title: Inositol 1,4,5-trisphosphate receptor immunoreactivity in SH-SY5Y human neuroblastoma cells is reduced by chronic muscarinic receptor activation.
abstract: Inositol 1,4,5-trisphosphate (InsP3) receptor immunoreactivity in SH-SY5Y human neuroblastoma cells was monitored with a monoclonal antibody raised against the mouse cerebellar InsP3 receptor. Recognition of a protein corresponding to the InsP3 receptor (molecular mass, approximately 275 kDa) was inhibited markedly following exposure of cells to 0.1 mM carbachol. This effect was half-maximal and maximal at approximately 2 and approximately 6 h, respectively; was blocked by atropine; but was not mimicked by thapsigargin, K+, or phorbol 12-myristate 13-acetate. However, the decrease in immunoreactivity following exposure of cells to carbachol for 5 h was blocked if the extracellular Ca2+ concentration was reduced from 1.3 mM to 200 nM. This manipulation also reduced markedly carbachol-induced increases in InsP3 concentration at 5 h. These data indicate that chronic muscarinic stimulation of phosphoinositide hydrolysis reduces InsP3 receptor concentration in SH-SY5Y cells, perhaps via a mechanism that involves prolonged elevation of InsP3 levels.
authors.affiliation: Department of Pharmacology and Therapeutics, University of Leicester, England.
authors.forename: R J
authors.initials: RJ
authors.lastname: Wojcikiewicz
authors.forename: S
authors.initials: S
authors.lastname: Nakade
authors.forename: K
authors.initials: K
authors.lastname: Mikoshiba
authors.forename: S R
authors.initials: SR
authors.lastname: Nahorski
mesh_terms: D000911:Antibodies, Monoclonal; D015220:Calcium Channels; D002217:Carbachol / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D006531:HEPES; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D009994:Osmolar Concentration; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D011976:Receptors, Muscarinic / Q000502:physiology*; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D015220:Calcium Channels; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D011976:Receptors, Muscarinic; D004533:Egtazic Acid; D002217:Carbachol; D006531:HEPES