Role of 5-HT7 receptors of the Median Raphe Nucleus of rats submitted to the forced swimming test

• Grant number: 13/20175-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): January 01, 2014
• Effective date (End): September 30, 2014
• Field of knowledge: Humanities - Psychology - Physiological Psychology
• Principal Investigator: Claudia Maria Padovan
• Grantee: Fabiana Maria das Graças Corsi Zuelli
• Host Institution: Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Existing theories regarding the cause of depressive disorders focus on monoamines, specially the role of serotonin (5-HT). Evidences support the hypothesis that serotoninergic neurotransmission is not only involved with the process of adaptation to aversive events, but it is also sensible to different kinds of stressors. The literature provides evidence that the serotonin pathway connecting the median raphe nucleus (MRN) to the dorsal hippocampus is responsible for the adaptation to repetitive stress, disconnecting the aversive associations learned previously. It was also reported that the forced swimming test (FST) is an unavoidable stress capable of modifying the normal serotoninergic function in the MRN. 5-HT7 is the most recent serotonin receptor identified, and it is expressed throughout the central nervous system, including the hippocampus and the MRN. Although recent studies support the idea that 5-HT7 antagonists have antidepressant effects, little is known about the involvement of 5-HT7 receptors within the MRN. Therefore, the aim of this study is to investigate the role of the serotonin receptor type 5-HT7 in the MRN of rats submitted to the FST. Male wistar rats with guide cannulas aimed to the MRN will receive intracerebral injections of SB 258741 and/or LP-44 (antagonist and agonist of 5-HT7 receptor, respectively) immediately before or after a 15 minutes FST exposure (Pre Test condition). Twenty-four hours later, the animals will be submitted to a 5 minutes FST (Test condition), and at this moment data will be recorded for later behavioural analysis. After that, rats will be anaesthetized with Uretane (5ml/kg) for transcardiac perfusion, followed by the histological analysis of the site of injections. ANOVA will be performed for statistical analysis. (AU)