Objective: The Reg I gene is expressed during regeneration of various tissues but there are no studies showing its expression in skeletal muscle. The aim of our study was to explore the expression of Reg I gene in healthy skeletal muscles and to define the time course of Reg I gene up- and down-regulation during muscle regeneration after muscle injury in the rat slow and fast skeletal muscle. Material and methods: In 2-month-old Wistar rats, the regeneration process was induced in slow (musculus soleus, SOL) and fast (musculus extensor digitorum longus, EDL) types of skeletal muscle. Muscle degeneration/regeneration was induced by injection of local anesthetic (0.5% bupivacain). The immunohistochemistry and western blot analysis were performed for detection and quantification of Reg I protein in regenerating skeletal muscles after 1, 2, 3, 4, 5, 6, 7, 10 and 15 days of regeneration. Results: Reg I gene was not expressed in adult, healthy SOL and EDL muscles while its expression was induced during the process of muscle regeneration (in both SOL and EDL). The peak of Reg I expression was on third day following the start of the regeneration process. The Reg I gene was down-regulated by day 5 and disappears by day 6-7. Conclusions: The Reg I gene is not expressed in normal rat skeletal muscle. The rapid switching in Reg I gene expression takes place during the early stages of muscle regeneration in the rat SOL and EDL muscles.

Fundamental medical sciences