carbocyanines and Pain

The birth of small-diameter TrkA+ neurons that mediate pain and thermoreception begins approximately 24 hours after the cessation of neural crest cell migration from progenitors residing in the nascent dorsal root ganglion. Although multiple geographically distinct progenitor pools have been proposed, this study is the first to comprehensively characterize the derivation of small-diameter neurons. In the developing chick embryo we identify novel patterns in neural crest cell migration and colonization that sculpt the incipient ganglion into a postmitotic neuronal core encapsulated by a layer of proliferative progenitor cells. Furthermore, we show that this outer progenitor layer is composed of three spatially, temporally, and molecularly distinct progenitor zones, two of which give rise to distinct populations of TrkA+ neurons.

Topics: Animals; Biomarkers; Body Patterning; Carbocyanines; Cell Differentiation; Cell Movement; Cell Proliferation; Cell Size; Chick Embryo; Functional Laterality; Ganglia, Spinal; Immunohistochemistry; Nerve Tissue Proteins; Neural Crest; Neuroanatomical Tract-Tracing Techniques; Neurogenesis; Nociceptors; Organ Culture Techniques; Pain; Receptor, trkA; RNA, Messenger; Sensory Receptor Cells; Stem Cells; Thermosensing

DNA array analysis of dorsal root ganglion (DRG) using a rat model with nerve root constriction.. To determine the molecular changes in the DRG adjacent to the injured nerve root in a lumbar radiculopathy model.. DNA array analysis in lumbar radiculopathy model has so far focused on the spinal dorsal horn. The molecular changes in the DRG adjacent to the injured nerve root in lumbar radiculopathy remain to be determined.. Bilateral L5 DRGs were removed from 12 Sprague-Dawley rats on days 2, 7, 14, and 21 after nerve root ligation and on day 7 from 3 rats with sham operation. The aRNAs from the DRGs with nerve root ligation were labeled with Cy5 dye and those from the opposite side DRG (control) were labeled with Cy3 dye, and then hybridized to a 7793-spot Panorama Micro Array. It was considered to be significantly upregulated, when an average expression ratio of Cy5 to Cy3 was 2 or more. Genes upregulated were classified into early phase group (upregulated on day 2), midphase group (upregulated on days 7 and 14), and continuous group (upregulated from day 2 to 21). Seventeen genes were subjected to validation analysis with real-time quantitative PCR.. There were 16 upregulated genes in the early phase group, 56 genes in the midphase group, and 17 genes in the continuous group. Functional categorization revealed dominantly upregulated gene categories in each group; transcription/translation in the early phase group, enzyme/metabolism in the midphase group, and structure in the continuous group. Validation analysis of 17 genes demonstrated mean relative expression of 2.0 or more in all but 1 gene in the DRGs with nerve root ligation and none of them in the DRGs with sham operation.. The genes identified in this study, especially those involved in pain signaling and inflammation, serve as potential targets for molecular-based therapy for lumbar radiculopathy.

Topics: Animals; Carbocyanines; Disease Models, Animal; Fluorescent Dyes; Ganglia, Spinal; Gene Expression; Gene Expression Profiling; Lumbar Vertebrae; Male; Oligonucleotide Array Sequence Analysis; Pain; Radiculopathy; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Spinal Nerve Roots; Time Factors; Up-Regulation

Talpid moles are small insectivores that live in dark underground tunnels. They depend heavily on touch to navigate and find food. Most species have an array of complex epidermal sensory structures called Eimer's organs that cover the tip of the nose. In this study, the anatomy of Eimer's organ was examined in the coast mole and star-nosed mole by using the fluorescent styryl pyridinium dye AM1-43 and immunocytochemical staining for neurofilament 200 and substance P. In addition, DiI was used to label neural components of Eimer's organ. AM1-43 labeled all of the Eimer's organ receptors after systemic injection, suggesting a role in mechanotransduction. Immunostaining with neurofilament 200 and substance P labeled distinct subtypes of sensory fibers. Substance P labeled a group of free nerve endings along the outer edge of Eimer's organ, indicating a nociceptive role for these fibers. In contrast, neurofilament 200 labeled a more central set of nerve endings, suggesting that these fibers function as low-threshold mechanoreceptors. By labeling subsets of trigeminal afferents distant from the receptor array with DiI, we revealed innervation patterns indicating that one afferent supplies the outer, substance P-positive set of free nerve endings, whereas several afferents differentially innervate the central free nerve endings. Our results suggest that the free nerve endings innervating Eimer's organ are largely mechanosensitive and may play an important role in the rapid sensory discrimination observed in these species.

Topics: Afferent Pathways; Animals; Carbocyanines; Fluorescent Dyes; Immunohistochemistry; Merkel Cells; Moles; Nerve Endings; Nerve Fibers; Neurofilament Proteins; Pain; Pyridinium Compounds; Quaternary Ammonium Compounds; Substance P; Touch

Erythropoietin (Epo) has been shown to have potent anti-apoptotic activity in central nervous system neurons in animal models of ischaemic injury. Recently, Epo and its receptor (EpoR) have been identified in the peripheral nervous system [Campana & Myers (2001), FASEB J., 15, 1804-1806]. Herein, we demonstrate that in painful neuropathy caused by L5 spinal nerve crush (SNC), therapy with recombinant human Epo (rhEpo) reduced dorsal root ganglion (DRG) apoptosis and pain behaviours. Quantification of both DRG neurons and satellite cells revealed that vehicle-treated, crush-injured DRGs had 35.5 +/- 8.3% apoptotic neurons and 23.5 +/- 2.36% satellite cells compared with 7.5 +/- 6.3% apoptotic neurons and 6.4 +/- 3.94% satellite cells in rhEpo-treated, crush-injured DRGs (P < 0.05). While rhEpo-treated animals were not initially protected from mechanical allodynia associated with L5 SNC, rhEpo did significantly improve recovery rates compared to vehicle-treated animals (P < 0.01). Systemic rhEpo therapy increased JAK2 phosphorylation, a key anti-apoptotic signalling molecule for Epo-induced neuroprotection, in DRGs after crush. Dual immunofluorescence demonstrated Epo-induced JAK2-p was associated with both neuronal and glial cells. JAK2-p was associated with NF200-positive large neurons and with smaller neurons. This population of small neurons did not colocalize with IB4, a marker of nonpeptidergic, glial derived growth factor-responsive neurons. The findings link anti-apoptosis activities of Epo/EpoR/JAK2 in DRG neurons capable of inducing protracted pain states with reductions in pain behaviours, and therefore support a role for Epo therapy in the treatment of neuropathic pain.

Topics: Animals; Apoptosis; Behavior, Animal; Blotting, Western; Carbocyanines; Cell Count; Disease Models, Animal; Dose-Response Relationship, Drug; Erythropoietin; Female; Fluorescent Antibody Technique; Functional Laterality; Ganglia, Spinal; Glial Fibrillary Acidic Protein; Humans; Hyperalgesia; In Situ Nick-End Labeling; Janus Kinase 2; Microscopy, Confocal; Neurofilament Proteins; Pain; Pain Measurement; Pain Threshold; Peripheral Nervous System Diseases; Plant Lectins; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Rats; Rats, Sprague-Dawley; Ribosome Inactivating Proteins; Satellite Cells, Perineuronal; Time Factors

DiI-labeled colon sensory neurons were acutely dissociated from S1 rat dorsal root ganglia (DRG) and studied using perforated whole cell patch-clamp techniques. Forty-six percent (54/116) of labeled sensory neurons responded to capsaicin (10(-8)- 10(-5) M) with an increase in inward current, which was a nonspecific cation conductance. Responses to capsaicin applied by puffer ejection were dependent on dose, with a half-maximal response at 4.9 x 10(-7) M; bath application was characterized by marked desensitization. Voltage-gated Na(+) currents in 23 of 30 DRG cells exhibited both TTX-sensitive and TTX-resistant components. In these cells, capsaicin induced an inward current in 11 of 17 cells tested. Of the cells containing only a TTX-sensitive component, none of six cells tested was sensitive to capsaicin. In all cells that responded to capsaicin with an increase in inward current, capsaicin abolished voltage-gated Na(+) currents (n = 21). Capsazepine (10(-6) M) significantly attenuated both the increase in inward current and the reduction in Na(+) currents. Na(+) currents were not significantly altered by adenosine, bradykinin, histamine, PGE(2), or serotonin at 10(-6) M and 10(-5) M. These findings may have important implications for understanding both the irritant and analgesic properties of capsaicin.

Topics: Action Potentials; Adenosine; Analgesics; Animals; Bradykinin; Capsaicin; Carbocyanines; Colon; Dinoprostone; Dose-Response Relationship, Drug; Electrophysiology; Fluorescent Dyes; Ganglia, Spinal; Histamine; Ion Channel Gating; Male; Neurons, Afferent; Pain; Rats; Rats, Sprague-Dawley; Serotonin; Sodium; Sodium Channels; Tetrodotoxin

Angioleiomyoma is frequently painful and the cause of the pain is unknown. The purpose of this study was to compare the mast cell population and innervation of painful and painless angioleiomyomas. Twenty-four cases of angioleiomyoma were examined; 16 painful and 8 painless cases. Pinacyanol erythrosinate and antibodies to protein gene product (PGP) 9.5 were used to demonstrate mast cells and nerves respectively. PGP 9.5-immunoreactive nerve fibres were found in most of the painful (13/16 cases) and painless lesions (5/8). Mast cells were not seen in half of the painful lesions but were seen in most of the painless lesions (7/8). The median mast cell density was 1.1 cells/mm2 for the painful lesions and 21.9 cells/mm2 for the painless lesions (P = 0.048, Mann-Whitney test). The lower mast cell density in the painful lesions may reflect increased mast cell degranulation. It is proposed that neural and vascular events, similar to those occurring in the triple response to mild cutaneous injury, may produce pain in angioleiomyoma and other painful skin tumours.

Topics: Carbocyanines; Erythrosine; Hemangioma; Humans; Immunoenzyme Techniques; Leiomyoma; Mast Cells; Nerve Fibers; Pain; Skin Neoplasms; Thiolester Hydrolases; Ubiquitin Thiolesterase