並列タイトル等Effects of soft diet on temporomandibular joint of growing rats
一般注記Modern people tends to have soft food . Therefore experimentalstudies have been performed to examine unfavorable influences to growth ofmasticatory muscles and craniofacial bone induced by such a dietary habits.The aim of the present study was to clarify the effects of soft diet on thetemporomandibular joint (TMJ) in growing rats using thehistomorphometrical and immunohistochemical methods. Twenty-four maleWistar rats were weaned at age 21 days and were divided into control andexperimental groups. Control rats were fed a solid food and experimentalones fed a liquid food from 1 to 8 weeks. After injection with5-bromo-2’-deoxyuridine (BrdU), the animals were perfused with 4%paraformaldehyde solution and the whole heads were removed. Serialcoronal sections of TMJ were stained with Haematoxylin and Eosin or withBrdU-immunohistochemistry. Three dimensions and the thickness ofcartilage layer of the TMJ were measured using histological sections, andcell proliferation in the TMJ was examined using immunostained sections.The height and width of the zygomatic process of mandibular fossa inexperimental group were smaller than in control group after 4 weeks. Thewidth and length of the condyle of experimental animals were also smallerthan those of controls after 4 weeks. In the mandibular fossa, articular zone(AZ) and hypertrophic zone (HZ) at 4 weeks and AZ and intermediate zone(IZ) at 8 weeks in the experimental groups were thinner than in the control.All zones at 4 weeks and AZ at 8 weeks of the condyle in the experimentalgroup were also thinner. The labeling indices of BrdU in IZ of themandibular fossa and of the condyle in the experimantal groups were lowerthan in the controls at 4 weeks and at 1 and 4 weeks, respectively. Thesefindings suggest that the soft food-intake inhibits the growth of the TMJ ofrats, due to low proliferative activity of cells in IZ.
最近では軟らかい食事を好んで摂取している現代人が増加している.このような食習慣が咀嚼筋や顔面骨格に与える影響を調べるため,実験的研究が行われてきた.本研究では,成長期ラットにソフトフードを継続的に摂取させた時,顎関節にどのような影響が及ぶのかを形態学的,免疫組織化学的に明らかにすることを目的とした.実験にはWistar系雄性ラット24匹を用い, 21日齢で離乳させた.離乳後,液状食（実験群）あるいは固形食（対照群）を与え, 1～8週間飼育した.飼育期間が終了した動物は5-bromo-2’-deoxyuridine（BrdU）を投与した後,4%パラホルムアルデヒド溶液にて灌流固定し,頭部を摘出した.以後通法に従って前頭断連続切片を作製した.切片にはヘマトキシリン・エオジン染色を施し,顎関節部の3次元的大きさ,および軟骨層の厚さについて組織計量を行った.また一部の切片にはBrdU免疫染色を施し,顎関節部の細胞増殖活性を測定した.組織計量学的には,実験群の下顎窩相当部頬骨突起は4週（高径）と8週（幅径、高径）で,下顎頭は4週（幅径）と8週（幅径、長径）で対照群よりも小さかった.軟骨層の厚さに関しては,下顎窩では4週のarticular zone(AZ)とhypertrophic zone(HZ), 8週のAZとintermediate zone(IZ)で,下顎頭では4週の3層全てと8週のAZで実験群の方が菲薄であった.免疫組織化学的には, BrdU陽性細胞のほとんどはIZに認められた.BrdU陽性率では対照群より実験群が概して低く,下顎窩では4週,下顎頭では1週と4週で有意差が認められた.以上の結果から成長期におけるソフトフード摂取はラット顎関節の成長を阻害することが明らかとなり,これにはIZ中の細胞増殖活性低下が関連していると考えられた.
(主査) 教授 土門 卓文, 教授 鄭 漢忠, 准教授 高橋 茂, 講師 上田 康夫
歯学研究科（口腔医学専攻）
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受理日（W3CDTF）2016-03-01T12:53:35+09:00
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