The Effects of Fertilized Egg Yolk Isolates on Anabolic and Catabolic Signaling in Skeletal Muscle

Abstract

Fortetropin, a bioactive ingredient derived from fertilized chicken egg yolk, augmented gains in muscle in trained humans compared to exercise alone. This study investigated the impact of Fortetropin on protein synthesis and protein degradation in rats after acute exercise. Male wistar rats were fed for 8 days with either 1.2 ml of tap water (control) or 0.39 g Fortetropin (MYOS Corp). Rats underwent an electrically-stimulated lower body unilateral exercise regimen. Muscles in the non-exercised and exercised limbs were harvested at 180 minutes following exercise and analyzed for gene and protein expression in myostatin, mTOR and ubiquitin signaling pathways. Activin IIB receptor mRNA was significantly lowered in the exercise + Fortetropin group, but not the exercise + control group indicating depression of the myostatin pathway via decreasing receptor expression (p<0.05). An increase in both Ubiquitin monomer protein expression and polyubiquitination were greater in the control + exercise, but not Fortetropin + exercise (p<0.05). The mRNA expression of Atrogin-1 was depressed in the Fortetropin + exercise compared to control + exercise (p<0.05). Phosphorylation status of 4EBP1, rp6, and p70S6K were increased for both groups. The Fortetropin + exercise resulted in elevations of these markers compared to the control (p<0.05). Fortetropin supplementation reduced mRNA expression of the myostatin receptor, Activin IIB. Fortetropin also appears to promote muscle growth via increasing anabolic (mTOR) and decreasing catabolic (ubiquitin) signaling.