scholarly journals Functional Changes of Temporomandibular Joint Mechanoreceptors Induced by Reduced Masseter Muscle Activity in Growing Rats

2009 ◽  
Vol 79 (5) ◽  
pp. 978-983 ◽  
Author(s):  
Takayoshi Ishida ◽  
Tadachika Yabushita ◽  
Kunimichi Soma
Keyword(s):  
Temporomandibular Joint ◽  
Muscle Activity ◽  
Masseter Muscle ◽  
Growth Period ◽  
Control Group ◽  
Functional Changes ◽  
Male Wistar Rats ◽  
Masseter Muscles ◽  
Experimental Group ◽  
Indirect Stimulation

Abstract Objective: To determine the influence of masseter muscle activity during growth on the functional characteristics of temporomandibular joint (TMJ) mechanoreceptors. Materials and Methods: Sixty-six 3-week-old male Wistar rats were divided into an experimental group, in which the masseter muscles were bilaterally resected at 3 weeks of age, and a control group. Single-unit activities of the TMJ mechanoreceptors were evoked by indirect stimulation of passive jaw movement. Electrophysiologic recordings of TMJ units were made at 5, 7, and 9 weeks of age. Results: During this period, the firing threshold of the TMJ units was significantly lower and the maximum instantaneous frequency of the TMJ units was significantly higher in the experimental group than in the control group. Conclusion: Reduced masseter activity during the growth period alters the response properties of TMJ mechanoreceptors.

scholarly journals Masseter Muscle Activity in Orthodontically Treated Patients with a History of Temporomandibular Joint Disorder: An Electromyographic Study

2021 ◽  
Vol 16 (2) ◽  
pp. 191-198
Author(s):  
Nisallina Apridini ◽  
Nia Ayu Ismaniati Noerhadi ◽  
Erwin Siregar
Keyword(s):  
Temporomandibular Joint ◽  
Muscle Activity ◽  
Masseter Muscle ◽  
Maximum Voluntary Contraction ◽  
Control Group ◽  
Temporomandibular Joint Disorder ◽  
Joint Disorder ◽  
History Of ◽  
Masseter Muscles ◽  
Semg Activity

The present study aimed to evaluate the surface electromyography (sEMG) activity of the masseter muscles in patients with a history of temporomandibular joint disorder (TMJD) who received orthodontic treatment. In total, 22 participants aged 18–35 years old were included in this study. They were divided into the control group (patients without a history of TMJD [n = 11]) and the test group (those with a history of TMJD [n = 11]). Each participant underwent sEMG of the right and left masseter muscles at 5-s maximum voluntary contraction (MVC). Results showed that the TMJD group had a lower sEMG activity of masseter muscles at MVC than the non-TMJD group. However, the differences were not statistically significant (p > 0.05, t-test). The Spearman’s correlation coefficient test revealed a weak negative correlation between muscle activity on sEMG and history of TMJD (p > 0.05). In conclusion, orthodontically treated patients in TMJD group have reduced masseter muscle activity during MVC, compare to the non-TMJD group.

scholarly journals Masseter Muscular Weakness Affects Temporomandibular Synovitis Induced by Jaw Opening in Growing Rats

2008 ◽  
Vol 78 (5) ◽  
pp. 819-825 ◽  
Author(s):  
Miho Ozaki ◽  
Sawa Kaneko ◽  
Kunimichi Soma
Keyword(s):  
Growth Period ◽  
Control Group ◽  
Tissue Samples ◽  
Synovial Hyperplasia ◽  
Jaw Opening ◽  
Male Wistar Rats ◽  
Cox 2 ◽  
Oxide Synthase ◽  
Inflammatory Changes ◽  
Masseter Muscles

Abstract Objective: To evaluate the influence of impaired masseter function during growth on the development of temporomandibular synovitis. Materials and Methods: Sixteen 3-week-old male Wistar rats were classified into four groups. The first group served as control; and in the second group, jaw opening was forced for 3 hours when the rats were 9 weeks old. In the third and fourth groups, the masseter muscles were bilaterally resected at 3 weeks of age, and the rats in the fourth group were additionally forced to open their jaw at 9 weeks of age. All rats were sacrificed at 9 weeks. Temporomandibular joint (TMJ) tissue samples were processed for histology, and evaluated for cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expressions by immunohistochemistry to examine the inflammatory changes in the synovial membrane. Results: The control group showed noninflammatory changes. In the jaw-opening group, vascular dilation and weak COX-2 immunoreactivity were induced by jaw opening in the synovium. In the masseter-resection group, the masseter-resected rats exhibited moderate synovial changes while in the resection with opening group, the masseter-resected rats revealed more significant inflammatory changes including synovial hyperplasia, dilated vasculature, fibrin deposits, and intense immunoreactivity for COX-2 and iNOS, all caused by jaw opening. Conclusions: These results suggest that masseter activity in the growth period is an important factor in the induction of temporomandibular synovitis.

Explosion-Induced Neurotrauma (Pathophysiological and Patomorphological Features)

2021 ◽  
Vol 6 (5) ◽  
pp. 83-88
Author(s):  
Yu. V. Kozlova ◽  
◽  
V. V. Koldunov ◽  
O. A. Aleksjejenko ◽  
K. S. Kozlova ◽  
...  
Keyword(s):  
White Male ◽  
Biomedical Ethics ◽  
Control Group ◽  
Standard Diet ◽  
Barnes Maze ◽  
Functional Changes ◽  
Latent Time ◽  
Male Wistar Rats ◽  
Post Traumatic ◽  
Experimental Group

The article presents the results of pathophysiological and pathomorphological features which were studied in experimental blust-induced neurotrauma in rats. The relevance of this study is associated with the frequent blust neurotrauma resulting from the use of explosives in military conflicts. At the same time, neurotrauma is more common, which is clinically manifested by cognitive impairment, even with mild and moderate severity. This, in turn, leads to complications and disability for young people. The purpose of the work was to study the consequences of the air-shock wave influence on the functional and morphological states of the central nervous system. Materials and methods. The studies were carried out on 36 white male Wistar rats 5-7 months old, weighing 180-220 g. The rats were divided into two groups: I – experimental group (n=18), the animals of which were anesthetized with halothane, fixed and explosion-induced neurotraum was simulated by generating a baroacoustic wave with an excess pressure of 26.4 ± 3.6 kPa. II group was a control group (n=18). Functional changes were investigated in the Barnes maze. For pathomorphological examination, brain sections were stained with hematoxylin and eosin. The animals were kept in standard conditions and in the standard diet of the vivarium, all studies were conducted in accordance with modern international requirements and norms of humane treatment of animals (Council of Europe Convention dated 18.03.1986 (Strasbourg); Helsinki Declaration 1975, revised and supplemented in 2000, Law of Ukraine dated 21.02.2006 No. 3447-IV), which is evidenced by an extract from the protocols of the meeting of the commission on biomedical ethics. Results and discussion. Analysis of the results of memory studies in the Barnes maze showed a significant (Р <0.05) increase in the latent time of entering the shelter in rats of the experimental group in the acute and early post-traumatic period, which indicates memory impairment. General characteristics of the rats behavior in the experimental group showed an increase in anxiety and disorientation. The increase in research on "fake shelters" and the chaotic movement around the facility was evidenced. Analysis of frontal histological sections of the rat brain in the dynamics of the explosion-induced neurotrauma development showed the presence of characteristic signs in the form of diffuse microhemorrhages in the hippocampus zone in the acute period of injury, diffuse areas of perivascular and pericellular edema in the early post-traumatic period and paretic dilated capillaries in the structure of the cerebral region on 2nd-3rd week of the post-traumatic period. Conclusion. Thus, quantitative (increased latent time) and qualitative (increased anxiety) signs of impaired orientational-spatial memory and the development of specific pathomorphological signs of explosive brain damage in rats of the experimental group were established

scholarly journals The use of Portland cement in the repair of mandibular fractures in rats

2011 ◽  
Vol 26 (6) ◽  
pp. 426-432
Author(s):  
Reginaldo Inojosa Carneiro Campello ◽  
Belmiro Cavalcanti do Egito Vasconcelos ◽  
Gerhilde Callou Sampaio ◽  
Antonio Rolim ◽  
Gabriela Granja Porto
Keyword(s):  
Portland Cement ◽  
Bone Healing ◽  
Soft Tissues ◽  
Lethal Dose ◽  
Mandibular Fracture ◽  
Point Of View ◽  
Control Group ◽  
Mandibular Fractures ◽  
Male Wistar Rats ◽  
Experimental Group

PURPOSE: To evaluate the bone healing of mandibular fractures following the use of Portland cement. METHODS: Thirty-two male Wistar rats were divided into control and experimental groups. In the control group the rats were submitted to a mandibular fracture, which was reduced, and the soft tissues were sutured. In the experimental group the rats had the mandibular fracture reduced and maintained with the Portland cement. The animals were euthanized 7 and 21 days after surgery by injecting a lethal dose of anesthetic. The following variables were studied: weight of the animals, radiographic images, histopathological features and time of surgery. RESULTS: A weight loss was observed in the specimens of both groups at the different times of evaluation, a greater difference in weight before and after surgery being found in the experimental group, which was statistically significant (p <0.05, p = 0.041). From the histological point of view, with a margin of error (5.0%) the only two significant differences (p <0.05) recorded in the variables were "Material deployed" and "Bone resorption" during the evaluations at 7 and 21 days, respectively. CONCLUSION: The Portland cement served to promote bone healing.

scholarly journals A Subpressor Dose of Angiotensin II Elevates Blood Pressure in a Normotensive Rat Model by Oxidative Stress

2015 ◽  
pp. 153-159 ◽  
Author(s):  
M. M. GOVENDER ◽  
A. NADAR
Keyword(s):  
Oxidative Stress ◽  
Blood Pressure ◽  
Angiotensin Ii ◽  
Mrna Expression ◽  
Rat Model ◽  
Wistar Rat ◽  
Control Group ◽  
Sod Activity ◽  
Male Wistar Rats ◽  
Experimental Group

Oxidative stress is an imbalance between free radicals and antioxidants, and is an important etiological factor in the development of hypertension. Recent experimental evidence suggests that subpressor doses of angiotensin II elevate oxidative stress and blood pressure. We aimed to investigate the oxidative stress related mechanism by which a subpressor dose of angiotensin II induces hypertension in a normotensive rat model. Normotensive male Wistar rats were infused with a subpressor dose of angiotensin II for 28 days. The control group was sham operated and infused with saline only. Plasma angiotensin II and H2O2 levels, whole-blood glutathione peroxidase, and AT-1a, Cu/Zn SOD, and p22phox mRNA expression in the aorta was assessed. Systolic and diastolic blood pressures were elevated in the experimental group. There was no change in angiotensin II levels, but a significant increase in AT-1a mRNA expression was found in the experimental group. mRNA expression of p22phox was increased significantly and Cu/Zn SOD decreased significantly in the experimental group. There was no significant change to the H2O2 and GPx levels. Angiotensin II manipulates the free radical-antioxidant balance in the vasculature by selectively increasing O2− production and decreasing SOD activity and causes an oxidative stress induced elevation in blood pressure in the Wistar rat.

scholarly journals Increased vertical dimension effects on masseter muscle fiber phenotype during maturation

2012 ◽  
Vol 83 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Charles Widmer ◽  
Vo Danh Nguyen ◽  
Harmeet Chiang ◽  
Joyce Morris-Wiman
Keyword(s):  
Muscle Fiber ◽  
Masseter Muscle ◽  
Fiber Diameter ◽  
Vertical Dimension ◽  
Control Group ◽  
Maxillary Molars ◽  
Fiber Size ◽  
And Control ◽  
Masseter Muscles ◽  
Anterior Posterior

Abstract Objective: To determine changes in mouse myosin heavy chain (MyHC) protein expression that may occur with a clinically relevant vertical dimension of occlusion (VDO) increase. Materials and Methods: Six CD-1 male mice (age: 6 weeks) underwent a 10% bite opening to replicate the clinical condition using composite on the maxillary molars and were compared to six age-matched controls. Mice were sacrificed at day 7 and 14 after bite opening. A representative masseter transverse cryosection from each animal was examined in selected sampling regions (anterior, posterior, posterior-deep, and posterior-intermediate) to assay fiber phenotype proportions and fiber size. Results: In control masseter muscles, the proportion of muscle fibers containing MyHC IIb increased in the posterior-intermediate and posterior-deep regions between 7 and 14 days (ANOVA, P &lt; .05). The increase in the proportion of MyHC IIb fibers in the bite opening group did not occur when compared to the control group (P &lt; .05). In addition, after 14 days of bite opening, the proportion of fibers positive for MyHC IIa was decreased in the anterior region compared to control masseter muscles. Muscle fiber diameter remained unchanged in both groups (experimental and control) and over time (P &gt; .10). Conclusion: These data are consistent with a selective plasticity of the expression of MyHC IIb protein in the deep regions of the male masseter muscle in response to a clinically relevant VDO increase.

scholarly journals Morphometric evaluation of condylar cartilage of growing rats in response to mandibular retractive forces

2013 ◽  
Vol 18 (4) ◽  
pp. 113-119 ◽  
Author(s):  
Milena Peixoto Nogueira de Sá ◽  
Jacqueline Nelisis Zanoni ◽  
Carlos Luiz Fernandes de Salles ◽  
Fabrício Dias de Souza ◽  
Uhana Seifert Guimarães Suga ◽  
...  
Keyword(s):  
Functional Class ◽  
Control Group ◽  
Class Iii ◽  
Condylar Cartilage ◽  
Time Intervals ◽  
Undifferentiated Cells ◽  
Male Wistar Rats ◽  
Mandibular Retrusion ◽  
Experimental Group ◽  
Morphometric Evaluation

INTRODUCTION: The mandibular condylar surface is made up of four layers, i.e., an external layer composed of dense connective tissue, followed by a layer of undifferentiated cells, hyaline cartilage and bone. Few studies have demonstrated the behavior of the condylar cartilage when the mandible is positioned posteriorly, as in treatments for correcting functional Class III malocclusion. OBJECTIVE: The aim of this study was to assess the morphologic and histological aspects of rat condyles in response to posterior positioning of the mandible. METHODS: Thirty five-week-old male Wistar rats were selected and randomly divided into two groups: A control group (C) and an experimental group (E) which received devices for inducing mandibular retrusion. The animals were euthanized at time intervals of 7, 21 and 30 days after the experiment had began. For histological analysis, total condylar thickness was measured, including the proliferative, hyaline and hypertrophic layers, as well as each layer separately, totaling 30 measurements for each parameter of each animal. RESULTS: The greatest difference in cartilage thickness was observed in 21 days, although different levels were observed in the other periods. Group E showed an increase of 39.46% in the total layer, reflected by increases in the thickness of the hypertrophic (42.24%), hyaline (46.92%) and proliferative (17.70%) layers. CONCLUSIONS: Posteriorly repositioning the mandible produced a series of histological and morphological responses in the condyle, suggesting condylar and mandibular adaptation in rats.

scholarly journals Functional changes in the temporomandibular joint mechanoreceptors associated with experimentally induced condylar resorption in rats

2020 ◽  
Vol 90 (6) ◽  
pp. 831-836
Author(s):  
Satomi Naito ◽  
Chiho Kato ◽  
Tadachika Yabushita ◽  
Takashi Ono
Keyword(s):  
Temporomandibular Joint ◽  
Single Unit ◽  
Compressive Force ◽  
Firing Frequency ◽  
Control Group ◽  
Gasserian Ganglion ◽  
Firing Threshold ◽  
Functional Changes ◽  
Force Loading ◽  
Experimentally Induced

ABSTRACT Objectives To evaluate the influence of experimentally induced progressive condylar resorption (PCR) on temporomandibular joint (TMJ) mechanoreception. Materials and Methods Twenty 13-week-old male albino Wistar rats were divided equally into control and PCR groups. A compressive force was loaded on the left TMJ of PCR group rats to induce condylar resorption. Single-unit activities of TMJ mechanoreceptors were also induced through passive jaw movement. Recording was performed for the left Gasserian ganglion at 3 days and 1 week after the establishment of PCR group. The effects of PCR on TMJ units were assessed by measuring the firing threshold, maximum instantaneous firing frequency, and average firing frequency. Results Compared with the control group, there were no significant differences in the firing threshold of the PCR group after 3 days. The thresholds were significantly higher 1 week after compressive force loading on the condyle. The maximum instantaneous firing frequencies and the average firing frequencies showed no significant differences after 3 days. However, these were significantly lower 1 week after compressive force loading. Conclusions The findings suggest that compressive force loading on the condyle may influence the function of TMJ mechanoreceptors.

scholarly journals Forced internal desynchrony induces cardiometabolic alterations in adult rats

2019 ◽  
Vol 242 (2) ◽  
pp. 25-36
Author(s):  
Isis Gabrielli Barbieri de Oliveira ◽  
Marcos Divino Ferreira Junior ◽  
Paulo Ricardo Lopes ◽  
Dhiogenes Balsanufo Taveira Campos ◽  
Marcos Luiz Ferreira-Neto ◽  
...  
Keyword(s):  
Locomotor Activity ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Metabolic Response ◽  
Hepatic Metabolism ◽  
Control Group ◽  
Dark Cycle ◽  
Adult Rats ◽  
Internal Desynchronization ◽  
Male Wistar Rats ◽  
Experimental Group

Disruptions in circadian rhythms have been associated with several diseases, including cardiovascular and metabolic disorders. Forced internal desynchronization induced by a period of T-cycles of 22 h (T22 protocol) reaches the lower limit of entrainment and dissociates the circadian rhythmicity of the locomotor activity into two components, driven by different outputs from the suprachiasmatic nucleus (SCN). The main goal of this study was to evaluate the cardiovascular and metabolic response in rats submitted to internal desynchronization by T22 protocol. Male Wistar rats were assigned to either a control group subjected to a usual T-cycles of 24 h (12 h–12 h) or an experimental group subjected to the T22 protocol involving a 22-h symmetric light–dark cycle (11 h–11 h). After 8 weeks, rats subjected to the T22 exhibited desynchrony in their locomotor activity. Although plasma glucose and insulin levels were similar in both groups, desynchronized rats demonstrated dyslipidemia, significant hypertrophy of the fasciculate zone of the adrenal gland, low IRB, IRS2, PI3K, AKT, SOD and CAT protein expression and an increased expression of phosphoenolpyruvate carboxykinase in the liver. Furthermore, though they maintained normal baseline heart rates and mean arterial pressure levels, they also presented reduced baroreflex sensitivity. The findings indicate that circadian timing desynchrony following the T22 protocol can induce cardiometabolic disruptions. Early hepatic metabolism dysfunction can trigger other disorders, though additional studies are needed to clarify the causes.

Activation of Peripheral GABAA Receptors Inhibits Temporomandibular Joint–Evoked Jaw Muscle Activity

1999 ◽  
Vol 81 (4) ◽  
pp. 1966-1969 ◽  
Author(s):  
Brian E. Cairns ◽  
Barry J. Sessle ◽  
James W. Hu
Keyword(s):  
Receptor Antagonist ◽  
Temporomandibular Joint ◽  
Gabaa Receptors ◽  
Muscle Activity ◽  
Mustard Oil ◽  
Emg Activity ◽  
Dose Response Relationship ◽  
Jaw Muscle ◽  
Nociceptive Information ◽  
Masseter Muscles

Activation of peripheral GABAA receptors inhibits temporomandibular joint–evoked jaw muscle activity. We have previously shown that injection of mustard oil or glutamate into rat temporomandibular joint (TMJ) tissues, an experimental model of acute TMJ injury, can reflexly induce a prolonged increase in the activity of both digastric (jaw-opener) and masseter (jaw-closer) muscles. In this study, GABA was applied to the TMJ region by itself or in combination with glutamate, and the magnitude of evoked jaw muscle electromyographic (EMG) activity was measured. Application of GABA alone to the TMJ region did not evoke significant jaw muscle EMG activity when compared with normal saline controls. In contrast, co-application of GABA and glutamate into the TMJ region decreased the magnitude of glutamate-evoked EMG activity. This GABA-mediated inhibition of glutamate-evoked EMG activity followed an inverse dose-response relationship with an estimated median inhibitory dose (ID50) of 0.17 ± 0.05 (SE) μmol and 0.031 ± 0.006 μmol for the digastric and masseter muscles, respectively. Co-administration of the GABAA receptor antagonist bicuculline (0.05 μmol) but not the GABABreceptor antagonist phaclofen (0.05 or 0.15 μmol) reversed the suppressive actions of GABA, indicating that this action of GABA may be mediated by peripheral GABAA receptors located within the TMJ region. Our results suggest that activation of peripheral GABAA receptors located within the TMJ region could act to decrease the transmission of nociceptive information.

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