THE PREFERENTIAL EXPRESSION PATTERN OF INSULIN-LIKE GROWTH FACTOR -1 AND ITS ISOFORMS IN THE GASTROCNEMIUS MUSCLE SUGGESTS PREFERENTIAL ROLES IN THE RUNNING AND SEDENTARY ADOLESCENTS
Noura M.S. Osman and Abdelrahman Mansour Abdelgaber*
Department of Human Anatomy and Embryology; Faculty of Medicine; Minia University, El Minia; Egypt.
Department of Health Sciences Sports; Faculty of Physical Education*, Minia University; El-Minia; Egypt
Insulin-like growth factor-I (IGF-I) is an essential skeletal muscle developmental regulator. It continues to escalate muscle growth throughout life. This study was done to investigate the expression of IGF-1 and its isoforms in the serum and in the gastrocnemius muscle of forty male adolescents in Minia University. They were divided equally into: group I: sedentary males. Group II: males who are running 1200 meters for 5 days/week for at least 5 years. Serum IGF-1 and its isoforms, namely IGF-1Ea and IGF-1Ec were done in the studied groups by ELISA. The expression of mRNA and protein in the gastrocnemius muscle biopsy for IGF-1 and its isoforms were done in the studied groups by semi-quantitative RT-PCR and western blot respectively. The results showed that the serum IGF-1 levels and the IGF-1 mRNA and protein in the gastrocnemius muscle were significantly higher in the runners than that of sedentary group. Serum IGF-1Ec isoform was significantly much higher in the runners than the resting group. IGF-1Ec on transcriptional and translational levels also showed significant higher levels in the running group. In contrast, serum and mRNA levels of IGF-1Ea showed non- significant differences between the two groups, while IGF-1Ea protein in the gastrocnemius muscle is higher in the resting group. These data confirmed a different expression profile for IGF-1 and its isoforms in the serum and in the gastrocnemius muscle at the mRNA and protein levels in the resting and the runners thus suggesting different role with skeletal muscle activity in adolescents.