Increased perinuclear Ca²⁺ activity evoked by metabotropic glutamate receptor activation in rat hippocampal neurones

Phenna, S., Jane, S.D. and Chad, J.E. (1995) Increased perinuclear Ca²⁺ activity evoked by metabotropic glutamate receptor activation in rat hippocampal neurones. Journal of Physiology, 486 (Pt 1), 149-161.

Abstract

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 Ca²⁺-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 µM) 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 µM) and were blocked by prior application of the antagonist (RS)-4-carboxy-3-hydroxyphenylglycine (RS-CHPG, 300 µM). 3. Responses to 1S,3R-ACPD (100 µM) 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.

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Contributors

Author: J.E. Chad

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