Browsing by Subject "Neuralgia"

Now showing 1 - 6 of 6
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    Carbamazepine Potentiates the Effectiveness of Morphine in a Rodent Model of Neuropathic Pain
    (Public Library of Science, 2014-09-15) Due, Michael R.; Yang, Xiao-Fang; Allette, Yohance M.; Randolph, Aaron L.; Ripsch, Matthew S.; Wilson, Sarah M.; Dustrude, Erik T.; Khanna, Rajesh; White, Fletcher A.; Anesthesia, School of Medicine
    Approximately 60% of morphine is glucuronidated to morphine-3-glucuronide (M3G) which may aggravate preexisting pain conditions. Accumulating evidence indicates that M3G signaling through neuronal Toll-like receptor 4 (TLR4) may be central to this proalgesic signaling event. These events are known to include elevated neuronal excitability, increased voltage-gated sodium (NaV) current, tactile allodynia and decreased opioid analgesic efficacy. Using an in vitro ratiometric-based calcium influx analysis of acutely dissociated small and medium-diameter neurons derived from lumbar dorsal root ganglion (DRG), we observed that M3G-sensitive neurons responded to lipopolysaccharide (LPS) and over 35% of these M3G/LPS-responsive cells exhibited sensitivity to capsaicin. In addition, M3G-exposed sensory neurons significantly increased excitatory activity and potentiated NaV current as measured by current and voltage clamp, when compared to baseline level measurements. The M3G-dependent excitability and potentiation of NaV current in these sensory neurons could be reversed by the addition of carbamazepine (CBZ), a known inhibitor of several NaV currents. We then compared the efficacy between CBZ and morphine as independent agents, to the combined treatment of both drugs simultaneously, in the tibial nerve injury (TNI) model of neuropathic pain. The potent anti-nociceptive effects of morphine (5 mg/kg, i.p.) were observed in TNI rodents at post-injury day (PID) 7-14 and absent at PID21-28, while administration of CBZ (10 mg/kg, i.p.) alone failed to produce anti-nociceptive effects at any time following TNI (PID 7-28). In contrast to either drug alone at PID28, the combination of morphine and CBZ completely attenuated tactile hyperalgesia in the rodent TNI model. The basis for the potentiation of morphine in combination with CBZ may be due to the effects of a latent upregulation of NaV1.7 in the DRG following TNI. Taken together, our observations demonstrate a potential therapeutic use of morphine and CBZ as a combinational treatment for neuropathic pain.
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    Challenging the catechism of therapeutics for chronic neuropathic pain: targeting CaV2.2 interactions with CRMP2 peptides
    (Elsevier, 2013-12-17) Feldman, Polina; Khanna, Rajesh; Department of Pharmacology and Toxicology, IU School of Medicine
    Chronic neuropathic pain management is a worldwide concern. Pharmaceutical companies globally have historically targeted ion channels as the therapeutic catechism with many blockbuster successes. Remarkably, no new pain therapeutic has been approved by European or American regulatory agencies over the last decade. This article will provide an overview of an alternative approach to ion channel drug discovery: targeting regulators of ion channels, specifically focusing on voltage-gated calcium channels. We will highlight the discovery of an anti-nociceptive peptide derived from a novel calcium channel interacting partner – the collapsin response mediator protein 2 (CRMP2). In vivo administration of this peptide reduces pain behavior in a number of models of neuropathic pain without affecting sympathetic-associated cardiovascular activity, memory retrieval, sensorimotor function, or depression. A CRMP2-derived peptide analgesic, with restricted access to the CNS, represents a completely novel approach to the treatment of severe pain with an improved safety profile. As peptides now represent one of the fastest growing classes of new drugs, it is expected that peptide targeting of protein interactions within the calcium channel complex may be a paradigm shift in ion channel drug discovery.
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    Dual regulation of voltage- and ligand-gated calcium channels by collapsin response mediator protein 2
    (2013-10-07) Brittain, Joel Matthew; Khanna, Rajesh; Cummins, Theodore R.; Oxford, G. S.; Quilliam, Lawrence; Thurmond, Debbie C.
    Synaptic transmission is coordinated by a litany of protein-protein interactions that rely on the proper localization and function of pre- and post-synaptic Ca2+ channels. The axonal guidance/specification collapsin response mediator protein-2 (CRMP-2) was identified as a potential partner of the pre-synaptic N-type voltage-gated Ca2+ channel (CaV2.2). CRMP-2 bound directly to CaV2.2 in two regions; the channel domain I-II intracellular loop and the distal C-terminus. Both proteins co-localized within presynaptic sites in hippocampal neurons. Overexpression in hippocampal neurons of a CRMP-2 protein fused to EGFP caused a significant increase in Ca2+ channel current density whereas lentivirus-mediated CRMP-2 knockdown abolished this effect. Cell surface biotinylation studies showed an increased number of CaV2.2 at the cell surface in CRMP-2–overexpressing neurons. Both activity- and CRMP-2-phosphoryation altered the interaction between CaV2.2 and CRMP-2. I identified a CRMP-2-derived peptide (called CBD3) that bound CaV2.2 and effectively disrupted the interaction between CaV2.2 and CRMP-2. CBD3 peptide fused to the HIV TAT protein (TAT-CBD3) decreased neuropeptide release from sensory neurons and excitatory synaptic transmission in dorsal horn neurons, and reversed neuropathic hypersensitivity produced by an antiretroviral drug. Unchecked Ca2+ influx via N-methyl-D-aspartate receptors (NMDARs) has been linked to activation of neurotoxic cascades culminating in cell death (i.e. excitotoxicity). CRMP-2 was suggested to affect NMDAR trafficking and possibly involved in neuronal survival following excitotoxicity. Based upon these studies, I hypothesized that a peptide from CRMP2 could preserve neurons in the face of excitotoxic challenges. Lentiviral–mediated CRMP2 knockdown or treatment with TAT-CBD3 blocked neuronal death following glutamate exposure likely via blunting toxicity from NMDAR-mediated delayed calcium deregulation. TAT-CBD3 induced internalization of the NMDAR subunit NR2B in dendritic spines without altering somal surface expression. TAT-CBD3 reduced NMDA-mediated Ca2+-influx and currents in cultured neurons. The presented work validates CRMP-2 as a novel modulator of pre- and post-synaptic Ca2+ channels and provides evidence that the TAT-CBD3 peptide could be useful as a potential therapeutic for both chronic neuropathic pain and excitotoxicity following stroke or other neuronal insults.
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    Identification of a functional interaction of HMGB1 with Receptor for Advanced Glycation End-products in a model of neuropathic pain
    (Elsevier, 2014-11) Allette, Yohance M.; Due, Michael R.; Wilson, Sarah M.; Feldman, Polina; Ripsch, Matthew S.; Khanna, Rajesh; White, Fletcher A.; Department of Anesthesia, IU School of Medicine
    Recent studies indicate that the release of high mobility group box 1 (HMGB1) following nerve injury may play a central role in the pathogenesis of neuropathic pain. HMGB1 is known to influence cellular responses within the nervous system via two distinct receptor families; the Receptor for Advanced Glycation End-products (RAGE) and Toll-like receptors (TLRs). The degree to which HMGB1 activates a receptor is thought to be dependent upon the oxidative state of the ligand, resulting in the functional isoforms of all-thiol HMGB1 (at-HMGB1) acting through RAGE, and disufide HMGB1 (ds-HMGB1) interacting with TLR4. Though it is known that dorsal root ganglia (DRG) sensory neurons exposed to HMGB1 and TLR4 agonists can influence excitation, the degree to which at-HMGB1 signaling through neuronal RAGE contributes to neuropathic pain is unknown. Here we demonstrate that at-HMGB1 activation of nociceptive neurons is dependent on RAGE and not TLR4. To distinguish the possible role of RAGE on neuropathic pain, we characterized the changes in RAGE mRNA expression up to one month after tibial nerve injury (TNI). RAGE mRNA expression in lumbar dorsal root ganglion (DRG) is substantially increased by post-injury day (PID) 28 when compared with sham injured rodents. Protein expression at PID28 confirms this injury-induced event in the DRG. Moreover, a single exposure to monoclonal antibody to RAGE (RAGE Ab) failed to abrogate pain behavior at PID 7, 14 and 21. However, RAGE Ab administration produced reversal of mechanical hyperalgesia on PID28. Thus, at-HMGB1 activation through RAGE may be responsible for sensory neuron sensitization and mechanical hyperalgesia associated with chronic neuropathic pain states.
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    Impact of pain and adverse health outcomes on long-term US testicular cancer survivors
    (Oxford University Press, 2024) Dinh, Paul C., Jr.; Monahan, Patrick O.; Fosså, Sophie D.; Sesso, Howard D.; Feldman, Darren R.; Dolan, M. Eileen; Nevel, Kathryn; Kincaid, John; Vaughn, David J.; Martin, Neil E.; Sanchez, Victoria A.; Einhorn, Lawrence H.; Frisina, Robert; Fung, Chunkit; Kroenke, Kurt; Travis, Lois B.; Medicine, School of Medicine
    Background: No study has quantified the impact of pain and other adverse health outcomes on global physical and mental health in long-term US testicular cancer survivors or evaluated patient-reported functional impairment due to pain. Methods: Testicular cancer survivors given cisplatin-based chemotherapy completed validated surveys, including Patient-Reported Outcomes Measurement Information System v1.2 global physical and mental health, Patient-Reported Outcomes Measurement Information System pain questionnaires, and others. Multivariable linear regression examined relationships between 25 adverse health outcomes with global physical and mental health and pain-interference scores. Adverse health outcomes with a β^ of more than 2 are clinically important and reported below. Results: Among 358 testicular cancer survivors (median age = 46 years, interquartile range [IQR] = 38-53 years; median time since chemotherapy = 10.7 years, IQR = 7.2-16.0 years), median adverse health outcomes number was 5 (IQR = 3-7). A total of 12% testicular cancer survivors had 10 or more adverse health outcomes, and 19% reported chemotherapy-induced neuropathic pain. Increasing adverse health outcome numbers were associated with decreases in physical and mental health (P < .0001 each). In multivariable analyses, chemotherapy-induced neuropathic pain (β^ = -3.72; P = .001), diabetes (β^ = -4.41; P = .037), obesity (β^ = -2.01; P = .036), and fatigue (β^ = -8.58; P < .0001) were associated with worse global mental health, while being married or living as married benefited global mental health (β^ = 3.63; P = .0006). Risk factors for pain-related functional impairment included lower extremity location (β^ = 2.15; P = .04) and concomitant peripheral artery disease (β^ = 4.68; P < .001). Global physical health score reductions were associated with diabetes (β^ = -3.81; P = .012), balance or equilibrium problems (β^ = -3.82; P = .003), cognitive dysfunction (β^ = -4.43; P < .0001), obesity (β^ = -3.09; P < .0001), peripheral neuropathy score (β^ = -2.12; P < .0001), and depression (β^ = -3.17; P < .0001). Conclusions: Testicular cancer survivors suffer adverse health outcomes that negatively impact long-term global mental health, global physical health, and pain-related functional status. Clinically important factors associated with worse physical and mental health identify testicular cancer survivors requiring closer monitoring, counseling, and interventions. Chemotherapy-induced neuropathic pain must be addressed, given its detrimental impact on patient-reported functional status and mental health 10 or more years after treatment.
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    Inhibition of the Ubc9 E2 SUMO-conjugating enzyme-CRMP2 interaction decreases NaV1.7 currents and reverses experimental neuropathic pain
    (Lippincott, Williams & Wilkins, 2018-10) François-Moutal, Liberty; Dustrude, Erik T.; Wang, Yue; Brustovetsky, Tatiana; Dorame, Angie; Ju, Weina; Moutal, Aubin; Perez-Miller, Samantha; Brustovetsky, Nickolay; Gokhale, Vijay; Khanna, May; Khanna, Rajesh; Pharmacology and Toxicology, School of Medicine
    We previously reported that destruction of the small ubiquitin-like modifier (SUMO) modification site in the axonal collapsin response mediator protein 2 (CRMP2) was sufficient to selectively decrease trafficking of the voltage-gated sodium channel NaV1.7 and reverse neuropathic pain. Here, we further interrogate the biophysical nature of the interaction between CRMP2 and the SUMOylation machinery, and test the hypothesis that a rationally designed CRMP2 SUMOylation motif (CSM) peptide can interrupt E2 SUMO-conjugating enzyme Ubc9-dependent modification of CRMP2 leading to a similar suppression of NaV1.7 currents. Microscale thermophoresis and amplified luminescent proximity homogeneous alpha assay revealed a low micromolar binding affinity between CRMP2 and Ubc9. A heptamer peptide harboring CRMP2's SUMO motif, also bound with similar affinity to Ubc9, disrupted the CRMP2-Ubc9 interaction in a concentration-dependent manner. Importantly, incubation of a tat-conjugated cell-penetrating peptide (t-CSM) decreased sodium currents, predominantly NaV1.7, in a model neuronal cell line. Dialysis of t-CSM peptide reduced CRMP2 SUMOylation and blocked surface trafficking of NaV1.7 in rat sensory neurons. Fluorescence dye-based imaging in rat sensory neurons demonstrated inhibition of sodium influx in the presence of t-CSM peptide; by contrast, calcium influx was unaffected. Finally, t-CSM effectively reversed persistent mechanical and thermal hypersensitivity induced by a spinal nerve injury, a model of neuropathic pain. Structural modeling has now identified a pocket-harboring CRMP2's SUMOylation motif that, when targeted through computational screening of ligands/molecules, is expected to identify small molecules that will biochemically and functionally target CRMP2's SUMOylation to reduce NaV1.7 currents and reverse neuropathic pain.