الفهرس | Only 14 pages are availabe for public view |
Abstract Aim: The aim of the study was to evaluate the effect of posterior teeth extraction on type of intrinsic muscles’ fibers of the tongue via histological, histomorphometric, gene expression analysis, and ultrastructure via transmission electron microscope. Methodology: The study was carried out on 28 healthy male albino rats weight range 150 to 200 gm, fed with standard diet pellets and tap water ad libitum. 14 rats had bilateral mandibular molars extraction and 14 rats were used as control. Animals were randomly divided as following, group I: included 7 healthy male rats, that were not subjected to extraction and euthanized after 4 weeks, group II: included 7 healthy male rats, that were not subjected to extraction and euthanized after 8 weeks, group III: included 7 healthy male rats, that were subjected to bilateral mandibular molars extraction and euthanized after 4 weeks and group IV: included 7 healthy male rats, that were subjected to bilateral mandibular molars extraction and euthanized after 8 weeks. All 28 rats were euthanized either at 4 weeks (group I &group III) or at 8 weeks (group III &group IV) by decapitation. Tongues from 28 rats were dissected for histological, histomorphometic, gene expression analysis, and ultrastructure examination via transmission electron microscope. Results: The histological examination of group III showed significant deterioration in tongue muscles as compared to other groups where, areas of spacing between muscle bundles, increased perimysium connective tissue, together with dilated and congested blood vessels were detected. Upon long duration adaptation, group IV showed improvement in histological features of muscles together with signs of hypertrophy in comparison to the other groups. Morphometric analysis revealed a significant increase in (mean total area percent of muscle fibers, area of single muscle fiber, perimeter of single muscle fiber and minimum Feret’s diameter) in group IV in addition to significant decrease in number of inflammatory cells as compared to group III. Additionally, transmission electron microscopic imaging revealed mitochondrial degeneration together with a statistically significant increase in length of sarcomere and length of I-band in group III (4 weeks extraction). Further a statistically significant increase in (length of sarcomere, width of sarcomere, length of I-band and width of Z-line) in addition to Cox IV gene and PGC-1 alpha gene expression was observed in group IV (8 weeks extraction group) as compared to the other groups. Conclusions: The current study revealed that bilateral mandibular molar extraction had a great impact on intrinsic tongue muscles. We observed that 4 weeks following bilateral extraction of mandibular molars in albino rats was associated with altered mechanical loading on the tongue muscles inducing inflammatory response and muscle atrophy. While 8 weeks post extraction muscle adaptation with hypertrophy took place as evident by histological findings additionally, shift in muscle fiber type to slow more fatigue resistant type was clearly evident by elevation of Cox IV gene and PGC-1 alpha gene expression in intrinsic muscles of the tongue. Key words: Tongue Intrinsic Muscles ,Extraction ,PGC-1 alpha ,Cox IV , Transmission electron microscope , PCR. |