大豆タンパク酵素分解物がin vivo およびin vitro でラットの脂肪組織に及ぼす効果に関する研究

Background A soy protein isolate(SPI)diet has been shown to lower of serum and hepatic lipids levels, and to suppress weight gain and body fat accumulation in rats with diet︱induced obesity compared to a casein(CAS)diet, by changing the metabolic functions of adipocytes. An enzymatic SPI hydrolysate(SPH)diet showed even greater physiological effects than the SPI diet in rodents. However, the mechanism underlying these effects remains unclear. This study investigated the effects of SPH diet on uncoupling protein︱1(UCP︱1) gene expression in rat adipocytes. Methods Experiment Ⅰ;Male Wistar rats(n=15)divided into CAS, SPI and SPH groups were maintained on a high︱sucrose diet containing 20% crude protein. After two weeks, tissue weights, and UCP︱1 gene expression in brown adipose tissue(BAT)were evaluated, as well as plasma lipid and adiponectin levels.Experiment Ⅱ;Primary visceral adipose cells, a model for white adipose tissue(WAT), were cultured in medium containing SPH, and UCP︱1 expression was measured. Results Experiment Ⅰ ;Animals on SPH diet had significantly higher levels of plasma adiponectin than those consuming CAS. SPH consumption induced the upregulation of UCP︱1 expression in BAT. Experiment Ⅱ;Adipocyte size was reduced, and UCP︱1 mRNA expression was upregulated in 100 g╱mL SPH as compared controls. Conclusions UCP︱1 mRNA expression was upregulated in animals consuming SPH;moreover, plasma adiponectin levels were elevated in these animals. These findings provide insight into the regulation of adipose tissue function, and could be useful for developing strategies to treat diet︱induced obesity.