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Effects of systemic stress associated with malocclusion medial pterygoid muscle and the brain


The temporomandibular (TMD) has a high prevalence in our society, being characterized by a severe condition of pain of the muscles of mastication and/or the temporomandibular joint. Despite the multiple factors contributing to the DTM initiators, including emotional stress, there is still controversy as to its etiology is little understood and its pathophysiology. Using the mouse as experimental animal model, this study aims to investigate the effect of varied chronic stress associated with tooth extraction, and whether or not administration of diazepam on the medial pterygoid muscle, brain and on plasma concentration of cortisol. Our hypothesis is that chronic stress varied associated with malocclusion will induce plastic modifications, causing changes in the morphology of the fibers, capillary density, contractile ability of the fibres, oxidative metabolism in muscle, inflammatory process in plasma concentration of cortisol and the neuronal activation of specific regions of the central nervous system. Pretreatment of the animals with diazepam, a classic anxiolytic, will neutralize or reduce the cellular and neural responses. Thus, the objective of this work will be to assess the medial pterygoid muscle, bilaterally, the brain and the blood of these animals. Wistar male rats 64 shall be used, young adults, weighing on average 200 g, randomly divided into two large groups: groups Malocclusion (GM): rats exposed to the left side tooth extraction (n32); and the group without Malocclusion (GS): mice without dental extraction (n32). In each group there will be the following subgroups (n8) in each: I - no stress; II: chronic stress varied; III: without stress and treated with diazepam; IV: chronic stress varied and treated with diazepam. The animals of malocclusion (GM) will be subjected to unilateral upper left molar extraction under intraperitoneal anesthesia, with 4 (10mgkg) Xylazine and Ketamine 10 (80mgkg), on day zero. In both groups: GM and GS, the rats of the subgroups II and IV shall be subject to protocols other than stress, from the fourteenth day after the tooth extraction. The protocols will be different each day for five consecutive days, which are repeated from the 6th day for five days. The mice will be undergoing euthanasia on the 24th day after the beginning of the experiment, to obtain bilateral medial pterygoid muscle, and subsequent morphological analysis, Histochemical, and ultrastructural immuno labeling; obtaining the brain for analysis of c-Fos and or Fos-B and; collection of blood for analysis of plasma concentration of cortisol. (AU)

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Scientific publications (4)
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
RESTREPO FERNANDEZ, RODRIGO ALBERTO; LARA PEREIRA, YAMBA CARLA; IYOMASA, DANIELA MIZUSAKI; CALZZANI, RICARDO ALEXANDRE; ANDRADE LEITE-PANISSI, CHRISTIE RAMOS; IYOMASA, MAMIE MIZUSAKI; NASCIMENTO, GLAUCE CRIVELARO. Metabolic and vascular pattern in medial pterygoid muscle is altered by chronic stress in an animal model of hypodontia. Physiology & Behavior, v. 185, p. 70-78, . (12/22128-6, 15/03053-3)
NASCIMENTO, GLAUCE C.; MALZONE, BRUNO L.; IYOMASA, DANIELA M.; PEREIRA, YAMBA C. L.; ISSA, JOAO PAULO M.; LEITE-PANISSI, CHRISTIE R. A.; WATANABE, II-SEI; IYOMASA, MAMIE M.; FUENTES, RAMON; DEL BEL, ELAINE; et al. Beneficial effects of benzodiazepine on masticatory muscle dysfunction induced by chronic stress and occlusal instability in an experimental animal study. SCIENTIFIC REPORTS, v. 10, n. 1, . (12/22128-6, 15/03053-3)
LARA PEREIRA, YAMBA CARLA; NASCIMENTO, GLAUCE CRIVELARO; IYOMASA, DANIELA MIZUSAKI; RESTREPO FERNANDEZ, RODRIGO ALBERTO; CALZZANI, RICARDO ALEXANDRE; ANDRADE LEITE-PANISSI, CHRISTIE RAMOS; NOVAES, PEDRO DUARTE; IYOMASA, MAMIE MIZUSAKI. Exodontia-induced muscular hypofunction by itself or associated to chronic stress impairs masseter muscle morphology and its mitochondrial function. MICROSCOPY RESEARCH AND TECHNIQUE, v. 82, n. 5, p. 530-537, . (15/03053-3, 12/22128-6)
LOYOLA, BRUNO MELO; NASCIMENTO, GLAUCE CRIVELARO; RESTREPO FERNANDEZ, RODRIGO ALBERTO; IYOMASA, DANIELA MIZUSAKI; LARA PEREIRA, YAMBA CARLA; ANDRADE LEITE-PANISSI, CHRISTIE RAMOS; MARDEGAN ISSA, JOAO PAULO; IYOMASA, MAMIE MIZUSAKI. Chronic stress effects in contralateral medial pterygoid muscle of rats with occlusion alteration. Physiology & Behavior, v. 164, n. A, p. 369-375, . (12/22128-6)

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