Gene expression of 11beta-hydroxysteroid dehydrogenase type 1 and type 2 in the kidneys of insulin-dependent diabetic rats

Decreased 11β-Hydroxysteroid Dehydrogenase Type 2 Expression in the Kidney May Contribute to Nicotine/Smoking-Induced Blood Pressure Elevation in Mice

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Glucocorticoid Metabolism in Obesity and Following Weight Loss

Glucocorticoids are steroid hormones produced by the adrenal cortex and are essential for the maintenance of various metabolic and homeostatic functions. Their function is regulated at the tissue level by 11β-hydroxysteroid dehydrogenases and they signal through the glucocorticoid receptor, a ligand-dependent transcription factor. Clinical observations have linked excess glucocorticoid levels with profound metabolic disturbances of intermediate metabolism resulting in abdominal obesity, insulin resistance and dyslipidaemia. In this review, we discuss the physiological mechanisms of glucocorticoid secretion, regulation and function, and survey the metabolic consequences of excess glucocorticoid action resulting from elevated release and activation or up-regulated signaling. Finally, we summarize the reported impact of weight loss by diet, exercise, or bariatric surgery on circulating and tissue-specific glucocorticoid levels and examine the therapeutic possibility of reversing glucocorticoid-associated metabolic disorders.

11β-HSD1 inhibition ameliorates diabetes-induced cardiomyocyte hypertrophy and cardiac fibrosis through modulation of EGFR activity

11β-HSD1 has been recognized as a potential therapeutic target for type 2 diabetes. Recent studies have shown that hyperglycemia leads to activation of 11β-HSD1, increasing the intracellular glucocorticoid levels. Excess glucocorticoids may lead to the clinical manifestations of cardiac injury. Therefore, the aim of this study is to investigate whether 11β-HSD1 activation contributes to the development of diabetic cardiomyopathy. To investigate the role of 11β-HSD1, we administered a selective 11β-HSD1 inhibitor in type 1 and type 2 murine models of diabetes and in cultured cardiomyocytes. Our results show that diabetes increases cortisone levels in heart tissues. 11β-HSD1 inhibitor decreased cortisone levels and ameliorated all structural and functional features of diabetic cardiomyopathy including fibrosis and hypertrophy. We also show that high levels of glucose caused cardiomyocyte hypertrophy and increased matrix protein deposition in culture. Importantly, inhibition of 11β-HSD1 attenuated these changes. Moreover, we show that 11β-HSD1 activation mediates these changes through modulating EGFR phosphorylation and activity. Our findings demonstrate that 11β-HSD1 contributes to the development of diabetic cardiomyopathy through activation of glucocorticoid and EGFR signaling pathway. These results suggest that inhibition of 11β-HSD1 might be a therapeutic strategy for diabetic cardiomyopathy, which is independent of its effects on glucose homeostasis.

Maternal corticosterone exposure in the mouse programs sex-specific renal adaptations in the renin-angiotensin-aldosterone system in 6-month offspring

Short‐term maternal corticosterone (Cort) administration at mid‐gestation in the mouse reduces nephron number in both sexes while programming renal and cardiovascular dysfunction in 12‐month male but not female offspring. The renal renin–angiotensin–aldosterone system (RAAS), functions in a sexually dimorphic manner to regulate both renal and cardiovascular physiology. This study aimed to identify if there are sex‐specific differences in basal levels of the intrarenal RAAS and to determine the impact of maternal Cort exposure on the RAAS in male and female offspring at 6 months of age. While intrarenal renin concentrations were higher in untreated females compared to untreated males, renal angiotensin II concentrations were higher in males than females. Furthermore, basal plasma aldosterone concentrations were greater in females than males. Cort exposed male but not female offspring had reduced water intake and urine excretion. Cort exposure increased renal renin concentrations and elevated mRNA expression of Ren1, Ace2, and Mas1 in male but not female offspring. In addition, male Cort exposed offspring had increased expression of the aldosterone receptor, Nr3c2 and renal sodium transporters. In contrast, Cort exposure increased Agtr1a mRNA levels in female offspring only. This study demonstrates that maternal Cort exposure alters key regulators of renal function in a sex‐specific manner at 6 months of life. These finding likely contribute to the disease outcomes in male but not female offspring in later life and highlights the importance of renal factors other than nephron number in the programming of renal and cardiovascular disease.

Hypothalamic-pituitary-adrenal axis activity is associated with the prevalence of chronic kidney disease in diabetic patients

Progression of chronic kidney disease (CKD) in diabetic patients can occur through enhanced hypothalamic-pituitary-adrenal (HPA) axis activity. The purpose of our study was to determine whether HPA axis activity influences the prevalence of CKD in patients with type 2 diabetes mellitus. Seventy-seven diabetic patients (mean age, 60 years) were enrolled. CKD was defined by K/DOQI criteria, and serum cortisol level was measured after the 1 mg overnight dexamethasone suppression test (F-DST). F-DST values were significantly negatively correlated with estimated glomerular filtration rate (eGFR), and significantly positively correlated with cystatin C level and spot urine albumin to creatinine ratio in simple and multiple regression analyses. The subjects were divided into 3 groups (low, middle, and high) according to the F-DST, and the odds for CKD were 8.7-fold (95% confidence interval 2.56 to 29.6, P=0.01) and 12.5-fold (95% confidence interval 3.3 to 47.9, P<0.001) higher in subjects in the middle and high groups than those in the low group, respectively. In multivariate regression analysis, subjects in the middle group and high group (compared to those in the low group) had 13.0-fold (95% confidence interval, 2.9 to 58.8 and P=0.001) and 14.7-fold (95% confidence interval, 2.8 to 78.5 and P=0.002), respectively, higher risk for CKD. In conclusion, F-DST values have a relationship with decreased eGFR and increased cystatin C or albumin excretion involved in CKD, and enhanced HPA axis activity may be an independent risk factor for CKD in patients with type 2 diabetes mellitus.

Targeting AGEs Signaling Ameliorates Central Nervous System Diabetic Complications in Rats

Diabetes is a chronic endocrine disorder associated with several complications as hypertension, advanced brain aging, and cognitive decline. Accumulation of advanced glycation end products (AGEs) is an important mechanism that mediates diabetic complications. Upon binding to their receptor (RAGE), AGEs mediate oxidative stress and/or cause cross-linking with proteins in blood vessels and brain tissues. The current investigation was designed to investigate the effect of agents that decrease AGEs signaling, perindopril which increases soluble RAGE (sRAGE) and alagebrium which cleaves AGEs cross-links, compared to the standard antidiabetic drug, gliclazide, on the vascular and central nervous system (CNS) complications in STZ-induced (50 mg/kg, IP) diabetes in rats. Perindopril ameliorated the elevation in blood pressure seen in diabetic animals. In addition, both perindopril and alagebrium significantly inhibited memory decline (performance in the Y-maze), neuronal degeneration (Fluoro-Jade staining), AGEs accumulation in serum and brain, and brain oxidative stress (level of reduced glutathione and activities of catalase and malondialdehyde). These results suggest that blockade of AGEs signaling after diabetes induction in rats is effective in reducing diabetic CNS complications.

11β-hydroxysteroid dehydrogenases: intracellular gate-keepers of tissue glucocorticoid action

Glucocorticoid action on target tissues is determined by the density of "nuclear" receptors and intracellular metabolism by the two isozymes of 11β-hydroxysteroid dehydrogenase (11β-HSD) which catalyze interconversion of active cortisol and corticosterone with inert cortisone and 11-dehydrocorticosterone. 11β-HSD type 1, a predominant reductase in most intact cells, catalyzes the regeneration of active glucocorticoids, thus amplifying cellular action. 11β-HSD1 is widely expressed in liver, adipose tissue, muscle, pancreatic islets, adult brain, inflammatory cells, and gonads. 11β-HSD1 is selectively elevated in adipose tissue in obesity where it contributes to metabolic complications. Similarly, 11β-HSD1 is elevated in the ageing brain where it exacerbates glucocorticoid-associated cognitive decline. Deficiency or selective inhibition of 11β-HSD1 improves multiple metabolic syndrome parameters in rodent models and human clinical trials and similarly improves cognitive function with ageing. The efficacy of inhibitors in human therapy remains unclear. 11β-HSD2 is a high-affinity dehydrogenase that inactivates glucocorticoids. In the distal nephron, 11β-HSD2 ensures that only aldosterone is an agonist at mineralocorticoid receptors (MR). 11β-HSD2 inhibition or genetic deficiency causes apparent mineralocorticoid excess and hypertension due to inappropriate glucocorticoid activation of renal MR. The placenta and fetus also highly express 11β-HSD2 which, by inactivating glucocorticoids, prevents premature maturation of fetal tissues and consequent developmental "programming." The role of 11β-HSD2 as a marker of programming is being explored. The 11β-HSDs thus illuminate the emerging biology of intracrine control, afford important insights into human pathogenesis, and offer new tissue-restricted therapeutic avenues.

Reduction of hepatic glucocorticoid receptor and hexose-6-phosphate dehydrogenase expression ameliorates diet-induced obesity and insulin resistance in mice

Intracellular glucocorticoid (GC) receptor (GR) function determines tissue sensitivity to GCs and strongly affects the development of type 2 diabetes and obesity. 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) mediates intracellular steroid exposure to mouse liver GR by prereceptor reactivation of GCs and is crucially dependent on hexose-6-phosphate dehydrogenase (H6PDH)-generating NADPH system. Pharmacological inhibition of 11beta-HSD1 improves insulin intolerance and obesity. Here, we evaluated the potential beneficial effects of 11beta-HSD1 inhibitor carbenoxolone (CBX) in diet-induced obese (DIO) and insulin-resistant mice by examining the possible influence of CBX on the expression of GR, 11beta-HSD1, and H6PDH in vivo and in vitro in hepatocytes. Treatment of DIO mice with CBX markedly reduced hepatic GR mRNA levels and reduced weight gain, hyperglycemia, and insulin resistance. The reduction of hepatic GR gene expression was accompanied by CBX-induced inhibition of both 11beta-HSD1 and H6PDH activity and mRNA in the liver. Moreover, CBX treatment also suppressed the expression of both phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase enzyme (G6Pase) mRNA and improved hepatic [1, 2-(3)H] deoxy-d-glucose uptake in DIO mice. In addition, the treatment of primary cultures of hepatocytes with increasing concentrations of CBX led to a dose-dependent downregulation of GR mRNA levels, which correlated with the suppression of both 11beta-HSD1 and H6PDH activity and their gene expression. Addition of CBX to primary hepatocytes also resulted in suppression of both PEPCK and G6Pase mRNA levels. These findings suggest that CBX exerts some of its beneficial effects, at least in part, by inhibiting hepatic GR and H6PDH expression.

Increased glucocorticoid receptor and 11{beta}-hydroxysteroid dehydrogenase type 1 expression in hepatocytes may contribute to the phenotype of type 2 diabetes in db/db mice

Excess tissue glucocorticoid action may contribute to the hyperglycemia and insulin resistance associated with type 2 diabetes, but the associated mechanisms are poorly understood. 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts inactive 11-dehydrocorticosterone into active corticosterone, thus amplifying glucocorticoid receptor-mediated tissue glucocorticoid action, particularly in the liver. To examine the role of tissue glucocorticoid action in type 2 diabetes, we analyzed expression of glucocorticoid receptor and 11beta-HSD1 and their regulation by endogenous hormones in vivo and in vitro in hepatocytes from db/db mice (a model of type 2 diabetes). We observed positive relations between expression of both glucocorticoid receptor and 11beta-HSD1 in liver and insulin sensitivity and expression of PEPCK mRNA in db/db mice and db/+ controls. Increased expression of glucocorticoid receptor and 11beta-HSD1 in the liver of db/db mice was correlated with elevated circulating levels of corticosterone, insulin, and blood glu-cose. Treatment of db/db mice with glucocorticoid antagonist RU486 reversed the increases in the expression of glucocorticoid receptor and 11beta-HSD1 within the liver and attenuated the phenotype of type 2 diabetes. Addition of corticosterone to db/db mouse primary hepatocytes activated expression of glucocorticoid receptor, 11beta-HSD1, and PEPCK, and these effects were abolished by RU486. Incubation of primary hepatocytes with increasing concentrations of glucose caused dose-dependent increases in glucocorticoid receptor and 11beta-HSD1 expression, whereas insulin did not affect the expression of 11beta-HSD1 and glucocorticoid receptor in primary hepatocytes. These findings suggest that activation of glucocorticoid receptor and 11beta-HSD1 expression within the liver may contribute to the development of type 2 diabetes in db/db mice.

Streptozotocin-induced diabetes in the pregnant rat reduces 11 beta-hydroxysteroid dehydrogenase type 2 expression in placenta and fetal kidney

Several epidemiological and animal studies have shown that the offsprings of diabetic mothers have higher incidences of glucose intolerance, obesity, insulin resistance, and hypertension in later life. It is well known that glucocorticoid metabolism plays a crucial role on several adult disease originated from fetal environment. The aim of this study was to investigate the relation between diabetic pregnancy and glucocorticoid metabolism of both mother and fetus, focusing on the 11 beta-hydroxysteroid dehydrogenase (11beta-HSD) type 2. A model of diabetic pregnancy was made by intravenous injection of streptozotocin (35 mg/kg body weight) to Sprague-Dawley rats, and blood and tissue samples were collected on day 20 of pregnancy. In the diabetic group, expression of 11 beta-hydroxysteroid dehydrogenase type 2 in placentas and fetal kidneys was decreased remarkably. Corticosterone levels of diabetic mothers were lower than those of control rats. Despite the differences in maternal corticosterone levels, fetal levels of corticosterone did not differ between the groups. Our results lend support to the concept that diabetic pregnancy imprints glucocorticoid regulation in these fetuses, which may contribute to their increased incidence of higher blood pressure as adults.

Different responsiveness in body weight and hepatic 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 mrna to 11beta-HSD inhibition by glycyrrhetinic acid treatment in obese and lean zucker rats

Tissue-specific dysregulation of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) activity in obese humans and animals may be associated with obesity and the metabolic syndrome. We investigated the effect of inhibition of 11beta-HSD with glycyrrhetinic acid (GE), an effective 11beta-HSD inhibitor, on body weight regulation in obese Zucker rats, which have a defect in the leptin receptor gene. GE (280 mg/kg/d) was administered in drinking water to 8-week-old male Zucker rats for 14 weeks. GE had no effect on food intake or weight gain, and did not affect hepatic 11beta-HSD1 and renal 11beta-HSD2 mRNA levels in obese rats. In contrast, average daily food intake and body weight on week 14 were significantly reduced by GE in lean rats (both P <.0001). Hepatic 11beta-HSD1 and renal 11beta-HSD2 mRNA levels were also significantly decreased by GE in lean rats (both P <.05). GE had no significant effect on plasma corticosterone levels in obese rats but lowered them in lean rats (P <.05). Plasma leptin levels declined in both GE-treated obese and lean rats (both P <.01). In conclusion, long-term GE treatment decreased weight gain in lean Zucker rats but not in obese Zucker rats. These findings suggest that the differing responses of 11beta-HSD1 to GE in obese and lean Zucker rats are closely associated with the different weight-gain responses. Furthermore, the weight-lowering effect of GE may require intact leptin receptors.

Characterisation of 11β-hydroxysteroid dehydrogenases in feline kidney and liver

11 Beta-hydroxysteroid dehydrogenases type 1 and 2 (11 beta-HSD1 and 11 beta-HSD2) are microsomal enzymes responsible for the interconversion of cortisol into the inactive form cortisone and vice versa. 11 beta-HSD1 is mainly present in the liver, and has predominantly reductase activity although its function has not yet been elucidated. 11 beta-HSD2, present in mineralocorticoid target tissues such as the kidney, converts cortisol into cortisone. Reduced activity due to inhibition or mutations of 11 beta-HSD2 leads to hypertension and hypokalemia resulting in the Apparent Mineralocorticoid Excess Syndrome (AMES). Like humans, cats are highly susceptible for hypertension. As large species differences exist with respect to the kinetic parameters (K(m) and V(max)) and amino acid sequences of both enzymes, we determined these characteristics in the cat. Both enzyme types were found in the kidneys. 11 beta-HSD1 in the feline kidney showed bidirectional activity with predominantly dehydrogenase activity (dehydrogenase: K(m) 1959+/-797 nM, V(max) 766+/-88 pmol/mg*min; reductase: K(m) 778+/-136 nM, V(max) 112+/-4 pmol/mg*min). 11 beta-HSD2 represents a unidirectional dehydrogenase with a higher substrate affinity (K(m) 184+/-24 nM, V(max) 74+/-3 pmol/mg*min). In the liver, only 11 beta-HSD1 is detected exerting reductase activity (K(m) 10462 nM, V(max) 840 pmol/mg*min). Sequence analysis of conserved parts of 11 beta-HSD1 and 11 beta-HSD2 revealed the highest homology of the feline enzymes with the correspondent enzymes found in man. This suggests that the cat may serve as a suitable model species for studies directed to the pathogenesis and treatment of human diseases like AMES and hypertension.

Leptin activation of corticosterone production in hepatocytes may contribute to the reversal of obesity and hyperglycemia in leptin-deficient ob/ob mice

Glucocorticoids have been implicated as pathophysiological mediators of obesity and insulin resistance and are regulated by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). This enzyme regenerates active corticosterone from inactive 11-keto forms. To assess the role of 11beta-HSD1-mediated synthesis of active corticosterone in leptin-related obesity and diabetes, we examined the peripheral effect of leptin on 11beta-HSD1 activity and gene expression in vivo and in vitro in hepatocytes from ob/ob mice and in liver of streptozotocin (STZ)-treated ob/ob mice. We observed an inverse relationship between hepatic 11beta-HSD1 expression and body weight in ob/ob mice and lean littermates. Leptin treatment of ob/ob mice markedly increased hepatic 11beta-HSD1 activity and mRNA expression. This induction of 11beta-HSD1 expression corresponded to reduced levels of circulating corticosterone and weight loss in ob/ob mice treated with leptin, indicating that impaired hepatic 11beta-HSD1 expression may contribute to the pathogenesis of obesity in ob/ob mice. In addition, leptin treatment of STZ-treated ob/ob mice caused marked increases in hepatic 11beta-HSD1 levels associated with decreased body weight and a significant reduction in hyperglycemia due to pancreatic beta-cell damage. Addition of leptin to ob/ob mouse primary hepatocytes led to a dose-dependent increase in 11beta-HSD1 mRNA expression. In contrast, leptin did not influence 11beta-HSD1 expression in primary hepatocytes from db/db mice, indicating that leptin regulation of 11beta-HSD1 expression is probably mediated by the functional leptin receptor. Thus, leptin appears to be an important metabolic signal that directly activates intrahepatic corticosterone production. These findings suggest that the liver-specific interaction of leptin with 11beta-HSD1 is involved in the development of obesity and insulin resistance in ob/ob mice.

TNF-alpha enhances intracellular glucocorticoid availability

For understanding the mechanism(s) relating inflammation to corticosteroid action, the effect of tumour necrosis factor-alpha (TNF-alpha) on 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), the enzyme regulating access of 11beta-hydroxycorticosteroids to receptors, was studied in LLC-PK(1) cells. We observed (i) NAD-dependent enzyme activity and mRNA for 11beta-HSD2, but not 11beta-HSD1, (ii) increasing 11beta-HSD2 activity with increasing degree of differentiation and (iii) a concentration-dependent down-regulation by TNF-alpha, phorbol myristate acetate (PMA) or glucose of activity and mRNA of 11beta-HSD2. The decrease of activity and mRNA by glucose and PMA, but not that by TNF-alpha, was abrogated by the protein kinase C inhibitor GF-109203X. The effect of TNF-alpha on 11beta-HSD2 was reversed by inhibiting the mitogen-activated protein kinases ERK with PD-098050 and p38 by SB-202190, or by activating protein kinase A with forskolin. Overexpression of MEK1, an ERK activator, down-regulated the 11beta-HSD2 activity. In conclusion, TNF-alpha decreases 11beta-HSD2 activity and thereby enhances glucocorticoid access to glucocorticoid receptors to modulate the inflammatory response.

Effect of angiotensin II on rat renal cortical 11beta-hydroxysteroid dehydrogenase

Renal 11beta-hydroxysteroid dehydrogenases (11beta-HSDs) are subject to modulation by various endogenous factors. 11beta-HSDs convert glucocorticoids into inactive 11-ketones and thereby determine tissue levels of active glucocorticoids and thus the extent of glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) activation. As such, modulation of the activity of renal 11beta-HSDs may contribute to the cascade of regulatory events involved in renal electrolyte water handling. We investigated whether renal 11beta-HSDs are modulated by elevated circulating angiotensin II. In rats infused for 2 wk with angiotensin II (250 ng/[kg x min] subcutaneously), plasma angiotensin II, aldosterone, and corticosterone were raised 5.1-, 10.7-, and 2.3-fold, respectively, compared with control rats. Angiotensin II infusion raised corticosterone 11beta-oxidation 1.46- and 1.35-fold in renal cortical proximal and distal tubules (enriched by Percoll centrifugation), respectively, but had no effect on 11beta-HSD1 and 11beta-HSD2 mRNA levels (semiquantitative reverse transcriptase polymerase chain reaction), except for distal tubular 11beta-HSD1 mRNA, which was decreased to 50%. In vitro treatment of freshly isolated tubules with angiotensin II for 45 min prior to assessment of 11beta-HSD activity showed no direct acute effects of angiotensin II on tubular corticosterone 11beta-oxidation. The enhanced renal tubular corticosterone 11beta-oxidation in vivo may partly protect renal GR and MR from elevated plasma corticosterone on angiotensin II infusion.

Effects of spironolactone on systolic blood pressure in experimental diabetic rats

BACKGROUND

Mineralocorticoid hormones, which maintain electrolyte balance and blood pressure, are thought to be associated not only with the expression of renal 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), but also with that of intracellular mineralocorticoid receptors (MRs). The present study was designed to test whether the mineralocorticoid action of glucocorticoid corticosterone on renal MR is involved in the development of diabetes-associated hypertension by measuring the alterations of renal 11beta-HSD2.

METHOD

We measured the mean systolic blood pressure, renal 11beta-HSD1, and mRNA levels in streptozotocin (STZ)-induced diabetic rats that received spironolactone, insulin, or no treatment, and in nondiabetic controls that received spironolactone.

RESULTS

Four weeks after an injection of STZ, the renal 11beta-HSD2 and mRNA levels were significantly lower in diabetic rats than in control rats, and the mean systolic blood pressure was 14.8% higher in diabetic rats than in controls. Subcutaneous injections of spironolactone into diabetic rats for three weeks partially reversed the decrease in renal 11beta-HSD2 activity and gene expression, and prevented the mean systolic blood pressure elevation. Spironolactone treatment for one week also resulted in a significant reduction in mean systolic blood pressure during the development of diabetic hypertension. However, treatment with STZ did not significantly decrease the renal 11beta-HSD1 activity and mRNA expression, and spironolactone treatment did not exert a significant effect on this enzyme in STZ-induced diabetic rats.

CONCLUSION

In the development of diabetes-induced hypertension, the effect of spironolactone on mean systolic blood pressure may be associated with the mineralocorticoid effects of corticosterone on renal MR, as well as an alteration of renal 11beta-HSD2 activity and its mRNA expression in insulin-dependent diabetic rats.

Influence of placental 11beta-hydroxysteroid dehydrogenase (11beta-HSD) inhibition on glucose metabolism and 11beta-HSD regulation in adult offspring of rats

Placental 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) converts glucocorticoids to 11-keto-products and is believed to play an important role in protecting fetuses from higher maternal glucocorticoid levels. Recent reports have speculated that prenatal glucocorticoid exposure leads to fetal growth retardation and adult offspring hypertension and hyperglycemia. To investigate the effects of placental 11beta-HSD2 inhibition on glucose metabolism and the 11beta-HSD system in adult offspring, pregnant rats were treated with daily injections of carbenoxolone (CBX), an inhibitor of 11beta-HSD. The offspring of the maternal CBX treatment group showed reduced birth weight (treated v control, 5.6 +/- 0.5 v 6.4 +/- 0.4 g, P < .0001). In adult offspring of the maternal CBX treatment group, plasma hemoglobin A1c was significantly increased (7.3% +/- 1.8% v 4.8% +/- 0.3%, P < .01) and glucose intolerance was shown on the oral glucose tolerance test. The gene expression of hepatic 11beta-HSD1 and renal 11beta-HSD2 was decreased 87.6% (P < .05) and 52.3% (P < .01) in adult offspring of the maternal CBX treatment group, whereas renal 11beta-HSD1 was not significantly altered. The change in 11beta-HSD activity corresponded to the change in the gene expression. These results suggest that inhibition of placental 11beta-HSD2 causes growth retardation, glucose intolerance, and partial suppression of the 11beta-HSD system in the offspring.

High dietary potassium chloride intake augments rat renal mineralocorticoid receptor selectivity via 11beta-hydroxysteroid dehydrogenase

Glucocorticoid access to renal corticosteroid receptors is regulated by 11beta-hydroxysteroid dehydrogenases (11beta-HSDs), converting 11beta-hydroxyglucocorticoids into inactive 11-ketones. This mechanism plays a key role in maintaining normal salt-water homeostasis and blood pressure. To study whether renal cortical proximal and distal tubular 11beta-HSDs are modulated, upon shifting the electrolyte status (and may thereby contribute to adjusting the salt-water homeostasis), rats were treated for 14 days with diets with low (0.058 w/w%), normal (0.58%, which is the KCl content of standard European laboratory rat food) or high (5.8%) potassium chloride content. In proximal tubules, dietary KCl had no effect regarding corticosterone 11beta-oxidation in intact cells as well as 11beta-HSD1 and 11beta-HSD2 protein (Western blotting) and mRNA levels (semi-quantitative RT-PCR). In distal tubules, the low KCl diet also had no effect. However, distal tubules of rats fed the high KCl diet showed increased corticosterone 11beta-oxidation rates (1.6-fold, P<0.01) and 11beta-HSD2 protein (4-fold, P<0.01), whereas 11beta-HSD1 protein was decreased (no longer detected, P<0.05). Distal tubular 11beta-HSD mRNA levels were not changed upon dietary treatment. Our results suggest that upon dietary KCl loading distal tubular mineralocorticoid receptor selectivity for aldosterone is increased because of enhanced corticosterone 11beta-oxidation. This may contribute to the fine-tuning of salt-water homeostasis by the kidney.