title: Effects of opioid receptor agonists on cAMP second messenger system.
abstract: OBJECTIVE
  To study the mechanism underlying the difference in physical dependence potential of morphine (Mor), methadone (Met), buprenorphine (Bup), etorphine (Eto), and dihydroetorphine (DHE).
  
  
  METHODS
  Adenylate cyclase of NG108-15 cells were used for studying the effects of different opiates on cAMP second messenger system.
  
  
  RESULTS
  Bup, DHE, and Eto were distinct from Mor in naloxone-precipitated rebound response of cAMP in NG108-15 cells chronically treated with these opiates. Naloxone given to NG108-15 cells treated with Mor for 24 h produced marked rebound response of adenylate cyclase. While no such rebound response was detected when the cells were treated with Bup, DHE, and Eto for 24 h. The naloxone-induced rebound response of cAMP in chronic Met-treated NG108-15 cells was also lower than that in chronic Mor-treated NG108-15 cells. Following a prolonged exposure to Bup, DHE, and Eto for 72 h, the naloxone-induced rebound response of cAMP in these cells was still markedly lower than that in Mor-treated cells. The substitution of Mor with Bup, Met, DHE, and Eto inhibited naloxone-induced rebound response of cAMP in chronic Mor-treated NG108-15 cells.
  
  
  CONCLUSIONS
  There were distinct differences among these opiates in regulating cAMP second messenger system, which was related to their physical dependence potential.
authors.affiliation: Institute of Pharmacology and Toxicology, Academy of Military Medical Sciences, Beijing, China. qinby@nic.bmi.ac.cn
authors.forename: J G
authors.initials: JG
authors.lastname: Liu
authors.forename: Z H
authors.initials: ZH
authors.lastname: Gong
authors.forename: B Y
authors.initials: BY
authors.lastname: Qin
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000701:Analgesics, Opioid / Q000494:pharmacology; D002047:Buprenorphine / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D005048:Etorphine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005910:Glioma / Q000473:pathology; D006801:Humans; D006822:Hybrid Cells; D008691:Methadone / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology*; D009447:Neuroblastoma / Q000473:pathology; D009293:Opioid-Related Disorders / Q000378:metabolism; D011957:Receptors, Opioid / Q000819:agonists*; D017465:Receptors, Opioid, delta / Q000819:agonists*; D014407:Tumor Cells, Cultured
chemical_list: D000701:Analgesics, Opioid; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D002047:Buprenorphine; D005048:Etorphine; D009020:Morphine; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; C034765:18,19-dihydroetorphine; D008691:Methadone