title: Withdrawal from repeated administration of morphine alters histamine-induced anxiogenic effects produced by intra-ventral hippocampal microinjection.
abstract: In the present study, the influence of withdrawal from repeated administration of morphine on intra-ventral hippocampal microinjection of histamine-induced anxiety-like behavior was investigated in male Wistar rats. Three days subcutaneous administration of morphine (5-10 mg/kg) followed by five days free of the drug decreased the percentage open arm time and the percentage open arm entries. Intra-ventral hippocampal administration of histamine (2.5-7.5 microg/rat) decreased percentage open arm time and percentage open arm entries. Intra-ventral hippocampal histamine-induced anxiogenic effect was reversed in animals that had previously received the three days morphine (7.5 mg/kg) followed by five days free of the drug. Intra-ventral hippocampal administration of pyrilamine (5-20 microg/rat) or ranitidine (10-40 microg/rat) decreased percentage open arm time and percentage open arm entries. Pyrilamine- or ranitidine-induced anxiogenic effect was not changed in animals that had previously received the three days morphine (7.5 mg/kg) followed by five days free of the drug. Intra-ventral hippocampal injections of clobenpropit increased percentage open arm time. The percentage open arm time and percentage open arm entries were decreased in the morphine-treated animals compared with non-morphine-treated controls. Percentage open arm entries and locomotor activity was reduced with some doses of clobenpropit. It can be concluded that the histamine system is involved in anxiety-like behavior, and repeated injections of morphine followed by five days free of the drugs interact with histamine receptor mechanism.
authors.affiliation: Department of Pharmacology, School of Medicine and Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran. zarinmr@ams.ac.ir
authors.forename: Mohammad-Reza
authors.initials: MR
authors.lastname: Zarrindast
authors.forename: Parvin
authors.initials: P
authors.lastname: Khodarahmi
authors.forename: Ameneh
authors.initials: A
authors.lastname: Rezayof
authors.forename: Shahrbano
authors.initials: S
authors.lastname: Oryan
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000139:chemically induced*; D001522:Behavior, Animal / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects*; D006632:Histamine / Q000008:administration & dosage*; D006633:Histamine Antagonists / Q000008:administration & dosage; D007093:Imidazoles / Q000008:administration & dosage; D008297:Male; D008845:Microinjections; D009020:Morphine / Q000009:adverse effects*; D009043:Motor Activity / Q000187:drug effects; D011738:Pyrilamine / Q000008:administration & dosage; D011899:Ranitidine / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D013375:Substance Withdrawal Syndrome; D013890:Thiourea / Q000008:administration & dosage / Q000031:analogs & derivatives
chemical_list: D006633:Histamine Antagonists; D007093:Imidazoles; D009020:Morphine; D006632:Histamine; D011899:Ranitidine; D013890:Thiourea; D011738:Pyrilamine; C086108:clobenpropit