Investigation for Activators of Adipocyte Differentiation in Feed for Beef Cattle

Abstract

Beef marbling is an important trait of meat quality, which contributes directly to the value of beef especially in the Japanese market. The development of beef marbling was closely associated with an increase in the number of adipocytes, that is, adipocyte differentiation in the skeletal muscle. Peroxisome proliferator-activated receptorγ (PPARγ) is a ligand-dependent transcription factor that directly activates the expression of adipocyte-specific genes, and is universally accepted as the master regulator for adipocyte differentiation. Through screening for natural PPARγ activator in feed using the PPARγ luciferase reporter assay, the ethanol extracts of sake lees, soy sauce lees, vinegar lees, and beer lees, and soy sauce oil activated PPARγ. Treatment with the ethanol extracts of these lees materials enhanced some markers of adipocyte differentiation such as glycerol-3-phosphate dehydrogenase activity and triglyceride accumulation in 3T3-L1 cells. These results suggest that these lees materials possess PPARγ activators. Moreover, according to the results of the sequential fractionation assay, we confirmed that PPARγ-activate factors in soy sauce oil were different from linoleic acid, originated from soy bean oil.