Besides its role as a carboxylase prosthetic group, biotin regulates gene expression and has a wide repertoire of effects on systemic processes. Several studies have shown that pharmacological concentrations of biotin reduce hypertriglyceridemia. The molecular mechanisms by which pharmacological concentrations of biotin affect lipid metabolism are largely unknown. The present study analyzed the effects of pharmacological doses of biotin on triglyceridemia, insulin sensitivity and on mRNA expression of various lipogenic genes. Three-week-old male BALB/cAnN Hsd mice were fed a biotin-control or a biotin-supplemented diet (1.76 or 97.7mg of free biotin/kg diet, respectively) over a period of eight weeks. Serum triglyceride concentrations, insulin and glucose tolerance and mRNA abundance of various lipogenic genes were investigated. The biotin-supplemented group showed 35% less serum triglycerides than control mice. In the liver, we found a significant (P<0.05) reduction of mRNA levels of SREBP1-c, glucose transporter-2, phosphofructokinase-1, pyruvate kinase, acetyl-CoA carboxylase and fatty acid synthase, while glucose-6-phosphate dehydrogenase expression increased. No changes in glucokinase, stearoyl-CoA desaturase-1, FoxO1 or PPAR-gamma expression were observed. In adipose tissue, we found a decreased expression of SREBP1c, glucose-6-phosphate deshydrogenase, acetyl-CoA carboxylase, fatty acid synthase, stearoyl-CoA desaturase-1, phosphofructokinase-1 and PPAR-gamma, but no changes in FoxO1 expression. Moreover, the group fed a biotin-supplemented diet showed a significant decrease in adipose tissue weight. No differences in insulin sensitivity or serum insulin concentrations were observed between groups. Our results indicate that pharmacological concentrations of biotin decrease serum tryglyceride concentrations and lipogenic gene expression in liver and adipose tissues.
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