title: Phosphorylation of cyclic AMP response element-binding protein and induction of c-fos gene expression on withdrawal from chronic treatment with carbachol in NG108-15 cells.
abstract: Alterations in adenylyl cyclase activity in cultured cells after prolonged exposure to drugs such as morphine have been extensively studied as models for drug tolerance and withdrawal. NG108-15 cells develop increased intracellular cAMP concentrations after abrupt withdrawal from chronic treatment with the muscarinic cholinergic agonist carbachol. To determine whether this withdrawal-induced increase in cAMP modifies gene expression, we studied phosphorylation of the cAMP response element-binding protein (CREB) and expression of the c-fos gene, known to contain a cAMP response element, in NG108-15 cells after abrupt withdrawal from chronic treatment with carbachol. Prostaglandin E1, which activates adenylyl cyclase, caused concentration-dependent increases in the phosphorylation of CREB and in the abundance of c-fos mRNA. These changes occurred with small increments in cAMP accumulation. In cells treated with carbachol for 48 hr, induction of withdrawal with the muscarinic antagonist atropine led to a small increase in intracellular cAMP concentration but an 11.6-fold increase in the phosphorylation of CREB and a 3.4-fold increase in accumulation of c-fos mRNA. The adenylyl cyclase inhibitor 2',5'-dideoxyadenosine, which attenuated the chronic carbachol-induced increase in cAMP concentration, prevented the increased phosphorylation of CREB and the enhanced accumulation of c-fos mRNA during atropine-induced withdrawal. These results indicate that expression of the c-fos gene is induced by the small increments in cAMP concentration that can occur in cells on withdrawal from chronic treatment with drugs such as muscarinic agonists.
mesh_terms: D000527:Alprostadil / Q000494:pharmacology; D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D016762:Genes, fos; D005910:Glioma; D006822:Hybrid Cells; D051379:Mice; D018721:Muscarinic Agonists / Q000494:pharmacology*; D009447:Neuroblastoma; D010766:Phosphorylation; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D013375:Substance Withdrawal Syndrome / Q000235:genetics* / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D018721:Muscarinic Agonists; D012333:RNA, Messenger; D002217:Carbachol; D000242:Cyclic AMP; D000527:Alprostadil