2003 Volume 49 Issue 6 Pages 442-446
Sesamin, a lignan in sesame seeds and sesame seed oil, and capsaicin, the pungent principle of hot red pepper, affect lipid metabolism. Sesamin specifically inhibits 15 desaturase activity in the Mortierella alpina fungus and rat liver microsomes, however, the effects of sesamin and capsaicin on mRNA expressions of Δ6 and Δ5 desaturases are not still clear. In this study, we investigated the effects of sesamin and capsaicin on the desaturation indexes of Δ6 [(γ-linolenic acid+dihomo-γ-linolenic acid)/linolenic acid, (GLA+DGLA)/LA] and Δ5 (arachidonic acid/DGLA, AA/DGLA) and mRNA expressions of Δ6 and Δ5 desaturases in rat primary cultured hepatocytes. To measure the mRNA expressions of Δ6 and Δ5 desaturase, hepatocytes were cultured in the presence of sesamin or capsaicin for 24 h. To investigate the Δ6 or Δ5 desaturation index, hepatocytes were cultured in the presence of LA or DGLA, respectively, with sesamin or capsaicin for 24 h. The fatty acid composition of the cells was measured by GLC. The mRNA expressions of Δ6 and Δ5 desaturases were detected by real time quantitative RT-PCR. Sesamin and capsaicin had no effect on the mRNA expressions of Δ6 and Δ5 desaturases in rat hepatocytes. Capsaicin had no effect on both Δ6 and Δ5 desaturation indexes, either. On the other hand, sesamin significantly reduced the index of Δ5 desaturation but not Δ6 desaturation. These results suggested that sesamin reduced the Δ5 desaturation index without the changing of the Δ5 desaturase mRNA level.