title: Involvement of dopamine D1/D2 receptors on harmane-induced amnesia in the step-down passive avoidance test.
abstract: Ingestion of harmane and other alkaloids derived from plant Peganum harmala has been shown to elicit profound behavioural and toxic effects in humans, including hallucinations, excitation, feelings of elation, and euphoria. These alkaloids in the high doses can cause a toxic syndrome characterized by tremors and convulsions. Harmane has also been shown to act on a variety of receptor systems in the mammalian brain, including those for serotonin, dopamine and benzodiazepines. In animals, it has been reported to affect short and long term memory. In the present study, effects of dopamine D1 and D2 receptor antagonists on the harmane (HA)-induced amnesia and exploratory behaviors were examined in mice. One-trial step-down and hole-board paradigms were used for the assessment of memory retention and exploratory behaviors in adult male NMRI mice respectively. Intraperitoneal (i.p.) administration of HA (5 and 10 mg/kg) immediately after training decreased memory consolidation, while had no effect on anxiety-like behavior. Memory retrieval was not altered by 15- or 30 min pre-testing administration of the D1 (SCH23390, 0.025, 0.05 and 0.1 mg/kg) or D2 (sulpiride 12.5, 25 and 50 mg/kg) receptor antagonists, respectively. In contrast, SCH23390 (0.05 and 0.1 mg/kg) or sulpiride (25 and 50 mg/kg) pre-test administration fully reversed HA-induced impairment of memory consolidation. Finally, neither D1 nor D2 receptor blockade affected exploratory behaviors in the hole-board paradigm. Altogether, these findings strongly suggest an involvement of D1 and D2 receptors modulation in the HA-induced impairment of memory consolidation.
authors.affiliation: Department of Biology, Faculty of Basic Sciences, Azad University, Garmsar branch, Semnan, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Nasehi
authors.forename: Morteza
authors.initials: M
authors.lastname: Piri
authors.forename: Maryam
authors.initials: M
authors.lastname: Nouri
authors.forename: Davood
authors.initials: D
authors.lastname: Farzin
authors.forename: Touraj
authors.initials: T
authors.lastname: Nayer-Nouri
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Zarrindast
mesh_terms: D000647:Amnesia / Q000139:chemically induced* / Q000503:physiopathology; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology*; D001552:Benzazepines / Q000494:pharmacology; D065127:Dopamine D2 Receptor Antagonists; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology; D006247:Harmine / Q000031:analogs & derivatives* / Q000633:toxicity; D008297:Male; D051379:Mice; D010865:Pilot Projects; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D017448:Receptors, Dopamine D2 / Q000502:physiology*
chemical_list: D001552:Benzazepines; D065127:Dopamine D2 Receptor Antagonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; C534628:SCH 23390; D006247:Harmine; C005010:harman