Aldosterone impairs insulin responsiveness in U-937 human promonocytic cells via the downregulation of its own receptor

In an earlier study, we have reported an inhibition of insulin receptor (IR) mRNA levels and insulin binding by aldosterone in U-937 human promonocytic cells. In the present extension of our studies, we demonstrate that this inhibition by aldosterone had no effects on basal glucose transport or on basal thymidine incorporation into DNA, while the cell responsiveness reflected by the maximal response to insulin was decreased by 23% for glucose transport and by 31% for DNA synthesis after the aldosterone treatment. We also prove that this inhibition of the insulin response by aldosterone is mediated by a downregulation of the levels of mineralocorticoid receptors (MRs) (50% decrease) and their mRNA (50% decrease). In addition, the mineralocorticoid antagonist spironolactone reversed the decrease in MR mRNA levels elicited by aldosterone, which suggests the involvement of this receptor in the process.     

醛固酮对心室成纤维细胞分泌内皮素的影响

用细胞培养、内皮素放射免疫测定和RT-PCR的方法,探讨醛固酮对心室成纤维细胞分泌内皮素的影响。结果显示,醛固酮(1×10     

血管紧张素转换酶抑制剂和醛固酮受体阻断剂对钙超载大鼠心功能的影响

目的:观察血管紧张素转换酶抑制剂(ACEI)和醛固酮(ALDO)受体阻断剂(spironolactone,安体舒通)对钙超载大鼠心功能的影响,以探讨钙超载引起心功能降低和心肌损伤的机制。方法:维生素D3加尼古丁诱导心肌钙超载,放射免疫法测定心肌组织AngⅡ和ALDO含量,Powerlab仪测定心功能,原子吸收测定心肌和血管钙含量,生化法测定心肌MDA和conjugated diene变化,自动生化分析仪测定血浆LDH和CPK含量。结果:心肌钙超载后,心肌和血管钙含量较对照组分别增加3.2和5.8倍,LVdp/dtmax和LVdp/dtmin分别降低27%和34%,LVESP和LVEDP增加42%和32%;心肌MDA和conjugated diene增加22%和68%;血浆LDH和CPK增加4.5和3.1倍(均P<0.01)。运用ACEI和ALDO受体阻断剂可缓解上述指标变化,与钙超载组相比,心肌钙含量分别低44%和39%,主动脉钙含量也低57%和34%,MDA低20%和30%,conjugated diene低44%和35%,LDH、CPK分别减少28%和34%、20%和27%(均P<0.01)。结论:心肌钙超载可以导致心功能下降和心肌损伤,运用ACEI和ALDO受体阻断剂可以减轻心肌钙超载和改善心功能,心肌损伤程度减轻。     

Rapid effects of aldosterone in primary cultures of cardiomyocytes – do they suggest the existence of a membrane-bound receptor?

Aldosterone acts on its target tissue through a classical mechanism or through the rapid pathway through a putative membrane-bound receptor. Our goal here was to better understand the molecular and biochemical rapid mechanisms responsible for aldosterone-induced cardiomyocyte hypertrophy. We have evaluated the hypertrophic process through the levels of ANP, which was confirmed by the analysis of the superficial area of cardiomyocytes. Aldosterone increased the levels of ANP and the cellular area of the cardiomyocytes; spironolactone reduced the aldosterone-increased ANP level and cellular area of cardiomyocytes. Aldosterone or spironolactone alone did not increase the level of cyclic 3',5'-adenosine monophosphate (cAMP), but aldosterone plus spironolactone led to increased cAMP level; the treatment with aldosterone?+?spironolactone?+?BAPTA-AM reduced the levels of cAMP. These data suggest that aldosterone-induced cAMP increase is independent of mineralocorticoid receptor (MR) and dependent on Ca²⁺. Next, we have evaluated the role of A-kinase anchor proteins (AKAP) in the aldosterone-induced hypertrophic response. We have found that St-Ht31 (AKAP inhibitor) reduced the increased level of ANP which was induced by aldosterone; in addition, we have found an increase on protein kinase C (PKC) and extracellular signal-regulated kinase 5 (ERK5) activity when cells were treated with aldosterone alone, spironolactone alone and with a combination of both. Our data suggest that PKC could be responsible for ERK5 aldosterone-induced phosphorylation. Our study suggests that the aldosterone through its rapid effects promotes a hypertrophic response in cardiomyocytes that is controlled by an AKAP, being dependent on ERK5 and PKC, but not on cAMP/cAMP-dependent protein kinase signaling pathways. Lastly, we provide evidence that the targeting of AKAPs could be relevant in patients with aldosterone-induced cardiac hypertrophy and heart failure.     

The suitability of disintegrating force kinetics for studying the effect of manufacturing parameters on spironolactone tablet properties

The aim of this paper was to study the effect of the granulate properties and tablet compression force on disintegrating force behavior in order to investigate the capability of the disintegrating force to characterize tablets that have the same composition but were manufactured in different conditions. Several tablets containing spironolactone in the external or internal granulated mixture of calcium carbonate and maize starch differing in particle size distribution, were prepared at 3 compression levels. The force developed by tablets during water uptake and disintegration was measured and plotted versus time. The curves obtained were analyzed by the Weibull equation in order to calculate the parameters characterizing the tablet disintegration kinetics. The disintegrating force time parameter, the maximum force developed, and the area under the curve were determined. In general, the reduction of time parameter value and/or the increase in maximum force developed corresponded to an acceleration in tablet disintegration. In addition, the area under the force curve increased in stronger tablets, monitoring in a sensitive way the tablet structural changes introduced by compression force. The results showed that the disintegrating force measurement can detect small changes in the structure of the tablet that cannot be discriminated by pharmacopoeia tests. The effect of manufacturing, in particular compression force, on tablet properties was quantified by the parameters of disintegrating force kinetics.     

Androgen and estrogen stimulation of ornithine decarboxylase activity in mouse kidney

In the present work, the activity of mouse renal ornithine decarboxylase (ODC) from CBA female mice was used as a biological marker to detect (anti)androgenic activity of different groups of endocrine disruptors and steroids. Daily injections of testosterone or dihydrotestosterone (DHT) into 60 day old female mice for 4 days increased renal ODC activity in a dose-dependent manner that reached up to 100-fold (testosterone) or 250-fold (DHT) above the baseline when the highest dose, 200 microg/mouse, was used. Administration of flutamide concurrently with testosterone (75 microg/mouse) caused a potent decrease of ODC induction in a dose-dependent manner, suppressing the enzyme activity at the doses of 0.1 and 0.5 mg/mouse by about 88 and 95%, respectively. In contrast, estradiol at the doses of 0.5 and 1 mg/mouse induced a significant stimulation of renal ODC activity in a dose-dependent manner when it was given alone or in combination with testosterone. Using a sensitive increase in ODC activity in response to androgens as an end point, we did not detect an antiandrogenic effect of several antiandrogens, such as cyproterone acetate, spironolactone, p,p'DDE and vinclozolin. Also, none of these antiandrogens were able to change the basal level of renal ODC activity, with the exception of cyproterone acetate that at a dose of 0.1 mg/mouse stimulated ODC activity. The data obtained suggest that mouse renal ODC from CBA females is not strictly androgen-specific and cannot be used for estimation of antiandrogenic effects of compounds having an affinity to different types of receptors.     

Inhibition of tissue repair by spironolactone: Role of mineralocorticoids in fibrous tissue formation

Mineralocorticoids have been implicated in promoting fibrous tissue formation in various organs. In the present study, we sought to address the potential contribution of mineralocorticoids to fibrous tissue formation using a skin pouch model which has proved valuable for the analysis of inflammatory and wound healing responses. Skin pouches were induced in rats by administration of a phorbol ester, croton oil (0.5 ml of a 1% solution). After 2 weeks, rats were killed and intact pouch tissue collected. Pouch weights of control and aldosterone-treated (0.75 g/h via osmotic minipump) rats were similar (3.33 ± 0.44 g vs. 3.70 ± 0.28 g respectively). However, pouch weights were reduced by more than 50% in spironolactone-treated (25 mg/day powdered in food) animals (1.62 ± 0.22 g and 1.27 ± 0.23 g respectively in aldosterone and spironolactone alone groups). To ascertain the effects of different treatments on collagen accumulation, hydroxyproline concentration was measured. Compared with controls, hydroxyproline concentration was significantly reduced following spironolactone treatment (17.1 ± 0.08 vs. 7.5 ± 2.0 g/mg dry wt, respectively, p < 0.01). This response to spironolactone was negated by coadministration of aldosterone (hydroxyproline concentration was 18.6 ± 2.1 g/mg dry wt). Following bilateral adrenalectomy, spironolactone reduced pouch weight and hydroxyproline concentration, which was not the case for adrenalectomy alone. Two week aldosterone administration in uninephrectomized rats on high salt diet was deemed ineffective in modulating pouch development (pouch wet wts were 3.48 ± 0.4 g vs. 3.00 ± 0.19 g in controls and aldosterone-treated rats, respectively). Mineralocorticoid receptor expression in pouch tissue was demonstrated by RT/PCR. Furthermore, NADP+-dependent 11-hydroxysteroid dehydrogenase 1 (11-HSD1) activity was detected in pouch tissue, together with lower levels of NAD+-dependent 11-HSD2. Spironolactone (p < 0.05) significantly reduced 11-HSD1 activity compared with controls. Thus, fibrous tissue possesses requisite components of MC action, and antagonism of mineralocorticoid receptors by spironolactone attenuates its formation. Pouch formation is under the influence of circulating MC and, we would like to propose, is also mediated through corticosteroids generated de novo at the site of tissue repair.     

Differences in selected zinc metabolism parameters in obese and normal-weight hypertensive patients following treatment with spironolactone

Twenty-three hypertensive outpatients aged 18–53 yr (average: 39.8±10.4 yr) were classified into two groups according to body mass index (BMI). Six patients exceeded the BMI limit, set at 30 kg/m². All were treated with 100 mg/d spironolactone and were subject to before and after measurements of their arterial pressure, efflux rate constants of zinc from lymphocytes (total ERCt-Zn and ouabain-dependent ERCos-Zn), serum zinc (Zn-s), lymphocyte zinc (Zn-l), serum aldosterone (Ald-s), plasma renin activity (PRA), serum sodium (Na-s), and potassium (K-s). After 7 d of spironolactone treatment, the ERCt-Zn change in normal-weight patients was +0.78±0.57, and −0.22±0.69 in obese patients. In the same manner, the change of ERCos-Zn was +0.59±0.94 and −0.025±0.32 in normal and obese patients, respectively. Serum Zn was increased in normal-weight patients but remained unchanged in the obese. The initial lymphocyte zinc values were significantly lower in obese patients, but increased up to normal values after spironolactone treatment.     

脑舒通胶囊对阿尔茨海默病患者外周血中IL-6 和TNF-α 水平的影响

目的:探讨脑舒通胶囊对阿尔茨海默病患者外周血中IL-6和TNF-α水平的影响,并观察脑舒通的临床疗效。方法:按年龄和病程将临床条件基本相同的患者随机分为两组:对照组15例;观察组(氯沙坦)22例。ELISA检测血清IL-6和TNF-α的含量。采用的量表为MMSE、ADL、Pfeffer功能活动调查表(POD),Fuld物体记忆测验(FOM),快速词汇测验(RVR)评定临床疗效,在入组时、治疗后第12周后评出。结果:对照组患者治疗前外周血中IL-6为(310±34)ng/ml,治疗后外周血中IL-6为(270±21)ng/ml,治疗前后比较无明显差异(P>0.05)。观察组患者治疗前外周血中IL-6为(321±38)ng/ml,治疗后外周血中IL-6为(185±19)ng/ml,治疗前后比较有统计学意义(P<0.05)。对照组患者治疗前外周血中TNF-α为(150±27)ng/ml,治疗后外周血中TNF-α为(135±21)ng/ml,治疗前后比较无明显差异(P>0.05)。观察组患者治疗前外周血中TNF-α为(154±25)ng/ml,治疗后外周血中TNF-α为(97±14)ng/ml,治疗前后比较有统计学意义(P<0.05)。观察组与对照组相比,前者外周血中TNF-α的含量明显降低。使用常规药物的对照组患者治疗前后MMSE、ADL、POD、FOM及RVR均无明显变化,而使用脑舒通胶囊的观察组患者治疗前后其MMSE、ADL、POD、FOM及RVR变化明显。结论:脑舒通可抑AD患者外周血中炎症因子的表达,且产生了较好的临床效果。     

Plasma concentrations of matrix metalloproteinase-2, tissue inhibitor of metalloproteinase-1 and osteopontin reflect severity of heart failure in DOCA-salt hypertensive rat

The matrix metalloproteinases (MMPs) and their endogenous inhibitors, the tissue inhibitors of metalloproteinases (TIMPs) play a key role in extracellular matrix maintenance and are altered in the failing heart, both in experimental models and in chronic end-stage heart failure in humans. As the common diagnostic markers of heart failure, atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) primarily reflect increased pressure loading, determination of soluble, heart-derived MMPs and TIMPs in plasma, as well as the determination of the emerging fibrosis marker osteopontin (OPN) might be valuable tools for detecting heart fibrosis. In this study the effect of spironolactone treatment on plasma MMP-2, TIMP-1 and OPN levels was assessed in a heart failure animal model. Unilaterally nephrectomized Sprague Dawley rats received subcutaneous injection of 100 mg deoxycorticosterone acetate (DOCA) once a week and 1% (w/v) NaCl in drinking water. Blood pressure was monitored weekly and blood samples were collected after 1, 2 and 4 weeks. After 6 weeks, left ventricular contractility (LVC) and heart weight-to-body weight ratio (HW/BW) were assessed. DOCA treatment increased plasma MMP-2, TIMP-1 and OPN concentrations. Alterations of plasma marker levels were correlated with changes of HW/BW and paralleled impaired LVC. Furthermore, beneficial effects of spironolactone treatment were observed. In DOCA-salt hypertensive rats, plasma concentrations of MMP-2, TIMP-1 and OPN reflected heart failure associated with haemodynamic, functional and morphological changes. Based on these findings, it appears reasonable to use plasma markers of fibrosis to monitor the development of heart failure.