Depletion of calcium stores in injured sensory neurons: anatomic and functional correlates. Anesthesiology 2009 Aug;111(2):393-405
Date
07/16/2009Pubmed ID
19602957Pubmed Central ID
PMC2885290DOI
10.1097/ALN.0b013e3181ae63b0Scopus ID
2-s2.0-68249135303 (requires institutional sign-in at Scopus site) 15 CitationsAbstract
BACKGROUND: Painful nerve injury leads to disrupted Ca signaling in primary sensory neurons, including decreased endoplasmic reticulum (ER) Ca storage. This study examines potential causes and functional consequences of Ca store limitation after injury.
METHODS: Neurons were dissociated from axotomized fifth lumbar (L5) and the adjacent L4 dorsal root ganglia after L5 spinal nerve ligation that produced hyperalgesia, and they were compared to neurons from control animals. Intracellular Ca levels were measured with Fura-2 microfluorometry, and ER was labeled with probes or antibodies. Ultrastructural morphology was analyzed by electron microscopy of nondissociated dorsal root ganglia, and intracellular electrophysiological recordings were obtained from intact ganglia.
RESULTS: Live neuron staining with BODIPY FL-X thapsigargin (Invitrogen, Carlsbad, CA) revealed a 40% decrease in sarco-endoplasmic reticulum Ca-ATPase binding in axotomized L5 neurons and a 34% decrease in L4 neurons. Immunocytochemical labeling for the ER Ca-binding protein calreticulin was unaffected by injury. Total length of ER profiles in electron micrographs was reduced by 53% in small axotomized L5 neurons, but it was increased in L4 neurons. Cisternal stacks of ER and aggregation of ribosomes occurred less frequently in axotomized neurons. Ca-induced Ca release, examined by microfluorometry with dantrolene, was eliminated in axotomized neurons. Pharmacologic blockade of Ca-induced Ca release with dantrolene produced hyperexcitability in control neurons, confirming its functional importance.
CONCLUSIONS: After axotomy, ER Ca stores are reduced by anatomic loss and possibly diminished sarco-endoplasmic reticulum Ca-ATPase. The resulting disruption of Ca-induced Ca release and protein synthesis may contribute to the generation of neuropathic pain.
Author List
Gemes G, Rigaud M, Weyker PD, Abram SE, Weihrauch D, Poroli M, Zoga V, Hogan QHAuthors
Quinn H. Hogan MD Professor in the Anesthesiology department at Medical College of WisconsinDorothee Weihrauch DVM, PhD Research Scientist II in the Anesthesiology department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
AnimalsBoron Compounds
Calbindin 2
Calcium
Calcium Signaling
Cytoplasm
Dantrolene
Electrophysiology
Endoplasmic Reticulum
Fluorescent Dyes
Hyperalgesia
Immunohistochemistry
Ligation
Male
Microscopy, Electron
Pain Measurement
Rats
Rats, Sprague-Dawley
S100 Calcium Binding Protein G
Sensory Receptor Cells
Spinal Nerves
