Participation of serotonergic receptors 1A and 2A of the dorsomedial hypothalamus in different behavioral defense responses

• Grant number: 12/16694-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2012
• End date: May 31, 2014
• Field of knowledge: Humanities - Psychology - Physiological Psychology
• Principal Investigator: Milena de Barros Viana
• Grantee: Letícia Sumiko Kikuchi
• Host Institution: Instituto de Saúde e Sociedade (ISS). Universidade Federal de São Paulo (UNIFESP). Campus Baixada Santista. Santos , SP, Brazil

Abstract

During the last few years, the study of the physiopathology of anxiety has dedicated considerable attention to the involvement of different neurochemical systems in the modulation of defensive responses to aversive stimuli. The role played by serotonin has been highlighted by the clinical efficacy of several serotonergic compounds for the treatment of different anxiety disorders. The purpose of the present study is to investigate the role played by serotonin in a hypothalamic nucleus implicated with defense, the dorsomedial hypothalamus (DMH). It has been demonstrated that the administration of glutamatergic agonists and of GABAergic antagonists intra-DMH evokes flight behavior, similar to what is observed after the electrical stimulation of this same nucleus. Corroborating these observations, a previous study by our research group has shown that the reversible inactivation of the DMH impairs escape responses evoked by a more naturalistic situation: escape from the open arms of the elevated T-maze (ETM). Besides measuring escape responses, the ETM also allows the measurement of a response related to behavioral inhibition (ETM avoidance). These responses have been respectively related, in terms of psychopathology, to panic disorder and generalized anxiety. In the present study, male Wistar rats will be injected intra-DMH with serotonin 1A (8-OH-DPAT and WAY 100635) and 2A (DOI and ketanserin) agonists and antagonists and, ten min later, submitted to the ETM for avoidance and escape measurements. For locomotor activity assessment, all animals will also be tested in an open field after the tests with the ETM. (AU)