Mobilisation of intracellular Ca2+ by mGluR5 metabotropic glutamate receptor activation in neonatal rat cultured dorsal root ganglia neurones

• Published in: Neuropharmacology Vol. 39; no. 4; pp. 621 - 630
• Main Authors: CRAWFORD, J. H, WAINWRIGHT, A, HEAVENS, R, POLLOCK, J, MARTIN, D. J, SCOTT, R. H, SEABROOK, G. R
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier 14.02.2000
• Subjects: Aminoacid receptors (glycine, glutamate, gaba); Animals; Animals, Newborn; Biological and medical sciences; Calcium - metabolism; Calcium Channel Blockers - pharmacology; Cell receptors; Cell structures and functions; Cells, Cultured; Cycloleucine - analogs & derivatives; Cycloleucine - pharmacology; Cyclopropanes - pharmacology; Dantrolene - pharmacology; Fluorescence; Fundamental and applied biological sciences. Psychology; Ganglia, Spinal - cytology; Ganglia, Spinal - metabolism; Glutamic Acid - pharmacology; Glycine - analogs & derivatives; Glycine - pharmacology; Indans; Molecular and cellular biology; Phenylacetates - pharmacology; Rats; Rats, Sprague-Dawley; Rats, Wistar; Receptor, Metabotropic Glutamate 5; Receptors, Metabotropic Glutamate - agonists; Receptors, Metabotropic Glutamate - antagonists & inhibitors; Receptors, Metabotropic Glutamate - metabolism; Receptors, Metabotropic Glutamate - physiology; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; Ryanodine - pharmacology; Ryanodine Receptor Calcium Release Channel - drug effects; Stereoisomerism; Ionotropic receptor; Agonist; Rat; Rodentia; Glutamate receptor; Gene expression; Glutamate; Subunit; In vitro; Ganglion neuron; Vertebrata; Mammalia; Calcium ion; Structure activity relation; Metabotropic receptor; Newborn animal; Antagonist
• ISSN: 0028-3908; 1873-7064
• DOI: 10.1016/S0028-3908(99)00167-7

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.