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Master's Dissertation
DOI
10.11606/D.58.2014.tde-12052014-141658
Document
Author
Full name
Daniela Mizusaki Iyomasa
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2014
Supervisor
Committee
Panissi, Christie Ramos Andrade Leite (President)
Garavello, Ivania
Gerlach, Raquel Fernanda
Title in Portuguese
Avaliação morfofisiológica do músculo pterigóideo lateral e da sensibilidade nociceptiva orofacial em ratos com hipofunção mastigatória
Keywords in Portuguese
comportamento de dor orofacial
estresse
exodontia
morfofisiologia
músculo
Abstract in Portuguese
Evidências clínicas sugerem que o estresse emocional pode ser um fator de risco para as desordens temporomandibulares (DTM), bem como para outras funções desempenhadas pelo sistema estomatognático. Ainda é controversa a participação da alteração oclusal na etiopatogenia das dores miofasciais. O músculo pterigoideo lateral foi escolhido pela íntima relação com a articulação temporomandibular (ATM). Assim, o objetivo deste projeto foi avaliar a hipótese de que os diferentes tipos de estresse agudo e crônico (repetido e variado) induzem alterações morfofisiológicas no músculo pterigóideo lateral esquerdo em animais submetidos ou não à exodontia unilateral. Em uma segunda etapa, foi avaliada se o procedimento de exodontia unilateral promove alteração da sensibilidade nociceptiva orofacial. Foram utilizados 60 ratos machos Wistar (250 g), divididos aleatoriamente em 2 grandes protocolos: Exodontia (GE): expostos a exodontia unilateral (n = 30); e Sem Exodontia (GSE): sem exodontia unilateral (n = 30). Cada protocolo foi composto por 6 subgrupos (n = 5 ratos cada): Ag: Estresse agudo; Rep: Estresse crônico repetido; Var: Estresse crônico variado; Form: Avaliação nociceptiva orofacial; Sal: Avaliação nociceptiva orofacial (controle formalina); e C: sem estresse (Controle estresses). O GE foi submetido à exodontia unilateral dos molares superiores esquerdo, sob anestesia com associação de xilazina 4% (10mg/kg) e cetamina 10% (80mg/kg), i.p. Em ambos os grupos: GE e GSE, os ratos dos subgrupos Rep e Var foram submetidos aos protocolos de estresse (por 10 dias) a partir do 14º dia após a exodontia; e no 23º, os animais do subgrupo Ag, foram submetidos ao estresse agudo, e dos subgrupos Form e Sal foram submetidos ao protocolo de Formalina orofacial. Com o término dos experimentos, os animais foram submetidos à eutanásia para obtenção dos músculos para análise. Os estresses crônicos, isolados ou associados à exodontia, afetaram a morfologia, a capacidade oxidativa, o estresse oxidativo e a densidade capilar do músculo pterigoideo lateral esquerdo. Estes sinais demonstram a adaptação deste músculo, no período estudado, e sugerem que a persistência destes estímulos podem levar à respostas mais severas como, por exemplo, desencadear a dor miofacial ligada à DTM.
Title in English
Morphophysiological evaluation of lateral pterigoid muscle and orofacial nociceptive sensibility in rats with masticatory hipofunction
Keywords in English
exodontia
morphophysiology
muscle
orofacial pain behavior
stress
Abstract in English
Clinical evidences have suggested that emotional stress could be a risk factor for temporomandibular joint disorder (TMD), as well as other functions performed by stomatognatic system. Remains controversial the participation of occlusal alteration on the miofascial pain etiopathogenesis. The lateral pterygoid muscle was chosen because of the closely relationship with temporomandibular joint (TMJ). Therefore, the aim of this project was evaluate the hypothesis that different types of acute and chronic (repeted and unpredictable) stress induce morphophysiological alteration on the left lateral pterygoid muscle in animals submitted or not to unilateral exodontia. In a second phase, it was evaluated whether the unilateral exodontia procedure promotes orofacial nociceptive sensibility alteration. Sixty male Wistar rats (250 g) were randomly divided into 2 protocols: Exodontia (GE): exposed to unilateral exodontia (n = 30); and Without Exodontia (GSE): without unilateral exodontia (n = 30). Each protocol was composed by 6 subgroups (n = 5): Ag: Acute Stress; Rep: Repeted Chronic Stress; Var: Unpredictable Chronic Stress; Form: Orofacial Nociception Evaluation; Sal: Orofacial Nociception Evaluation (Formalin Control); and C: No Stress (Stress Control). The GE was submitted to unilateral exodontia of superior left molar under anesthesia with the association of xylazine 4% (10 mg/kg) and ketamine 10% (80 mg/kg), i.p. In both groups: GE and GSE, the rats in subgroups Rep and Var were submitted to the stress protocols (during 10 days) from the 14th day after exodontia, and on day 23rd , the animais from subgroup Ag, were submitted to acute stress, and the subgroups Form and Sal were submitted to the Orofacial Formalin protocol. With the end of the experiments, the animals were submitted to euthanasia to obtaining muscle for analysis. The chronic stress, isolated or associated to exodontia, affected the morphology, oxidative capacity, oxidative stress and capillary density of left lateral pterygoid muscle. These signs show the adaptation of this muscle, during the studied period, suggesting that the persistence of these stimuli can lead to a more severe response, such as, myofascial pain trigger linked to the DTM.
 
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Publishing Date
2014-10-08
 
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