Folliculin Interacting Protein 1 (FNIP-1) expression and capillary density in gastrocnemius muscle tissue of mice after biological maturation period

Introduction: The biological maturity period is the time or tempo of progress toward adulthood or maturity. The hormonal fluctuations play an important role in changing the characteristics of human body tissues during the biological maturity period. However, changes in tissue characteristics during biological maturity period have not been revealed. Skeletal muscle tissue is one of those believed to experience changes. Muscle fibers are thought to experience switching types from type 2 muscle fibers to type 1 muscle fibers. The transition of muscle fibers from type 2 to type 1 requires miR-499 activity from the expression of the Myh7b gene. MiR-499 directly inhibits FNIP-1. However, the biological maturity period of changing FNIP-1 expression has not been confirmed. Objective: This study aimed to analyse the effect of the biological maturity period on FNIP-1 expression and capillary density in the gastrocnemius muscle. Methodology: Thirty-six male mice were divided into mature groups aged eight weeks and immature groups aged four weeks. This study analyzed FNIP-1 and capillary density gastrocnemius muscle of mice using immunohistochemistry. Results: FNIP-1 expression test showed higher in immature mice than mature mice. In comparison, the capillary density test and endurance showed higher expression in mature mice than in immature mice. Conclusion: This study concludes maturation was characterized by a low distribution of FNIP-1 expression in the gastrocnemius muscle and a longer duration ability to run on the treadmill. Unfortunately, the capillary density was not a specific mark to determine maturation in mice.