title: Mobilisation of intracellular Ca2+ by mGluR5 metabotropic glutamate receptor activation in neonatal rat cultured dorsal root ganglia neurones.
abstract: The ability of metabotropic glutamate receptor activation to mobilise intracellular calcium was investigated in cultured dorsal root ganglion (DRG) neurones from neonatal rats using the calcium sensitive fluorescent dye Fura-2. L-glutamate (10 microM) caused sustained and oscillatory increases in intracellular calcium concentration ([Ca2+]i) in a subpopulation of cultured DRG neurones. The oscillatory responses were not blocked by combined application of the ionotropic glutamate receptor antagonists MK 801 (2 microM) and CNQX (20 microM). Oscillations in [Ca2+]i were also observed following application of the nonselective metabotropic glutamate receptor (mGluR) agonist, trans-(1S,3R)-1-aminocyclopentane-1S, 3R-dicarboxylic acid (1S,3R)-ACPD, 20 microM) and the mGluR5 agonist (RS)-2-chloro-5-hydroxyphenylglycine (CHPG, 500 microM). These responses were blocked by the selective Group I mGluR antagonist (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA) (100 microM) and Ca2+ release channel inhibitors ryanodine (100 microM) and dantrolene (10 microM). The predominantly Group II agonist (2S,2'R,3'R)-2-(2'3'-dicarboxy-cyclopropyl)glycine (DCG-IV, 100 microM) failed to produce Ca2+ transients alone but suppressed responses to CHPG. Reverse transcriptase PCR techniques, using primers specific to Group I mGluRs, revealed the presence of mGluR5 but not mGluR1 mRNA in these cells. Therefore, glutamate can cause a slowly activating and reversible mobilisation of [Ca2+]i in sensory neurones by activation of ionotropic receptors, and can induce oscillatory calcium transients by selectively activating metabotropic glutamate receptors that are likely to be of the mGluR5 subtype.
authors.affiliation: Merck Sharp & Dohme Neuroscience Research Centre, Harlow, UK.
authors.forename: J H
authors.initials: JH
authors.lastname: Crawford
authors.forename: A
authors.initials: A
authors.lastname: Wainwright
authors.forename: R
authors.initials: R
authors.lastname: Heavens
authors.forename: J
authors.initials: J
authors.lastname: Pollock
authors.forename: D J
authors.initials: DJ
authors.lastname: Martin
authors.forename: R H
authors.initials: RH
authors.lastname: Scott
authors.forename: G R
authors.initials: GR
authors.lastname: Seabrook
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002478:Cells, Cultured; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D003521:Cyclopropanes / Q000494:pharmacology; D003620:Dantrolene / Q000494:pharmacology; D005453:Fluorescence; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism*; D018698:Glutamic Acid / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D007189:Indans; D010648:Phenylacetates / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012433:Ryanodine / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects; D013237:Stereoisomerism
chemical_list: C095756:1-aminoindan-1,5-dicarboxylic acid; C107349:2-chloro-5-hydroxyphenylglycine; D002121:Calcium Channel Blockers; D003521:Cyclopropanes; C578937:Grm5 protein, rat; D007189:Indans; D010648:Phenylacetates; D012333:RNA, Messenger; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D019837:Ryanodine Receptor Calcium Release Channel; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; C082313:2-(2,3-dicarboxycyclopropyl)glycine; D012433:Ryanodine; D018698:Glutamic Acid; D003620:Dantrolene; D002118:Calcium; D005998:Glycine