title: Chronic administration of Org2766 and morphine counteracts isolation-induced increase in social interest: implication of endogenous opioid systems.
abstract: In complex behaviors, like social behavior, the MSH/ACTH (4-9) analog Org2766 is found to counteract changes in social interest caused by preceding housing or test conditions. Previous studies have indicated an involvement of endogenous opioid systems in these outcomes. In the present study we have counteracted isolation-induced enhanced social interest by chronic treatment (7 x every 48 h) with Org2766 or with the opiate morphine. These effects were blocked by previous administration of naloxone. However, in group-housed animals, both Org2766 and morphine treatment did not result in changes in social activity as compared to saline-treated group-housed controls. Chronic administration of naloxone in group-housed rats resulted in an increase in social interest. These results are discussed in relation to possible function of Org2766 and morphine as a substitute for the release of endogenous opioids caused by social contact.
authors.affiliation: Rudolf Magnus Institute for Neurosciences, University of Utrecht, The Netherlands.
authors.forename: T
authors.initials: T
authors.lastname: Hol
authors.forename: S
authors.initials: S
authors.lastname: Ruven
authors.forename: J M
authors.initials: JM
authors.lastname: Van Ree
authors.forename: B M
authors.initials: BM
authors.lastname: Spruijt
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D000927:Anticonvulsants / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects* / Q000502:physiology; D015331:Cohort Studies; D006799:Housing, Animal; D007279:Injections, Subcutaneous; D008297:Male; D009020:Morphine / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010446:Peptide Fragments / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012919:Social Behavior; D012934:Social Isolation; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D000927:Anticonvulsants; D009292:Narcotic Antagonists; D010446:Peptide Fragments; D009270:Naloxone; C013765:Org 2766; D009020:Morphine; D000324:Adrenocorticotropic Hormone