Effects of spironolactone on systolic blood pressure in experimental diabetic rats

Clinical effect of nonsteroidal mineralocorticoid receptor (MR) antagonists in the treatment of diabetic kidney disease: expectations as a new therapeutic strategy

Diabetes mellitus is the main cause of chronic kidney disease (CKD) in Japan and worldwide. Although angiotensin-converting enzyme (ACE) inhibitors and angiotensin II type 1 receptor blockers (ARBs) are basic drugs for the treatment of CKD with diabetes (diabetic kidney disease, DKD) with albuminuria and/or proteinuria, it has also become clear that the use of an ACE inhibitor or ARB alone is not fully sufficient. We have previously reported the clinical effects of mineralocorticoid receptor (MR) antagonists and recommended their use in addition to renin-angiotensin system inhibitors. Recently, new types of nonsteroidal MR antagonists have been developed, and the results of a large-scale study are expected. Nonsteroidal MR antagonists are distributed in the heart, lungs, liver, and kidneys when administered orally and are characterized by their equivalent distribution between the heart (nonepithelial tissue) and kidneys (epithelial tissue). We summarize the latest evidence regarding the use of nonsteroidal MR antagonists in the treatment of DKD. Hyperkalemia and renal dysfunction are frequent during MR antagonist treatment. However, with careful and combined monitoring of these two conditions, the effectiveness of MR antagonists will not be diminished; conversely, it is apparent that patients at such risk will benefit more from the addition of an MR antagonist to the treatment regimen. The most important measure against hyperkalemia is the regular monitoring of serum potassium levels and renal function. The safest and most reliable measure against hyperkalemia is the combined use of a new oral potassium adsorbent that has high potassium selectivity and few side effects. In DKD treatment, it is important to continue using MR antagonists without interruption as much as possible.

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

[Figure: see text].

Blockade of the TLR4-MD2 complex lowers blood pressure and improves vascular function in a murine model of type 1 diabetes

While the pathogenesis of diabetes-induced high blood pressure (BP) is not entirely clear, current evidence suggests that Toll-like receptor 4 (TLR4) is a key player in the mechanisms associated with hypertension. However, it is unknown whether this receptor affects BP under type 1 diabetes. Likewise, there is insufficient knowledge about the role of TLR4 in diabetes-associated vascular dysfunction of large arteries. To narrow these gaps, in this study, we investigated if blockade of the TLR4-MD2 complex impacts BP and vascular function in diabetic rats. We injected streptozotocin in male Sprague Dawley rats and treated them with a neutralizing anti-TLR4 antibody for 14 days. BP was directly measured in conscious animals at the end of the treatment. In another set of experiments, we excised the aorta from control and diabetic animals, and measured TLR4 and MD2—a co-receptor that confers functionality to TLR4—levels by Western blotting. We also performed functional studies and evaluated ROS levels with and without a pharmacological inhibitor for TLR4 as well as for MD2. Additionally, we scrutinized a large human RNA-Seq dataset of aortic tissue to assess the co-expression of TLR4, MD2, and subunits of the vascular NADPH oxidases under diabetes and hypertension. We report that (a) chronic blockade of the TLR4–MD2 complex lowers BP in diabetic animals; that (b) type 1 diabetes modulates the levels of MD2 expression in the aorta, but not TLR4, at least in the conditions evaluated in this study; and, that (c) acute inhibition of TLR4 or MD2 diminishes vascular contractility and reduces oxidative stress in the aorta of these animals. In summary, we show evidence that the TLR4–MD2 complex is involved in the mechanisms linking type 1 diabetes and hypertension.

Captopril and Spironolactone Can Attenuate Diabetic Nephropathy in Wistar Rats by Targeting microRNA-192 and microRNA-29a/b/c

Diabetes mellitus is a complicated metabolic disease characterized by hyperglycemia. Diabetic nephropathy (DN) is a progressive kidney disease, which results in mortality in diabetic patients. The present study was designed to investigate the effect of applying spironolactone (S), captopril (C), and their combination (S+C) on some renal performance indices and microRNAs' (miRNAs) expression. A total of 35 two-month-old male Wistar rats were provided for the study. Intraperitoneal injection of freshly dissolved streptozotocin (60 mg/kg) in cold citrate buffer was used to induce diabetes. Blood samples were examined through calorimetry to assess serum concentrations of glucose, blood urea nitrogen (BUN), and creatinine. To measure the microalbuminuria and transforming growth factor-β (TGF-β) levels and to evaluate the miRNAs expression levels of the kidney tissue, the ELISA method and the real-time PCR were used. The obtained results serve as in vivo evidence for the positive relationship between miR-192 and TGF-β levels in the DN rats. A significant increase and decrease were found for miR-29a/b/c and the miR-192 expression of DN after treatment with S, C, and S+C. TGF-β levels and microalbuminuria of diabetic rats also increased. The results obtained from this research study suggest that S, C, and S + C can improve DN by targeting miR-192 and miR-29 family and changing their expression. These findings suggest that miR-192 and miRs-29a/b/c can be potential targets for DN remediation.

Mineralocorticoid receptor blockade: new insights into the mechanism of action in patients with cardiovascular disease

Mineralocorticoid receptor (MR) blockade is effective in reducing total mortality and the incidence of heart failure in patients with systolic left ventricular dysfunction (SLVD) associated with chronic heart failure or post myocardial infarction.

Pre-clinical and clinical studies in SLVD have shown that MR blockade reduces sudden cardiac death, left ventricular remodelling, left ventricular hypertrophy, endothelial dysfunction, autonomic imbalance, renal dysfunction and improves fibrinolysis.

While MR blockade promotes sodium excretion and the combination of an angiotensin-converting enzyme inhibitor and a MR blocker have been shown to be more effective than either alone in causing natriuresis, it is unlikely that their beneficial effects can be explained solely on this basis.

Aldosterone has been shown to have a number of adverse effects, including activation of other neurohumeral mediators, stimulation of active reactive oxygen species (ROS), activation of the NF-κβ and AP-1 signalling pathways, vascular inflammation and fibrosis, myocardial hypertrophy, autonomic imbalance, and a decrease in fibrinolysis. MR blockade is, however, effective both in situations with and without an increase in serum aldosterone level, since the MR can be occupied and activated by cortisol as well as by aldosterone.

In view of these mechanisms, MR blockade may play an important role not only on SLVD, but also in essential hypertension with normal systolic function, diastolic heart failure, valvular heart disease, vascular stiffening with ageing, progression of renal disease, and diabetes mellitus. This hypothesis will, however, require further prospective evaluation.

The necessity and effectiveness of mineralocorticoid receptor antagonist in the treatment of diabetic nephropathy

Diabetes mellitus is a major cause of chronic kidney disease (CKD), and diabetic nephropathy is the most common primary disease necessitating dialysis treatment in the world including Japan. Major guidelines for treatment of hypertension in Japan, the United States and Europe recommend the use of angiotensin-converting enzyme inhibitors and angiotensin-receptor blockers, which suppress the renin-angiotensin system (RAS), as the antihypertensive drugs of first choice in patients with coexisting diabetes. However, even with the administration of RAS inhibitors, failure to achieve adequate anti-albuminuric, renoprotective effects and a reduction in cardiovascular events has also been reported. Inadequate blockade of aldosterone may be one of the reasons why long-term administration of RAS inhibitors may not be sufficiently effective in patients with diabetic nephropathy. This review focuses on treatment in diabetic nephropathy and discusses the significance of aldosterone blockade. In pre-nephropathy without overt nephropathy, a mineralocorticoid receptor antagonist can be used to enhance the blood pressure-lowering effects of RAS inhibitors, improve insulin resistance and prevent clinical progression of nephropathy. In CKD categories A2 and A3, the addition of a mineralocorticoid receptor antagonist to an RAS inhibitor can help to maintain 'long-term' antiproteinuric and anti-albuminuric effects. However, in category G3a and higher, sufficient attention must be paid to hyperkalemia. Mineralocorticoid receptor antagonists are not currently recommended as standard treatment in diabetic nephropathy. However, many studies have shown promise of better renoprotective effects if mineralocorticoid receptor antagonists are appropriately used.

The Effects of Captopril on Cardiac Regression, Blood Pressure and Bradykinin Components in Diabetic Wistar Kyoto Rats

The present study examined the left ventricular wall thickness (LVWT), total urinary kallikrein, total plasma kininogen and mean arterial blood pressure (MABP) in diabetic and non-diabetic Wistar Kyoto (WKY) rats. The MABP was significantly raised (P<0.01) in diabetic WKY rats compared to the respective controls. The LVWT was also significantly (P<0.01) increased in diabetic WKY rats than that of control WKY rats. The mean total urinary kallikrein level and the mean total plasma kininogen level were higher (P<0.01) in diabetic WKY rats, when these rats were treated with captopril (40 mg/kg and 80 mg/kg) against the mean value obtained from control WKY rats. In conclusion, this investigation suggests that diabetes induced in these rats can cause hypertension, increased LVWT and changes in the BK-forming components. Captopril treatment caused reduction in MABP, regression of LVWT and alterations in bradykinin (BK)-forming components. The possible significance of these observations is discussed.

Evaluation of blood pressure in Spontaneously Diabetic Torii-Lepr(fa) rats

The Spontaneously Diabetic Torii-Lepr(fa) (SDT-fa/fa) rat, a new model of obese type 2 diabetes, shows obesity, hyperglycemia, and hyperlipidemia from 6 weeks of age. Diabetic complications such as nephropathy and cataract are observed with aging; however, blood pressure change with age has not previously been examined. In this study, blood pressure was periodically measured and the change was investigated. Blood pressure in male SDT-fa/fa rats was elevated at 8, 16, and 24 weeks of age, whereas the heart rate was not changed. In addition to hyperglycemia, hyperlipidemia, and proteinuria, hyperleptinemia and increased urine angiotensinogen were observed in SDT-fa/fa rats. Blood pressure and heart rate in the male original SDT (SDT-+/+) rat did not significantly change. In conclusion, the SDT-fa/fa rat is a promising model, showing significant hypertension with diabetes mellitus.

Effect of the two new calcium channel blockers mebudipine and dibudipine in comparison to amlodipine on vascular flow of isolated kidney of diabetic rat

Calcium channel blockers are clinically useful vasodilators, used widely in the treatment of hypertension. These agents are reported to preserve or improve renal function in patients with essential hypertensive renal disease or diabetic renal disease. Among the classes of calcium channel blockers, dihydropyridine derivatives are widely used because of their potent vasodilating activity and weak cardiodepressant action. Mebudipine and dibudipine are two new 1,4-dihydropyridine calcium channel blockers that recently have been synthesized. In previous research mebudipine and dibudipine showed considerable relaxant effects on vascular and ileal smooth muscle cells. In this study we investigated the effects of these new drugs on vascular flow of isolated kidney of diabetic rat and compare their potencies to amlodipine. It is concluded that mebudipine and dibudipine (1-10 μM) are at least as potent as amlodipine in inhibiting PE-induced perfusion pressure in isolated kidney of diabetic rats. These new dihydropyridines improve kidney perfusion of diabetic rat in the setting of PE infusion. Similarly, amlodipine.

Age and sex differences in fat distribution in non-obese Japanese children

OBJECTIVE

To assess fat distribution in non-obese Japanese children and adolescents.

DESIGN

130 non-obese Japanese children (73 boys and 57 girls) from Kikugawa, Hamamatsu were included. The visceral fat area (VFA) and subcutaneous fat area (SFA) were measured by computed tomography (CT) and calculated (in cm(2)). Subjects were divided into three groups based on age: group A (6-10 years), group B (11-15 years), and group C (16-20 years).

RESULTS

Girls had more subcutaneous fat than boys in groups B and C (P<0.01). Boys had an age-dependent increase in visceral fat, but girls did not. In group C (16-20 years), boys had more visceral fat than girls (P<0.01).

CONCLUSIONS

In non-obese Japanese children, there are significant differences in visceral and subcutaneous fat amounts by age and sex. VFA seems to accumulate more in boys than in girls, and SFA is more prevalent in girls than boys.

Eplerenone, a selective mineralocorticoid receptor blocker, exerts anxiolytic effects accompanied by changes in stress hormone release

The aim of this study was to investigate the impact of chronic treatment with eplerenone, a mineralocorticoid receptor antagonist and clinically used antihypertensive drug, on animal correlates of mood disorders, namely anxiety-like behaviour, stress hormones release and brain plasticity. Male rats (n = 40) were injected subcutaneously twice daily with eplerenone (50 mg/kg body weight) or vehicle for 11 days. Open-field and elevated plus-maze tests were used as both anxiety-related paradigms and stress stimuli to evaluate hormone responses. Eplerenone-treated rats showed reduced anxiety-like behaviour manifested by both conventional and ethological parameters related to exploration and risk assessment behaviour in the elevated plus-maze test and partially in the open-field test. Eplerenone treatment resulted in an elevation of plasma aldosterone and oxytocin levels. Chronic treatment with eplerenone prevented the stress-induced rise in plasma corticosterone levels and vasopressin concentrations in the posterior pituitary. Eplerenone treatment failed to induce substantial changes in hippocampal brain derived neurotrophic factor protein concentrations. In conclusions, chronic treatment with eplerenone (1) exerts anxiolytic effects and (2) influences corticosterone, oxytocin and vasopressin concentrations in a manner consistent with the anxiolytic outcome.

Effect of spironolactone and captopril on nitric oxide and S-nitrosothiol formation in kidney of L-NAME-treated rats

Although angiotensin-converting enzyme (ACE) inhibitors are well-established drugs in the treatment of hypertension, they are not supposed to be sufficient in the inhibition of aldosterone formation. The present study analyzes the effect of aldosterone receptor antagonist, spironolactone and ACE inhibitor, captopril on nitric oxide (NO) and S-nitrosothiol formation in the kidney of N(G)-nitro-L-arginine methyl ester (L-NAME)-treated rats. Male Wistar rats were divided into six groups: (1) controls, (2) L-NAME (40 mg/kg/day), (3) spironolactone (200 mg/kg/day), (4) captopril (100 mg/kg/day), (5) L-NAME+spironolactone, and (6) L-NAME+captopril. After 4 weeks, NO synthase (NOS) activity, protein expression of endothelial NOS, inducible NOS and concentration of thiol and S-nitrosothiol groups were determined in the kidney. Besides the increase in systolic blood pressure (by 32%) and the decrease in NOS activity (by 37%), L-NAME treatment lowered the concentration of thiols (by 32%) and S-nitrosothiols (by 36%) in the renal tissue. Simultaneous treatment with spironolactone preserved NOS activity and S-nitrosothiols on the control level, whereas captopril did not affect these parameters modified by L-NAME treatment. Moreover, spironolactone increased expression of endothelial NOS protein without affecting inducible NOS protein expression. In conclusion, both captopril and spironolactone prevented L-NAME-induced hypertension and the decline of the antioxidant potential of the kidney tissue. However, only spironolactone improved NOS activity which led to the S-nitrosothiols formation. Both NO itself and S-nitrosothiols may contribute to the preventive effect of spironolactone against development of L-NAME-induced hypertension.

Salt-sensitive blood pressure—an intermediate phenotype predisposing to diabetic nephropathy?

BACKGROUND

Family studies point to important genetic determinants of diabetic nephropathy (DN). Blood pressure (BP) is higher in offspring of patients with type 2 diabetes and DN, but the pathomechanisms involved have not been elucidated.

METHODS

We examined the salt sensitivity of BP after 5 days equilibration on a low (20 mmol/day) vs high salt diet (220 mmol/day) in three matched groups of 15 subjects each: (i) control individuals; (ii) offspring of type 2 diabetic parents without DN (DN-); and (iii) offspring of type 2 diabetic parents with DN (DN+). Ambulatory BP and hormones involved in sodium homeostasis [plasma renin activity (PRA), aldosterone and atrial natriuretic peptide (ANP)] as well as the tetrahydrocortisol + 5-allotetrahydrocortisol/tetrahydrocortisone (THF + 5alphaTHF)/THE) ratio in the urine as an index of 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2) activity were analysed.

RESULTS

In offspring of DN+ patients on a high salt diet, systolic and diastolic BP was 137/82+/-10/8 mmHg vs 125/77+/-12/8 mmHg in offspring of DN- patients (P<0.01 for systolic BP). The salt-induced difference in mean BP between high and low salt diet was 5.2+/-3.3 mmHg in offspring of DN+ patients vs 0.7+/-4.7 mmHg in offspring of DN- patients (P<0.002). The proportion of 'salt-sensitive' individuals was 67% in offspring of DN+ patients vs 20% in offspring of DN- patients (P<0.05). In all groups, a high salt diet caused a comparable decrease of PRA and p-aldosterone accompanied by an increase in ANP. The urinary (THF + 5alphaTHF)/THE ratio was 1.23+/-0.36 in salt-sensitive individuals and 0.99+/-0.33 (P<0.03) in salt-resistant subjects, consistent with increased activity of 11betaHSD2.

CONCLUSIONS

BP is more salt sensitive in offspring of type 2 diabetic patients with diabetic nephropathy. The salt sensitivity of BP may be an intermediate phenotype in individuals with a high risk of future diabetic nephropathy.

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.

Effects of leptin and dexamethasone on long and short leptin receptor mRNA

BACKGROUND

Leptin exerts its effects by using both long (OB-Rb) and short (OB-Ra) receptors. Although leptin resistance or insensitivity is reported to be a cause of human obesity, there have not been enough studies to clarify regulation of leptin receptors.

METHODS

The authors studied leptin receptor regulation by leptin and dexamethasone in the human hepatocellular carcinoma cell (HepG2). Using a quantitative RT-PCR technique, the authors demonstrate expression of OB-Ra and OB-Rb mRNA after the incubation for 24 h with leptin or dexamethasone at various concentrations (10(-9)-10(-6) M).

RESULTS

Leptin (10(-7)-10(-6) M) significantly inhibited expression of OB-Rb mRNA, with maximum inhibition (43% of control) at 10(-6) M. Expression of OB-R219.1 and OB-R219.3, two short isoforms of leptin receptor, were also reduced in cells treated with leptin most remarkably at 10(-7) M for OB-R219.1 (44% of the control) and at 10(-6) M for Ob-R219.3 (49% of the control). In contrast, dexamethasone (10(-8)-10(-6) M) significantly increased OB-Rb mRNA levels, with a maximum increase (204% of the control) at 10(-7) M, and OB-R219.1 and OB-R219.3 mRNA expression was also markedly increased at 10(-9)-10(-6) M. The peak values were 254% of the control for OB-R219.1 and 246% of the control for OB-R219.3 at 10(-7) M.

CONCLUSIONS

In HepG2 cells, leptin inhibits and dexamethasone increases OB-Ra and OB-Rb mRNA expression. It is suggested that glucocorticoids as well as leptin itself contribute to regulatory effects of leptin through changes in gene expression of leptin receptors.

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.

Repeated Streptozotocin Injections Cause Early Onset of Glomerulosclerosis in Mice

Diabetic nephropathy (DN), a major cause of end-stage chronic renal failure, is histologically characterized by glomerulosclerosis. To investigate the molecular mechanisms of DN, it is important to establish a stable model of glomerulosclerosis in mice, because genomic manipulation techniques (such as gene destruction or transgene insertion) are well established in rodent species. In this study, we found that repeated administrations of streptozotocin led to early onset of glomerular sclerotic lesions in C57BL/6 mice, accompanied with renal dysfunction. During the natural course of DN, glomerular endothelial cells decreased at 10 weeks after the start of streptozotocin-injections, whereas myofibroblastic mesangial cells became evident. Our results provide an animal tool to elucidate the molecular mechanisms of DN, for example to investigate vascular pathology in diabetic glomerular diseases.

Effects of eplerenone, enalapril, and eplerenone/enalapril in patients with essential hypertension and left ventricular hypertrophy: the 4E-left ventricular hypertrophy study

BACKGROUND

Elevated renin-angiotensin-aldosterone system activity correlates with left ventricular hypertrophy (LVH) and cardiovascular risk, but the relative contributions of angiotensin II and aldosterone remain unclear. This study compared LVH regression during treatment with the selective aldosterone blocker eplerenone, enalapril, and their combination in patients with hypertension.

METHODS AND RESULTS

A 9-month, double-blind, randomized study was performed in 202 patients with LVH and hypertension who received eplerenone 200 mg daily, enalapril 40 mg daily, or eplerenone 200 mg and enalapril 10 mg daily. At week 8, hydrochlorothiazide 12.5 to 25 mg and/or amlodipine 10 mg was added if diastolic blood pressure was >90 mm Hg. Change in left ventricular (LV) mass as assessed by MRI was the primary end point. Change in blood pressure, renin-angiotensin-aldosterone system hormones, albuminuria, and safety were also assessed. Eplerenone significantly reduced LV mass from baseline (-14.5+/-3.36 g; n=50) similarly to enalapril (-19.7+/-3.20 g; n=54; P=0.258), but eplerenone/enalapril (-27.2+/-3.39 g; n=49) was more effective than eplerenone alone (P=0.007). All treatments reduced systolic blood pressure and diastolic blood pressure from baseline (eplerenone, -23.8 and -11.9 mm Hg; enalapril, -24.7 and -13.4 mm Hg; and eplerenone/enalapril, -28.7 and -14.4 mm Hg, P=0.048, in systolic blood pressure compared with eplerenone alone). Cough was more common with enalapril than with eplerenone (P=0.033), and elevated potassium was more common with eplerenone.

CONCLUSIONS

Eplerenone was as effective as enalapril in LVH regression and blood pressure control. The combination of eplerenone and enalapril was more effective in reducing LV mass and systolic blood pressure than eplerenone alone.

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.

Effectiveness of aldosterone blockade in patients with diabetic nephropathy

It has been reported that continuous ACE inhibitor therapy does not necessarily produce a maintained decrease in plasma aldosterone levels, which may remain high or increase eventually during long-term use (aldosterone escape). We have examined the role of aldosterone escape in 45 patients with type 2 diabetes and early nephropathy treated with an ACE inhibitor for 40 weeks. With treatment, there was a 40% reduction in average urinary albumin excretion, although urinary albumin excretion in patients with aldosterone escape (18 patients) was significantly higher than that in patients without escape (27 patients). In the 18 patients with escape, spironolactone (25 mg/d) was added to ACE inhibitor treatment in 13. After a 24-week study period, urinary albumin excretion and left ventricular mass index were significantly reduced without blood pressure change. In conclusion, the present study demonstrates that aldosterone escape is observed in 40% of patients with type 2 diabetes with early nephropathy despite the use of ACE inhibitors. Our study suggests the possibility that aldosterone blockade may represent optimal therapy for patients with early diabetic nephropathy who show aldosterone escape during ACE inhibitor treatment and who no longer show maximal antiproteinuric effects of ACE inhibition. Additional, larger, prospectively randomized, double-blind studies will be needed before adaptation of this strategy.