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Glycyrrhizic acid improved lipoprotein lipase expression, insulin sensitivity, serum lipid and lipid deposition in high-fat diet-induced obese rats.

Eu CH, Lim WY, Ton SH, bin Abdul Kadir K - Lipids Health Dis (2010)

Bottom Line: With regard to lipid metabolism, GA administration led to significant hypotriglyceridemic and HDL-raising effects (p < 0.05), with a consistent reduction in serum free fatty acid, total cholesterol and LDL cholesterol and significant decrease in tissue lipid deposition across all studied tissue (p < 0.01).Such up-regulation was accompanied by a GA-mediated improvement in insulin sensitivity, which may be associated with a decrease in tissue lipid deposition.The HDL-raising effect of GA suggests the antiatherosclerotic properties of GA.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Science, Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway 46150, Selangor Darul Ehsan, Malaysia.

ABSTRACT

Background: The metabolic syndrome, known also as the insulin resistance syndrome, refers to the clustering of several risk factors for atherosclerotic cardiovascular disease. Dyslipidaemia is a hallmark of the syndrome and is associated with a whole body reduction in the activity of lipoprotein lipase (LPL), an enzyme under the regulation of the class of nuclear receptors known as peroxisome proliferator-activated receptor (PPAR). Glycyrrhizic acid (GA), a triterpenoid saponin, is the primary bioactive constituent of the roots of the shrub Glycyrrhiza glabra. Studies have indicated that triterpenoids could act as PPAR agonists and GA is therefore postulated to restore LPL expression in the insulin resistant state.

Results: Oral administration of 100 mg/kg of GA to high-fat diet-induced obese rats for 28 days led to significant reduction in blood glucose concentration and improvement in insulin sensitivity as indicated by the homeostasis model assessment of insulin resistance (HOMA-IR) (p < 0.05). LPL expression was up-regulated in the kidney, heart, quadriceps femoris, abdominal muscle and the visceral and subcutaneous adipose tissues but down-regulated in the liver--a condition in reverse to that seen in high-fat diet-induced obese rats without GA. With regard to lipid metabolism, GA administration led to significant hypotriglyceridemic and HDL-raising effects (p < 0.05), with a consistent reduction in serum free fatty acid, total cholesterol and LDL cholesterol and significant decrease in tissue lipid deposition across all studied tissue (p < 0.01).

Conclusion: In conclusion, GA may be a potential compound in improving dyslipidaemia by selectively inducing LPL expression in non-hepatic tissues. Such up-regulation was accompanied by a GA-mediated improvement in insulin sensitivity, which may be associated with a decrease in tissue lipid deposition. The HDL-raising effect of GA suggests the antiatherosclerotic properties of GA.

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Comparison of serum lipid. Mean concentration of total cholesterol, TAG, HDL-cholesterol, LDL-cholesterol and serum FFA in rats from groups A, B and C. ** indicates p < 0.01 and * indicates p < 0.05 when compared between groups. [Group A: rats fed on normal diet without GA; Group B: rats fed on high-fat diet without GA; Group C: rats fed on high-fat diet and given 100 mg/kg of GA].
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Figure 6: Comparison of serum lipid. Mean concentration of total cholesterol, TAG, HDL-cholesterol, LDL-cholesterol and serum FFA in rats from groups A, B and C. ** indicates p < 0.01 and * indicates p < 0.05 when compared between groups. [Group A: rats fed on normal diet without GA; Group B: rats fed on high-fat diet without GA; Group C: rats fed on high-fat diet and given 100 mg/kg of GA].

Mentions: Overall, rats from group C had improved lipid profile with a 6.80% decrease in total cholesterol, 22.33% decrease in TAG, 13.33% decrease in LDL, 12.21% increase in HDL and 7.32% decrease in serum FFA (Figure 6). Comparison of lipid profiles of rats from groups A, B and C showed that mean total cholesterol was the highest in rats from group B (2.94 ± 0.94 mmol/L) compared to groups A (2.60 ± 0.32 mmol/L) and C (2.74 ± 0.14 mmol/L). No significant difference was observed between all groups. TAG concentrations in groups A, B and C were 0.58 ± 0.02, 1.03 ± 0.07 and 0.80 ± 0.07 mmol/L respectively. A significant increase (77.59%) was observed in group B compared to A (p < 0.01) while a significant decrease (22.33%) was seen in group C compared to B (p < 0.05). HDL concentrations in groups A, B and C were 1.86 ± 0.16, 1.72 ± 0.05 and 1.93 ± 0.06 mmol/L respectively and this represented a significant increase (12.21%) in group C compared to B (p < 0.05). LDL concentrations showed no significant difference between all three groups which has a level of 0.55 ± 0.15 (group A), 0.75 ± 0.11 (group B) and 0.65 ± 0.12 (group C) mmol/L respectively. Lastly, FFA levels were 1.05 ± 0.04, 1.23 ± 0.16 and 1.14 ± 0.14 mmol/L respectively for groups A, B and C with no significant difference between any groups.


Glycyrrhizic acid improved lipoprotein lipase expression, insulin sensitivity, serum lipid and lipid deposition in high-fat diet-induced obese rats.

Eu CH, Lim WY, Ton SH, bin Abdul Kadir K - Lipids Health Dis (2010)

Comparison of serum lipid. Mean concentration of total cholesterol, TAG, HDL-cholesterol, LDL-cholesterol and serum FFA in rats from groups A, B and C. ** indicates p < 0.01 and * indicates p < 0.05 when compared between groups. [Group A: rats fed on normal diet without GA; Group B: rats fed on high-fat diet without GA; Group C: rats fed on high-fat diet and given 100 mg/kg of GA].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927592&req=5

Figure 6: Comparison of serum lipid. Mean concentration of total cholesterol, TAG, HDL-cholesterol, LDL-cholesterol and serum FFA in rats from groups A, B and C. ** indicates p < 0.01 and * indicates p < 0.05 when compared between groups. [Group A: rats fed on normal diet without GA; Group B: rats fed on high-fat diet without GA; Group C: rats fed on high-fat diet and given 100 mg/kg of GA].
Mentions: Overall, rats from group C had improved lipid profile with a 6.80% decrease in total cholesterol, 22.33% decrease in TAG, 13.33% decrease in LDL, 12.21% increase in HDL and 7.32% decrease in serum FFA (Figure 6). Comparison of lipid profiles of rats from groups A, B and C showed that mean total cholesterol was the highest in rats from group B (2.94 ± 0.94 mmol/L) compared to groups A (2.60 ± 0.32 mmol/L) and C (2.74 ± 0.14 mmol/L). No significant difference was observed between all groups. TAG concentrations in groups A, B and C were 0.58 ± 0.02, 1.03 ± 0.07 and 0.80 ± 0.07 mmol/L respectively. A significant increase (77.59%) was observed in group B compared to A (p < 0.01) while a significant decrease (22.33%) was seen in group C compared to B (p < 0.05). HDL concentrations in groups A, B and C were 1.86 ± 0.16, 1.72 ± 0.05 and 1.93 ± 0.06 mmol/L respectively and this represented a significant increase (12.21%) in group C compared to B (p < 0.05). LDL concentrations showed no significant difference between all three groups which has a level of 0.55 ± 0.15 (group A), 0.75 ± 0.11 (group B) and 0.65 ± 0.12 (group C) mmol/L respectively. Lastly, FFA levels were 1.05 ± 0.04, 1.23 ± 0.16 and 1.14 ± 0.14 mmol/L respectively for groups A, B and C with no significant difference between any groups.

Bottom Line: With regard to lipid metabolism, GA administration led to significant hypotriglyceridemic and HDL-raising effects (p < 0.05), with a consistent reduction in serum free fatty acid, total cholesterol and LDL cholesterol and significant decrease in tissue lipid deposition across all studied tissue (p < 0.01).Such up-regulation was accompanied by a GA-mediated improvement in insulin sensitivity, which may be associated with a decrease in tissue lipid deposition.The HDL-raising effect of GA suggests the antiatherosclerotic properties of GA.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Science, Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway 46150, Selangor Darul Ehsan, Malaysia.

ABSTRACT

Background: The metabolic syndrome, known also as the insulin resistance syndrome, refers to the clustering of several risk factors for atherosclerotic cardiovascular disease. Dyslipidaemia is a hallmark of the syndrome and is associated with a whole body reduction in the activity of lipoprotein lipase (LPL), an enzyme under the regulation of the class of nuclear receptors known as peroxisome proliferator-activated receptor (PPAR). Glycyrrhizic acid (GA), a triterpenoid saponin, is the primary bioactive constituent of the roots of the shrub Glycyrrhiza glabra. Studies have indicated that triterpenoids could act as PPAR agonists and GA is therefore postulated to restore LPL expression in the insulin resistant state.

Results: Oral administration of 100 mg/kg of GA to high-fat diet-induced obese rats for 28 days led to significant reduction in blood glucose concentration and improvement in insulin sensitivity as indicated by the homeostasis model assessment of insulin resistance (HOMA-IR) (p < 0.05). LPL expression was up-regulated in the kidney, heart, quadriceps femoris, abdominal muscle and the visceral and subcutaneous adipose tissues but down-regulated in the liver--a condition in reverse to that seen in high-fat diet-induced obese rats without GA. With regard to lipid metabolism, GA administration led to significant hypotriglyceridemic and HDL-raising effects (p < 0.05), with a consistent reduction in serum free fatty acid, total cholesterol and LDL cholesterol and significant decrease in tissue lipid deposition across all studied tissue (p < 0.01).

Conclusion: In conclusion, GA may be a potential compound in improving dyslipidaemia by selectively inducing LPL expression in non-hepatic tissues. Such up-regulation was accompanied by a GA-mediated improvement in insulin sensitivity, which may be associated with a decrease in tissue lipid deposition. The HDL-raising effect of GA suggests the antiatherosclerotic properties of GA.

Show MeSH
Related in: MedlinePlus