Unpredictable chronic mild stress exerts anxiogenic-like effects and activates neurons in the dorsal and caudal region and in the lateral wings of the dorsal raphe nucleus

Unpredictable chronic mild stress exerts anxiogenic-like effects and activates neurons in the dorsal and caudal region and in the lateral wings of the dorsal raphe nucleus

Author Lopes, Danielle Abreu Autor UNIFESP Google Scholar
Lemes, Jessica A. Autor UNIFESP Google Scholar
Melo-Thomas, Liana Google Scholar
Schor, Herbert Autor UNIFESP Google Scholar
de Andrade, Jose S. Autor UNIFESP Google Scholar
Machado, Carla M. Google Scholar
Horta-Junior, Jose A. C. Google Scholar
Cespedes, Isabel Cristina Autor UNIFESP Google Scholar
Viana, Milena de Barros Autor UNIFESP Google Scholar
Abstract In previous studies, we verified that exposure to unpredictable chronic mild stress (UCMS) facilitates avoidance responses in the elevated T-maze (ETM) and increased Fos-immunoreactivity in different brain structures involved in the regulation of anxiety, including the dorsal raphe (DR). Since, it has been shown that the DR is composed of distinct subpopulations of serotonergic and non-serotonergic neurons, the present study investigated the pattern of activation of these different subnuclei of the region in response to this stress protocol. Male Wistar rats were either unstressed or exposed to the UCMS procedure for two weeks and, subsequently, analyzed for Fos-immunoreactivity (Fos-ir) in serotonergic cells of the DR. To verify if the anxiogenic effects observed in the ETM could be generalized to other anxiety models, a group of animals was also tested in the light/dark transition test after UCMS exposure. Results showed that the UCMS procedure decreased the number of transitions and increased the number of stretched attend postures in the model, an anxiogenic effect. UCMS exposure also increased Fos-ir and the number of double-labeled neurons in the mid-rostral subdivision of the dorsal part of the DR and in the mid-caudal region of the lateral wings. In the caudal region of the DR there was a significant increase in the number of Fos-ir. No significant effects were found in the other DR subnuclei. These results corroborate the idea that neurons of specific subnuclei of the DR regulate anxiety responses and are differently activated by chronic stress exposure. (C) 2015 Elsevier B.V. All rights reserved.
Keywords Unpredictable Chronic Mild Stress
Anxiety
Dorsal Raphe
Fos Immunoreactivity
SerotoninElevated T-Maze
Serotonergic Systems
Plus-Maze
Dorsomedial Hypothalamus
Defensive Behaviors
Affective-Disorders
Experimental-Model
Risk-Assessment
Open-Field
In-Vitro
Language English
Sponsor Sao Paulo State Research Foundation (FAPESP, BRAZIL)
Coordination for the Improvement of Higher Education Personnel (CAPES, Brazil)
National Council for Scientific and Technological Development (CNPq, Brazil)
Grant number FAPESP: 2013/17389-8
Date 2016
Published in Behavioural Brain Research. Amsterdam, v. 297, p. 180-186, 2016.
ISSN 0166-4328 (Sherpa/Romeo, impact factor)
Publisher Biomed Central Ltd
Extent 180-186
Origin https://doi.org/10.1016/j.bbr.2015.10.006
Access rights Closed access
Type Article
Web of Science ID WOS:000367107900023
URI http://repositorio.unifesp.br/handle/11600/49186

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