title: Role of intracellular calcium stores on the effect of metabotropic glutamate receptors on phosphorylation of glial fibrillary acidic protein in hippocampal slices from immature rats.
abstract: Phosphorylation of glial fibrillary acidic protein (GFAP) in slices from immature rats is stimulated by glutamate via a group II metabotropic glutamate receptor (mGluR II) and by absence of external Ca2+ in reactions that are not additive (Wofchuk and Rodnight, Neurochem. Int. 24:517-523, 1994). These observations suggested that glutamate, via an mGluR, inhibits Ca(2+)-entry through L-type Ca2+ channels and down-regulates a Ca(2+)-dependent dephosphorylation event coupled to GFAP. Because ryanodine receptors are present on internal Ca2+ stores and are associated with L-type Ca(2+)-channels, we investigated the possibility that the glutamatergic modulation of GFAP phosphorylation involves internal Ca2+ stores regulated by ryanodine receptors and whether the Ca2+ originating from these stores acts in a similar manner to external Ca2+. The results showed that the ryanodine receptor-agonists, caffeine and ryanodine and thapsigargin, all of which in appropriate doses increase cytoplasmic Ca2+, reversed the stimulation of GFAP phosphorylation given by 1S,3R-ACPD, an mGluR II agonist.
authors.affiliation: Departamento de Bioquimica, Instituto de Ciências Básicas da Saúde, UFRGS, Porto Alegre, RS, Brazil.
authors.forename: D
authors.initials: D
authors.lastname: Oppelt
authors.forename: R
authors.initials: R
authors.lastname: Rodnight
authors.forename: J
authors.initials: J
authors.lastname: Horn
authors.forename: D
authors.initials: D
authors.lastname: Fitarelli
authors.forename: T
authors.initials: T
authors.lastname: Kommers
authors.forename: D
authors.initials: D
authors.lastname: Oliveira
authors.forename: S
authors.initials: S
authors.lastname: Wofchuk
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000502:physiology*; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000633:toxicity; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D066298:In Vitro Techniques; D009498:Neurotoxins / Q000633:toxicity; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism*
chemical_list: D005904:Glial Fibrillary Acidic Protein; D009498:Neurotoxins; D010710:Phosphates; D018094:Receptors, Metabotropic Glutamate; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; D002118:Calcium