title: Decreased nitric oxide levels in the hippocampus may play a role in learning and memory deficits in ovariectomized rats treated by a high dose of estradiol.
abstract: The effects of a high estradiol dose on memory and on nitric oxide metabolites in hippocampal tissues were investigated. Sham-Est and OVX-Est Groups were treated with 4 mg/kg of estradiol valerate for 12 weeks. Time latency and path length were significantly higher in the Sham-Est and OVX-Est Groups than in the Sham and OVX Groups, respectively (p<0.001). The animals in the Sham-Est and OVX-Est Groups spent lower time in the target quadrant (Q1) than those of the Sham and OVX Groups during the probe trial test (p<0.05 and <0.001, respectively). Significantly lower nitric oxide metabolite levels in the hippocampi of the Sham-Est and OVX-Est Groups were observed than in the Sham and OVX ones (p<0.001). These results suggest that decreased nitric oxide levels in the hippocampus may play a role in the learning and memory deficits observed after treatment with a high dose of estradiol, although the precise underlying mechanisms remain to be elucidated.
authors.affiliation: Department of Biology, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran.
authors.forename: Reihaneh
authors.initials: R
authors.lastname: Sadeghian
authors.forename: Masoud
authors.initials: M
authors.lastname: Fereidoni
authors.forename: Mohammad
authors.initials: M
authors.lastname: Soukhtanloo
authors.forename: Hamid
authors.initials: H
authors.lastname: Azizi-Malekabadi
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Hosseini
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D003270:Contraceptive Agents / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D005260:Female; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007859:Learning Disabilities / Q000209:etiology* / Q000378:metabolism; D018782:Maze Learning / Q000187:drug effects; D008568:Memory / Q000187:drug effects; D008569:Memory Disorders / Q000209:etiology* / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis / Q000378:metabolism*; D010052:Ovariectomy; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar
chemical_list: D003270:Contraceptive Agents; D009569:Nitric Oxide; D004958:Estradiol