Modulation of glucose and lipid metabolism in adrenalectomised rats given glycyrrhizic acid

Abstract

Yan Qi Ng, Chanchal Chandramouli, So Ha Ton, Khalid Abdul Kadir, Fahreen Haque, Melissa Sharmini Tamotharan

Background: Glycyrrhizic acid (GA) was found to improve blood glucose and dyslipidaemia with increased lipoprotein lipase (LPL) expression and reduction in 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1), hexose-6-phosphate dehydrogenase (H6PDH), phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) activities in liver, kidney, skeletal muscles and adipose tissues. However, it was not known if these were a direct action from GA or indirect involving glucocorticoids (GC). Methods: Adrenalectomised (ADX) rats were used to investigate the effects of GA administration on glucose and lipid metabolism in the absence of endogenous GC. Thirty male Sparague Dawley rats were randomly assigned to three groups of ten; designated the sham, ADX and GA-administered (100mg/kg; orally) ADX groups. After 28 days of treatment, the blood samples collected were analysed for glucose, serum insulin and lipid profiles. Tissues collected were analysed for LPL expression and 11β-HSD1, H6PDH, PEPCK and G6 Pase activities. Result: Improvement in blood glucose level was seen in ADX compared to the sham rats (33%; p0.05). Adrenalectomy also led to significant reduction in PEPCK (p0.05) and H6PDH (p0.05). Improvement in cholesterol levels (p<0.05) was seen in GA-administered ADX rats with increase liver LPL expression (p<0.05). Conclusion: Reduction of hepatic and renal PEPCK, G6Pase and H6PDH activities by GA could be due to inhibition of 11β-HSD1 involving GC. However, increased PEPCK activities in adipose tissues, reduction in H6PDH activities in all the aforementioned tissues and improvement of LPL expression appeared to be independent of GC..