Saccharomyces cerevisiae-Fermented Salmon Placental Protein Inhibits Muscle Loss in a Mouse Model of Sarcopenia

Addressing sarcopenia and frailty in aging populations is crucial for improving quality of life and reducing healthcare dependence among these patients. Although no specific drugs have been approved for treating sarcopenia, protein supplements rich in branched-chain amino acid (BCAA) have been reported to increase muscle mass and function in elderly individuals. Fermentation of salmon placenta protein is an effective approach to improve BCAA content compared to previous sarcopenia-related protein supplements. Therefore, this study aimed to evaluate BCAA content through salmon placenta protein (Sal) fermented with Saccharomyces cerevisiae (F-Sal), analyze the expression of muscle-forming genes in C2C12 myoblasts in vitro, measure the weight gain of quadriceps femoris and gastrocnemius muscle, measure the volume and thickness of gastrocnemius muscle, and measure the expression of biomarkers related to sarcopenia in quadriceps femoris and gastrocnemius muscle in a mouse model of sarcopenia. Here, we report for the first time that salmon placental extracts (Sal) fermented with S. cerevisiae (F-Sal) exhibit drastically elevated levels of BCAA, including leucine, isoleucine, and valine, and ameliorated the conditions of sarcopenia in both in vitro and in vivo sarcopenia models. When the addition of Sal or F-Sal to cultured C2C12 myoblasts with dexamethasone-induced sarcopenia, the expression level of the muscle-forming gene MyoD was significantly increased in F-Sal compared to Sal (p < 0.01), and the expression level of the muscle-degrading gene MuRF1 was significantly decreased in F-Sal compared to Sal (p < 0.01). In a mouse model of sarcopenia, oral administration of F-Sal for 14 days following dexamethasone treatment increased muscle weight and the expression of muscle-forming genes while mitigating muscle loss and reducing the expression of muscle-degrading genes in both the quadriceps femoris and gastrocnemius muscles. These findings provide a therapeutic basis for treating muscle weakness in patients with end-stage disease as well as sarcopenia-related muscle conditions in elderly by improving BCCA content with S. cerevisiae -fermented salmon placental protein (F-Sal).