title: Modulation of neurite outgrowth by activation of calcium-permeable kainate receptors expressed by rat nociceptive-like dorsal root ganglion neurons.
abstract: Neurite outgrowth is a fundamental step in establishing proper neuronal connections in the developing central nervous system. Dynamic control of outgrowth has been attributed to changes in growth cone Ca2+ levels in response to extracellular cues. Here we have investigated a possible role for Ca2+ permeable kainate (KA) receptors in regulating neurite outgrowth of nociceptive-like dorsal root ganglion (DRG) neurons. To identify KA receptor subunits likely to be involved, we used quantitative RT-PCR on acutely dissociated DRG and dorsal horn neurons. DRG neurons expressed more GluK1, particularly the GluK1b spice variant, than dorsal horn neurons. Conversely, dorsal horn neurons expressed more GluK2, particularly GluK2a, than DRG neurons. Further, an RNA editing assay indicated that the majority of GluK1 and GluK2 mRNA transcripts in DRG were unedited. Imaging Ca2+ transients following application of a KA receptor agonist to DRG and dorsal horn co-cultures revealed increases in intracellular Ca2+ in the growth cones of DRG neurons. In the majority of cases, this increase in Ca2+ was partly or completely blocked by Joro spider toxin (JSTX), an antagonist for Ca2+-permeable AMPA and KA receptors. Treatment of DRG/dorsal horn co-cultures with KA for 18 hours suppressed neurite outgrowth while application of the rapidly desensitizing KA receptor agonist SYM 2081, the competitive AMPA/KA receptor antagonist, CNQX, and JSTX or philanthotoxin enhanced neurite outgrowth and prevented KA effects on neurite outgrowth. Thus, Ca2+ entry through KA receptors at the growth cone of DRG neurons may be an important regulator of neurite outgrowth.
authors.affiliation: Department of Neuroscience, Program in Neurobiology and Behavior, Columbia University, New York, New York 10032, USA.
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Joseph
authors.forename: Damian J
authors.initials: DJ
authors.lastname: Williams
authors.forename: Amy B
authors.initials: AB
authors.lastname: MacDermott
mesh_terms: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000243:Adenosine Deaminase / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004622:Embryo, Mammalian; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019922:GAP-43 Protein / Q000378:metabolism; D005727:Ganglia, Spinal / Q000166:cytology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D005971:Glutamates / Q000494:pharmacology; D020439:Growth Cones / Q000187:drug effects / Q000502:physiology; D007608:Kainic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D016501:Neurites / Q000187:drug effects / Q000502:physiology*; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology; D017393:RNA Editing / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018092:Kainic Acid Receptors / Q000235:genetics / Q000378:metabolism*; D011984:Sensory Receptor Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D013111:Spider Venoms / Q000494:pharmacology; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D000097806:GluK2 Kainate Receptor
chemical_list: D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000243:Adenosine Deaminase; D002118:Calcium; D018691:Excitatory Amino Acid Antagonists; D019922:GAP-43 Protein; D005971:Glutamates; D007608:Kainic Acid; D008565:Membrane Proteins; D009467:Neuromuscular Depolarizing Agents; D012333:RNA, Messenger; D018092:Kainic Acid Receptors; D013111:Spider Venoms; D000097806:GluK2 Kainate Receptor; C044936:JSTX spider toxin; C046105:4-methylglutamic acid; C548484:Ada protein, rat; C012301:domoic acid