Despite over 50 years of research, a comprehensive understanding of how intramuscular triglyceride (IMTG) is stored in skeletal muscle and its contribution as a fuel during exercise is lacking. Immunohistochemical techniques provide information on IMTG content and lipid droplet (LD) morphology on a fibre type and subcellular-specific basis, and the lipid dye Oil Red O (ORO) is commonly used to achieve this. BODIPY 493/503 (BODIPY) is an alternative lipid dye with lower background staining and narrower emission spectra. Here we provide the first quantitative comparison of BODIPY and ORO for investigating exercise-induced changes in IMTG content and LD morphology on a fibre type and subcellular-specific basis. Estimates of IMTG content were greater when using BODIPY, which was predominantly due to BODIPY detecting a larger number of LDs, compared to ORO. The subcellular distribution of intramuscular lipid was also dependent on the lipid dye used; ORO detects a greater proportion of IMTG in the periphery (5 μm below cell membrane) of the fibre, whereas IMTG content was higher in the central region using BODIPY. In response to 60 min moderate-intensity cycling exercise, IMTG content was reduced in both the peripheral (− 24%) and central region (− 29%) of type I fibres (P < 0.05) using BODIPY, whereas using ORO, IMTG content was only reduced in the peripheral region of type I fibres (− 31%; P < 0.05). As well as highlighting some methodological considerations herein, our investigation demonstrates that important differences exist between BODIPY and ORO for detecting and quantifying IMTG on a fibre type and subcellular-specific basis.

尽管进行了 50 多年的研究，但仍缺乏对肌内甘油三酯 (IMTG) 如何储存在骨骼肌中及其作为运动燃料的贡献的全面了解。免疫组织化学技术可根据纤维类型和亚细胞特异性提供有关 IMTG 含量和脂滴 (LD) 形态的信息，并且通常使用脂质染料油红 O (ORO) 来实现这一点。BODIPY 493/503 (BODIPY) 是一种替代的脂质染料，具有较低的背景染色和较窄的发射光谱。在这里，我们提供了 BODIPY 和 ORO 的第一次定量比较，用于在纤维类型和亚细胞特异性基础上研究运动引起的 IMTG 含量和 LD 形态的变化。使用 BODIPY 时，IMTG 含量的估计值更高，这主要是由于 BODIPY 检测到大量 LD，与ORO相比。肌内脂质的亚细胞分布也取决于所使用的脂质染料；ORO 在纤维的外围（细胞膜下方 5 μm）检测到更大比例的 IMTG，而使用 BODIPY 在中心区域检测到 IMTG 含量更高。在进行 60 分钟中等强度的自行车运动后，I 型纤维的外围 (- 24%) 和中心区域 (- 29%) 的 IMTG 含量均降低。P  < 0.05）使用 BODIPY，而使用 ORO，IMTG 含量仅在 I 型纤维的外围区域减少（- 31%；P  < 0.05）。除了在此强调一些方法论方面的考虑外，我们的调查还表明，BODIPY 和 ORO 之间存在重要差异，用于在纤维类型和亚细胞特异性基础上检测和量化 IMTG。