大豆乳酸菌発酵物はNrf2/SHP経路の活性化を介して血中および肝臓中脂質を減少させる

Abstract

Lactobacillus fermented soybean (FS) is expected to affect the lipid metabolism by inhibiting lipogenesis and lipid absorption. In the present study, we investigated the effect of FS on lipid metabolism in rats fed a high fat diet. Male Sprague-Dawley rats, aged 5 weeks, were randomly divided into 3 groups (n = 6 each) as follows: CO (40% high fat diet), SOY (high fat diet including 5% non-fermented soybean powder) and FS (high fat diet including 5% FS powder). After 4 weeks, there were no significant differences in the body weight, food intake and tissue weights (liver, perirenal and epididymal fat) among the 3 groups. Plasma and hepatic triglyceride levels were significantly decreased in FS intake. On the other hands, fecal triglyceride was not significantly effect in FS intake. Next, we analyzed the expression of key genes controlling TAG metabolism in the liver. Hepatic GPAT gene expression was significantly decreased in FS intake. However, hepatic ACC, SREBP-1c and ChREBP gene expression was not significantly effect in FS intake. Hepatic SHP gene expression was significantly increased in FS intake, and there was a negative correlation between the SHP and GPAT gene expression. Thus, these results suggest that the decreasing in hepatic GPAT gene expression is associated with SHP. Nrf2 is one of the transcriptional factors regulating SHP expression. Thus, we investigated whether Nrf2 activity was enhanced by FS intake. Nrf2 protein and gene expression were not significantly effect in FS intake. Conversely, nuclear Nrf2 abundance ,increased in FS intake. Furthermore, hepatic GSTT3, Nrf2 target gene, were significantly increased in FS intake. These results indicate that FS reduces the plasma and hepatic lipids via activation of Nrf2/SHP pathway.