Exodontia-induced muscular hypofunction by itself or associated to chronic stress impairs masseter muscle morphology and its mitochondrial function

Author(s)

Lara Pereira, Yamba Carla ^[1] ; Nascimento, Glauce Crivelaro ^[2] ; Iyomasa, Daniela Mizusaki ^[2] ; Restrepo Fernandez, Rodrigo Alberto ^[2] ; Calzzani, Ricardo Alexandre ^[2] ; Andrade Leite-Panissi, Christie Ramos ^{[2, 3]} ; Novaes, Pedro Duarte ^[4] ; Iyomasa, Mamie Mizusaki ^[2]

Affiliation

^[1] CEULP, Ctr Univ Luterano Palmas, Tocantins - Brazil

^[2] Univ Sao Paulo, Dent Sch RibeiraoPreto, Dept Morphol Physiol & Basic Pathol, Ribeirao Preto, SP - Brazil

^[3] Univ Sao Paulo, Sch Philosophy Sci & Literature RibeiraoPreto, Psychobiol Grad Program, Ribeirao Preto, SP - Brazil

^[4] Univ Estadual Campinas, Fac Dent Piracicaba, Campinas, SP - Brazil

• Document type: Journal article
• Source: MICROSCOPY RESEARCH AND TECHNIQUE; v. 82, n. 5, p. 530-537, MAY 2019.
• Web of Science Citations: 0

Abstract

Stress is associated with orofacial pain sensitivity and is qualified as a temporomandibular disorder risk factor. During stressful periods, painful thresholds of masticatory muscles in individuals suffering muscle facial pain are significantly lower than in controls, but the exact physiologic mechanism underlying this relation remains unclear. Our hypothesis is that chronic unpredictable stress and masticatory hypofunction induce morphologic and metabolic masseter muscle changes in rats. For test this hypothesis, adult Wistar rats were submitted to chronic unpredictable stress and/or exodontia of left molars and the left masseter muscle was removed for analysis. The parameters evaluated included ultrastructure, oxidative level, metabolism activity and morphological analysis in this muscle. Our data show by histological analysis, that stress and exodontia promoted a variation on diameters and also angled contours in masseter fibers. The masticatory hypofunction increased oxidative metabolism as well as decreased reactive species of oxygen in masseter muscle. The ultrastructural analysis of muscle fibers showed disruption of the sarcoplasmic reticulum cisterns in certain regions of the fiber in stress group, and the disappearance of the sarcoplasmic reticulum membrane in group with association of stress and exodontia. Our findings clarify mechanisms by which chronic stress and masticatory hypofunction might be involved in the pathophysiology of muscular dysfunctions. Masticatory hypofunction influenced oxidative stress and induced oxidative metabolism on masseter muscle, as well as altered its fiber morphology. Chronic stress presented malefic effect on masseter morphology at micro and ultra structurally. When both stimuli were applied, there were atrophic fibers and a complete mitochondrial derangement. (AU)

• FAPESP's process: 15/03053-3 - Evaluation of medial pterygoid muscle and brain structures related to orofacial nociception and emotional behavior in an animal model of chronic stress and masticatory hypofunction
• Grantee: Glauce Crivelaro Do Nascimento
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 12/22128-6 - Effects of systemic stress associated with malocclusion medial pterygoid muscle and the brain
• Grantee: Mamie Mizusaki Iyomasa
• Support Opportunities: Regular Research Grants