Dietary lupin protein lowers triglyceride concentrations in liver and plasma in rats by reducing hepatic gene expression of sterol regulatory element-binding protein-1c.

BACKGROUND

Recently, it has been shown that dietary lupin protein lowers plasma triglyceride concentrations in rats. In this study, we investigated the hypothesis that this effect is due to a downregulation of sterol regulatory element-binding protein (SREBP)-1c, a transcription factor that regulates the expression of lipogenic enzymes in the livers of rats.

METHODS

Two groups of 12 rats each were fed semisynthetic diets containing 200 g/kg of either casein (control group) or lupin protein from Lupinus albus for 22 days.

RESULTS

Rats fed the diet containing lupin protein had lower concentrations of triglycerides in the liver, plasma and VLDL + chylomicrons (p < 0.05). The concentration of protein in VLDL + chylomicrons was also lower in rats fed lupin protein than in rats fed casein (p < 0.05). The mRNA concentrations of SREBP-1c and fatty acid synthase in the liver were lower in rats fed lupin protein than in rats fed casein (p < 0.05). The mRNA concentrations of lipoprotein lipase in the liver did not differ between both groups of rats.

CONCLUSIONS

This study confirms that a protein isolated from L. albus is strongly hypotriglyceridemic in rats. It is shown for the first time that this effect is at least in part due to a downregulation of SREBP-1c in the liver which in turn leads to a reduction in hepatic fatty acid synthesis.