Group I metabotropic glutamate receptor-mediated calcium signalling and immediate early gene expression in cultured rat striatal neurons

Eur J Neurosci. 2003 Feb;17(4):741-50. doi: 10.1046/j.1460-9568.2003.02495.x.

Abstract

Group I metabotropic glutamate receptors (mGluRs) are positively coupled to phospholipase C (PLC) via Galphaq-proteins and are expressed in the medium-sized projection neurons of striatum. To characterize the group I mGluR/PLC-sensitive modulation of intracellular Ca2+ ([Ca2+]i) signalling, primary neuronal cultures were prepared from the striatum of E19 rat embryos or neonatal day-1 rat pups. Cytoplasmic Ca2+ signals were examined with fura-2/AM at a signal cell level. After 17-18 days in culture, a profound Ca2+ response consisting of two phases was induced in cultured striatal neurons following bath application of the selective group I agonist, 3,5-dihydroxyphenylglycine (DHPG). The [Ca2+]i elevation was concentration- and time-dependent, and was blocked by coexposure to the group I antagonist, N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC), or the PLC inhibitor, U-73122, but not to the group II/III antagonist (RS)-alpha-methylserine-O-phosphate monophenyl ester (MSOPPE). A series of further pharmacological studies demonstrated that the initial spike-like transient was dependent on intracellular Ca2+ mobilization through 1,4,5-triphosphate-sensitive stores, and the second long-lasting rise was dependent on extracellular Ca2+ influx through N-methyl-d-aspartate (NMDA) receptors and especially L-type voltage-operated Ca2+ channels. Lastly, using an immediate early gene c-fos as a report of inducible gene expression, the resultant [Ca2+]i elevation contributes to DHPG-stimulated c-fos mRNA and Fos protein expression in striatal neurons as revealed by quantitative in situ hybridization and immunocytochemistry, respectively. These results demonstrate that group I mGluRs are able to affect Ca2+ homeostasis at multiple levels and trigger Ca2+-sensitive gene transcription in striatal neurons.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Animals, Newborn
  • Benzopyrans / pharmacology
  • Calcium Channel Blockers / pharmacology
  • Calcium Signaling / physiology*
  • Cell Count
  • Cells, Cultured
  • Corpus Striatum / cytology*
  • Corpus Striatum / drug effects
  • Dose-Response Relationship, Drug
  • Drug Interactions
  • Embryo, Mammalian
  • Enzyme Inhibitors / pharmacology
  • Fura-2 / metabolism
  • Gene Expression / drug effects
  • Gene Expression / physiology*
  • Genes, fos / genetics
  • Immediate-Early Proteins
  • Immunohistochemistry / methods
  • In Situ Hybridization / methods
  • Methoxyhydroxyphenylglycol / analogs & derivatives*
  • Methoxyhydroxyphenylglycol / pharmacology
  • Neurons / drug effects
  • Neurons / metabolism*
  • Nifedipine / pharmacology
  • Proto-Oncogene Proteins c-fos / metabolism
  • Rats
  • Receptors, Metabotropic Glutamate / agonists
  • Receptors, Metabotropic Glutamate / antagonists & inhibitors
  • Receptors, Metabotropic Glutamate / physiology*
  • Ryanodine / pharmacology
  • Time Factors

Substances

  • Benzopyrans
  • Calcium Channel Blockers
  • Enzyme Inhibitors
  • Immediate-Early Proteins
  • N-phenyl-7-(hydroxyimino)cyclopropa(b)chromen-1a-carboxamide
  • Proto-Oncogene Proteins c-fos
  • Receptors, Metabotropic Glutamate
  • metabotropic glutamate receptor type 1
  • Ryanodine
  • Methoxyhydroxyphenylglycol
  • Nifedipine
  • Fura-2
  • 3,4-dihydroxyphenylglycol