Visceral obesity may be due to the dysregulation of cortisol production or metabolism that lead to metabolic disease. In adipose tissue, the enzyme 11beta-hydroxysteroid dehydrogenase type 1 regulates cortisol metabolism (11beta-HSD1). A previous study showed an increase in the visceral fat deposition in adrenalectomised rats given intramuscular dexamethasone. Glycyrrhizic acid (GCA) has been shown to reduce fat deposition because it is a known potent inhibitor of the 11beta-HSD1 enzyme. Piper sarmentosum (PS) is an edible medicinal plant commonly used in Asia as traditional medicine for treating diabetes, hypertension and joint pains. In this study, we determined the effects of PS extract on the disposition and morphology of perirenal adipocytes of adrenalectomised rats given intramuscular dexamethasone.
Glycyrrhizin (glycyrrhizic acid), a bioactive triterpenoid saponin constituent of Glycyrrhiza glabra, is a traditional medicine possessing a plethora of pharmacological anti-inflammatory, antioxidant, antimicrobial, and antiaging properties. It is a known pharmacological inhibitor of high mobility group box 1 (HMGB1), a ubiquitous protein with proinflammatory cytokine-like activity. HMGB1 has been implicated in an array of inflammatory diseases when released extracellularly, mainly by activating intracellular signaling upon binding to the receptor for advanced glycation end products (RAGE) and toll-like receptor 4 (TLR4). HMGB1 neutralization strategies have demonstrated disease-modifying outcomes in several preclinical models of neurological disorders. Herein, we reveal the potential neuroprotective effects of glycyrrhizin against several neurological disorders. Emerging findings demonstrate the therapeutic potential of glycyrrhizin against several HMGB1-mediated pathological conditions including traumatic brain injury, neuroinflammation and associated conditions, epileptic seizures, Alzheimer's disease, Parkinson's disease, and multiple sclerosis. Glycyrrhizin's effects in neurological disorders are mainly attributed to the attenuation of neuronal damage by inhibiting HMGB1 expression and translocation as well as by downregulating the expression of inflammatory cytokines. A large number of preclinical findings supports the notion that glycyrrhizin might be a promising therapeutic alternative to overcome the shortcomings of the mainstream therapeutic strategies against neurological disorders, mainly by halting disease progression. However, future research is warranted for a deeper exploration of the precise underlying molecular mechanism as well as for clinical translation.
Oxidative stress, lipid peroxidation, and transaminase reactions are some of the mechanisms that can lead to liver dysfunction. A time-dependent study was designed to evaluate the ability of silymarin (SLN) and glycyrrhizin (GLN) in different dosage regimens to lessen oxidative stress in the rats with hepatic injury caused by the hepatotoxin carbon tetrachloride. Wistar male albino rats (n = 60) were randomly assigned to six groups. Group A served as a positive control while groups B, C, D, E, and F received a dose of CCl4 (50% solution of CCl4 in liquid paraffin, 2 mL/kg, intraperitoneally) twice a week to induce hepatic injury. Additionally, the animals received SLN and GLN in different doses for a period of six weeks. CCl4 was found to induce hepatic injury by significantly increasing serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and thiobarbituric acid reactive substances while decreasing total protein and the activities of reduced glutathione, superoxide dismutase, and catalase. Treatment with various doses of SLN and GLN significantly reduced ALT, AST, ALP, and TBARS levels and increased GSH, SOD, and CAT levels. Our findings indicated that SLN and GLN have hepatoprotective effects against oxidative stress of the liver.
Glycyrrhizic acid (GA) ameliorates many components of the metabolic syndrome, but its potential therapeutic use is marred by edema caused by inhibition of renal 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2). We assessed whether 100 mg/kg per day GA administered orally could promote metabolic benefits without causing edema in rats fed on a high-sucrose diet. Groups of eight male rats were fed on one of three diets for 28 days: normal diet, a high-sucrose diet, or a high-sucrose diet supplemented with GA. Rats were then culled and renal 11β-HSD2 activity, as well as serum sodium, potassium, angiotensin II and leptin levels were determined. Histological analyses were performed to assess changes in adipocyte size in visceral and subcutaneous depots, as well as hepatic and renal tissue morphology. This dosing paradigm of GA attenuated the increases in serum leptin levels and visceral, but not subcutaneous adipocyte size caused by the high-sucrose diet. Although GA decreased renal 11β-HSD2 activity, it did not affect serum electrolyte or angiotensin II levels, indicating no onset of edema. Furthermore, there were no apparent morphological changes in the liver or kidney, indicating no toxicity. In conclusion, it is possible to reap metabolic benefits of GA without edema using the current dosage and treatment time.
Glycyrrhizic acid (GCA) the active component of liquorice acts by inhibiting 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD) which catalyses the reversible conversion of cortisol to cortisone. The aim of this study was to examine the effect of GCA on pulmonary arterial pressure. Male Sprague-Dawley rats (200g) received drinking water containing 0.1 mg/ml and 1.0 mg/ml GCA for 12 weeks. Tail blood pressure (BP) was recorded every three weeks and serum Na+ and K+ were measured at the beginning and the end of the experiment. Right atrial pressure (RAP) were measured at the end of 12 weeks just before the animals were sacrificed. Lung tissues were taken for histological examination using the elastic-van Gieson (EVG) staining method. There was a significant increase in tail BP in GCA treated rats compared to controls, for both dosages used. This was associated with an increase in serum Na+ and a decrease in K+ level. The mean RAP increased significantly from 2.69 +/- 0.23 mmHg to 4.47 +/- 0.32 mmHg (P < 0.001) in 0.1 mg/ml GCA treated rats and 6.86 +/- 0.54 mmHg (P < 0.0001) in rats receiving 1.0 mg/ml GCA in their drinking water. Histological examination showed increased thickness of pulmonary arterial wall (P < 0.0001). In conclusion GCA caused an increase in right atrial pressure as well as thickening of the pulmonary vessels suggesting pulmonary hypertension.
The metabolic syndrome (MetS) is a cluster of metabolic abnormalities comprising visceral obesity, dyslipidaemia and insulin resistance (IR). With the onset of IR, the expression of lipoprotein lipase (LPL), a key regulator of lipoprotein metabolism, is reduced. Increased activation of glucocorticoid receptors results in MetS symptoms and is thus speculated to have a role in the pathophysiology of the MetS. Glycyrrhizic acid (GA), the bioactive constituent of licorice roots (Glycyrrhiza glabra) inhibits 11beta-hydroxysteroid dehydrogenase type 1 that catalyzes the activation of glucocorticoids. Thus, oral administration of GA is postulated to ameliorate the MetS.
11 beta-Hydroxysteroid dehydrogenase (11 beta-OHSD) is a microsomal enzyme that catalyzes the dehydrogenation of cortisol (F) to cortisone (E) in man and corticosterone (B) to 11-dehydrocorticosterone (A) in rats. 11 beta-OHSD has been identified in a wide variety of tissues. The differential distribution of 11 beta-OHSD suggests that this enzyme has locally defined functions that vary from region to region. The aim of this study was to investigate the effects of the glucocorticoids B and dexamethasone (DM), the mineralocorticoid deoxycorticosterone (DOC), and the inhibitors of 11 beta-OHSD glycyrrhizic acid (Gl) and glycyrrhetinic acid (GE) on 11 beta-OHSD bioactivity at the hypothalamus (HT) and anterior pituitary (AP). Male Wistar rats were treated with GI or were adrenalectomized (ADX) and treated with either B, DM, or DOC for 7 days. All treatments were in vivo except GE, which was used in vitro. At the end of treatment, homogenates of HT and AP were assayed for 11 beta-OHSD bioactivity, expressed as the percentage conversion of B to A in the presence of NADP, 11 beta-OHSD bioactivity is significantly higher (P < 0.0001) in the AP compared with the HT. Adrenalectomy significantly increased the enzyme activity in the AP (P < 0.05), an effect reversed by B or DM. ADX rats treated with DOC showed decreased enzyme activity in the AP (P < 0.001) but increased the activity in the HT (P < 0.0001). Gl increased activity in both HT and AP, whereas GE decreased activity significantly. We conclude that the modulation of 11 beta-OHSD is both steroid specific and tissue specific.