title: Loss of opiate receptor activity in neuroblastoma X glioma NG108-15 hybrid cells after chronic opiate treatment. A multiple-step process.
abstract: Treatment of NG108-15 cells with 1 nM or 10 nM etorphine for 24 hr produced an identical magnitude of compensatory increase in prostaglandin E1-stimulated adenylate cyclase activity. Activity of etorphine was retained, albeit reduced, in NG108-15 cells treated with 1 nM etorphine but not in cells treated with 10 nM etorphine. Exposure to 100 microM morphine for 72 hr produced a complete loss of morphine and levorphanol but not Leu5-enkephalin activity in NG108-15 hybrid cells. Apparently, the loss of opiate activity involves a multiple-step process. Short-term incubation with 10 nM etorphine (less than 3 hr) produced loss of opiate activity with minimal alteration in [3H]diprenorphine specific binding. Long-term exposure to 10 nM etorphine (greater than or equal to 24 hr) produced down-regulation of the receptor. A mechanism similar to that of beta-adrenergic receptor desensitization may be involved in opiate receptor desensitization in NG108-15 cells.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D004174:Diprenorphine / Q000494:pharmacology; D005910:Glioma / Q000378:metabolism*; D006801:Humans; D006822:Hybrid Cells / Q000378:metabolism*; D007700:Kinetics; D009020:Morphine / Q000494:pharmacology; D009294:Narcotics / Q000494:pharmacology*; D009374:Neoplasms, Experimental / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism*; D011957:Receptors, Opioid / Q000187:drug effects*
chemical_list: D000319:Adrenergic beta-Antagonists; D009294:Narcotics; D011957:Receptors, Opioid; D004174:Diprenorphine; D009020:Morphine; D000262:Adenylyl Cyclases