title: Muscarinic receptors in human SH-SY5Y neuroblastoma cell line: regulation by phorbol ester and retinoic acid-induced differentiation.
abstract: The specific binding of the muscarinic ligand [3H](-)quinuclidinyl benzilate [( 3H]QNB) to cell membranes of human SH-SY5Y neuroblastoma cells was studied. Saturation isotherms yielded a Kd = 0.28 +/- 0.06 nM and a Bmax of 337 +/- 47 pmol/g protein. Pirenzepine inhibited [3H]QNB binding; inhibition data showed best fit to a 2-site binding model revealing both a high affinity pirenzepine site (34%, KH = 10 nM) and a low affinity site (66%, KL = 1 microM). These results indicate that muscarinic receptors on SH-SY5Y cells may be subclassified as M1/M2 subtypes. Morphological and biochemical differentiation of these cells after treatment with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) or retinoic acid (RA) resulted in a decrease and an increase in the number of muscarinic binding sites, respectively. Furthermore, TPA- and RA-treated cells showed a significant increase in acetylcholinesterase activity compared with non-treated cells. However, only RA-treated cells showed significant increase in choline acetyltransferase activity compared to non-treated cells. These findings demonstrate that TPA and RA can regulate both the number of muscarinic receptors and the acetylcholinesterase activity in human SH-SY5Y neuroblastoma cells.
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D001285:Atropine / Q000378:metabolism; D001667:Binding, Competitive; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002795:Choline O-Acetyltransferase / Q000378:metabolism; D006801:Humans; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D010890:Pirenzepine / Q000378:metabolism; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000187:drug effects* / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D011976:Receptors, Muscarinic; D010890:Pirenzepine; D014212:Tretinoin; D011813:Quinuclidinyl Benzilate; D001285:Atropine; D002795:Choline O-Acetyltransferase; D000110:Acetylcholinesterase; D013755:Tetradecanoylphorbol Acetate