Morphofunctional evaluation of medial pterygoid muscle in rats under systemic stress associated to unilateral exodontia

• Grant number: 14/26057-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): March 01, 2015
• Effective date (End): October 31, 2016
• Field of knowledge: Biological Sciences - Morphology - Anatomy
• Principal Investigator: Mamie Mizusaki Iyomasa
• Grantee: Bruno Lima Malzone
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Orofacial muscle skeletal pains, those caused by temporomandibular dysfunctions (TMD), have been highlighted by the prevalence on odontology clinics and by its multidisciplinary characteristic. This disorder presents multifactorial etiology, wherein malocclusion, traumas, inflammatory process and emotional stress are part of the causal factors. The aim of this study is to investigate the effect of unpredictable chronic stress associated to unilateral exodontia, and the administration of diazepam on medial pterygoid muscle and the plasmatic concentration of corticosterone. Our hypothesis is that unpredictable chronic stress associated to unilateral exodontia lead to alterations on plasmatic corticosterone concentration and on the morphology, as well as on the physiology of the masticatory muscle, the focus of this study. The pre-treatment influence of animals with diazepam, a classic anxiolytic will also be evaluated. Male Wistar rats (200g) will be randomly divided into two groups: Group Exodontia (GE): rats submitted to left unilateral exodontia (n=32); and Group Without Exodontia (GS): rats without exodontia (n=32). These 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 medial pterygoid muscle for the succinate dehydrogenase (SDH) and reactive oxygen species (ROS) analysis as well as, hematoxylin and eosin staining and blood collection for plasmatic corticosterone concentration analysis.