Increased perinuclear Ca2+ activity evoked by metabotropic glutamate receptor activation in rat hippocampal neurones.
1. The effect of metabotropic glutamate receptor activation on intracellular Ca2+ activity (alpha Cai) of rat hippocampal pyramidal neurones in vitro was examined using ratiometric confocal laser scanning microscopy with the Ca(2+)-sensitive fluorescent probe indo-1 AM. 2. Metabotropic receptors were selectively activated with 1S,3R-1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD; 100 microM) in the presence of D-2-amino 5-phosphonovaleric acid (D-APV), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and CdCl2. Most pyramidal neurones (77/84) responded with an elevation in Ca2+ activity, maximal after 3-5 min. Fluorescence ratio responses were concentration dependent (EC50 approximately 10 microM) and were blocked by prior application of the antagonist (RS)-4-carboxy-3-hydroxyphenylglycine (RS-CHPG, 300 microM). 3. Responses to 1S,3R-ACPD (100 microM) also caused acidification of the neurones, from estimated control pH 7.2 to pH 6.6 (measured with the pH-sensitive dye SNAFL-calcein). The correction factor for indo-1 determination of Ca2+ was estimated to be x 1.4. 4. Elevations in alpha Cai were greater within the perinuclear region (> 1000 nM), than in the cytoplasm (approximately 200 nM). This region was devoid of staining by the endoplasmic reticulum staining dye 3,3'-dihexyloxacarbocyanine iodide (DiOC6(3)). 5. It is concluded that activation of metabotropic receptors in immature rat hippocampal pyramidal neurones leads to a large increase in perinuclear Ca2+ which would be well positioned to interact with the genome.
Phenna
S
S
Department of Physiology and Pharmacology, University of Southampton, UK.
Jane
S D
SD
Chad
J E
JE
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003515:Cycloleucine / Q000031:analogs & derivatives / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D018613:Microscopy, Confocal; D009474:Neurons / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D009498:Neurotoxins / Q000494:pharmacology; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism*
D018690:Excitatory Amino Acid Agonists; D005456:Fluorescent Dyes; D009498:Neurotoxins; D018094:Receptors, Metabotropic Glutamate; D003515:Cycloleucine; C049925:fura-2-am; C036361:1-amino-1,3-dicarboxycyclopentane; D002118:Calcium; D016257:Fura-2