Guar gum consumption increases hepatic nuclear SREBP2 and LDL receptor expression in pigs fed an atherogenic diet

J Nutr. 2007 Mar;137(3):568-72. doi: 10.1093/jn/137.3.568.

Abstract

To gain insight into the regulation of hepatic sterol-responsive genes that are thought to mediate the hypocholesterolemic effects of guar gum (GG) consumption, the mRNA and protein expression of sterol regulatory element binding protein 2 (SREBP2), LDL receptor (LDLr), and scavenger receptor class B, type 1 (SR-B1) were examined in pigs consuming an atherogenic control diet or the control diet supplemented with 10% GG. Compared with the control group, GG consumption reduced (P < 0.05) plasma total cholesterol and LDL cholesterol concentrations by 27 and 37%, respectively. Furthermore, hepatic free cholesterol concentration was lower (P < 0.05) in the GG-fed pigs in comparison with the control group. GG consumption increased hepatic LDLr mRNA (1.5-fold of the control, P = 0.09) and protein (2-fold of the control, P < 0.05) expression in comparison with the control group. However, GG consumption reduced hepatic SR-B1 mRNA to 36% of the control (P < 0.05) expression but did not affect (P = 0.19) SR-B1 protein abundance in comparison with the control group. Although SREBP2 mRNA expression was similar (P = 0.89) in the 2 groups, GG consumption increased (P < 0.05) the expression of the cytoplasmic precursor (3-fold of the control) and nuclear active forms (1.5-fold of the control) of SREBP2. We conclude that the hypocholesterolemic effects of GG consumption are related to a reduction in hepatic free cholesterol concentration and associated increases in nuclear active SREBP2 expression and hepatic LDLr abundance.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anticholesteremic Agents / administration & dosage
  • Atherosclerosis / diet therapy
  • Atherosclerosis / genetics
  • Atherosclerosis / metabolism
  • Atherosclerosis / prevention & control
  • Base Sequence
  • DNA Primers / genetics
  • Diet, Atherogenic*
  • Dietary Fiber / administration & dosage
  • Galactans / administration & dosage
  • Liver / metabolism*
  • Mannans / administration & dosage
  • Plant Gums / administration & dosage
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Receptors, LDL / genetics*
  • Receptors, LDL / metabolism*
  • Sterol Regulatory Element Binding Protein 2 / genetics*
  • Sterol Regulatory Element Binding Protein 2 / metabolism*
  • Sus scrofa

Substances

  • Anticholesteremic Agents
  • DNA Primers
  • Dietary Fiber
  • Galactans
  • Mannans
  • Plant Gums
  • RNA, Messenger
  • Receptors, LDL
  • Sterol Regulatory Element Binding Protein 2
  • guar gum