Effects of glycyrrhizin on renal functions in association with the regulation of water channels.
It is well-known that the mineralocorticoid action of glycyrrhizin, which is the major component of Glycyrrhiza uralensis, is caused by a defect in the conversion of cortisol to cortisone by the inhibition of 11-beta-hydroxysteroid dehydrogenase enzyme activity. In the present study, we investigated the mechanisms of salt and water retention in the kidney of rats administered excess amounts of glycyrrhizin (200 mg/kg/day, p.o.). Up-regulation of aquaporin (AQP) 2 and 3 water channels was detected in the renal inner and outer medulla by Western blot analysis in rats treated with glycyrrhizin for 0.5, 1 and 2 consecutive weeks. Our results show that urine flow rates and sodium excretion rates in glycyrrhizin-treated rats were decreased significantly, but creatinine clearance (Ccr) was not altered. The decreases of urine volume and urinary sodium excretion in glycyrrhizin-treated rats were reversed by a 2-week injection of spironolactone, which is a well-known mineralocorticoid receptor (MR) blocker. These results suggest that the retention of water and salt in glycyrrhizin-treated rats is, at least in part, accounted for by the increased expression of AQP 2 and 3 in the kidney, which may be causally related to the MR.
Kang
Dae Gill
DG
Professional Graduate School of Oriental Medicine, and Medicinal Resources Research Center, Wonkwang University, Iksan, Chonbuk, 570-749, Korea.
Sohn
Eun Jin
EJ
Lee
Ho Sub
HS
D000818:Animals; D020346:Aquaporins / Q000187:drug effects* / Q000378:metabolism; D015153:Blotting, Western / Q000379:methods; D004305:Dose-Response Relationship, Drug; D019695:Glycyrrhizic Acid / Q000494:pharmacology*; D007671:Kidney Concentrating Ability / Q000187:drug effects*; D007672:Kidney Cortex / Q000187:drug effects* / Q000378:metabolism; D007679:Kidney Medulla / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D018161:Receptors, Mineralocorticoid / Q000378:metabolism*; D013997:Time Factors
D020346:Aquaporins; D018161:Receptors, Mineralocorticoid; D019695:Glycyrrhizic Acid