title: Chronic morphine treatment inhibits oxytocin synthesis in rats.
abstract: The changes of oxytocin content and mRNA expression in some nuclei were investigated in morphine-dependent rats using radioimmunoassay (RIA) and in situ hybridization (ISH). After chronic administration of morphine, the oxytocin content in supraoptic nucleus (SON) and nucleus accumbens (NAc) decreased, and increased in the ventral tegment area (VTA) and locus coeruleus (LC), but did not change in other nuclei including the paraventricular nucleus (PVN), lateral septum (SEPTUM), raphe magnus nucleus (NRM) and periaquaductal gray (PAG). In morphine-L dependent rats, naloxone increased the levels of oxytocin in SON and PVN, but decreased that in LC. ISH first showed that chronic morphine treatment inhibited the oxytocin synthesis in SON but not in PVN. The present study demonstrates that chronic morphine treatment alters the brain oxytocin system, suggesting that oxytocin might contribute to the behavioral and neuroendocrine responses to morphine.
authors.affiliation: Department of Neurobiology, Second Military Medical University, Shanghai, PR China.
authors.forename: Z D
authors.initials: ZD
authors.lastname: You
authors.forename: J H
authors.initials: JH
authors.lastname: Li
authors.forename: C Y
authors.initials: CY
authors.lastname: Song
authors.forename: C H
authors.initials: CH
authors.lastname: Wang
authors.forename: C L
authors.initials: CL
authors.lastname: Lu
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D004334:Drug Administration Schedule; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009021:Morphine Dependence / Q000473:pathology / Q000503:physiopathology; D009270:Naloxone / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D010121:Oxytocin / Q000096:biosynthesis* / Q000187:drug effects* / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013375:Substance Withdrawal Syndrome / Q000473:pathology / Q000503:physiopathology; D013495:Supraoptic Nucleus / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D009270:Naloxone; D010121:Oxytocin; D009020:Morphine