title: Group I metabotropic glutamate receptor-mediated calcium signalling and immediate early gene expression in cultured rat striatal neurons.
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.
authors.affiliation: Department of Pharmacology, School of Pharmacy, University of Missouri-Kansas City, 2411 Holmes Street, Rm M3-C225, Kansas City, Missouri 64108, USA.
authors.forename: Limin
authors.initials: L
authors.lastname: Mao
authors.forename: John Q
authors.initials: JQ
authors.lastname: Wang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001578:Benzopyrans / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000502:physiology*; D002452:Cell Count; D002478:Cells, Cultured; D003342:Corpus Striatum / Q000166:cytology* / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016257:Fura-2 / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology*; D016762:Genes, fos / Q000235:genetics; D017874:Immediate-Early Proteins; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives* / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000502:physiology*; D012433:Ryanodine / Q000494:pharmacology; D013997:Time Factors
chemical_list: D001578:Benzopyrans; D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D017874:Immediate-Early Proteins; C442478:N-phenyl-7-(hydroxyimino)cyclopropa(b)chromen-1a-carboxamide; D016760:Proto-Oncogene Proteins c-fos; D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1; D012433:Ryanodine; D008734:Methoxyhydroxyphenylglycol; D009543:Nifedipine; D016257:Fura-2; C010117:3,4-dihydroxyphenylglycol