INSERM UMR1093-CAPS, Université Bourgogne Franche-Comté, UFR Des Sciences de Santé, 21000, Dijon, France.
Département Génie Biologique, IUT, 21000, Dijon, France.
Sci Rep. 2022 Jan 10;12(1):311. doi: 10.1038/s41598-021-03740-8.
BDNF (brain-derived neurotrophic factor) is present in skeletal muscle, controlling muscular metabolism, strength and regeneration processes. However, there is no consensus on BDNF cellular source. Furthermore, while endothelial tissue expresses BDNF in large amount, whether endothelial cells inside muscle expressed BDNF has never been explored. The aim of the present study was to provide a comprehensive analysis of BDNF localization in rat skeletal muscle. Cellular localization of BDNF and activated Tropomyosin-related kinase B (TrkB) receptors was studied by immunohistochemical analysis on soleus (SOL) and gastrocnemius (GAS). BDNF and activated TrkB levels were also measured in muscle homogenates using Western blot analysis and/or Elisa tests. The results revealed BDNF immunostaining in all cell types examined with a prominent staining in endothelial cells and a stronger staining in type II than type I muscular fibers. Endothelial cells but not other cells displayed easily detectable activated TrkB receptor expression. Levels of BDNF and activated TrkB receptors were higher in SOL than GAS. In conclusion, endothelial cells are an important and still unexplored source of BDNF present in skeletal muscle. Endothelial BDNF expression likely explains why oxidative muscle exhibits higher BDNF levels than glycolytic muscle despite higher the BDNF expression by type II fibers.
脑源性神经营养因子（BDNF）存在于骨骼肌中，控制肌肉代谢、力量和再生过程。然而，BDNF 的细胞来源尚未达成共识。此外，尽管内皮组织大量表达 BDNF，但肌肉内的内皮细胞是否表达 BDNF 尚未得到探索。本研究旨在对大鼠骨骼肌中 BDNF 的定位进行全面分析。通过对比目鱼肌（SOL）和腓肠肌（GAS）进行免疫组织化学分析，研究了 BDNF 和激活的原肌球蛋白相关激酶 B（TrkB）受体的细胞定位。还使用 Western blot 分析和/或 Elisa 试验测量了肌肉匀浆中的 BDNF 和激活的 TrkB 受体水平。结果显示，BDNF 在所有检查的细胞类型中均有免疫染色，在内皮细胞中染色明显，在 II 型肌纤维中染色更强。只有内皮细胞而不是其他细胞显示出易于检测的激活的 TrkB 受体表达。BDNF 和激活的 TrkB 受体的水平在 SOL 中高于 GAS。总之，内皮细胞是骨骼肌中 BDNF 的一个重要且尚未被探索的来源。内皮 BDNF 的表达可能解释了为什么氧化型肌肉的 BDNF 水平高于糖酵解型肌肉，尽管 II 型纤维的 BDNF 表达更高。
