyperalgesia (OIH). The aim of the present study was to investigate the effect of combined dexmedetomidine and flurbiprofen axetil treatment on remifentanil-induced hyperalgesia. Patients with an American Society of Anesthesiologists physical status of I–II who were diagnosed with hysteromyoma and scheduled for laparoscopic assisted vaginal hysterectomy (LAVH) were randomly divided into three groups. Group hyperalgesia (Group H, n=29) received intra-operative remifentanil, Group hyperalgesia and dexmedetomidine (Group HD, n=28) received remifentanil and a continuous infusion of dexmedetomidine, and Group hyperalgesia, dexmedetomidine and flurbiprofen axetil (Group HDF, n=29) received remifentanil, flurbiprofen axetil and dexmedetomidine. Mechanical pain thresholds were measured during the preoperative visit and postoperatively at 1, 6 and 24-h time points. Visual analog scale (VAS) scores, time to analgesic requirement, total sufentanil consumption and side effects were assessed postoperatively. Mechanical pain threshold at the incision site was significantly lower in Group H compared with Groups HD and HDF (both P<0.05), and significantly higher in Group HDF than in Group HD (P<0.05). The area of secondary hyperalgesia at the incision site was greater in Group H than in the other two groups (both P<0.05), and significantly smaller in Group HDF compared with Group HD (P<0.05). VAS scores and total sufentanil consumption were significantly higher in Group H compared with the other two groups (both P<0.05), and were significantly lower in Group HDF compared with Group HD (P<0.05). Dexmedetomidine combined with flurbiprofen axetil exhibits synergetic effects in the prevention of remifentanil-induced hyperalgesia in patients undergoing LAVH. PMID:27698764

  4. Protective effects of dexmedetomidine combined with flurbiprofen axetil on remifentanil-induced hyperalgesia: A randomized controlled trial

    PubMed Central

    Yu, Zenggui; Wu, Weilan; Wu, Xiaodan; Lei, Hongyi; Gong, Cansheng; Xu, Shiyuan

    2016-01-01

    High dosages of intra-operative remifentanil are associated with opioid-induced hyperalgesia (OIH). The aim of the present study was to investigate the effect of combined dexmedetomidine and flurbiprofen axetil treatment on remifentanil-induced hyperalgesia. Patients with an American Society of Anesthesiologists physical status of I–II who were diagnosed with hysteromyoma and scheduled for laparoscopic assisted vaginal hysterectomy (LAVH) were randomly divided into three groups. Group hyperalgesia (Group H, n=29) received intra-operative remifentanil, Group hyperalgesia and dexmedetomidine (Group HD, n=28) received remifentanil and a continuous infusion of dexmedetomidine, and Group hyperalgesia, dexmedetomidine and flurbiprofen axetil (Group HDF, n=29) received remifentanil, flurbiprofen axetil and dexmedetomidine. Mechanical pain thresholds were measured during the preoperative visit and postoperatively at 1, 6 and 24-h time points. Visual analog scale (VAS) scores, time to analgesic requirement, total sufentanil consumption and side effects were assessed postoperatively. Mechanical pain threshold at the incision site was significantly lower in Group H compared with Groups HD and HDF (both P<0.05), and significantly higher in Group HDF than in Group HD (P<0.05). The area of secondary hyperalgesia at the incision site was greater in Group H than in the other two groups (both P<0.05), and significantly smaller in Group HDF compared with Group HD (P<0.05). VAS scores and total sufentanil consumption were significantly higher in Group H compared with the other two groups (both P<0.05), and were significantly lower in Group HDF compared with Group HD (P<0.05). Dexmedetomidine combined with flurbiprofen axetil exhibits synergetic effects in the prevention of remifentanil-induced hyperalgesia in patients undergoing LAVH.

  5. Metformin attenuates hyperalgesia and allodynia in rats with painful diabetic neuropathy induced by streptozotocin.

    PubMed

    Ma, Junxiong; Yu, Hailong; Liu, Jun; Chen, Yu; Wang, Qi; Xiang, Liangbi

    2015-10-01

    Painful diabetic neuropathy is a common complication of diabetes mellitus, which often makes the patients suffer from severe hyperalgesia and allodynia. Thus far, the treatment of painful diabetic neuropathy remains unsatisfactory. Metformin, which is the first-line drug for type-2 diabetes, has been proved to attenuate hyperexcitability in sensory neurons linked to chemotherapy-induced neuropathic pain, highlighting its potential in alleviating pain related with painful diabetic neuropathy. The present study was designed to investigate the potential beneficial effect of metformin on hyperalgesia and allodynia in diabetic rats. The mechanical sensitivity, heat nociception, and cold allodynia were examined. The levels of malondialdehyde, superoxide dismutase, and advanced glycation end-products in the blood were measured. The expression of adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and AMPK target genes were examined in the sciatic nerves of the animals. It was found that metformin was capable of attenuating diabetes-induced mechanical hyperalgesia, heat hyperalgesia and cold allodynia. In addition, metformin was capable of decreasing malondialdehyde and glycation end-products levels in blood, as well as increasing superoxide dismutas activity, indicating the inhibitory effect of metformin against diabetes-induced oxidative stress. Further studies showed that metformin could activate AMPK and increase the AMPK target genes in sciatic nerves in diabetic rats. In conclusion, metformin is able to attenuate diabetes-induced hyperalgesia and allodynia, which might be associated its anti-oxidative effect through AMPK pathway. Metformin might be used as an effective drug, especially with fewer side effects, for abnormal sensation in painful diabetic neuropathy. PMID:26054810

  6. Metformin attenuates hyperalgesia and allodynia in rats with painful diabetic neuropathy induced by streptozotocin.

    PubMed

    Ma, Junxiong; Yu, Hailong; Liu, Jun; Chen, Yu; Wang, Qi; Xiang, Liangbi

    2015-10-01

    Painful diabetic neuropathy is a common complication of diabetes mellitus, which often makes the patients suffer from severe hyperalgesia and allodynia. Thus far, the treatment of painful diabetic neuropathy remains unsatisfactory. Metformin, which is the first-line drug for type-2 diabetes, has been proved to attenuate hyperexcitability in sensory neurons linked to chemotherapy-induced neuropathic pain, highlighting its potential in alleviating pain related with painful diabetic neuropathy. The present study was designed to investigate the potential beneficial effect of metformin on hyperalgesia and allodynia in diabetic rats. The mechanical sensitivity, heat nociception, and cold allodynia were examined. The levels of malondialdehyde, superoxide dismutase, and advanced glycation end-products in the blood were measured. The expression of adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and AMPK target genes were examined in the sciatic nerves of the animals. It was found that metformin was capable of attenuating diabetes-induced mechanical hyperalgesia, heat hyperalgesia and cold allodynia. In addition, metformin was capable of decreasing malondialdehyde and glycation end-products levels in blood, as well as increasing superoxide dismutas activity, indicating the inhibitory effect of metformin against diabetes-induced oxidative stress. Further studies showed that metformin could activate AMPK and increase the AMPK target genes in sciatic nerves in diabetic rats. In conclusion, metformin is able to attenuate diabetes-induced hyperalgesia and allodynia, which might be associated its anti-oxidative effect through AMPK pathway. Metformin might be used as an effective drug, especially with fewer side effects, for abnormal sensation in painful diabetic neuropathy.

  7. Blockade of calcium channels can prevent the onset of secondary hyperalgesia and allodynia induced by intradermal injection of capsaicin in rats.

    PubMed

    Sluka, K A

    1997-06-01

    Intradermal capsaicin injection in humans results in primary hyperalgesia to heat and mechanical stimuli applied near the injection site, as well as secondary mechanical hyperalgesia (increased pain from noxious stimuli) and mechanical allodynia (pain from innocuous stimuli) in an area surrounding the site of primary hyperalgesia. This study in rats tested the hypothesis that the secondary hyperalgesia and allodynia observed following intradermal injection of capsaicin was dependent upon activation of voltage sensitive calcium channels in the spinal cord. Responses to application of von Frey filaments of 10 mN and 90 mN bending forces were tested in all rats before and after injection of capsaicin into the plantar surface of a hindpaw. Animals were pretreated with L-type (nifedipine), N-type (omega-conotoxin GVIA) or P-type (omega-agatoxin IVA) calcium channels blockers through a microdialysis fiber implanted in the spinal dorsal horn prior to the injection of capsaicin. None of the calcium channel blockers had any affect on normal sensory or motor responses. However, all three blockers dose dependently prevented the development of secondary mechanical hyperalgesia and allodynia. The threshold to mechanical stimulation with von Frey filaments was also increased significantly in animals treated with these calcium channel blockers when compared to articial cerebrospinal fluid control animals. These data suggest that calcium channels are important for the development of mechanical hyperalgesia and allodynia that occurs following capsaicin injection. PMID:9211477

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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

  14. 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

  15. 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

  16. Fentanyl-induced hyperalgesia in acute pain management.

    PubMed

    Lyons, Pamela J; Rivosecchi, Ryan M; Nery, Jose P; Kane-Gill, Sandra L

    2015-06-01

    There are safety concerns with the use of fentanyl, including respiratory depression, nausea, constipation, and possibly opioid-induced hyperalgesia (OIH). The purpose of this review is to evaluate the occurrence and significance of opioid-induced hyperalgesia (OIH) after acute fentanyl exposure. A literature search was conducted from October 1995 through January 2015 using MEDLINE, Embase, and Scopus with the terms hyperalgesia, fentanyl, pronociceptive, acute tolerance, and acute. Published articles evaluating the adverse effects of fentanyl during acute pain management (≤96 hours) in humans were included. Opioid-induced hyperalgesia is a phenomenon defined by increasing pain after opioid exposure with the worsening of pain occurring when opioid doses are increased. Hyperalgesia has been described following remifentanil and morphine use, but the question remains about the associated risk with acute fentanyl exposure. Six randomized, controlled trials evaluating the effect of fentanyl on pain in the acute setting have been conducted. Two trials oppose whereas four trials support the occurrence of fentanyl-induced hyperalgesia. The data on OIH after acute fentanyl exposure are limited and conflicting. Hyperalgesia should be considered in patients with uncontrolled pain despite escalating fentanyl doses, since the possibility of fentanyl-induced OIH exists in the acute setting. Well-designed trials are needed to determine the clinical significance of this phenomenon.

  17. 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

  18. 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

  19. 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

  20. Mechanisms of interleukin-10-mediated immune suppression

    PubMed Central

    Akdis, Cezmi A; Blaser, Kurt

    2001-01-01

    Specific immune suppression and induction of anergy are essential processes in the regulation and circumvention of immune defence. Interleukin-10 (IL-10), a suppressor cytokine of T-cell proliferative and cytokine responses, plays a key regulatory role in tolerizing exogenous antigens during specific immunotherapy (SIT) of allergy and natural exposure to antigens. Specific T-cell tolerance is directed against the T-cell epitopes of an antigen and characterized by suppressed proliferative and T helper type 1 (Th1) and type 2 (Th2) cytokine responses. IL-10 elicits tolerance in T cells by selective inhibition of the CD28 co-stimulatory pathway and thereby controls suppression and development of antigen-specific immunity. IL-10 only inhibits T cells stimulated by low numbers of triggered T-cell receptors and which therefore depend on CD28 co-stimulation. T cells receiving a strong signal from the T-cell receptor alone, and thus not requiring CD28 co-stimulation, are not affected by IL-10. IL-10 inhibits CD28 tyrosine phosphorylation, the initial step of the CD28 signalling pathway, and consequently the phosphatidylinositol 3-kinase p85 binding to CD28. Together these results demonstrate that IL-10-induced selective inhibition of the CD28 co-stimulatory pathway acts as a decisive mechanism in determining whether a T cell will contribute to an immune response or become anergic. PMID:11412299

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

    PubMed

    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.

  2. The beta-lactam antibiotic, ceftriaxone, inhibits the development of opioid-induced hyperalgesia in mice.

    PubMed

    Chen, Zhijun; He, Ying; Wang, Zaijie Jim

    2012-02-16

    The glutamate transporter GLT-1 is primarily responsible for glutamate clearance in the spinal cord. beta-Lactam antibiotics have been shown to attenuate neuropathic pain behaviors by promoting GLT-1 expression and function in the CNS. The present study tested the hypothesis that ceftriaxone, a prototype beta-lactam antibiotic, can prevent the development of opioid-induced hyperalgesia (OIH) in mice. Repeated morphine administration produced mechanical allodynia and thermal hyperalgesia, signs of OIH, and reduced spinal GLT-1 expression in mice. Ceftriaxone (200mg/kg/d, i.p., for 7 d) inhibited OIH. Correlating with the behavioral effects, ceftriaxone reversed downregulation of GLT-1 expression that was induced by OIH. These results suggest that ceftriaxone inhibited the development of OIH by up-regulating spinal GLT-1 expression.

  3. 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

  4. 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

  5. Intraneural dexamethasone applied simultaneously to rat sciatic nerve constriction delays the development of hyperalgesia and allodynia.

    PubMed

    Bastos, Leandro F S; Medeiros, Daniel C; Vieira, Rafael P; Watkins, Linda R; Coelho, Márcio M; Moraes, Márcio F D

    2012-02-21

    Although neuroimmune interactions associated with the development of pain sensitization in models of neuropathic pain have been widely studied, there are some aspects that require further investigation. Thus, we aimed to evaluate whether the local intraneural or perineural injections of dexamethasone, an efficacious anti-inflammatory and immunosuppressant drug, delays the development of both thermal hyperalgesia and mechanical allodynia in an experimental model of neuropathic pain in rats. Hargreaves and electronic von Frey tests were applied. The chronic constriction injury (CCI) of right sciatic nerve was performed. Single intraneural dexamethasone administration at the moment of constriction delayed the development of sensitization for thermal hyperalgesia and mechanical allodynia. However, perineural administration of dexamethasone, at the highest dose, did not delay experimental pain development. These results show that inflammation/immune response at the site of nerve lesion is an essential trigger for the pathological changes that lead to both hyperalgesia and allodynia. In conclusion, this approach opens new opportunities to study cellular and molecular neuroimmune interactions associated with the development of pain derived from peripheral neuropathies. PMID:22240103

  6. alpha(1)-Adrenoceptors augment thermal hyperalgesia in mildly burnt skin.

    PubMed

    Drummond, Peter D

    2009-03-01

    The effect of the alpha(1)-adrenoceptor agonist phenylephrine on sensitivity to heat was investigated at three sites of mild burn injury in the cutaneous forearm of 19 healthy participants. Two of the sites were pre-treated with the alpha(1)-antagonist terazosin, to determine whether the effect of phenylephrine was mediated by alpha(1)-adrenoceptors. Terazosin was administered before the burn injury at one site, and after the burn injury at the other site. In another 15 participants, the nociceptive effect of the alpha(2)-adrenoceptor agonist clonidine was investigated with and without prior treatment with the alpha(2)-antagonist rauwolscine. Drugs were introduced into the skin by iontophoresis, and burns were induced by heating the skin to 48 degrees C for 2min. Heat pain thresholds to a temperature ramp (0.5 degrees C/s), and heat pain ratings to a thermal stimulus (45 degrees C, 7s), were determined before and after the administration of each drug. Thermal hyperalgesia provoked by phenylephrine was inhibited by terazosin administered after the burn injury, but not by terazosin administered before the burn injury. However, neither alpha(2)-adrenoceptor stimulation nor blockade affected sensitivity to heat in the mildly burnt skin. These findings suggest that stimulation of cutaneous alpha(1)-adrenoceptors increased the excitability of heat-sensitized nociceptive afferents. As terazosin was more effective when administered in burnt skin, an inflammatory response induced by the burn injury may have facilitated access of adrenergic agents to alpha(1)-adrenoceptors.

  7. 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…

  8. The effect of the sex of a model on nocebo hyperalgesia induced by social observational learning.

    PubMed

    Swider, Karolina; Bąbel, Przemysław

    2013-08-01

    Research shows that placebo analgesia can be induced through social observational learning. Our aim was to replicate and extend this result by studying the effect of the sex of both the model and the subject on the magnitude of placebo analgesia induced by social observational learning. Four experimental (1 through 4) and 2 control (5 and 6) groups were observed: groups 1, 3, and 5 were female; groups 2, 4, and 6 were male. All subjects received pain stimuli of the same intensity preceded by green and red lights. Before receiving pain stimuli, groups 1 and 4 observed a female model and groups 2 and 3 a male model; both models simulated responses to pain stimuli preceded by green lights as less painful than those preceded by red lights. Groups 1 through 4 also rated pain stimuli preceded by green lights as less painful. Further investigation revealed that in fact subjects in experimental groups rated red-associated stimuli as more painful than subjects from control groups who did not observe a model before receiving the same pain stimuli, indicating that nocebo hyperalgesia rather than placebo analgesia was induced. Empathy traits predicted the magnitude of nocebo hyperalgesia. Regardless of the sex of the subject, nocebo hyperalgesia was greater after the male model was observed. The results show that social observational learning is a mechanism that produces placebo effects. They also indicate that the sex of the model plays an important role in this process.

  9. [Mechanism of mediators in human skin. Pharmacoanalysis and therapeutic aspects].

    PubMed

    Stüttgen, G

    1977-06-01

    Under physiological and pathological conditions, the skin is influenced by tissue hormones (biogenic amines, kinines, prostaglandines), neuro-hormones (acetylcholine, catecholamines) and by proteins as complement. The combination of neurological stimulation with a series of self-propagating metabolic changes, shows new aspects of tissue reaction. Histamine triggers a serie of mediators as kinines and prostaglandines. Due to their influence on mediators and their effects on regulatory mechanisms the cyclic nucleotides can serve as model substances for the development of therapeutic processes for dermatological as well as for other disorders. The influence on mediator-systems by topical treatment and proven permeability of such substances is of extreme importance for the future development of local dermatological therapy.

  10. Regionally selective activation of ERK and JNK in morphine paradoxical hyperalgesia: a step toward improving opioid pain therapy.

    PubMed

    Sanna, Maria Domenica; Ghelardini, Carla; Galeotti, Nicoletta

    2014-11-01

    In addition to analgesia, opioid agonists may increase pain sensitivity under different conditions varying dose and administration pattern. While opioid hyperalgesia induced by tolerance and withdrawal is largely studied, little is known on the mechanisms underlying ultra-low dose morphine hyperalgesia. This pronociceptive response appears to play an opposing role in morphine analgesia and might have clinical relevance. Ultra-low dose morphine elicited thermal hyperalgesia through activation of μ opioid receptors. To elucidate the intracellular mechanism of morphine nociceptive behaviour, we investigated the mitogen-activated protein kinase (MAPK), crucial pathways in pain hypersensitivity. The catalytic activity of extracellular signal-regulated kinase (ERK), p38, c-Jun-N-terminal kinase (JNK), upstream modulators and transcription factors was investigated in the mouse periaqueductal grey matter (PAG), thalamus and prefrontal cortex by western blotting. Ultra-low dose morphine intensively increased pERK1 contents in the PAG and cortex and, to a lesser extent, increased cortical ERK2 and JNK phosphorylation. No involvement of p38 was detected. Morphine exposure also increased phosphorylation of cortical c-Jun whereas levels of phosphorylated cAMP response element-binding protein (CREB) remained unmodified. Blockade of protein kinase C (PKC) prevented increases in phosphorylation showing a PKC-dependent mechanism of activation. Pharmacological inhibitors of PKC, ERK, and JNK activity prevented morphine hyperalgesia. No modulation of MAPK and transcription factors' activity was detected in the thalamus. These results support the concept that selective activation of ERK and JNK on descending pathways plays an important role in ultra-low dose morphine hyperalgesia. The modulation of these signalling processes might improve pain management with opiate analgesics.

  11. 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

  12. Opioid-Induced Hyperalgesia: A Diagnostic Dilemma.

    PubMed

    Carullo, Veronica; Fitz-James, Ingrid; Delphin, Ellise

    2015-01-01

    Opioids are utilized frequently for the treatment of moderate to severe acute pain in the perioperative setting, as well as in the treatment of cancer-related pain. When prescribing chronic opioid therapy to patients with chronic pain, it is crucial for the practitioner to be aware not only of the issues of tolerance and withdrawal, but also to have knowledge of the possibility for opioid-induced hyperalgesia (OIH). An understanding of the differences between tolerance and OIH when escalating opioid therapy allows the titration of opioid as well as nonopioid analgesics in order to obtain maximum control of both chronic and acute pain. A case study is described to highlight the importance of judicious utilization of opioids in the treatment of cancer-related pain. In this case, high-dose opioid therapy did not improve chronic pain and contributed to a hyperalgesic state in which a young man experienced severe intractable pain postoperatively after two routine thoracotomies, despite aggressive pharmacologic measures to manage his perioperative pain. Furthermore, it illustrates the potential advantages of opioid rotation to methadone when OIH is suspected.

  13. 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

  14. 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

  15. Chronic psychosocial stress induces visceral hyperalgesia in mice.

    PubMed

    Tramullas, Mónica; Dinan, Timothy G; Cryan, John F

    2012-05-01

    Experimental and clinical evidence has shown that chronic stress plays an important role in the onset and/or exacerbation of symptoms of functional gastrointestinal disorders. Here, we aimed to investigate whether exposure to a chronic and temporally unpredictable psychosocial stressor alters visceral and somatic nociception as well as anxiety-related behaviour. In male C57BL/6J mice, chronic stress was induced by repeated exposure to social defeat (SD, 2 h) and overcrowding (OC, 24 h) during 19 consecutive days. Visceral and somatic nociception was evaluated by colorectal distension and a hot plate, respectively. The social interaction test was used to assess social anxiety. Mice exposed to psychosocial stress developed visceral hyperalgesia and somatic hypoalgesia 24 h following the last stress session. SD/OC mice also exhibited social anxiety-like behaviour. All these changes were also associated with physiological alterations, measured as a decreased faecal pellet output and hypothalamic-pituitary-adrenal (HPA) axis disruption. Taken together, these data confirm that this mouse model of chronic psychosocial stress may be useful for studies on the pathophysiological mechanisms underlying such stress-associated disorders and to further test potential therapies.

  16. 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.

  17. 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

  18. 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

  19. 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.

  20. Activation of cannabinoid CB2 receptors reduces hyperalgesia in an experimental autoimmune encephalomyelitis mouse model of multiple sclerosis.

    PubMed

    Fu, Weisi; Taylor, Bradley K

    2015-05-19

    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. Four weeks after induction of experimental autoimmune encephalomyelitis, we found that intrathecal administration of JWH-133 (10-100μg) 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 (1-3μg). 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.

  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. Mechanisms of Klebsiella pneumoniae resistance to complement-mediated killing.

    PubMed Central

    Merino, S; Camprubí, S; Albertí, S; Benedí, V J; Tomás, J M

    1992-01-01

    The different mechanisms of Klebsiella pneumoniae resistance to complement-mediated killing were investigated by using different strains and isogenic mutants previously characterized for their surface components. We found that strains from serotypes whose K antigen masks the lipopolysaccharide (LPS) molecules (such as serotypes K1, K10, and K16) fail to activate complement, while strains with smooth LPS exposed at the cell surface (with or without K antigen) activate complement but are resistant to complement-mediated killing. The reasons for this resistance are that C3b binds far from the cell membrane and that the lytic final complex C5b-9 (membrane attack complex) is not formed. Isogenic rough mutants (K+ or K-) are serum sensitive because they bind C3b close to the cell membrane and the lytic complex (C5b-9) is formed. Images PMID:1587619

  3. 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

  4. 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

  5. Mechanisms of endonuclease-mediated mRNA decay.

    PubMed

    Schoenberg, Daniel R

    2011-01-01

    Endonuclease cleavage was one of the first identified mechanisms of mRNA decay but until recently it was thought to play a minor role to the better-known processes of deadenylation, decapping, and exonuclease-catalyzed decay. Most of the early examples of endonuclease decay came from studies of a particular mRNA whose turnover changed in response to hormone, cytokine, developmental, or nutritional stimuli. Only a few of these examples of endonuclease-mediated mRNA decay progressed to the point where the enzyme responsible for the initiating event was identified and studied in detail. The discovery of microRNAs and RISC-catalyzed endonuclease cleavage followed by the identification of PIN (pilT N-terminal) domains that impart endonuclease activity to a number of the proteins involved in mRNA decay has led to a resurgence of interest in endonuclease-mediated mRNA decay. PIN domains show no substrate selectivity and their involvement in a number of decay pathways highlights a recurring theme that the context in which an endonuclease function is a primary factor in determining whether any given mRNA will be targeted for decay by this or the default exonuclease-mediated decay processes.

  6. 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

  7. 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

  8. 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

  9. A comparison of chronic aspartame exposure to aspirin on inflammation, hyperalgesia and open field activity following carrageenan-induced monoarthritis.

    PubMed

    LaBuda, C J; Fuchs, P N

    2001-06-15

    The purpose of the present study was to investigate whether chronic aspartame exposure possesses analgesic and anti-inflammatory actions in the carrageenan-induced monoarthritis model similar to those properties of aspirin. Prior research demonstrated that aspartame can reduce second phase formalin pain and increase motor activity in arthritic patients. Fifty-eight male Sprague-Dawly rats were treated with aspartame (25, 50, 100 mg/kg) or saline for six days. An additional group of animals received daily injections of saline and on the sixth treatment day, received a 150-mg/kg dose of aspirin 30-minutes prior to behavioral testing. On Day 6, animals received an intra-articular (i.a.) injection of 2% lambda carrageenan (CARR) or an equal volume of saline and were tested four hours later on threshold to mechanical and thermal stimuli, open field activity, and knee joint diameter. Aspirin-treated arthritic animals exhibited significantly less mechanical hyperalgesia and knee joint inflammation compared with vehicle treated arthritic animals. However, aspirin did not reverse thermal hyperalgesia or increase motor activity to control levels. Aspartame did not reduce inflammation, increase motor activity, or attenuate thermal allodynia, but at 50 mg/kg did attenuate mechanical allodynia compared with vehicle treated arthritic animals. The anti-hyperalgesic effect on mechanical hyperalgesia was not seen at 25 mg/kg or 100 mg/kg aspartame. These results suggest that a certain amount of aspartame may provide relief of arthritic pain to a similar degree as aspirin in some individuals. The specific effect of aspartame and aspirin on mechanical hyperalgesia should be considered when these agents are used for the therapeutic treatment of arthritic conditions.

  10. 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.

  11. A comprehensive review of opioid-induced hyperalgesia.

    PubMed

    Lee, Marion; Silverman, Sanford M; Hansen, Hans; Patel, Vikram B; Manchikanti, Laxmaiah

    2011-01-01

    Opioid-induced hyperalgesia (OIH) is defined as a state of nociceptive sensitization caused by exposure to opioids. The condition is characterized by a paradoxical response whereby a patient receiving opioids for the treatment of pain could actually become more sensitive to certain painful stimuli. The type of pain experienced might be the same as the underlying pain or might be different from the original underlying pain. OIH appears to be a distinct, definable, and characteristic phenomenon that could explain loss of opioid efficacy in some patients. Findings of the clinical prevalence of OIH are not available. However, several observational, cross-sectional, and prospective controlled trials have examined the expression and potential clinical significance of OIH in humans. Most studies have been conducted using several distinct cohorts and methodologies utilizing former opioid addicts on methadone maintenance therapy, perioperative exposure to opioids in patients undergoing surgery, and healthy human volunteers after acute opioid exposure using human experimental pain testing. The precise molecular mechanism of OIH, while not yet understood, varies substantially in the basic science literature, as well as clinical medicine. It is generally thought to result from neuroplastic changes in the peripheral and central nervous system (CNS) that lead to sensitization of pronociceptive pathways. While there are many proposed mechanisms for OIH, 5 mechanisms involving the central glutaminergic system, spinal dynorphins, descending facilitation, genetic mechanisms, and decreased reuptake and enhanced nociceptive response have been described as the important mechanisms. Of these, the central glutaminergic system is considered the most common possibility. Another is the hypothesis that N-methyl-D-aspartate (NMDA) receptors in OIH include activation, inhibition of the glutamate transporter system, facilitation of calcium regulated intracellular protein kinase C, and cross

  12. Intraplantar-injected ceramide in rats induces hyperalgesia through an NF-κB- and p38 kinase-dependent cyclooxygenase 2/prostaglandin E2 pathway

    PubMed Central

    Doyle, Tim; Chen, Zhoumou; Muscoli, Carolina; Obeid, Lina M.; Salvemini, Daniela

    2011-01-01

    Inflammatory pain represents an important unmet clinical need with important socioeconomic implications. Ceramide, a potent proinflammatory sphingolipid, has been shown to elicit mechanical hyperalgesia, but the mechanisms remain largely unknown. We now demonstrate that, in addition to mechanical hyperalgesia, intraplantar injection of ceramide (10 μg) led to the development of thermal hyperalgesia that was dependent on induction of the inducible cyclooxygenase (COX-2) and subsequent increase of prostaglandin E2 (PGE2). The development of mechanical and thermal hyperalgesia and increased production of PGE2 was blocked by NS-398 (15–150 ng), a selective COX-2 inhibitor. The importance of the COX-2 to PGE2 pathway in ceramide signaling was underscored by the findings that intraplantar injection of a monoclonal PGE2 antibody (4 μg) blocked the development of hyperalgesia. Our results further revealed that COX-2 induction is regulated by NF-κB and p38 kinase activation, since intraplantar injection of SC-514 (0.1–1 μg) or SB 203580 (1–10 μg), well-characterized inhibitors of NF-κB and p38 kinase activation, respectively, blocked COX-2 induction and increased formation of PGE2 and thermal hyperalgesia in a dose-dependent manner. Moreover, activation of NF-κB was dependent on upstream activation of p38 MAPK, since SB 203580 (10 μg) blocked p65 phosphorylation, whereas p38 kinase phosphorylation was unaffected by NF-κB inhibition by SC-514 (1 μg). Our findings not only provide mechanistic insight into the signaling pathways engaged by ceramide in the development of hyperalgesia, but also provide a potential pharmacological basis for developing inhibitors targeting the ceramide metabolic-to-COX-2 pathway as novel analgesics.—Doyle, T., Chen, Z., Muscoli, C., Obeid, L. M., Salvemini, D. Intraplantar-injected ceramide in rats induces hyperalgesia through an NF-κB- and p38 kinase-dependent cyclooxygenase 2/prostaglandin E2 pathway. PMID:21551240

  13. Dezocine Prevents Postoperative Hyperalgesia in Patients Undergoing Open Abdominal Surgery

    PubMed Central

    Yu, Fang; Zhou, Jie; Xia, Suyun; Xu, Huan; Wang, Xiangrui

    2015-01-01

    Objective. Postoperative hyperalgesia is very frequent and hard to treat. Dezocine is widely used and has a modulatory effect for thermal hyperalgesia in animal models. So, this study was designed to investigate the potential role of dezocine in decreasing postoperative hyperalgesia for patients undergoing open abdominal surgery. Methods. This is a randomized, double-blinded, and placebo-controlled trial. 50 patients for elective open gastrectomy were randomly allocated to either a true treatment group (0.15 mg/kg intravenous dezocine at the end of surgery) or a sham treatment group (equivalent volume of saline) in a 1 : 1 ratio. Patients were followed up for 48 hours postoperatively and pain threshold to Von Frey filaments, pain scores, PCIA consumption, rescue analgesics use, sedation score, and occurrence of postoperative nausea and vomiting were recorded. Results. Patients in the true treatment group experienced statistically significantly higher pain threshold on forearm and smaller extent of peri-incisional hyperalgesia than the sham treatment group. Rescue analgesic use, cumulative PCIA consumption, and pain scores were statistically significantly decreased in the true treatment group compared to the sham treatment group. Conclusions. Dezocine offers a significant antihyperalgesic and analgesic effect in patients undergoing elective open gastrectomy for up to 48 hours postoperatively. PMID:26170890

  14. 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

  15. Transplant-mediated enhancement of spinal cord GABAergic inhibition reverses paclitaxel-induced mechanical and heat hypersensitivity.

    PubMed

    Bráz, João M; Wang, Xidao; Guan, Zhonghui; Rubenstein, John L; Basbaum, Allan I

    2015-06-01

    Decreased spinal cord GABAergic inhibition is a major contributor to the persistent neuropathic pain that can follow peripheral nerve injury. Recently, we reported that restoring spinal cord GABAergic signaling by intraspinal transplantation of cortical precursors of GABAergic interneurons from the embryonic medial ganglionic eminence (MGE) can reverse the mechanical hypersensitivity (allodynia) that characterizes a neuropathic pain model in the mouse. We show that MGE cell transplants are also effective against both the mechanical allodynia and the heat hyperalgesia produced in a paclitaxel-induced chemotherapy model of neuropathic pain. To test the necessity of GABA release by the transplants, we also studied the utility of transplanting MGE cells from mice with a deletion of VGAT, the vesicular GABA transporter. Transplants from these mice, in which GABA is synthesized but cannot be stored or released, had no effect on mechanical hypersensitivity or heat hyperalgesia in the paclitaxel model. Taken together, these results demonstrate the therapeutic potential of GABAergic precursor cell transplantation in diverse neuropathic pain models and support our contention that restoration of inhibitory controls through release of GABA from the transplants is their mode of action. PMID:25760475

  16. 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

  17. 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

  18. Mechanisms and Representations of Language-Mediated Visual Attention

    PubMed Central

    Huettig, Falk; Mishra, Ramesh Kumar; Olivers, Christian N. L.

    2011-01-01

    The experimental investigation of language-mediated visual attention is a promising way to study the interaction of the cognitive systems involved in language, vision, attention, and memory. Here we highlight four challenges for a mechanistic account of this oculomotor behavior: the levels of representation at which language-derived and vision-derived representations are integrated; attentional mechanisms; types of memory; and the degree of individual and group differences. Central points in our discussion are (a) the possibility that local microcircuitries involving feedforward and feedback loops instantiate a common representational substrate of linguistic and non-linguistic information and attention; and (b) that an explicit working memory may be central to explaining interactions between language and visual attention. We conclude that a synthesis of further experimental evidence from a variety of fields of inquiry and the testing of distinct, non-student, participant populations will prove to be critical. PMID:22291672

  19. Surface mechanics mediate pattern formation in the developing retina.

    PubMed

    Hayashi, Takashi; Carthew, Richard W

    2004-10-01

    Pattern formation of biological structures involves organizing different types of cells into a spatial configuration. In this study, we investigate the physical basis of biological patterning of the Drosophila retina in vivo. We demonstrate that E- and N-cadherins mediate apical adhesion between retina epithelial cells. Differential expression of N-cadherin within a sub-group of retinal cells (cone cells) causes them to form an overall shape that minimizes their surface contact with surrounding cells. The cells within this group, in both normal and experimentally manipulated conditions, pack together in the same way as soap bubbles do. The shaping of the cone cell group and packing of its components precisely imitate the physical tendency for surfaces to be minimized. Thus, simple patterned expression of N-cadherin results in a complex spatial pattern of cells owing to cellular surface mechanics. PMID:15470418

  20. Mechanisms for macrophage-mediated HIV-1 induction.

    PubMed

    Devadas, Krishnakumar; Hardegen, Neil J; Wahl, Larry M; Hewlett, Indira K; Clouse, Kathleen A; Yamada, Kenneth M; Dhawan, Subhash

    2004-12-01

    Viral latency is a long-term pathogenic condition in patients infected with HIV-1. Low but sustained virus replication in chronically infected cells can be activated by stimulation with proinflammatory cytokines such as TNF-alpha, IL-1 beta, or other host factors. However, the precise mechanism by which cellular activation induces latently infected cells to produce virions has remained unclear. In the present report, we present evidence that activation of HIV-1 replication in latently infected U1 or ACH2 cells by human macrophages is mediated by a rapid nuclear localization of NF-kappaB p50/p65 dimer with concomitant increased expression of proinflammatory cytokines. Multiplexed RT-PCR amplification of mRNA isolated from cocultures of macrophages and U1 and ACH2 cells showed significant induction of IL-1beta, IL-6, IL-8, TNF-alpha, and TGF-beta expression within 3 h of coincubation. Fixation of macrophages, U-1, or ACH2 cells with paraformaldehyde before coculture completely abrogated the induction of NF-kappaB subunits and HIV-1 replication, suggesting that cooperative interaction between the two cell types is an essential process for cellular activation. Pretreatment of macrophage-U1 or macrophage-ACH2 cocultures with neutralizing anti-TNF-alpha Ab down-regulated the replication of HIV-1. In addition, pretreatment of macrophage-U1 or macrophage-ACH2 cocultures with the NF-kappaB inhibitor (E)3-[(4-methylphenyl)sulfonyl]-2-propenenitrile (BAY 11-7082) prevented the induction of cytokine expression, indicating a pivotal role of NF-kappaB-mediated signaling in the reactivation of HIV-1 in latently infected cells by macrophages. These results provide a mechanism by which macrophages induce HIV-1 replication in latently infected cells.

  1. 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

  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. Continuing to illuminate the mechanisms underlying UV-mediated melanomagenesis

    PubMed Central

    Dellinger, Ryan W.; Liu-Smith, Feng; Meyskens, Frank L.

    2014-01-01

    The incidence of melanoma is one of the fastest growing of all tumor types in the United States and the number of cases worldwide has doubled in the past 30 years. Melanoma, which arises from melanocytes, is an extremely aggressive tumor that invades the vascular and lymphatic systems to establish tumors elsewhere in the body. Melanoma is a particularly resilient cancer and systemic therapy approaches have achieved minimal success against metastatic melanoma resulting in only a few FDA-approved treatments with limited benefit. Leading treatments offer minimal efficacy with response rates generally under 15% in the long term with no clear effect on melanoma-related mortality. Even the recent success of the specific BRAF mutant inhibitor vemurafenib has been tempered somewhat since acquired resistance is rapidly observed. Thus, understanding the mechanism(s) of melanoma carcinogenesis is paramount to combating this deadly disease. Not only for the treatment of melanoma but, ultimately, for prevention. In this report, we will summarize our work to date regarding the characterization of ultraviolet radiation (UVR)-mediated melanomagenesis and highlight several promising avenues of ongoing research. PMID:25022944

  4. Minireview: mechanisms of growth hormone-mediated gene regulation.

    PubMed

    Chia, Dennis J

    2014-07-01

    GH exerts a diverse array of physiological actions that include prominent roles in growth and metabolism, with a major contribution via stimulating IGF-1 synthesis. GH achieves its effects by influencing gene expression profiles, and Igf1 is a key transcriptional target of GH signaling in liver and other tissues. This review examines the mechanisms of GH-mediated gene regulation that begin with signal transduction pathways activated downstream of the GH receptor and continue with chromatin events at target genes and additionally encompasses the topics of negative regulation and cross talk with other cellular inputs. The transcription factor, signal transducer and activator of transcription 5b, is regarded as the major signaling pathway by which GH achieves its physiological effects, including in stimulating Igf1 gene transcription in liver. Recent studies exploring the mechanisms of how activated signal transducer and activator of transcription 5b accomplishes this are highlighted, which begin to characterize epigenetic features at regulatory domains of the Igf1 locus. Further research in this field offers promise to better understand the GH-IGF-1 axis in normal physiology and disease and to identify strategies to manipulate the axis to improve human health.

  5. 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

  6. Mediators and mechanisms of relaxation in rabbit urethral smooth muscle

    PubMed Central

    Waldeck, Kristian; Ny, Lars; Persson, Katarina; Andersson, Karl-Erik

    1998-01-01

    Electrophysiological and mechanical experiments were performed to investigate whether the nitric oxide (NO)-mediated relaxation of rabbit urethral smooth muscle is associated with a hyperpolarization of the membrane potential. In addition, a possible role for vasoactive intestinal peptide (VIP) and carbon monoxide (CO) as relaxant agents in rabbit urethra was investigated. Immunohistochemical experiments were performed to characterize the NO-synthase (NOS) and VIP innervation. Possible target cells for NO were studied by using antisera against cyclic GMP. The cyclic GMP-immunoreactivity was investigated on tissues pretreated with 1 mM IBMX, 0.1 mM zaprinast and 1 mM sodium nitroprusside. Intracellular recordings of the membrane potential in the circular smooth muscle layer revealed two types of spontaneous depolarizations, slow waves with a duration of 3–4 s and an amplitude of 30–40 mV, and faster (0.5–1 s), more irregular depolarizations with an amplitude of 5–15 mV. The resting membrane potential was 39±1 mV (n=12). Application of NO (30 μM), CO (30 μM) or VIP (1 μM) did not change the resting membrane potential. Both NO (1–100 μM) and VIP (1 nM–1 μM) produced concentration-dependent relaxations amounting to 87±4% and 97±2% (n=6), respectively. The relaxant effect of CO (1–30 μM) amounted to 27±4% (n=5) at the highest concentration used. Immunohistochemical experiments revealed a rich supply of NOS-immunoreactive nerve fibres in the smooth muscle layers. Numerous spinous cyclic GMP-immunoreactive cells were found interspersed between the smooth muscle bundles, mainly localized in the outer layer. These cells had long processes forming a network surrounding the smooth muscle bundles. VIP-immunoreactivity was sparse in comparison to NOS-immunoreactive nerves. The rich supply of NOS-immunoreactive nerve fibres supports the view that NO is an important NANC-mediator in the rabbit urethra. In contrast to several

  7. Suspected opioid-induced hyperalgesia in an infant.

    PubMed

    Hallett, B R; Chalkiadis, G A

    2012-01-01

    One explanation for diminished opioid analgesic efficacy is opioid-induced hyperalgesia (OIH). We report a case of OIH in an infant with gastroschisis, requiring multiple surgical interventions and prolonged sedation for ventilation. This is the first report of OIH in an infant. On day 41 of life after nine separate surgical interventions, the patient's pain scores increased and remained elevated, despite increasing opioid administration. The patient also developed hyperalgesia, allodynia, and photophobia and became extremely irritable upon handling. Other possible causes were excluded, including interruption to opioid delivery, sepsis, acid-base and electrolyte disturbance, and ongoing surgical pathology. An opioid rotation to hydromorphone was initiated and ketamine was commenced. Sedation for ventilation was achieved with dexmedetomidine and midazolam infusions. Over a period of 24 h after opioid de-escalation, pain scores reduced rapidly and the patient became significantly less irritable with handling. All infusions were gradually weaned and eventually ceased.

  8. When medications make pain worse: opioid-induced hyperalgesia.

    PubMed

    Martin, Caren McHenry

    2011-08-01

    Opioid medications are commonly used to treat moderate-to-severe pain. While these medications are generally an effective means of pain control, they can, in rare cases, actually exacerbate the pain. This paradoxical reaction is called opioid-induced hyperalgesia (OIH). Patients experiencing OIH may benefit from decreasing or discontinuing the opioid, switching to an alternative opioid, and/or using a nonopioid medication for pain.

  9. 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

  10. 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

  11. Adipokines and the cardiovascular system: mechanisms mediating health and disease.

    PubMed

    Northcott, Josette M; Yeganeh, Azadeh; Taylor, Carla G; Zahradka, Peter; Wigle, Jeffrey T

    2012-08-01

    This review focuses on the role of adipokines in the maintenance of a healthy cardiovascular system, and the mechanisms by which these factors mediate the development of cardiovascular disease in obesity. Adipocytes are the major cell type comprising the adipose tissue. These cells secrete numerous factors, termed adipokines, into the blood, including adiponectin, leptin, resistin, chemerin, omentin, vaspin, and visfatin. Adipose tissue is a highly vascularised endocrine organ, and different adipose depots have distinct adipokine secretion profiles, which are altered with obesity. The ability of many adipokines to stimulate angiogenesis is crucial for adipose tissue expansion; however, excessive blood vessel growth is deleterious. As well, some adipokines induce inflammation, which promotes cardiovascular disease progression. We discuss how these 7 aforementioned adipokines act upon the various cardiovascular cell types (endothelial progenitor cells, endothelial cells, vascular smooth muscle cells, pericytes, cardiomyocytes, and cardiac fibroblasts), the direct effects of these actions, and their overall impact on the cardiovascular system. These were chosen, as these adipokines are secreted predominantly from adipocytes and have known effects on cardiovascular cells.

  12. Conceptual Conditioning: Mechanisms Mediating Conditioning Effects on Pain.

    PubMed

    Jepma, Marieke; Wager, Tor D

    2015-11-01

    Classical conditioning can profoundly modify subsequent pain responses, but the mechanisms that drive this effect are unresolved. In pain-conditioning studies, cues are typically conditioned to primary aversive reinforcers; hence, subsequent pain modulation could reflect learned precognitive associations (i.e., those involving neural plasticity independent of expectations and other forms of conceptual thought) or conceptual expectancies. We isolated conceptual contributions using a thermal pain-conditioning procedure in which different conditioned stimulus (CS) cues were repeatedly paired with symbolic representations of high and low noxious heat. In a subsequent test phase, identical noxious stimuli evoked larger skin conductance responses (SCRs) and pain ratings when preceded by CS cues associated with high temperature than by those associated with low temperature. These effects were mediated by participants' self-reported expectancies. CS cues associated with high temperature also evoked larger anticipatory SCRs than did CS cues associated with low temperature, but larger anticipatory SCRs predicted smaller subsequent heat-evoked SCRs. These results provide novel evidence that conditioned modulation of pain physiology can be acquired through purely conceptual processes, and that self-reported expectancies and physiological threat responses have opposing effects on pain.

  13. Hydrogen-rich saline prevents remifentanil-induced hyperalgesia and inhibits MnSOD nitration via regulation of NR2B-containing NMDA receptor in rats.

    PubMed

    Zhang, L; Shu, R; Wang, H; Yu, Y; Wang, C; Yang, M; Wang, M; Wang, G

    2014-11-01

    Remifentanil administration may subsequently cause paradoxical hyperalgesia in animals and humans, but mechanisms remain unclear. Manganese superoxide dismutase (MnSOD) nitration and inactivation caused by generation of reactive oxygen species and activation of N-methyl-D-aspartate (NMDA) receptors are involved in the induction and maintenance of central neuropathic pain. Hydrogen which selectively removes superoxide has gained much attention in recent years. In this study, we investigated antinociceptive effects of hydrogen-rich saline (HRS) on remifentanil-induced postsurgical hyperalgesia in a rat model of incisional pain. HRS was injected intraperitoneally 10 min before remifentanil infusion (1 μg kg(-1) min(-1) for 60 min). A selective NR2B antagonist Ro25-6981 was used to investigate whether antihypernociception of HRS is associated with NMDA receptor (NMDAR). Nociception was evaluated by the paw withdrawal mechanical threshold and thermal latency respectively. Then we assessed MnSOD, NR2A and NR2B in spinal cord dorsal horn via Western blot and immunohistochemistry after nociceptive tests. Here, we found that the analgesic effect of remifentanil was followed by long-term hyperalgesia lasting at least postoperative 7 days, which was accompanied with increase in NR2B expression and trafficking from cytoplasm to surface and MnSOD nitration in dorsal horn. Pretreatment with HRS (10 ml/kg) significantly attenuated mechanical and thermal hyperalgesia, blocked NR2B trafficking and MnSOD nitration in dorsal horn after remifentanil infusion. Ro25-6981 not 5 μg but 10 and 50 μg dosage-dependently attenuated hyperalgesia, and inhibited MnSOD nitration. Hyperalgesia and MnSOD nitration were attenuated after the combination of HRS (2.5 ml/kg) and Ro25-6981 (5 μg). In conclusion, HRS (10 ml/kg) might reverse remifentanil-induced hyperalgesia, through regulating NR2B-containing NMDAR trafficking to control MnSOD nitration and enhance MnSOD activity.

  14. Opioid-induced hyperalgesia and rapid opioid detoxification after tacrolimus administration.

    PubMed

    Siniscalchi, Antonio; Piraccini, Emanuele; Miklosova, Zuzana; Taddei, Stefania; Faenza, Stefano; Martinelli, Gerardo

    2008-02-01

    Opioids can induce central sensitization and hyperalgesia, referred to as "opioid-induced hyperalgesia." Our report describes a patient who underwent intestinal transplant followed by immunosuppressant-related neuropathic pain. Her pain was treated with limited success over the course of 3 yr with different therapies, including i.v. morphine. She developed opioid-induced hyperalgesia, which was successfully treated with rapid detoxification under general anesthesia. Detoxification improved her quality of life, including the ability to resume physiotherapy. Six months after treatment, she remained opioid free. Our experience suggests that rapid detoxification under general anesthesia may be an effective treatment for opioid-induced hyperalgesia and merits comparison to traditional detoxification methods.

  15. Cellular mechanisms mediating rat renal microvascular constriction by angiotensin II.

    PubMed Central

    Takenaka, T; Suzuki, H; Fujiwara, K; Kanno, Y; Ohno, Y; Hayashi, K; Nagahama, T; Saruta, T

    1997-01-01

    To assess cellular mechanisms mediating afferent (AA) and efferent arteriolar (EA) constriction by angiotensin II (AngII), experiments were performed using isolated perfused hydronephrotic kidneys. In the first series of studies, AngII (0.3 nM) constricted AAs and EAs by 29+/-3 (n = 8, P < 0.01) and 27+/-3% (n = 8, P < 0.01), respectively. Subsequent addition of nifedipine restored AA but not EA diameter. Manganese (8 mM) reversed EA constriction by 65+/-9% (P < 0.01). In the second group, the addition of N-ethylmaleimide (10 microM), a Gi/Go protein antagonist, abolished AngII- induced EA (n = 6) but not AA constriction (n = 6). In the third series of experiments, treatment with 2-nitro-4-carboxyphenyl-N, N-diphenyl-carbamate (200 microM), a phospholipase C inhibitor, blocked both AA and EA constriction by AngII (n = 6 for each). In the fourth group, thapsigargin (1 microM) prevented AngII-induced AA constriction (n = 8) and attenuated EA constriction (8+/-2% decrease in EA diameter at 0.3 nM AngII, n = 8, P < 0.05). Subsequent addition of manganese (8 mM) reversed EA constriction. Our data provide evidence that in AAs, AngII stimulates phospholipase C with subsequent calcium mobilization that is required to activate voltage-dependent calcium channels. Our results suggest that AngII constricts EAs by activating phospholipase C via the Gi protein family, thereby eliciting both calcium mobilization and calcium entry. PMID:9329977

  16. Critical role for Epac1 in inflammatory pain controlled by GRK2-mediated phosphorylation of Epac1

    PubMed Central

    Singhmar, Pooja; Huo, XiaoJiao; Eijkelkamp, Niels; Berciano, Susana Rojo; Baameur, Faiza; Mei, Fang C.; Zhu, Yingmin; Cheng, Xiaodong; Hawke, David; Mayor, Federico; Murga, Cristina; Heijnen, Cobi J.; Kavelaars, Annemieke

    2016-01-01

    cAMP signaling plays a key role in regulating pain sensitivity. Here, we uncover a previously unidentified molecular mechanism in which direct phosphorylation of the exchange protein directly activated by cAMP 1 (EPAC1) by G protein kinase 2 (GRK2) suppresses Epac1-to-Rap1 signaling, thereby inhibiting persistent inflammatory pain. Epac1−/− mice are protected against inflammatory hyperalgesia in the complete Freund’s adjuvant (CFA) model. Moreover, the Epac-specific inhibitor ESI-09 inhibits established CFA-induced mechanical hyperalgesia without affecting normal mechanical sensitivity. At the mechanistic level, CFA increased activity of the Epac target Rap1 in dorsal root ganglia of WT, but not of Epac1−/−, mice. Using sensory neuron-specific overexpression of GRK2 or its kinase-dead mutant in vivo, we demonstrate that GRK2 inhibits CFA-induced hyperalgesia in a kinase activity-dependent manner. In vitro, GRK2 inhibits Epac1-to-Rap1 signaling by phosphorylation of Epac1 at Ser-108 in the Disheveled/Egl-10/pleckstrin domain. This phosphorylation event inhibits agonist-induced translocation of Epac1 to the plasma membrane, thereby reducing Rap1 activation. Finally, we show that GRK2 inhibits Epac1-mediated sensitization of the mechanosensor Piezo2 and that Piezo2 contributes to inflammatory mechanical hyperalgesia. Collectively, these findings identify a key role of Epac1 in chronic inflammatory pain and a molecular mechanism for controlling Epac1 activity and chronic pain through phosphorylation of Epac1 at Ser-108. Importantly, using the Epac inhibitor ESI-09, we validate Epac1 as a potential therapeutic target for chronic pain. PMID:26929333

  17. Effects of COX inhibition on experimental pain and hyperalgesia during and after remifentanil infusion in humans.

    PubMed

    Lenz, Harald; Raeder, Johan; Draegni, Tomas; Heyerdahl, Fridtjof; Schmelz, Martin; Stubhaug, Audun

    2011-06-01

    Opioids may enhance pain sensitivity resulting in opioid-induced hyperalgesia (OIH). Activation of spinal cyclooxygenase may play a role in the development of OIH. The aim of this study was to demonstrate remifentanil-induced postinfusion hyperalgesia in an electrical pain and a cold pain model, and to investigate whether COX-2 (parecoxib) or COX-1 (ketorolac) inhibition could prevent hyperalgesia after remifentanil infusion. Sixteen healthy males were enrolled in this randomized, double-blind, placebo-controlled crossover study. Each subject went through 4 sessions: control, remifentanil, parecoxib+remifentanil, and ketorolac+remifentanil. Transcutaneous electrical stimulation induced acute pain and areas of pinprick hyperalgesia. The areas of pinprick hyperalgesia were assessed before, during, and after a 30-minute infusion of either remifentanil or saline. The cold-pressor test (CPT) was performed before, at the end of, and 1 hour after the infusions. The subjects received a bolus of either saline, 40 mg parecoxib, or 30 mg ketorolac intravenously after the first CPT. The areas of pinprick hyperalgesia and CPT pain after the end of remifentanil infusion increased significantly compared to control (P < 0.001 and P = 0.005, respectively). Pretreatment with parecoxib or ketorolac reduced the postinfusion area of pinprick hyperalgesia (P < 0.001 and P = 0.001, respectively), compared to the remifentanil group. Parecoxib reduced the area significantly more than ketorolac (P = 0.009). In the CPT, pretreatment with parecoxib or ketorolac did not prevent postinfusion hyperalgesia. These results demonstrated OIH in both models, and may suggest that COX-2 inhibition is more important than COX-1 inhibition in reducing hyperalgesia. Remifentanil-induced hyperalgesia was demonstrated for both electrically induced pain and cold-pressor pain. Both parecoxib and ketorolac prevented hyperalgesia in the electrical model, parecoxib to a larger extent.

  18. 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.

  19. 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.

  20. Deficits in visceral pain and referred hyperalgesia in Nav1.8 (SNS/PN3)-null mice.

    PubMed

    Laird, Jennifer M A; Souslova, Veronika; Wood, John N; Cervero, Fernando

    2002-10-01

    The tetrodotoxin-resistant sodium channel alpha subunit Nav1.8 is expressed exclusively in primary sensory neurons and is proposed to play an important role in sensitization of nociceptors. Here we compared visceral pain and referred hyperalgesia in Nav1.8-null mice and their wild-type littermates in five tests that differ in the degree to which behavior depends on spontaneous, ongoing firing in sensitized nociceptors. Nav1.8-null mice showed normal nociceptive behavior provoked by acute noxious stimulation of abdominal viscera (intracolonic saline or intraperitoneal acetylcholine). However, Nav1.8-null mutants showed weak pain and no referred hyperalgesia to intracolonic capsaicin, a model in which behavior is sustained by ongoing activity in nociceptors sensitized by the initial application. Nav1.8-null mice also showed blunted pain and hyperalgesia to intracolonic mustard oil, which sensitizes nociceptors but also provokes tissue damage. To distinguish between a possible role for Nav1.8 in ongoing activity per se and ongoing activity after sensitization in the absence of additional stimuli, we tried a visceral model of tonic noxious chemical stimulation, cyclophosphamide cystitis. Cyclophosphamide produces cystitis by gradual accumulation of toxic metabolites in the bladder. In this model, Nav1.8-null mice showed normal responses. There were no differences between null mutants and their normal littermates in tissue damage and inflammation evoked by any of the stimuli tested, suggesting that the behavioral differences are not secondary to impairment of inflammatory responses. We conclude that there is an essential role for Nav1.8 in mediating spontaneous activity in sensitized nociceptors.

  1. GABAergic Transmission in Rat Pontine Reticular Formation Regulates the Induction Phase of Anesthesia and Modulates Hyperalgesia Caused by Sleep Deprivation

    PubMed Central

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

    2014-01-01

    The oral part of the pontine reticular formation (PnO) contributes to the regulation of sleep, anesthesia, and pain. The role of PnO 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: (1) pharmacologically manipulating GABA levels in rat PnO alters LoRR, RoRR, and nociception; (2) propofol decreases GABA levels in the PnO; and (3) inhibiting GABA synthesis in the PnO blocks hyperalgesia caused by sleep deprivation. Administering a GABA synthesis inhibitor (3-MPA) or a GABA uptake inhibitor (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

  2. 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

  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. Involvement of peripheral ionotropic glutamate receptors in orofacial thermal hyperalgesia in rats

    PubMed Central

    2011-01-01

    Background The purpose of the present study was to elucidate the mechanisms that may underlie the sensitization of trigeminal spinal subnucleus caudalis (Vc) and upper cervical spinal cord (C1-C2) neurons to heat or cold stimulation of the orofacial region following glutamate (Glu) injection. Results Glu application to the tongue or whisker pad skin caused an enhancement of head-withdrawal reflex and extracellular signal-regulated kinase (ERK) phosphorylation in Vc-C2 neurons. Head-withdrawal reflex and ERK phosphorylation were also enhanced following cold stimulation of the tongue but not whisker pad skin in Glu-injected rats, and the head-withdrawal reflex and ERK phosphorylation were enhanced following heat stimulation of the tongue or whisker pad skin. The enhanced head-withdrawal reflex and ERK phosphorylation after heat stimulation of the tongue or whisker pad skin, and those following cold stimulation of the tongue but not whisker pad skin were suppressed following ionotropic glutamate receptor antagonists administration into the tongue or whisker pad skin. Furthermore, intrathecal administration of MEK1/2 inhibitor PD98059 caused significant suppression of enhanced head-withdrawal reflex in Glu-injected rats, heat head-withdrawal reflex in the rats with Glu injection into the tongue or whisker pad skin and cold head-withdrawal reflex in the rats with Glu injection into the tongue. Conclusions The present findings suggest that peripheral Glu receptor mechanisms may contribute to cold hyperalgesia in the tongue but not in the facial skin, and also contribute to heat hyperalgesia in the tongue and facial skin, and that the mitogen-activated protein kinase cascade in Vc-C2 neurons may be involved in these Glu-evoked hyperalgesic effects. PMID:21952000

  5. 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

  6. Amitriptyline reverses hyperalgesia and improves associated mood-like disorders in a model of experimental monoarthritis.

    PubMed

    Amorim, D; David-Pereira, A; Pertovaara, A; Almeida, A; Pinto-Ribeiro, F

    2014-05-15

    Affective disorders are common comorbidities of chronic inflammatory pain that are often overlooked in primary care. As the impact of inflammatory pain upon mood-like disorders in animal models is not well known, our objective was to assess whether prolonged experimental monoarthritis (ARTH) induced the development of anxiety and depressive-like behaviours in rodents and if amitriptyline, an antidepressant commonly used in the treatment of chronic pain, could reverse both nociceptive and mood-like impairments. Experimental ARTH was induced through an injection of kaolin/carrageenan into the right knee joint with control (SHAM) animals injected with saline. Four weeks after induction, ARTH animals displayed mechanical hyperalgesia and a depressive-like phenotype as they showed a significant increase in immobility and a decrease in the latency to immobility in the forced-swimming test at the expense of the time spent climbing/swimming. ARTH animals also displayed a decreased sucrose preference, an index of anhedonia and anxiety-like behaviour as time spent exploring the open arms of the elevated-plus-maze was decreased when compared to controls. The anxiety-like phenotype was also supported by an increase in the number of fecal boli left in the open field. In ARTH animals, the administration of amitriptyline decreased mechanical hyperalgesia and increased sucrose preference and the time spent climbing, although it had a deleterious effect in the performance of control animals. Our data show that this model of ARTH can be useful for the study of chronic pain-mood disorders comorbidities and that amitriptyline is able to partly reverse the associated nociceptive and emotional impairments.

  7. Thermal hyperalgesia after sciatic nerve block in rat is transient and clinically insignificant.

    PubMed

    Janda, Allison; Lydic, Ralph; Welch, Kathleen B; Brummett, Chad M

    2013-01-01

    Ropivacaine has been associated with transient heat hyperalgesia in sciatic nerve blocks in rat. The goal of the present study was to evaluate the hypothesized presence of transient heat hyperalgesia after perineural injection of ropivacaine with a secondary subanalysis of 2 published studies. Paw withdrawal latency was used to assess the duration of sensory blockade and presence of heat hyperalgesia at 210, 240, 270, and 300 minutes and 24 hours after injection. The analysis revealed hyperalgesia at a single time point (240 minutes after injection; mean difference, -0.60 seconds; P = 0.012) that resolved within 30 minutes, and there was no other significant hyperalgesia at other time points. Although statistically significant, the single time point measurement represented only an 11% change from baseline and was no longer present 30 minutes later. These data support the need for a reevaluation of the interpretation that pain can be worsened by perineural ropivacaine injection.

  8. 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

  9. 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.

  10. 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…

  11. 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

  12. 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

  13. Transcutaneous electric acupoint stimulation alleviates remifentanil-induced hyperalgesia in patients undergoing thyroidectomy: a randomized controlled trial

    PubMed Central

    Chen, Yanqing; Yao, Yusheng; Wu, Yihuan; Dai, Dongsheng; Zhao, Qiuyan; Qiu, Liangcheng

    2015-01-01

    Background: In this prospective, randomized, double-blind study, we verified the hypothesis that TEAS can alleviate remifentanil-induced hyperalgesia in patients undergoing thyroidectomy. Methods: 60 American Society of Anesthesiologists physical status (ASA) I-IIpatients, aged 18-60 year, scheduled for thyroidectomy were randomly allocated to TEAS or sham groups. TEAS consisted of 30 min of stimulation (6-9 mA, 2/10 Hz) on the Hegu (LI4) and Neiguan (PC6) before anesthesia. Anesthesia was maintained with sevoflurane adjusted to bispectral index (40-60) and target remifentanil 5.0 ng/ml. Mechanical pain thresholds were assessed using electronic von Frey. The primary outcome was mechanical pain thresholds. Secondary outcomes included postoperative pain scores, the time to first rescue analgesic, cumulative number of rescue analgesia, and side effects, including postoperative nausea and vomiting (PONV), dizziness and shivering in 24 h postoperatively. Results: Baseline mechanical pain thresholds were similar between the groups. The analysis revealed the decrease in mechanical threshold was greater in the sham group than the TEAS group (P < 0.001). Postoperative pain scores and cumulative number of rescue analgesia were lower in the TEAS group (P < 0.05). In addition, TEAS group patients reduced the incidence of PONV and shivering. Conclusion: Preoperative TEAS can attenuate remifentanil-induced hyperalgesia in patients undergoing thyroidectomy. PMID:26131165

  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. 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

  16. Resilience: Mediated by not one but many appraisal mechanisms.

    PubMed

    Juslin, Patrik N

    2015-01-01

    Kalisch et al. discuss the causal process underlying stress in terms of a multidimensional goal-appraisal process, but there are several mechanisms at various levels of the brain that use different types of information to guide behavior. Depending on the mechanism, the characteristics of the process are different. Hence, both research and prevention must deal with appraisal in mechanism-specific ways. PMID:26786390

  17. 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.

  18. The lateral prefrontal cortex mediates the hyperalgesic effects of negative cognitions in chronic pain patients

    PubMed Central

    Loggia, Marco L.; Berna, Chantal; Kim, Jieun; Cahalan, Christine M.; Martel, Marc-Olivier; Gollub, Randy L.; Wasan, Ajay D.; Napadow, Vitaly; Edwards, Robert R.

    2015-01-01

    While high levels of negative affect and cognitions have been associated in chronic pain conditions with greater pain sensitivity, the neural mechanisms mediating the hyperalgesic effect of psychological factors in patients with pain disorders are largely unknown. In this cross-sectional study, we hypothesized that 1) catastrophizing modulates brain responses to pain anticipation, and that 2) anticipatory brain activity mediates the hyperalgesic effect of different levels of catastrophizing, in fibromyalgia (FM) patients. Using functional Magnetic Resonance Imaging, we scanned the brains of 31 FM patients exposed to visual cues anticipating the onset of moderately intense deep-tissue pain stimuli. Our results indicated the existence of a negative association between catastrophizing and pain-anticipatory brain activity, including in the right lateral prefrontal cortex (IPFC). A bootstrapped mediation analysis revealed that pain-anticipatory activity in lateral prefrontal cortex (IPFC) mediates the association between catastrophizing and pain sensitivity. These findings highlight the role of IPFC in the pathophysiology of FM related hyperalgesia, and suggest that deficits in the recruitment of pain-inhibitory brain circuitry during pain-anticipatory periods may play an important contributory role in the association between various degrees of widespread hyperalgesia in FM and levels of catastrophizing, a well validated measure of negative cognitions and psychological distress. Perspective This article highlights the presence of alterations in pain-anticipatory brain activity in FM. These findings provide the rationale for the development of psychological or neurofeedback-based techniques aimed at modifying patients' negative affect and cognitions towards pain. PMID:25937162

  19. 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.

  20. 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

  1. 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

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

    PubMed

    Kaneria, Anshuni

    2014-06-04

    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.

  3. Opioid-induced hyperalgesia: clinically relevant or extraneous research phenomenon?

    PubMed

    Tompkins, D Andrew; Campbell, Claudia M

    2011-04-01

    Opioids have become the unequivocal therapy of choice in treating many varieties of chronic pain. With the increased prescription of opioids, some unintended consequences have occurred. After prolonged opioid exposure, opioid-induced hyperalgesia (OIH), the paradoxical effect that opioid therapy may in fact enhance or aggravate preexisting pain, may occur. Over the past several decades, an increasing number of laboratory and clinical reports have suggested lowered pain thresholds and heightened atypical pain unrelated to the original perceived pain sensations as hallmarks of OIH. However, not all evidence supports the clinical importance of OIH, and some question whether the phenomenon exists at all. Here, we present a nonexhaustive, brief review of the recent literature. OIH will be reviewed in terms of preclinical and clinical evidence for and against its existence; recommendations for clinical evaluation and intervention also will be discussed.

  4. Classical conditioning and pain: conditioned analgesia and hyperalgesia.

    PubMed

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

    2014-01-01

    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.

  5. 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.

  6. Mechanism of human antibody-mediated neutralization of Marburg virus.

    PubMed

    Flyak, Andrew I; Ilinykh, Philipp A; Murin, Charles D; Garron, Tania; Shen, Xiaoli; Fusco, Marnie L; Hashiguchi, Takao; Bornholdt, Zachary A; Slaughter, James C; Sapparapu, Gopal; Klages, Curtis; Ksiazek, Thomas G; Ward, Andrew B; Saphire, Erica Ollmann; Bukreyev, Alexander; Crowe, James E

    2015-02-26

    The mechanisms by which neutralizing antibodies inhibit Marburg virus (MARV) are not known. We isolated a panel of neutralizing antibodies from a human MARV survivor that bind to MARV glycoprotein (GP) and compete for binding to a single major antigenic site. Remarkably, several of the antibodies also bind to Ebola virus (EBOV) GP. Single-particle EM structures of antibody-GP complexes reveal that all of the neutralizing antibodies bind to MARV GP at or near the predicted region of the receptor-binding site. The presence of the glycan cap or mucin-like domain blocks binding of neutralizing antibodies to EBOV GP, but not to MARV GP. The data suggest that MARV-neutralizing antibodies inhibit virus by binding to infectious virions at the exposed MARV receptor-binding site, revealing a mechanism of filovirus inhibition. PMID:25723164

  7. 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

  8. 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

  9. Resiniferatoxin (RTX) Causes a Uniquely Protracted Musculoskeletal Hyperalgesia in Mice by Activation of TRPV1 Receptors

    PubMed Central

    Abdelhamid, Ramy E.; Kovács, Katalin J.; Honda, Christopher N.; Nunez, Myra G.; Larson, Alice A.

    2013-01-01

    Inactivation of TRPV1 receptors is one approach to analgesic drug development. However, TRPV1 receptors exert different effects on each modality of pain. Because muscle pain is clinically important, we compared the effect of TRPV1 ligands on musculoskeletal nociception to that on thermal and tactile nociception. Injected parenterally, capsaicin had no effect on von Frey fiber responses (tactile) but induced a transient hypothermia and hyperalgesia in both the tail flick (thermal) and grip force (musculoskeletal) assays, presumably by its agonistic action at TRPV1 sites. In contrast, RTX produced a chronic (>58 days) thermal antinociception, consistent with its reported ability to desensitize TRPV1 sites. In the same mice, RTX produced a transient hypothermia (7 h) and a protracted (28 day) musculoskeletal hyperalgesia in spite of a 35.5% reduction in TRPV1 receptor-immunoreactivity in muscle afferents. Once musculoskeletal hyperalgesia subsided, mice were tolerant to the hyperalgesic effects of either capsaicin or RTX while tolerance to hypothermia did not develop until after three injections. Musculoskeletal hyperalgesia was prevented but not reversed by SB-366791, a TRPV1 antagonist, indicating that TRPV1 receptors initiate but do not maintain hyperalgesia. Injected intrathecally, RTX produced only a brief musculoskeletal hyperalgesia (2 days) after which mice were tolerant to this effect. Perspective The effect of TRPV1 receptors varies depending on modality and tissue type such that RTX causes thermal antinociception, musculoskeletal hyperalgesia, and no effect on tactile nociception in healthy mice. Spinal TRPV1 receptors are a potential target for pain relief as they induce only a short musculoskeletal hyperalgesia followed by desensitization. PMID:24188863

  10. Fucoidan attenuates the existing allodynia and hyperalgesia in a rat model of neuropathic pain.

    PubMed

    Hu, Chuanyin; Zhang, Guoping; Zhao, Yun-Tao

    2014-06-13

    Fucoidan is an active constituent found in brown seaweeds, which have potential neuroprotection. The current study aimed to investigate the effects of fucoidan on the maintenance of neuropathic pain induced by L5 spinal nerve ligation (SNL) and the underlying mechanism related to the spinal neuroimmune responses. Animals were randomized into 5 groups: sham-operation with vehicle and SNL with vehicle or fucoidan (15, 50, and 100mg/kg). Different doses of fucoidan or vehicle were administered intrathecally once daily from postoperative day (POD) 11-20. Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) was measured on 1 day before operation and days 10, 20, 22, 24, 26, 28, 30 after operation. Glial activation markers such as glial fibrillary acidic protein (GFAP) and macrophage antigen complex-1 (mac-1), inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 activation, and extracellular signalregulated protein kinase (ERK) activation in the lumbar spinal cord were determined on day 30 after operation. The results showed that fucoidan caused dose-dependently attenuation of mechanical allodynia and thermal hyperalgesia. Furthermore, fucoidan could markedly inhibit neuroimmune activation characterized by glial activation, production of cytokines as well as ERK activation. The analgesic effect of intrathecal fucoidan in rats receiving SNL might partly attribute to the inhibition of neuroimmune activation associated with the maintenance of neuropathic pain.

  11. 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

  12. Fas and its ligand in a general mechanism of T-cell-mediated cytotoxicity.

    PubMed Central

    Hanabuchi, S; Koyanagi, M; Kawasaki, A; Shinohara, N; Matsuzawa, A; Nishimura, Y; Kobayashi, Y; Yonehara, S; Yagita, H; Okumura, K

    1994-01-01

    To investigate the mechanisms of T-cell-mediated cytotoxicity, we estimated the involvement of apoptosis-inducing Fas molecule on the target cells and its ligand on the effector cells. When redirected by ConA or anti-CD3 monoclonal antibody, a CD4+ T-cell clone, BK1, could lyse the target cells expressing wild-type Fas molecule but not those expressing death signaling-deficient mutants. This indicates the involvement of Fas-mediated signal transduction in the target cell lysis by BK1. Anti-CD3-activated but not resting BK1 expressed Fas ligand as detected by binding of a soluble Fas-Ig fusion protein, and the BK1-mediated cytotoxicity was blocked by the addition of Fas-Ig, implicating the inducible Fas ligand in the BK1 cytotoxicity. Ability to exert the Fas-mediated cytotoxicity was not confined to BK1, but splenic CD4+ T cells and, to a lesser extent, CD8+ T cells could also exert the Fas-dependent target cell lysis. This indicates that the Fas-mediated target cell lytic pathway can be generally involved in the T-cell-mediated cytotoxicity. Interestingly, CD4+ T cells prepared from gld/gld mice did not mediate the Fas-mediated cytotoxicity, indicating defective expression of functional Fas ligand in gld mice. PMID:7515183

  13. 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

  14. 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.

  15. Molecular mechanisms of antibody-mediated neutralisation of flavivirus infection.

    PubMed

    Pierson, Theodore C; Diamond, Michael S

    2008-01-01

    Flaviviruses are a group of positive-stranded RNA viruses that cause a spectrum of severe illnesses globally in more than 50 million individuals each year. While effective vaccines exist for three members of this group (yellow fever, Japanese encephalitis, and tick-borne encephalitis viruses), safe and effective vaccines for several other flaviviruses of clinical importance, including West Nile and dengue viruses, remain in development. An effective humoral immune response is critical for protection against flaviviruses and an essential goal of vaccine development. The effectiveness of virus-specific antibodies in vivo reflects their capacity to inhibit virus entry and spread through several mechanisms, including the direct neutralisation of virus infection. Recent advances in our understanding of the structural biology of flaviviruses, coupled with the use of small-animal models of flavivirus infection, have promoted significant advances in our appreciation of the factors that govern antibody recognition and inhibition of flaviviruses in vitro and in vivo. In this review, we discuss the properties that define the potency of neutralising antibodies and the molecular mechanisms by which they inhibit virus infection. How recent advances in this area have the potential to improve the development of safe and effective vaccines and immunotherapeutics is also addressed. PMID:18471342

  16. Molecular mechanisms of antibody-mediated neutralisation of flavivirus infection.

    PubMed

    Pierson, Theodore C; Diamond, Michael S

    2008-01-01

    Flaviviruses are a group of positive-stranded RNA viruses that cause a spectrum of severe illnesses globally in more than 50 million individuals each year. While effective vaccines exist for three members of this group (yellow fever, Japanese encephalitis, and tick-borne encephalitis viruses), safe and effective vaccines for several other flaviviruses of clinical importance, including West Nile and dengue viruses, remain in development. An effective humoral immune response is critical for protection against flaviviruses and an essential goal of vaccine development. The effectiveness of virus-specific antibodies in vivo reflects their capacity to inhibit virus entry and spread through several mechanisms, including the direct neutralisation of virus infection. Recent advances in our understanding of the structural biology of flaviviruses, coupled with the use of small-animal models of flavivirus infection, have promoted significant advances in our appreciation of the factors that govern antibody recognition and inhibition of flaviviruses in vitro and in vivo. In this review, we discuss the properties that define the potency of neutralising antibodies and the molecular mechanisms by which they inhibit virus infection. How recent advances in this area have the potential to improve the development of safe and effective vaccines and immunotherapeutics is also addressed.

  17. 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

  18. Evodiamine suppresses capsaicin-induced thermal hyperalgesia through activation and subsequent desensitization of the transient receptor potential V1 channels.

    PubMed

    Iwaoka, Emiko; Wang, Shenglan; Matsuyoshi, Nobuyuki; Kogure, Yoko; Aoki, Shunji; Yamamoto, Satoshi; Noguchi, Koichi; Dai, Yi

    2016-01-01

    Evodiae fructus (EF), a fruit of Evodia rutaecarpa Bentham, has long been used as an analgesic drug in traditional Chinese and Japanese medicine. However, the underlying molecular mechanism of its pharmacological action is unclear. Here, using calcium imaging, whole-cell patch-clamp recording, and behavioral analysis, we investigated the pharmacological action of EF and its principal compound, evodiamine, on the transient receptor potential (TRP) V1 channels. Dorsal root ganglion (DRG) neurons and TRPV1- or TRPA1-transfected human embryonic kidney-derived (HEK) 293 cells were used for calcium imaging or whole-cell patch-clamp recording. Twenty male adult Sprague-Dawley rats were used for the capsaicin-induced thermal hyperalgesia behavioral analyses. We found that evodiamine induced significant increases in intracellular calcium and robust inward currents in a subpopulation of isolated rat DRG neurons, most of which were also sensitive to capsaicin. The effect of evodiamine was completely blocked by capsazepine, a competitive antagonist of TRPV1. Evodiamine induced significant inward currents in TRPV1-, but not TRPA1-transfected HEK293 cells. Pretreatment with evodiamine reduced capsaicin-induced currents significantly. Furthermore, the in vivo pre-treatment of evodiamine suppressed thermal hyperalgesia induced by intraplantar injection of capsaicin in rats. These results identify that the analgesic effect of EF and evodiamine may be due to the activation and subsequent desensitization of TRPV1 in sensory neurons.

  19. 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

  20. Discovering mechanisms of signaling-mediated cysteine oxidation.

    PubMed

    Poole, Leslie B; Nelson, Kimberly J

    2008-02-01

    Accumulating evidence reveals hydrogen peroxide as a key player both as a damaging agent and, from emerging evidence over the past decade, as a second messenger in intracellular signaling. This rather mild oxidant acts upon downstream targets within signaling cascades to modulate the activity of a host of enzymes (e.g. phosphatases and kinases) and transcriptional regulators through chemoselective oxidation of cysteine residues. With the recent development of specific detection reagents for hydrogen peroxide and new chemical tools to detect the generation of the initial oxidation product, sulfenic acid, on reactive cysteines within target proteins, the scene is set to gain a better understanding of the mechanisms through which hydrogen peroxide acts as a second messenger in cell signaling.

  1. 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

  2. Mechanisms of Gadographene-Mediated Proton Spin Relaxation

    PubMed Central

    Hung, Andy H.; Duch, Matthew C.; Parigi, Giacomo; Rotz, Matthew W.; Manus, Lisa M.; Mastarone, Daniel J.; Dam, Kevin T.; Gits, Colton C.; MacRenaris, Keith W.; Luchinat, Claudio; Hersam, Mark C.; Meade, Thomas J.

    2013-01-01

    Gd(III) associated with carbon nanomaterials relaxes water proton spins at an effectiveness that approaches or exceeds the theoretical limit for a single bound water molecule. These Gd(III)-labeled materials represent a potential breakthrough in sensitivity for Gd(III)-based contrast agents used for magnetic resonance imaging (MRI). However, their mechanism of action remains unclear. A gadographene library encompassing GdCl3, two different Gd(III)-complexes, graphene oxide (GO), and graphene suspended by two different surfactants and subjected to varying degrees of sonication was prepared and characterized for their relaxometric properties. Gadographene was found to perform comparably to other Gd(III)-carbon nanomaterials; its longitudinal (r1) and transverse (r2) relaxivity is modulated between 12–85 mM−1s−1 and 24–115 mM−1s−1, respectively, depending on the Gd(III)-carbon backbone combination. The unusually large relaxivity and its variance can be understood under the modified Florence model incorporating the Lipari-Szabo approach. Changes in hydration number (q), water residence time (τM), molecular tumbling rate (τR), and local motion (τfast) sufficiently explain most of the measured relaxivities. Furthermore, results implicated the coupling between graphene and Gd(III) as a minor contributor to proton spin relaxation. PMID:24298299

  3. Mechanisms underlying heterologous skin scaffold-mediated tissue remodeling

    PubMed Central

    Mimura, Kallyne K. O.; Moraes, Andréia R.; Miranda, Aline C.; Greco, Rebecca; Ansari, Tahera; Sibbons, Paul; Greco, Karin V.; Oliani, Sonia M.

    2016-01-01

    Biocompatibility of two newly developed porcine skin scaffolds was assessed after 3, 14, 21 and 90 days of implantation in rats. Both scaffolds showed absence of cells, preservation of ECM and mechanical properties comparable to non-decellularised skin before implantation. Host cell infiltration was much prominent on both scaffolds when compared to Permacol (surgical control). At day 3, the grafts were surrounded by polymorphonuclear cells, which were replaced by a notable number of IL-6-positive cells at day 14. Simultaneously, the number of pro-inflammatory M1-macrophage was enhanced. Interestingly, a predominant pro-remodeling M2 response, with newly formed vessels, myofibroblasts activation and a shift on the type of collagen expression was sequentially delayed (around 21 days). The gene expression of some trophic factors involved in tissue remodeling was congruent with the cellular events. Our findings suggested that the responsiveness of macrophages after non-crosslinked skin scaffolds implantation seemed to intimately affect various cell responses and molecular events; and this range of mutually reinforcing actions was predictive of a positive tissue remodeling that was essential for the long-standing success of the implants. Furthermore, our study indicates that non-crosslinked biologic scaffold implantation is biocompatible to the host tissue and somehow underlying molecular events involved in tissue repair. PMID:27725772

  4. 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

  5. Capsaicin avoidance as a measure of chemical hyperalgesia in orofacial nerve injury models.

    PubMed

    Boucher, Yves; Carstens, Mirela Iodi; Sawyer, Carolyn M; Zanotto, Karen L; Merrill, Austin W; Carstens, E

    2013-05-24

    Many patients suffer from trigeminal neuralgia and other types of orofacial pain that are poorly treated, necessitating preclininal animal models for development of mechanisms-based therapies. The present study assessed capsaicin avoidance and other nocifensive behavioral responses in three models of orofacial nerve injury in rats: chronic constriction injury (CCI) of the mental nerves, partial tight ligation of mental nerves, and CCI of lingual nerves. We additionally investigated if nerve injury resulted in enhanced capsaicin-evoked activation of neurons in trigeminal caudalis (Vc) or nucleus of the solitary tract (NTS) based on expression of Fos-like immunoreactivity (FLI). Mental nerve CCI resulted in an enhancement of capsaicin avoidance in a two-bottle preference paradigm, while neither mental nerve injury produced thermal hyperalgesia or mechanical allodynia. CCI of lingual nerves did not affect capsaicin avoidance. Counts of FLI in Vc were significantly higher in the lingual sham and mental nerve CCI groups compared to mental shams; FLI counts in NTS did not differ among groups. Mental nerve CCI may have induced central sensitization of chemical nociception since increased capsaicin avoidance was accompanied by greater activation of Vc neurons in response to oral capsaicin.

  6. 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.

  7. 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.

  8. 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

  9. Another look at safety climate and safety behavior: deepening the cognitive and social mediator mechanisms.

    PubMed

    Fugas, Carla S; Silva, Sílvia A; Meliá, José L

    2012-03-01

    In this study, safety climate literature and the theory of planned behavior were combined to explore the cognitive and social mechanisms that mediate the relationship between organizational safety climate and compliance and proactive safety behaviors. The sample consisted of 356 workers from a transportation organization. Using a multiple mediation design, the results revealed that proactive and compliance safety behaviors are explained by different patterns of combinations of individual and situational factors related to safety. On the one hand, the relationship between organizational safety climate and proactive safety behaviors was mediated by coworkers' descriptive norms and attitudes toward safety. On the other hand, supervisors' injunctive safety norms and perceived behavioral control were the mediator variables between organizational safety climate and compliance safety behaviors. Theoretical and practical implications of the findings are discussed.

  10. Another look at safety climate and safety behavior: deepening the cognitive and social mediator mechanisms.

    PubMed

    Fugas, Carla S; Silva, Sílvia A; Meliá, José L

    2012-03-01

    In this study, safety climate literature and the theory of planned behavior were combined to explore the cognitive and social mechanisms that mediate the relationship between organizational safety climate and compliance and proactive safety behaviors. The sample consisted of 356 workers from a transportation organization. Using a multiple mediation design, the results revealed that proactive and compliance safety behaviors are explained by different patterns of combinations of individual and situational factors related to safety. On the one hand, the relationship between organizational safety climate and proactive safety behaviors was mediated by coworkers' descriptive norms and attitudes toward safety. On the other hand, supervisors' injunctive safety norms and perceived behavioral control were the mediator variables between organizational safety climate and compliance safety behaviors. Theoretical and practical implications of the findings are discussed. PMID:22269531

  11. 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.

  12. Differential pharmacological alleviation of oxaliplatin-induced hyperalgesia/allodynia at cephalic versus extra-cephalic level in rodents.

    PubMed

    Michot, Benoit; Kayser, Valérie; Bastian, Gérard; Bourgoin, Sylvie; Hamon, Michel

    2014-04-01

    Previous data showed that neuropathic pain induced by mechanical lesion of peripheral nerves responds differently to alleviating drugs at cephalic versus extracephalic level. Because neuropathic pain evoked by anti-cancer drugs differs from that triggered by mechanical nerve lesion, we investigated whether differences between cephalic and extracephalic levels could also be characterized in rodents rendered neuropathic by treatment with the anti-cancer platinum derivative oxaliplatin. C57BL/6J mice received two injections and Sprague-Dawley rats three injections of oxaliplatin (10 mg/kg, i.p.) or its vehicle, with three days intervals. Supersensitivity to mechanical (von Frey filaments), cold (acetone drop) and chemical/inflammatory (formalin) stimulations was assessed in vibrissae and hindpaw territories. Transcripts of neuroinflammatory markers were quantified by real-time RT-qPCR in rat ganglia and central tissues. Oxaliplatin induced mechanical allodynia, cold hyperalgesia and chemical/inflammatory supersensitivity at both hindpaw and vibrissal levels in mice and rats. Acute treatment with gabapentin (30 mg/kg i.p.), morphine (3 mg/kg s.c.) or the 5-HT1A receptor agonist 8-OH-DPAT (0.16 mg/kg s.c.) significantly reduced oxaliplatin-induced supersensitivity in hindpaw but not vibrissal territory. In contrast, the antimigraine drugs naratriptan (0.1 mg/kg s.c.) and olcegepant (0.6 mg/kg i.v.) decreased oxaliplatin-induced supersensitivity in vibrissal territory only. Among the various markers investigated, only TRPA1 transcript was upregulated in ganglia of oxaliplatin-treated rats. These data showed that oxaliplatin induced supersensitivity to various stimuli in both cephalic and extra-cephalic territories in rodents. Regional differences in the efficacy of drugs to alleviate oxaliplatin-induced allodynia/hyperalgesia further support the idea that mechanisms underlying neuropathic pain have peculiarities at cephalic versus extra-cephalic level.

  13. Inhibition of spinal constitutive NOS-2 by 1400W attenuates tissue injury and inflammation-induced hyperalgesia and spinal p38 activation.

    PubMed

    Tang, Qingbo; Svensson, Camilla I; Fitzsimmons, Bethany; Webb, Michael; Yaksh, Tony L; Hua, Xiao-Ying

    2007-05-01

    Nitric oxide (NO) and its synthesizing enzymes, including NO synthase-2 (NOS-2, also called inducible NOS, iNOS), have been implicated in spinal nociception. 1400W is a highly selective NOS-2 inhibitor, as compared with either NOS-1 (neuronal NOS, nNOS) or NOS-3 (endothelial NOS). Here we examined the anti-nociceptive effects of intrathecal (IT) administration of 1400W in two experimental models of hyperalgesia (formalin and carrageenan models), in addition to the effect of 1400W on stimulation-induced activation of spinal p38 mitogen-activated protein kinase (p38). IT treatment of rats with 1400W produced a dose-dependent inhibition of paw formalin-induced phase II flinches, and attenuated carrageenan-induced thermal hyperalgesia. In contrast, IT injection of a selective inhibitor of NOS-1, nNOS inhibitor-I, had no effect in either model. Furthermore, 1400W at a dose that suppressed formalin-induced flinching behavior also blocked formalin-evoked p38 phosphorylation (activation) in the spinal cord, while nNOS inhibitor-I displayed no activity. The prompt effects of IT 1400W suggest involvement of constitutively expressed NOS-2 in spinal nociception. The NOS-2 protein in rat spinal cords was undetectable by Western blotting. However, when the protein was immunoprecipitated prior to Western blotting, NOS-2-immunoreactive bands were detected in the tissues, including naïve spinal cords. The presence of constitutive spinal NOS-2 was further confirmed by reverse transcriptase-polymerase chain reaction. Taken together, the present studies suggest that constitutively expressed spinal NOS-2 mediates tissue injury and inflammation-induced hyperalgesia, and that activation of p38 is one of the downstream factors in NO-mediated signaling in the initial processing of spinal nociception.

  14. 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

  15. Clinical interpretation of opioid tolerance versus opioid-induced hyperalgesia.

    PubMed

    Chen, Lucy; Sein, Michael; Vo, Trang; Amhmed, Shihab; Zhang, Yi; Hilaire, Kristin St; Houghton, Mary; Mao, Jianren

    2014-01-01

    Opioid analgesics are commonly used to manage moderate to severe pain. However, the long-term use of opioids could lead to opioid tolerance (OT) and opioid-induced hyperalgesia (OIH). Distinguishing OIH from OT would impact the practice of opioid therapy because opioid dose adjustment may differentially influence OT and OIH. Currently, there are no standard criteria of OT versus OIH causing considerable ambiguity in clinical interpretation and management of these conditions. The authors designed a practitioner-based survey consisting of 20 targeted questions. Answering these questions would require responders' actual clinical experiences with opioid therapy. The survey was conducted between 2011 and 2012 through direct mails or e-mails to 1,408 physicians who are currently practicing in the United States. The authors find that certain clinical characteristics (eg, increased pain despite opioid dose escalation) are often used by practitioners to make differential diagnosis of OT and OIH despite some overlap in their clinical presentation. A key difference in clinical outcome is that OT and OIH could be improved and exacerbated by opioid dose escalation, respectively. Our survey results revealed a significant knowledge gap in some responders regarding differential diagnosis and management of OT and OIH. The results also identified several issues, such as opioid dose adjustment and clinical comorbidities related to OT and OIH, which require future patient-based studies.

  16. Targeting Opioid-Induced Hyperalgesia in Clinical Treatment: Neurobiological Considerations.

    PubMed

    Arout, Caroline A; Edens, Ellen; Petrakis, Ismene L; Sofuoglu, Mehmet

    2015-06-01

    Opioid analgesics have become a cornerstone in the treatment of moderate to severe pain, resulting in a steady rise of opioid prescriptions. Subsequently, there has been a striking increase in the number of opioid-dependent individuals, opioid-related overdoses, and fatalities. Clinical use of opioids is further complicated by an increasingly deleterious profile of side effects beyond addiction, including tolerance and opioid-induced hyperalgesia (OIH), where OIH is defined as an increased sensitivity to already painful stimuli. This paradoxical state of increased nociception results from acute and long-term exposure to opioids, and appears to develop in a substantial subset of patients using opioids. Recently, there has been considerable interest in developing an efficacious treatment regimen for acute and chronic pain. However, there are currently no well-established treatments for OIH. Several substrates have emerged as potential modulators of OIH, including the N-methyl-D-aspartate and γ-aminobutyric acid receptors, and most notably, the innate neuroimmune system. This review summarizes the neurobiology of OIH in the context of clinical treatment; specifically, we review evidence for several pathways that show promise for the treatment of pain going forward, as prospective adjuvants to opioid analgesics. Overall, we suggest that this paradoxical state be considered an additional target of clinical treatment for chronic pain.

  17. Effects of ginsenosides on opioid-induced hyperalgesia in mice.

    PubMed

    Li, Peng; Tang, Minke; Li, Hui; Huang, Xinjie; Chen, Lei; Zhai, Haifeng

    2014-07-01

    Opioid-induced hyperalgesia (OIH) is characterized by nociceptive sensitization caused by the cessation of chronic opioid use. OIH can limit the clinical use of opioid analgesics and complicate withdrawal from opioid addiction. In this study, we investigated the effects of Re, Rg1, and Rb1 ginsenosides, the bioactive components of ginseng, on OIH. OIH was achieved in mice after subcutaneous administration of morphine for 7 consecutive days three times per day. During withdrawal (days 8 and 9), these mice were administered Re, Rg1, or Rb1 intragastrically two times per day. On the test day (day 10), mice were subjected to the thermal sensitivity test and the acetic acid-induced writhing test. Re (300 mg/kg) inhibited OIH in both the thermal sensitivity test and the acetic acid-induced writhing test. However, the Rg1 and Rb1 ginsenosides failed to prevent OIH in either test. Furthermore, Rg1 showed a tendency to aggravate OIH in the acetic acid-induced writhing test. Our data suggested that the ginsenoside Re, but not Rg1 or Rb1, may contribute toward reversal of OIH.

  18. Intradermal glutamate and capsaicin injections: intra- and interindividual variability of provoked hyperalgesia and allodynia.

    PubMed

    Nilsson, Matias; Lassen, Dorte; Andresen, Trine; Nielsen, Anders K; Arendt-Nielsen, Lars; Drewes, Asbjørn M

    2014-06-01

    Intradermal injections of glutamate and capsaicin are attractive to use in human experimental pain models because hyperalgesia and allodynia mimic isolated aspects of clinical pain disorders. The aim of the present study was to investigate the reproducibility of these models. Twenty healthy male volunteers (mean age 24 years; range 18-38 years) received intradermal injections of glutamate and capsaicin in the volar forearm. Magnitudes of secondary pinprick hyperalgesia and brush-evoked allodynia were investigated using von Frey filaments (gauges 10, 15, 60 and 100 g) and brush strokes. Areas of secondary hyperalgesia and allodynia were quantified immediately after injection and after 15, 30 and 60 min. Two identical experiments separated by at least 7 days were performed. Reproducibility across and within volunteers (inter- and intra-individual variation, respectively) was assessed using intraclass correlation coefficient (ICC) and coefficient of variation (CV). Secondary pinprick hyperalgesia was observed as a marked increase in the visual analogue scale (VAS) response to von Frey gauges 60 and 100 g (P < 0.001) after glutamate injection. For capsaicin, secondary pinprick hyperalgesia was detected with all von Frey gauges (P < 0.001). Glutamate evoked reproducible VAS response to all von Frey gauges (ICC > 0.60) and brush strokes (ICC > 0.83). Capsaicin injection was reproducible for secondary hyperalgesia (ICC > 0.70) and allodynia (ICC > 0.71). Intra-individual variability was generally lower for the VAS response to von Frey and brush compared with areas of secondary hyperalgesia and allodynia. In conclusion, glutamate and capsaicin yield reproducible hyperalgesic and allodynic responses, and the present model is well suited for basic research, as well as for assessing the modulation of central phenomena.

  19. 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…

  20. 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.

  1. 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…

  2. 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…

  3. 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…

  4. Snake venom components enhance pain upon subcutaneous injection: an initial examination of spinal cord mediators.

    PubMed

    Chacur, Marucia; Gutiérrez, José Maria; Milligan, Erin D; Wieseler-Frank, Julie; Britto, Luiz R G; Maier, Steven F; Watkins, Linda R; Cury, Yara

    2004-09-01

    Snakebites are a relevant public health problem in Central and South America. Snake bite envenomations cause intense pain, not relieved by anti-venom. The fangs of many species are short, causing subcutaneous injection. Fangs of larger species inflict subcutaneous or intramuscular envenomation. To understand pain induced by subcutaneous venom, this study examined spinal mechanisms involved in pain-enhancing effects of subcutaneous Lys49 and Asp49 secretory phospholipase-A(2) (sPLA2), two components of Bothrops asper snake venom showing highly different enzymatic activities. Unilateral intraplantar sPLA2-Lys49 (catalytically inactive) or sPLA2-Asp49 (catalytically active) into rat hindpaws each induced mechanical hyperalgesia (Randall-Selitto test), whereas only catalytically active sPLA2-Asp49 caused mechanical allodynia (von Frey test). Effects induced by both sPLA2s were inhibited by intrathecal fluorocitrate, a reversible glial metabolic inhibitor. In support, immunohistochemical analysis revealed activation of dorsal horn astrocytes and microglia after intraplantar injection of either sPLA2. Spinal proinflammatory cytokines, nitric oxide, and prostanoids each appear to be involved in the pain-enhancing effects of these sPLA2s. Blockade of interleukin-1 (IL1) inhibited hyperalgesia induced by both sPLA2s, while leaving allodynia unaffected. Blockade of tumor necrosis factor reduced responses to sPLA2-Asp49. An inhibitor of neuronal nitric oxide synthase, 7-nitroindazole (7-NI), inhibited hyperalgesia induced by both sPLA2s, without interfering with allodynia induced by sPLA2-Asp49. On the other hand, L-N(6)-(1-iminoethyl)lysine (L-NI), an inhibitor of the inducible nitric oxide synthase, did not alter any sPLA2-induced effect. Lastly, celecoxib, an inhibitor of cyclooxygenase-2, attenuated sPLA2 actions. These data provide the first evidence of spinal mediators involved in pain facilitation induced by subcutaneous venoms.

  5. 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

  6. Abundant genetic overlap between blood lipids and immune-mediated diseases indicates shared molecular genetic mechanisms.

    PubMed

    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 G; 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. Abundant genetic overlap between blood lipids and immune-mediated diseases indicates shared molecular genetic mechanisms.

    PubMed

    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 G; 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.

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

    PubMed Central

    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

  9. Mechanical strain promotes osteoblastic differentiation through integrin-β1-mediated β-catenin signaling.

    PubMed

    Yan, Yuxian; Sun, Haoyang; Gong, Yuanwei; Yan, Zhixiong; Zhang, Xizheng; Guo, Yong; Wang, Yang

    2016-08-01

    As integrins are mechanoresponsive, there exists an intimate relationship between integrins and mechanical strain. Integrin-β1 mediates the impact of mechanical strain on bone. Mechanical strain induces bone formation through the activation of β-catenin pathways, which suggests that integrin-β1 mediates β-catenin signaling in osteoblasts in response to mechanical strain. In the present study, we examined the role of integrin-β1 in Wnt/β-catenin signal transduction in mechanically strained osteoblasts. MC3T3-E1 osteoblastic cells were transfected with integrin-β1 small interfering RNA (si-Itgβ1), and exposed to mechanical tensile strain of 2,500 microstrain (µε) using a four-point bending device. The mechanical strain enhanced the mRNA expression of integrin-β1, the protein levels of phosphorylated (p-) glycogen synthase kinase-3β (GSK‑3β) and β-catenin, simultaneously increased the mRNA levels of runt-related transcriptional factor 2 (Runx2) and osteocalcin (OCN), the protein levels of bone morphogenetic protein (BMP)-2 and -4 and enhanced the alkaline phosphatase (ALP) activity of the ME3T3-E1 cells. The elevations were inhibited by si-Itgβ1. Additionally, the mechanical strain induced the nuclear translocation of β-catenin into the nucleus, which was also inhibited by si-Itgβ1. These findings indicated that mechanical strain promoted osteoblastic differentiation through integrin‑β1‑mediated β-catenin signaling.

  10. URB597, an inhibitor of fatty acid amide hydrolase, reduces hyperalgesia in diabetic rats.

    PubMed

    Hasanein, Parisa; Parviz, Mohsen; Keshavarz, Mansoor; Roohbakhsh, Ali

    2009-06-01

    Diabetic rats display increased pain responses after injection of formalin into the paw or thermal stimulation of the tail, suggesting the presence of hyperalgesia. In this study, we investigated the efficacy of URB597 (0.1, 0.3, and 0.5 mg/kg, i.p.), an inhibitor of endocannabinoids metabolism, on 2 models of experimental hyperalgesia in streptozotocin (STZ)-induced diabetic rats. Animals were divided into control, URB597-treated control (0.1, 0.3, and 0.5 mg/kg), diabetic, and URB597-treated diabetic (0.1, 0.3, and 0.5 mg/kg) groups. Formalin and tail-flick tests were performed 4 and 8 weeks after the onset of hyperglycemia, respectively. Diabetes caused significant hyperalgesia during these tests. URB597 (0.3 and 0.5 mg/kg) reversed chemical and thermal hyperalgesia in diabetic rats. Administration of URB597 at a dose of 0.1 mg/kg did not alter pain-related behaviors in control and diabetic groups compared with those of the respective control groups. URB597 treatment did not affect body weight or plasma glucose level of treated animals compared with nontreated animals. This study shows that increasing endocannabinoid neurotransmission with URB597 displays efficacy in chemical and thermal models of diabetic hyperalgesia. It also suggests that URB597 is a promising tool for treatment of painful diabetic neuropathy.

  11. Abdominal pain in Irritable Bowel Syndrome: a review of putative psychological, neural and neuro-immune mechanisms.

    PubMed

    Elsenbruch, Sigrid

    2011-03-01

    Chronic abdominal pain is a common symptom of great clinical significance in several areas of medicine. In many cases no organic cause can be established resulting in the classification as functional gastrointestinal disorder. Irritable Bowel Syndrome (IBS) is the most common of these conditions and is considered an important public health problem because it can be disabling and constitutes a major social and economic burden given the lack of effective treatments. IBS aetiology is most likely multi-factorial involving biological, psychological and social factors. Visceral hyperalgesia (or hypersensitivity) and visceral hypervigilance, which could be mediated by peripheral, spinal, and/or central pathways, constitute key concepts in current research on pathophysiological mechanisms of visceral hyperalgesia. The role of central nervous system mechanisms along the "brain-gut axis" is increasingly appreciated, owing to accumulating evidence from brain imaging studies that neural processing of visceral stimuli is altered in IBS together with long-standing knowledge regarding the contribution of stress and negative emotions to symptom frequency and severity. At the same time, there is also growing evidence suggesting that peripheral immune mechanisms and disturbed neuro-immune communication could play a role in the pathophysiology of visceral hyperalgesia. This review presents recent advances in research on the pathophysiology of visceral hyperalgesia in IBS, with a focus on the role of stress and anxiety in central and peripheral response to visceral pain stimuli. Together, these findings support that in addition to lower pain thresholds displayed by a significant proportion of patients, the evaluation of pain appears to be altered in IBS. This may be attributable to affective disturbances, negative emotions in anticipation of or during visceral stimulation, and altered pain-related expectations and learning processes. Disturbed "top-down" emotional and cognitive pain

  12. Isolation rearing reduces mechanical allodynia in a mouse model of chronic inflammatory pain.

    PubMed

    Horiguchi, Naotaka; Ago, Yukio; Hasebe, Shigeru; Higashino, Kosuke; Asada, Kazuki; Kita, Yuki; Takuma, Kazuhiro; Matsuda, Toshio

    2013-11-15

    Social isolation rearing in mice after weaning reduces pain sensitivity to acute pain, and this hypoalgesia is mediated by the descending serotonergic pain inhibitory system in which the spinal serotonin (5-HT)1A receptor is involved. However, it is not known whether isolation rearing affects pain sensitivity to neuropathic or inflammatory chronic pain. In this study, we examined the effects of isolation rearing on chronic pain induced by Freund's complete adjuvant (FCA) and partial sciatic nerve ligation using the von Frey test (to assess mechanical allodynia) and the plantar test (to assess thermal hyperalgesia). In the FCA model, isolation rearing reduced mechanical allodynia, but not thermal hyperalgesia. In contrast, isolation rearing had no effect on allodynia or hyperalgesia in the sciatic nerve ligation model. The isolation rearing-induced inhibition of allodynia was alleviated by intrathecal injection of WAY100635, a selective 5-HT1A receptor antagonist. FCA increased 5-HT turnover and decreased 5-HT1A receptor expression in the spinal cord of group-reared mice, while it did not have these effects in isolation-reared mice. These results suggest that FCA suppresses the serotonergic pain inhibitory system selectively in group-reared mice. Moreover, systemic administration of osemozotan, a selective 5-HT1A receptor agonist, inhibited FCA-induced mechanical allodynia in group-reared mice, and this effect of the drug was suppressed by intrathecal injection of WAY100635. Collectively, these findings suggest that isolation rearing selectively reduces FCA-induced mechanical allodynia in mice and that this effect is mediated by the activation of spinal 5-HT1A receptors.

  13. 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

  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 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

  15. 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.

  16. 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

  17. Pressure Pain Sensitivity in Patients With Suspected Opioid-Induced Hyperalgesia

    PubMed Central

    Wasserman, Ronald A.; Hassett, Afton L.; Harte, Steven E.; Goesling, Jenna; Malinoff, Herbert L.; Berland, Daniel W.; Zollars, Jennifer; Moser, Stephanie E.; Brummett, Chad M.

    2015-01-01

    Background and Objectives This study was designed to test whether a brief quantitative sensory testing (QST) assessment could be used to detect hyperalgesia in patients with suspected opioid-induced hyperalgesia. Methods Twenty patients on long-term opioid therapy with suspected opioid-induced hyperalgesia were recruited along with and 20 healthy controls. Pressure pain threshold, Pain50, a measure of intermediate suprathreshold pressure pain sensitivity, and tolerance levels, were evaluated. As a secondary outcome, changes in pressure pain sensitivity following intravenous administration of placebo (saline) and fentanyl (1.5 μg/kg) were assessed. Results There were no significant differences in pain measures between healthy controls and patients. However, there was an association between higher doses of opioids and having a lower pain tolerance (r= -0.46, P=0.041) and lower Pain50 (r=-0.46, P = 0.044), which was consistent with the hypothesis. Patients on >100 mg oral morphine equivalents (OME) displayed decreased pressure pain tolerance compared to patients taking <100 mg OME (P = 0.042). In addition, male patients showed a hyperalgesic response to fentanyl administration, which was significant for the Pain50 measure (P=0.002). Conclusions Whereas there were no differences between patients suspected of having opioid-induced hyperalgesia and the healthy controls, the finding that higher doses of opioids were associated with more sensitivity suggests that dose might be an important factor in the development of hyperalgesia. In addition, male patients demonstrated a hyperalgesic response after a bolus of fentanyl. Future studies are needed to develop better diagnostics for detecting hyperalgesia in the clinical setting. PMID:26469365

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

    PubMed Central

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

    2015-01-01

    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 redoxsensing 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

  19. 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.

  20. Intraepidermal nerve fiber loss corresponds to the development of taxol-induced hyperalgesia and can be prevented by treatment with minocycline.

    PubMed

    Boyette-Davis, J; Xin, W; Zhang, H; Dougherty, P M

    2011-02-01

    Loss of intraepidermal nerve fibers (IENFs) has been speculated to play a critical role in the development of various neuropathies. In this study, the density of IENFs were studied over time during the induction of Taxol (Bristol-Myers Squibb, NY, USA)-induced chemoneuropathy and compared with the changes in IENFs in animals co-treated with Taxol plus the protective agent minocycline. Rats were injected (intraperitoneally) with 2mg/kg of Taxol every other day for four injections (day 1, 3, 5, and 7). Minocycline (25mg/kg) was given in a separate group of rats 24h prior to the first dose of Taxol and every day for the next 9days (day 0 through 9). Animals were tested for mechanical paw withdrawal thresholds prior to any drug administrations and again on day 7, 14, and 30. Immunohistochemistry using the pan-neuronal marker protein gene product 9.5 was performed on glabrous skin of the hind-paw foot pad to stain for IENFs also on day 7, 14, and 30. The results show that Taxol-treated animals developed mechanical sensitivity and corresponding IENF loss. Animals receiving minocycline plus Taxol showed no hyperalgesia or loss of IENFs. This study confirms, for the first time, that a loss of IENFs occurs as a neuropathy develops, and further shows a protection against both IENF loss and hyperalgesia with minocycline treatment. The progression of Taxol-induced mechanical hypersensitivity coincides with loss of intraepidermal nerve fibers, and the hyperalgesia and nerve fiber loss were prevented with minocycline treatment.

  1. 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.

  2. Nanoscale imaging and mechanical analysis of Fc receptor-mediated macrophage phagocytosis against cancer cells.

    PubMed

    Li, Mi; Liu, Lianqing; Xi, Ning; Wang, Yuechao; Xiao, Xiubin; Zhang, Weijing

    2014-02-18

    Fc receptor-mediated macrophage phagocytosis against cancer cells is an important mechanism in the immune therapy of cancers. Traditional research about macrophage phagocytosis was based on optical microscopy, which cannot reveal detailed information because of the 200-nm-resolution limit. Quantitatively investigating the macrophage phagocytosis at micro- and nanoscale levels is still scarce. The advent of atomic force microscopy (AFM) offers an excellent analytical instrument for quantitatively investigating the biological processes at single-cell and single-molecule levels under native conditions. In this work, we combined AFM and fluorescence microscopy to visualize and quantify the detailed changes in cell morphology and mechanical properties during the process of Fc receptor-mediated macrophage phagocytosis against cancer cells. Lymphoma cells were discernible by fluorescence staining. Then, the dynamic process of phagocytosis was observed by time-lapse optical microscopy. Next, AFM was applied to investigate the detailed cellular behaviors during macrophage phagocytosis under the guidance of fluorescence recognition. AFM imaging revealed the distinct features in cellular ultramicrostructures for the different steps of macrophage phagocytosis. AFM cell mechanical property measurements indicated that the binding of cancer cells to macrophages could make macrophages become stiffer. The experimental results provide novel insights in understanding the Fc-receptor-mediated macrophage phagocytosis.

  3. 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

  4. 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.

  5. Cell-mediated BMP-2 liberation promotes bone formation in a mechanically unstable implant environment.

    PubMed

    Hägi, Tobias T; Wu, Gang; Liu, Yuelian; Hunziker, Ernst B

    2010-05-01

    The flexible alloplastic materials that are used in bone-reconstruction surgery lack the mechanical stability that is necessary for sustained bone formation, even if this process is promoted by the application of an osteogenic agent, such as BMP-2. We hypothesize that if BMP-2 is delivered gradually, in a cell-mediated manner, to the surgical site, then the scaffolding material's lack of mechanical stability becomes a matter of indifference. Flexible discs of Ethisorb were functionalized with BMP-2, which was either adsorbed directly onto the material (rapid release kinetics) or incorporated into a calcium-phosphate coating (slow release kinetics). Unstabilized and titanium-plate-stabilized samples were implanted subcutaneously in rats and retrieved up to 14 days later for a histomorphometric analysis of bone and cartilage volumes. On day 14, the bone volume associated with titanium-plate-stabilized discs bearing an adsorbed depot of BMP-2 was 10-fold higher than that associated with their mechanically unstabilized counterparts. The bone volume associated with discs bearing a coating-incorporated depot of BMP-2 was similar in the mechanically unstabilized and titanium-plate-stabilized groups, and comparable to that associated with the titanium-plate-stabilized discs bearing an adsorbed depot of BMP-2. Hence, if an osteogenic agent is delivered in a cell-mediated manner (via coating degradation), ossification can be promoted even within a mechanically unstable environment.

  6. Substrate-mediated proton relay mechanism for the religation reaction in topoisomerase II.

    PubMed

    Hanaoka, Kyohei; Shoji, Mitsuo; Kondo, Daiki; Sato, Akimasa; Yang, Moon Young; Kamiya, Katsumasa; Shiraishi, Kenji

    2014-01-01

    The DNA religation reaction of yeast type II topoisomerase (topo II) was investigated to elucidate its metal-dependent general acid/base catalysis. Quantum mechanical/molecular mechanical calculations were performed for the topo II religation reaction, and the proton transfer pathway was examined. We found a substrate-mediated proton transfer of the topo II religation reaction, which involves the 3' OH nucleophile, the reactive phosphate, water, Arg781, and Tyr782. Metal A stabilizes the transition states, which is consistent with a two-metal mechanism in topo II. This pathway may be required for the cleavage/religation reaction of topo IA and II and will provide a general explanation for the catalytic mechanism in the topo IA and II.

  7. 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.

  8. TMPRSS2, a novel membrane-anchored mediator in cancer pain.

    PubMed

    Lam, David K; Dang, Dongmin; Flynn, Andrea N; Hardt, Markus; Schmidt, Brian L

    2015-05-01

    More than half of all cancer patients have significant pain during the course of their disease. The strategic localization of TMPRSS2, a membrane-bound serine protease, on the cancer cell surface may allow it to mediate signal transduction between the cancer cell and its extracellular environment. We show that TMPRSS2 expression is not only dramatically increased in the primary cancers of patients but TMPRSS2 immunopositivity is also directly correlated with cancer pain severity in these patients. TMPRSS2 induced proteolytic activity, activated trigeminal neurons, and produced marked mechanical hyperalgesia when administered into the hind paw of wild-type mice but not PAR2-deficient mice. Coculture of human cancer cells with murine trigeminal neurons demonstrated colocalization of TMPRSS2 with PAR2. These results point to a novel role for a cell membrane-anchored mediator in cancer pain, as well as pain in general.

  9. 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

  10. Flagella and pili-mediated near-surface single-cell motility mechanisms in P. aeruginosa.

    PubMed

    Conrad, Jacinta C; Gibiansky, Maxsim L; Jin, Fan; Gordon, Vernita D; Motto, Dominick A; Mathewson, Margie A; Stopka, Wiktor G; Zelasko, Daria C; Shrout, Joshua D; Wong, Gerard C L

    2011-04-01

    Bacterial biofilms are structured multicellular communities that are responsible for a broad range of infections. Knowing how free-swimming bacteria adapt their motility mechanisms near a surface is crucial for understanding the transition from the planktonic to the biofilm phenotype. By translating microscopy movies into searchable databases of bacterial behavior and developing image-based search engines, we were able to identify fundamental appendage-specific mechanisms for the surface motility of Pseudomonas aeruginosa. Type IV pili mediate two surface motility mechanisms: horizontally oriented crawling, by which the bacterium moves lengthwise with high directional persistence, and vertically oriented walking, by which the bacterium moves with low directional persistence and high instantaneous velocity, allowing it to rapidly explore microenvironments. The flagellum mediates two additional motility mechanisms: near-surface swimming and surface-anchored spinning, which often precedes detachment from a surface. Flagella and pili interact cooperatively in a launch sequence whereby bacteria change orientation from horizontal to vertical and then detach. Vertical orientation facilitates detachment from surfaces and thereby influences biofilm morphology. PMID:21463573

  11. 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.

  12. 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

  13. CSRP's Impact on low-income preschoolers' preacademic skills: self-regulation as a mediating mechanism.

    PubMed

    Raver, C Cybele; Jones, Stephanie M; Li-Grining, Christine; Zhai, Fuhua; Bub, Kristen; Pressler, Emily

    2011-01-01

    Based on theoretically driven models, the Chicago School Readiness Project (CSRP) targeted low-income children's school readiness through the mediating mechanism of self-regulation. The CSRP is a multicomponent, cluster-randomized efficacy trial implemented in 35 Head Start-funded classrooms (N = 602 children). The analyses confirm that the CSRP improved low-income children's self-regulation skills (as indexed by attention/impulse control and executive function) from fall to spring of the Head Start year. Analyses also suggest significant benefits of CSRP for children's preacademic skills, as measured by vocabulary, letter-naming, and math skills. Partial support was found for improvement in children's self-regulation as a hypothesized mediator for children's gains in academic readiness. Implications for programs and policies that support young children's behavioral health and academic success are discussed.

  14. Critical Role for Telomerase in the Mechanism of Flow-Mediated Dilation in the Human Microcirculation

    PubMed Central

    Freed, Julie K.; Durand, Matthew J.; Riedel, Michael; Ait-Aissa, Karima; Green, Paula; Hockenberry, Joseph C.; Morgan, R. Garret; Donato, Anthony J.; Peleg, Refael; Gasparri, Mario; Rokkas, Chris K.; Santos, Janine H.; Priel, Esther; Gutterman, David D.

    2016-01-01

    Rationale: Telomerase is a nuclear regulator of telomere elongation with recent reports suggesting a role in regulation of mitochondrial reactive oxygen species. Flow-mediated dilation in patients with cardiovascular disease is dependent on the formation of reactive oxygen species. Objective: We examined the hypothesis that telomerase activity modulates microvascular flow-mediated dilation, and loss of telomerase activity contributes to the change of mediator from nitric oxide to mitochondrial hydrogen peroxide in patients with coronary artery disease (CAD). Methods and Results: Human coronary and adipose arterioles were isolated for videomicroscopy. Flow-mediated dilation was measured in vessels pretreated with the telomerase inhibitor BIBR-1532 or vehicle. Statistical differences between groups were determined using a 2-way analysis of variance repeated measure (n≥4; P<0.05). L-NAME (Nω-nitro-L-arginine methyl ester; nitric oxide synthase inhibitor) abolished flow-mediated dilation in arterioles from subjects without CAD, whereas polyethylene glycol-catalase (PEG-catalase; hydrogen peroxide scavenger) had no effect. After exposure to BIBR-1532, arterioles from non-CAD subjects maintained the magnitude of dilation but changed the mediator from nitric oxide to mitochondrial hydrogen peroxide (% max diameter at 100 cm H2O: vehicle 74.6±4.1, L-NAME 37.0±2.0*, PEG-catalase 82.1±2.8; BIBR-1532 69.9±4.0, L-NAME 84.7±2.2, PEG-catalase 36.5±6.9*). Conversely, treatment of microvessels from CAD patients with the telomerase activator AGS 499 converted the PEG-catalase-inhibitable dilation to one mediated by nitric oxide (% max diameter at 100 cm H2O: adipose, AGS 499 78.5±3.9; L-NAME 10.9±17.5*; PEG-catalase 79.2±4.9). Endothelial-independent dilation was not altered with either treatment. Conclusions: We have identified a novel role for telomerase in re-establishing a physiological mechanism of vasodilation in arterioles from subjects with CAD. These findings

  15. Reduced expression IRF7 in nasal epithelial cells from smokers as a potential mechanism mediating enhanced susceptibility to influenza

    EPA Science Inventory

    Rationale: Smokers are more susceptible to viral infections, including influenza virus, yet the mechanisms mediating this effect are not known. Methods: We have established an in vitro model of differentiated nasal epithelial cells from smokers, which maintain enhanced levels...

  16. Two different mechanisms mediate chemotaxis to inorganic phosphate in Pseudomonas aeruginosa.

    PubMed

    Rico-Jiménez, Miriam; Reyes-Darias, Jose Antonio; Ortega, Álvaro; Díez Peña, Ana Isabel; Morel, Bertrand; Krell, Tino

    2016-06-29

    Inorganic phosphate (Pi) is a central signaling molecule that modulates virulence in various pathogens. In Pseudomonas aeruginosa, low Pi concentrations induce transcriptional alterations that increase virulence. Also, under low Pi levels, P. aeruginosa exhibits Pi chemotaxis-a process mediated by the two non-paralogous receptors CtpH and CtpL. Here we show that the two receptors operate via different mechanisms. We demonstrate that the ligand binding domain (LBD) of CtpH but not CtpL binds Pi directly. We identify the periplasmic ligand binding protein PstS as the protein that binds in its Pi loaded state to CtpL, resulting in receptor stimulation. PstS forms part of the Pi transporter and has thus a double function in Pi transport and chemotaxis. The affinity of Pi for CtpH was modest whereas that for PstS very high, which may explain why CtpH and CtpL mediate chemotaxis to high and low Pi concentrations, respectively. The pstS/ctpH double mutant was almost devoid of Pi taxis, indicating that PstS is the only CtpL Pi-shuttle. Chemotaxis mechanisms based on indirect ligand recognition were unambiguously identified in enterobacteria. The discovery of a similar mechanism in a different bacterial order, involving a different chemoreceptor type and chemoeffector suggests that such systems are widespread.

  17. P-cadherin promotes collective cell migration via a Cdc42-mediated increase in mechanical forces

    PubMed Central

    Plutoni, Cédric; Bazellieres, Elsa; Le Borgne-Rochet, Maïlys; Comunale, Franck; Brugues, Agusti; Séveno, Martial; Planchon, Damien; Thuault, Sylvie; Morin, Nathalie; Bodin, Stéphane; Trepat, Xavier

    2016-01-01

    Collective cell migration (CCM) is essential for organism development, wound healing, and metastatic transition, the primary cause of cancer-related death, and it involves cell–cell adhesion molecules of the cadherin family. Increased P-cadherin expression levels are correlated with tumor aggressiveness in carcinoma and aggressive sarcoma; however, how P-cadherin promotes tumor malignancy remains unknown. Here, using integrated cell biology and biophysical approaches, we determined that P-cadherin specifically induces polarization and CCM through an increase in the strength and anisotropy of mechanical forces. We show that this mechanical regulation is mediated by the P-cadherin/β-PIX/Cdc42 axis; P-cadherin specifically activates Cdc42 through β-PIX, which is specifically recruited at cell–cell contacts upon CCM. This mechanism of cell polarization and migration is absent in cells expressing E- or R-cadherin. Thus, we identify a specific role of P-cadherin through β-PIX–mediated Cdc42 activation in the regulation of cell polarity and force anisotropy that drives CCM. PMID:26783302

  18. Two different mechanisms mediate chemotaxis to inorganic phosphate in Pseudomonas aeruginosa

    PubMed Central

    Rico-Jiménez, Miriam; Reyes-Darias, Jose Antonio; Ortega, Álvaro; Díez Peña, Ana Isabel; Morel, Bertrand; Krell, Tino

    2016-01-01

    Inorganic phosphate (Pi) is a central signaling molecule that modulates virulence in various pathogens. In Pseudomonas aeruginosa, low Pi concentrations induce transcriptional alterations that increase virulence. Also, under low Pi levels, P. aeruginosa exhibits Pi chemotaxis—a process mediated by the two non-paralogous receptors CtpH and CtpL. Here we show that the two receptors operate via different mechanisms. We demonstrate that the ligand binding domain (LBD) of CtpH but not CtpL binds Pi directly. We identify the periplasmic ligand binding protein PstS as the protein that binds in its Pi loaded state to CtpL, resulting in receptor stimulation. PstS forms part of the Pi transporter and has thus a double function in Pi transport and chemotaxis. The affinity of Pi for CtpH was modest whereas that for PstS very high, which may explain why CtpH and CtpL mediate chemotaxis to high and low Pi concentrations, respectively. The pstS/ctpH double mutant was almost devoid of Pi taxis, indicating that PstS is the only CtpL Pi-shuttle. Chemotaxis mechanisms based on indirect ligand recognition were unambiguously identified in enterobacteria. The discovery of a similar mechanism in a different bacterial order, involving a different chemoreceptor type and chemoeffector suggests that such systems are widespread. PMID:27353565

  19. Mechanism of HSV infection through soluble adapter-mediated virus bridging to the EGF receptor

    SciTech Connect

    Nakano, Kenji; Kobayashi, Masatoshi; Nakamura, Kei-ichiro; Nakanishi, Takeshi; Asano, Ryutaro; Kumagai, Izumi; Tahara, Hideaki; Kuwano, Michihiko; Cohen, Justus B.; Glorioso, Joseph C.

    2011-04-25

    Herpes simplex virus entry into cells requires the binding of envelope glycoprotein D (gD) to an entry receptor. Depending on the cell, entry occurs by different mechanisms, including fusion at the cell surface or endocytosis. Here we examined the entry mechanism through a non-HSV receptor mediated by a soluble bi-specific adapter protein composed of recognition elements for gD and the EGF receptor (EGFR). Virus entered into endosomes using either EGF or an EGFR-specific single chain antibody (scFv) for receptor recognition. Infection was less efficient with the EGF adapter which could be attributed to its weaker binding to a viral gD. Infection mediated by the scFv adapter was pH sensitive, indicating that gD-EGFR bridging alone was insufficient for capsid release from endosomes. We also show that the scFv adapter enhanced infection of EGFR-expressing tumor tissue in vivo. Our results indicate that adapters may retarget HSV infection without drastically changing the entry mechanism.

  20. A leg-local neural mechanism mediates the decision to search in stick insects.

    PubMed

    Berg, Eva M; Hooper, Scott L; Schmidt, Joachim; Büschges, Ansgar

    2015-08-01

    In many animals, individual legs can either function independently, as in behaviors such as scratching or searching, or be used in coordinated patterns with other legs, as in walking or climbing. While the control of walking has been extensively investigated, the mechanisms mediating the behavioral choice to activate individual legs independently are poorly understood. We examined this issue in stick insects, in which each leg can independently produce a rhythmic searching motor pattern if it doesn't find a foothold [1-4]. We show here that one non-spiking interneuron, I4, controls searching behavior in individual legs. One I4 is present in each hemi-segment of the three thoracic ganglia [5, 6]. Search-inducing sensory input depolarizes I4. I4 activity was necessary and sufficient to initiate and maintain searching movements. When substrate contact was provided, I4 depolarization no longer induced searching. I4 therefore both integrates search-inducing sensory input and is gated out by other sensory input (substrate contact). Searching thus occurs only when it is behaviorally appropriate. I4 depolarization never elicited stepping. These data show that individual, locally activated neurons can mediate the behavioral choice to use individual legs independently. This mechanism may be particularly important in insects' front legs, which can function independently like vertebrate arms and hands [7]. Similar local command mechanisms that selectively activate the pattern generators controlling repeated functional units such as legs or body segments may be present in other systems.

  1. 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

  2. Functional responses and molecular mechanisms involved in histone-mediated platelet activation.

    PubMed

    Carestia, A; Rivadeneyra, L; Romaniuk, M A; Fondevila, C; Negrotto, S; Schattner, M

    2013-11-01

    Histones are highly alkaline proteins found in cell nuclei and they can be released by either dying or inflammatory cells. The recent observations that histones are major components of neutrophil extracellular traps and promote platelet aggregation and platelet-dependent thrombin generation have shown that these proteins are potent prothrombotic molecules. Because the mechanism(s) of platelet activation by histones are not completely understood, we explored the ability of individual recombinant human histones H1, H2A, H2B, H3 and H4 to induce platelet activation as well as the possible molecular mechanisms involved. All histones were substrates for platelet adhesion and spreading and triggered fibrinogen binding, aggregation, von Willebrand factor release, P-selectin and phosphatidylserine (PS) exposure and the formation of platelet-leukocyte aggregates; however, H4 was the most potent. Histone-mediated fibrinogen binding, P-selectin and PS exposure and the formation of mixed aggregates were potentiated by thrombin. Histones induced the activation of ERK, Akt, p38 and NFκB. Accordingly, histone-induced platelet activation was significantly impaired by pretreatment of platelets with inhibitors of ERK (U 0126), PI3K/Akt (Ly 294002), p38 (SB 203580) and NFκB (BAY 11-7082 and Ro 106-9920). Preincubation of platelets with either aspirin or dexamethasone markedly decreased fibrinogen binding and the adhesion mediated by histones without affecting P-selectin exposure. Functional platelet responses induced by H3 and H4, but not H1, H2A and H2B, were partially mediated through interaction with Toll-like receptors -2 and -4. Our data identify histones as important triggers of haemostatic and proinflammatory platelet responses, and only haemostatic responses are partially inhibited by anti-inflammatory drugs. PMID:23965842

  3. T-cell-mediated drug hypersensitivity: immune mechanisms and their clinical relevance.

    PubMed

    Yun, James; Cai, Fenfen; Lee, Frederick J; Pichler, Werner J

    2016-04-01

    T-cell-mediated drug hypersensitivity represents a significant proportion of immune mediated drug hypersensitivity reactions. In the recent years, there has been an increase in understanding the immune mechanisms behind T-cell-mediated drug hypersensitivity. According to hapten mechanism, drug specific T-cell response is stimulated by drug-protein conjugate presented on major histocompatibility complex (MHC) as it is presented as a new antigenic determinant. On the other hand, p-i concept suggests that a drug can stimulate T cells via noncovalent direct interaction with T-cell receptor and/or peptide-MHC. The drug binding site is quite variable and this leads to several different mechanisms within p-i concept. Altered peptide repertoire can be regarded as an 'atypical' subset of p-i concept since the mode of the drug binding and the binding site are essentially identical to p-i concept. However, the intracellular binding of abacavir to HLA-B(*)57:01 additionally results in alteration in peptide repertoire. Furthermore the T-cell response to altered peptide repertoire model is only shown for abacavir and HLA-B(*)57:01 and therefore it may not be generalised to other drug hypersensitivity. Danger hypothesis has been postulated to play an important role in drug hypersensitivity by providing signal 2 but its experimental data is lacking at this point in time. Furthermore, the recently described allo-immune response suggests that danger signal may be unnecessary. Finally, in view of these new understanding, the classification and the definition of type B adverse drug reaction should be revised. PMID:27141480

  4. T-cell-mediated drug hypersensitivity: immune mechanisms and their clinical relevance

    PubMed Central

    Cai, Fenfen; Lee, Frederick J; Pichler, Werner J

    2016-01-01

    T-cell-mediated drug hypersensitivity represents a significant proportion of immune mediated drug hypersensitivity reactions. In the recent years, there has been an increase in understanding the immune mechanisms behind T-cell-mediated drug hypersensitivity. According to hapten mechanism, drug specific T-cell response is stimulated by drug-protein conjugate presented on major histocompatibility complex (MHC) as it is presented as a new antigenic determinant. On the other hand, p-i concept suggests that a drug can stimulate T cells via noncovalent direct interaction with T-cell receptor and/or peptide-MHC. The drug binding site is quite variable and this leads to several different mechanisms within p-i concept. Altered peptide repertoire can be regarded as an 'atypical' subset of p-i concept since the mode of the drug binding and the binding site are essentially identical to p-i concept. However, the intracellular binding of abacavir to HLA-B*57:01 additionally results in alteration in peptide repertoire. Furthermore the T-cell response to altered peptide repertoire model is only shown for abacavir and HLA-B*57:01 and therefore it may not be generalised to other drug hypersensitivity. Danger hypothesis has been postulated to play an important role in drug hypersensitivity by providing signal 2 but its experimental data is lacking at this point in time. Furthermore, the recently described allo-immune response suggests that danger signal may be unnecessary. Finally, in view of these new understanding, the classification and the definition of type B adverse drug reaction should be revised. PMID:27141480

  5. Functional responses and molecular mechanisms involved in histone-mediated platelet activation.

    PubMed

    Carestia, A; Rivadeneyra, L; Romaniuk, M A; Fondevila, C; Negrotto, S; Schattner, M

    2013-11-01

    Histones are highly alkaline proteins found in cell nuclei and they can be released by either dying or inflammatory cells. The recent observations that histones are major components of neutrophil extracellular traps and promote platelet aggregation and platelet-dependent thrombin generation have shown that these proteins are potent prothrombotic molecules. Because the mechanism(s) of platelet activation by histones are not completely understood, we explored the ability of individual recombinant human histones H1, H2A, H2B, H3 and H4 to induce platelet activation as well as the possible molecular mechanisms involved. All histones were substrates for platelet adhesion and spreading and triggered fibrinogen binding, aggregation, von Willebrand factor release, P-selectin and phosphatidylserine (PS) exposure and the formation of platelet-leukocyte aggregates; however, H4 was the most potent. Histone-mediated fibrinogen binding, P-selectin and PS exposure and the formation of mixed aggregates were potentiated by thrombin. Histones induced the activation of ERK, Akt, p38 and NFκB. Accordingly, histone-induced platelet activation was significantly impaired by pretreatment of platelets with inhibitors of ERK (U 0126), PI3K/Akt (Ly 294002), p38 (SB 203580) and NFκB (BAY 11-7082 and Ro 106-9920). Preincubation of platelets with either aspirin or dexamethasone markedly decreased fibrinogen binding and the adhesion mediated by histones without affecting P-selectin exposure. Functional platelet responses induced by H3 and H4, but not H1, H2A and H2B, were partially mediated through interaction with Toll-like receptors -2 and -4. Our data identify histones as important triggers of haemostatic and proinflammatory platelet responses, and only haemostatic responses are partially inhibited by anti-inflammatory drugs.

  6. p38alpha and p38gamma mediate oncogenic ras-induced senescence through differential mechanisms.

    PubMed

    Kwong, Jinny; Hong, Lixin; Liao, Rong; Deng, Qingdong; Han, Jiahuai; Sun, Peiqing

    2009-04-24

    Oncogene-induced senescence is a tumor-suppressive defense mechanism triggered upon activation of certain oncogenes in normal cells. Recently, the senescence response to oncogene activation has been shown to act as a bona fide barrier to cancer development in vivo. Multiple previous studies have implicated the importance of the p38 MAPK pathway in oncogene-induced senescence. However, the contribution of each of the four p38 isoforms (encoded by different genes) to senescence induction is unclear. In the current study, we demonstrated that p38alpha and p38gamma, but not p38beta, play an essential role in oncogenic ras-induced senescence. Both p38alpha and p38gamma are expressed in primary human fibroblasts and are activated upon transduction of oncogenic ras. Small hairpin RNA-mediated silencing of p38alpha or p38gamma expression abrogated ras-induced senescence, whereas constitutive activation of p38alpha and p38gamma caused premature senescence. Furthermore, upon activation by oncogenic ras, p38gamma stimulated the transcriptional activity of p53 by phosphorylating p53 at Ser(33), suggesting that the ability of p38gamma to mediate senescence is at least partly achieved through p53. However, p38alpha contributed to ras-inducted senescence via a p53-indepdendent mechanism in cells by mediating ras-induced expression of p16(INK4A), another key senescence effector. These findings have identified p38alpha and p38gamma as essential components of the signaling pathway that regulates the tumor-suppressing senescence response, providing insights into the molecular mechanisms underlying the differential involvement of the p38 isoforms in senescence induction.

  7. Inhibition of mechanical allodynia in neuropathic pain by TLR5-mediated A-fiber blockade

    PubMed Central

    Xu, Zhen-Zhong; Kim, Yong Ho; Bang, Sangsu; Zhang, Yi; Berta, Temugin; Wang, Fan; Oh, Seog Bae; Ji, Ru-Rong

    2016-01-01

    SUMMARY Mechanical allodynia, induced by normally innocuous low-threshold mechanical stimulation, represents a cardinal feature of neuropathic pain. Blockade or ablation of high-threshold small-diameter unmyelinated C-fibers has limited effects on mechanical allodynia1–4. While large myelinated A-fibers, in particular Aβ-fibers, have previously been implicated in mechanical allodynia5–7, an A-fiber-selective pharmacological blocker is still lacking. Here we report a new method for targeted silencing of A-fibers in neuropathic pain. We found that Toll-like receptor 5 (TLR5) is co-expressed with neurofilament-200 in large-diameter A-fiber neurons in the dorsal root ganglion (DRG). Activation of TLR5 with its ligand flagellin results in neuronal entry of the membrane impermeable lidocaine derivative QX-314, leading to TLR5-dependent blockade of sodium currents predominantly in A-fiber neurons of mouse DRGs. Intraplantar co-application of flagellin and QX-314 (flagellin/QX-314) dose-dependently suppressed mechanical allodynia following chemotherapy, nerve injury, and diabetic neuropathy, but this blockade is abrogated in Tlr5-deficient mice. In vivo electrophysiology demonstrated that flagellin/QX-314 co-application selectively suppressed Aβ-fiber conduction in naive and chemotherapy-treated mice. TLR5-mediated Aβ blockade but not capsaicin-mediated C-fiber blockade also reduced chemotherapy-induced ongoing pain without impairing motor function. Finally, flagellin/QX-314 co-application suppressed sodium currents in large-diameter human DRG neurons. Thus, our findings provide a new tool for targeted silencing of Aβ-fibers and neuropathic pain treatment. PMID:26479925

  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. Molecular mechanisms involving sigma receptor-mediated induction of MCP-1: implication for increased monocyte transmigration.

    PubMed

    Yao, Honghong; Yang, Yanjing; Kim, Kee Jun; Bethel-Brown, Crystal; Gong, Nan; Funa, Keiko; Gendelman, Howard E; Su, Tsung-Ping; Wang, John Q; Buch, Shilpa

    2010-06-10

    Cocaine abuse hastens the neurodegeneration often associated with advanced HIV-1 infection. The mechanisms, in part, revolve around the neuroinflammatory processes mediated by the chemokine monocyte chemotactic protein-1 (MCP-1/CCL2). Understanding factors that modulate MCP-1 and, in turn, facilitate monocyte extravasation in the brain is thus of paramount importance. We now demonstrate that cocaine induces MCP-1 in rodent microglia through translocation of the sigma receptor to the lipid raft microdomains of the plasma membrane. Sequential activation of Src, mitogen-activated protein kinases (MAPKs), and phosphatidylinositol-3' kinase (PI3K)/Akt and nuclear factor kappaB (NF-kappaB) pathways resulted in increased MCP-1 expression. Furthermore, conditioned media from cocaine-exposed microglia increased monocyte transmigration, and thus was blocked by antagonists for CCR2 or sigma receptor. These findings were corroborated by demonstrating increased monocyte transmigration in mice exposed to cocaine, which was attenuated by pretreatment of mice with the sigma receptor antagonist. Interestingly, cocaine-mediated transmigratory effects were not observed in CCR2 knockout mice. We conclude that cocaine-mediated induction of MCP-1 accelerates monocyte extravasation across the endothelium. Understanding the regulation of MCP-1 expression and functional changes by cocaine/sigma receptor system may provide insights into the development of potential therapeutic targets for HIV-1-associated neurocognitive disorders. PMID:20354174

  10. Calmodulin dissociation mediates desensitization of the cADPR-induced Ca2+ release mechanism.

    PubMed

    Thomas, Justyn M; Summerhill, Robin J; Fruen, Bradley R; Churchill, Grant C; Galione, Antony

    2002-12-10

    Ryanodine receptor (RyR) activation by cyclic ADP-ribose (cADPR) is followed by homologous desensitization. Though poorly understood, this "switching off" process has provided a key experimental tool for determining the pathway through which cADPR mediates Ca(2+) release. Moreover, desensitization is likely to play an important role in shaping the complexities of Ca(2+) signaling involving cADPR, for example, localized release events and propagated waves. Using the sea urchin egg, we unmask a role of calmodulin, a component of the RyR complex and a key cofactor for cADPR activity, during RyR/cADPR desensitization. Recovery from desensitization in calmodulin-depleted purified endoplasmic reticulum (microsomes) is severely impaired compared to that in crude egg homogenates. An active, soluble factor, identified as calmodulin, is required to restore the capacity of microsomes to recover from desensitization. Calmodulin mediates recovery in a manner that tightly parallels its time course of association with the RyR. Conversely, direct measurement of calmodulin binding to microsomes reveals a loss of specific binding during cADPR, but not IP(3), desensitization. Our results support a mechanism in which cycles of calmodulin dissociation and reassociation to an endoplasmic reticulum protein, most likely the RyR itself, mediate RyR/cADPR desensitization and resensitization, respectively. PMID:12477390

  11. Histopathologic insights into the mechanism of anti-non-Gal antibody-mediated pig cardiac xenograft rejection

    PubMed Central

    Byrne, Guerard W; Azimzadeh, Agnes M; Ezzelarab, Mohamed; Tazelaar, Henry D; Ekser, Burcin; Pierson, Richard N; Robson, Simon C; Cooper, David K C; McGregor, Christopher G A

    2013-01-01

    The histopathology of cardiac xenograft rejection has evolved over the last 20 yr with the development of new modalities for limiting antibody-mediated injury, advancing regimens for immune suppression, and an ever-widening variety of new donor genetics. These new technologies have helped us progress from what was once an overwhelming anti-Gal-mediated hyperacute rejection to a more protracted anti-Gal-mediated vascular rejection to what is now a more complex manifestation of non-Gal humoral rejection and coagulation dysregulation. This review summarizes the changing histopathology of Gal- and non-Gal-mediated cardiac xenograft rejection and discusses the contributions of immune-mediated injury, species-specific immune-independent factors, transplant and therapeutic procedures, and donor genetics to the overall mechanism(s) of cardiac xenograft rejection. PMID:25098626

  12. Social, institutional, and knowledge mechanisms mediate diverse ecosystem service benefits from coral reefs.

    PubMed

    Hicks, Christina C; Cinner, Joshua E

    2014-12-16

    Ecosystem services are supplied by nature but, by definition, are received by people. Ecosystem service assessments, intended to influence the decisions people make regarding their interactions with nature, need to understand how people benefit from different ecosystem services. A critical question is therefore, What determines the distribution of ecosystem service benefits between different sections of society? Here, we use an entitlements approach to examine how people perceive ecosystem service benefits across 28 coral reef fishing communities in four countries. In doing so, we quantitatively show that bundles of benefits are mediated by key access mechanisms (e.g., rights-based, economic, knowledge, social, and institutional). We find that specific access mechanisms influence which ecosystem services people prioritize. Social, institutional, and knowledge mechanisms are associated with the largest number and diversity of benefits. However, local context strongly determines whether specific access mechanisms enable or constrain benefits. Local ecological knowledge enabled people to prioritize a habitat benefit in Kenya, but constrained people from prioritizing the same benefit in Madagascar. Ecosystem service assessments, and their resultant policies, need to include the broad suite of access mechanisms that enable different people to benefit from a supply of ecosystem services. PMID:25453100

  13. DNA sequence-dependent mechanics and protein-assisted bending in repressor-mediated loop formation

    PubMed Central

    Boedicker, James Q.; Garcia, Hernan G.; Johnson, Stephanie; Phillips, Rob

    2014-01-01

    As the chief informational molecule of life, DNA is subject to extensive physical manipulations. The energy required to deform double-helical DNA depends on sequence, and this mechanical code of DNA influences gene regulation, such as through nucleosome positioning. Here we examine the sequence-dependent flexibility of DNA in bacterial transcription factor-mediated looping, a context for which the role of sequence remains poorly understood. Using a suite of synthetic constructs repressed by the Lac repressor and two well-known sequences that show large flexibility differences in vitro, we make precise statistical mechanical predictions as to how DNA sequence influences loop formation and test these predictions using in vivo transcription and in vitro single-molecule assays. Surprisingly, sequence-dependent flexibility does not affect in vivo gene regulation. By theoretically and experimentally quantifying the relative contributions of sequence and the DNA-bending protein HU to DNA mechanical properties, we reveal that bending by HU dominates DNA mechanics and masks intrinsic sequence-dependent flexibility. Such a quantitative understanding of how mechanical regulatory information is encoded in the genome will be a key step towards a predictive understanding of gene regulation at single-base pair resolution. PMID:24231252

  14. Social, institutional, and knowledge mechanisms mediate diverse ecosystem service benefits from coral reefs.

    PubMed

    Hicks, Christina C; Cinner, Joshua E

    2014-12-16

    Ecosystem services are supplied by nature but, by definition, are received by people. Ecosystem service assessments, intended to influence the decisions people make regarding their interactions with nature, need to understand how people benefit from different ecosystem services. A critical question is therefore, What determines the distribution of ecosystem service benefits between different sections of society? Here, we use an entitlements approach to examine how people perceive ecosystem service benefits across 28 coral reef fishing communities in four countries. In doing so, we quantitatively show that bundles of benefits are mediated by key access mechanisms (e.g., rights-based, economic, knowledge, social, and institutional). We find that specific access mechanisms influence which ecosystem services people prioritize. Social, institutional, and knowledge mechanisms are associated with the largest number and diversity of benefits. However, local context strongly determines whether specific access mechanisms enable or constrain benefits. Local ecological knowledge enabled people to prioritize a habitat benefit in Kenya, but constrained people from prioritizing the same benefit in Madagascar. Ecosystem service assessments, and their resultant policies, need to include the broad suite of access mechanisms that enable different people to benefit from a supply of ecosystem services.

  15. [Mechanisms underlying interferon-mediated host innate immunity during influenza A virus infection].

    PubMed

    Chen, Chao; Chi, Xiaojuan; Bai, Qingling; Chen, Jilong

    2015-12-01

    Influenza A virus can create acute respiratory infection in humans and animals throughout the world, and it is still one of the major causes of morbidity and mortality in humans worldwide. Numerous studies have shown that influenza A virus infection induces rapidly host innate immune response. Influenza A virus triggers the activation of signaling pathways that are dependent on host pattern recognition receptors (PRRs) including toll like receptors (TLRs) and RIG-I like receptors (RLRs). Using a variety of regulatory mechanisms, these signaling pathways activate downstream transcript factors that control expression of various interferons and cytokines, such as type I and type III interferons. Thus, these interferons stimulate the transcript of relevant interferon-stimulated genes (ISGs) and expression of the antiviral proteins, which are critical components of host innate immunity. In this review, we will highlight the mechanisms by which influenza A virus infection induces the interferon-mediated host innate immunity.

  16. Oxidative Stress-Mediated Skeletal Muscle Degeneration: Molecules, Mechanisms, and Therapies

    PubMed Central

    Choi, Min Hee; Ow, Jin Rong; Yang, Nai-Di

    2016-01-01

    Oxidative stress is a loss of balance between the production of reactive oxygen species during cellular metabolism and the mechanisms that clear these species to maintain cellular redox homeostasis. Increased oxidative stress has been associated with muscular dystrophy, and many studies have proposed mechanisms that bridge these two pathological conditions at the molecular level. In this review, the evidence indicating a causal role of oxidative stress in the pathogenesis of various muscular dystrophies is revisited. In particular, the mediation of cellular redox status in dystrophic muscle by NF-κB pathway, autophagy, telomere shortening, and epigenetic regulation are discussed. Lastly, the current stance of targeting these pathways using antioxidant therapies in preclinical and clinical trials is examined. PMID:26798425

  17. Simvastatin may induce insulin resistance through a novel fatty acid mediated cholesterol independent mechanism

    PubMed Central

    Kain, Vasundhara; Kapadia, Bandish; Misra, Parimal; Saxena, Uday

    2015-01-01

    Statins are a class of oral drugs that are widely used for treatment of hypercholesterolemia. Recent clinical data suggest that chronic use of these drugs increases the frequency of new onset diabetes. Studies to define the risks of statin-induced diabetes and its underlying mechanisms are clearly necessary. We explored the possible mechanism of statin induced insulin resistance using a well-established cell based model and simvastatin as a prototype statin. Our data show that simvastatin induces insulin resistance in a cholesterol biosynthesis inhibition independent fashion but does so by a fatty acid mediated effect on insulin signaling pathway. These data may help design strategies for prevention of statin induced insulin resistance and diabetes in patients with hypercholesterolemia. PMID:26345110

  18. An electrostatic mechanism for Ca(2+)-mediated regulation of gap junction channels.

    PubMed

    Bennett, Brad C; Purdy, Michael D; Baker, Kent A; Acharya, Chayan; McIntire, William E; Stevens, Raymond C; Zhang, Qinghai; Harris, Andrew L; Abagyan, Ruben; Yeager, Mark

    2016-01-01

    Gap junction channels mediate intercellular signalling that is crucial in tissue development, homeostasis and pathologic states such as cardiac arrhythmias, cancer and trauma. To explore the mechanism by which Ca(2+) blocks intercellular communication during tissue injury, we determined the X-ray crystal structures of the human Cx26 gap junction channel with and without bound Ca(2+). The two structures were nearly identical, ruling out both a large-scale structural change and a local steric constriction of the pore. Ca(2+) coordination sites reside at the interfaces between adjacent subunits, near the entrance to the extracellular gap, where local, side chain conformational rearrangements enable Ca(2+)chelation. Computational analysis revealed that Ca(2+)-binding generates a positive electrostatic barrier that substantially inhibits permeation of cations such as K(+) into the pore. Our results provide structural evidence for a unique mechanism of channel regulation: ionic conduction block via an electrostatic barrier rather than steric occlusion of the channel pore. PMID:26753910

  19. Mechanisms of complement-mediated clearance of bacteria from the murine lung.

    PubMed

    Heidbrink, P J; Toews, G B; Gross, G N; Pierce, A K

    1982-05-01

    Complement factors enhance host defense against bacterial challenges by attracting phagocytic cells to the site of the inoculum and by opsonizing bacteria for phagocytic ingestion. The relative contribution of these 2 mechanisms to in vivo clearance of bacteria from the lung has not been described. Hypocomplementemic and normal animals were challenged with various bacteria. Clearance of bacteria was studied by quantitative lung culture. Phagocytic response was determined by bronchoalveolar lavage. Staphylococci were cleared by macrophages without regard to the complement status of the host. Hypocomplementemic animals cleared pneumococci less efficiently than did control animals. This defect correlated with decreased neutrophil recruitment. Pseudomonas was not cleared in hypocomplementemic animals, but there was no difference in the number or type of phagocytes. This implies that an opsonic rather thn a chemotactic defect was responsible. These data suggest that the mechanism of complement-mediated defense against bacterial challenge varies with the type of pathogen present.

  20. Defect-mediated polarization switching in ferroelectrics and related materials: from mesoscopic mechanisms to atomistic control.

    PubMed

    Kalinin, Sergei V; Rodriguez, Brian J; Borisevich, Albina Y; Baddorf, Arthur P; Balke, Nina; Chang, Hye Jung; Chen, Long-Qing; Choudhury, Samrat; Jesse, Stephen; Maksymovych, Peter; Nikiforov, Maxim P; Pennycook, Stephen J

    2010-01-19

    The plethora of lattice and electronic behaviors in ferroelectric and multiferroic materials and heterostructures opens vistas into novel physical phenomena including magnetoelectric coupling and ferroelectric tunneling. The development of new classes of electronic, energy-storage, and information-technology devices depends critically on understanding and controlling field-induced polarization switching. Polarization reversal is controlled by defects that determine activation energy, critical switching bias, and the selection between thermodynamically equivalent polarization states in multiaxial ferroelectrics. Understanding and controlling defect functionality in ferroelectric materials is as critical to the future of oxide electronics and solid-state electrochemistry as defects in semiconductors are for semiconductor electronics. Here, recent advances in understanding the defect-mediated switching mechanisms, enabled by recent advances in electron and scanning probe microscopy, are discussed. The synergy between local probes and structural methods offers a pathway to decipher deterministic polarization switching mechanisms on the level of a single atomically defined defect.

  1. The transport and mediation mechanisms of the common sugars in Escherichia coli.

    PubMed

    Luo, Yane; Zhang, Tao; Wu, Hui

    2014-01-01

    Escherichia coli can uptake and utilize many common natural sugars to form biomass or valuable target bio-products. Carbon catabolite repression (CCR) will occur and hamper the efficient production of bio-products if E. coli strains are cultivated in a mixture of sugars containing some preferred sugar, such as glucose. Understanding the transport and metabolism mechanisms of the common and inexpensive sugars in E. coli is important for further improving the efficiency of sugar bioconversion and for reducing industrial fermentation costs using the methods of metabolic engineering, synthetic biology and systems biology. In this review, the transport and mediation mechanisms of glucose, fructose, sucrose, xylose and arabinose are discussed and summarized, and the hierarchical utilization principles of these sugars are elucidated.

  2. An electrostatic mechanism for Ca2+-mediated regulation of gap junction channels

    PubMed Central

    Bennett, Brad C.; Purdy, Michael D.; Baker, Kent A.; Acharya, Chayan; McIntire, William E.; Stevens, Raymond C.; Zhang, Qinghai; Harris, Andrew L.; Abagyan, Ruben; Yeager, Mark

    2016-01-01

    Gap junction channels mediate intercellular signalling that is crucial in tissue development, homeostasis and pathologic states such as cardiac arrhythmias, cancer and trauma. To explore the mechanism by which Ca2+ blocks intercellular communication during tissue injury, we determined the X-ray crystal structures of the human Cx26 gap junction channel with and without bound Ca2+. The two structures were nearly identical, ruling out both a large-scale structural change and a local steric constriction of the pore. Ca2+ coordination sites reside at the interfaces between adjacent subunits, near the entrance to the extracellular gap, where local, side chain conformational rearrangements enable Ca2+chelation. Computational analysis revealed that Ca2+-binding generates a positive electrostatic barrier that substantially inhibits permeation of cations such as K+ into the pore. Our results provide structural evidence for a unique mechanism of channel regulation: ionic conduction block via an electrostatic barrier rather than steric occlusion of the channel pore. PMID:26753910

  3. Molecular Mechanisms Responsible for Neuron-Derived Conditioned Medium (NCM)-Mediated Protection of Ischemic Brain

    PubMed Central

    Lin, Chi-Hsin; Wang, Chen-Hsuan; Hsu, Shih-Lan; Liao, Li-Ya; Lin, Ting-An; Hsueh, Chi-Mei

    2016-01-01

    The protective value of neuron-derived conditioned medium (NCM) in cerebral ischemia and the underlying mechanism(s) responsible for NCM-mediated brain protection against cerebral ischemia were investigated in the study. NCM was first collected from the neuronal culture growing under the in vitro ischemic condition (glucose-, oxygen- and serum-deprivation or GOSD) for 2, 4 or 6 h. Through the focal cerebral ischemia (bilateral CCAO/unilateral MCAO) animal model, we discovered that ischemia/reperfusion (I/R)-induced brain infarction was significantly reduced by NCM, given directly into the cistern magna at the end of 90 min of CCAO/MCAO. Immunoblocking and chemical blocking strategies were applied in the in vitro ischemic studies to show that NCM supplement could protect microglia, astrocytes and neurons from GOSD-induced cell death, in a growth factor (TGFβ1, NT-3 and GDNF) and p-ERK dependent manner. Brain injection with TGFβ1, NT3, GDNF and ERK agonist (DADS) alone or in combination, therefore also significantly decreased the infarct volume of ischemic brain. Moreover, NCM could inhibit ROS but stimulate IL-1β release from GOSD-treated microglia and limit the infiltration of IL-β-positive microglia into the core area of ischemic brain, revealing the anti-oxidant and anti-inflammatory activities of NCM. In overall, NCM-mediated brain protection against cerebral ischemia has been demonstrated for the first time in S.D. rats, due to its anti-apoptotic, anti-oxidant and potentially anti-glutamate activities (NCM-induced IL-1β can inhibit the glutamate-mediated neurotoxicity) and restriction upon the infiltration of inflammatory microglia into the core area of ischemic brain. The therapeutic potentials of NCM, TGFβ1, GDNF, NT-3 and DADS in the control of cerebral ischemia in human therefore have been suggested and require further investigation. PMID:26745377

  4. Molecular Mechanisms Responsible for Neuron-Derived Conditioned Medium (NCM)-Mediated Protection of Ischemic Brain.

    PubMed

    Lin, Chi-Hsin; Wang, Chen-Hsuan; Hsu, Shih-Lan; Liao, Li-Ya; Lin, Ting-An; Hsueh, Chi-Mei

    2016-01-01

    The protective value of neuron-derived conditioned medium (NCM) in cerebral ischemia and the underlying mechanism(s) responsible for NCM-mediated brain protection against cerebral ischemia were investigated in the study. NCM was first collected from the neuronal culture growing under the in vitro ischemic condition (glucose-, oxygen- and serum-deprivation or GOSD) for 2, 4 or 6 h. Through the focal cerebral ischemia (bilateral CCAO/unilateral MCAO) animal model, we discovered that ischemia/reperfusion (I/R)-induced brain infarction was significantly reduced by NCM, given directly into the cistern magna at the end of 90 min of CCAO/MCAO. Immunoblocking and chemical blocking strategies were applied in the in vitro ischemic studies to show that NCM supplement could protect microglia, astrocytes and neurons from GOSD-induced cell death, in a growth factor (TGFβ1, NT-3 and GDNF) and p-ERK dependent manner. Brain injection with TGFβ1, NT3, GDNF and ERK agonist (DADS) alone or in combination, therefore also significantly decreased the infarct volume of ischemic brain. Moreover, NCM could inhibit ROS but stimulate IL-1β release from GOSD-treated microglia and limit the infiltration of IL-β-positive microglia into the core area of ischemic brain, revealing the anti-oxidant and anti-inflammatory activities of NCM. In overall, NCM-mediated brain protection against cerebral ischemia has been demonstrated for the first time in S.D. rats, due to its anti-apoptotic, anti-oxidant and potentially anti-glutamate activities (NCM-induced IL-1β can inhibit the glutamate-mediated neurotoxicity) and restriction upon the infiltration of inflammatory microglia into the core area of ischemic brain. The therapeutic potentials of NCM, TGFβ1, GDNF, NT-3 and DADS in the control of cerebral ischemia in human therefore have been suggested and require further investigation. PMID:26745377

  5. Ultrasound Microbubble Treatment Enhances Clathrin-Mediated Endocytosis and Fluid-Phase Uptake through Distinct Mechanisms.

    PubMed

    Fekri, Farnaz; Delos Santos, Ralph Christian; Karshafian, Raffi; Antonescu, Costin N

    2016-01-01

    Drug delivery to tumors is limited by several factors, including drug permeability of the target cell plasma membrane. Ultrasound in combination with microbubbles (USMB) is a promising strategy to overcome these limitations. USMB treatment elicits enhanced cellular uptake of materials such as drugs, in part as a result of sheer stress and formation of transient membrane pores. Pores formed upon USMB treatment are rapidly resealed, suggesting that other processes such as enhanced endocytosis may contribute to the enhanced material uptake by cells upon USMB treatment. How USMB regulates endocytic processes remains incompletely understood. Cells constitutively utilize several distinct mechanisms of endocytosis, including clathrin-mediated endocytosis (CME) for the internalization of receptor-bound macromolecules such as Transferrin Receptor (TfR), and distinct mechanism(s) that mediate the majority of fluid-phase endocytosis. Tracking the abundance of TfR on the cell surface and the internalization of its ligand transferrin revealed that USMB acutely enhances the rate of CME. Total internal reflection fluorescence microscopy experiments revealed that USMB treatment altered the assembly of clathrin-coated pits, the basic structural units of CME. In addition, the rate of fluid-phase endocytosis was enhanced, but with delayed onset upon USMB treatment relative to the enhancement of CME, suggesting that the two processes are distinctly regulated by USMB. Indeed, vacuolin-1 or desipramine treatment prevented the enhancement of CME but not of fluid phase endocytosis upon USMB, suggesting that lysosome exocytosis and acid sphingomyelinase, respectively, are required for the regulation of CME but not fluid phase endocytosis upon USMB treatment. These results indicate that USMB enhances both CME and fluid phase endocytosis through distinct signaling mechanisms, and suggest that strategies for potentiating the enhancement of endocytosis upon USMB treatment may improve targeted

  6. Aquaporin-1 Translocation and Degradation Mediates the Water Transportation Mechanism of Acetazolamide

    PubMed Central

    Gao, Junwei; Han, Jing; Pan, Xueyang; Pan, Yan; Tie, Lu; Li, Xuejun

    2012-01-01

    Background Diuretic agents are widely used on the treatment of water retention related diseases, among which acetazolamide (AZA) acts originally as a carbonic anhydrase (CA) inhibitor. Aquaporin-1 (AQP1) being located in renal proximal tubules is required for urine concentration. Previously our lab has reported AZA putatively modulated AQP1. Aim of this study is to testify our hypothesis that regulating AQP1 may mediate diuretic effect of AZA. Methodology/Principal Findings For in vivo study, we utilized Sprague Dawley rats, as well as AQP1 knock-out (AQP1−/−) mice to examine urine volume, and human kidney-2 (HK-2) cell line was used for in vitro mechanism study. In our present study we found that AZA decreased CAs activity initially but the activity gradually recovered. Contrarily, diuretic effect was consistently significant. AQP1 protein expression was significantly decreased on day 7 and 14. By utilizing AQP1−/− mice, we found diuretic effect of AZA was cancelled on day 14, while urine volume continuously increased in wild-type mice. Surface plasmon resonance (SPR) results indicated AQP1 was physiologically bound by myosin heavy chain (MHC), immunoprecipitation and immunofluorescence results confirmed this protein interaction. In vitro study results proved AZA facilitated AQP1 translocation onto cell membrane by promoting interaction with MHC, dependent on ERK/ myosin light chain kinase (MLCK) pathway activation. MHC inhibitor BDM and ERK inhibitor U0126 both abolished above effect of AZA. Eventually AZA induced AQP1 ubiquitination, while proteasome inhibitor MG132 reversed AZA's down-regulating effect upon AQP1. Conclusions/Significance Our results identified AZA exerted diuretic effect through an innovative mechanism by regulating AQP1 and verified its inhibitory mechanism was via promoting MHC-dependent translocation onto cell membrane and then ubiquitin mediated degradation, implicating a novel mechanism and target for diuretic agent discovering

  7. Central mechanisms mediating the hypophagic effects of oleoylethanolamide and N-acylphosphatidylethanolamines: different lipid signals?

    PubMed Central

    Romano, Adele; Tempesta, Bianca; Provensi, Gustavo; Passani, Maria B.; Gaetani, Silvana

    2015-01-01

    The spread of “obesity epidemic” and the poor efficacy of many anti-obesity therapies in the long-term highlight the need to develop novel efficacious therapy. This necessity stimulates a large research effort to find novel mechanisms controlling feeding and energy balance. Among these mechanisms a great deal of attention has been attracted by a family of phospholipid-derived signaling molecules that play an important role in the regulation of food-intake. They include N-acylethanolamines (NAEs) and N-acylphosphatidylethanolamines (NAPEs). NAPEs have been considered for a long time simply as phospholipid precursors of the lipid mediator NAEs, but increasing body of evidence suggest a role in many physiological processes including the regulation of feeding behavior. Several observations demonstrated that among NAEs, oleoylethanolamide (OEA) acts as a satiety signal, which is generated in the intestine, upon the ingestion of fat, and signals to the central nervous system. At this level different neuronal pathways, including oxytocinergic, noradrenergic, and histaminergic neurons, seem to mediate its hypophagic action. Similarly to NAEs, NAPE (with particular reference to the N16:0 species) levels were shown to be regulated by the fed state and this finding was initially interpreted as fluctuations of NAE precursors. However, the observation that exogenously administered NAPEs are able to inhibit food intake, not only in normal rats and mice but also in mice lacking the enzyme that converts NAPEs into NAEs, supported the hypothesis of a role of NAPE in the regulation of feeding behavior. Indirect observations suggest that the hypophagic action of NAPEs might involve central mechanisms, although the molecular target remains unknown. The present paper reviews the role that OEA and NAPEs play in the mechanisms that control food intake, further supporting this group of phospholipids as optimal candidate for the development of novel anti-obesity treatments. PMID

  8. Ultrasound Microbubble Treatment Enhances Clathrin-Mediated Endocytosis and Fluid-Phase Uptake through Distinct Mechanisms

    PubMed Central

    Fekri, Farnaz; Delos Santos, Ralph Christian; Karshafian, Raffi

    2016-01-01

    Drug delivery to tumors is limited by several factors, including drug permeability of the target cell plasma membrane. Ultrasound in combination with microbubbles (USMB) is a promising strategy to overcome these limitations. USMB treatment elicits enhanced cellular uptake of materials such as drugs, in part as a result of sheer stress and formation of transient membrane pores. Pores formed upon USMB treatment are rapidly resealed, suggesting that other processes such as enhanced endocytosis may contribute to the enhanced material uptake by cells upon USMB treatment. How USMB regulates endocytic processes remains incompletely understood. Cells constitutively utilize several distinct mechanisms of endocytosis, including clathrin-mediated endocytosis (CME) for the internalization of receptor-bound macromolecules such as Transferrin Receptor (TfR), and distinct mechanism(s) that mediate the majority of fluid-phase endocytosis. Tracking the abundance of TfR on the cell surface and the internalization of its ligand transferrin revealed that USMB acutely enhances the rate of CME. Total internal reflection fluorescence microscopy experiments revealed that USMB treatment altered the assembly of clathrin-coated pits, the basic structural units of CME. In addition, the rate of fluid-phase endocytosis was enhanced, but with delayed onset upon USMB treatment relative to the enhancement of CME, suggesting that the two processes are distinctly regulated by USMB. Indeed, vacuolin-1 or desipramine treatment prevented the enhancement of CME but not of fluid phase endocytosis upon USMB, suggesting that lysosome exocytosis and acid sphingomyelinase, respectively, are required for the regulation of CME but not fluid phase endocytosis upon USMB treatment. These results indicate that USMB enhances both CME and fluid phase endocytosis through distinct signaling mechanisms, and suggest that strategies for potentiating the enhancement of endocytosis upon USMB treatment may improve targeted

  9. Evidence for water-mediated mechanisms in coral-algal interactions.

    PubMed

    Jorissen, Hendrikje; Skinner, Christina; Osinga, Ronald; de Beer, Dirk; Nugues, Maggy M

    2016-08-17

    Although many coral reefs have shifted from coral-to-algal dominance, the consequence of such a transition for coral-algal interactions and their underlying mechanisms remain poorly understood. At the microscale, it is unclear how diffusive boundary layers (DBLs) and surface oxygen concentrations at the coral-algal interface vary with algal competitors and competitiveness. Using field observations and microsensor measurements in a flow chamber, we show that coral (massive Porites) interfaces with thick turf algae, macroalgae, and cyanobacteria, which are successful competitors against coral in the field, are characterized by a thick DBL and hypoxia at night. In contrast, coral interfaces with crustose coralline algae, conspecifics, and thin turf algae, which are poorer competitors, have a thin DBL and low hypoxia at night. Furthermore, DBL thickness and hypoxia at the interface with turf decreased with increasing flow speed, but not when thick turf was upstream. Our results support the importance of water-mediated transport mechanisms in coral-algal interactions. Shifts towards algal dominance, particularly dense assemblages, may lead to thicker DBLs, higher hypoxia, and higher concentrations of harmful metabolites and pathogens along coral borders, which in turn may facilitate algal overgrowth of live corals. These effects may be mediated by flow speed and orientation. PMID:27512146

  10. Hepatocyte-mediated cytotoxicity and host defense mechanisms in the alcohol-injured liver.

    PubMed

    McVicker, Benita L; Thiele, Geoffrey M; Tuma, Dean J; Casey, Carol A

    2014-09-01

    The consumption of alcohol is associated with many health issues including alcoholic liver disease (ALD). The natural history of ALD involves the development of steatosis, inflammation (steatohepatitis), fibrosis and cirrhosis. During the stage of steatohepatitis, the combination of inflammation and cellular damage can progress to a severe condition termed alcoholic hepatitis (AH). Unfortunately, the pathogenesis of AH remains uncharacterized. Some modulations have been identified in host defense and liver immunity mechanisms during AH that highlight the role of intrahepatic lymphocyte accumulation and associated inflammatory cytokine responses. Also, it is hypothesized that alcohol-induced injury to liver cells may significantly contribute to the aberrant lymphocytic distribution that is seen in AH. In particular, the regulation of lymphocytes by hepatocytes may be disrupted in the alcoholic liver resulting in altered immunologic homeostasis and perpetuation of disease. In recent studies, it was demonstrated that the direct killing of activated T lymphocytes by hepatocytes is facilitated by the asialoglycoprotein receptor (ASGPR). The ASGPR is a well-characterized glycoprotein receptor that is exclusively expressed by hepatocytes. This hepatic receptor is known for its role in the clearance of desialylated glycoproteins or cells, yet neither its physiological function nor its role in disease states has been determined. Interestingly, alcohol markedly impairs ASGPR function; however, the effect alcohol has on ASGPR-mediated cytotoxicity of lymphocytes remains to be elucidated. This review discusses the contribution of hepatocytes in immunological regulation and, importantly, how pathological effects of ethanol disrupt hepatocellular-mediated defense mechanisms.

  11. Direct and quinone-mediated palladium reduction by Geobacter sulfurreducens: mechanisms and modeling.

    PubMed

    Pat-Espadas, Aurora M; Razo-Flores, Elías; Rangel-Mendez, J Rene; Cervantes, Francisco J

    2014-01-01

    Palladium(II) reduction to Pd(0) nanoparticles by Geobacter sulfurreducens was explored under conditions of neutral pH, 30 °C and concentrations of 25, 50, and 100 mg of Pd(II)/L aiming to investigate the effect of solid species of palladium on their microbial reduction. The influence of anthraquinone-2,6-disulfonate was reported to enhance the palladium reaction rate in an average of 1.7-fold and its addition is determining to achieve the reduction of solid species of palladium. Based on the obtained results two mechanisms are proposed: (1) direct, which is fully described considering interactions of amide, sulfur, and phosphoryl groups associated to proteins from bacteria on palladium reduction reaction, and (2) quinone-mediated, which implies multiheme c-type cytochromes participation. Speciation analysis and kinetic results were considered and integrated into a model to fit the experimental data that explain both mechanisms. This work provides elements for a better understanding of direct and quinone-mediated palladium reduction by G. sulfurreducens, which could facilitate metal recovery with concomitant formation of valuable palladium nanoparticles in industrial processes.

  12. Pili-mediated Interactions between Neisseria Gonorrhoeae Bacteria are the Driving Mechanism of Microcolony Merging

    NASA Astrophysics Data System (ADS)

    Poenisch, Wolfram; Weber, Christoph; Alzurqa, Khaled; Nasrollahi, Hadi; Biais, Nicolas; Zaburdaev, Vasily; Collective Dynamics of Cells Team; Mechano-Micro-Biology Lab Team

    2015-03-01

    During the early infection with Neisseria gonorrhoeae the bacteria form microcolonies consisting of a few hundreds to a few thousands of cells. The formation of colonies is mediated by type IV pili, thin and long filaments that are also involved in the motion of single cells over a substrate. A related process causes attractive cell-cell-interactions. While the motion of single cells has been extensively studied during the past years, the physical principles driving the growth of these colonies are poorly understood. One key mechanism of colony growth is coalescence of smaller colonies. Therefore we experimentally examine the process of merging of two Neisseria gonorrhoeae colonies. We develop a theoretical microscopic model of single cells interacting solely by their pili. The experimental data and the results obtained from our model are in excellent quantitative agreement. We observe a fast initial approach of the two merging colonies within a few minutes, that is followed by a slow relaxation of the colony shape with a characteristic time of several hours. These findings suggest that pili-mediated interactions are the primary driving mechanism of the microcolony merging process.

  13. 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

  14. 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

  15. 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

  16. 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

  17. Gq-mediated Akt translocation to the membrane: a novel PIP3-independent mechanism in platelets.

    PubMed

    Badolia, Rachit; Manne, Bhanu Kanth; Dangelmaier, Carol; Chernoff, Jonathan; Kunapuli, Satya P

    2015-01-01

    Akt is an important signaling molecule regulating platelet aggregation. Akt is phosphorylated after translocation to the membrane through Gi signaling pathways by a phosphatidylinositol-3,4,5-trisphosphate (PIP3)-dependent mechanism. However, Akt is more robustly phosphorylated by thrombin compared with adenosine 5'-diphosphate in platelets. This study investigated the mechanisms of Akt translocation as a possible explanation for this difference. Stimulation of washed human platelets with protease-activated receptor agonists caused translocation of Akt to the membrane rapidly, whereas phosphorylation occurred later. The translocation of Akt was abolished in the presence of a Gq-selective inhibitor or in Gq-deficient murine platelets, indicating that Akt translocation is regulated downstream of Gq pathways. Interestingly, phosphatidylinositol 3-kinase (PI3K) inhibitors or P2Y12 antagonist abolished Akt phosphorylation without affecting Akt translocation to the membrane, suggesting that Akt translocation occurs through a PI3K/PIP3/Gi-independent mechanism. An Akt scaffolding protein, p21-activated kinase (PAK), translocates to the membrane after stimulation with protease-activated receptor agonists in a Gq-dependent manner, with the kinetics of translocation similar to that of Akt. Coimmunoprecipitation studies showed constitutive association of PAK and Akt, suggesting a possible role of PAK in Akt translocation. These results show, for the first time, an important role of the Gq pathway in mediating Akt translocation to the membrane in a novel Gi/PI3K/PIP3-independent mechanism.

  18. Gq-mediated Akt translocation to the membrane: a novel PIP3-independent mechanism in platelets

    PubMed Central

    Badolia, Rachit; Manne, Bhanu Kanth; Dangelmaier, Carol; Chernoff, Jonathan

    2015-01-01

    Akt is an important signaling molecule regulating platelet aggregation. Akt is phosphorylated after translocation to the membrane through Gi signaling pathways by a phosphatidylinositol-3,4,5-trisphosphate (PIP3)-dependent mechanism. However, Akt is more robustly phosphorylated by thrombin compared with adenosine 5′-diphosphate in platelets. This study investigated the mechanisms of Akt translocation as a possible explanation for this difference. Stimulation of washed human platelets with protease-activated receptor agonists caused translocation of Akt to the membrane rapidly, whereas phosphorylation occurred later. The translocation of Akt was abolished in the presence of a Gq-selective inhibitor or in Gq-deficient murine platelets, indicating that Akt translocation is regulated downstream of Gq pathways. Interestingly, phosphatidylinositol 3-kinase (PI3K) inhibitors or P2Y12 antagonist abolished Akt phosphorylation without affecting Akt translocation to the membrane, suggesting that Akt translocation occurs through a PI3K/PIP3/Gi-independent mechanism. An Akt scaffolding protein, p21-activated kinase (PAK), translocates to the membrane after stimulation with protease-activated receptor agonists in a Gq-dependent manner, with the kinetics of translocation similar to that of Akt. Coimmunoprecipitation studies showed constitutive association of PAK and Akt, suggesting a possible role of PAK in Akt translocation. These results show, for the first time, an important role of the Gq pathway in mediating Akt translocation to the membrane in a novel Gi/PI3K/PIP3-independent mechanism. PMID:25331114

  19. Distinguishing BIS-mediated and BAS-mediated disinhibition mechanisms: a comparison of disinhibition models of Gray (1981, 1987) and of Patterson and Newman (1993).

    PubMed

    Avila, C

    2001-02-01

    The theoretical framework developed by J. A. Gray (1981, 1987a, 1987b) was used to study disinhibitory behavior. Using a point-scoring reaction time procedure, 4 different experiments were conducted to differentiate 2 disinhibitory mechanisms associated with the behavioral activation system (BAS) and the behavioral inhibition system (BIS). Consistent with the work of C. M. Patterson and J. P. Newman (1993), the BAS-mediated mechanism was related to a lack of inhibition in reward-directed behavior after introducing an occasional aversive contingency and to deficits in learning from aversive cues when responding for reward (Experiments 1-3). The BIS-mediated mechanism was related to a higher ability to extinguish aversive associations (Experiment 1), a lower aversive generalization gradient (Experiment 3), and a lower interference with appetitive behavior in the presence of aversive stimuli (Experiment 4).

  20. Mechanisms of islet damage mediated by pancreas cold ischemia/rewarming.

    PubMed

    Omori, Keiko; Kobayashi, Eiji; Rawson, Jeffrey; Takahashi, Masafumi; Mullen, Yoko

    2016-10-01

    Prolonged pancreas cold ischemia is known to negatively correlate with islet isolation outcomes, hindering successful islet transplantation to treat Type-1 Diabetes. Due to poor islet isolation outcome, pancreata with over 16 h cold ischemia are currently not considered for islet transplantation. Mechanisms involved in pancreas cold ischemia/rewarming mediated islet damage during islet isolation and culture are not well understood. Using an en bloc cold preserved rat pancreas preparation, we attempted to clarify possible mechanisms of islet death associated with prolonged pancreas cold ischemia and subsequent rewarming. Cold ischemia lasting 16 h decreased post-isolation islet yield and increased islet death during the initial 6 h of culture. Electron micrographs revealed swelling and severe disruption of cellular and mitochondrial membranes, as well as an enlarged endoplasmic reticulum (ER) in β-cells isolated from cold preserved pancreata. Prolonged cold ischemia of the pancreas transiently activated mitogen-activated protein kinases (MAPKs) in isolated islets and increased lipid peroxidation products 4-hydroxynonenal (HNE) and heat shock protein (Hsp) 70 after culture, indicating the activation of oxidative stress signaling pathways. The islet isolation process, irrespective of pancreas cold ischemia, activated unfolded protein response (UPR), while the ER protective chaperon BiP was further upregulated by pancreas cold ischemia/rewarming. During the first 6 h of culture following islet isolation, p53 upregulated modulator of apoptosis (Puma) and caspase-3 activation were also upregulated. Our study indicates the involvement of both apoptosis and necrosis in islet death, and suggests oxidative stress and disruption of membranes are critical mechanisms mediated by pancreas cold ischemia/rewarming. PMID:27587006

  1. Magnesium ions and opioid agonist activity in streptozotocin-induced hyperalgesia.

    PubMed

    Bujalska, Magdalena; Malinowska, Ewelina; Makulska-Nowak, Helena; Gumułka, Stanisław Witold

    2008-01-01

    Streptozotocin-induced hyperglycemia accompanied by a chronic decrease in the nociceptive threshold is considered a useful model of experimental hyperalgesia. We examined (1) the effect of the opioid receptor agonists and (2) the effect of the magnesium ions (Mg(2+)) on the antinociceptive action of opioid agonists in a diabetic neuropathic pain model. When administered alone, opioid agonists like morphine (5 mg/kg i.p.) and fentanyl (0.0625 mg/kg i.p.), as well as the partial agonist buprenorphine (0.075 mg/kg) had only little effect on streptozotocin-induced hyperalgesia. However, pretreatment with Mg(2+) at a dose of 40 mg magnesium sulfate/kg i.p. markedly enhanced the analgesic activity of all three investigated opioids. Practical aspects of co-administration of magnesium and opioids in diabetic neuropathy are discussed. PMID:18701828

  2. Failure of intrathecal ketorolac to reduce remifentanil-induced postinfusion hyperalgesia in humans.

    PubMed

    Eisenach, James C; Tong, Chuanyao; Curry, Regina S

    2015-01-01

    In rodents, acute exposure to opioids results in transient antinociception followed by longer lasting hypersensitivity to tactile or thermal stimuli, a phenomenon termed opioid-induced hyperalgesia. This hypersensitivity can be blocked or reversed by intrathecally administered cyclooxygenase inhibitors, including ketorolac, suggesting a role for spinal prostaglandins. In surgical patients, the dose of intraoperative opioid, particularly the short-acting drug, remifentanil, is directly related to increased pain and opioid requirements for many hours postoperatively. In addition, experimentally induced tactile hypersensitivity in humans is exaggerated after cessation of remifentanil infusions. The degree of this experimental opioid-induced hyperalgesia is reduced by systemic treatment with cyclooxygenase inhibitors, and investigators have speculated that this reduction reflects the actions in the central nervous system, most likely in the spinal cord. To test this hypothesis, we measured cerebrospinal fluid prostaglandin E2 concentrations during and after remifentanil infusion in 30 volunteers. These volunteers received intrathecal ketorolac or saline in a random, blinded manner during intravenous remifentanil infusion after generation of hypersensitivity by topical capsaicin. Remifentanil reduced pain to noxious heat stimuli and reduced areas of capsaicin-induced hypersensitivity similarly in those receiving intrathecal ketorolac or saline. The primary outcome measure, area of capsaicin-induced hypersensitivity after stopping remifentanil, showed a similar increase in those receiving ketorolac as in those receiving saline. Cerebrospinal fluid prostaglandin E2 concentrations did not increase during postinfusion hyperalgesia compared with those during infusion, and they were not increased during infusion compared with those in historical controls. These data fail to support the hypothesis that acute opioid-induced hyperalgesia reflects spinal cyclooxygenase activation

  3. Calpain-Mediated Tau Cleavage: A Mechanism Leading to Neurodegeneration Shared by Multiple Tauopathies

    PubMed Central

    Ferreira, Adriana; Bigio, Eileen H

    2011-01-01

    Tau dysfunction has been associated with a host of neurodegenerative diseases called tauopathies. These diseases share, as a common pathological hallmark, the presence of intracellular aggregates of hyperphosphorylated tau in affected brain areas. Aside from tau hyperphosphorylation, little is known about the role of other posttranslational modifications in tauopathies. Recently, we obtained data suggesting that calpain-mediated tau cleavage leading to the generation of a neurotoxic tau fragment might play an important role in Alzheimer’s disease. In the current study, we assessed the presence of this tau fragment in several tauopathies. Our results show high levels of the 17-kDa tau fragment and enhanced calpain activity in the temporal cortex of AD patients and in brain samples obtained from patients with other tauopathies. In addition, our data suggest that this fragment could partially inhibit tau aggregation. Conversely, tau aggregation might prevent calpain-mediated cleavage, establishing a feedback circuit that might lead to the accumulation of this toxic tau fragment. Collectively, these data suggest that the mechanism underlying the generation of the 17-kDa neurotoxic tau fragment might be part of a conserved pathologic process shared by multiple tauopathies. PMID:21442128

  4. Free radical-mediated oxidative DNA damage in the mechanism of thalidomide teratogenicity.

    PubMed

    Parman, T; Wiley, M J; Wells, P G

    1999-05-01

    The sedative drug thalidomide ([+]-alpha-phthalimidoglutarimide), once abandoned for causing birth defects in humans, has found new therapeutic license in leprosy and other diseases, with renewed teratological consequences. Although the mechanism of teratogenesis and determinants of risk remain unclear, related teratogenic xenobiotics are bioactivated by embryonic prostaglandin H synthase (PHS) to a free-radical intermediates that produce reactive oxygen species (ROS), which cause oxidative damage to DNA and other cellular macromolecules. Similarly, thalidomide is bioactivated by horseradish peroxidase, and oxidizes DNA and glutathione, indicating free radical-mediated oxidative stress. Furthermore, thalidomide teratogenicity in rabbits is reduced by the PHS inhibitor acetylsalicylic acid, indicating PHS-catalyzed bioactivation. Here, we show in rabbits that thalidomide initiates embryonic DNA oxidation and teratogenicity, both of which are abolished by pre-treatment with the free radical spin trapping agent alpha-phenyl-N-t-butylnitrone (PBN). In contrast, in mice, a species resistant to thalidomide teratogenicity, thalidomide does not enhance DNA oxidation, even at a dose 300% higher than that used in rabbits, providing insight into an embryonic determinant of species-dependent susceptibility. In addition to their therapeutic implications, these results constitute direct evidence that the teratogenicity of thalidomide may involve free radical-mediated oxidative damage to embryonic cellular macromolecules.

  5. Molecular mechanism of SCARB2-mediated attachment and uncoating of EV71.

    PubMed

    Dang, Minghao; Wang, Xiangxi; Wang, Quan; Wang, Yaxin; Lin, Jianping; Sun, Yuna; Li, Xuemei; Zhang, Liguo; Lou, Zhiyong; Wang, Junzhi; Rao, Zihe

    2014-09-01

    Unlike the well-established picture for the entry of enveloped viruses, the mechanism of cellular entry of non-enveloped eukaryotic viruses remains largely mysterious. Picornaviruses are representative models for such viruses, and initiate this entry process by their functional receptors. Here we present the structural and functional studies of SCARB2, a functional receptor of the important human enterovirus 71 (EV71). SCARB2 is responsible for attachment as well as uncoating of EV71. Differences in the structures of SCARB2 under neutral and acidic conditions reveal that SCARB2 undergoes a pivotal pH-dependent conformational change which opens a lipid-transfer tunnel to mediate the expulsion of a hydrophobic pocket factor from the virion, a pre-requisite for uncoating. We have also identified the key residues essential for attachment to SCARB2, identifying the canyon region of EV71 as mediating the receptor interaction. Together these results provide a clear understanding of cellular attachment and initiation of uncoating for enteroviruses.

  6. Lithium diisopropylamide-mediated ortholithiation of 2-fluoropyridines: rates, mechanisms, and the role of autocatalysis.

    PubMed

    Gupta, Lekha; Hoepker, Alexander C; Ma, Yun; Viciu, Mihai S; Faggin, Marc F; Collum, David B

    2013-05-01

    Lithium diisopropylamide (LDA)-mediated ortholithiations of 2-fluoropyridine and 2,6-difluoropyridine in tetrahydrofuran at -78 °C were studied using a combination of IR and NMR spectroscopic and computational methods. Rate studies show that a substrate-assisted deaggregation of LDA dimer occurs parallel to an unprecedented tetramer-based pathway. Standard and competitive isotope effects confirm post-rate-limiting proton transfer. Autocatalysis stems from ArLi-catalyzed deaggregation of LDA proceeding via 2:2 LDA-ArLi mixed tetramers. A hypersensitivity of the ortholithiation rates to traces of LiCl derives from LiCl-catalyzed LDA dimer-monomer exchange and a subsequent monomer-based ortholithiation. Fleeting 2:2 LDA-LiCl mixed tetramers are suggested to be key intermediates. The mechanisms of both the uncatalyzed and catalyzed deaggregations are discussed. A general mechanistic paradigm is delineated to explain a number of seemingly disparate LDA-mediated reactions, all of which occur in tetrahydrofuran at -78 °C.

  7. Candida mannan: chemistry, suppression of cell-mediated immunity, and possible mechanisms of action.

    PubMed Central

    Nelson, R D; Shibata, N; Podzorski, R P; Herron, M J

    1991-01-01

    The ability of Candida albicans to establish an infection involves multiple components of this fungal pathogen, but its ability to persist in host tissue may involve primarily the immunosuppressive property of a major cell wall glycoprotein, mannan. Mannan and oligosaccharide fragments of mannan are potent inhibitors of cell-mediated immunity and appear to reproduce the immune deficit of patients with the mucocutaneous form of candidiasis. However, neither the exact structures of these inhibitory species nor their mechanisms of action have yet been clearly defined. Different investigators have proposed that mannan or mannan catabolites act upon monocytes or suppressor T lymphocytes, but research from unrelated areas has provided still other possibilities for consideration. These include interference with cytokine activities, lymphocyte-monocyte interactions, and leukocyte homing. To stimulate further research of the immunosuppressive property of C. albicans mannan, we have reviewed (i) the relationship of mannan to other antigens and virulence factors of the fungus; (ii) the chemistry of mannan, together with methods for preparation of mannan and mannan fragments; and (iii) the historical evidence for immunosuppression by Candida mannan and the mechanisms currently proposed for this property; and (iv) we have speculated upon still other mechanisms by which mannan might influence host defense functions. It is possible that understanding the immunosuppressive effects of mannan will provide clues to novel therapies for candidiasis that will enhance the efficacy of both available and future anti-Candida agents. PMID:2004345

  8. The cGMP/PKG pathway as a common mediator of cardioprotection: translatability and mechanism

    PubMed Central

    Inserte, Javier; Garcia-Dorado, David

    2015-01-01

    Cardiomyocyte cell death occurring during myocardial reperfusion (reperfusion injury) contributes to final infarct size after transient coronary occlusion. Different interrelated mechanisms of reperfusion injury have been identified, including alterations in cytosolic Ca2+ handling, sarcoplasmic reticulum-mediated Ca2+ oscillations and hypercontracture, proteolysis secondary to calpain activation and mitochondrial permeability transition. All these mechanisms occur during the initial minutes of reperfusion and are inhibited by intracellular acidosis. The cGMP/PKG pathway modulates the rate of recovery of intracellular pH, but has also direct effect on Ca2+ oscillations and mitochondrial permeability transition. The cGMP/PKG pathway is depressed in cardiomyocytes by ischaemia/reperfusion and preserved by ischaemic postconditioning, which importantly contributes to postconditioning protection. The present article reviews the mechanisms and consequences of the effect of ischaemic postconditioning on the cGMP/PKG pathway, the different pharmacological strategies aimed to stimulate it during myocardial reperfusion and the evidence, limitations and promise of translation of these strategies to the clinical practice. Overall, the preclinical and clinical evidence suggests that modulation of the cGMP/PKG pathway may be a therapeutic target in the context of myocardial infarction. PMID:25297462

  9. From Nanowires to Biofilms: An Exploration of Novel Mechanisms of Uranium Transformation Mediated by Geobacter Bacteria

    SciTech Connect

    REGUERA, GEMMA

    2014-01-16

    One promising strategy for the in situ bioremediation of radioactive groundwater contaminants that has been identified by the SBR Program is to stimulate the activity of dissimilatory metal-reducing microorganisms to reductively precipitate uranium and other soluble toxic metals. The reduction of U(VI) and other soluble contaminants by Geobacteraceae is directly dependent on the reduction of Fe(III) oxides, their natural electron acceptor, a process that requires the expression of Geobacter’s conductive pili (pilus nanowires). Expression of conductive pili by Geobacter cells leads to biofilm development on surfaces and to the formation of suspended biogranules, which may be physiological closer to biofilms than to planktonic cells. Biofilm development is often assumed in the subsurface, particularly at the matrix-well screen interface, but evidence of biofilms in the bulk aquifer matrix is scarce. Our preliminary results suggest, however, that biofilms develop in the subsurface and contribute to uranium transformations via sorption and reductive mechanisms. In this project we elucidated the mechanism(s) for uranium immobilization mediated by Geobacter biofilms and identified molecular markers to investigate if biofilm development is happening in the contaminated subsurface. The results provided novel insights needed in order to understand the metabolic potential and physiology of microorganisms with a known role in contaminant transformation in situ, thus having a significant positive impact in the SBR Program and providing novel concept to monitor, model, and predict biological behavior during in situ treatments.

  10. Antibody-mediated disruption of the mechanics of CS20 fimbriae of enterotoxigenic Escherichia coli

    PubMed Central

    Singh, Bhupender; Mortezaei, Narges; Uhlin, Bernt Eric; Savarino, Stephen J.; Bullitt, Esther; Andersson, Magnus

    2015-01-01

    Preventive vaccines against enterotoxigenic Escherichia coli (ETEC) are being developed, many of which target common fimbrial colonization factors as the major constituent, based on empirical evidence that these function as protective antigens. Particularly, passive oral administration of ETEC anti-fimbrial antibodies prevent ETEC diarrhea. Little is, however, known regarding the specific mechanisms by which intestinal antibodies against ETEC fimbriae function to prevent disease. Using coli surface antigen 20 (CS20) fimbriae as a model ETEC colonization factor, we show using force spectroscopy that anti-fimbrial antibodies diminish fimbrial elasticity by inhibiting their natural capacity to unwind and rewind. In the presence of anti-CS20 antibodies the force required to unwind a single fimbria was increased several-fold and the extension length was shortened several-fold. Similar measurements in the presence of anti-CS20 Fab fragments did not show any effect, indicating that bivalent antibody binding is required to reduce fimbrial elasticity. Based on these findings, we propose a model for an in-vivo mechanism whereby antibody-mediated disruption of the biomechanical properties of CS20 fimbriae impedes sustained adhesion of ETEC to the intestinal mucosal surface. Further elucidation of the role played by intestinal antibodies in mechanical disruption of fimbrial function may provide insights relevant to ETEC vaccine development. PMID:26411657

  11. Antibody-mediated disruption of the mechanics of CS20 fimbriae of enterotoxigenic Escherichia coli.

    PubMed

    Singh, Bhupender; Mortezaei, Narges; Uhlin, Bernt Eric; Savarino, Stephen J; Bullitt, Esther; Andersson, Magnus

    2015-01-01

    Preventive vaccines against enterotoxigenic Escherichia coli (ETEC) are being developed, many of which target common fimbrial colonization factors as the major constituent, based on empirical evidence that these function as protective antigens. Particularly, passive oral administration of ETEC anti-fimbrial antibodies prevent ETEC diarrhea. Little is, however, known regarding the specific mechanisms by which intestinal antibodies against ETEC fimbriae function to prevent disease. Using coli surface antigen 20 (CS20) fimbriae as a model ETEC colonization factor, we show using force spectroscopy that anti-fimbrial antibodies diminish fimbrial elasticity by inhibiting their natural capacity to unwind and rewind. In the presence of anti-CS20 antibodies the force required to unwind a single fimbria was increased several-fold and the extension length was shortened several-fold. Similar measurements in the presence of anti-CS20 Fab fragments did not show any effect, indicating that bivalent antibody binding is required to reduce fimbrial elasticity. Based on these findings, we propose a model for an in-vivo mechanism whereby antibody-mediated disruption of the biomechanical properties of CS20 fimbriae impedes sustained adhesion of ETEC to the intestinal mucosal surface. Further elucidation of the role played by intestinal antibodies in mechanical disruption of fimbrial function may provide insights relevant to ETEC vaccine development. PMID:26411657

  12. Pulsed high intensity focused ultrasound mediated nanoparticle delivery: Mechanisms and efficacy in murine muscle

    PubMed Central

    O’Neill, Brian E.; Vo, Howard; Angstadt, Mary; Li, King P. C.; Quinn, Tim; Frenkel, Victor

    2009-01-01

    High intensity focused ultrasound (HIFU) is generally thought to interact with biological tissues in two ways: hyperthermia (heat) and acoustic cavitation. Pulsed mode HIFU has recently been demonstrated to increase the efficacy of a variety of drug therapies. Generally, it is presumed that the treatment acts to temporarily increase the permeability of the tissue to the therapeutic agent, however, the precise mechanism remains in dispute. In this paper, we present evidence precluding hyperthermia as a principal mechanism for enhancing delivery, using a quantitative analysis of systemically administered fluorescent nanoparticles delivered to muscle in the flanks of mice. Comparisons were carried out on the degree of enhancement between an equivalent heat treatment, delivered without ultrasound, and that of the pulsed-HIFU itself. In the murine calf muscle, pulsed-HIFU treatment resulted in a significant increase in distribution of 200 nm particles (p<0.016, N=6), while the equivalent thermal dose showed no significant increase. Additional studies using this tissue/agent model also demonstrated that the pulsed HIFU enhancing effects persist for more than 24 hours, which is longer than that of hyperthermia and acoustic cavitation, and offers the possibility of a novel third mechanism for mediating delivery. PMID:19081668

  13. Pharmacological treatment of opioid-induced hyperalgesia: a review of the evidence.

    PubMed

    Ramasubbu, Chitra; Gupta, Anita

    2011-01-01

    Opioids are commonly used to treat moderate to severe pain. Opioid-induced hyperalgesia is a paradoxical response to opioid agonists resulting in an increased perception of pain rather than an antinociceptive effect. Even though there is a debate regarding its clinical relevance, it is becoming a challenge in both acute and chronic pain settings. The study of opioid-induced hyperalgesia is an emerging field with multiple challenges faced by investigators with regard to defining the diagnosis and characterizing the findings. The objective of this study was to review the preliminary evidence related to the treatment and management of opioid-induced hyperalgesia. Lack of data, small patient numbers, short-term follow-up, and variations in study design limited the review. With the literature on this subject being sparse, this study attempts to provide a preliminary look at the available data and to set the stage for an eventual meta-analysis. Case reports in the literature have shown success with various pharmacological interventions. Possible treatment regimens include ketamine, dextromethorphan, and nonsteroidal anti-inflammatory drugs (NSAIDs), opioid switching, amantadine, buprenorphine, α(2) agonists, and methadone. These agents are briefly discussed in this paper. Further well-designed, placebo-controlled trials are needed to assess the effectiveness of the interventions investigated in this review.

  14. Effects of hydroxytyrosol-20 on carrageenan-induced acute inflammation and hyperalgesia in rats.

    PubMed

    Gong, Dezheng; Geng, Chengyan; Jiang, Liping; Cao, Jun; Yoshimura, Hiroyuki; Zhong, Laifu

    2009-05-01

    Hydroxytyrosol (HT) is a simple phenol compound extracted from olive leaves. The content of HT in the studied preparation was about 20%, and the preparation was called hydroxytyrosol-20 (HT-20). HT has antioxidant and antiinflammatory activities. There has been no report so far on the efficacy of HT-20 in carrageenan-induced acute inflammation and hyperalgesia in rats. Therefore, the aim of this study was to assess the inhibitory role of HT-20 on carrageenan-induced swelling and hyperalgesia of rat paw. Paw inflammation was assessed by the increase in paw volume and hyperalgesia. The rat paws were cut out under ether anesthesia at 270 min after administration of carrageenan. The tissue of the right paw was isolated separately from the individual rat. The levels of the tumor necrosis factor-alpha (TNF-alpha), interleukin 1beta (IL-1beta) and interleukin 10 (IL-10) mRNA in the tissue were estimated by reverse transcription-polymerase chain reaction (RT-PCR). The results showed that the paw pressure thresholds of rats orally administered HT-20 significantly increased at 210, 240 and 270 min after administration of carrageenan, compared with corresponding basal paw pressure thresholds; the degree of swelling of the right hind paw showed a statistically significant reduction, compared with rats in the carrageenan-treated control. In this model, HT-20 appears to decrease pro-inflammatory cytokines IL-1beta and TNF-alpha and not to increase the antiinflammatory cytokine mRNA expression of IL-10.

  15. Involvement of peripheral TRPV1 in TMJ hyperalgesia induced by ethanol withdrawal.

    PubMed

    Urtado, Marília Bertoldo; Gameiro, Gustavo Hauber; Tambeli, Cláudia Herrera; Fischer, Luana; Urtado, Christiano Bertoldo; de Arruda Veiga, Maria Cecília Ferraz

    2007-11-30

    Ethanol withdrawal increases nociception after the injection of formalin into the rat's temporomandibular joint (TMJ). Little is known about the neurological basis for hyperalgesia induced by ethanol withdrawal, but it has been reported that ethanol can potentiate the response of transient receptor potential vanilloid receptor-1 (TRPV1) in superficial tissues. The present study was designed to test the hypothesis that peripheral TRPV1 could be involved on nociceptive behavioral responses induced by the injection of formalin into the TMJ region of rats exposed to chronic ethanol administration and ethanol withdrawal. Behavioral hyperalgesia was verified 12 h after ethanol withdrawal in rats that drank an ethanol solution (6.5%) for 10 days. In another group submitted to the same ethanol regimen, the selective vanilloid receptor antagonist capsazepine (300, 600 or 1200 microg/25 microl) or an equal volume of vehicle were injected into the TMJ regions 30 min before the TMJ formalin test. The local injections of capsazepine reduced the increased nociceptive responses induced by ethanol withdrawal. The effect of capsazepine on rats that did not drink ethanol was not significant. These results indicate that the peripheral TRPV1 can contribute to the hyperalgesia induced by ethanol withdrawal on deep pain conditions.

  16. Concerted and asynchronous mechanism of ground state proton transfer in alcohol mediated 7-hydroxyquinoline

    NASA Astrophysics Data System (ADS)

    Kang, Baotao; Jang, Du-Jeon; Lee, Jin Yong

    2015-07-01

    Alcohols mediated 7-hydroxyquinoline (7-HQ) complex has received enormous attractions on the issue of proton transfer reaction in the ground and excited states. In the present paper, concentrating on the ground state proton transfer (GSPT), density functional theory (DFT) calculations were carried out to investigate the intrinsic insight into the reaction mechanism. We found that the GSPT is concerted and asynchronous process and can be accelerated by more acidic alcohol. Such GSPT was initiated by the proton transfer from alcohol to keto group of 7-HQ and finished by the proton transfer from nitrogen to alcohol. Our findings were in agreement with experimental conclusions quite well. Our results would be helpful to understand the proton transfer reaction for 7-HQ and related systems.

  17. Cognitive neuroscience of cognitive retraining for addiction medicine: From mediating mechanisms to questions of efficacy.

    PubMed

    Gladwin, Thomas E; Wiers, Corinde E; Wiers, Reinout W

    2016-01-01

    Cognitive retraining or cognitive bias modification (CBM) involves having subjects repeatedly perform a computerized task designed to reduce the impact of automatic processes that lead to harmful behavior. We first discuss the theory underlying CBM and provide a brief overview of important research progress in its application to addiction. We then focus on cognitive- and neural-mediating mechanisms. We consider recent criticism of both CBM and its theoretical foundations. Evaluations of CBM could benefit from considering theory-driven factors that may determine variations in efficacy, such as motivation. Concerning theory, while there is certainly room for fundamental advances in current models, we argue that the basic view of impulsive behavior and its control remains a useful and productive heuristic. Finally, we briefly discuss some interesting new directions for CBM research: enhancement of training via transcranial direct current stimulation, online training, and gamification, i.e., the use of gameplay elements to increase motivation. PMID:26822365

  18. Hormone-Mediated Intercellular Calcium Signalling in an Insect Salivary Gland Pathways and Mechanisms

    NASA Astrophysics Data System (ADS)

    Zimmermann, Bernhard; Walz, Bernd

    The salivary glands of the blowfly Calliphora vicina are a favourable preparation for investigations into spatio-temporal Ca 2+ dynamics in an intact miniorgan by using Ca 2+-sensitive indicator dyes and digital imaging techniques, including confocal microscopy, in combination with pharmacological approaches. The review summarizes the available data on the spatio-temporal patterns of the hormone-induced and IP 3-mediated Ca 2+ dynamics at both the intracellular and the intercellular level (intra- and intercellular Ca 2+ waves). The underlying signaling mechanisms are addressed, as well as the pathways of intercellular communication responsible for the complex spatio-temporal Ca 2+ dynamics. In addition, we review evidence for the exchange of Ca 2+ between IP 3 sensitive intracellular Ca 2+ stores and mitochondria including a modulatory effect of mitochondrial Ca 2+ uptake on the frequency of IP 3-induced Ca 2+ spiking.

  19. Siderophore-mediated iron acquisition mechanisms in Vibrio vulnificus biotype 2.

    PubMed Central

    Biosca, E G; Fouz, B; Alcaide, E; Amaro, C

    1996-01-01

    Vibrio vulnificus biotype 2 is a primary pathogen for eels and, as has recently been suggested, an opportunistic pathogen for humans. In this study we have investigated the ability of V. vulnificus biotype 2 to obtain iron by siderophore-mediated mechanisms and evaluated the importance of free iron in vibriosis. The virulence degree for eels was dependent on iron availability from host fluids, as was revealed by a reduction in the 50% lethal dose for iron-overloaded eels. This biotype produced both phenolate- and hydroxamate-type siderophores of an unknown nature and two new outer membrane proteins of around 84 and 72 kDa in response to iron starvation. No alterations in lipopolysaccharide patterns were detected in response to iron stress. Finally, our data suggest that V. vulnificus biotype 2 uses the hydroxamate-type siderophore for removal of iron from transferrin rather than relying on a receptor for this iron-binding protein. PMID:8975620

  20. Tryptophan depletion as a mechanism of gamma interferon-mediated chlamydial persistence.

    PubMed Central

    Beatty, W L; Belanger, T A; Desai, A A; Morrison, R P; Byrne, G I

    1994-01-01

    Previous studies have shown that the immune-regulated cytokine gamma interferon (IFN-gamma) activates host cells to restrict intracellular growth of the bacterial pathogen Chlamydia trachomatis by induction of the tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO). Recently, subinhibitory levels of IFN-gamma were used to generate an in vitro persistent chlamydial infection characterized by large aberrant, noninfectious reticulate bodies from which infectious progeny could be recovered following the removal of IFN-gamma. Studies were done to determine if the mechanism functioning to induce chlamydiae to enter a persistent state in the presence of low levels of IFN-gamma was similar to that reported to inhibit chlamydial growth. Host cells treated with levels of IFN-gamma required to induce persistence were assessed for IDO activity by high-performance liquid chromatography analysis of tryptophan and its catabolic products. Substantial tryptophan catabolism was detected in acid-soluble cellular pools, indicating that the intracellular availability of this essential amino acid was limited under these conditions. In addition, a mutant cell line responsive to IFN-gamma but deficient in IDO activity was shown to support C. trachomatis growth, but aberrant organisms were not induced in response to IFN-gamma treatment. Analyses of infected cells cultured in medium with incremental levels of exogenous tryptophan indicated that persistent growth was induced by reducing the amount of this essential amino acid. These studies confirmed that nutrient deprivation by IDO-mediated tryptophan catabolism was the mechanism by which IFN-gamma mediates persistent growth of C. trachomatis. Images PMID:8063385

  1. Extracellular ATP mediates Ca2+ signaling in cultured myenteric neurons via a PLC-dependent mechanism.

    PubMed

    Kimball, B C; Yule, D I; Mulholland, M W

    1996-04-01

    In the myenteric plexus, ATP is released as a neurotransmitter by "purinergic" nerves, relaxing visceral smooth muscle. We report a signal transduction mechanism for ATP in cultured myenteric neurons involving receptor-mediated release of intracellular Ca2+ stores. Primary cultures of myenteric neurons from guinea pigs taenia coli were loaded with the Ca2+ indicator fura 2-acetoxymethyl ester (AM) and examined using digital imaging microscopy. Superfusion of single neurons with ATP (0.01-1,000 microM) resulted in concentration-dependent increases in intracellular Ca2+ concentration ([Ca2+]i) that were independent of extracellular Ca2+. Decrements in peak [Ca2+]i were seen with repetitive ATP exposure. Responsiveness of myenteric neurons to purinergic agonists (100 microM) was consistent with action at a neuronal P 2y purinoceptor: 2-chloro-ATP = ATP = 2-methyl-thio-ATP (MeSATP) > ADP > alpha, beta-MeATP = beta,gamma-MeATP > AMP > adenosine. ATP-evoked Ca2+ transients were inhibited dose dependently by suramin, a nonspecific P2 antagonist, and reactive blue 2, a specific P 2y antagonist. ATP and cyclopiazonic acid (30 microM) appear to release an identical intracellular Ca2+ store. Preincubation with the aminosteroid U-73122 (10 microM) inhibited ATP-evoked Ca2+ transients by 71 +/- 7%, whereas phorbol ester pretreatment (phorbol 12-myristate 13-acetate, 100 nM, 5 min) caused a 76 +/- 4% inhibition. Peak [Ca2+]i evoked by ATP was not affected by preincubation with pertussis toxin (100 ng/ml, 24 h) or nifedipine (10 microM). These data suggest a signal transduction mechanism for ATP in cultured myenteric neurons involving purinoceptor-mediated activation of phospholipase C (PLC), with release of D-myo-inositol 1,4,5-trisphosphate-sensitive intracellular Ca2+ stores.

  2. Mechanisms mediating enhanced neutralization efficacy of staphylococcal enterotoxin B by combinations of monoclonal antibodies.

    PubMed

    Dutta, Kaushik; Varshney, Avanish K; Franklin, Matthew C; Goger, Michael; Wang, Xiaobo; Fries, Bettina C

    2015-03-13

    Staphylococcal enterotoxin B (SEB) is a superantigen that cross-links the major histocompatibility complex class II and specific V-β chains of the T-cell receptor, thus forming a ternary complex. Developing neutralizing mAb to disrupt the ternary complex and abrogate the resulting toxicity is a major therapeutic challenge because SEB is effective at very low concentrations. We show that combining two SEB-specific mAbs enhances their efficacy, even though one of the two mAbs by itself has no effect on neutralization. Crystallography was employed for fine-mapping conformational epitopes in binary and ternary complexes between SEB and Fab fragments. NMR spectroscopy was used to validate and identify subtle allosteric changes induced by mAbs binding to SEB. The mapping of epitopes established that a combination of different mAbs can enhance efficacy of mAb-mediated protection from SEB induced lethal shock by two different mechanisms: one mAb mixture promoted clearance of the toxin both in vitro and in vivo by FcR-mediated cross-linking and clearance, whereas the other mAb mixture induced subtle allosteric conformational changes in SEB that perturbed formation of the SEB·T-cell receptor·major histocompatibility complex class II trimer. Finally structural information accurately predicted mAb binding to other superantigens that share conformational epitopes with SEB. Fine mapping of conformational epitopes is a powerful tool to establish the mechanism and optimize the action of synergistic mAb combinations. PMID:25572397

  3. Receptor-mediated mechanism for the transport of prolactin from blood to cerebrospinal fluid

    SciTech Connect

    Walsh, R.J.; Slaby, F.J.; Posner, B.I.

    1987-05-01

    Prolactin (PRL) interacts with areas of the central nervous system which reside behind the blood-brain barrier. While vascular PRL does not cross this barrier, it is readily accessible to the cerebrospinal fluid (CSF) from which it may gain access to the PRL-responsive areas of the brain. Studies were undertaken to characterize the mechanism responsible for the translocation of PRL from blood to CSF. Rats were given external jugular vein injections of (/sup 125/-I)iodo-PRL in the presence or absence of an excess of unlabeled ovine PRL (oPRL), human GH, bovine GH, or porcine insulin. CSF and choroid plexus were removed 60 min later. CSF samples were electrophoresed on sodium dodecyl sulfate-polyacrylamide slab gels and resultant autoradiographs were analyzed with quantitative microdensitometry. The data revealed that unlabeled lactogenic hormones, viz. oPRL and human GH, caused a statistically significant inhibition of (/sup 125/I)iodo-PRL transport from blood to CSF. In contrast, nonlactogenic hormones, viz bovine GH and insulin, had no effect on (/sup 125/I)iodo-PRL transport into the CSF. An identical pattern of competition was observed in the binding of hormone to the choroid plexus. Furthermore, vascular injections of (/sup 125/I)iodo-PRL administered with a range of concentrations of unlabeled oPRL revealed a dose-response inhibition in the transport of (/sup 125/I)iodo-PRL from blood to CSF. The study demonstrates that PRL enters the CSF by a specific, PRL receptor-mediated transport mechanism. The data is consistent with the hypothesis that the transport mechanism resides at the choroid plexus. The existence of this transport mechanism reflects the importance of the cerebroventricular system in PRL-brain interactions.

  4. Ca{sup 2+} influx and ATP release mediated by mechanical stretch in human lung fibroblasts

    SciTech Connect

    Murata, Naohiko; Ito, Satoru; Furuya, Kishio; Takahara, Norihiro; Naruse, Keiji; Aso, Hiromichi; Kondo, Masashi; Sokabe, Masahiro; Hasegawa, Yoshinori

    2014-10-10

    Highlights: • Uniaxial stretching activates Ca{sup 2+} signaling in human lung fibroblasts. • Stretch-induced intracellular Ca{sup 2+} elevation is mainly via Ca{sup 2+} influx. • Mechanical strain enhances ATP release from fibroblasts. • Stretch-induced Ca{sup 2+} influx is not mediated by released ATP or actin cytoskeleton. - Abstract: One cause of progressive pulmonary fibrosis is dysregulated wound healing after lung inflammation or damage in patients with idiopathic pulmonary fibrosis and severe acute respiratory distress syndrome. The mechanical forces are considered to regulate pulmonary fibrosis via activation of lung fibroblasts. In this study, the effects of mechanical stretch on the intracellular Ca{sup 2+} concentration ([Ca{sup 2+}]{sub i}) and ATP release were investigated in primary human lung fibroblasts. Uniaxial stretch (10–30% in strain) was applied to fibroblasts cultured in a silicone chamber coated with type I collagen using a stretching apparatus. Following stretching and subsequent unloading, [Ca{sup 2+}]{sub i} transiently increased in a strain-dependent manner. Hypotonic stress, which causes plasma membrane stretching, also transiently increased the [Ca{sup 2+}]{sub i}. The stretch-induced [Ca{sup 2+}]{sub i} elevation was attenuated in Ca{sup 2+}-free solution. In contrast, the increase of [Ca{sup 2+}]{sub i} by a 20% stretch was not inhibited by the inhibitor of stretch-activated channels GsMTx-4, Gd{sup 3+}, ruthenium red, or cytochalasin D. Cyclic stretching induced significant ATP releases from fibroblasts. However, the stretch-induced [Ca{sup 2+}]{sub i} elevation was not inhibited by ATP diphosphohydrolase apyrase or a purinergic receptor antagonist suramin. Taken together, mechanical stretch induces Ca{sup 2+} influx independently of conventional stretch-sensitive ion channels, the actin cytoskeleton, and released ATP.

  5. DAMGO in the central amygdala alleviates the affective dimension of pain in a rat model of inflammatory hyperalgesia.

    PubMed

    Zhang, R-X; Zhang, M; Li, A; Pan, L; Berman, B M; Ren, K; Lao, L

    2013-11-12

    Pain has sensory-discriminative and emotional-affective dimensions. Recent studies show that the affective component can be assessed with a conditioned place avoidance (CPA) test. We hypothesized that systemic morphine before a post-conditioning test would more potently attenuate the affective aspect compared to the sensory component and that [d-Ala2-N-Me-Phe4, Gly-ol5]-enkephalin (DAMGO), a μ-selective opioid receptor agonist, injected into the central nucleus of the amygdala (CeA) would reduce established CPA. A rat model of inflammatory pain, produced by a complete Freund adjuvant (CFA) injection into the hind paw, was combined with a CPA test. Three experiments were performed on adult male Sprague-Dawley rats. Systemic morphine (0.5 or 1.0mg/kg) in Experiment 1, intrathecal (i.t.) morphine (2.5 μg/rat) in Experiment 2, and intra-CeA DAMGO (7.7-15.4 ng/0.4 μl) in Experiment 3 were given to CFA-injected rats (n=6-8/group) prior to a post-conditioning test. Saline-injected rats were used as control. Time spent in a pain-paired compartment was recorded twice, before conditioning and after a post-conditioning test. Paw withdrawal latency (PWL) to a noxious thermal stimulus was measured before experiment at day-1 and after the post-conditioning test; hyperalgesia was defined as a decrease in PWL. The data showed that CFA-injected rats had significantly negative CPA compared to those of saline-injected rats (P<0.05). Low-dosage systemic morphine significantly (P<0.05) reduced CFA-induced CPA but had no effect on PWL. I.t. morphine did not inhibit the display of CPA but significantly increased PWL, suppressing hyperalgesia (P<0.05). Intra-CeA DAMGO significantly inhibited the display of CPA compared to saline (P<0.05) but had no effect on PWL. The data demonstrate that morphine attenuates the affective component more powerfully than it does the sensory and suggests that the sensory and the emotional-affective dimensions are underpinned by different mechanisms.

  6. TRPM2 Channel-Mediated ROS-Sensitive Ca2+ Signaling Mechanisms in Immune Cells

    PubMed Central

    Syed Mortadza, Sharifah Alawieyah; Wang, Lu; Li, Dongliang; Jiang, Lin-Hua

    2015-01-01

    Transient receptor potential melastatin 2 (TRPM2) proteins form Ca2+-permeable cationic channels that are potently activated by reactive oxygen species (ROS). ROS are produced during immune responses as signaling molecules as well as anti-microbial agents. ROS-sensitive TRPM2 channels are widely expressed in cells of the immune system and located on the cell surface as a Ca2+ influx pathway in macrophages, monocytes, neutrophils, lymphocytes, and microglia but preferentially within the lysosomal membranes as a Ca2+ release mechanism in dendritic cells; ROS activation of the TRPM2 channels, regardless of the subcellular location, results in an increase in the intracellular Ca2+ concentrations. Recent studies have revealed that TRPM2-mediated ROS-sensitive Ca2+ signaling mechanisms play a crucial role in a number of processes and functions in immune cells. This mini-review discusses the recent advances in revelation of the various roles the TRPM2 channels have in immune cell functions and the implications in inflammatory diseases. PMID:26300888

  7. Bottom-up and top-down mechanisms indirectly mediate interactions between benthic biotic ecosystem components

    NASA Astrophysics Data System (ADS)

    Van Colen, Carl; Thrush, Simon F.; Parkes, Samantha; Harris, Rachel; Woodin, Sally A.; Wethey, David S.; Pilditch, Conrad A.; Hewitt, Judi E.; Lohrer, Andrew M.; Vincx, Magda

    2015-04-01

    The loss or decline in population size of key species can instigate a cascade of effects that have implications for interacting species, therewith impacting biodiversity and ecosystem functioning. We examined how top-down and bottom-up interactions may mediate knock-on effects of a coastal deposit-feeding clam, Macomona liliana (hereafter Macomona), on sandflat meiobenthos densities. Therefore we manipulated densities of Macomona in combination with predator exclusion and experimental shading that was expected to alter microphytobenthos biomass. We show that Macomona regulated densities of meiobenthic (38-500 μm) nematodes, copepods, polychaetes, turbellarians, and ostracodes during the three months of incubation via indirect mechanisms. Predator pressure on Macomona by eagle rays (Myliobatis tenuicaudatus) was found to have a negative effect on densities of some meiobenthic taxa. Furthermore, experimental shading resulted in the loss of a positive relation between Macomona and microphytobenthos biomass, while concurrently increasing the density of some meiobenthic taxa. We suggest that this observation can be explained by the release from bioturbation interference effects of the cockle Austrovenus stutchburyi that was found to thrive in the presence of Macomona under non-shaded conditions. Our results highlight the importance of interactions between macrofaunal bioturbation, microphyte biomass, sediment stability, and predation pressure for the structuring of benthic communities. This experiment illustrates that manipulative field experiments may be particularly suitable to study such multiple indirect mechanisms that regulate ecosystem diversity and related functioning because such approaches may best capture the complex feedbacks and processes that determine ecosystem dynamics.

  8. Dynamic strain-mediated coupling of a single diamond spin to a mechanical resonator

    PubMed Central

    Ovartchaiyapong, Preeti; Lee, Kenneth W.; Myers, Bryan A.; Jayich, Ania C. Bleszynski

    2014-01-01

    The development of hybrid quantum systems is central to the advancement of emerging quantum technologies, including quantum information science and quantum-assisted sensing. The recent demonstration of high-quality single-crystal diamond resonators has led to significant interest in a hybrid system consisting of nitrogen–vacancy centre spins that interact with the resonant phonon modes of a macroscopic mechanical resonator through crystal strain. However, the nitrogen–vacancy spin–strain interaction has not been well characterized. Here, we demonstrate dynamic, strain-mediated coupling of the mechanical motion of a diamond cantilever to the spin of an embedded nitrogen–vacancy centre. Via quantum control of the spin, we quantitatively characterize the axial and transverse strain sensitivities of the nitrogen–vacancy ground-state spin. The nitrogen–vacancy centre is an atomic scale sensor and we demonstrate spin-based strain imaging with a strain sensitivity of 3 × 10−6 strain Hz−1/2. Finally, we show how this spin-resonator system could enable coherent spin–phonon interactions in the quantum regime. PMID:25034828

  9. Mechanism of arctigenin-mediated specific cytotoxicity against human lung adenocarcinoma cell lines.

    PubMed

    Susanti, Siti; Iwasaki, Hironori; Inafuku, Masashi; Taira, Naoyuki; Oku, Hirosuke

    2013-12-15

    The lignan arctigenin (ARG) from the herb Arctium lappa L. possesses anti-cancer activity, however the mechanism of action of ARG has been found to vary among tissues and types of cancer cells. The current study aims to gain insight into the ARG mediated mechanism of action involved in inhibiting proliferation and inducing apoptosis in lung adenocarcinoma cells. This study also delineates the cancer cell specificity of ARG by comparison with its effects on various normal cell lines. ARG selectively arrested the proliferation of cancer cells at the G0/G1 phase through the down-regulation of NPAT protein expression. This down-regulation occurred via the suppression of either cyclin E/CDK2 or cyclin H/CDK7, while apoptosis was induced through the modulation of the Akt-1-related signaling pathway. Furthermore, a GSH synthase inhibitor specifically enhanced the cytotoxicity of ARG against cancer cells, suggesting that the intracellular GSH content was another factor influencing the susceptibility of cancer cells to ARG. These findings suggest that specific cytotoxicity of ARG against lung cancer cells was explained by its selective modulation of the expression of NPAT, which is involved in histone biosynthesis. The cytotoxicity of ARG appeared to be dependent on the intracellular GSH level.

  10. Mechanism of arctigenin-mediated specific cytotoxicity against human lung adenocarcinoma cell lines.

    PubMed

    Susanti, Siti; Iwasaki, Hironori; Inafuku, Masashi; Taira, Naoyuki; Oku, Hirosuke

    2013-12-15

    The lignan arctigenin (ARG) from the herb Arctium lappa L. possesses anti-cancer activity, however the mechanism of action of ARG has been found to vary among tissues and types of cancer cells. The current study aims to gain insight into the ARG mediated mechanism of action involved in inhibiting proliferation and inducing apoptosis in lung adenocarcinoma cells. This study also delineates the cancer cell specificity of ARG by comparison with its effects on various normal cell lines. ARG selectively arrested the proliferation of cancer cells at the G0/G1 phase through the down-regulation of NPAT protein expression. This down-regulation occurred via the suppression of either cyclin E/CDK2 or cyclin H/CDK7, while apoptosis was induced through the modulation of the Akt-1-related signaling pathway. Furthermore, a GSH synthase inhibitor specifically enhanced the cytotoxicity of ARG against cancer cells, suggesting that the intracellular GSH content was another factor influencing the susceptibility of cancer cells to ARG. These findings suggest that specific cytotoxicity of ARG against lung cancer cells was explained by its selective modulation of the expression of NPAT, which is involved in histone biosynthesis. The cytotoxicity of ARG appeared to be dependent on the intracellular GSH level. PMID:24021157

  11. Atg19 Mediates a Dual Interaction Cargo Sorting Mechanism in Selective Autophagy

    PubMed Central

    Chang, Chiung-Ying

    2007-01-01

    Autophagy is a catabolic membrane-trafficking mechanism conserved in all eukaryotic cells. In addition to the nonselective transport of bulk cytosol, autophagy is responsible for efficient delivery of the vacuolar enzyme Ape1 precursor (prApe1) in the budding yeast Saccharomyces cerevisiae, suggesting the presence of a prApe1 sorting machinery. Sequential interactions between Atg19-Atg11 and Atg19-Atg8 pairs are thought responsible for targeting prApe1 to the vesicle formation site, the preautophagosomal structure (PAS), and loading it into transport vesicles, respectively. However, the different patterns of prApe1 transport defect seen in the atg11Δ and atg19Δ strains seem to be incompatible with this model. Here we report that prApe1 could not be targeted to the PAS and failed to be delivered into the vacuole in atg8Δ atg11Δ double knockout cells regardless of the nutrient conditions. We postulate that Atg19 mediates a dual interaction prApe1-sorting mechanism through independent, instead of sequential, interactions with Atg11 and Atg8. In addition, to efficiently deliver prApe1 to the vacuole, a proper interaction between Atg11 and Atg9 is indispensable. We speculate that Atg11 may elicit a cargo-loading signal and induce Atg9 shuttling to a specific PAS site, where Atg9 relays the signal and recruits other Atg proteins to induce vesicle formation. PMID:17192412

  12. Antidepressants suppress neuropathic pain by a peripheral β2-adrenoceptor mediated anti-TNFα mechanism.

    PubMed

    Bohren, Yohann; Tessier, Luc-Henri; Megat, Salim; Petitjean, Hugues; Hugel, Sylvain; Daniel, Dorothée; Kremer, Mélanie; Fournel, Sylvie; Hein, Lutz; Schlichter, Rémy; Freund-Mercier, Marie-José; Yalcin, Ipek; Barrot, Michel

    2013-12-01

    Neuropathic pain is pain arising as a direct consequence of a lesion or disease affecting the somatosensory system. It is usually chronic and challenging to treat. Some antidepressants are first-line pharmacological treatments for neuropathic pain. The noradrenaline that is recruited by the action of the antidepressants on reuptake transporters has been proposed to act through β2-adrenoceptors (β2-ARs) to lead to the observed therapeutic effect. However, the complex downstream mechanism mediating this action remained to be identified. In this study, we demonstrate in a mouse model of neuropathic pain that an antidepressant's effect on neuropathic allodynia involves the peripheral nervous system and the inhibition of cytokine tumor necrosis factor α (TNFα) production. The antiallodynic action of nortriptyline is indeed lost after peripheral sympathectomy, but not after lesion of central descending noradrenergic pathways. More particularly, we report that antidepressant-recruited noradrenaline acts, within dorsal root ganglia, on β2-ARs expressed by non-neuronal satellite cells. This stimulation of β2-ARs decreases the neuropathy-induced production of membrane-bound TNFα, resulting in relief of neuropathic allodynia. This indirect anti-TNFα action was observed with the tricyclic antidepressant nortriptyline, the selective serotonin and noradrenaline reuptake inhibitor venlafaxine and the β2-AR agonist terbutaline. Our data revealed an original therapeutic mechanism that may open novel research avenues for the management of painful peripheral neuropathies. PMID:23978467

  13. Internalisation of the bleomycin molecules responsible for bleomycin toxicity: a receptor-mediated endocytosis mechanism.

    PubMed

    Pron, G; Mahrour, N; Orlowski, S; Tounekti, O; Poddevin, B; Belehradek, J; Mir, L M

    1999-01-01

    Bleomycin (BLM) does not diffuse through the plasma membrane but nevertheless displays cytotoxic activity due to DNA break generation. The aim of the study was to describe the mechanism of BLM internalisation. We previously provided evidence for the existence of BLM-binding sites at the surface of DC-3F Chinese hamster fibroblasts, as well as of their involvement in BLM cytotoxicity on DC-3F cells and related BLM-resistant sublines. Here we report that A253 human cells and their BLM-resistant subline C-10E also possessed a membrane protein of ca. 250 kDa specifically binding BLM. Part of this C-10E cell resistance could be explained by a decrease in the number of BLM-binding sites exposed at the cell surface with respect to A253 cells. The comparison between A253 and DC-3F cells exposing a similar number of BLM-binding sites revealed that the faster the fluid phase endocytosis, the greater the cell sensitivity to BLM. Moreover, the experimental modification of endocytotic vesicle size showed that BLM cytotoxicity was directly correlated with the flux of plasma membrane area engulfed during endocytosis rather than with the fluid phase volume incorporated. Thus, BLM would be internalised by a receptor-mediated endocytosis mechanism which would first require BLM binding to its membrane receptor and then the transfer of the complex into intracellular endocytotic vesicles, followed by BLM entry into the cytosol, probably from a nonacidic compartment.

  14. Aire mediates thymic expression and tolerance of pancreatic antigens via an unconventional transcriptional mechanism.

    PubMed

    Danso-Abeam, Dina; Staats, Kim A; Franckaert, Dean; Van Den Bosch, Ludo; Liston, Adrian; Gray, Daniel H D; Dooley, James

    2013-01-01

    The autoimmune regulator (Aire), mediates central tolerance of peripheral self. Its activity in thymic epithelial cells (TECs) directs the ectopic expression of thousands of tissue-restricted antigens (TRAs), causing the deletion of autoreactive thymocytes. The molecular mechanisms orchestrating the breadth of transcriptional regulation by Aire remain unknown. One prominent model capable of explaining both the uniquely high number of Aire-dependent targets and their specificity posits that tissue-specific transcription factors induced by Aire directly activate their canonical targets, exponentially adding to the total number of Aire-dependent TRAs. To test this "Hierarchical Transcription" model, we analysed mice deficient in the pancreatic master transcription factor pancreatic and duodenal homeobox 1 (Pdx1), specifically in TECs (Pdx1(ΔFoxn1) ), for the expression and tolerance of pancreatic TRAs. Surprisingly, we found that lack of Pdx1 in TECs did not reduce the transcription of insulin or somatostatin, or alter glucagon expression. Moreover, in a model of thymic deletion driven by a neo-TRA under the control of the insulin promoter, Pdx1 in TECs was not required to affect thymocyte deletion or the generation of regulatory T (Treg) cells. These findings suggest that the capacity of Aire to regulate expression of a huge array of TRAs relies solely on an unconventional transcriptional mechanism, without intermediary transcription factors.

  15. Mechanisms of the ultrasound-mediated intracellular delivery of liposomes and dextrans.

    PubMed

    Afadzi, Mercy; Strand, Sabina P; Nilssen, Esben A; Måsøy, Svein-Erik; Johansen, Tonni F; Hansen, Rune; Angelsen, Bjørn A; de L Davies, Catharina

    2013-01-01

    The mechanism involved in the ultrasoundenhanced intracellular delivery of fluorescein-isothiocyanate (FITC)-dextran (molecular weight 4 to 2000 kDa) and liposomes containing doxorubicin (Dox) was studied using HeLa cells and an ultrasound transducer at 300 kHz, varying the acoustic power. The cellular uptake and cell viability were measured using flow cytometry and confocal microscopy. The role of endocytosis was investigated by inhibiting clathrin- and caveolae-mediated endocytosis, as well as macropinocytosis. Microbubbles were found to be required during ultrasound treatment to obtain enhanced cellular uptake. The percentage of cells internalizing Dox and dextran increased with increasing mechanical index. Confocal images and flow cytometric analysis indicated that the liposomes were disrupted extracellularly and that released Dox was taken up by the cells. The percentage of cells internalizing dextran was independent of the molecular weight of dextrans, but the amount of the small 4-kDa dextran molecules internalized per cell was higher than for the other dextrans. The inhibition of endocytosis during ultrasound exposure resulted in a significant decrease in cellular uptake of dextrans. Therefore, the improved uptake of Dox and dextrans may be a result of both sonoporation and endocytosis.

  16. Mechanism of Microhomology-Mediated End-Joining Promoted by Human DNA Polymerase Theta

    PubMed Central

    Kent, Tatiana; Chandramouly, Gurushankar; McDevitt, Shane Michael; Ozdemir, Ahmet Y.; Pomerantz, Richard T.

    2014-01-01

    Microhomology-mediated end-joining (MMEJ) is an error-prone alternative double-strand break repair pathway that utilizes sequence microhomology to recombine broken DNA. Although MMEJ is implicated in cancer development, the mechanism of this pathway is unknown. We demonstrate that purified human DNA polymerase θ (Polθ) performs MMEJ of DNA containing 3’ single-strand DNA overhangs with two or more base-pairs of homology, including DNA modeled after telomeres, and show that MMEJ is dependent on Polθ in human cells. Our data support a mechanism whereby Polθ facilitates end-joining and microhomology annealing then utilizes the opposing overhang as a template in trans which stabilizes the DNA synapse. Polθ exhibits a preference for DNA containing a 5’-terminal phosphate, similar to polymerases involved in non-homologous end-joining. Lastly, we identify a conserved loop domain that is essential for MMEJ and higher-order structures of Polθ which likely promote DNA synapse formation. PMID:25643323

  17. Enhanced brain responses to C-fiber input in the area of secondary hyperalgesia induced by high-frequency electrical stimulation of the skin

    PubMed Central

    Mouraux, André

    2014-01-01

    High-frequency electrical stimulation (HFS) of the human skin induces an increase in both mechanical and heat pain sensitivity in the surrounding unconditioned skin. The aim of this study was to investigate the effect of HFS on the intensity of perception and brain responses elicited by the selective activation of C fibers. HFS was applied to the ventral forearm of 15 healthy volunteers. Temperature-controlled CO2 laser stimulation was used to activate selectively low-threshold C-fiber afferents without concomitantly activating Aδ-fiber afferents. These stimuli were detected with reaction times compatible with the conduction velocity of C fibers. The intensity of perception and event-related brain potentials (ERPs) elicited by thermal stimuli delivered to the surrounding unconditioned skin were recorded before (T0) and after HFS (T1: 20 min after HFS; T2: 45 min after HFS). The contralateral forearm served as a control. Mechanical hyperalgesia following HFS was confirmed by measuring the change in the intensity of perception elicited by mechanical punctate stimuli. HFS resulted in increased intensity of perception to mechanical punctate stimulation and selective C-fiber thermal stimulation at both time points. In contrast, the N2 wave of the ERP elicited by C-fiber stimulation (679 ± 88 ms; means ± SD) was enhanced at T1 but not at T2. The P2 wave (808 ± 105 ms) was unaffected by HFS. Our results suggest that HFS enhances the sensitivity to thermal C-fiber input in the area of secondary hyperalgesia. However, there was no significant enhancement of the magnitude of the C-fiber ERPs at T2, suggesting that quickly adapting C fibers do not contribute to this enhancement. PMID:25098966

  18. Mechanisms in the PVN mediating local and central sodium-induced hypertension in Wistar rats.

    PubMed

    Gabor, Alexander; Leenen, Frans H H

    2009-03-01

    Sympathoexcitatory and hypertensive responses to central infusion of Na(+)-rich artificial cerebrospinal fluid (aCSF) are enhanced by aldosterone and mediated by mineralocorticoid receptors (MRs) and benzamil-blockable Na(+) influx, leading to "ouabain" release and ANG II type 1 (AT(1)) receptor stimulation. The present study evaluated the functional role of these mechanisms in the paraventricular nucleus (PVN). In conscious Wistar rats, Na(+)-rich aCSF was infused either directly into the PVN or intracerebroventricularly preceded by aldosterone and blockers. Infusion of Na(+)-rich aCSF in the PVN caused gradual increases in blood pressure (BP) and heart rate (HR). Aldosterone and a subpressor dose of ouabain in the PVN alone did not affect BP and HR but enhanced responses to Na(+). Eplerenone, benzamil, and "ouabain"-binding Fab fragments only blocked the enhancement by aldosterone, whereas losartan blocked all responses to Na(+)-rich aCSF in the PVN. Increases in BP and HR by intracerebroventricular infusion of Na(+)-rich aCSF were enhanced by aldosterone infused intracerebroventricularly, but not in the PVN. Telmisartan in the PVN again blocked all responses. In contrast, both eplerenone and benzamil in the PVN did not change the pressor responses to intracerebroventricular infusion of aldosterone and Na(+)-rich aCSF. These findings indicate that AT(1) receptors in the PVN mediate the responses to Na(+)-rich aCSF and their enhancement by aldosterone, both locally in the PVN or in the general CSF. MRs, benzamil-blockable Na(+) channels or transporters, and "ouabain" can be functionally active in the PVN, but in Wistar rats appear not to contribute to the pressor responses to short-term increases in CSF [Na(+)].

  19. MAPK signaling cascades mediate distinct glucocorticoid resistance mechanisms in pediatric leukemia

    PubMed Central

    Jones, Courtney L.; Gearheart, Christy M.; Fosmire, Susan; Delgado-Martin, Cristina; Evensen, Nikki A.; Bride, Karen; Waanders, Angela J.; Pais, Faye; Wang, Jinhua; Bhatla, Teena; Bitterman, Danielle S.; de Rijk, Simone R.; Bourgeois, Wallace; Dandekar, Smita; Park, Eugene; Burleson, Tamara M.; Madhusoodhan, Pillai Pallavi; Teachey, David T.; Raetz, Elizabeth A.; Hermiston, Michelle L.; Müschen, Markus; Loh, Mignon L.; Hunger, Stephen P.; Zhang, Jinghui; Garabedian, Michael J.; Porter, Christopher C.

    2015-01-01

    The outcome for pediatric acute lymphoblastic leukemia (ALL) patients who relapse is dismal. A hallmark of relapsed disease is acquired resistance to multiple chemotherapeutic agents, particularly glucocorticoids. In this study, we performed a genome-scale short hairpin RNA screen to identify mediators of prednisolone sensitivity in ALL cell lines. The incorporation of these data with an integrated analysis of relapse-specific genetic and epigenetic changes allowed us to identify the mitogen-activated protein kinase (MAPK) pathway as a mediator of prednisolone resistance in pediatric ALL. We show that knockdown of the specific MAPK pathway members MEK2 and MEK4 increased sensitivity to prednisolone through distinct mechanisms. MEK4 knockdown increased sensitivity specifically to prednisolone by increasing the levels of the glucocorticoid receptor. MEK2 knockdown increased sensitivity to all chemotherapy agents tested by increasing the levels of p53. Furthermore, we demonstrate that inhibition of MEK1/2 with trametinib increased sensitivity of ALL cells and primary samples to chemotherapy in vitro and in vivo. To confirm a role for MAPK signaling in patients with relapsed ALL, we measured the activation of the MEK1/2 target ERK in matched diagnosis-relapse primary samples and observed increased phosphorylated ERK levels at relapse. Furthermore, relapse samples have an enhanced response to MEK inhibition compared to matched diagnosis samples in xenograft models. Together, our data indicate that inhibition of the MAPK pathway increases chemosensitivity to glucocorticoids and possibly other agents and that the MAPK pathway is an attractive target for prevention and/or treatment of relapsed disease. PMID:26324703

  20. MAPK signaling cascades mediate distinct glucocorticoid resistance mechanisms in pediatric leukemia.

    PubMed

    Jones, Courtney L; Gearheart, Christy M; Fosmire, Susan; Delgado-Martin, Cristina; Evensen, Nikki A; Bride, Karen; Waanders, Angela J; Pais, Faye; Wang, Jinhua; Bhatla, Teena; Bitterman, Danielle S; de Rijk, Simone R; Bourgeois, Wallace; Dandekar, Smita; Park, Eugene; Burleson, Tamara M; Madhusoodhan, Pillai Pallavi; Teachey, David T; Raetz, Elizabeth A; Hermiston, Michelle L; Müschen, Markus; Loh, Mignon L; Hunger, Stephen P; Zhang, Jinghui; Garabedian, Michael J; Porter, Christopher C; Carroll, William L

    2015-11-01

    The outcome for pediatric acute lymphoblastic leukemia (ALL) patients who relapse is dismal. A hallmark of relapsed disease is acquired resistance to multiple chemotherapeutic agents, particularly glucocorticoids. In this study, we performed a genome-scale short hairpin RNA screen to identify mediators of prednisolone sensitivity in ALL cell lines. The incorporation of these data with an integrated analysis of relapse-specific genetic and epigenetic changes allowed us to identify the mitogen-activated protein kinase (MAPK) pathway as a mediator of prednisolone resistance in pediatric ALL. We show that knockdown of the specific MAPK pathway members MEK2 and MEK4 increased sensitivity to prednisolone through distinct mechanisms. MEK4 knockdown increased sensitivity specifically to prednisolone by increasing the levels of the glucocorticoid receptor. MEK2 knockdown increased sensitivity to all chemotherapy agents tested by increasing the levels of p53. Furthermore, we demonstrate that inhibition of MEK1/2 with trametinib increased sensitivity of ALL cells and primary samples to chemotherapy in vitro and in vivo. To confirm a role for MAPK signaling in patients with relapsed ALL, we measured the activation of the MEK1/2 target ERK in matched diagnosis-relapse primary samples and observed increased phosphorylated ERK levels at relapse. Furthermore, relapse samples have an enhanced response to MEK inhibition compared to matched diagnosis samples in xenograft models. Together, our data indicate that inhibition of the MAPK pathway increases chemosensitivity to glucocorticoids and possibly other agents and that the MAPK pathway is an attractive target for prevention and/or treatment of relapsed disease.

  1. Warming Moxibustion Relieves Chronic Visceral Hyperalgesia in Rats: Relations to Spinal Dynorphin and Orphanin-FQ System

    PubMed Central

    Qi, Li; Liu, Hui-Rong; Yi, Tao; Wu, Lu-Yi; Liu, Xi-Ru; Zhao, Chen; Shi, Yin; Ma, Xiao-Peng; Wu, Huan-Gan

    2013-01-01

    As a twin therapy of acupuncture in traditional Chinese medicine, moxibustion has shown its effects in relieving abdominal pain in irritable bowel syndrome (IBS) patients and IBS rat models, but its mechanisms are largely unknown. In this paper, we determined the role of spinal dynorphin and orphanin-FQ system in analgesic effect of warming moxibustion (WM) on chronic visceral hyperalgesia (CVH) in IBS-like rat model. Here, we show that (1) repeated WM at bilateral ST25 and ST37 acupoints markedly attenuated the abdominal withdrawal reflex scores in CVH rats; (2) intrathecal administration of κ receptor antagonist prior to WM significantly attenuated the WM analgesia and dynorphinA (1-17) enhanced the WM analgesia. WM significantly reinforced the upregulation of spinal dynorphin mRNA/protein and κ receptor mRNA levels in CVH rats; (3) intrathecal administration of orphanin-FQ receptor antagonist prior to WM significantly attenuated the WM analgesia and orphanin-FQ enhanced the WM analgesia. WM reinforced the upregulation of spinal orphanin-FQ mRNA/protein and orphanin-FQ receptor mRNA levels in CVH rats. These results suggest that moxibustion may relieve CVH at least in part by activating spinal dynorphin and orphanin-FQ system. PMID:23573158

  2. Electroacupuncture Inhibition of Hyperalgesia in Rats with Adjuvant Arthritis: Involvement of Cannabinoid Receptor 1 and Dopamine Receptor Subtypes in Striatum

    PubMed Central

    Shou, Yin; Yang, Yang; Xu, Ming-Shu; Zhao, Ying-Qian; Ge, Lin-Bao; Zhang, Bi-Meng

    2013-01-01

    Electroacupuncture (EA) has been regarded as an alternative treatment for inflammatory pain for several decades. However, the molecular mechanisms underlying the antinociceptive effect of EA have not been thoroughly clarified. Previous studies have shown that cannabinoid CB1 receptors are related to pain relief. Accumulating evidence has shown that the CB1 and dopamine systems sometimes interact and may operate synergistically in rat striatum. To our knowledge, dopamine D1/D2 receptors are involved in EA analgesia. In this study, we found that repeated EA at Zusanli (ST36) and Kunlun (BL60) acupoints resulted in marked improvements in thermal hyperalgesia. Both western blot assays and FQ-PCR analysis results showed that the levels of CB1 expression in the repeated-EA group were much higher than those in any other group (P = 0.001). The CB1-selective antagonist AM251 inhibited the effects of repeated EA by attenuating the increases in CB1 expression. The two kinds of dopamine receptors imparted different actions on the EA-induced CB1 upregulation in AA rat model. These results suggested that the strong activation of the CB1 receptor after repeated EA resulted in the concomitant phenomenon of the upregulation of D1 and D2 levels of gene expression. PMID:23762129

  3. Molecular Mechanisms Mediating the Adaptive Regulation of Intestinal Riboflavin Uptake Process.

    PubMed

    Subramanian, Veedamali S; Ghosal, Abhisek; Kapadia, Rubina; Nabokina, Svetlana M; Said, Hamid M

    2015-01-01

    The intestinal absorption process of vitamin B2 (riboflavin, RF) is carrier-mediated, and all three known human RF transporters, i.e., hRFVT-1, -2, and -3 (products of the SLC52A1, 2 & 3 genes, respectively) are expressed in the gut. We have previously shown that the intestinal RF uptake process is adaptively regulated by substrate level, but little is known about the molecular mechanism(s) involved. Using human intestinal epithelial NCM460 cells maintained under RF deficient and over-supplemented (OS) conditions, we now show that the induction in RF uptake in RF deficiency is associated with an increase in expression of the hRFVT-2 & -3 (but not hRFVT-1) at the protein and mRNA levels. Focusing on hRFVT-3, the predominant transporter in the intestine, we also observed an increase in the level of expression of its hnRNA and activity of its promoter in the RF deficiency state. An increase in the level of expression of the nuclear factor Sp1 (which is important for activity of the SLC52A3 promoter) was observed in RF deficiency, while mutating the Sp1/GC site in the SLC52A3 promoter drastically decreased the level of induction in SLC52A3 promoter activity in RF deficiency. We also observed specific epigenetic changes in the SLC52A3 promoter in RF deficiency. Finally, an increase in hRFVT-3 protein expression at the cell surface was observed in RF deficiency. Results of these investigations show, for the first time, that transcriptional and post-transcriptional mechanisms are involved in the adaptive regulation of intestinal RF uptake by the prevailing substrate level.

  4. Molecular Mechanisms Mediating the Adaptive Regulation of Intestinal Riboflavin Uptake Process

    PubMed Central

    Subramanian, Veedamali S.; Ghosal, Abhisek; Kapadia, Rubina; Nabokina, Svetlana M.; Said, Hamid M.

    2015-01-01

    The intestinal absorption process of vitamin B2 (riboflavin, RF) is carrier-mediated, and all three known human RF transporters, i.e., hRFVT-1, -2, and -3 (products of the SLC52A1, 2 & 3 genes, respectively) are expressed in the gut. We have previously shown that the intestinal RF uptake process is adaptively regulated by substrate level, but little is known about the molecular mechanism(s) involved. Using human intestinal epithelial NCM460 cells maintained under RF deficient and over-supplemented (OS) conditions, we now show that the induction in RF uptake in RF deficiency is associated with an increase in expression of the hRFVT-2 & -3 (but not hRFVT-1) at the protein and mRNA levels. Focusing on hRFVT-3, the predominant transporter in the intestine, we also observed an increase in the level of expression of its hnRNA and activity of its promoter in the RF deficiency state. An increase in the level of expression of the nuclear factor Sp1 (which is important for activity of the SLC52A3 promoter) was observed in RF deficiency, while mutating the Sp1/GC site in the SLC52A3 promoter drastically decreased the level of induction in SLC52A3 promoter activity in RF deficiency. We also observed specific epigenetic changes in the SLC52A3 promoter in RF deficiency. Finally, an increase in hRFVT-3 protein expression at the cell surface was observed in RF deficiency. Results of these investigations show, for the first time, that transcriptional and post-transcriptional mechanisms are involved in the adaptive regulation of intestinal RF uptake by the prevailing substrate level. PMID:26121134

  5. Probing the Role of HDACs and Mechanisms of Chromatin-Mediated Neuroplasticity

    PubMed Central

    Haggarty, Stephen J.; Tsai, Li-Huei

    2011-01-01

    Advancing our understanding of neuroplasticity and the development of novel therapeutics based upon this knowledge is critical in order to improve the treatment and prevention of a myriad of nervous system disorders. Epigenetic mechanisms of neuroplasticity involve the post-translational modification of chromatin and the recruitment or loss of macromolecular complexes that control neuronal activity-dependent gene expression. While over a century after Ramón y Cajal first described nuclear subcompartments and foci that we now know correspond to sites of active transcription with acetylated histones that are under epigenetic control, the rate and extent to which epigenetic processes act in a dynamic and combinatorial fashion to shape experience-dependent phenotypic and behavioral plasticity in response to various types of neuronal stimuli over a range of time scales is only now coming into focus. With growing recognition that a subset of human diseases involving cognitive dysfunction can be classified as ‘chromatinopathies’, in which aberrant chromatin-mediated neuroplasticity plays a causal role in the underlying disease pathophysiology, understanding the molecular nature of epigenetic mechanisms in the nervous system may provide important new avenues for the development of novel therapeutics. In this review, we discuss the chemistry and neurobiology of the histone deacetylase (HDAC) family of chromatin-modifying enzymes, outline the role of HDACs in the epigenetic control of neuronal function, and discuss the potential relevance of these epigenetic mechanisms to the development of therapeutics aiming to enhance memory and neuroplasticity. Finally, open questions, challenges, and critical needs for the field of ‘neuroepigenetics’ in the years to come will be summarized. PMID:21545841

  6. Rejection Triggers Liver Transplant Tolerance: Involvements of Mesenchyme-Mediated Immune Control Mechanisms

    PubMed Central

    Morita, Miwa; Joyce, Daniel; Miller, Charles; Fung, John J.; Lu, Lina; Qian, Shiguang

    2015-01-01

    Liver tolerance was initially recognized by the spontaneous acceptance of liver allograft in many species. The underlying mechanisms are not completely understood. We have been inspired by an unexpected phenomenon that the liver transplant tolerance absolutely requires interferon (IFN)-γ, a rejection-associated inflammatory cytokine. In this study, we investigate the rejection of liver allografts deficient in IFN-γ receptor and reveal that the liver graft is equipped with machineries capable of counterattacking the host immune response through a mesenchyme-mediated immune control (MMIC) mechanism. MMIC is triggered by T effectors (Tef) cell-derived IFN-γ to drive the expression of B7-H1 on graft mesenchymal cells leading to Tef cell apoptosis. We describe the negative feedback loop between graft mesenchymal and Tef cells that ultimately results in liver transplant tolerance. Comparable elevations of T regulatory cells and myeloid-derived suppressor cells are seen in both rejection and tolerance groups, and are not dependent on IFN-γ stimulation, suggesting a critical role of Tef cell elimination in tolerance induction. We identify potent MMIC activity in hepatic stellate cells and liver sinusoidal endothelial cells. MMIC is unlikely exclusive to the liver, as spontaneous acceptance of kidney allografts has been reported, although less commonly, probably reflecting variance in MMIC activity. MMCI may represent an important homeostatic mechanism that supports peripheral tolerance, and could be a target for the prevention and treatment of transplant rejection. This study highlights that the graft is actively participant in the equipoise between tolerance and rejection and warrants more attention in the search for tolerance biomarkers. PMID:25998530

  7. Self-injurious behavior in neurodevelopmental disorders: relevance of nociceptive and immune mechanisms.

    PubMed

    Symons, Frank J

    2011-04-01

    Self-injurious behavior (SIB) among individuals with intellectual and related neurodevelopmental disorders (IDD) is a clinical challenge and scientific puzzle. The physiological mechanisms regulating the sensory components of SIB remain a mystery with no clear understanding of the underlying pathophysiology. The central dogma regarding sensory processing in general and pain in particular among individuals with IDD and chronic SIB is that sensory processing is reduced and pain is absent or blunted. In this paper, recent findings challenging some of the conventional wisdom regarding pain and sensory function among individuals with IDD and SIB are reviewed. It seems that at least a subgroup of individuals with IDD and chronic SIB may be in a physiological state similar to neuropathic pain in which hyperalgesia is mediated by plasticity mechanisms regulating inflammatory, immune, and nociceptive systems. In response to repeated tissue damage associated with chronic self-injury, innate immune cells may be producing pro-inflammatory and pro-nociceptive cytokines that act on the brain to cause sickness-like behavior and sensitize primary sensory nerve afferents contributing to pain hypersensitivity (i.e., hyperalgesia). PMID:21237197

  8. A carrier-mediated mechanism for pyridoxine uptake by human intestinal epithelial Caco-2 cells: regulation by a PKA-mediated pathway.

    PubMed

    Said, Hamid M; Ortiz, Alvaro; Ma, Thomas Y

    2003-11-01

    Vitamin B6 is essential for cellular functions and growth due to its involvement in important metabolic reactions. Humans and other mammals cannot synthesize vitamin B6 and thus must obtain this micronutrient from exogenous sources via intestinal absorption. The intestine, therefore, plays a central role in maintaining and regulating normal vitamin B6 homeostasis. Due to the water-soluble nature of vitamin B6 and the demonstration that transport of other water-soluble vitamins in intestinal epithelial cells involves specialized carrier-mediated mechanisms, we hypothesized that transport of vitamin B6 in these cells is also carrier mediated in nature. To test this hypothesis, we examined pyridoxine transport in a model system for human enterocytes, the human-derived intestinal epithelial Caco-2 cells. The results showed pyridoxine uptake to be 1) linear with time for up to 10 min of incubation and to occur with minimal metabolic alteration in the transported substrate, 2) temperature and energy dependent but Na+ independent, 3) pH dependent with higher uptake at acidic compared with alkaline pHs, 4) saturable as a function of concentration (at buffer pH 5.5 but not 7.4) with an apparent Michaelis-Menten constant (Km) of 11.99 +/- 1.41 microM and a maximal velocity (Vmax) of 67.63 +/- 3.87 pmol. mg protein-1. 3 min-1, 5) inhibited by pyridoxine structural analogs (at buffer pH 5.5 but not 7.4) but not by unrelated compounds, and 6) inhibited in a competitive manner by amiloride with an apparent inhibitor constant (Ki) of 0.39 mM. We also examined the possible regulation of pyridoxine uptake by specific intracellular regulatory pathways. The results showed that whereas modulators of PKC, Ca+2/calmodulin (CaM), and nitric oxide (NO)-mediated pathways had no effect on pyridoxine uptake, modulators of PKA-mediated pathway were found to cause significant reduction in pyridoxine uptake. This reduction was mediated via a significant inhibition in the Vmax, but not the

  9. Arabinosylated lipoarabinomannan (Ara-LAM) mediated intracellular mechanisms against tuberculosis infection: involvement of protein kinase C (PKC) mediated signaling.

    PubMed

    Das, Shibali; Bhattacharjee, Oindrila; Goswami, Avranil; Pal, Nishith K; Majumdar, Subrata

    2015-03-01

    Tuberculosis causes severe immunosuppression thereby ensuring the loss of the host protective immune responses. During Mycobacterium tuberculosis infection, the pathogen modulates TLR-2 receptor down-stream signaling, indicating the possible involvement of TLR-2 in the regulation of the host immune response. Moreover, different PKC isoforms are also involved in the course of infection. Arabinosylated lipoarabinomannan (Ara-LAM) possesses immuno-modulatory properties which induce the pro-inflammatory responses via induction of TLR-2-mediated signaling. Here, we found that pretreatment of M. tuberculosis-infected macrophages with Ara-LAM caused a significant increase in the conventional PKC expression along with their active association with TLR-2. This association activated the TLR-2 -mediated downstream signaling, facilitating the activation of MAP kinase P38. All these events culminated in the up-regulation of proinflammatory response, which was abrogated by treatment with PKC-α and P38 inhibitors. Moreover, pretreatment of macrophages with Ara-LAM abrogated the IL-10 production while restored MHC-II expression in the infected macrophages. This study demonstrates that Ara-LAM confers protection against tuberculosis via TLR-2/PKC signaling crosstalk which is responsible for the induction of host protective immune response against tuberculosis.

  10. β-arrestin-1 mediates the TCR-triggered re-routing of distal receptors to the immunological synapse by a PKC-mediated mechanism

    PubMed Central

    Fernández-Arenas, Elena; Calleja, Enrique; Martínez-Martín, Nadia; Gharbi, Severine I; Navajas, Rosana; García-Medel, Noel; Penela, Petronila; Alcamí, Antonio; Mayor, Federico; Albar, Juan P; Alarcón, Balbino

    2014-01-01

    T-cell receptors (TCR) recognize their antigen ligand at the interface between T cells and antigen-presenting cells, known as the immunological synapse (IS). The IS provides a means of sustaining the TCR signal which requires the continual supply of new TCRs. These are endocytosed and redirected from distal membrane locations to the IS. In our search for novel cytoplasmic effectors, we have identified β-arrestin-1 as a ligand of non-phosphorylated resting TCRs. Using dominant-negative and knockdown approaches we demonstrate that β-arrestin-1 is required for the internalization and downregulation of non-engaged bystander TCRs. Furthermore, TCR triggering provokes the β-arrestin-1-mediated downregulation of the G-protein coupled chemokine receptor CXCR4, but not of other control receptors. We demonstrate that β-arrestin-1 recruitment to the TCR, and bystander TCR and CXCR4 downregulation, are mechanistically mediated by the TCR-triggered PKC-mediated phosphorylation of β-arrestin-1 at Ser163. This mechanism allows the first triggered TCRs to deliver a stop migration signal, and to promote the internalization of distal TCRs and CXCR4 and their translocation to the IS. This receptor crosstalk mechanism is critical to sustain the TCR signal. PMID:24502978

  11. Superinduction of estrogen receptor mediated gene expression in luciferase based reporter gene assays is mediated by a post-transcriptional mechanism.

    PubMed

    Sotoca, A M; Bovee, T F H; Brand, W; Velikova, N; Boeren, S; Murk, A J; Vervoort, J; Rietjens, I M C M

    2010-10-01

    Several estrogenic compounds including the isoflavonoid genistein have been reported to induce a higher maximal response than the natural estrogen 17β-estradiol in in vitro luciferase based reporter gene bioassays for testing estrogenicity. The phenomenon has been referred to as superinduction. The mechanism underlying this effect and thus also its biological relevance remain to be elucidated. In the present study several hypotheses for the possible mechanisms underlying this superinduction were investigated using genistein as the model compound. These hypotheses included (i) a non-estrogen receptor (ER)-mediated mechanism, (ii) a role for an ER activating genistein metabolite with higher ER inducing activity than genistein itself, and (iii) a post-transcriptional mechanism that is not biologically relevant but specific for the luciferase based reporter gene assays. The data presented in this study indicate that induction and also superinduction of the reporter gene is ER-mediated, and that superinduction by genistein could be ascribed to stabilization of the firefly luciferase reporter enzyme increasing the bioluminescent signal during the cell-based assay. This indicates that the phenomenon of superinduction may not be biologically relevant but may rather represent a post-transcriptional effect on enzyme stability.

  12. Exploring How School Intra-Organizational Mechanisms Mediate the Effects of External Interventions on Improving Teaching and Learning

    ERIC Educational Resources Information Center

    Sun, Min

    2011-01-01

    This dissertation collects three independent but interrelated studies exploring how school intra-organizational mechanism may mediate the impact of external interventions on improving teaching and learning. This first study examines how high-quality professional development (PD) can promote the diffusion of effective teaching strategies among…

  13. Amine oxidation mediated by lysine-specific demethylase 1: quantum mechanics/molecular mechanics insights into mechanism and role of lysine 661.

    PubMed

    Karasulu, Bora; Patil, Mahendra; Thiel, Walter

    2013-09-11

    We report classical molecular dynamics (MD) simulations and combined quantum mechanics/molecular mechanics (QM/MM) calculations to elucidate the catalytic mechanism of the rate-determining amine oxidation step in the lysine-specific demethylase 1 (LSD1)-catalyzed demethylation of the histone tail lysine (H3K4), with flavin adenine dinucleotide (FAD) acting as cofactor. The oxidation of substrate lysine (sLys) involves the cleavage of an α-CH bond accompanied by the transfer of a hydride ion equivalent to FAD, leading to an imine intermediate. This hydride transfer pathway is shown to be clearly favored for sLys oxidation over other proposed mechanisms, including the radical (or single-electron transfer) route as well as carbanion and polar-nucleophilic mechanisms. MD simulations on six NVT ensembles (covering different protonation states of sLys and K661 as well as the K661M mutant) identify two possible orientations of the reacting sLys and FAD subunits (called "downward" and "upward"). Calculations at the QM(B3LYP-D/6-31G*)/CHARMM22 level provide molecular-level insights into the mechanism, helping to understand how LSD1 achieves the activation of the rather inert methyl-CH bond in a metal-free environment. Factors such as proper alignment of sLys (downward orientation), transition-state stabilization (due to the protein environment and favorable orbital interactions), and product stabilization via adduct formation are found to be crucial for facilitating the oxidative α-CH bond cleavage. The current study also sheds light on the role of important active-site residues (Y761, K661, and W695) and of the conserved water-bridge motif. The steric influence of Y761 helps to position the reaction partners properly, K661 is predicted to get deprotonated prior to substrate binding and to act as an active-site base that accepts a proton from sLys to enable the subsequent amine oxidation, and the water bridge that is stabilized by K661 and W695 mediates this proton

  14. Therapeutic targeting of myeloid-derived suppressor cells involves a novel mechanism mediated by clusterin.

    PubMed

    Zhou, Junmin; Donatelli, Sarah S; Gilvary, Danielle L; Tejera, Melba M; Eksioglu, Erika A; Chen, Xianghong; Coppola, Domenico; Wei, Sheng; Djeu, Julie Y

    2016-01-01

    Myeloid-derived suppressor cells (MDSCs) constitute a key checkpoint that impedes tumor immunity against cancer. Chemotherapeutic intervention of MDSCs has gained ground as a strategy for cancer therapy but its mechanism remains obscure.We report here a unique mechanism by which monocytic (M)-MDSCs are spared, allowing them to polarize towards M1 macrophages for reactivation of immunity against breast cancer. We first demonstrated that curcumin, like docetaxel (DTX), can selectively target CD11b(+)Ly6G(+)Ly6C(low) granulocytic (G)-MDSCs, sparing CD11b(+)Ly6G(-)Ly6C(high) M-MDSCs, with reduced tumor burden in 4T1-Neu tumor-bearing mice. Curcumin treatment polarized surviving M-MDSCs toward CCR7(+) Dectin-1(-)M1 cells, accompanied by IFN-γ production and cytolytic function in T cells. Selective M-MDSC chemoresistence to curcumin and DTX was mediated by secretory/cytoplasmic clusterin (sCLU). sCLU functions by trapping Bax from mitochondrial translocation, preventing the apoptotic cascade. Importantly, sCLU was only found in M-MDSCs but not in G-MDSCs. Knockdown of sCLU in M-MDSCs and RAW264.7 macrophages was found to reverse their natural chemoresistance. Clinically, breast cancer patients possess sCLU expression only in mature CD68(+) macrophages but not in immature CD33(+) immunosuppressive myeloid cells infiltrating the tumors. We thus made the seminal discovery that sCLU expression in M-MDSCs accounts for positive immunomodulation by chemotherapeutic agents. PMID:27405665

  15. Plasmid-Mediated OqxAB Is an Important Mechanism for Nitrofurantoin Resistance in Escherichia coli.

    PubMed

    Ho, Pak-Leung; Ng, Ka-Ying; Lo, Wai-U; Law, Pierra Y; Lai, Eileen Ling-Yi; Wang, Ya; Chow, Kin-Hung

    2015-11-09

    Increasing consumption of nitrofurantoin (NIT) for treatment of acute uncomplicated urinary tract infections (UTI) highlights the need to monitor emerging NIT resistance mechanisms. This study investigated the molecular epidemiology of the multidrug-resistant efflux gene oqxAB and its contribution to nitrofurantoin resistance by using Escherichia coli isolates originating from patients with UTI (n = 205; collected in 2004 to 2013) and food-producing animals (n = 136; collected in 2012 to 2013) in Hong Kong. The oqxAB gene was highly prevalent among NIT-intermediate (11.5% to 45.5%) and -resistant (39.2% to 65.5%) isolates but rare (0% to 1.7%) among NIT-susceptible (NIT-S) isolates. In our isolates, the oqxAB gene was associated with IS26 and was carried by plasmids of diverse replicon types. Multilocus sequence typing revealed that the clones of oqxAB-positive E. coli were diverse. The combination of oqxAB and nfsA mutations was found to be sufficient for high-level NIT resistance. Curing of oqxAB-carrying plasmids from 20 NIT-intermediate/resistant UTI isolates markedly reduced the geometric mean MIC of NIT from 168.9 μg/ml to 34.3 μg/ml. In the plasmid-cured variants, 20% (1/5) of isolates with nfsA mutations were NIT-S, while 80% (12/15) of isolates without nfsA mutations were NIT-S (P = 0.015). The presence of plasmid-based oqxAB increased the mutation prevention concentration of NIT from 128 μg/ml to 256 μg/ml and facilitated the development of clinically important levels of nitrofurantoin resistance. In conclusion, plasmid-mediated oqxAB is an important nitrofurantoin resistance mechanism. There is a great need to monitor the dissemination of this transferable multidrug-resistant efflux pump.

  16. A peripheral endocannabinoid mechanism contributes to glucocorticoid-mediated metabolic syndrome

    PubMed Central

    Bowles, Nicole P.; Karatsoreos, Ilia N.; Li, Xiaosong; Vemuri, V. Kiran; Wood, Jodi-Anne; Li, Zhiying; Tamashiro, Kellie L. K.; Schwartz, Gary J.; Makriyannis, Alexandros M.; Kunos, George; Hillard, Cecilia J.; McEwen, Bruce S.; Hill, Matthew N.

    2015-01-01

    Glucocorticoids are known to promote the development of metabolic syndrome through the modulation of both feeding pathways and metabolic processes; however, the precise mechanisms of these effects are not well-understood. Recent evidence shows that glucocorticoids possess the ability to increase endocannabinoid signaling, which is known to regulate appetite, energy balance, and metabolic processes through both central and peripheral pathways. The aim of this study was to determine the role of endocannabinoid signaling in glucocorticoid-mediated obesity and metabolic syndrome. Using a mouse model of excess corticosterone exposure, we found that the ability of glucocorticoids to increase adiposity, weight gain, hormonal dysregulation, hepatic steatosis, and dyslipidemia was reduced or reversed in mice lacking the cannabinoid CB1 receptor as well as mice treated with the global CB1 receptor antagonist AM251. Similarly, a neutral, peripherally restricted CB1 receptor antagonist (AM6545) was able to attenuate the metabolic phenotype caused by chronic corticosterone, suggesting a peripheral mechanism for these effects. Biochemical analyses showed that chronic excess glucocorticoid exposure produced a significant increase in hepatic and circulating levels of the endocannabinoid anandamide, whereas no effect was observed in the hypothalamus. To test the role of the liver, specific and exclusive deletion of hepatic CB1 receptor resulted in a rescue of the dyslipidemic effects of glucocorticoid exposure, while not affecting the obesity phenotype or the elevations in insulin and leptin. Together, these data indicate that glucocorticoids recruit peripheral endocannabinoid signaling to promote metabolic dysregulation, with hepatic endocannabinoid signaling being especially important for changes in lipid metabolism. PMID:25535367

  17. The antinociceptive effect of mirtazapine in mice is mediated through serotonergic, noradrenergic and opioid mechanisms.

    PubMed

    Schreiber, Shaul; Rigai, Tova; Katz, Yeshayahu; Pick, Chaim G

    2002-09-30

    The antinociceptive effects of the noradrenergic and specific serotonergic antidepressant (NaSSA) drug mirtazapine and its interaction with various opioid receptor subtypes were evaluated in mice with a hotplate analgesicmeter. Mirtazapine elicited an antinociceptive effect in a dose-dependent manner following doses from 1 to 7.5mg/kg. As the mirtazapine dose increased beyond 10mg/kg latencies returned to baseline, yielding a biphasic dose-response curve. The effect of opioid, adrenergic, and serotonergic receptor antagonists was examined as to their ability to block mirtazapine antinociception. Mirtazapine (at 10mg/kg)-induced antinociception was significantly inhibited by naloxone, nor-BNI, and naltrindole, but neither by beta-FNA nor by naloxonazine, implying the involvement of kappa(1)- and delta-opioid mechanisms. When adrenergic and serotonergic antagonists were used, both metergoline and yohimbine, decreased antinociception elicited by mirtazapine, implying a combined serotonergic and noradrenergic mechanism of antinociception. When mirtazapine was administered together with various agonists of the opioid receptor subtypes, it significantly potentiated antinociception mediated only by kappa(3)-opioid receptor subtypes. Summing up these results we conclude that the antinociceptive effect of mirtazapine is mainly influenced by the kappa(3)-opioid receptor subtype combined with both serotonergic and noradrenergic receptors. These results suggest a potential use of mirtazapine in the management of some pain syndromes, and raise questions regarding a possible indirect opioid-dependence induced by mirtazapine. However, further research is needed in order to establish both the exact clinical indications and the effective doses of mirtazapine when prescribed for pain. PMID:12372565

  18. Using hierarchical linear growth models to evaluate protective mechanisms that mediate science achievement

    NASA Astrophysics Data System (ADS)

    von Secker, Clare Elaine

    The study of students at risk is a major topic of science education policy and discussion. Much research has focused on describing conditions and problems associated with the statistical risk of low science achievement among individuals who are members of groups characterized by problems such as poverty and social disadvantage. But outcomes attributed to these factors do not explain the nature and extent of mechanisms that account for differences in performance among individuals at risk. There is ample theoretical and empirical evidence that demographic differences should be conceptualized as social contexts, or collections of variables, that alter the psychological significance and social demands of life events, and affect subsequent relationships between risk and resilience. The hierarchical linear growth models used in this dissertation provide greater specification of the role of social context and the protective effects of attitude, expectations, parenting practices, peer influences, and learning opportunities on science achievement. While the individual influences of these protective factors on science achievement were small, their cumulative effect was substantial. Meta-analysis conducted on the effects associated with psychological and environmental processes that mediate risk mechanisms in sixteen social contexts revealed twenty-two significant differences between groups of students. Positive attitudes, high expectations, and more intense science course-taking had positive effects on achievement of all students, although these factors were not equally protective in all social contexts. In general, effects associated with authoritative parenting and peer influences were negative, regardless of social context. An evaluation comparing the performance and stability of hierarchical linear growth models with traditional repeated measures models is included as well.

  19. DNA polymerase kappa microsatellite synthesis: two distinct mechanisms of slippage-mediated errors.

    PubMed

    Baptiste, Beverly A; Eckert, Kristin A

    2012-12-01

    Microsatellite tandem repeats are frequent sites of strand slippage mutagenesis in the human genome. Microsatellite mutations often occur as insertion/deletion of a repeat motif (unit-based indels), and increase in frequency with increasing repeat length after a threshold is reached. We recently demonstrated that DNA polymerase κ (Pol κ) produces fewer unit-based indel errors within dinucleotide microsatellites than does polymerase δ. Here, we examined human Pol κ's error profile within microsatellite alleles of varying sequence composition and length, using an in vitro HSV-tk gap-filling assay. We observed that Pol κ displays relatively accurate synthesis for unit-based indels, using di- and tetranucleotide repeat templates longer than the threshold length. We observed an abrupt increase in the unit-based indel frequency when the total microsatellite length exceeds 28 nucleotides, suggesting that extended Pol κ protein-DNA interactions enhance fidelity of the enzyme when synthesizing these microsatellite alleles. In contrast, Pol κ is error-prone within the HSV-tk coding sequence, producing frequent single-base errors in a manner that is highly biased with regard to sequence context. Single-nucleotide errors are also created by Pol κ within di- and tetranucleotide repeats, independently of the microsatellite allele length and at a frequency per nucleotide similar to the frequency of single base errors within the coding sequence. These single-base errors represent the mutational signature of Pol κ, and we propose them a mechanism independent of homology-stabilized slippage. Pol κ's dual fidelity nature provides a unique research tool to explore the distinct mechanisms of slippage-mediated mutagenesis. PMID:22965905

  20. Plasmid-Mediated OqxAB Is an Important Mechanism for Nitrofurantoin Resistance in Escherichia coli

    PubMed Central

    Ng, Ka-Ying; Lo, Wai-U; Law, Pierra Y.; Lai, Eileen Ling-Yi; Wang, Ya; Chow, Kin-Hung

    2015-01-01

    Increasing consumption of nitrofurantoin (NIT) for treatment of acute uncomplicated urinary tract infections (UTI) highlights the need to monitor emerging NIT resistance mechanisms. This study investigated the molecular epidemiology of the multidrug-resistant efflux gene oqxAB and its contribution to nitrofurantoin resistance by using Escherichia coli isolates originating from patients with UTI (n = 205; collected in 2004 to 2013) and food-producing animals (n = 136; collected in 2012 to 2013) in Hong Kong. The oqxAB gene was highly prevalent among NIT-intermediate (11.5% to 45.5%) and -resistant (39.2% to 65.5%) isolates but rare (0% to 1.7%) among NIT-susceptible (NIT-S) isolates. In our isolates, the oqxAB gene was associated with IS26 and was carried by plasmids of diverse replicon types. Multilocus sequence typing revealed that the clones of oqxAB-positive E. coli were diverse. The combination of oqxAB and nfsA mutations was found to be sufficient for high-level NIT resistance. Curing of oqxAB-carrying plasmids from 20 NIT-intermediate/resistant UTI isolates markedly reduced the geometric mean MIC of NIT from 168.9 μg/ml to 34.3 μg/ml. In the plasmid-cured variants, 20% (1/5) of isolates with nfsA mutations were NIT-S, while 80% (12/15) of isolates without nfsA mutations were NIT-S (P = 0.015). The presence of plasmid-based oqxAB increased the mutation prevention concentration of NIT from 128 μg/ml to 256 μg/ml and facilitated the development of clinically important levels of nitrofurantoin resistance. In conclusion, plasmid-mediated oqxAB is an important nitrofurantoin resistance mechanism. There is a great need to monitor the dissemination of this transferable multidrug-resistant efflux pump. PMID:26552976

  1. The Molecular Mechanism of Ethylene-Mediated Root Hair Development Induced by Phosphate Starvation.

    PubMed

    Song, Li; Yu, Haopeng; Dong, Jinsong; Che, Ximing; Jiao, Yuling; Liu, Dong

    2016-07-01

    Enhanced root hair production, which increases the root surface area for nutrient uptake, is a typical adaptive response of plants to phosphate (Pi) starvation. Although previous studies have shown that ethylene plays an important role in root hair development induced by Pi starvation, the underlying molecular mechanism is not understood. In this work, we characterized an Arabidopsis mutant, hps5, that displays constitutive ethylene responses and increased sensitivity to Pi starvation due to a mutation in the ethylene receptor ERS1. hps5 accumulates high levels of EIN3 protein, a key transcription factor involved in the ethylene signaling pathway, under both Pi sufficiency and deficiency. Pi starvation also increases the accumulation of EIN3 protein. Combined molecular, genetic, and genomic analyses identified a group of genes that affect root hair development by regulating cell wall modifications. The expression of these genes is induced by Pi starvation and is enhanced in the EIN3-overexpressing line. In contrast, the induction of these genes by Pi starvation is suppressed in ein3 and ein3eil1 mutants. EIN3 protein can directly bind to the promoter of these genes, some of which are also the immediate targets of RSL4, a key transcription factor that regulates root hair development. Based on these results, we propose that under normal growth conditions, the level of ethylene is low in root cells; a group of key transcription factors, including RSL4 and its homologs, trigger the transcription of their target genes to promote root hair development; Pi starvation increases the levels of the protein EIN3, which directly binds to the promoters of the genes targeted by RSL4 and its homologs and further increase their transcription, resulting in the enhanced production of root hairs. This model not only explains how ethylene mediates root hair responses to Pi starvation, but may provide a general mechanism for how ethylene regulates root hair development under both stress

  2. The Molecular Mechanism of Ethylene-Mediated Root Hair Development Induced by Phosphate Starvation

    PubMed Central

    Song, Li; Yu, Haopeng; Dong, Jinsong; Liu, Dong

    2016-01-01

    Enhanced root hair production, which increases the root surface area for nutrient uptake, is a typical adaptive response of plants to phosphate (Pi) starvation. Although previous studies have shown that ethylene plays an important role in root hair development induced by Pi starvation, the underlying molecular mechanism is not understood. In this work, we characterized an Arabidopsis mutant, hps5, that displays constitutive ethylene responses and increased sensitivity to Pi starvation due to a mutation in the ethylene receptor ERS1. hps5 accumulates high levels of EIN3 protein, a key transcription factor involved in the ethylene signaling pathway, under both Pi sufficiency and deficiency. Pi starvation also increases the accumulation of EIN3 protein. Combined molecular, genetic, and genomic analyses identified a group of genes that affect root hair development by regulating cell wall modifications. The expression of these genes is induced by Pi starvation and is enhanced in the EIN3-overexpressing line. In contrast, the induction of these genes by Pi starvation is suppressed in ein3 and ein3eil1 mutants. EIN3 protein can directly bind to the promoter of these genes, some of which are also the immediate targets of RSL4, a key transcription factor that regulates root hair development. Based on these results, we propose that under normal growth conditions, the level of ethylene is low in root cells; a group of key transcription factors, including RSL4 and its homologs, trigger the transcription of their target genes to promote root hair development; Pi starvation increases the levels of the protein EIN3, which directly binds to the promoters of the genes targeted by RSL4 and its homologs and further increase their transcription, resulting in the enhanced production of root hairs. This model not only explains how ethylene mediates root hair responses to Pi starvation, but may provide a general mechanism for how ethylene regulates root hair development under both stress

  3. Therapeutic targeting of myeloid-derived suppressor cells involves a novel mechanism mediated by clusterin

    PubMed Central

    Zhou, Junmin; Donatelli, Sarah S.; Gilvary, Danielle L.; Tejera, Melba M.; Eksioglu, Erika A.; Chen, Xianghong; Coppola, Domenico; Wei, Sheng; Djeu, Julie Y.

    2016-01-01

    Myeloid-derived suppressor cells (MDSCs) constitute a key checkpoint that impedes tumor immunity against cancer. Chemotherapeutic intervention of MDSCs has gained ground as a strategy for cancer therapy but its mechanism remains obscure.We report here a unique mechanism by which monocytic (M)-MDSCs are spared, allowing them to polarize towards M1 macrophages for reactivation of immunity against breast cancer. We first demonstrated that curcumin, like docetaxel (DTX), can selectively target CD11b+Ly6G+Ly6Clow granulocytic (G)-MDSCs, sparing CD11b+Ly6G−Ly6Chigh M-MDSCs, with reduced tumor burden in 4T1-Neu tumor-bearing mice. Curcumin treatment polarized surviving M-MDSCs toward CCR7+ Dectin-1−M1 cells, accompanied by IFN-γ production and cytolytic function in T cells. Selective M-MDSC chemoresistence to curcumin and DTX was mediated by secretory/cytoplasmic clusterin (sCLU). sCLU functions by trapping Bax from mitochondrial translocation, preventing the apoptotic cascade. Importantly, sCLU was only found in M-MDSCs but not in G-MDSCs. Knockdown of sCLU in M-MDSCs and RAW264.7 macrophages was found to reverse their natural chemoresistance. Clinically, breast cancer patients possess sCLU expression only in mature CD68+ macrophages but not in immature CD33+ immunosuppressive myeloid cells infiltrating the tumors. We thus made the seminal discovery that sCLU expression in M-MDSCs accounts for positive immunomodulation by chemotherapeutic agents. PMID:27405665

  4. Benzodiazepine receptor ligand influences on acquisition: suggestion of an endogenous modulatory mechanism mediated by benzodiazepine receptors.

    PubMed

    Izquierdo, I; Pereira, M E; Medina, J H

    1990-07-01

    In rats, pretraining ip administration of the central benzodiazepine receptor antagonist, flumazenil (5.0 mg/kg), or of the inverse agonist, n-butyl-beta-carboline-3-carboxylate (BCCB) (0.2 or 0.5 mg/kg), facilitated retention of a step-down inhibitory avoidance task; the central agonists, clonazepam and diazepam (0.4 or 1.0 mg/kg), had an opposite effect, and the peripheral agonist, 4'-chlordiazepam (1.25 or 6.25 mg/kg), was without effect. Pre- but not post-training flumazenil (2.0 mg/kg) blocked the effect of BCCB (0.5 mg/kg), clonazepam (1.0 mg/kg), or diazepam (1.0 mg/kg) given also pretraining. The post-training administration of all of these drugs had no effect on retention of the avoidance task. Flumazenil (5.0 mg/kg) and BCCB (0.5 mg/kg), given before training, enhanced retention test performance of habituation to a buzzer but not of habituation to an open field. In the three tasks studied, none of the drugs used had any appreciable effect on training session parameters. These results suggest that there is an endogenous mechanism mediated by benzodiazepine agonists, sensitive to inverse agonists, that normally down-regulates acquisition of certain behaviors; this mechanism becomes activated only when the tasks involve or occur with a certain degree of stress or anxiety (i.e., inhibitory avoidance or habituation to the buzzer) and not in less stressful or anxiogenic tasks (i.e., habituation to an open field).

  5. CHOLINERGIC NEURONS OF THE BASAL FOREBRAIN MEDIATE BIOCHEMICAL AND ELECTROPHYSIOLOGICAL MECHANISMS UNDERLYING SLEEP HOMEOSTASIS

    PubMed Central

    Kalinchuk, Anna V.; Porkka-Heiskanen, Tarja; McCarley, Robert W.; Basheer, Radhika

    2015-01-01

    The tight coordination of biochemical and electrophysiological mechanisms underlies the homeostatic sleep pressure (HSP) produced by sleep deprivation (SD). We have reported that during SD the levels of inducible nitric oxide synthase (iNOS), extracellular nitric oxide (NO), adenosine [AD]ex, lactate [Lac]ex and pyruvate [Pyr]ex increase in the basal forebrain (BF). However, it is not clear whether all of them contribute to HSP leading to increased electroencephalogram (EEG) delta activity during non-rapid eye movement (NREM) recovery sleep (RS) following SD. Previously, we showed that NREM delta increase evident during RS depends on the presence of BF cholinergic (ChBF) neurons. Here, we investigated the role of ChBF cells in coordination of biochemical and EEG changes seen during SD and RS in the rat. Increases in low theta power (5–7Hz), but not high theta (7–9Hz), during SD correlated with the increase in NREM delta power during RS, and with the changes in nitrate/nitrite [NOx]ex and [AD]ex. Lesions of ChBF cells using IgG 192-saporin prevented increases in [NOx]ex, [AD]ex and low theta activity, during SD, but did not prevent increases in [Lac]ex and [Pyr]ex. Infusion of NO donor DETA NONOate into the saporin-treated BF failed to increase NREM RS and delta power, suggesting ChBF cells are important for mediating NO homeostatic effects. Finally, SD-induced iNOS was mostly expressed in ChBF cells, and the intensity of iNOS induction correlated with the increase in low theta activity. Together, our data indicate ChBF cells are important in regulating the biochemical and EEG mechanisms that contribute to HSP. PMID:25369989

  6. Structurally novel steroidal spirooxindole by241 potently inhibits tumor growth mainly through ROS-mediated mechanisms

    PubMed Central

    Shi, Xiao-Jing; Yu, Bin; Wang, Jun-Wei; Qi, Ping-Ping; Tang, Kai; Huang, Xin; Liu, Hong-Min

    2016-01-01

    Cancer cells always have increased ROS levels, thus making them more vulnerable to persistent endogenous oxidative stress. The biochemical difference between cancer and normal cells could be exploited to achieve selective cancer cell killing by exogenous ROS-producing agents. Herein we described a structurally novel steroidal spirooxindole by241 and its anticancer efficacy. By241 exhibited potent inhibition against human cancer cells and less toxic to normal cells. By241 concentration-dependently induced apoptosis of MGC-803 and EC9706 cells, accompanied with the mitochondrial dysfunction and increased ROS levels. NAC can completely restore the decreased cell viability of MGC-803 cells caused by by241, suggesting ROS-mediated mechanisms. The expression levels of proteins involved in the mitochondrion-related pathways were detected, showing increased expression of proapoptotic proteins and decreased expression of anti-apoptotic proteins, and activation of caspases-9/-3, but without activating caspase-8 expression. Pretreatment with Z-VAD-FMK partially rescued by241-induced apoptosis of MGC-803 cells. Additionally, by241 inhibited mTOR, activated p53 and its downstream proteins, cleaved MDM2 and PI3K/AKT as well as NF-κB signaling pathway. In vivo experiments showed that by241 did not have significant acute oral toxicity and exerted good anticancer efficacy against MGC-803 bearing mice models. Therefore, by241 may serve as a lead for further development for cancer therapy. PMID:27527552

  7. MutS mediates heteroduplex loop formation by a translocation mechanism.

    PubMed Central

    Allen, D J; Makhov, A; Grilley, M; Taylor, J; Thresher, R; Modrich, P; Griffith, J D

    1997-01-01

    Interaction of Escherichia coli MutS and MutL with heteroduplex DNA has been visualized by electron microscopy. In a reaction dependent on ATP hydrolysis, complexes between a MutS dimer and a DNA heteroduplex are converted to protein-stabilized, alpha-shaped loop structures with the mismatch in most cases located within the DNA loop. Loop formation depends on ATP hydrolysis and loop size increases linearly with time at a rate of 370 base pairs/min in phosphate buffer and about 10,000 base pairs/min in the HEPES buffer used for repair assay. These observations suggest a translocation mechanism in which a MutS dimer bound to a mismatch subsequently leaves this site by ATP-dependent tracking or unidimensional movement that is in most cases bidirectional from the mispair. In view of the bidirectional capability of the methyl-directed pathway, this reaction may play a role in determination of heteroduplex orientation. The rate of MutS-mediated DNA loop growth is enhanced by MutL, and when both proteins are present, both are found at the base of alpha-loop structures, and both can remain associated with excision intermediates produced in later stages of the reaction. PMID:9250691

  8. MECHANISMS OF NITROSAMINE–MEDIATED NEURODEGENERATION: POTENTIAL RELEVANCE TO SPORADIC ALZHEIMER’S DISEASE

    PubMed Central

    de la Monte, Suzanne M.; Tong, Ming

    2015-01-01

    Background Streptozotocin (STZ) is a nitrosamine-related compound that causes Alzheimer disease (AD)-type neurodegeneration with cognitive impairment, brain insulin resistance, and brain insulin deficiency. Nitrosamines and STZ mediate their adverse effects by causing DNA damage, oxidative stress, lipid peroxidation, pro-inflammatory cytokine activation, and cell death, all of which occur in AD. Objective We tested the hypothesis that exposure to N-nitrosodiethylamine (NDEA), which is widely present in processed/preserved foods, causes AD-type molecular and biochemical abnormalities in central nervous system (CNS) neurons. Results NDEA treatment of cultured post-mitotic rat CNS neurons (48 h) produced dose-dependent impairments in ATP production and mitochondrial function, and increased levels of 8-hydroxy-2′-deoxyguanosine (8-OHdG), 4-hydroxy-2-nonenal (HNE), phospho-Tau, amyloid precursor protein-amyloid beta (AβPP-Aβ), and ubiquitin immunoreactivity. These effects were associated with decreased expression of the insulin, IGF-I, and IGF-II receptors, and choline acetyltransferase. Conclusions Nitrosamine exposure causes neurodegeneration with a number of molecular and biochemical features of AD including impairments in energy metabolism, insulin/IGF signaling mechanisms, and acetylcholine homeostasis, together with increased levels of oxidative stress, DNA damage and AβPP-Aβ immunoreactivity. These results suggest that environmental exposures and food contaminants may play critical roles in the pathogenesis of sporadic AD. PMID:19542621

  9. Simple fast noninvasive technique for measuring brachial wall mechanics during flow mediated vasodilatation analysis

    NASA Astrophysics Data System (ADS)

    Mahmoud, Ahmed M.; Stapleton, Phoebe A.; Frisbee, Jefferson C.; D'Audiffret, Alexandre; Mukdadi, Osama M.

    2009-02-01

    Measurement of flow-mediated vasodilatation (FMD) in brachial and other conduit arteries has become a common method to asses the status of endothelial function in vivo. In spite of the direct relationship between the arterial wall multi-component strains and FMD responses, direct measurement of wall strain tensor due to FMD has not yet been reported in the literature. In this work, a noninvasive direct ultrasound-based strain tensor measuring (STM) technique is presented to assess changes in the mechanical parameters of the vascular wall during FMD. The STM technique utilizes only sequences of B-mode ultrasound images, and starts with segmenting a region of interest within the artery and providing the acquisition parameters. Then a block matching technique is employed to measure the frame to frame local velocities. Displacements, diameter change, multi-component strain tensor and strain rates are then calculated by integrating or differentiating velocity components. The accuracy of the STM algorithm was assessed using a phantom study, and was further validated using in vivo data from human subjects. Results indicate the validity and versatility of the STM algorithm, and describe how parameters other than the diameter change are sensitive to pre- and post-occlusion, which can then be used for accurate assessment of atherosclerosis.

  10. Long-term neurobehavioural impact of the postnatal environment in rats: manipulations, effects and mediating mechanisms.

    PubMed

    Pryce, Christopher R; Feldon, Joram

    2003-01-01

    The major characteristics of the postnatal environment of the rat pup are its mother and littermates. The pup, which is poorly developed at birth, matures rapidly in this environment, and regulates the behaviour and physiology of the dam and littermates, as well as vice versa. The study of the impact of the rat's postnatal environment on its long-term neurobehavioural development is of fundamental importance. In fact, it is one of the major examples--at the interface of the biological, social and medical sciences--of animal models for the study of the interaction between the environment and the genome in both the acute and chronic regulation of the phenotype. Specific experimental manipulations of the rat postnatal environment have been demonstrated to exert robust and marked effects on neurobiological, physiological and behavioural phenotypes in adulthood. In the present review we present some of the major findings, including some original data, and discuss what these existing data can tell us about the long-term neurobehavioural effects of the postnatal environment in rats, the external and internal mechanisms that mediate these effects, and the most appropriate directions for future basic and applied research in this area. PMID:12732223

  11. The contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using diamond anodes.

    PubMed

    Bensalah, Nasr; Dbira, Sondos; Bedoui, Ahmed

    2016-07-01

    In this work, the contribution of mediated oxidation mechanisms in the electrolytic degradation of cyanuric acid using boron-doped diamond (BDD) anodes was investigated in different electrolytes. A complete mineralization of cyanuric acid was obtained in NaCl; however lower degrees of mineralization of 70% and 40% were obtained in Na2SO4 and NaClO4, respectively. This can be explained by the nature of the oxidants electrogenerated in each electrolyte. It is clear that the contribution of active chlorine (Cl2, HClO, ClO(-)) electrogenerated from oxidation of chlorides on BDD is much more important in the electrolytic degradation of cyanuric acid than the persulfate and hydroxyl radicals produced by electro-oxidation of sulfate and water on BDD anodes. This could be explained by the high affinity of active chlorine towards nitrogen compounds. No organic intermediates were detected during the electrolytic degradation of cyanuric acid in any the electrolytes, which can be explained by their immediate depletion by hydroxyl radicals produced on the BDD surface. Nitrates and ammonium were the final products of electrolytic degradation of cyanuric acid on BDD anodes in all electrolytes. In addition, small amounts of chloramines were formed in the chloride medium. Low current density (≤10mA/cm(2)) and neutral medium (pH in the range 6-9) should be used for high efficiency electrolytic degradation and negligible formation of hazardous chlorate and perchlorate. PMID:27372125

  12. A Leptin-Mediated Central Mechanism in Analgesia-Enhanced Opioid Reward in Rats

    PubMed Central

    Lim, Grewo; Kim, Hyangin; McCabe, Michael F.; Chou, Chiu-Wen; Wang, Shuxing; Chen, Lucy L.; Marota, John J.A.; Blood, Anne; Breiter, Hans C.

    2014-01-01

    Opioid analgesics are commonly used in chronic pain management despite a potential risk of rewarding. However, it remains unclear whether opioid analgesia would enhance the opioid rewarding effect thereby contributing to opioid rewarding. Utilizing a rat paradigm of conditioned place preference (CPP) combined with ankle monoarthritis as a condition of persistent nociception, we showed that analgesia induced by either morphine or the nonsteroid anti-inflammatory drug ibuprofen increased CPP scores in arthritic rats, suggesting that analgesia itself had a rewarding effect. However, arthritic rats exhibited a significantly higher CPP score in response to morphine than ibuprofen. Thus, the rewarding effect of morphine was enhanced in the presence of persistent nociception, producing a phenomenon of analgesia-enhanced opioid reward. At the cellular level, administration of morphine activated a cascade of leptin expression, glial activation, and dopamine receptor upregulation in the nucleus accumbens (NAc), while administration of ibuprofen decreased glial activation with no effect on leptin expression in the NAc. Furthermore, the morphine rewarding effect was blocked in leptin deficient ob/ob mice or by neutralizing leptin or interleukin-1β in the NAc without diminishing morphine analgesia. The data indicate that systemic opioid can activate a leptin-mediated central mechanism in the NAc that led to the enhanced opioid rewarding effect. These findings provide evidence for an interaction between opioid analgesia and opioid rewarding, which may have implications in clinical opioid dose escalation in chronic pain management. PMID:25031415

  13. Mechanisms Mediating Environmental Chemical-Induced Endocrine Disruption in the Adrenal Gland

    PubMed Central

    Martinez-Arguelles, Daniel B.; Papadopoulos, Vassilios

    2015-01-01

    Humans are continuously exposed to hundreds of man-made chemicals that pollute the environment in addition to multiple therapeutic drug treatments administered throughout life. Some of these chemicals, known as endocrine disruptors (EDs), mimic endogenous signals, thereby altering gene expression, influencing development, and promoting disease. Although EDs are eventually removed from the market or replaced with safer alternatives, new evidence suggests that early-life exposure leaves a fingerprint on the epigenome, which may increase the risk of disease later in life. Epigenetic changes occurring in early life in response to environmental toxicants have been shown to affect behavior, increase cancer risk, and modify the physiology of the cardiovascular system. Thus, exposure to an ED or combination of EDs may represent a first hit to the epigenome. Only limited information is available regarding the effect of ED exposure on adrenal function. The adrenal gland controls the stress response, blood pressure, and electrolyte homeostasis. This endocrine organ therefore has an important role in physiology and is a sensitive target of EDs. We review herein the effect of ED exposure on the adrenal gland with particular focus on in utero exposure to the plasticizer di(2-ethylehyl) phthalate. We discuss the challenges associated with identifying the mechanism mediating the epigenetic origins of disease and availability of biomarkers that may identify individual or population risks. PMID:25788893

  14. TRF2-Mediated Control of Telomere DNA Topology as a Mechanism for Chromosome-End Protection.

    PubMed

    Benarroch-Popivker, Delphine; Pisano, Sabrina; Mendez-Bermudez, Aaron; Lototska, Liudmyla; Kaur, Parminder; Bauwens, Serge; Djerbi, Nadir; Latrick, Chrysa M; Fraisier, Vincent; Pei, Bei; Gay, Alexandre; Jaune, Emilie; Foucher, Kevin; Cherfils-Vicini, Julien; Aeby, Eric; Miron, Simona; Londoño-Vallejo, Arturo; Ye, Jing; Le Du, Marie-Hélène; Wang, Hong; Gilson, Eric; Giraud-Panis, Marie-Josèphe

    2016-01-21

    The shelterin proteins protect telomeres against activation of the DNA damage checkpoints and recombinational repair. We show here that a dimer of the shelterin subunit TRF2 wraps ∼ 90 bp of DNA through several lysine and arginine residues localized around its homodimerization domain. The expression of a wrapping-deficient TRF2 mutant, named Top-less, alters telomeric DNA topology, decreases the number of terminal loops (t-loops), and triggers the ATM checkpoint, while still protecting telomeres against non-homologous end joining (NHEJ). In Top-less cells, the protection against NHEJ is alleviated if the expression of the TRF2-interacting protein RAP1 is reduced. We conclude that a distinctive topological state of telomeric DNA, controlled by the TRF2-dependent DNA wrapping and linked to t-loop formation, inhibits both ATM activation and NHEJ. The presence of RAP1 at telomeres appears as a backup mechanism to prevent NHEJ when topology-mediated telomere protection is impaired.

  15. Bed rest decreases mechanically induced myofiber wounding and consequent wound-mediated FGF release.

    PubMed

    Clarke, M S; Bamman, M M; Feeback, D L

    1998-08-01

    Using a terrestrial model of spaceflight (i.e., bed rest), we investigated the amount of myofiber wounding and fibroblast growth factor (FGF) release that occurs during unloading. Myofiber wounding was determined by serum levels of the creatine kinase MM (CKMM) isoform before and after bed rest. Serum levels of both acidic FGF (aFGF) and basic FGF were also determined. A second group of subjects was treated in an identical fashion except that they underwent a resistive exercise program during bed rest. Bed rest alone caused significant (P < 0.05; n = 7) reductions in post-bed-rest serum levels of both CKMM and aFGF, which were paralleled by a significant (P < 0.05; n = 7) decrease in myofiber size. In contrast, bed rest plus resistive exercise resulted in significant (P < 0.05; n = 7) increases in post-bed-rest serum levels of both CKMM and aFGF, which were paralleled by inhibition of the atrophic response. These results suggest that mechanically induced, myofiber wound-mediated FGF release may play an important role in the etiology of unloading-induced skeletal muscle atrophy. PMID:9688737

  16. Investigation on the mechanism of aminosilane-mediated bonding of thermoplastics and poly(dimethylsiloxane).

    PubMed

    Sunkara, Vijaya; Cho, Yoon-Kyoung

    2012-12-01

    A possible mechanism for the aminosilane-mediated room-temperature (RT) bonding of thermoplastics and poly(dimethylsiloxane) (PDMS) is presented. The plasma-activated thermoplastic or PDMS substrates were modified with alkoxy silanes having different organo functional groups, and their bonding characteristics were studied. Manual peeling tests revealed that strong bonding was realized only when the silane had a free amino group and at least two alkoxy groups on the silicon. Silanization was carried out in both aqueous and anhydrous conditions; bonding occurred readily at RT in the former case, but a longer incubation time or a higher temperature was needed for the latter. The presence of the silane on the surface was confirmed by contact-angle measurements and UV spectrophotometric, attenuated total reflectance infrared spectroscopic (ATR-IR) and X-ray photoelectron spectroscopic (XPS) analyses. In the case where the aminosilane was deposited from aqueous solution, the amino functionality of the silane-catalyzed siloxane bond formation between the silanol on the modified thermoplastic surface and the silanol of the plasma-activated PDMS. In the case of anhydrous phase deposition, the aminosilane first catalyzed the hydrolysis of the ethoxy groups on the silicon, and then, catalyzed the condensation between the silanol groups of both materials. Shelf life tests of the modified thermoplastics showed that the aminosilane was stable over 2 weeks, and that bonding occurred at RT when the substrates were soaked in water before bonding.

  17. Mechanisms of PECAM-1-mediated cytoprotection and implications for cancer cell survival.

    PubMed

    Bergom, Carmen; Gao, Cunji; Newman, Peter J

    2005-10-01

    Defects in apoptotic pathways can promote cancer development and cause cancers to become resistant to chemotherapy. The cell adhesion and signaling molecule PECAM-1 has been shown to potently suppress apoptosis in a variety of cellular systems. PECAM-1 expression has been reported on a variety of human malignancies-especially hematopoietic and vascular cell cancers-but the significance of this expression has not been fully explored. The ability of PECAM-1 to inhibit apoptosis makes it an attractive candidate as a molecule that may promote cancer development and/or confer resistance to chemotherapeutic treatment. The exact mechanisms by which PECAM-1 mediates its cytoprotection have not been fully defined, but its anti-apoptotic effects have been shown to require both homophilic binding and intracellular signaling via its immunoreceptor tyrosine-based inhibitory motif (ITIM) domains. In this review, we will discuss the data regarding PECAM-1's anti-apoptotic effects and ways in which this cytoprotection may be clinically relevant to the development and/or treatment of hematologic malignancies that express this vascular cell-specific surface molecule. PMID:16194886

  18. Overcoming NS1-mediated immune antagonism involves both interferon-dependent and independent mechanisms.

    PubMed

    Thakar, Juilee; Schmid, Sonja; Duke, Jamie L; García-Sastre, Adolfo; Kleinstein, Steven H

    2013-11-01

    To ensure survival, our immune system must overcome the action of pathogen-encoded immune antagonists, such as influenza A nonstructural protein-1 (NS1). NS1 subverts the host interferon (IFN) response at multiple levels and blocks the induction of IFN-β, a critical antiviral cytokine. This immune antagonism can be overcome in some cases. It has been shown that IFN-β is upregulated by 48 h in the lungs of wild-type C57BL/6 mice infected with influenza A. In contrast, it is shown here that IFNB1 continues to be repressed in IFNAR1(-/-) IL28Rα(-/-) mice, which are deficient in Type-I and III IFN signaling, implying induction of IFNB1 depends on effective IFN signaling. Despite the complete lack of IFN signaling in this system, some IFN stimulated genes (ISGs) were induced following infection with a Flu strain lacking NS1. While the expression of these viral stress-inducible genes (VSIGs) was initially repressed following infection with wild-type Flu, many of these genes became upregulated by 48 h postinfection. These results demonstrate the existence of IFN-independent mechanisms that can overcome NS1-mediated immune antagonism of VSIGs.

  19. Progesterone stimulates respiration through a central nervous system steroid receptor-mediated mechanism in cat.

    PubMed

    Bayliss, D A; Millhorn, D E; Gallman, E A; Cidlowski, J A

    1987-11-01

    We have examined the effect on respiration of the steroid hormone progesterone, administered either intravenously or directly into the medulla oblongata in anesthetized and paralyzed male and female cats. The carotid sinus and vagus nerves were cut, and end-tidal PCO2 and temperature were kept constant with servo-controllers. Phrenic nerve activity was used to quantitate central respiratory activity. Repeated doses of progesterone (from 0.1 to 2.0 micrograms/kg, cumulative) caused a sustained (greater than 45 min) facilitation of phrenic nerve activity in female and male cats; however, the response was much more variable in females. Progesterone injected into the region of nucleus tractus solitarii, a respiratory-related area in the medulla oblongata, also caused a prolonged stimulation of respiration. Progesterone administration at high concentration by both routes also caused a substantial hypotension. Identical i.v. doses of other classes of steroid hormones (17 beta-estradiol, testosterone, and cortisol) did not elicit the same respiratory effect. Pretreatment with RU 486, a progesterone-receptor antagonist, blocked the facilitatory effect of progesterone. We conclude that progesterone acts centrally through a steroid receptor-mediated mechanism to facilitate respiration. PMID:3478727

  20. Overcoming NS1-Mediated Immune Antagonism Involves Both Interferon-Dependent and Independent Mechanisms

    PubMed Central

    Thakar, Juilee; Schmid, Sonja; Duke, Jamie L.; García-Sastre, Adolfo

    2013-01-01

    To ensure survival, our immune system must overcome the action of pathogen-encoded immune antagonists, such as influenza A nonstructural protein-1 (NS1). NS1 subverts the host interferon (IFN) response at multiple levels and blocks the induction of IFN-β, a critical antiviral cytokine. This immune antagonism can be overcome in some cases. It has been shown that IFN-β is upregulated by 48 h in the lungs of wild-type C57BL/6 mice infected with influenza A. In contrast, it is shown here that IFNB1 continues to be repressed in IFNAR1−/− IL28Rα−/− mice, which are deficient in Type-I and III IFN signaling, implying induction of IFNB1 depends on effective IFN signaling. Despite the complete lack of IFN signaling in this system, some IFN stimulated genes (ISGs) were induced following infection with a Flu strain lacking NS1. While the expression of these viral stress-inducible genes (VSIGs) was initially repressed following infection with wild-type Flu, many of these genes became upregulated by 48 h postinfection. These results demonstrate the existence of IFN-independent mechanisms that can overcome NS1-mediated immune antagonism of VSIGs. PMID:23772952

  1. Sugar-mediated chitosan/poly(ethylene glycol)-beta-dicalcium pyrophosphate composite: mechanical and microstructural properties.

    PubMed

    Wang, Jian-Wen; Hon, Min-Hsiung

    2003-02-01

    The microstructural and mechanical properties of sugar-mediated chitosan/poly(ethylene glycol)-based scaffolds and composites, which are composed of beta-dicalcium pyrophosphate (beta-DCP) and sugar-mediated scaffolds, were investigated. All of the scaffolds were prepared by various freeze-drying protocols. The differences in the freeze-drying process of the sugar-mediated chitosan/poly(ethylene glycol) scaffold for three types of sugar (sucrose, glucose, and D-fructose) were determined by scanning electron microscopic observation, water retention, density, and porosity analyses. The sugar-mediated scaffolds prepared by scheme I of the freeze-drying process show large pores, poorly connective interlayers, and disintegrated inner structures, different from the small pores and well-connective channel structures as shown in the scheme II freeze-drying process. The key factors for controlling pore structure and size in the scheme I freeze-drying process were formulation and composition, but for the scheme II freeze-drying process, the key factor was freeze protocol. The composite scaffolds were macroporous, and the microstructure changed considerably with added beta-DCP content. The incorporation of beta-DCP granules caused a significant enhancement of compressive modulus and yield strength. The increased mechanical strength may be attributable not only to the physical complexation between the sugar-mediated scaffold and beta-DCP, but also the chemical reaction to apatite formed on the cell wall.

  2. Effect of intraoperative infusion of ketamine on remifentanil-induced hyperalgesia

    PubMed Central

    Choi, Eunji; Park, Hahck Soo; Lee, Guie Yong; Kim, Youn Jin; Baik, Hee-Jung

    2015-01-01

    Background Opioid induced hyperalgesia (OIH) is related with high opioid dosage, a long duration of opioid administration, and abrupt discontinuation of infused opioids in anesthetic settings. Ketamine is known to attenuate OIH efficiently, but methods of administration and methods to quantify and assess a decrease in OIH vary. We demonstrated the existence of remifentanil-induced hyperalgesia and investigated the ability of ketamine to attenuate OIH. Methods Seventy-five patients undergoing laparoscopic gynecologic surgery under remifentanil-based anesthesia were assigned to one of the following groups: (1) group RL (remifentanil 0.05 µg/kg/min), (2) group RH (remifentanil 0.3 µg/kg/min), or (3) group KRH (remifentanil 0.3 µg/kg/min + ketamine 0.5 mg/kg bolus with 5 µg/kg/min infusion intraoperatively). Desflurane was administered for maintenance of anesthesia to target bispectral index scores (40-60) and hemodynamic parameters (heart rate and blood pressure < ± 20% of baseline values). All parameters related to OIH and its attenuation induced by ketamine were investigated. Results There was no significant difference among the three groups related to demographic and anesthetic parameters except the end-tidal concentration of desflurane. Additional analgesic consumption, numerical rating scale scores at 6 and 24 h, and cumulative fentanyl dose were significantly higher in group RH than in the other two groups. The value difference of the Touch-Test sensory evaluation was significantly higher negative in group RH than in the other two groups. Conclusions Remifentanil-induced hyperalgesia is significantly attenuated by intraoperative bolus and infusion of ketamine. Ketamine also decreased tactile sensitization, as measured by Touch-Test sensory evaluation. PMID:26495058

  3. Resveratrol attenuates inflammatory hyperalgesia by inhibiting glial activation in mice spinal cords.

    PubMed

    Wang, Lin-Lin; Shi, Dong-Ling; Gu, Hui-Yao; Zheng, Ming-Zhi; Hu, Jue; Song, Xing-Hui; Shen, Yue-Liang; Chen, Ying-Ying

    2016-05-01

    The present study aimed to investigate the effect of resveratrol on inflammatory pain. Mice were injected intraperitoneally with lipopolysaccharide (LPS) for 5 consecutive days to induce subacute systemic inflammation. Acetic acid‑induced writhing tests and tail‑flick tests were performed following the final LPS injection. Glial fibrillary acidic protein (GFAP; an astrocyte‑specific activation marker), ionized calcium binding adapter molecule 1 (Iba‑1; a microglia‑specific activation marker) and sirtuin 1 (SIRT1) protein expression levels were detected using immunohistochemistry analysis or western blotting. Following administration of LPS for 5 days, the number of writhes increased and the tail‑flick latency decreased. Resveratrol (10 or 20 mg/kg) partly inhibited LPS‑induced hyperalgesia and prevented the increase in tumor necrosis factor‑α and interleukin 6 levels induced by LPS. LPS injection reduced the SIRT1 protein expression and increased the number of GFAP‑positive and Iba‑1‑positive cells in the spinal cord. Resveratrol increased the SIRT1 protein expression levels and decreased the number of GFAP‑positive and Iba‑1‑positive cells in LPS‑treated mice. The protective effect of resveratrol was partly blocked by a selective SIRT1 inhibitor, EX‑257. Results from the present study suggest that subacute treatment with LPS induced the activation of glial cells and hyperalgesia. Resveratrol was demonstrated to inhibit the activation of glial cells and attenuate inflammatory hyperalgesia in a SIRT1‑dependent manner.

  4. Withania somnifera root extract prolongs analgesia and suppresses hyperalgesia in mice treated with morphine.

    PubMed

    Orrù, Alessandro; Marchese, Giorgio; Casu, Gianluca; Casu, Maria Antonietta; Kasture, Sanjay; Cottiglia, Filippo; Acquas, Elio; Mascia, Maria Paola; Anzani, Nicola; Ruiu, Stefania

    2014-04-15

    Previous studies demonstrated that Withania somnifera Dunal (WS), a safe medicinal plant, prevents the development of tolerance to the analgesic effect of morphine. In the present study, we investigated whether WS extract (WSE) (100 mg/kg, i.p.) may also modulate the analgesic effect induced by acute morphine administration (2.5, 5, 10 mg/kg, s.c.) in the tail-flick and in the hot plate tests, and if it may prevent the development of 2.5 mg/kg morphine-induced rebound hyperalgesia in the low intensity tail-flick test. Further, to characterize the receptor(s) involved in these effects, we studied, by receptor-binding assay, the affinity of WSE for opioid (μ, δ, k), cannabinoid (CB1, CB2), glutamatergic (NMDA), GABAergic (GABAA, GABAB), serotoninergic (5HT2A) and adrenergic (α2) receptors. The results demonstrated that (i) WSE alone failed to alter basal nociceptive threshold in both tests, (ii) WSE pre-treatment significantly protracted the antinociceptive effect induced by 5 and 10 mg/kg of morphine only in tail-flick test, (iii) WSE pre-treatment prevented morphine-induced hyperalgesia in the low intensity tail-flick test, and (iv) WSE exhibited a high affinity for the GABAA and moderate affinity for GABAB, NMDA and δ opioid receptors. WSE prolongs morphine-induced analgesia and suppresses the development of morphine-induced rebound hyperalgesia probably through involvement of GABAA, GABAB, NMDA and δ opioid receptors. This study suggests the therapeutic potential of WSE as a valuable adjuvant agent in opioid-sparing therapies.

  5. Antagonists of toll like receptor 4 maybe a new strategy to counteract opioid-induced hyperalgesia and opioid tolerance.

    PubMed

    Li, Qian

    2012-12-01

    Long term opioid treatment results in hyperalgesia and tolerance, which is a troublesome phenomenon in clinic application. Recent studies have revealed a critical role of toll-like receptor 4 (TLR4) in the neuropathological process of opioid-induced hyperalgesia and tolerance. TLR4 is predominantly expressed by microglial cells and is a key modulator in the activation of the innate immune system. Activation of TLR4 may initiate the activation of microglia and hence a number of neurotransmitters and neuromodulators that could enhance neuronal excitability are released. Blockade of TLR4 activation by its antagonists alleviate neuropathic pain. We hypothesized that opioid antagonists such as naloxone and naltrexone, which were also demonstrated to be TLR4 antagonist, may have clinic application value in attenuation of opioid-induced hyperalgesia and tolerance.

  6. [PROPHYLAXIS OF POSTOPERATIVE HYPERALGESIA, BASED ON MORPHOLOGICAL SUBSTANTIATION OF THE ANALGESIA METHOD].

    PubMed

    Dmytriyev, D V; Konoplytskyi, V S

    2016-03-01

    The investigation was conducted in 20 children, operated on for abdominal oncological diseases in a 2010-2015 yrs period, using various methods of analgesia. While application of a constant infusion of high doses of phentanyl--1-4 MKr/(kg x h) in perioperative period the occurrence of the opiate-induced hyperalgesia is possible with the accompanied morphological changes in intestinal wall; in anesthesia of a transverse abdominal muscle (a TAP-blockade) and combined spinal epidural analgesia such changes were not observed. PMID:27514091

  7. [MORPHOLOGICAL CHANGES OF SKIN IN OPERATIVE WOUND IN SYNDROME OF OPIOID-INDUCED HYPERALGESIA].

    PubMed

    Dmytriyev, D V; Konoplytskyi, V S

    2015-10-01

    Morphological changes of skin in region of operative wound were investigated. There was established, that while application of fentanyl in high doses, using constant infusion for anesthesia in early postoperative period in children, operated for abdominal cavity tumors, the opioid-induced hyperalgesia occurrence is possible, what is accompanied by morphological changes in skin around operative wound, necrosis in centre of focus, pronounced perifocal reactive changes in a kind of significant inflammation and essential disorder of microcirculation with formation of small neural fibers on the 14th day. Pronounced fibrosis of derma, formation of big quantity of collagen fibers with edema, stratification.

  8. Mechanisms of ATP-mediated vasodilation in humans: modest role for nitric oxide and vasodilating prostaglandins

    PubMed Central

    Crecelius, Anne R.; Kirby, Brett S.; Richards, Jennifer C.; Garcia, Leora J.; Voyles, Wyatt F.; Larson, Dennis G.; Luckasen, Gary J.

    2011-01-01

    ATP is an endothelium-dependent vasodilator, and findings regarding the underlying signaling mechanisms are equivocal. We sought to determine the independent and interactive roles of nitric oxide (NO) and vasodilating prostaglandins (PGs) in ATP-mediated vasodilation in young, healthy humans and determine whether any potential role was dependent on ATP dose or the timing of inhibition. In protocol 1 (n = 18), a dose-response curve to intrabrachial infusion of ATP was performed before and after both single and combined inhibition of NO synthase [NG-monomethyl-l-arginine (l-NMMA)] and cyclooxygenase (ketorolac). Forearm blood flow (FBF) was measured via venous occlusion plethysmography and forearm vascular conductance (FVC) was calculated. In this protocol, neither individual nor combined NO/PG inhibition had any effect on the vasodilatory response (P = 0.22–0.99). In protocol 2 (n = 16), we determined whether any possible contribution of both NO and PGs to ATP vasodilation was greater at low vs. high doses of ATP and whether inhibition during steady-state infusion of the respective dose of ATP impacted the dilation. FBF in this protocol was measured via Doppler ultrasound. In protocol 2, infusion of low (n = 8)- and high-dose (n = 8) ATP for 5 min evoked a significant increase in FVC above baseline (low = 198 ± 24%; high = 706 ± 79%). Infusion of l-NMMA and ketorolac together reduced steady-state FVC during both low- and high-dose ATP (P < 0.05), and in a subsequent trial with continuous NO/PG blockade, the vasodilator response from baseline to 5 min of steady-state infusion was similarly reduced for both low (ΔFVC = −31 ± 11%)- and high-dose ATP (ΔFVC −25 ± 11%; P = 0.70 low vs. high dose). Collectively, our findings indicate a potential modest role for NO and PGs in the vasodilatory response to exogenous ATP in the human forearm that does not appear to be dose or timing dependent; however, this is dependent on the method for assessing forearm vascular

  9. Feline immunodeficiency virus envelope glycoprotein mediates apoptosis in activated PBMC by a mechanism dependent on gp41 function

    SciTech Connect

    Garg, Himanshu; Joshi, Anjali; Tompkins, Wayne A. . E-mail: Wayne_Tompkins@ncsu.edu

    2004-12-20

    Feline Immunodeficiency Virus (FIV) is a lentivirus that causes immunodeficiency in cats, which parallels HIV-1-induced immunodeficiency in humans. It has been established that HIV envelope (Env) glycoprotein mediates T cell loss via a mechanism that requires CXCR4 binding. The Env glycoprotein of FIV, similar to HIV, requires CXCR4 binding for viral entry, as well as inducing membrane fusion leading to syncytia formation. However, the role of FIV Env in T cell loss and the molecular mechanisms governing this process have not been elucidated. We studied the role of Env glycoprotein in FIV-mediated T cell apoptosis in an in vitro model. Our studies demonstrate that membrane-expressed FIV Env induces apoptosis in activated feline peripheral blood mononuclear cells (PBMC) by a mechanism that requires CXCR4 binding, as the process was inhibited by CXCR4 antagonist AMD3100 in a dose-dependent manner. Interestingly, studies regarding the role of CD134, the recently identified primary receptor of FIV, suggest that binding to CD134 may not be important for induction of apoptosis in PBMC. However, inhibiting Env-mediated fusion post CXCR4 binding by FIV gp41-specific fusion inhibitor also inhibited apoptosis. Under similar conditions, a fusion-defective gp41 mutant was unable to induce apoptosis in activated PBMC. Our findings are the first report suggesting the potential of FIV Env to mediate apoptosis in bystander cells by a process that is dependent on gp41 function.

  10. Intrathecal Urocortin I in the spinal cord as a murine model of stress hormone-induced musculoskeletal and tactile hyperalgesia

    PubMed Central

    Larson, Alice A.; Nunez, Myra G.; Kissel, Casey L.; Kovács, Katalin J.

    2015-01-01

    Stress is antinociceptive in some models of pain but enhances musculoskeletal nociceptive responses in mice and muscle pain in patients with fibromyalgia syndrome. To test the hypothesis that urocortins are stress hormones that are sufficient to enhance tactile and musculoskeletal hyperalgesia, we measured von Frey fiber sensitivity and grip force after injection of corticotrophin releasing factor (CRF), urocortin I and urocortin II in mice. Urocortin I (a CRF1 and CRF2 receptor ligand) produced hyperalgesia in both assays when injected intrathecally (i.t.) but not intracerebroventricularly (i.c.v.), and only at a large dose when injected peripherally, suggesting a spinal action. Morphine inhibited urocortin I-induced changes in nociceptive responses in a dose-related fashion, confirming that changes in behavior reflect hyperalgesia rather than weakness. No tolerance developed to the effect of urocortin I (i.t.) when injected repeatedly, consistent with a potential to enhance pain chronically. Tactile hyperalgesia was inhibited by NBI-35965, a CRF1 receptor antagonist, but not astressin 2B, a CRF2 receptor antagonist. However, while urocortin I-induced decreases in grip force were not observed when coadministered i.t. with either NBI-35965 or astressin 2B, they were even more sensitive to inhibition by astressin, a nonselective CRF receptor antagonist. Together these data indicate that urocortin I acts at CRF receptors in the mouse spinal cord to elicit a reproducible and persistent tactile (von Frey) and musculoskeletal (grip force) hyperalgesia. Urocortin I-induced hyperalgesia may serve as a screen for drugs that alleviate painful conditions that are exacerbated by stress. PMID:26332847

  11. Psychological mechanism linking abusive supervision and compulsory citizenship behavior: a moderated mediation study.

    PubMed

    Zhao, Hongdan; Peng, Zhenglong; Han, Yong; Sheard, Geoff; Hudson, Alan

    2013-01-01

    This study seeks to examine the effect of abusive supervision on the "dark side" of organizational citizenship behavior (OCB) and, specifically, compulsory citizenship behavior (CCB). The study focuses on the mediating role of psychological safety underpinning the relationship between abusive supervision and CCB, and the moderating role of Chinese traditionality in influencing the mediation. The authors tested the model with data of 434 dyads (employee-coworker pairs) in a large Chinese service company. Results indicated that psychological safety fully mediated the relationship between abusive supervision and CCB. The authors also found that Chinese traditionality moderated the strength of the mediated relationship between abusive supervision and CCB via psychological safety, such that the mediated relationship is weaker under high Chinese traditionality than under low Chinese traditionality. The article also discusses the implications, limitations, and future research directions.

  12. Psychological mechanism linking abusive supervision and compulsory citizenship behavior: a moderated mediation study.

    PubMed

    Zhao, Hongdan; Peng, Zhenglong; Han, Yong; Sheard, Geoff; Hudson, Alan

    2013-01-01

    This study seeks to examine the effect of abusive supervision on the "dark side" of organizational citizenship behavior (OCB) and, specifically, compulsory citizenship behavior (CCB). The study focuses on the mediating role of psychological safety underpinning the relationship between abusive supervision and CCB, and the moderating role of Chinese traditionality in influencing the mediation. The authors tested the model with data of 434 dyads (employee-coworker pairs) in a large Chinese service company. Results indicated that psychological safety fully mediated the relationship between abusive supervision and CCB. The authors also found that Chinese traditionality moderated the strength of the mediated relationship between abusive supervision and CCB via psychological safety, such that the mediated relationship is weaker under high Chinese traditionality than under low Chinese traditionality. The article also discusses the implications, limitations, and future research directions. PMID:23469477

  13. Development of a peptidomimetic antagonist of neuropeptide FF receptors for the prevention of opioid-induced hyperalgesia.

    PubMed

    Bihel, Frédéric; Humbert, Jean-Paul; Schneider, Séverine; Bertin, Isabelle; Wagner, Patrick; Schmitt, Martine; Laboureyras, Emilie; Petit-Demoulière, Benoît; Schneider, Elodie; Mollereau, Catherine; Simonnet, Guy; Simonin, Frédéric; Bourguignon, Jean-Jacques

    2015-03-18

    Through the development of a new class of unnatural ornithine derivatives as bioisosteres of arginine, we have designed an orally active peptidomimetic antagonist of neuropeptide FF receptors (NPFFR). Systemic low-dose administration of this compound to rats blocked opioid-induced hyperalgesia, without any apparent side-effects. Interestingly, we also observed that this compound potentiated opioid-induced analgesia. This unnatural ornithine derivative provides a novel therapeutic approach for both improving analgesia and reducing hyperalgesia induced by opioids in patients being treated for chronic pain.

  14. Alcohol consumption enhances antiretroviral painful peripheral neuropathy by mitochondrial mechanisms

    PubMed Central

    Ferrari, Luiz F.; Levine, Jon D.

    2010-01-01

    A major dose-limiting side effect of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) chemotherapies, such as the nucleoside reverse transcriptase inhibitors (NRTIs), is a small-fiber painful peripheral neuropathy, mediated by its mitochondrial toxicity. Co-morbid conditions may also contribute to this dose-limiting effect of HIV/AIDS treatment. Alcohol abuse, which alone also produces painful neuropathy, is one of the most important co-morbid risk factors for peripheral neuropathy in patients with HIV/AIDS. Despite the prevalence of this problem and its serious impact on the quality of life and continued therapy in HIV/AIDS patients, the mechanisms by which alcohol abuse exacerbates highly active antiretroviral therapy (HAART)-induced neuropathic pain has not been demonstrated. In this study, performed in rats, we investigated the cellular mechanism by which consumed alcohol impacts antiretroviral-induced neuropathic pain. NRTI 2',3'-dideoxycytidine (ddC) (50 mg/kg) neuropathy was mitochondrial dependent and PKCε independent, and alcohol-induced painful neuropathy, PKCε dependent and mitochondrial independent. At low doses, ddC (5 mg/kg) and alcohol (6.5% ethanol diet for one week), which alone do not affect nociception, together produce profound mechanical hyperalgesia. This hyperalgesia is mitochondrial dependent but PKCε independent. These experiments, which provide the first model for studying the impact of co-morbidity in painful neuropathy, support the clinical impression that alcohol consumption enhances HIV/AIDS therapy neuropathy, and provide evidence for a role of mitochondrial mechanisms underlying this interaction. PMID:20726883

  15. Mechanisms of a novel anticancer therapeutic strategy involving atmospheric pressure plasma-mediated apoptosis and DNA strand break formation.

    PubMed

    Chung, Woo-Hyun

    2016-01-01

    Atmospheric pressure plasma has been developed for a variety of biomedical applications due to its chemically reactive components. Recently, the plasma has emerged as a promising novel cancer therapy based on its ability to selectively ablate cancer cells while leaving normal cells essentially unaffected. The therapeutic effect of plasma is attributed to intracellular generation of reactive oxygen/nitrogen species (ROS/RNS) leading to mitochondria-mediated apoptosis and to activation of the DNA damage checkpoint signaling pathway via severe DNA strand break formation. However, the biochemical mechanisms responsible for appropriate activation of these physiological events and which pathway is more crucial for plasma-mediated cytotoxicity have not been clarified. Understanding the molecular link between ROS/RNS-mediated apoptosis and DNA damage-involved chromosome instability is critical for the development of more efficacious therapeutic strategies for selective killing of diverse cancer cells.

  16. A simple retinal mechanism contributes to perceptual interactions between rod- and cone-mediated responses in primates.

    PubMed

    Grimes, William N; Graves, Logan R; Summers, Mathew T; Rieke, Fred

    2015-01-01

    Visual perception across a broad range of light levels is shaped by interactions between rod- and cone-mediated signals. Because responses of retinal ganglion cells, the output cells of the retina, depend on signals from both rod and cone photoreceptors, interactions occurring in retinal circuits provide an opportunity to link the mechanistic operation of parallel pathways and perception. Here we show that rod- and cone-mediated responses interact nonlinearly to control the responses of primate retinal ganglion cells; these nonlinear interactions, surprisingly, were asymmetric, with rod responses strongly suppressing subsequent cone responses but not vice-versa. Human psychophysical experiments revealed a similar perceptual asymmetry. Nonlinear interactions in the retinal output cells were well-predicted by linear summation of kinetically-distinct rod- and cone-mediated signals followed by a synaptic nonlinearity. These experiments thus reveal how a simple mechanism controlling interactions between parallel pathways shapes circuit output and perception. PMID:26098124

  17. Chronic elevation of IL-1β induces diuresis via a cyclooxygenase 2-mediated mechanism.

    PubMed

    Boesen, E I

    2013-07-15

    Chronic renal inflammation is an increasingly recognized phenomenon in multiple disease states, but the impact of specific cytokines on renal function is unclear. Previously, we found that 14-day interleukin-1β (IL-1β) infusion increased urine flow in mice. To determine the mechanism by which this occurs, the current study tested the possible involvement of three classical prodiuretic pathways. Chronic IL-1β infusion significantly increased urine flow (6.5 ± 1 ml/day at day 14 vs. 2.3 ± 0.3 ml/day in vehicle group; P < 0.05) and expression of cyclooxygenase (COX)-2, all three nitric oxide synthase (NOS) isoforms, and endothelin (ET)-1 in the kidney (P < 0.05 in all cases). Urinary prostaglandin E metabolite (PGEM) excretion was also significantly increased at day 14 of IL-1β infusion (1.21 ± 0.26 vs. 0.29 ± 0.06 ng/day in vehicle-infused mice; P = 0.001). The selective COX-2 inhibitor celecoxib markedly attenuated urinary PGEM excretion and abolished the diuretic response to chronic IL-1β infusion. In contrast, deletion of NOS3, or inhibition of NOS1 with L-VNIO, did not blunt the diuretic effect of IL-1β, nor did pharmacological blockade of endothelin ETA and ETB receptors with A-182086. Consistent with a primary effect on water transport, IL-1β infusion markedly reduced inner medullary aquaporin-2 expression (P < 0.05) and did not alter urinary Na⁺ or K⁺ excretion. These data indicate a critical role for COX-2 in mediating the effects of chronic IL-1β elevation on the kidney.

  18. Conclusive evidence on the mechanism of the rhodium-mediated decyanative borylation.

    PubMed

    Esteruelas, Miguel A; Oliván, Montserrat; Vélez, Andrea

    2015-09-30

    The stoichiometric reactions proposed in the mechanism of the rhodium-mediated decyanative borylation have been performed and all relevant intermediates isolated and characterized including their X-ray structures. Complex RhCl{xant(P(i)Pr2)2} (1, xant(P(i)Pr2)2 = 9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene) reacts with bis(pinacolato)diboron (B2pin2), in benzene, to give the rhodium(III) derivative RhHCl(Bpin){xant(P(i)Pr2)2} (4) and PhBpin. The reaction involves the oxidative addition of B2pin2 to 1 to give RhCl(Bpin)2{xant(P(i)Pr2)2}, which eliminates ClBpin generating Rh(Bpin){xant(P(i)Pr2)2} (2). The reaction of the latter with the solvent yields PhBpin and the monohydride RhH{xant(P(i)Pr2)2} (6), which adds the eliminated ClBpin. Complex 4 and its catecholboryl counterpart RhHCl(Bcat){xant(P(i)Pr2)2} (7) have also been obtained by oxidative addition of HBR2 to 1. Complex 2 is the promoter of the decyanative borylation. Thus, benzonitrile and 4-(trifluoromethyl)benzonitrile insert into the Rh-B bond of 2 to form Rh{C(R-C6H4)═NBpin}{xant(P(i)Pr2)2} (R = H (8), p-CF3 (9)), which evolve into the aryl derivatives RhPh{xant(P(i)Pr2)2} (3) and Rh(p-CF3-C6H4){xant(P(i)Pr2)2} (10), as a result of the extrusion of CNBpin. The reactions of 3 and 10 with B2pin2 yield the arylBpin products and regenerate 2.

  19. Ligand-Specific Transcriptional Mechanisms Underlie Aryl Hydrocarbon Receptor-Mediated Developmental Toxicity of Oxygenated PAHs

    PubMed Central

    Goodale, B. C.; La Du, J.; Tilton, S. C.; Sullivan, C. M.; Bisson, W. H.; Waters, K. M.; Tanguay, R. L.

    2015-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are priority environmental contaminants that exhibit mutagenic, carcinogenic, proinflammatory, and teratogenic properties. Oxygen-substituted PAHs (OPAHs) are formed during combustion processes and via phototoxidation and biological degradation of parent (unsubstituted) PAHs. Despite their prevalence both in contaminated industrial sites and in urban air, OPAH mechanisms of action in biological systems are relatively understudied. Like parent PAHs, OPAHs exert structure-dependent mutagenic activities and activation of the aryl hydrocarbon receptor (AHR) and cytochrome p450 metabolic pathway. Four-ring OPAHs 1,9-benz-10-anthrone (BEZO) and benz(a)anthracene-7,12-dione (7,12-B[a]AQ) cause morphological aberrations and induce markers of oxidative stress in developing zebrafish with similar potency, but only 7,12-B[a]AQ induces robust Cyp1a protein expression. We investigated the role of the AHR in mediating the toxicity of BEZO and 7,12-B[a]AQ, and found that knockdown of AHR2 rescued developmental effects caused by both compounds. Using RNA-seq and molecular docking, we identified transcriptional responses that precede developmental toxicity induced via differential interaction with AHR2. Redox-homeostasis genes were affected similarly by these OPAHs, while 7,12-B[a]AQ preferentially activated phase 1 metabolism and BEZO uniquely decreased visual system genes. Analysis of biological functions and upstream regulators suggests that BEZO is a weak AHR agonist, but interacts with other transcriptional regulators to cause developmental toxicity in an AHR-dependent manner. Identifying ligand-dependent AHR interactions and signaling pathways is essential for understanding toxicity of this class of environmentally relevant compounds. PMID:26141390

  20. Ciprofloxacin mediates cancer stem cell phenotypes in lung cancer cells through caveolin-1-dependent mechanism.

    PubMed

    Phiboonchaiyanan, Preeyaporn Plaimee; Kiratipaiboon, Chayanin; Chanvorachote, Pithi

    2016-04-25

    Cancer stem cells (CSCs), a subpopulation of cancer cells with high aggressive behaviors, have been identified in many types of cancer including lung cancer as one of the key mediators driving cancer progression and metastasis. Here, we have reported for the first time that ciprofloxacin (CIP), a widely used anti-microbial drug, has a potentiating effect on CSC-like features in human non-small cell lung cancer (NSCLC) cells. CIP treatment promoted CSC-like phenotypes, including enhanced anchorage-independent growth and spheroid formation. The known lung CSC markers: CD133, CD44, ABCG2 and ALDH1A1 were found to be significantly increased, while the factors involving in epithelial to mesenchymal transition (EMT): Slug and Snail, were depleted. Also, self-renewal transcription factors Oct-4 and Nanog were found to be up-regulated in CIP-treated cells. The treatment of CIP on CSC-rich populations obtained from secondary spheroids resulted in the further increase of CSC markers. In addition, we have proven that the mechanistic insight of the CIP induced stemness is through Caveolin-1 (Cav-1)-dependent mechanism. The specific suppression of Cav-1 by stably transfected Cav-1 shRNA plasmid dramatically reduced the effect of CIP on CSC markers as well as the CIP-induced spheroid formation ability. Cav-1 was shown to activate protein kinase B (Akt) and extracellular signal-regulated kinase (ERK) pathways in CSC-rich population; however, such an effect was rarely found in the main lung cancer cells population. These findings reveal a novel effect of CIP in positively regulating CSCs in lung cancer cells via the activation of Cav-1, Akt and ERK, and may provoke the awareness of appropriate therapeutic strategy in cancer patients.

  1. Persistent polar depletion of stratospheric ozone and emergent mechanisms of ultraviolet radiation-mediated health dysregulation.

    PubMed

    Dugo, Mark A; Han, Fengxiang; Tchounwou, Paul B

    2012-01-01

    Year 2011 noted the first definable ozone "hole" in the Arctic region, serving as an indicator to the continued threat of dangerous ultraviolet radiation (UVR) exposure caused by the deterioration of stratospheric ozone in the northern hemisphere. Despite mandates of the Montreal Protocol to phase out the production of ozone-depleting chemicals (ODCs), the relative stability of ODCs validates popular notions of persistent stratospheric ozone for several decades. Moreover, increased UVR exposure through stratospheric ozone depletion is occurring within a larger context of physiologic stress and climate change across the biosphere. In this review, we provide commentaries on stratospheric ozone depletion with relative comparisons between the well-known Antarctic ozone hole and the newly defined ozone hole in the Arctic. Compared with the Antarctic region, the increased UVR exposure in the Northern Hemisphere poses a threat to denser human populations across North America, Europe, and Asia. In this context, we discuss emerging targets of UVR exposure that can potentially offset normal biologic rhythms in terms of taxonomically conserved photoperiod-dependent seasonal signaling and entrainment of circadian clocks. Consequences of seasonal shifts during critical life history stages can alter fitness and condition, whereas circadian disruption is increasingly becoming associated as a causal link to increased carcinogenesis. We further review the significance of genomic alterations via UVR-induced modulations of phase I and II transcription factors located in skin cells, the aryl hydrocarbon receptor (AhR), and the nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2), with emphasis on mechanism that can lead to metabolic shifts and cancer. Although concern for adverse health consequences due to increased UVR exposure are longstanding, recent advances in biochemical research suggest that AhR and Nrf2 transcriptional regulators are likely targets for UVR-mediated

  2. Mechanisms underlying the postexercise baroreceptor‐mediated suppression of heat loss

    PubMed Central

    McGinn, Ryan; Paull, Gabrielle; Meade, Robert D.; Fujii, Naoto; Kenny, Glen P.

    2014-01-01

    Abstract Reports indicate that postexercise heat loss is modulated by baroreceptor input; however, the mechanisms remain unknown. We examined the time‐dependent involvement of adenosine receptors, noradrenergic transmitters, and nitric oxide (NO) in modulating baroreceptor‐mediated changes in postexercise heat loss. Eight males performed two 15‐min cycling bouts (85% VO2max) each followed by a 45‐min recovery in the heat (35°C). Lower body positive (LBPP), negative (LBNP), or no (Control) pressure were applied in three separate sessions during the final 30‐min of each recovery. Four microdialysis fibres in the forearm skin were perfused with: (1) lactated Ringer's (Ringer's); (2) 4 mmol·L−1 Theophylline (inhibits adenosine receptors); (3) 10 mmol·L−1 Bretylium (inhibits noradrenergic transmitter release); or (4) 10 mmol·L−1 l‐NAME (inhibits NO synthase). We measured cutaneous vascular conductance (CVC; percentage of maximum) calculated as perfusion units divided by mean arterial pressure, and local sweat rate. Compared to Control, LBPP did not influence CVC at l‐NAME, Theophylline or Bretylium during either recovery (P >0.07); however, CVC at Ringer's was increased by ~5‐8% throughout 30 min of LBPP during Recovery 1 (all P <0.02). In fact, CVC at Ringer's was similar to Theophylline and Bretylium during LBPP. Conversely, LBNP reduced CVC at all microdialysis sites by ~7–10% in the last 15 min of Recovery 2 (all P <0.05). Local sweat rate was similar at all treatment sites as a function of pressure condition (P >0.10). We show that baroreceptor input modulates postexercise CVC to some extent via adenosine receptors, noradrenergic vasoconstriction, and NO whereas no influence was observed for postexercise sweating. PMID:25293599

  3. Molecular mechanism of Hoxd13-mediated congenital malformations in rat embryos

    PubMed Central

    Wang, Fenglan; Du, Mingzhen; Wang, Ruiling; Zhou, Juekun; Zhang, Wei; Li, Huixue

    2015-01-01

    Objective: To investigate the molecular mechanism of Hoxd13-mediated congenital malformations in rat embryos. Methods: SD female rats were mated with male rats in a 1:1 mating scheme. Thirty pregnant female rats were randomly divided into three groups: the control group receiving a normal diet, the model group receiving a vitamin A-deficient diet, and the treatment group receiving a vitamin A-deficient diet supplemented with pcDNA-Hoxd13. The expression of Hoxd13 mRNA and protein in normal embryonic tissue and congenital malformations was determined by RT-PCR and Western blot analysis. At day 20, rats were dissected, and the fetal weight, body and tail length, and the number of live births, absorbed fetus, and stillbirth in each group were recorded. Wnt and Slim1 expression was detected by RT-PCR and Western blot analysis. β-catenin and c-myc expression was also quantified by Western blot analysis. Results: The expression of Hoxd13 mRNA and protein in congenital malformations was significantly lower compared with normal embryonic tissue (P<0.01). The administration of exogenous Hoxd13 in the treatment group markedly increased the fetal weight, body and tail length (P<0.05), improved the embryonic survival rate, and reduced the embryonic resorption rate and stillbirth rate (P<0.05). Exogenous Hoxd13 markedly promoted the expression of Wnt2, Wnt5a, Wnt7b and Slim1 protein and mRNA (P<0.01), and the expression of β-catenin and c-myc protein in congenital malformations (P<0.01). Conclusion: Hoxd13 expression was decreased in rat embryos with congenital malformations. The administration of exogenous Hoxd13 alleviated fetal malformation probably through stimulation of Slim1 expression and Wnt/β-catenin signaling pathway. PMID:26884828

  4. CDI Systems Are Stably Maintained by a Cell-Contact Mediated Surveillance Mechanism

    PubMed Central

    Chen, Annette J.; Leung, Nicole Y.; Hayes, Christopher S.; Low, David A.

    2016-01-01

    Contact-dependent growth inhibition (CDI) systems are widespread amongst Gram-negative bacteria where they play important roles in inter-cellular competition and biofilm formation. CDI+ bacteria use cell-surface CdiA proteins to bind neighboring bacteria and deliver C-terminal toxin domains. CDI+ cells also express CdiI immunity proteins that specifically neutralize toxins delivered from adjacent siblings. Genomic analyses indicate that cdi loci are commonly found on plasmids and genomic islands, suggesting that these Type 5 secretion systems are spread through horizontal gene transfer. Here, we examine whether CDI toxin and immunity activities serve to stabilize mobile genetic elements using a minimal F plasmid that fails to partition properly during cell division. This F plasmid is lost from Escherichia coli populations within 50 cell generations, but is maintained in ~60% of the cells after 100 generations when the plasmid carries the cdi gene cluster from E. coli strain EC93. By contrast, the ccdAB "plasmid addiction" module normally found on F exerts only a modest stabilizing effect. cdi-dependent plasmid stabilization requires the BamA receptor for CdiA, suggesting that plasmid-free daughter cells are inhibited by siblings that retain the CDI+ plasmid. In support of this model, the CDI+ F plasmid is lost rapidly from cells that carry an additional cdiI immunity gene on a separate plasmid. These results indicate that plasmid stabilization occurs through elimination of non-immune cells arising in the population via plasmid loss. Thus, genetic stabilization reflects a strong selection for immunity to CDI. After long-term passage for more than 300 generations, CDI+ plasmids acquire mutations that increase copy number and result in 100% carriage in the population. Together, these results show that CDI stabilizes genetic elements through a toxin-mediated surveillance mechanism in which cells that lose the CDI system are detected and eliminated by their siblings

  5. Ligand-specific transcriptional mechanisms underlie aryl hydrocarbon receptor-mediated developmental toxicity of oxygenated PAHs

    SciTech Connect

    Goodale, B. C.; La Du, J.; Tilton, S. C.; Sullivan, C. M.; Bisson, W. H.; Waters, K. M.; Tanguay, R. L.

    2015-07-03

    Polycyclic aromatic hydrocarbons (PAHs) are priority environmental contaminants that exhibit mutagenic, carcinogenic, proinflammatory, and teratogenic properties. Oxygen-substituted PAHs (OPAHs) are formed during combustion processes and via phototoxidation and biological degradation of parent (unsubstituted) PAHs. Despite their prevalence both in contaminated industrial sites and in urban air, OPAH mechanisms of action in biological systems are relatively understudied. Like parent PAHs, OPAHs exert structure-dependent mutagenic activities and activation of the aryl hydrocarbon receptor (AHR) and cytochrome p450 metabolic pathway. Four-ring OPAHs 1,9-benz-10-anthrone (BEZO) and benz(a)anthracene-7,12-dione (7,12-B[a]AQ) cause morphological aberrations and induce markers of oxidative stress in developing zebrafish with similar potency, but only 7,12-B[a]AQ induces robust Cyp1a protein expression. We investigated the role of the AHR in mediating the toxicity of BEZO and 7,12-B[a]AQ, and found that knockdown of AHR2 rescued developmental effects caused by both compounds. Using RNA-seq and molecular docking, we identified transcriptional responses that precede developmental toxicity induced via differential interaction with AHR2. Redox-homeostasis genes were affected similarly by these OPAHs, while 7,12-B[a]AQ preferentially activated phase 1 metabolism and BEZO uniquely decreased visual system genes. Analysis of biological functions and upstream regulators suggests that BEZO is a weak AHR agonist, but interacts with other transcriptional regulators to cause developmental toxicity in an AHR-dependent manner. Furthermore, identifying ligand-dependent AHR interactions and signaling pathways is essential for understanding toxicity of this class of environmentally relevant compounds.

  6. Ligand-specific transcriptional mechanisms underlie aryl hydrocarbon receptor-mediated developmental toxicity of oxygenated PAHs

    DOE PAGES

    Goodale, B. C.; Geisel School of Medicine at Dartmouth, Hanover, NH; La Du, J.; Tilton, S. C.; Pacific Northwest National Lab.; Sullivan, C. M.; Bisson, W. H.; Waters, K. M.; Tanguay, R. L.

    2015-07-03

    Polycyclic aromatic hydrocarbons (PAHs) are priority environmental contaminants that exhibit mutagenic, carcinogenic, proinflammatory, and teratogenic properties. Oxygen-substituted PAHs (OPAHs) are formed during combustion processes and via phototoxidation and biological degradation of parent (unsubstituted) PAHs. Despite their prevalence both in contaminated industrial sites and in urban air, OPAH mechanisms of action in biological systems are relatively understudied. Like parent PAHs, OPAHs exert structure-dependent mutagenic activities and activation of the aryl hydrocarbon receptor (AHR) and cytochrome p450 metabolic pathway. Four-ring OPAHs 1,9-benz-10-anthrone (BEZO) and benz(a)anthracene-7,12-dione (7,12-B[a]AQ) cause morphological aberrations and induce markers of oxidative stress in developing zebrafish with similar potency, butmore » only 7,12-B[a]AQ induces robust Cyp1a protein expression. We investigated the role of the AHR in mediating the toxicity of BEZO and 7,12-B[a]AQ, and found that knockdown of AHR2 rescued developmental effects caused by both compounds. Using RNA-seq and molecular docking, we identified transcriptional responses that precede developmental toxicity induced via differential interaction with AHR2. Redox-homeostasis genes were affected similarly by these OPAHs, while 7,12-B[a]AQ preferentially activated phase 1 metabolism and BEZO uniquely decreased visual system genes. Analysis of biological functions and upstream regulators suggests that BEZO is a weak AHR agonist, but interacts with other transcriptional regulators to cause developmental toxicity in an AHR-dependent manner. Furthermore, identifying ligand-dependent AHR interactions and signaling pathways is essential for understanding toxicity of this class of environmentally relevant compounds.« less

  7. Molecular mechanisms of hormone-mediated Müllerian duct regression: involvement of beta-catenin.

    PubMed

    Allard, S; Adin, P; Gouédard, L; di Clemente, N; Josso, N; Orgebin-Crist, M C; Picard, J Y; Xavier, F

    2000-08-01

    Regression of the Müllerian duct in the male embryo is one unequivocal effect of anti-Müllerian hormone, a glycoprotein secreted by the Sertoli cells of the testis. This hormone induces ductal epithelial regression through a paracrine mechanism originating in periductal mesenchyme. To probe the mechanisms of action of anti-Müllerian hormone, we have studied the sequence of cellular and molecular events involved in duct regression. Studies were performed in male rat embryos and in transgenic mice overexpressing or lacking anti-Müllerian hormone, both in vivo and in vitro. Anti-Müllerian hormone causes regression of the cranial part of the Müllerian duct whereas it continues to grow caudally. Our work shows that this pattern of regression is correlated with a cranial to caudal gradient of anti-Müllerian hormone receptor protein, followed by a wave of apoptosis spreading along the Müllerian duct as its progresses caudally. Apoptosis is also induced by AMH in female Müllerian duct in vitro. Furthermore, apoptotic indexes are increased in Müllerian epithelium of transgenic mice of both sexes overexpressing the human anti-Müllerian hormone gene, exhibiting a positive correlation with serum hormone concentration. Inversely, apoptosis is reduced in male anti-Müllerian hormone-deficient mice. We also show that apoptosis is a decisive but not sufficient process, and that epitheliomesenchymal transformation is an important event of Müllerian regression. The most striking result of this study is that anti-Müllerian hormone action in peri-Müllerian mesenchyme leads in vivo and in vitro to an accumulation of cytoplasmic beta-catenin. The co-localization of beta-catenin with lymphoid enhancer factor 1 in the nucleus of peri-Müllerian mesenchymal cells, demonstrated in primary culture, suggests that overexpressed beta-catenin in association with lymphoid enhancer factor 1 may alter transcription of target genes and may lead to changes in mesenchymal gene expression

  8. Mechanism of PP2A-mediated IKKβ dephosphorylation: a systems biological approach

    PubMed Central

    Witt, Johannes; Barisic, Sandra; Schumann, Eva; Allgöwer, Frank; Sawodny, Oliver; Sauter, Thomas; Kulms, Dagmar

    2009-01-01

    Background Biological effects of nuclear factor-κB (NFκB) can differ tremendously depending on the cellular context. For example, NFκB induced by interleukin-1 (IL-1) is converted from an inhibitor of death receptor induced apoptosis into a promoter of ultraviolet-B radiation (UVB)-induced apoptosis. This conversion requires prolonged NFκB activation and is facilitated by IL-1 + UVB-induced abrogation of the negative feedback loop for NFκB, involving a lack of inhibitor of κB (IκBα) protein reappearance. Permanent activation of the upstream kinase IKKβ results from UVB-induced inhibition of the catalytic subunit of Ser-Thr phosphatase PP2A (PP2Ac), leading to immediate phosphorylation and degradation of newly synthesized IκBα. Results To investigate the mechanism underlying the general PP2A-mediated tuning of IKKβ phosphorylation upon IL-1 stimulation, we have developed a strictly reduced mathematical model based on ordinary differential equations which includes the essential processes concerning the IL-1 receptor, IKKβ and PP2A. Combining experimental and modelling approaches we demonstrate that constitutively active, but not post-stimulation activated PP2A, tunes out IKKβ phosphorylation thus allowing for IκBα resynthesis in response to IL-1. Identifiability analysis and determination of confidence intervals reveal that the model allows reliable predictions regarding the dynamics of PP2A deactivation and IKKβ phosphorylation. Additionally, scenario analysis is used to scrutinize several hypotheses regarding the mode of UVB-induced PP2Ac inhibition. The model suggests that down regulation of PP2Ac activity, which results in prevention of IκBα reappearance, is not a direct UVB action but requires instrumentality. Conclusion The model developed here can be used as a reliable building block of larger NFκB models and offers comprehensive simplification potential for future modeling of NFκB signaling. It gives more insight into the newly discovered

  9. Selective neutralization of prostaglandin E2 blocks inflammation, hyperalgesia, and interleukin 6 production in vivo

    PubMed Central

    1996-01-01

    The role of prostaglandin E2 (PGE2) in the development of inflammatory symptoms and cytokine production was evaluated in vivo using a neutralizing anti-PGE2 monoclonal antibody 2B5. In carrageenan-induced paw inflammation, pretreatment of rats with 2B5 substantially prevented the development of tissue edema and hyperalgesia in affected paws. The antibody was shown to bind the majority of PGE2 produced at the inflammatory site. In adjuvant-induced arthritis, the therapeutic administration of 2B5 to arthritic rats substantially reversed edema in affected paws. Anti-PGE2 treatment also reduced paw levels of IL-6 RNA and serum IL-6 protein without modifying tumor necrosis factor RNA levels in the same tissue. In each model, the antiinflammatory efficacy of 2B5 was indistinguishable from that of the nonsteroidal antiinflammatory drug indomethacin, which blocked the production of all PGs. These results indicate that PGE2 plays a major role in tissue edema, hyperalgesia, and IL-6 production at sites of inflammation, and they suggest that selective pharmacologic modulation of PGE2 synthesis or activity may provide a useful means of mitigating the symptoms of inflammatory disease. PMID:9064348

  10. Remifentanil-acute opioid tolerance and opioid-induced hyperalgesia: a systematic review.

    PubMed

    Kim, Sang Hun; Stoicea, Nicoleta; Soghomonyan, Suren; Bergese, Sergio D

    2015-01-01

    The use of opioids may seem to be a double-edged sword; they provide straight analgesic and antihyperalgesic effects initially, but subsequently are associated with the expression of acute opioid tolerance (AOT) and opioid-induced hyperalgesia (OIH) that have been reported in experimental studies and clinical observations. It has been suggested that opioids can induce an acute tolerance and hyperalgesia in dose- and/or time-dependent manners even when used within the clinically accepted doses. Recently, remifentanil has been used for pain management in clinical anesthesia and in the intensive care units because of its rapid onset and offset. We reviewed articles analyzing AOT and/or OIH by remifentanil and focused on the following issues: (1) evidence of remifentanil inducing AOT and/or OIH and (2) importance of AOT and/or OIH in considering the reduction of remifentanil dosage or adopting preventive modulations. Twenty-four experimental and clinical studies were identified using electronic searches of MEDLINE (PubMed, Ovid, Springer, and Elsevier). However, the development of AOT and OIH by remifentanil administration remains controversial. There is no sufficient evidence to support or refute the existence of OIH in humans.

  11. Bilateral hyperalgesia to chemical stimulation of the nasal mucosa following unilateral inflammation.

    PubMed

    Mohammadian, P; Hummel, T; Loetsch, J; Kobal, G

    1997-12-01

    The aim of the present study was to investigate the bilateral sensory changes to chemical noxious stimuli in the trigeminally innervated areas following unilateral nasal inflammation. Twenty healthy volunteers took part in five experiments. Intranasal inflammation was induced by means of a constant flow of cold air (145 ml/s); temperature and humidity of the airstream were varied across experiments. For the non-inflamed (NOI) condition, air temperature was 36 degrees C and its humidity 80%. In the other experiments the airstream's humidity was either 25% or 80% with a constant temperature of 20 degrees C; the airstream was applied to the left or right nostril. In order to produce noxious chemical stimuli, gaseous CO2 was applied to the left nostril (36 stimuli of 200 ms; 65% v/v CO2; interstimulus interval 30 s). Subjects rated the pain intensity of the stimuli by means of a visual analogue scale (VAS). As an indicator for hyperalgesia, the subjective pain ratings to CO2 stimuli increased not only while they were applied at the inflamed site, but also during their application contralaterally to the inflamed side. These results demonstrate the occurrence of bilateral hyperalgesia to noxious chemical stimuli in the nasal mucosa following unilateral inflammation which indicates the involvement of central changes.

  12. Neurodegenerative mechanisms in Alzheimer disease. A role for oxidative damage in amyloid beta protein precursor-mediated cell death.

    PubMed

    Sopher, B L; Fukuchi, K; Kavanagh, T J; Furlong, C E; Martin, G M

    1996-01-01

    We have established a stably transformed human neuroblastoma cell line (MC65) that conditionally expresses a C-terminal derivative of the amyloid beta protein precursor (beta PP) termed S beta C (a fusion protein composed of the amino-17 and carboxyl-99 residues of beta PP). Conditional expression of S beta C (mediated by the withdrawal of tetracycline from the culture medium) induces pronounced nuclear DNA fragmentation and cytotoxicity in this cell line. These effects are enhanced by hyperoxygen and suppressed by hypooxygen and antioxidants. This cell line is relatively insensitive to the extracellular application of amyloid beta 25-35, and coculture experiments suggest that this cytotoxicity is mediated by an intracellular process. These findings suggest that the overexpression of the C-terminal domain of beta PP can disrupt normal cellular processes in these cells in such a way as to induce a directed (deoxyribonuclease-mediated) mechanism of cell death. This process appears to be modulated and/or mediated by a reactive oxygen specie(s) (ROS). Consistent with a role for ROS in the process of S beta C-mediated toxicity, we have found that the MC65 cell line is hypersensitive to oxidative stress and that it is this sensitivity that appears (at least in part) to underlie its susceptibility to S beta C.

  13. Characterisation and mechanisms of bradykinin-evoked pain in man using iontophoresis.

    PubMed

    Paterson, Kathryn J; Zambreanu, Laura; Bennett, David L H; McMahon, Stephen B

    2013-06-01

    Bradykinin (BK) is an inflammatory mediator that can evoke oedema and vasodilatation, and is a potent algogen signalling via the B1 and B2 G-protein coupled receptors. In naïve skin, BK is effective via constitutively expressed B2 receptors (B2R), while B1 receptors (B1R) are purported to be upregulated by inflammation. The aim of this investigation was to optimise BK delivery to investigate the algesic effects of BK and how these are modulated by inflammation. BK iontophoresis evoked dose- and temperature-dependent pain and neurogenic erythema, as well as thermal and mechanical hyperalgesia (P < 0.001 vs saline control). To differentiate the direct effects of BK from indirect effects mediated by histamine released from mast cells (MCs), skin was pretreated with compound 4880 to degranulate the MCs prior to BK challenge. The early phase of BK-evoked pain was reduced in degranulated skin (P < 0.001), while thermal and mechanical sensitisation, wheal, and flare were still evident. In contrast to BK, the B1R selective agonist des-Arg9-BK failed to induce pain or sensitise naïve skin. However, following skin inflammation induced by ultraviolet B irradiation, this compound produced a robust pain response. We have optimised a versatile experimental model by which BK and its analogues can be administered to human skin. We have found that there is an early phase of BK-induced pain which partly depends on the release of inflammatory mediators by MCs; however, subsequent hyperalgesia is not dependent on MC degranulation. In naïve skin, B2R signaling predominates, however, cutaneous inflammation results in enhanced B1R responses.

  14. Characterisation and mechanisms of bradykinin-evoked pain in man using iontophoresis.

    PubMed

    Paterson, Kathryn J; Zambreanu, Laura; Bennett, David L H; McMahon, Stephen B

    2013-06-01

    Bradykinin (BK) is an inflammatory mediator that can evoke oedema and vasodilatation, and is a potent algogen signalling via the B1 and B2 G-protein coupled receptors. In naïve skin, BK is effective via constitutively expressed B2 receptors (B2R), while B1 receptors (B1R) are purported to be upregulated by inflammation. The aim of this investigation was to optimise BK delivery to investigate the algesic effects of BK and how these are modulated by inflammation. BK iontophoresis evoked dose- and temperature-dependent pain and neurogenic erythema, as well as thermal and mechanical hyperalgesia (P < 0.001 vs saline control). To differentiate the direct effects of BK from indirect effects mediated by histamine released from mast cells (MCs), skin was pretreated with compound 4880 to degranulate the MCs prior to BK challenge. The early phase of BK-evoked pain was reduced in degranulated skin (P < 0.001), while thermal and mechanical sensitisation, wheal, and flare were still evident. In contrast to BK, the B1R selective agonist des-Arg9-BK failed to induce pain or sensitise naïve skin. However, following skin inflammation induced by ultraviolet B irradiation, this compound produced a robust pain response. We have optimised a versatile experimental model by which BK and its analogues can be administered to human skin. We have found that there is an early phase of BK-induced pain which partly depends on the release of inflammatory mediators by MCs; however, subsequent hyperalgesia is not dependent on MC degranulation. In naïve skin, B2R signaling predominates, however, cutaneous inflammation results in enhanced B1R responses. PMID:23422725

  15. Discrimination between platelet-mediated and coagulation-mediated mechanisms in a model of complex thrombus formation in vivo

    SciTech Connect

    Cadroy, Y.; Horbett, T.A.; Hanson, S.R.

    1989-04-01

    To study mechanisms of complex thrombus formation in vivo, and to compare the relative antithrombotic effects of anticoagulants and antiplatelet agents, a model was developed in baboons. Segments of collagen-coated tubing followed by two sequentially placed expansion chambers exhibiting disturbed flow patterns were exposed to native blood under laminar flow conditions. The device was incorporated for 1 hour into an exteriorized arteriovenous shunt in baboons under controlled blood flow (20 ml/min). Morphologic evaluation by scanning electron microscopy showed that thrombi associated with collagen were relatively rich in platelets but thrombi in the chambers were rich in fibrin and red cells. Deposition of indium 111-labeled platelets was continuously measured with a scintillation camera. Platelet deposition increased in a linear (collagen-coated segment) or exponential (chambers 1 and 2) fashion over time, with values after 40 minutes averaging 24.1 +/- 3.3 x 10(8) platelets (collagen segment), 16.7 +/- 3.4 x 10(8) platelets (chamber 1), and 8.4 +/- 2.4 x 10(8) platelets (chamber 2). Total fibrinogen deposition after 40 minutes was determined by using iodine 125-labeled baboon fibrinogen and averaged 0.58 +/- 0.14 mg in the collagen segment, 1.51 +/- 0.27 mg in chamber 1, and 0.95 +/- 0.25 mg in chamber 2. Plasma levels of beta-thromboglobulin (beta TG), platelet-factor 4 (PF4), and fibrinopeptide A (FPA) increased fourfold to fivefold after 60 minutes of blood exposure to the thrombotic device. Platelet deposition onto the collagen segment, chamber 1, and chamber 2 was linearly dependent on the circulating platelet count. Platelet accumulation in chamber 1 and chamber 2 was also dependent on the presence of the proximal collagen segment.

  16. Circadian clocks govern calorie restriction-mediated life span extension through BMAL1- and IGF-1-dependent mechanisms.

    PubMed

    Patel, Sonal A; Chaudhari, Amol; Gupta, Richa; Velingkaar, Nikkhil; Kondratov, Roman V

    2016-04-01

    Calorie restriction (CR) increases longevity in many species by unknown mechanisms. The circadian clock was proposed as a potential mediator of CR. Deficiency of the core component of the circadian clock-transcriptional factor BMAL1 (brain and muscle ARNT [aryl hydrocarbon receptor nuclear translocator]-like protein 1)-results in accelerated aging. Here we investigated the role of BMAL1 in mechanisms of CR. The 30% CR diet increased the life span of wild-type (WT) mice by 20% compared to mice on anad libitum(AL) diet but failed to increase life span ofBmal1(-/-)mice. BMAL1 deficiency impaired CR-mediated changes in the plasma levels of IGF-1 and insulin. We detected a statistically significantly reduction of IGF-1 in CRvs.AL by 50 to 70% in WT mice at several daily time points tested, while inBmal1(-/-)the reduction was not significant. Insulin levels in WT were reduced by 5 to 9%, whileBmal1(-/-)induced it by 10 to 35% at all time points tested. CR up-regulated the daily average expression ofBmal1(by 150%) and its downstream target genesPeriods(by 470% forPer1and by 130% forPer2). We propose that BMAL1 is an important mediator of CR, and activation of BMAL1 might link CR mechanisms with biologic clocks.-Patel, S. A., Chaudhari, A., Gupta, R., Velingkaar, N., Kondratov, R. V. Circadian clocks govern calorie restriction-mediated life span extension through BMAL1- and IGF-1-dependent mechanisms.

  17. HEPARAN SULFATE PROTEOGLYCAN-MEDIATED ENTRY PATHWAY FOR CHARGED TRI-PLATINUM COMPOUNDS. DIFFERENTIAL CELLULAR ACCUMULATION MECHANISMS FOR PLATINUM

    PubMed Central

    Silva, Heveline; Frézard, Frédéric; Peterson, Erica J.; Kabolizadeh, Peyman; Ryan, John J.; Farrell, Nicholas P.

    2012-01-01

    We examined the mechanism of accumulation of charged polynuclear platinum complexes (PPCs), based on analogy of polyarginine interactions with the cell surface heparan sulfate proteoglycan (HSPG) family of protein-linked glycosoaminoglycan polysaccharides (GAGs). GAGS such as heparan sulfate (HS) and chondroitin sulfate (CS) mediate the cellular entry of many charged molecules. Fluorescence microscopy and flow cytometry showed that PPCs, but not the neutral cisplatin or oxaliplatin, blocked the cellular entry of TAMRA-R9 (a nonarginine peptide, R9) coupled to the TAMRA fluorescent label 5-(and 6-)carboxytetramethylrhodamine) in Chinese Hamster Ovary (CHO), human colon carcinoma (HCT116), and osteosarcoma (SAOS-2) cells. Furthermore, detection of platinum accumulation in wt CHO, mutant CHO-pgsD-677 (lacking HS), and CHO-pgsA (lacking HS/CS) cells confirms that HSPG-mediated interactions are an important mechanism for PPC internalization, but not so for uncharged cisplatin and oxaliplatin. Endocytosis inhibitor studies show that macropinocytosis, a mechanism of cell entry for heparan sulfate GAGs and arginine-rich peptides, is important in the cellular accumulation of “non-covalent” TriplatinNC, and to a lesser degree, the covalently-binding BBR3464. Clathrin-mediated endocytosis, however, was not involved in either case. Overall the results suggest a new proteoglycan-mediated mechanism for cellular accumulation of PPCs not shared by cisplatin or oxaliplatin. The results have significant implications for rational design of platinum antitumor drugs with distinct biological profiles in comparison to the clinically-used agents as well as expanding the chemotypes for HS proteoglycan-dependent receptors. PMID:22494465

  18. Vimentin contributes to epithelial-mesenchymal transition cancer cell mechanics by mediating cytoskeletal organization and focal adhesion maturation

    PubMed Central

    Liu, Ching-Yi; Lin, Hsi-Hui; Tang, Ming-Jer; Wang, Yang-Kao

    2015-01-01

    Modulations of cytoskeletal organization and focal adhesion turnover correlate to tumorigenesis and epithelial-mesenchymal transition (EMT), the latter process accompanied by the loss of epithelial markers and the gain of mesenchymal markers (e.g., vimentin). Clinical microarray results demonstrated that increased levels of vimentin mRNA after chemotherapy correlated to a poor prognosis of breast cancer patients. We hypothesized that vimentin mediated the reorganization of cytoskeletons to maintain the mechanical integrity in EMT cancer cells. By using knockdown strategy, the results showed reduced cell proliferation, impaired wound healing, loss of directional migration, and increased large membrane extension in MDA-MB 231 cells. Vimentin depletion also induced reorganization of cytoskeletons and reduced focal adhesions, which resulted in impaired mechanical strength because of reduced cell stiffness and contractile force. In addition, overexpressing vimentin in MCF7 cells increased cell stiffness, elevated cell motility and directional migration, reoriented microtubule polarity, and increased EMT phenotypes due to the increased β1-integrin and the loss of junction protein E-cadherin. The EMT-related transcription factor slug was also mediated by vimentin. The current study demonstrated that vimentin serves as a regulator to maintain intracellular mechanical homeostasis by mediating cytoskeleton architecture and the balance of cell force generation in EMT cancer cells. PMID:25965826

  19. Intracellular mechanisms of hydrogen peroxide-mediated neutrophil adherence to cultured human endothelial cells.

    PubMed

    Okayama, N; Coe, L; Oshima, T; Itoh, M; Alexander, J S

    1999-03-01

    We examined which endothelial second messengers are involved in peroxide-mediated endothelial-neutrophil adhesion with respect to endothelial P-selectin expression and platelet-activating factor (PAF). Peroxide (0.5 mM)-mediated adhesion was blocked by a protein kinase C (PKC) inhibitor, Gö6976 (10 nM); an intracellular calcium chelator, TMB-8 (0.1 mM); and a protein kinase G (PKG) inhibitor, KT5823 (0.5 microM); but not by a tyrosine kinase inhibitor, genistein (1 microM), or a protein kinase A inhibitor, H-89 (0.1 microM). These data were consistent with the proadhesive effects of PMA (0.1 microM), a PKC activator; a calcium ionophore, A23187 (1 microM); and dibutyryl cGMP (0.5 and 1 mM); but not phenylarsine oxide (0.1 mM), a tyrosine phosphatase inhibitor, or dibutyryl cAMP (1 mM). Conversely, peroxide-mediated P-selectin expression was blocked by Gö6976 and KT5823, but not by TMB-8. These data are strengthened by the observation that PMA and dibutyryl cGMP, but not A23187, increased P-selectin expression. WEB 2086 (10 microM), a PAF-receptor antagonist, blocked peroxide-, PMA-, and A23187-mediated adhesion, but not peroxide-mediated P-selectin expression. PAF itself (10 nM) stimulated adhesion, but not P-selectin expression. These data indicate that PKC and PKG are involved in peroxide-mediated neutrophil adhesion via P-selectin mobilization and PAF synthesis; however, intracellular calcium appears to mediate adhesion only through PAF synthesis.

  20. Sensitization of lamina I spinoparabrachial neurons parallels heat hyperalgesia in the chronic constriction injury model of neuropathic pain.

    PubMed

    Andrew, David

    2009-05-01

    It has been proposed that spinal lamina I neurons with ascending axons that project to the midbrain play a crucial role in hyperalgesia. To test this hypothesis the quantitative properties of lamina I spinoparabrachial neurons in the chronic constriction injury (CCI) model of neuropathic pain were compared to those of unoperated and sham-operated controls. Behavioural testing showed that animals with a CCI exhibited heat hyperalgesia within 4 days of the injury, and this hyperalgesia persisted throughout the 14-day post-operative testing period. In the CCI, nociceptive lamina I spinoparabrachial neurons had heat thresholds that were significantly lower than controls (43.0 +/- 2.8 degrees C vs. 46.7 +/- 2.6 degrees C; P < 10(-4), ANOVA). Nociceptive lamina I spinoparabrachial neurons were also significantly more responsive to graded heat stimuli in the CCI, compared to controls (P < 0.02, 2-factor repeated-measures ANOVA), and increased after-discharges were also observed. Furthermore, the heat-evoked stimulus-response functions of lamina I spinoparabrachial neurons in CCI animals co-varied significantly (P < 0.03, ANCOVA) with the amplitude of heat hyperalgesia determined behaviourally. Taken together these results are consistent with the hypothesis that lamina I spinoparabrachial neurons have an important mechanistic role in the pathophysiology of neuropathic pain.

  1. Irinotecan-Induced Gastrointestinal Dysfunction and Pain Are Mediated by Common TLR4-Dependent Mechanisms.

    PubMed

    Wardill, Hannah R; Gibson, Rachel J; Van Sebille, Ysabella Z A; Secombe, Kate R; Coller, Janet K; White, Imogen A; Manavis, Jim; Hutchinson, Mark R; Staikopoulos, Vasiliki; Logan, Richard M; Bowen, Joanne M

    2016-06-01

    Strong epidemiological data indicate that chemotherapy-induced gut toxicity and pain occur in parallel, indicating common underlying mechanisms. We have recently outlined evidence suggesting that TLR4 signaling may contribute to both side effects. We therefore aimed to determine if genetic deletion of TLR4 improves chemotherapy-induced gut toxicity and pain. Forty-two female wild-type (WT) and 42 Tlr4 null (-/-) BALB/c mice weighing between 18 and 25 g (10-13 weeks) received a single 270 mg/kg (i.p.) dose of irinotecan hydrochloride or vehicle control and were killed at 6, 24, 48, 72, and 96 hours. Bacterial sequencing was conducted on cecal samples of control animals to determine the gut microbiome profile. Gut toxicity was assessed using validated clinical and histopathologic markers, permeability assays, and inflammatory markers. Chemotherapy-induced pain was assessed using the validated rodent facial grimace criteria, as well as immunologic markers of glial activation in the lumbar spinal cord. TLR4 deletion attenuated irinotecan-induced gut toxicity, with improvements in weight loss (P = 0.0003) and diarrhea (P < 0.0001). Crypt apoptosis was significantly decreased in BALB/c-Tlr4(-/-billy) mice (P < 0.0001), correlating with lower mucosal injury scores (P < 0.005). Intestinal permeability to FITC-dextran (4 kDa) and LPS translocation was greater in WT mice than in BALB/c-Tlr4(-/-billy) (P = 0.01 and P < 0.0001, respectively). GFAP staining in the lumbar spinal cord, indicative of astrocytic activation, was increased at 6 and 72 hours in WT mice compared with BALB/c-Tlr4(-/-billy) mice (P = 0.008, P = 0.01). These data indicate that TLR4 is uniquely positioned to mediate irinotecan-induced gut toxicity and pain, highlighting the possibility of a targetable gut/CNS axis for improved toxicity outcomes. Mol Cancer Ther; 15(6); 1376-86. ©2016 AACR. PMID:27197307

  2. Potentiation of μ–opioid receptor–mediated signaling by ketamine

    PubMed Central

    Gupta, Achla; Devi, Lakshmi A.; Gomes, Ivone

    2013-01-01

    Ketamine, a clinically relevant drug, has been shown to enhance opioid-induced analgesia and prevent hyperalgesia. However, the molecular mechanisms involved are not clearly understood. As previous studies found that activation of opioid receptors leads to the phosphorylation of mitogen-activated protein kinases, we investigated whether ketamine could modulate μ-opioid receptor (μOR)-mediated ERK1/2 phosphorylation. We find that acute treatment with ketamine enhances (~2- to 3-fold) the levels of opioid-induced ERK1/2 phosphorylation in recombinant as well as cells endogenously expressing μOR. Interestingly, we find that in the absence of ketamine ERK1/2 signaling is desensitized 10 min after opioid exposure whereas in its presence significant levels (~3-fold over basal) are detected. In addition, ketamine increases the rate of resensitization of opioid-mediated ERK1/2 signaling (15 min in its presence vs. 30 min in its absence). These results suggest that ketamine increases the effectiveness of opiate-induced signaling by affecting multiple mechanisms. In addition, these effects are observed in heterologous cells expressing μOR suggesting a non-NMDA receptor-mediated action of ketamine. Together this could, in part, account for the observed effects of ketamine on the enhancement of the analgesic effects of opiates as well as in the duration of opiate-induced analgesia. PMID:21692801

  3. Sex Difference in Oxytocin-Induced Anti-Hyperalgesia at the Spinal Level in Rats with Intraplantar Carrageenan-Induced Inflammation

    PubMed Central

    Chow, Lok-Hi; Chen, Yuan-Hao; Wu, Wan-Chuan; Chang, En-Pei; Huang, Eagle Yi-Kung

    2016-01-01

    Previously, we demonstrated intrathecal administration of oxytocin strongly induced anti-hyperalgesia in male rats. By using an oxytocin-receptor antagonist (atosiban), the descending oxytocinergic pathway was found to regulate inflammatory hyperalgesia in our previous study using male rats. The activity of this neural pathway is elevated during hyperalgesia, but whether this effect differs in a sex-dependent manner remains unknown. We conducted plantar tests on adult male and female virgin rats in which paw inflammation was induced using carrageenan. Exogenous (i.t.) application of oxytocin exerted no anti-hyperalgesic effect in female rats, except at an extremely high dose. Female rats exhibited similar extent of hyperalgesia to male rats did when the animals received the same dose of carrageenan. When atosiban was administered alone, the severity of hyperalgesia was not increased in female rats. Moreover, insulin-regulated aminopeptidase (IRAP) was expressed at higher levels in the spinal cords of female rats compared with those of male rats. Oxytocin-induced anti-hyperalgesia exhibits a sex-dependent difference in rats. This difference can partially result from the higher expression of IRAP in the spinal cords of female rats, because IRAP functions as an enzyme that degrades oxytocin. Our study confirms the existence of a sex difference in oxytocin-induced anti-hyperalgesia at the spinal level in rats. PMID:27606886

  4. Sex Difference in Oxytocin-Induced Anti-Hyperalgesia at the Spinal Level in Rats with Intraplantar Carrageenan-Induced Inflammation.

    PubMed

    Chow, Lok-Hi; Chen, Yuan-Hao; Wu, Wan-Chuan; Chang, En-Pei; Huang, Eagle Yi-Kung

    2016-01-01

    Previously, we demonstrated intrathecal administration of oxytocin strongly induced anti-hyperalgesia in male rats. By using an oxytocin-receptor antagonist (atosiban), the descending oxytocinergic pathway was found to regulate inflammatory hyperalgesia in our previous study using male rats. The activity of this neural pathway is elevated during hyperalgesia, but whether this effect differs in a sex-dependent manner remains unknown. We conducted plantar tests on adult male and female virgin rats in which paw inflammation was induced using carrageenan. Exogenous (i.t.) application of oxytocin exerted no anti-hyperalgesic effect in female rats, except at an extremely high dose. Female rats exhibited similar extent of hyperalgesia to male rats did when the animals received the same dose of carrageenan. When atosiban was administered alone, the severity of hyperalgesia was not increased in female rats. Moreover, insulin-regulated aminopeptidase (IRAP) was expressed at higher levels in the spinal cords of female rats compared with those of male rats. Oxytocin-induced anti-hyperalgesia exhibits a sex-dependent difference in rats. This difference can partially result from the higher expression of IRAP in the spinal cords of female rats, because IRAP functions as an enzyme that degrades oxytocin. Our study confirms the existence of a sex difference in oxytocin-induced anti-hyperalgesia at the spinal level in rats. PMID:27606886

  5. Molecular mechanism for USP7-mediated DNMT1 stabilization by acetylation

    NASA Astrophysics Data System (ADS)

    Cheng, Jingdong; Yang, Huirong; Fang, Jian; Ma, Lixiang; Gong, Rui; Wang, Ping; Li, Ze; Xu, Yanhui

    2015-05-01

    DNMT1 is an important epigenetic regulator that plays a key role in the maintenance of DNA methylation. Here we determined the crystal structure of DNMT1 in complex with USP7 at 2.9 Å resolution. The interaction between the two proteins is primarily mediated by an acidic pocket in USP7 and Lysine residues within DNMT1's KG linker. This intermolecular interaction is required for USP7-mediated stabilization of DNMT1. Acetylation of the KG linker Lysine residues impair DNMT1-USP7 interaction and promote the degradation of DNMT1. Treatment with HDAC inhibitors results in an increase in acetylated DNMT1 and decreased total DNMT1 protein. This negative correlation is observed in differentiated neuronal cells and pancreatic cancer cells. Our studies reveal that USP7-mediated stabilization of DNMT1 is regulated by acetylation and provide a structural basis for the design of inhibitors, targeting the DNMT1-USP7 interaction surface for therapeutic applications.

  6. Relation of media exposure to eating disorder symptomatology: an examination of mediating mechanisms.

    PubMed

    Stice, E; Schupak-Neuberg, E; Shaw, H E; Stein, R I

    1994-11-01

    Although investigators have postulated that the thin ideal for women espoused in the media is related to the high rates of eating disorders among females, little research has examined the relation between media exposure and eating pathology. This study assessed the relation of media exposure to eating disorder symptoms and tested whether gender-role endorsement, ideal-body stereotype internalization, and body satisfaction mediated this effect. In data from 238 female undergraduates, structural equation modeling revealed a direct effect of media exposure on eating disorder symptoms. Furthermore, mediational linkages were found for gender-role endorsement, ideal body stereotype internalization, and body satisfaction. The results support the assertion that internalization of sociocultural pressures mediate the adverse effects of the thin ideal.

  7. Genetics of immune-mediated disorders: from genome-wide association to molecular mechanism

    PubMed Central

    Kumar, Vinod; Wijmenga, Cisca; Xavier, Ramnik J.

    2016-01-01

    Genetic association studies have identified not only hundreds of susceptibility loci to immune-mediated diseases but also pinpointed causal amino-acid variants of HLA genes that contribute to many autoimmune reactions. Majority of non-HLA genetic variants are located within non-coding regulatory region. Expression QTL studies have shown that these variants affect disease mainly by regulating gene expression. We discuss recent findings on shared genetic loci between infectious and immune-mediated diseases and provide potential clues to explore genetic associations in the context of these infectious agents. We propose that the interdisciplinary studies (genetics-genomics-immunology-infection-bioinformatics) are the future post-GWAS approaches to advance our understanding of the pathogenesis of immune-mediated diseases. PMID:25458995

  8. Effects of songs with prosocial lyrics on prosocial behavior: further evidence and a mediating mechanism.

    PubMed

    Greitemeyer, Tobias

    2009-11-01

    Previous research has shown that exposure to prosocial songs increased the accessibility of prosocial thoughts, led to more interpersonal empathy, and fostered helping behavior. However, inasmuch as cognition, affect, and behavior were measured in different studies, it remained unclear what variable constituted the mediating path from media exposure to action. This was tested in the present research. In four studies, listening to songs with prosocial, relative to neutral, lyrics increased helping behavior. This effect was mediated by interpersonal empathy. The results are consistent with the general learning model and point to the importance of the affective route in explaining how media exposure influences social behavior. PMID:19648562

  9. Adiponectin-Mediated Heme Oxygenase-1 Induction Protects Against Iron-Induced Liver Injury via a PPARα-Dependent Mechanism

    PubMed Central

    Lin, Heng; Yu, Chun-Hsien; Jen, Chih-Yu; Cheng, Ching-Feng; Chou, Ying; Chang, Chih-Cheng; Juan, Shu-Hui

    2010-01-01

    Protective effects of adiponectin (APN; an adipocytokine) were shown against various oxidative challenges; however, its therapeutic implications and the mechanisms underlying hepatic iron overload remain unclear. Herein, we show that the deleterious effects of iron dextran on liver function and iron deposition were significantly reversed by adiponectin gene therapy, which was accompanied by AMP-activated protein kinase (AMPK) phosphorylation and heme oxygenase (HO)-1 induction. Furthermore, AMPK-mediated peroxisome proliferator-activated receptor-α (PPARα) activation by APN was ascribable to HO-1 induction. Additionally, we revealed direct transcriptional regulation of HO-1 by the binding of PPARα to a PPAR-responsive element (PPRE) by various experimental assessments. Interestingly, overexpression of HO-1 in hepatocytes mimicked the protective effect of APN in attenuating iron-mediated injury, whereas it was abolished by SnPP and small interfering HO-1. Furthermore, bilirubin, the end-product of the HO-1 reaction, but not CO, protected hepatocytes from iron dextran-mediated caspase activation. Herein, we demonstrate a novel functional PPRE in the promoter regions of HO-1, and APN-mediated HO-1 induction elicited an antiapoptotic effect and a decrease in iron deposition in hepatocytes subjected to iron challenge. PMID:20709802

  10. Molecular Mechanisms for cAMP-Mediated Immunoregulation in T cells – Role of Anchored Protein Kinase A Signaling Units

    PubMed Central

    Wehbi, Vanessa L.; Taskén, Kjetil

    2016-01-01

    The cyclic AMP/protein kinase A (cAMP/PKA) pathway is one of the most common and versatile signal pathways in eukaryotic cells. A-kinase anchoring proteins (AKAPs) target PKA to specific substrates and distinct subcellular compartments providing spatial and temporal specificity for mediation of biological effects channeled through the cAMP/PKA pathway. In the immune system, cAMP is a potent negative regulator of T cell receptor-mediated activation of effector T cells (Teff) acting through a proximal PKA/Csk/Lck pathway anchored via a scaffold consisting of the AKAP Ezrin holding PKA, the linker protein EBP50, and the anchoring protein phosphoprotein associated with glycosphingolipid-enriched microdomains holding Csk. As PKA activates Csk and Csk inhibits Lck, this pathway in response to cAMP shuts down proximal T cell activation. This immunomodulating pathway in Teff mediates clinically important responses to regulatory T cell (Treg) suppression and inflammatory mediators, such as prostaglandins (PGs), adrenergic stimuli, adenosine, and a number of other ligands. A major inducer of T cell cAMP levels is PG E2 (PGE2) acting through EP2 and EP4 prostanoid receptors. PGE2 plays a crucial role in the normal physiological control of immune homeostasis as well as in inflammation and cancer immune evasion. Peripherally induced Tregs express cyclooxygenase-2, secrete PGE2, and elicit the immunosuppressive cAMP pathway in Teff as one tumor immune evasion mechanism. Moreover, a cAMP increase can also be induced by indirect mechanisms, such as intercellular transfer between T cells. Indeed, Treg, known to have elevated levels of intracellular cAMP, may mediate their suppressive function by transferring cAMP to Teff through gap junctions, which we speculate could also be regulated by PKA/AKAP complexes. In this review, we present an updated overview on the influence of cAMP-mediated immunoregulatory mechanisms acting through localized cAMP signaling and the therapeutical

  11. Molecular Mechanisms for cAMP-Mediated Immunoregulation in T cells - Role of Anchored Protein Kinase A Signaling Units.

    PubMed

    Wehbi, Vanessa L; Taskén, Kjetil

    2016-01-01

    The cyclic AMP/protein kinase A (cAMP/PKA) pathway is one of the most common and versatile signal pathways in eukaryotic cells. A-kinase anchoring proteins (AKAPs) target PKA to specific substrates and distinct subcellular compartments providing spatial and temporal specificity for mediation of biological effects channeled through the cAMP/PKA pathway. In the immune system, cAMP is a potent negative regulator of T cell receptor-mediated activation of effector T cells (Teff) acting through a proximal PKA/Csk/Lck pathway anchored via a scaffold consisting of the AKAP Ezrin holding PKA, the linker protein EBP50, and the anchoring protein phosphoprotein associated with glycosphingolipid-enriched microdomains holding Csk. As PKA activates Csk and Csk inhibits Lck, this pathway in response to cAMP shuts down proximal T cell activation. This immunomodulating pathway in Teff mediates clinically important responses to regulatory T cell (Treg) suppression and inflammatory mediators, such as prostaglandins (PGs), adrenergic stimuli, adenosine, and a number of other ligands. A major inducer of T cell cAMP levels is PG E2 (PGE2) acting through EP2 and EP4 prostanoid receptors. PGE2 plays a crucial role in the normal physiological control of immune homeostasis as well as in inflammation and cancer immune evasion. Peripherally induced Tregs express cyclooxygenase-2, secrete PGE2, and elicit the immunosuppressive cAMP pathway in Teff as one tumor immune evasion mechanism. Moreover, a cAMP increase can also be induced by indirect mechanisms, such as intercellular transfer between T cells. Indeed, Treg, known to have elevated levels of intracellular cAMP, may mediate their suppressive function by transferring cAMP to Teff through gap junctions, which we speculate could also be regulated by PKA/AKAP complexes. In this review, we present an updated overview on the influence of cAMP-mediated immunoregulatory mechanisms acting through localized cAMP signaling and the therapeutical

  12. A tarantula spider toxin, GsMTx4, reduces mechanical and neuropathic pain.

    PubMed

    Park, Seung Pyo; Kim, Byung Moon; Koo, Jae Yeon; Cho, Hawon; Lee, Chang Hoon; Kim, Misook; Na, Heung Sik; Oh, Uhtaek

    2008-07-01

    Mechanosensitive channels mediate various physiological functions including s