الفهرس 
AcknowledgementsOnly 14 pages are availabe for public view
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Abstract
Summary br Swallowing is a highly complex and coordinated reflex regulated through the central nervous system to elicit a synchronized muscle contraction (Miller, 2008). The swallow reflex prevents the aspiration of food and liquid into the trachea/lungs and the subsequent development of life-threatening pneumonia (Prasse and Kikano 2009). Pharyngeal muscles are an essential component of the swallow reflex. Pharyngeal muscles contract to create the proper pressures required to propel bolus through the pharynx and UES, and to shape the airway to modulate resonance during voice and speech production (Mu and Sanders 2001). br In fact, the pharyngeal stage of swallowing is involuntary, and is the most rapid and complex phase in the entire deglutition process that requires bilateral sequenced activation and inhibition of more than 30 pairs of different muscles of the mouth, pharynx, larynx and esophagus (Cunningham and Jones 2003). br Seven major muscles are responsible for pharyngeal contraction when swallowing. These muscles arise during vertebrate development -#102;-#114;-#111;-#109; the third and fourth pharyngeal arches and are comprised of the stylopharyngeus, palatopharyngeus, salpingopharyngeus and the superior, middle and inferior pharyngeal constrictor muscles. The inferior pharyngeal constrictor can be subdivided into the cricopharyngeus and the thyropharyngeus muscles. Despite the critical nature of these muscles, few studies have analyzed the effects of age and disease on pharyngeal muscles as a -#103;-#114;-#111;-#117;-#112; (Randolph et al 2014) Pharyngeal muscles functional abnormalities due to aging or some neurological diseases may result in risks of malnutrition and/or aspiration pneumonia (Molfenter and Steele 2013). br Extensive research work is also needed on structure-to-function relationships in these muscles. Biochemical research will hopefully bridge the gap between the biologic processes of these muscles and clinical diagnosis and treatment of disorders related to muscle function (Hoh 2005). br In fact, muscles use calcium (Ca2+) as their main regulatory and signaling molecule. Also, muscle plasticity is highly dependent on the Ca2+ handling system (Berchtold et al 2000). Alterations in the Ca2+ handling system (Ca2+ release, storage, uptake, transport and intracellular calcium) have been implicated in many types of pathological processes (Chemaly et al 2013). br Sarcoplasmic reticulum Ca2+ ATPase (SERCA) membrane proteins play central roles in calcium regulation. It has a dual function: to induce and maintain muscle relaxation by pumping calcium -#102;-#114;-#111;-#109; the sarcoplasm to luminal spaces in the sarcoplasmic reticulum (SR) so that it lowers sarcoplasmic Ca2+ concentration, and at the same time to restore SR luminal calcium reservoir necessary for muscle contraction and for bringing calcium levels down to baseline levels following release. In actuality, the major proteins stand for contraction and relaxations in skeletal muscle are the SERCA and the myosin (MHC) proteins (Kjellgren and Ryan 3003). SERCA plays the main role in the muscle contraction/relaxation cycle, while MHC in muscle fibres regulates the contraction force and velocity and called either slow-contracting, fatigue resistant to fast-contracting, fatigable (Periasamy and Kalyanasundaram 2007). In addition, the difference between fast and slow muscles fibers in contraction and relaxation times is linked to the different isoforms’ expression of SERCA (SERCA 1 and SERCA 2) and/or MHC (MHC I and MHC II). More specifically, fast fibers express SERCA 1 and MHC II while slow fibers express SERCA 2 and MHC I (Hoh 2005). br Fast muscle fibres (type II) are recruited for short maximal efforts with fast contraction speeds, take a shorter amount of time than type I fibers to reach peak tension and are easy fatigable, therefore, makes them ideal for higher intensity tasks. In contrast, slow muscle fibres (type I) have a long time to peak tension, a slow contraction speed and are highly resistant to fatigue; therefore, during muscle function they are responsible for low intensity, repetitive tasks. Thus, muscle regions with a high proportion of fast type II fibres facilitate rapid and phasic movements, whereas those with a high proportion of type I fibres are generally involved in postural adjustments. Therefore, the proportions and distribution patterns of MHC- and SERCA-containing fibres in muscle are closely related to muscle functions (Periasamy and Kalyanasundaram 2007). br Although there is an abundance of literature on the physiology of normal functioning hypopharyngeal muscles. However, there is scant literature on contractile properties including Ca+2 handling proteins of these muscles and changes in pathological disorder. Not only is it necessary to know how a muscle normally functions, it is also important to understand why it functions in a particular way and under what circumstances would changes in muscle structure and composition negatively affect muscle function. Understanding the potential changes in contractile properties of the muscles fibers will enable swallow researchers and physician to base the design and development of new diagnosis and treatment. br Composition of slow, fast and hybrid fibres of pharyngeal muscles, associated with pharyngeal movements and regulation, has been rarely studied. Thus, the present study aimed to identify expression of SERCA, MHC, and hybrid isoforms in different pharyngeal muscles of young and aged rats as well as human. Because of the lack of available information on the expression and role of SERCA isoforms in pharyngeal muscles. Isoform expression profiles of SERCA, MHC and hybrid isoforms among were immunohistochemically evaluated in rat and human. br Several difficulties were faced in the present research through different techniques till finishing the results. The first was to identify the cricopharyngus muscle. After microscopic dissection study, hypopharyngeal muscle was understood and become easier to identify in IHC study and SERCA and MHC expression and localization quantification more accurate. The current gross microscopic results were similar to Kobler et al 1994, so it is better to name rat cricopharyngus as semicircular. Second, frozen section IHC was difficult due to high autofluorescence which disappeared after shift to paraffin embedded block. Finally, PCR was not continued due to inadequate fund. br The different proportions of slow and fast muscle fibers by MHC and SERCA isoforms in pharyngeal muscles in rat were presented. The pharyngeal muscles are mainly fast twitch muscles (SERCA1 and MHCII), whereas expression of slow fibres (SERCA2 and MHCI) was low, but different depending on muscle components. SC showing a special pattern of SERCA 2 distribution. The inner layer expresses more SERCA2 and hybrid fibres than the outer layer. Pharyngeal muscles in aged rats showed increased hybrid fibers and SERCA2. So, the aging is associated with alterations in pharyngeal muscle contractile properties. br Cervical esophagus, palatopharyngus and soft palate muscles predominantly expressed fast twitch fibers. SERCA 2 expression in these muscles may have role in slow tonic action as closure of UES and maintain airway patency respectively. These data will also be a baseline in a forthcoming analysis of the soft palate muscles -#102;-#114;-#111;-#109; patients suffering -#102;-#114;-#111;-#109; obstructive sleep apnea syndrome (OSAS) and neuromuscular disorder. br Human thyropharyngeus also showed a higher portion of fast fibres compared to cricopharyngeus. This distribution difference may be attributed primary to different motor functions of each muscle. br Thus, abundance of fast fibres and hybrid fibres are differentially expressed depending on muscle components and layers as well as age-related remodeling are the main results in the current study. The unique data presented in this study on SERCA isoform expressions in both rats and humans suggest an ability to handle calcium changes according functional demands. It may assist in better understanding of the physiological functions of pharyngeal muscle in speech and swallowing, and their effects on pathological conditions. br Conclusion br In this study, the different proportions and patterns of slow and fast muscle fibers represented by MHC and SERCA isoforms in pharyngeal muscles in rat and human through immunohistochemistry were demonstrated. br Based on rigorous examination and comparative analyses of the obtained results, the following conclusions was drawn: br • The frozen section is not suitable for studying IHC for SERCA and carry several technical difficulties including autoflorescence and high background noise br • Semicircular muscle (SC) could not identified except after microscopic anatomical study br • The present study confirms previous studies in rat as regard MHC expression. br • According to the very recent knowledge and publications, the present finding related to SERCA was not previously reported. These were : br a) SERCA 1 and SERCA 2 isoforms were expressed in all pharyngeal, palatal and CE muscles in young and old rats. These muscles are predominately fast-twitch muscles with predominantly expressed SERCA1 and MHCII (fast fibers). br b) Rat SC muscle shows regional variations as the inner muscle layer are preponderance type I (slow inner layer SIL) and an outer layer of type II (fast outer layer (FOL)). br c) Aging was associated with an increase of SERCA2 and hybrid fibers in pharyngeal muscles explaining slowing of swallow that occur with aging. br • In humans, CP muscle has higher portions of slow muscle (SERCA2) and hybrid (SERCA1 and SERCA2) fibers in comparison with TP muscles. This has not been previously reported br Moreover, the present study suggests the functional importance of SERCA isoforms and their expression and distribution in rat and human pharyngeal muscles.