β-Conglycinin Lowers Very-Low-Density Lipoprotein-Triglyceride Levels by Increasing Adiponectin and Insulin Sensitivity in Rats

The relationship between insulin sensitivity and the plasma triglyceride-lowering effect induced by conglycinin was investigated. Male Wistar rats (19 weeks old) were fed diets containing casein, soy protein isolate, or beta-conglycinin for 4 weeks. In oral glucose administration, the beta-conglycinin-fed rats showed a significant decrease in the area under the glucose curve (0-60 min) as compared with the casein-fed rats. The hypoglycemic effect was significantly higher in the beta-conglycinin-fed rats than in the casein-fed rats at 30 min after intraperitoneal insulin injection. The liver sterol regulatory element-binding-protein-1 mRNA expression level was significantly lower and the plasma adiponectin concentration was significantly higher in the beta-conglycinin-fed rats than in the casein-fed rats. The hypotriglyceridemic effect of beta-conglycinin depended on a significant decrease in the concentration of very-low-density-lipoprotein triglycerides. These results indicate that beta-conglycinin increases adiponectin levels and improves glucose tolerance. The ability of beta-conglycinin to lower plasma lipid levels might be due to increased insulin sensitivity of the liver.