Department of Animal Biology and Marine Ecology, University of Messina, Messina 98166, Italy.
Microsc Res Tech. 2010 Aug;73(8):797-802. doi: 10.1002/jemt.20822.
The mammalian hormone, leptin, is mainly synthesized in adipose tissue along with other tissues. Leptin plays a role in numerous processes such as in the control of food intake, homeostasis, immune function and reproduction. In this study, we detected and localized leptin immunoreactivity to the muscle of early juvenile sea bass (Dicentrarchus labrax) by Western blot analysis and immunohistochemistry. A leptin immunopositive band with a molecular weight of approximately 16 kDa, corresponding to mammalian leptin, was identified in trunk skeletal muscle homogenate. Furthermore, leptin immunopositive cells were detected in the endomysium of skeletal muscular fibers. These cells showed immunostained cytoplasmic granules and roundish and oval nuclei. The most intense immunostaining was observed in the endomysial space among the superficial red muscular fibers of the trunk. These findings suggest that in early juvenile sea bass, leptin is mostly produced by skeletal muscles. Therefore, during the developmental stage lacking adipose tissue, skeletal muscles can be considered an important source of leptin. As already suggested in mammals, we can hypothesize the potential roles of leptin not only in energy expenditure for muscle contraction but also during muscle differentiation and growth.
哺乳动物激素瘦素主要在脂肪组织以及其他组织中合成。瘦素在许多过程中发挥作用，如控制食物摄入、体内平衡、免疫功能和生殖。在这项研究中，我们通过 Western blot 分析和免疫组织化学检测到并定位了早期幼鱼（Dicentrarchus labrax）肌肉中的瘦素免疫反应性。在躯干骨骼肌匀浆中鉴定出分子量约为 16 kDa 的瘦素免疫阳性带，对应于哺乳动物瘦素。此外，在骨骼肌纤维的肌内膜中检测到瘦素免疫阳性细胞。这些细胞显示出免疫染色的细胞质颗粒和圆形或椭圆形核。在躯干浅红色骨骼肌纤维之间的肌内膜空间中观察到最强的免疫染色。这些发现表明，在早期幼鱼中，瘦素主要由骨骼肌产生。因此，在缺乏脂肪组织的发育阶段，骨骼肌可以被认为是瘦素的一个重要来源。正如在哺乳动物中已经提出的那样，我们可以假设瘦素的潜在作用不仅在于肌肉收缩的能量消耗，而且在于肌肉分化和生长。
