Brain structures analysis related to nociception and emotional behaviour of rats under unpredictable chronic stress associated to unilateral exodontia

• Grant number: 14/26065-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2015
• End date: July 31, 2016
• Field of knowledge: Biological Sciences - Physiology
• Principal Investigator: Elaine Aparecida Del Bel Belluz Guimarães
• Grantee: Gabrielli Caroline Leal-Luiz
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Among muscle skeletal orofacial pains, those caused by temporomandibular dysfunction (TMD) can be highlighted. This disorder presents multifactorial etiology, and has the malocclusion, traumas, inflammatory process and emotional stress as part of the causal factors. One of the most notable and recent area that has been studied in relation to TMDs is its the involvement with emotional disturbances. The aim of this study is to investigate the effect of unpredictable chronic stress associated to unilateral exodontia, and the administration of diazepam or vehicle on the brain and on plasmatic corticosterone concentration. Our hypothesis is that unpredictable chronic stress associated to unilateral exodontia will lead to modification on plasmatic corticosterone concentration and on neuronal activation on specific regions on central nervous system, involved with nociception and emotional behaviors. The influence of pre-treatment of animals with diazepam, a classic anxiolytic also will be evaluated. Sixty four male Wistar rats (200g) will be randomly divided into two groups: Groups Exodontia (GE): rats submitted to left unilateral exodontia (n=32); and Group Without Exodontia (GS): rats without exodontia (n=32). The groups will be divided into subgroups (n=8): I - without stress, treated with vehicle; II - unpredictable chronic stress treated with vehicle; III - without stress and treated with diazepam; IV - unpredictable chronic stress and treated with diazepam. The rats will be submitted to euthanasia on day 24th after the beginning of the experiment, to obtain the brain for c-Fos and/or Fos B analysis, hematoxylin and eosin staining and blood collection blood collection for plasmatic corticosterone concentration analysis.