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

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...

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Published in:Arquivos de neuro-psiquiatria Vol. 70; no. 11; pp. 874 - 879
Main Authors: Sadeghian, Reihaneh, Fereidoni, Masoud, Soukhtanloo, Mohammad, Azizi-Malekabadi, Hamid, Hosseini, Mahmoud
Format: Journal Article
Language:English
Published: Brazil Academia Brasileira de Neurologia - ABNEURO 01.11.2012
Thieme Revinter Publicações
Subjects:
Analysis of Variance
Animals
Contraceptive Agents - administration & dosage
Dose-Response Relationship, Drug
estradiol
Estradiol - administration & dosage
Estradiol - analogs & derivatives
Female
hipocampo
Hippocampus - drug effects
Hippocampus - metabolism
Humans
Learning Disorders - etiology
Learning Disorders - metabolism
Maze Learning - drug effects
Memory - drug effects
Memory Disorders - etiology
Memory Disorders - metabolism
NEUROSCIENCES
Nitric Oxide - biosynthesis
Nitric Oxide - metabolism
Ovariectomy
PSYCHIATRY
Random Allocation
rato
Rats
Rats, Wistar
óxido nítrico
óxido nítrico
nitric oxide
hipocampo
rat
hippocampus
estradiol
rato
ISSN:0004-282X, 1678-4227, 0004-282X, 1678-4227
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Summary: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. Os efeitos de uma alta dose de estradiol na memória e nos metabólitos do óxido nítrico de tecidos hipocampais foram estudados. Os Grupos Sham-Est e OVX-Est foram tratados com 4 mg/kg de valerato de estradiol por 12 semanas. O tempo de latência e o comprimento do caminho foram significativamente maiores nos Grupos Sham-Est e OVX-Est em relação aos Grupos Sham e OVX, respectivamente (p<0,001). Os animais dos Grupos Sham-Est e OVX-Est passaram menos tempo na meta do quadrante (Q1) do que aqueles dos Grupos Sham e OVX durante o teste inicial (p<0,05 e <0,001, respectivamente). Níveis significativamente menores de metabólitos do óxido nítrico foram observados nos hipocampos dos Grupos Sham-Est e OVX-Est em relação aos Grupos Sham e OVX (p<0,001). Esses resultados sugerem que os níveis diminuídos de óxido nítrico no hipocampo podem ter um papel nos déficits de aprendizado e de memória, que são observados após tratamento com alta dose de estradiol, embora os mecanismos específicos envolvidos nestes achados ainda precisam ser elucidados.
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ISSN:0004-282X
1678-4227
0004-282X
1678-4227
DOI:10.1590/S0004-282X2012001100010