Histochemical responses of skeletal muscle satellite cells to heat stress in rats

Abstract

It is considered that muscle satellite cells are myogenic precursor cells and are responsible for the postnatal growth and regeneration of skeletal muscles. Recently, we have discovered that heat stress induces skeletal muscle hypertrophy in vitro and in vivo. Our results suggest that heat stress activates Akt signaling pathway and facilitates the proliferation and differentiation of satellite cells. However, it is still unclear how the heat stress influences the morphological properties (satellite cell activation) of skeletal muscle. Therefore, the current study was performed to investigate the responses of skeletal muscles to heat stress by using histochemical techniques. Wistar strain male rats were divided into two groups; control and heat stress. Heat stress group was exposed to environmental heat stress (41°C for 60 min). Soleus muscle was dissected from both hindlimbs 1 and 7 days after heat exposure. Administration of 10% Evans blue dye (100 μl/100 g BW, intravenously) were performed to some of the rats in both groups 24 hr prior to the dissection of muscles. A few muscle fibers in which accumulated Evans blue dye were noted in heat stress, but not in control, group. The data suggested that activation of satellite cells was induced following heat exposure. [Jpn J Physiol 54 Suppl:S119 (2004)]