Grillo Bruna Aléxia Cristofoletti, Rocha Lara C, Martinez Giovana Z, Pimentel Neto Jurandyr, Jacob Carolina Dos Santos, Watanabe Ii-Sei, Ciena Adriano P
Laboratory of Morphology and Physical Activity (LAMAF), Institute of Biosciences (IB), São Paulo State University (UNESP), Rio Claro, SP13506-900, Brazil.
Department of Anatomy, Institute of Biomedical Sciences -ICB III, University of São Paulo (USP), São Paulo, SP05508-900, Brazil.
Microsc Microanal. 2021 Apr 21:1-6. doi: 10.1017/S1431927621000313.
Obesity is characterized by excess adipose tissue and chronic inflammation and promotes extensive changes that can compromise skeletal muscles’ structural and functional integrity. Obesity can seriously impact the force transmission region between the muscle and the tendon, the myotendinous junction (MTJ). The present study aimed to investigate the plasticity of muscle fibers and MTJ regions in high-fat diet-induced obesity in rat tibialis anterior (TA) and soleus (SO) muscles. Wistar rats were divided into control and obese groups (induced by a high-fat diet). The samples of TA and SO muscles were prepared for histochemical and ultrastructural analysis (sarcomeres and MTJ projection). In the muscle fiber, similar adaptations were observed between the muscles of the smaller fiber (types I and IIa) in the obesity results. The MTJ region demonstrated different adaptations between the analyzed muscles. The TA–MTJ region has shorter ultrastructures, while in the SO–MTJ region, the ultrastructures were larger. We conclude that obesity induced by a high-fat diet promotes similar adaptation in the muscle fibers; however, in the MTJ region, the sarcoplasmatic projections and adjacent sarcomere demonstrate different adaptations according to distinct muscle phenotypes.
肥胖的特征是脂肪组织过多和慢性炎症，并会引发广泛的变化，这些变化会损害骨骼肌的结构和功能完整性。肥胖会严重影响肌肉与肌腱之间的力传递区域，即肌-肌腱连接点（MTJ）。本研究旨在探讨高脂饮食诱导的肥胖大鼠胫前肌（TA）和比目鱼肌（SO）中肌纤维和MTJ区域的可塑性。将Wistar大鼠分为对照组和肥胖组（由高脂饮食诱导）。制备TA和SO肌肉样本用于组织化学和超微结构分析（肌节和MTJ投影）。在肌纤维方面，肥胖结果显示，较小纤维类型（I型和IIa型）的肌肉之间观察到相似的适应性变化。MTJ区域在分析的肌肉之间表现出不同的适应性变化。TA-MTJ区域的超微结构较短，而在SO-MTJ区域，超微结构较大。我们得出结论，高脂饮食诱导的肥胖会促进肌纤维产生相似的适应性变化；然而，在MTJ区域，肌浆突和相邻肌节根据不同的肌肉表型表现出不同的适应性变化。
