title: Expression and agonist-induced down-regulation of mRNAs of m2- and m3-muscarinic acetylcholine receptors in cultured cerebellar granule cells.
abstract: The regulation and expression of muscarinic acetylcholine receptor (mAChR) mRNA was studied in cultured cerebellar granule cells using Northern blot hybridization, mRNA species for m2- and m3-mAChRs but not m1- and m4-mAChRs were detected in these cells. The expression of mRNAs of both m2- and m3-mAChRs reached a maximum on the tenth day in culture but their expression patterns differed. Treatment of cerebellar granule cells after 8 days in culture with 100 microM carbachol led to differential down-regulation of the mRNA species of both mAChR subtypes present. Muscarinic receptor antagonists, atropine (1 microM) and pirenzepine (10 microM), prevented carbachol-induced m3-mAChR mRNA down-regulation observed at 8 h. However, exposure to either atropine or pirenzepine alone for 8 h led to a significant up-regulation of m3-mAChR mRNA. Thus, the mRNA species for both m2- and m3-mAChR subtypes are differentially expressed in culture and down-regulated by agonist stimulation. The loss of these mRNA species may play a role in the down-regulation of mAChR binding sites that occurs after desensitization.
authors.affiliation: Unit on Molecular Neurobiology, National Institute of Mental Health, Bethesda, Maryland 20892.
authors.forename: F
authors.initials: F
authors.lastname: Fukamauchi
authors.forename: C
authors.initials: C
authors.lastname: Hough
authors.forename: D M
authors.initials: DM
authors.lastname: Chuang
mesh_terms: D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D002531:Cerebellum / Q000378:metabolism*; D015342:DNA Probes; D015536:Down-Regulation / Q000187:drug effects*; D015870:Gene Expression; D007700:Kinetics; D009693:Nucleic Acid Hybridization; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000235:genetics* / Q000378:metabolism
chemical_list: D015342:DNA Probes; D012333:RNA, Messenger; D011976:Receptors, Muscarinic; D011813:Quinuclidinyl Benzilate; D002217:Carbachol