Lipoprotein Lipase Expression, Serum Triacylglycerol and Tissue Lipid Deposition in Rats Fed on Switching Type of Diet and Treated with Glycyrrhizic Acid

Aims: To determine the anti-hyperglycaemic and anti-hyperlipidaemic effects of glycyrrhizic acid (GA), the root extract of Glycyrrhiza glabra in rats with switching type of diet i.e. between normal diet (ND) and high-fat diet (HFD).

Study Design: In vivo study.

Place and Duration of Study: School of Science, Monash University Sunway Campus between January 2010 and October 2010.

Methodology: Sixteen Sparague-Dawley rats were divided into two groups having eight animals each i.e. group A- ND+GA→ HFD+GA; group B- ND+GA→HFD+no GA. Rats were fed with the corresponding diet and GA (100 mg/kg) for 28 days. The blood glucose, insulin and triacylglycerol levels, lipoprotein lipase expression in the liver, kidney, heart, abdominal muscle (AM), quadriceps femoris (QF), subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) and tissue lipid deposition were measured.

Results: No significant difference in blood glucose levels between groups. GA significantly lowered (P=.05) triacylglycerol in rats fed on a ND with GA and later switched to a HFD without GA (group B) compared to rats fed on a ND with GA and later switched to a HFD with continuous GA supplementation (group A). For LPL expression, group B had significant lower (P=.05) LPL expression in the liver, AM, kidney and heart than group A. Group A had significantly smaller (P=.05) size of VAT than group B.

Conclusion: These findings may indicate the role of GA in lowering blood glucose and triacylglycerol in subjects who had a switch from a ND with GA to a HFD without GA but not in those who had a switch from a ND with GA to a HFD with continuous GA supplementation.