Glycyrrhizin induces mineralocorticoid activity through alterations in cortisol metabolism in the human kidney

Argon Attenuates Multiorgan Failure in Relation with HMGB1 Inhibition

Argon inhalation attenuates multiorgan failure (MOF) after experimental ischemic injury. We hypothesized that this protection could involve decreased High Mobility Group Box 1 (HMGB1) systemic release. We investigated this issue in an animal model of MOF induced by aortic cross-clamping. Anesthetized rabbits were submitted to supra-coeliac aortic cross-clamping for 30 min, followed by 300 min of reperfusion. They were randomly divided into three groups (n = 7/group). The Control group inhaled nitrogen (70%) and oxygen (30%). The Argon group was exposed to a mixture of argon (70%) and oxygen (30%). The last group inhaled nitrogen/oxygen (70/30%) with an administration of the HMGB1 inhibitor glycyrrhizin (4 mg/kg i.v.) 5 min before aortic unclamping. At the end of follow-up, cardiac output was significantly higher in Argon and Glycyrrhizin vs. Control (60 ± 4 and 49 ± 4 vs. 33 ± 8 mL/kg/min, respectively). Metabolic acidosis was attenuated in Argon and Glycyrrhizin vs. Control, along with reduced amount of norepinephrine to reverse arterial hypotension. This was associated with reduced interleukin-6 and HMGB1 plasma concentration in Argon and Glycyrrhizin vs. Control. End-organ damages were also attenuated in the liver and kidney in Argon and Glycyrrhizin vs. Control, respectively. Argon inhalation reduced HMGB1 blood level after experimental aortic cross-clamping and provided similar benefits to direct HMGB1 inhibition.

Geriatric Patients Are at a High Risk of Hypokalemia Associated with Yokukansan Preparation: A Retrospective Cohort Study

Although hypokalemia is an adverse effect of Yokukansan preparation, especially in geriatric patients, its association with age is unclear. We investigated whether age is a risk factor for hypokalemia. This single-center retrospective cohort study, conducted at Tokyo Women's Medical University, Medical Center East between June 2015 and May 2019, included patients who received the Yokukansan preparation. The primary outcome was hypokalemia (serum potassium level: < 3.0 mEq/L). A multivariate Cox proportional hazard model was used to determine risk factors, hazard ratio (HR) and 95% confidence interval (95% CI). The cut-off age was also examined. Of 665 patients (median age: 78 years; interquartile range: 68-84 years), 55 (8.3%) developed hypokalemia associated with Yokukansan preparation. Risk factors for hypokalemia were age (HR: 1.013, 95% CI: 1.006-1.021, p < 0.001), dementia (HR: 0.500, 95% CI: 0.357-0.682, p < 0.001), serum albumin level (HR: 0.754, 95% CI: 0.669-0.850, p < 0.001), and daily Yokukansan preparation dose ≥ 7.5 g (HR: 1.446, 95% CI: 1.144-1.850, p = 0.002). The cut-off ages were >75 and >80 years but not 65 years and >70 years. Clinicians should assess risk factors and monitor serum potassium levels to avoid hypokalemia associated with the Yokukansan preparation.

Inhibition of thymic stromal lymphopoietin production to improve pruritus and quality of life in infants and children with atopic dermatitis

Background

Atopic dermatitis (AD) is an inflammatory pruritic chronic dermatosis involving the alarmin thymic stromal lymphopoietin (TSLP), which is directly implicated in AD pruritus.

Aims

To evaluate the efficacy of Tambourissa trichophylla leaf extract (TTLE) titrated in polyphenols and 18β‐glycyrrhetinic acid (GA) in vitro and in vivo for AD pruritus.

Patients/Methods

Initially, in vitro assessment of TSLP production in keratinocytes was undertaken. In normal human keratinocytes in vitro, TSLP was induced by polyinosinic:polycytidylic acid (Poly:IC), tumor necrosis factor (TNF)‐α, and interleukin (IL)‐4 and then quantified by ELISA in supernatants. Some cells were pretreated with TTLE and/or GA. Thereafter, an in vivo clinical study was performed including 48 infants and children with mild to severe AD flare‐ups, some of which were treated with topical corticosteroids. A topical spray containing TTLE and GA was applied. After 21 days of topical spray application, pruritus, sleeplessness, the SCORing Atopic Dermatitis (SCORAD) index, the Infant's Dermatitis Quality of Life index (IDQOL), and the Dermatitis Family Impact Questionnaire (DFIQ) were assessed.

Results

Thymic stromal lymphopoietin secretion was inhibited significantly in an AD environment by TTLE and GA by up to 57.2% and 73.3%, respectively. The use of the topical spray induced a significant reduction in pruritus and sleeplessness scores, as well as the SCORAD, IDQOL, and DFIQ indexes in the total group. Similar results were observed in patient subgroups with or without topical corticosteroid treatment.

Conclusions

A topical spray containing TTLE and GA, which inhibit TSLP secretion, efficiently decreases AD pruritus and improves the quality of life of AD patients.

Bioactive Candy: Effects of Licorice on the Cardiovascular System

Licorice, today chiefly utilized as a flavoring additive in tea, tobacco and candy, is one of the oldest used herbs for medicinal purposes and consists of up to 300 active compounds. The main active constituent of licorice is the prodrug glycyrrhizin, which is successively converted to 3β-monoglucuronyl-18β-glycyrrhetinic acid (3MGA) and 18β-glycyrrhetinic acid (GA) in the intestines. Despite many reported health benefits, 3MGA and GA inhibit the 11-β-hydrogenase type II enzyme (11β-HSD2) oxidizing cortisol to cortisone. Through activation of mineralocorticoid receptors, high cortisol levels induce a mild form of apparent mineralocorticoid excess in the kidney and increase systemic vascular resistance. Continuous inhibition of 11β-HSD2 related to excess licorice consumption will create a state of hypernatremia, hypokalemia and increased fluid volume, which can cause serious life-threatening complications especially in patients already suffering from cardiovascular diseases. Two recent meta-analyses of 18 and 26 studies investigating the correlation between licorice intake and blood pressure revealed statistically significant increases both in systolic (5.45 mmHg) and in diastolic blood pressure (3.19/1.74 mmHg). This review summarizes and evaluates current literature about the acute and chronic effects of licorice ingestion on the cardiovascular system with special focus on blood pressure. Starting from the molecular actions of licorice (metabolites) inside the cells, it describes how licorice intake is affecting the human body and shows the boundaries between the health benefits of licorice and possible harmful effects.

Saponins as modulators of nuclear receptors

As plant-derived natural products, saponins have been widely applied for the dietary modification of metabolic syndrome. However, the underlying mechanisms of their preventive and therapeutic effects are still largely unclear. Nuclear receptors have been identified as potential pharmaceutical targets for treating various types of metabolic disorders. With similar structure to endogenous hormones, several saponins may serve as selective ligands for nuclear receptors. Recently, a series of saponins are proved to exert their physiological activities through binding to nuclear receptors. This review summarizes the biological and pharmacological activities of typical saponins mediated by some of the most well described nuclear receptors, including the classical steroid hormone receptors (ER, GR, MR, and AR) and the adopted orphan receptors (PPAR, LXR, FXR, and PXR).

Development of cleaved amplified polymorphic sequence (CAPS) and high-resolution melting (HRM) markers from the chloroplast genome of Glycyrrhiza species

Licorice (Glycyrrhiza glabra) is an important medicinal crop often used as health foods or medicine worldwide. The molecular genetics of licorice is under scarce owing to lack of molecular markers. Here, we have developed cleaved amplified polymorphic sequence (CAPS) and high-resolution melting (HRM) markers based on single nucleotide polymorphisms (SNP) by comparing the chloroplast genomes of two Glycyrrhiza species (G. glabra and G. lepidota). The CAPS and HRM markers were tested for diversity analysis with 24 Glycyrrhiza accessions. The restriction profiles generated with CAPS markers classified the accessions (2-4 genotypes) and melting curves (2-3) were obtained from the HRM markers. The number of alleles and major allele frequency were 2-6 and 0.31-0.92, respectively. The genetic distance and polymorphism information content values were 0.16-0.76 and 0.15-0.72, respectively. The phylogenetic relationships among the 24 accessions were estimated using a dendrogram, which classified them into four clades. Except clade III, the remaining three clades included the same species, confirming interspecies genetic correlation. These 18 CAPS and HRM markers might be helpful for genetic diversity assessment and rapid identification of licorice species.

The association between consistent licorice ingestion, hypertension and hypokalaemia: a systematic review and meta-analysis

There have been numerous case reports of severe adverse events including deaths following chronic licorice ingestion. The aim of the present study was to evaluate the effect of chronic ingestion of licorice on blood pressure, plasma potassium, plasma renin activity and plasma aldosterone. A search of MEDLINE, PubMed, EMBASE, CENTRAL, DARE, CINAHL and Current Contents Connect was performed from inception through to 26 April 2017. Trials that included a treatment group ingesting a product containing at least 100 mg of glycyrrhizic acid daily were selected. Pooled mean changes from baseline with 95% confidence intervals were calculated for diastolic blood pressure, systolic blood pressure, plasma potassium, plasma renin activity and plasma aldosterone using a random effects model. An assessment of dose-response was also undertaken. A total of 18 studies (n=337) were included in the meta-analysis. There was a statistically significant increase in mean systolic blood pressure (5.45 mm Hg, 95% CI 3.51-7.39) and diastolic blood pressure (3.19 mm Hg, 95% CI 0.10-6.29) after chronic ingestion of a product containing glycyrrhizic acid. Plasma potassium (-0.33 mmol l-1, 95% CI -0.42 to 0.23), plasma renin activity (-0.82 ngml-1 per hour, 95% CI -1.27 to -0.37) and plasma aldosterone (-173.24 pmol l-1, 95% CI -231.65 to -114.83) were all significantly decreased. A significant correlation was noted between daily dose of glycyrrhizic acid and systolic blood pressure (r2=0.55) and diastolic blood pressure (r2=0.65), but not for the other outcome measures. Hence, chronic licorice ingestion is associated with an increase in blood pressure and a drop in plasma potassium, even at modest doses. This is of particular relevance for individuals with existing cardiovascular disease.

Comparison of glycyrrhizin content in 25 major kinds of Kampo extracts containing Glycyrrhizae Radix used clinically in Japan

Glycyrrhizae Radix is the most frequently used crude drug in Japan and is prescribed in Kampo medicine for the treatment of a wide range of diseases. The major active ingredient of Glycyrrhizae Radix, glycyrrhizin (GL), has been shown to possess various pharmacological actions, but is also known to cause adverse effects such as pseudoaldosteronism. To avoid the adverse effects of GL, precautions have been indicated on the package inserts of Glycyrrhizae Radix-containing formulas depending on the amount of Glycyrrhizae Radix they contain. However, it remains unknown whether the extraction efficiency of GL from Glycyrrhizae Radix is constant throughout the different combinations of crude drugs in Glycyrrhizae Radix-containing formulas. To confirm the basis of the safety regulation, in this study we comprehensively determined the GL content of 25 major kinds of Kampo extracts compounding Glycyrrhizae Radix. We found that the GL content per daily dosage in all Kampo extracts are generally proportional to the compounding amount of Glycyrrhizae Radix, except in the case of shoseiryuto (Sho-seiryu-To). We also found that Schisandrae Fructus in Sho-seiryu-To decoction caused a lowered pH condition and drastically decreased the extraction efficacy of GL from Glycyrrhizae Radix. Moreover, we were able to confirm that the extraction efficiency of GL from Glycyrrhizae Radix is dependent on the pH value of the extraction solvent. The extraction efficiency of GL in the 25 kinds of Kampo extracts was not constant but it correlates significantly with the pH value of the decoction. Furthermore, the GL contents are well correlated with pseudoaldosteronism incidence data obtained from the Japanese Adverse Drug Event Report (JADER) database on the 25 kinds of Kampo extracts. This suggests that the GL content is a better index to consider to avoid the adverse effects of Glycyrrhizae Radix-containing Kampo formulas.

11-Beta Dehydrogenase Type 2 Activity Is Not Reduced in Treatment Resistant Hypertension

BACKGROUND AND OBJECTIVE

Decreased renal 11-beta dehydrogenase type 2 (11β-HSD2) activity, as reflected by an increased urinary free cortisol to cortisone ratio (UFF/UFE), is associated with having hypertension (HTN). The current study was conducted to determine if reduced 11β-HSD2 activity is also associated with having resistant HTN.

METHOD

We evaluated 55 consecutive patients with RHTN, defined as blood pressure (BP) ≥140/90 mm Hg despite using ≥3 antihypertensive medications including a diuretic, and 38 patients whose BP was controlled on ≤3 medications to serve as a non-RHTN comparator group. All patients underwent biochemical evaluation, including measurement of 24-hour urinary UFF/UFE.

RESULTS

The 2 study groups had similar demographic characteristics. Systolic, diastolic BP, and number of antihypertensive medications were greater in patients with uncontrolled RHTN vs. the control group (167.5 ± 28.2/91.2 ± 18.8 vs. 126.6 ± 11.4/77.8 ± 8.65 mm Hg and 4.31 ± 1.23 vs. 2.74 ± 0.6, respectively). The 24-hour UFF was 13.6 ± 11.8 vs. 14.3 ± 10.7 µg/24 h and UFE was 64.9 ± 36.3 vs. 76.1 ± 44 µg/24 h such that the UFF/UFE was 0.22 ± 0.16 vs. 0.19 ± 0.09 in RHTN vs. the control group. This ratio was not associated to age, race, gender, and body mass index.

CONCLUSION

An elevated UFF/UFE was not present in this large cohort of patients with uncontrolled RHTN. This suggests that reduced conversion of cortisol to cortisone does not contribute to the development of RHTN.

Hepatic 11 beta-hydroxysteroid dehydrogenase 1 involvement in alterations of glucose metabolism produced by acidotic stress in rat

11 beta-hydroxysteroid dehydrogenase (HSDs) enzymes regulate the activity of glucocorticoids in target organs. HSD1, one of the two existing isoforms, locates mainly in CNS, liver and adipose tissue. HSD1 is involved in the pathogenesis of diseases such as obesity, insulin resistance, arterial hypertension and the Metabolic Syndrome. The stress produced by HCl overload triggers metabolic acidosis and increases liver HSD1 activity associated with increased phosphoenolpyruvate carboxykinase, a regulatory enzyme of gluconeogenesis that is activated by glucocorticoids, with increased glycaemia and glycogen breakdown. The aim of this study was to analyze whether the metabolic modifications triggered by HCl stress are due to increased liver HSD1 activity. Glycyrrhetinic acid, a potent HDS inhibitor, was administered subcutaneously (20 mg/ml) to stressed and unstressed four months old maleSprague Dawley rats to investigate changes in liver HSD1, phosphoenolpyruvate carboxykinase (PECPK) and glycogen phosphorylase activities and plasma glucose levels. It was observed that all these parameters increased in stressed animals, but that treatment with glycyrrhetinic acid significantly reduced their levels. In conclusion, our results demonstrate the involvement of HSD1 in stress induced carbohydrate disturbances and could contribute to the impact of HSD1 inhibitors on carbohydrate metabolism and its relevance in the study of Metabolic Syndrome Disorder and non insulin-dependent diabetes mellitus.

11β-Hydroxysteroid dehydrogenase type-2 and type-1 (11β-HSD2 and 11β-HSD1) and 5β-reductase activities in the pathogenia of essential hypertension

Cortisol availability is modulated by several enzymes: 11β-HSD2, which transforms cortisol (F) to cortisone (E) and 11β-HSD1 which predominantly converts inactive E to active F. Additionally, the A-ring reductases (5α- and 5β-reductase) inactivate cortisol (together with 3α-HSD) to tetrahydrometabolites: 5αTHF, 5βTHF, and THE. The aim was to assess 11β-HSD2, 11β-HSD1, and 5β-reductase activity in hypertensive patients. Free urinary F, E, THF, and THE were measured by HPLC-MS/MS in 102 essential hypertensive patients and 18 normotensive controls. 11β-HSD2 enzyme activity was estimated by the F/E ratio, the activity of 11β-HSD1 in compare to 11β-HSD2 was inferred by the (5αTHF + 5βTHF)/THE ratio and 5β-reductase activity assessed using the E/THE ratio. Activity was considered altered when respective ratios exceeded the maximum value observed in the normotensive controls. A 15.7% of patients presented high F/E ratio suggesting a deficit of 11β-HSD2 activity. Of the remaining 86 hypertensive patients, two possessed high (5αTHF + 5βTHF)/THE ratios and 12.8% had high E/THE ratios. We observed a high percentage of alterations in cortisol metabolism at pre-receptor level in hypertensive patients, previously misclassified as essential. 11β-HSD2 and 5β-reductase decreased activity and imbalance of 11β-HSDs should be considered in the future management of hypertensive patients.

A hypokalemic muscular weakness after licorice ingestion: a case report

A 21-year-old male presented to the emergency department with the complaint of muscle weakness. The patient had used a powderized over-the-counter product named 'Tekumut' for 2 weeks to quit smoking. The granulated product was studied and determined to contain 'licorice' containing glycyrrhizic acid.

Licorice (a plant which contain glycyrrhizic acid) -induced hypokalemia usually has a mild progression. However, it may cause a critical failure in physical action by means of weakness followed by paralysis and may cause rhabdomyolysis or ventricular fibrillation, leading to death, when left untreated.

This report has presented the first case with hypocalemia due to licorice consumption in granulated form from Turkey. In addition, the report has aimed to emphasize the importance of obtaining the detailed history of a patient in diagnosis.

Inactivation of glucocorticoids by 11beta-hydroxysteroid dehydrogenase enzymes increases during the meiotic maturation of porcine oocytes

Recent reports have shown that glucocorticoids can modulate oocyte maturation in both teleost fish and mammals. Within potential target cells, the actions of physiological glucocorticoids are modulated by 11beta-hydroxysteroid dehydrogenase (HSD11B) isoenzymes that catalyse the interconversion of cortisol and cortisone. Hence, the objective of this study was to establish whether HSD11B enzymes mediate cortisol-cortisone metabolism in porcine oocytes and, if so, whether the rate of glucocorticoid metabolism changes during oocyte maturation. Enzyme activities were measured in cumulus-oocyte complexes (COCs) and denuded oocytes (DOs) using radiometric conversion assays. While COCs and DOs oxidised cortisol to inert cortisone, there was no detectable regeneration of cortisol from cortisone. The rate of cortisol oxidation was higher in expanded COCs than in compact COCs containing germinal vesicle (GV) stage oocytes (111+/-6 vs 2041+/-115 fmol cortisone/oocyte.24 h; P<0.001). Likewise, HSD11B activities were 17+/-1 fold higher in DOs from expanded COCs than in those from compact COCs (P<0.001). When GV stage oocytes were subject to a 48 h in vitro maturation protocol, the enzyme activities were significantly increased from 146+/-18 to 1857+/-276 fmol cortisone/oocyte.24 h in GV versus MII stage oocytes respectively (P<0.001). Cortisol metabolism was inhibited by established pharmacological inhibitors of HSD11B (glycyrrhetinic acid and carbenoxolone), and by porcine follicular and ovarian cyst fluid. We conclude that an HSD11B enzyme (or enzymes) functions within porcine oocytes to oxidise cortisol, and that this enzymatic inactivation of cortisol increases during oocyte maturation.

Perturbed nuclear receptor signaling by environmental obesogens as emerging factors in the obesity crisis

The modern world is plagued with expanding epidemics of diseases related to metabolic dysfunction. The factors that are driving obesity, diabetes, cardiovascular disease, hypertension, and dyslipidemias (collectively termed metabolic syndrome) are usually ascribed to a mismatch between the body's homeostatic nutrient requirements and dietary excess, coupled with insufficient exercise. The environmental obesogen hypothesis proposes that exposure to a toxic chemical burden is superimposed on these conditions to initiate or exacerbate the development of obesity and its associated health consequences. Recent studies have proposed a first set of candidate obesogens (diethylstilbestrol, bisphenol A, phthalates and organotins among others) that target nuclear hormone receptor signaling pathways (sex steroid, RXR-PPARgamma and GR) with relevance to adipocyte biology and the developmental origins of health and disease (DOHaD). Perturbed nuclear receptor signaling can alter adipocyte proliferation, differentiation or modulate systemic homeostatic controls, leading to long-term consequences that may be magnified if disruption occurs during sensitive periods during fetal or early childhood development.

Hepatic stellate cell-targeted delivery of M6P-HSA-glycyrrhetinic acid attenuates hepatic fibrogenesis in a bile duct ligation rat model

BACKGROUND/AIMS

Hepatic stellate cells (HSCs) play a key role in fibrogenesis. Here, we used mannose-6-phosphate-modified human serum albumin (M6P(26)-HSA) as a selective carrier to deliver antifibrotic drug 18beta-glycyrrhetinic acid (18beta-GA) in experimental fibrosis animals, and tested its effect in injured liver tissues.

METHODS

Bile duct ligation (BDL) was performed to induce liver damage in rats. Masson's stain and immunocytochemistry were used to assess hepatic collagen deposits and uptakes of M6P(26)-HSA-GA in HSCs in rat livers. Gene expression profiles of procollagen type I alpha2, smooth muscle actin (SMA), and transforming growth factor-beta1 (TGF-beta1) were analysed by TaqMan and quantitative polymerase chain reaction assays. The depositions of M6P(26)-HSA-GA in the HSC-T6 cell line and primary HSCs were assessed by immunofluorescent staining.

RESULTS

Treatment with M6P(26)-HSA-GA at 10 mg/kg (three times/week for 2 weeks), but not the equivalent doses of free 18beta-GA and M6P(26)-HSA carrier alone, could significantly attenuate collagen deposits in BDL rat liver. Masson's stain and TaqMan assay revealed significant modulation of procollagen type I alpha2 in the BDL-injured liver. The depositions of M6P(26)-HSA-GA in HSCs were revealed by immunostaining with HSA and SMA markers. M6P(26)-HSA bound activated HSCs in vitro and the immunoreactivity of M6P(26)-HSA-GA was detected in the cytoplasm and cell surface of HSCs and HSC-T6 cells. The gene transcript levels of SMA and TGF-beta1 were modulated in HSC-T6 cells treated with M6P(26)-HSA-GA.

CONCLUSIONS

The M6P(26)-HSA holds promise as a targeting carrier for the liver or HSCs, which may be used to deliver 18beta-GA as a therapeutic agent to treat liver fibrosis.

Severe hypokalemia, rhabdomyolysis, muscle paralysis, and respiratory impairment in a hypertensive patient taking herbal medicines containing licorice

A 93 year-old hypertensive woman was found to have severe hypokalemia (as low as 1.3 mEq/L) and developed paralysis of the all extremities associated with metabolic alkalosis, hypoxemia, hypercapnea, extremely high levels of creatine phosphokinase (up to 9280 U/L), myoglobin and myoglobinuria compatible with rhabdomyolysis. Plasma renin activity and aldosterone levels were below normal. She was found to have been taking licorice-containing herbal medicines for the last 7 years. With the discontinuation of the licorice-containing medicines and administration of spironolactone together with intravenous and oral potassium supplement, her serum potassium level was normalized and her clinical symptoms and hypertension improved within 2 weeks.

Disruption of glucocorticoid action by environmental chemicals: potential mechanisms and relevance

Glucocorticoids play an essential role in the regulation of key physiological processes, including immunomodulation, brain function, energy metabolism, electrolyte balance and blood pressure. Exposure to naturally occurring compounds or industrial chemicals that impair glucocorticoid action may contribute to the increasing incidence of cognitive deficits, immune disorders and metabolic diseases. Potentially, "glucocorticoid disruptors" can interfere with various steps of hormone action, e.g. hormone synthesis, binding to plasma proteins, delivery to target cells, pre-receptor regulation of the ratio of active versus inactive hormones, glucocorticoid receptor (GR) function, or export and degradation of glucocorticoids. Several recent studies indicate that such chemicals exist and that some of them can cause multiple toxic effects by interfering with different steps of hormone action. For example, increasing evidence suggests that organotins disturb glucocorticoid action by altering the function of factors that regulate the expression of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) pre-receptor enzymes, by direct inhibition of 11beta-HSD2-dependent inactivation of glucocorticoids, and by blocking GR activation. These observations emphasize on the complexity of the toxic effects caused by such compounds and on the need of suitable test systems to assess their effects on each relevant step.

Cortisol metabolism in hypertension

Corticosteroids are critically involved in blood pressure regulation. Lack of adrenal steroids in Addison's disease causes life-threatening hypotension, whereas glucocorticoid excess in Cushing's syndrome invariably results in high blood pressure. At a pre-receptor level, glucocorticoid action is modulated by 11beta-hydroxysteroid dehydrogenases (11beta-HSDs). 11Beta-HSD1 activates cortisone to cortisol to facilitate glucocorticoid receptor (GR)-mediated action. By contrast, 11beta-HSD2 plays a pivotal role in aldosterone target tissues where it catalyses the opposite reaction (i.e. inactivation of cortisol to cortisone) to prevent activation of the mineralocorticoid receptor (MR) by cortisol. Mutations in the 11beta-HSD2 gene cause a rare form of inherited hypertension, the syndrome of apparent mineralocorticoid excess (AME), in which cortisol activates the MR resulting in severe hypertension and hypokalemia. Ingestion of competitive inhibitors of 11beta-HSD2 such as liquorice and carbenoxolone result in a similar but milder clinical phenotype. Epidemiological data suggests that polymorphic variability in the HSD11B2 gene determines salt sensitivity in the general population, which is a key predisposing factor to adult onset hypertension in some patients. Extrarenal sites of glucocorticoid action and metabolism that might impact on blood pressure include the vasculature and the central nervous system. Intriguingly, increased exposure to glucocorticoids during fetal life promotes high blood pressure in adulthood suggesting an early programming effect. Thus, metabolism and action in many peripheral tissues might contribute to the pathophysiology of human hypertension.

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.

Glycyrrhizic acid suppresses type 2 11 beta-hydroxysteroid dehydrogenase expression in vivo

Licorice-derivatives such as glycyrrhizic acid (GA) competitively inhibit 11 beta-hydroxysteroid dehydrogenase(11 beta-HSD) type 2 (11-HSD2) enzymatic activity, and chronic clinical use often results in pseudoaldosteronism. Since the effect of GA on 11-HSD2 expression remains unknown, we undertook in vivo and in vitro studies. Male Wistar rats were given 30, 60 or 120 mg/kg of GA twice a day for 2 weeks. Plasma corticosterone was decreased in those given the 120 mg dose, while urinary corticosterone excretion was increased in those given the 30 and 60 mg doses but decreased in those given 120 mg GA. NAD(+)-dependent dehydrogenase activity in kidney microsomal fraction was decreased in animals receiving doses of 60 and 120 mg GA. The 11-HSD2 protein and mRNA levels were decreased in those given 120 mg GA. In contrast, in vitro studies using mouse kidney M1 cells revealed that 24h treatment with glycyrrhetinic acid did not affect the 11-HSD2 mRNA expression levels. Thus, in addition to its role as a competitive inhibitor of 11-HSD2, the chronic high dose of GA suppresses mRNA and protein expression of 11-HSD2 possibly via indirect mechanisms. These effects may explain the prolonged symptoms after cessation of GA administration in some pseudoaldosteronism patients.

11Beta-hydroxysteroid-dehydrogenase isoforms: tissue distribution and implications for clinical medicine

11Beta-hydroxylation is essential for glucocorticoid and mineralocorticoid activity of a steroid. The enzyme catalyzing this reaction is termed 11beta-hydroxysteroid-dehydrogenase (11beta-HSD). Two isoenzymes of 11beta-HSD have been characterized in human tissues. Whereas 11beta-HSD-I works mainly as a reductase, 11beta-HSD-II only functions as an oxidizing (inactivating) enzyme for physiological glucocorticoids. Thus, the tissue distribution of both enzymes plays a crucial role for the specific glucocorticoid status of an organ. This review summarizes our knowledge of tissue distribution of both 11beta-HSD isoenzymes, their physiological function and pathophysiological role in certain clinical abnormalities, and their relevance to the metabolism of synthetic glucocorticoid and mineralocorticoid compounds.

Activity of renal 11betahydroxysteroid dehydrogenase 2 (11betaHSD2) in stressed animals

The enzyme 11betaHSD2 protects the non-selective mineralocorticoid receptor from occupation by glucocorticoids in aldosterone target tissues. We studied the effect of stress elicited by intubation with a rubber catheter and administration of 10 ml of 0.45% NaCl (G3), of 10 ml of 200 mM HCl (G4) or intubation alone (G2) on the kinetics of the renal enzyme compared with untreated rats (G1). Microsomes were incubated with increasing masses of 3H corticosterone and 400 microM NAD at pH=7.4 during 5 minutes. Samples were extracted with ethyl acetate and analyzed by TLC. Results for n=4: Vmax for G1, 4.82 +/- 0.67. G2, 10.04 +/- 0.16***. G3, 9.16 +/- 0.74**. G4, 10.19 +/- 0.79*** pmoles/min/mg prot. Km for G1, 22.37 +/- 2.42. G2, 50.72 +/- 7.05*. G3, 55.25 +/- 8.37**. G4, 27.40 +/- 3.20 nM. (***p<0.001, **p<0.01 and *p<0.05 vs G1). All treatments increased Vmax. Intubation alone and gavage with 0.45% NaCl, but not with 200 mM HCl, increased Km. Taking together, the results could reflect a way to prevent occupation of type I receptors by increased levels of circulating glucocorticoids due to stressful situations. This protection seems more efficient under acidotic conditions causing--in addition to an increased Vmax--a low Km for the enzyme.

Review article: glycyrrhizin as a potential treatment for chronic hepatitis C

Chronic hepatitis C is a slowly progressive liver disease that may evolve into cirrhosis with its potential complications of liver failure or hepatocellular carcinoma. Current therapy with alpha-interferon is directed at viral clearance, but sustained response is only achieved in 20-40% of patients without cirrhosis, and less than 20% in patients with cirrhosis who have the greatest need for therapy. Treatment for those who do not respond to anti-viral therapy is highly desirable. In Japan glycyrrhizin has been used for more than 20 years as treatment for chronic hepatitis. In randomized controlled trials, glycyrrhizin induced a significant reduction of serum aminotransferases and an improvement in liver histology compared to placebo. Recently, these short-term effects have been amplified by a well-conducted retrospective study suggesting that long-term usage of glycyrrhizin prevents development of hepatocellular carcinoma in chronic hepatitis C. The mechanism by which glycyrrhizin improves liver biochemistry and histology are undefined. Metabolism, pharmacokinetics, side-effects, and anti-viral and hepatoprotective effects of glycyrrhizin are discussed.

Apparent mineralocorticoid excess syndromes

Apparent mineralocorticoid excess (AME) is a syndrome attributable to congenital deficiency of the enzyme 11 beta-dehydrogenase (11 beta-OHSD) which converts active glucocorticoid cortisol to inactive cortisone. When 11 beta-OHSD activity is impaired, cortisol acts as a potent mineralocorticoid and causes hypertension and hypokalemia with a suppression of the renin-angiotensin-aldosterone system. The increased ratio of urinary cortisol/cortisone metabolites and a prolonged half-life of cortisol are useful for the diagnosis. Dexamethasone and/or potassium sparing diuretics have been used for medication of AME. Licorice ingestion induces a mineralocorticoid excess state, and it seems that this is the result of acquired inhibition of 11 beta-DH by glycyrrhetinic acid. The existence of a second 11 beta-OHSD isoform has been suggested strongly for a long time, and recently, a human 11 beta-OHSD 2 cDNA has been isolated. It appears that 11 beta-OHSD 2 conveys specificity upon the renal MR, and a defect in its activity seems likely to account for the phenotype of AME.

Role of glucocorticoid in the development of glycyrrhizin-induced hypertension

Role of alterations of corticosterone metabolism in the expression of the mineralocorticoid activity of glycyrrhizin was explored in rats. While the mineralocorticoid actions of oral glycyrrhizin were not observed in bilaterally adrenalectomized rats and dexamethasone treated rats, the mineralocorticoid actions of glycyrrhizin were fully expressed in bilaterally adrenalectomized rats supplemented with physiological doses of corticosterone. Similar mineralocorticoid actions were observed in rats given glycyrrhizin, deoxycorticosterone and pharmacological doses of corticosterone. Although increases in mean blood pressure were suppressed only by concurrent administration of spironolactone to glycyrrhizin- and deoxycorticosterone-treated rats, increases in mean blood pressure were attenuated by both the glucocorticoid antagonist RU 38486 and spironolactone in pharmacological doses of corticosterone administered rats. Pressor responses to norepinephrine and angiotensin II infusions in rats given deoxycorticosterone and pharmacological doses of corticosterone were significantly higher than in glycyrrhizin-treated rats. These results confirmed the functional significance of 11-beta-hydroxysteroid dehydrogenase in expression of the mineralocorticoid activity of glycyrrhizin.