Browsing by Subject "CGRP"

Now showing 1 - 5 of 5
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    Dissecting the role of the CRMP2–neurofibromin complex on pain behaviors
    (Wolters Kluwer, 2017-11) Moutal, Aubin; Wang, Yue; Yang, Xiaofang; Ji, Yingshi; Luo, Shizhen; Dorame, Angie; Bellampalli, Shreya S.; Chew, Lindsey A.; Cai, Song; Dustrude, Erik T.; Keener, James E.; Marty, Michael T.; Vanderah, Todd W.; Khanna, Rajesh; Psychiatry, School of Medicine
    Neurofibromatosis type 1 (NF1), a genetic disorder linked to inactivating mutations or a homozygous deletion of the Nf1 gene, is characterized by tumorigenesis, cognitive dysfunction, seizures, migraine, and pain. Omic studies on human NF1 tissues identified an increase in the expression of collapsin response mediator protein 2 (CRMP2), a cytosolic protein reported to regulate the trafficking and activity of presynaptic N-type voltage-gated calcium (Cav2.2) channels. Because neurofibromin, the protein product of the Nf1 gene, binds to and inhibits CRMP2, the neurofibromin-CRMP2 signaling cascade will likely affect Ca channel activity and regulate nociceptive neurotransmission and in vivo responses to noxious stimulation. Here, we investigated the function of neurofibromin-CRMP2 interaction on Cav2.2. Mapping of >275 peptides between neurofibromin and CRMP2 identified a 15-amino acid CRMP2-derived peptide that, when fused to the tat transduction domain of HIV-1, inhibited Ca influx in dorsal root ganglion neurons. This peptide mimics the negative regulation of CRMP2 activity by neurofibromin. Neurons treated with tat-CRMP2/neurofibromin regulating peptide 1 (t-CNRP1) exhibited a decreased Cav2.2 membrane localization, and uncoupling of neurofibromin-CRMP2 and CRMP2-Cav2.2 interactions. Proteomic analysis of a nanodisc-solubilized membrane protein library identified syntaxin 1A as a novel CRMP2-binding protein whose interaction with CRMP2 was strengthened in neurofibromin-depleted cells and reduced by t-CNRP1. Stimulus-evoked release of calcitonin gene-related peptide from lumbar spinal cord slices was inhibited by t-CNRP1. Intrathecal administration of t-CNRP1 was antinociceptive in experimental models of inflammatory, postsurgical, and neuropathic pain. Our results demonstrate the utility of t-CNRP1 to inhibit CRMP2 protein-protein interactions for the potential treatment of pain.
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    Lasmiditan mechanism of action – review of a selective 5-HT1F agonist
    (Springer, 2020-06-10) Clemow, David B.; Johnson, Kirk W.; Hochstetler, Helen M.; Ossipov, Michael H.; Hake, Ann M.; Blumenfeld, Andrew M.; Neurology, School of Medicine
    Migraine is a leading cause of disability worldwide, but it is still underdiagnosed and undertreated. Research on the pathophysiology of this neurological disease led to the discovery that calcitonin gene-related peptide (CGRP) is a key neuropeptide involved in pain signaling during a migraine attack. CGRP-mediated neuronal sensitization and glutamate-based second- and third-order neuronal signaling may be an important component involved in migraine pain. The activation of several serotonergic receptor subtypes can block the release of CGRP, other neuropeptides, and neurotransmitters, and can relieve the symptoms of migraine. Triptans were the first therapeutics developed for the treatment of migraine, working through serotonin 5-HT1B/1D receptors. The discovery that the serotonin 1F (5-HT1F) receptor was expressed in the human trigeminal ganglion suggested that this receptor subtype may have a role in the treatment of migraine. The 5-HT1F receptor is found on terminals and cell bodies of trigeminal ganglion neurons and can modulate the release of CGRP from these nerves. Unlike 5-HT1B receptors, the activation of 5-HT1F receptors does not cause vasoconstriction. The potency of different serotonergic agonists towards 5-HT1F was correlated in an animal model of migraine (dural plasma protein extravasation model) leading to the development of lasmiditan. Lasmiditan is a newly approved acute treatment for migraine in the United States and is a lipophilic, highly selective 5-HT1F agonist that can cross the blood-brain barrier and act at peripheral nervous system (PNS) and central nervous system (CNS) sites. Lasmiditan activation of CNS-located 5-HT1F receptors (e.g., in the trigeminal nucleus caudalis) could potentially block the release of CGRP and the neurotransmitter glutamate, thus preventing and possibly reversing the development of central sensitization. Activation of 5-HT1F receptors in the thalamus can block secondary central sensitization of this region, which is associated with progression of migraine and extracephalic cutaneous allodynia. The 5-HT1F receptors are also elements of descending pain modulation, presenting another site where lasmiditan may alleviate migraine. There is emerging evidence that mitochondrial dysfunction might be implicated in the pathophysiology of migraine, and that 5-HT1F receptors can promote mitochondrial biogenesis. While the exact mechanism is unknown, evidence suggests that lasmiditan can alleviate migraine through 5-HT1F agonist activity that leads to inhibition of neuropeptide and neurotransmitter release and inhibition of PNS trigeminovascular and CNS pain signaling pathways.
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    Paclitaxel alters the evoked release of calcitonin gene-related peptide from rat sensory neurons in culture
    (Elsevier, 2014-03) Pittman, Sherry K.; Gracias, Neilia G.; Vasko, Michael R.; Fehrenbacher, Jill C.; Pharmacology and Toxicology, School of Medicine
    Peripheral neuropathy (PN) is a debilitating and dose-limiting side effect of treatment with the chemotherapeutic agent, paclitaxel. Understanding the effects of paclitaxel on sensory neuronal function and the signaling pathways which mediate these paclitaxel-induced changes in function are critical for the development of therapies to prevent or alleviate the PN. The effects of long-term administration of paclitaxel on the function of sensory neurons grown in culture, using the release of the neuropeptide calcitonin gene-related peptide (CGRP) as an endpoint of sensory neuronal function, were examined. Dorsal root ganglion cultures were treated with low (10 nM) and high (300 nM) concentrations of paclitaxel for 1, 3, or 5 days. Following paclitaxel treatment, the release of CGRP was determined using capsaicin, a TRPV1 agonist; allyl isothiocyanate (AITC), a TRPA1 agonist; or high extracellular potassium. The effects of paclitaxel on the release of CGRP were stimulant-, concentration-, and time-dependent. When neurons were stimulated with capsaicin or AITC, a low concentration of paclitaxel (10nM) augmented transmitter release, whereas a high concentration (300 nM) reduced transmitter release in a time-dependent manner; however, when high extracellular potassium was used as the evoking stimulus, all concentrations of paclitaxel augmented CGRP release from sensory neurons. These results suggest that paclitaxel alters the function of sensory neurons in vitro, and suggest that the mechanisms by which paclitaxel alters neuronal function may include functional changes in TRP channel activity. The described in vitro model will facilitate future studies to identify the signaling pathways by which paclitaxel alters neuronal sensitivity.
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    RET-DEPENDENT AND RET-INDEPENDENT MECHANISMS OF GFL-INDUCED ENHANCEMENT IN THE CAPSAICIN STIMULATED-RELEASE OF iCGRP FROM SENSORY NEURONS
    (2010-02-02T22:18:31Z) Schmutzler, Brian S.; Hingtgen, Cynthia M., 1966-; Cummins, Theodore R.; Vasko, Michael R.; Broustovetski, Nikolai; Hudmon, Andy
    The glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) are peptides implicated in the inflammatory response. They are released in increased amounts during inflammation and induce thermal hyperalgesia. Whether these molecules directly affect the sensitivity of primary nociceptive sensory neurons is unknown. This information could provide a link between increased inflammation-induced release of GFLs and their ability to promote inflammatory hyperalgesia. These molecules bind to one of four GFRα receptor subtypes, and this GFL-GFRα complex often translocates to the receptor tyrosine kinase, Ret. The focus of this dissertation was to determine whether GFLs modulate the stimulated-release of calcitonin gene-related peptide (CGRP). Isolated sensory neurons and freshly dissociated spinal cord tissue were used to examine the enhancement in stimulated-release of CGRP, a measure of sensitization. Exposure of isolated sensory neurons to GDNF, neurturin, and artemin, enhanced the capsaicin stimulated-release of immunoreactive CGRP (iCGRP). Sensitization by GFLs occurred in freshly dissociated spinal cord tissue. Persephin, another member of the GFL family, did not enhance stimulated-release of iCGRP. These results demonstrate that specific GFLs are mediators of neuronal sensitivity. The intracellular signaling pathways responsible for this sensitization were also evaluated. Inhibition of the mitogen activated protein kinase (MAPK)/extracellular signal-related kinase 1/2 (Erk 1/2) pathway selectively abolished the enhancement of CGRP release by GDNF. NTN-induced sensitization was abolished by inhibition of the phosphatidylinositol-3-kinase (PI-3K) pathway. Reduction in Ret abolished the GDNF-induced sensitization, but did not fully inhibit NTN or ART-induced sensitization. Inhibition of other cell surface receptors (neural cell adhesion molecule (NCAM), and Integrin β-1) had distinct effects on the sensitization capability of each of the GFLs. Ret and NCAM inhibition in combination abolished ART-induced sensitization. It was necessary to inhibit Ret, NCAM, and Integrin β-1 to prevent the NTN-induced sensitization. These data demonstrate that the GFLs use distinct signaling mechanisms to induce the sensitization of nociceptive sensory neurons. The work presented in this thesis provides the first evidence for these novel and distinct Ret-independent pathways for GFL-induced actions and provides insight into the mechanism of sensory neuronal sensitization in general.
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    Sensorimotor Activity Partially Ameliorates Pain and Reduces Nociceptive Fiber Density in the Chronically Injured Spinal Cord
    (Mary Ann Liebert, 2018-09-15) Sliwinski, Christopher; Nees, Timo A.; Puttagunta, Radhika; Weidner, Norbert; Blesch, Armin; Neurological Surgery, School of Medicine
    A large proportion of patients suffering from spinal cord injury (SCI) develop chronic central neuropathic pain. Previously, we and others have shown that sensorimotor training early after SCI can prevent the development of mechanical allodynia. To determine whether training initiated in the subchronic/chronic phase remains effective, correlates of below-level neuropathic pain were analyzed in the hindpaws 5-10 weeks after a moderate T11 contusion SCI (50 kDyn) in adult female C57BL/6 mice. In a comparison of SCI and sham mice 5 weeks post-injury, about 80% of injured animals developed mechanical hypersensitivity to light mechanical stimuli, whereas testing of noxious stimuli revealed hypo-responsiveness. Thermal sensitivity testing showed a decreased response latency after injury. Without intervention, mechanical and thermal hyper-responsiveness were evident until the end of the experiment (10 weeks). In contrast, treadmill training (2 × 15 min/day; 5 × /week) initiated 6 weeks post-injury resulted in partial amelioration of pain behavior and this effect remained stable. Analysis of calcitonin gene-related peptide (CGRP)-labeled fibers in lamina III-IV of the lumbar dorsal horn revealed an increase in labeling density after SCI. This was not due to changes in the number or size distribution of CGRP-labeled lumbar dorsal root ganglion neurons. Treadmill training reduced the CGRP-labeling density in the spinal cord of injured mice, whereas the density of non-peptidergic isolectin-B4 (IB4)+ fibers showed no changes in lamina IIi and a slight reduction of sparse IB4 labeling in laminae III-IV. Thus, sensorimotor activity initiated in the subchronic/chronic phase of SCI remains effective in ameliorating pain behavior and influencing structural changes of the nociceptive system.