Effect of Obesity on the Structure and Myoglobin Distribution Within the Lingual Muscles of the Adult Male Albino Rats with Reference to Obstructive Sleep Apnea Syndrome

Document Type : Original Article

Authors

1 Department of Anatomy, Faculty of Medicine, Ain Shams University.

2 Department of Anatomy, Faculty of Medicine, Ain Shams University

Abstract

Background: Obesity is recognized as a worldwide health problem. Recently, the prevalence of obesity and concern about its impact on public health has grown dramatically. Obstructive Sleep Apnea Syndrome (OSAS) is the most common type of sleep apnea and the most typical individuals with OSAS suffer from obesity. Maintenance of patent upper airway depends on the dilating forces of the lingual muscles especially the genioglossus muscle which is the principal protrudor muscle of the tongue. Aim of the work: To find out the impact of obesity on the lingual muscles. Structural changes that occur in the tongue musculature in obese adult albino rats were investigated using light and transmission electron microscopy. Moreover, the state of lingual muscles oxygenation was examined through immune-staining of muscular myoglobin distribution. Materials and Methods: Three month-old Adult male Albino rats 200 gm body weight were used in the study. Animals were purchased from the Research Unit and Bilharzial Research Center of Faculty of Medicine, Ain Shams University. Rats were divided into two groups (5animals/group). Group I: Control group: Rats were fed a regular diet (protein: Fat: Carbohydrate= 29:13:58, 343 kcal/ 100 g). Group II: Obesity group: Rats were fed a high-fat diet (protein: Fat: Carbohydrate= 20: 57: 23, 508 kcal/ 100 g). After three months, the average weight of the control group was about 312±10 gm, while obesity group was about 730±20 gm. Rats were sacrificed and extracted tongue specimens were processed for light and transmission electron microscopy. Paraffin sections were also immunostained with anti-myoglobin antibody. Results: Light microscopic examination of lingual muscles of the obese group revealed fatty infiltration, degeneration and necrosis. In addition, congestion of blood vessels and infiltration with mononuclear cellular infiltrate was detected. Transmission electron microscopic investigation showed distortion in the arrangement and destruction of myofibrils and myofilaments. Swelling, apparent increase in number, and distorsion of internal cristae of the mitochondria were observed in obese group tongue muscles versus the control group. Immunohistochemistry for myoglobin revealed weak reaction in obese group compared with the control group. Conclusion: The present work declared that high-fat diet feeding responsible for rat’s obesity induced fat deposition, structural damage, inflammatory cellular infiltration and decreased myoglobin distribution inside lingual myofibres which may interfere with their contractile function. The present results may partially explain the close relationship between obesity and incidence of OSAS.

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