Studies on synapse formation and opiate dependence

Neuroblastoma x glioma in NG108-15 cells possess opiate, alpha-adrenergic, and muscarinic acetylcholine receptors, which mediate an inhibition of adenylate cyclase. Growth of cells for 12--48 hours in the presence of a receptor--activator gradually results in a compensatory increase in adenylate cyclase activity. Withdrawal of the receptor ligand then results in relatively long-lived increases in adenylate cyclase activity and intracellular cAMP levels. Thus cells grown in the presence of morphine, norepinephrine, or acetylcholine seem to become dependent on the compound to maintain normal cAMP levels.