title: Fluoxetine modulates hippocampal cell signaling pathways implicated in neuroplasticity in olfactory bulbectomized mice.
abstract: The olfactory bulbectomy (OB) animal model of depression is a well-established model that is capable of detecting antidepressant activity following chronic drug therapy, and the surgery results in behavioral and biochemical changes that are reminiscent of various symptoms of depression. In the present study, we investigated the degree to which 14 days of p.o. administration of the classic antidepressant fluoxetine (10mg/kg) were able to reverse OB-induced changes in behavior (namely, hyperactivity in the open-field test and reduced motivational and self-care behaviors in the splash test) and in the activation of hippocampal cell signaling pathways that are thought to be involved in synaptic plasticity. OB caused significant increases in ERK1 and CREB (Ser(133)) phosphorylation and in the expression of BDNF immunocontent, all of which were prevented by fluoxetine administration. Moreover, fluoxetine administration also caused a significant decrease in ERK2 phosphorylation in mice that had undergone OB. Neither Akt nor GSK-3β phosphorylation was altered in any experimental condition. In conclusion, the present study shows that OB can induce significant behavioral changes that are accompanied by the activation of hippocampal signaling pathways, namely the ERK1/CREB/BDNF pathway, which is involved in the synaptic plasticity. Conversely, fluoxetine prevented these OB-induced behavioral changes and avoided the activation of ERK1/CREB/BDNF in the hippocampus. Taken together, our results extend the data from the existing literature regarding OB-induced behavioral and neurochemical changes, and suggest a possible underlying mechanism that can account for the antidepressant effect of fluoxetine in this model.
authors.affiliation: Department of Biochemistry, Center of Biological Sciences, Universidade Federal de Santa Catarina, Campus Universitário, Trindade 88040-900, Florianópolis, SC, Brazil.
authors.forename: Andiara E
authors.initials: AE
authors.lastname: Freitas
authors.forename: Daniele G
authors.initials: DG
authors.lastname: Machado
authors.forename: Josiane
authors.initials: J
authors.lastname: Budni
authors.forename: Vivian B
authors.initials: VB
authors.lastname: Neis
authors.forename: Grasiela O
authors.initials: GO
authors.lastname: Balen
authors.forename: Mark W
authors.initials: MW
authors.lastname: Lopes
authors.forename: Luiz Felipe
authors.initials: LF
authors.lastname: de Souza
authors.forename: Alcir L
authors.initials: AL
authors.lastname: Dafre
authors.forename: Rodrigo B
authors.initials: RB
authors.lastname: Leal
authors.forename: Ana Lúcia S
authors.initials: AL
authors.lastname: Rodrigues
mesh_terms: D000704:Analysis of Variance; D059445:Anhedonia / Q000187:drug effects; D000818:Animals; D018687:Antidepressive Agents, Second-Generation / Q000494:pharmacology*; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism; D050882:CREB-Binding Protein / Q000378:metabolism; D004195:Disease Models, Animal; D005106:Exploratory Behavior / Q000187:drug effects; D005260:Female; D005473:Fluoxetine / Q000494:pharmacology*; D005518:Food Preferences / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006624:Hippocampus / Q000166:cytology* / Q000187:drug effects; D006948:Hyperkinesis / Q000188:drug therapy / Q000209:etiology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D009473:Neuronal Plasticity / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects*; D000857:Olfaction Disorders / Q000150:complications / Q000209:etiology; D009830:Olfactory Bulb / Q000601:surgery; D051058:Oncogene Protein v-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D018687:Antidepressive Agents, Second-Generation; D019208:Brain-Derived Neurotrophic Factor; D005473:Fluoxetine; D050882:CREB-Binding Protein; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051058:Oncogene Protein v-akt; D038362:Glycogen Synthase Kinase 3