Investigation Into the Cardiac Effects of Spironolactone in the Experimental Model of Type 1 Diabetes

Artemisinin attenuates type 2 diabetic cardiomyopathy in rats through modulation of AGE-RAGE/HMGB-1 signaling pathway

Diabetes mellitus is a common metabolic disorder. About two-thirds of diabetic patients develop diabetic cardiomyopathy (DCM), which becomes a challenging issue as it severely threatens the patient's life. Hyperglycemia and the resulting advanced glycated end products (AGE) and their receptor (RAGE)/High Mobility Group Box-1 (HMGB-1) molecular pathway are thought to be key players. Recently, artemisinin (ART) has gained more attention owing to its potent biological activities beyond its antimalarial effect. Herein, we aim to evaluate the effect of ART on DCM and the possible underlying mechanisms. Twenty-four male Sprague-Dawley rats were divided into: control, ART, type 2 diabetic and type 2 diabetic treated with ART groups. At the end of the research, the ECG was recorded, then the heart weight to body weight (HW/BW) ratio, fasting blood glucose, serum insulin and HOMA-IR were evaluated. Cardiac biomarkers (CK-MB and LDH), oxidative stress markers, IL-1β, AGE, RAGE and HMGB-1 expression were also measured. The heart specimens were stained for H&E as well as Masson's trichrome. DCM induced disturbances in all studied parameters; contrary to this, ART improved these insults. Our study concluded that ART could improve DCM through modulation of the AGE-RAGE/HMGB-1 signaling pathway, with subsequent impacts on oxidative stress, inflammation and fibrosis. ART could therefore be a promising therapy for the management of DCM.

Evaluation of selected antidiabetics in cardiovascular complications associated with cancer cachexia

So far, the cardio-protective potential of antidiabetics is proved, but their effect on cardiovascular complications associated with cancer cachexia is not explored until now. Insulin resistance and glucose intolerance along with systemic inflammation are prominent in cachexia but the potential effect of antidiabetic agents especially those belonging to biguanide, DPP4 inhibitors and SGLT2 on the heart are not studied till now. In present study, the effect of metformin, vildagliptin, teneligliptin, dapagliflozin and empagliflozin on cardiovascular complications associated with cancer cachexia by using B16F1 induced metastatic cancer cachexia and urethane-induced cancer cachexia was studied. These antidiabetic agents proved to be beneficial against cachexia-induced atrophy of the heart, preserved ventricular weights, maintained cardiac hypertrophic index, preserved the wasting of cardiac muscles assessed by HE staining, Masson trichrome staining, periodic acid Schiff staining and picro-Sirius red staining. Altered cardiac gene expression was attenuated after treatment with selected antidiabetics, thus preventing cardiac atrophy. Also, antidiabetic agents treatment improved the serum creatinine kinase MB, Sodium potassium ATPase and collagen in the heart. Reduction in blood pressure and heart rate was observed after treatment with antidiabetic agents. Results of our study show that the selected antidiabetics prove to be beneficial in attenuating the cardiac atrophy and helps in regulation of hemodynamic stauts in cancer cachexia-induced cardiovascular complications. Our study provides some direction towards use of selected antidiabetic agents in the management of cardiovascular complications associated with cancer cachexia and the study outcomes can be useful in desiging clinical trials.

Systemic study of selected histone deacetylase inhibitors in cardiac complications associated with cancer cachexia

Cancer cachexia is mainly characterized by wasting of skeletal muscles and fat and body weight loss, along with severe complications of major organs like liver, heart, brain and bone. There can be diminishing performance of these major organs as cancer cachexia progresses, one such drastic effect on the cardiac system. In the present study, differential effect of histone deacetylase inhibitors (HDACi) on cardiac complications associated with cancer cachexia is studied. Two models were used to induce cancer cachexia: B16F1 induced metastatic cancer cachexia and Lewis lung carcinoma cell - induced cancer cachexia. Potential of Class I HDACi entinostat, Class II HDACi MC1568, and nonspecific HDACi sodium butyrate on cardiac complications were evaluated using the cardiac hypertrophy markers, hemodynamic markers, and cardiac markers along with histopathological evaluation of heart sections by Periodic acid-Schiff staining, Masson's trichrome staining, Picro-sirius red staining, and haematoxylin and eosin staining. Immunohistochemistry evaluation by vimentin and caspase 3 protein expression was evaluated. Entinostat showed promising results by attenuating the cardiac complications, and MC1568 treatment further exacerbated the cardiac complications, while non-conclusive effect were recorded after treatment with sodium butyrate. This study will be helpful in evaluating other HDACi for potential in cardiac complications associated with cancer cachexia.

Cardiac Complications: The Understudied Aspect of Cancer Cachexia

The global burden of cancer cachexia is increasing along with drastic increase in cancer patients. Cancer itself leads to cachexia, and cachexia development is associated with events like altered hemodynamics, and reduced functional capacity of the heart among others which lead to failure of the heart and are called cardiovascular complications associated with cancer cachexia. In some patients, the anti-cancer therapy also leads to this cardiovascular complications. So, in this review, an attempt is made to understand the mechanisms, pathophysiology of cardiovascular events in cachectic patients. Important processes which cause cardiovascular complications include alterations in the structure of the heart, loss of cardiac mass and functioning, cardiac fibrosis and cardiac remodeling, apoptosis, cardiac muscle atrophy, and mitochondrial alterations. Previously, the available treatment options were limited to nutraceuticals and physical exercise. Recently, studies with some prospective agents that can improve cardiac health have been reported, but whether their action is effective in cardiovascular complications associated with cancer cachexia is not known or are under trial.

NRF2 in Cardiovascular Diseases: a Ray of Hope!

Heart failure is a worldwide pandemic influencing 26 million individuals worldwide and is expanding. Imbalanced redox homeostasis in cardiac cells alters the structure and function of the cells, which leads to contractile dysfunction, myocardial hypertrophy, and fibrosis in chronic heart failure. Various targets and agents acting on these such as siRNA, miRNA, interleukin-1, opioids, vasodilators, and SGLT2 inhibitors are being evaluated for heart failure, and nuclear factor erythroid 2-related factor 2 (NRF2) is one of them. NRF2 is a master transcription factor which is expressed in most of the tissues and exhibits a major role in amplification of the antioxidant pathways associated with the enzymes present in myocardium. Increased ROS generation and PI3K-Akt signaling can activate the receptor NRF2. Various in vitro and in vivo and few clinical studies suggested NRF2 may possess a potential for targeting oxidative stress-induced cardiovascular diseases including heart failures. All these studies collectively propose that upregulation of NRF2 will attenuate the increase in hemodynamic stress and provide beneficial role in cardiovascular diseases. The current review shall familiarize readers about the regulations and functions of NRF2. We have also discussed the current evidences suggesting beneficial role of NRF2 activators in heart failure. Graphical abstract.

Inducible Nitric Oxide Synthase and L-Arginine Optimizes Nitric Oxide Bioavailability in Ischemic Tissues Under Diabetes Mellitus Type 1

BACKGROUND

The mechanisms influencing the balance of nitric oxide (NO) bioavailability in tissues are negatively affected under diabetic and also under ischemic conditions. Free tissue transplantation for diabetic patients has to deal with both ischemic and diabetic circumstances, which lead to a significantly decrease in providing NO, thus increasing ischemia-reperfusion injury. In previous studies, we could prove that enhancing NO bioavailability leads to attenuated ischemia-reperfusion injury macrocirculatory and microcirculatory alterations in healthy and also in diabetes type 2 rats. This study is evaluating the role of inducible nitric oxide synthase in different dosages and L-arginine under diabetes type 1 conditions.

METHODS

Diabetic type 1 conditions were established via streptozotocin over a period of 4 weeks and verified via blood sugar, insulin, and C-peptide levels. Vascular pedicle isolated rat skin flap model that underwent 3 hours of ischemia was used. At 30 minutes before ischemia, normal saline, inducible nitric oxide synthase (NOS) (1/2 IE), and L-arginine (50 mg/kg body weight) were administered systemically. Ischemia/reperfusion (I/R)-induced alterations were measured 5 days after the operation.

RESULTS

The inducible NOS (iNOS) attenuated I/R-induced alterations under diabetic type 1 conditions significantly with vitality rates of 16.1% compared with control group (5.5%). Best results could be achieved with the combination of iNOS (1 IE) and L-arginine displaying vitality rates of 43%. Increased dosage of inducible nitric oxide (2 IE) led to decreased vitality rates (22.2%/27.4% without/with L-arginine).

CONCLUSIONS

Supporting the mechanisms of NO bioavailability via exogenous application of iNOS and L-arginine significantly attenuated I/R-induced alterations in a skin flap rat model. This pharmacologic preconditioning could be an easy and effective interventional strategy to uphold conversation of L-arginine to NO even on ischemic and type 1 diabetic conditions.

Repurposing of sodium valproate in colon cancer associated with diabetes mellitus: Role of HDAC inhibition

BACKGROUND AND PURPOSE

Diabetic patients are at greater risk for colon cancer. Histone deacetylases (HDACs) serve as common target for both. The key objective of the study was to evaluate the effect of sodium valproate in type 2 diabetes mellitus associated colon cancer.

EXPERIMENTAL APPROACH

High fat diet and streptozotocin were used to induce type 2 diabetes. Following this, after diabetes confirmation, colon cancer was induced using 1,2 dimethylhydrazine (25 mg/kg, s.c.) once weekly from 7th week to 20th weeks. Sodium valproate (200 mg/kg) treatment was given from 20th to 24th week. At the end of 24 weeks, several enzymatic and biochemical parameters, were estimated. MTT, clonogenic and scratch wound healing assay were carried out in HCT-15 cell line.

KEY RESULTS

Hyperglycemia, hyperinsulinemia, increase in cytokines (TNF-α and IL-1β) and carcinoembryonic antigen and presence of proliferating cells was seen in disease control animals which was prevented by sodium valproate treatment. Overexpression of relative HDAC2 mRNA levels was found in diseased control animals, which was reduced by sodium valproate treatment. IC₅₀ of sodium valproate was found to be 3.40 mM and 3.73 mM at 48 h and 72 h respectively on HCT-15 cell line. Sodium valproate also dose dependently prevented colony formation and cell migration.

CONCLUSION AND IMPLICATIONS

Sodium valproate can be considered for repurposing in colon cancer associated with diabetes mellitus.

Magnesium valproate ameliorates type 1 diabetes and cardiomyopathy in diabetic rats through estrogen receptors

Estrogen is known to exhibit cardioprotective and antihyperlipidemic action. Valproic acid has been shown to upregulate estrogen receptors (ERs) in breast and prostate cancer tissues. No pharmacological evaluations for magnesium valproate (MgV) so far have been done for diabetic cadio-lipidemic complications. Based on the above context, current study was undertaken to evaluate the therapeutic effectiveness of MgV in cardiac complications associated with type-1 diabetes mellitus in rats wherein diabetes was induced by single tail vein injection of streptozotocin (STZ, 45mg/kg, IV) in female Sprague Dawley rats and treatment of MgV (210mg/kg, PO) was given for eight weeks to diabetic animals, after which, various biochemical and cardiac biomarkers, hypertrophic, hemodynamic and histological parameters along with immunohistochemistry of ERs in the left ventricle (LV) were estimated. MgV treatment significantly controlled hyperglycemia and dyslipidemia, reduced elevated cardiac biomarkers and C-reactive protein(CRP), significantly improved hemodynamic functions and increased the rate of pressure development and decay. MgV also significantly reduced left ventricular hypertrophy index and cardiac hypertrophy index, LV wall thickness, LV collagen, cardiomyocyte diameter and prevented the oxidative stress with significant increase in Na⁺-K⁺-ATPase activity in LV. Moreover, MgV reversed STZ-induced histological alterations and decreased glycogen content in LV and increased the ER_β expressions in LV as evidenced by immunohistochemistry. The result indicated that MgV prevented disease progression in the early stage of diabetic cardiomyopathy which seems to be mediated by upregulation of estrogen receptors in LV tissue.

Selective inhibition of HDAC2 by magnesium valproate attenuates cardiac hypertrophy

The regulatory paradigm in cardiac hypertrophy involves alterations in gene expression that is mediated by chromatin remodeling. Various data suggest that class I and class II histone deacetylases (HDACs) play opposing roles in the regulation of hypertrophic pathways. To address this, we tested the effect of magnesium valproate (MgV), an HDAC inhibitor with 5 times more potency on class I HDACs. Cardiac hypertrophy was induced by partial abdominal aortic constriction in Wistar rats, and at the end of 6 weeks, we evaluated hypertrophic, hemodynamic, and oxidative stress parameters, and mitochondrial DNA concentration. Treatment with MgV prevented cardiac hypertrophy, improved hemodynamic functions, prevented oxidative stress, and increased mitochondrial DNA concentration. MgV treatment also increased the survival rate of the animals as depicted by the Kaplan-Meier curve. Improvement in hypertrophy due to HDAC inhibition was further confirmed by HDAC mRNA expression studies, which revealed that MgV decreases expression of pro-hypertrophic HDAC (i.e., HDAC2) without altering the expression of anti-hypertrophic HDAC5. Selective class I HDAC inhibition is required for controlling cardiac hypertrophy. Newer HDAC inhibitors that are class I inhibitors and class II promoters can be designed to obtain "pan" or "dual" natural HDAC "regulators".

An evaluation of the protective role of Ficus racemosa Linn. in streptozotocin-induced diabetic neuropathy with neurodegeneration

Objective:

Ficus racemosa (FR) is one of the herbs mentioned in the scriptures of the Ayurveda as Udumbara with high medicinal value. The objective of this study was to estimate the protective effect of FR against streptozotocin (STZ) induced diabetic neuropathy with neurodegeneration (DNN).

Materials and Methods:

Diabetes was induced in Wistar rats with STZ and were divided into six groups namely diabetic vehicle control, FR (four) and glibenclamide (one) treated rats; while one group was of normal control rats. After the 4^th week of diabetes, induction treatment was started for further 28 days (5^th to 8^th week) with FR aqueous extract (250 mg/kg and 500 mg/kg) and ethanolic extract (200 mg/kg and 400 mg/kg). Investigation of DNN was carried out through biochemical and behavioral parameter assessment in rats.

Results:

Study showed a significant fall in glycosylated hemoglobin (HbA1c) and blood glucose level by the treatment of FR in diabetic rats. Antioxidant potential of FR showed a great rise in superoxide dismutase, catalase content and reduction observed in serum nitrite level; while significant fall in lipid peroxidation level and of C-reactive protein was observed in FR treated diabetic rats. Further FR treated diabetic rats also showed marked improvement in tail flick latency, pain threshold, the rise in locomotion and fall latency period.

Conclusion:

Treatment with FR shows protection in the multiple pathways of DNN by improving blood glucose, HbA1c, biochemical, and behavioral parameters, which suggest the protective role of FR in the reversal of DNN.

Evaluation of role of telmisartan in combination with 5-fluorouracil in gastric cancer cachexia

BACKGROUND

The objective of the present study was to evaluate the effect of combination of telmisartan with 5-flourouracil (5-FU) in gastric cancer cachexia induced by administering N-methyl-N'-methyl-N-nitrosoguanidine (MNNG).

METHOD

MNND was administered once daily by oral gavage for two weeks, and saturated NaCl (1ml per rat) was then given once every 3days for 4weeks. 5-FU (75mg/kg, i.v.) was administered once three weeks from 7th to 22nd week. From 7th to 22nd week, telmisartan (5mg/kg, p.o.) was also administered along with 5-FU.

RESULT

MNNG produced significant decrease in food intake, body weight, caused hyperglycemia, dyslipidemia, hypertension worsened hemodyanamics, increased cachexia markers and increased tumor markers like lactate dehydrogenase and γ-glutamyltransferase. MNNG also produced oxidative stress in the stomach tissue. Treatment with combination of telmisartan with 5-FU produced significant increase in food intake and body weight, controlled hyperglycemia and dyslipidemia, preserved hemodynamic function, and decreased the cachexia markers while 5-FU alone did not produce any such effects. Further, the combination of telmisartan with 5-FU significantly reduced tumor marker levels, oxidative stress and also significantly decreased the cell proliferation, apoptosis, hyperkeratosis, keratohyaline granules and invasive carcinoma of forestomach and reduced muscle atrophy in tibilias anterior skeletal muscle.

CONCLUSION

Our data suggests that combination of telmisartan with 5-FU treatment is beneficial in controlling cancer cachexia. Telmisartan can be used as an add-on therapy with 5-FU or other traditional chemotherapeutic agents.

Effect of low-dose spironolactone on resistant hypertension in type 2 diabetes mellitus: a randomized controlled trial in a sub-Saharan African population

Background

Low-dose spironolactone has been proven to be effective for resistant hypertension in the general population, but this has yet to be confirmed in type 2 diabetic (T2DM) patients. We assessed the efficacy of a low-dose spironolactone on resistant hypertension in a sub-Saharan African population of T2DM patients from Cameroon.

Methods

This was a four-week single blinded randomized controlled trial in 17 subjects presenting with resistant hypertension in specialized diabetes care units in Cameroon. They were randomly assigned to treatment with a daily 25 mg of spironolactone (n = 9) or to an alternative antihypertensive regimen (n = 8), on top of any ongoing regimen and prevailing lifestyle prescriptions. They were seen at the start of the treatment, then 2 and 4 weeks later. The primary outcome was change in office and self-measured blood pressure (BP) during follow-up, and secondary outcomes were changes in serum potassium, sodium, and creatinine levels.

Results

Compared with alternative treatment, low-dose spironolactone was associated with significant decrease in office systolic BP (−33 vs. −14 mmHg; p = 0.024), and in diastolic BP (−14 vs. −5 mmHg; p = 0.006). After 1 month of spironolactone, all the patients were controlled based on BP below 130/80 mmHg, with significant office BP reduction from 158 ± 17/86 ± 11 to 125 ± 11/72 ± 8, vs. 158 ± 8/94 ± 8 to 144 ± 17/89 ± 12 mmHg in the alternative treatment group. There was no significant variation in sodium and creatinine levels in both groups, but a mild increase of potassium levels in the spironolactone group.

Interpretation

Add-on low-dose spironolactone was effective in reducing BP to optimal levels in T2DM Cameroonian patients despite mild increase in serum potassium.

Trial registration ClinicalTrials.gov Identifier NCT02426099. Date of registration April 2015

Chronic Rho-kinase inhibition improves left ventricular contractile dysfunction in early type-1 diabetes by increasing myosin cross-bridge extension

BACKGROUND

Impaired actin-myosin cross-bridge (CB) dynamics correlate with impaired left ventricular (LV) function in early diabetic cardiomyopathy (DCM). Elevated expression and activity of Rho kinase (ROCK) contributes to the development of DCM. ROCK targets several sarcomeric proteins including myosin light chain 2, myosin binding protein-C (MyBP-C), troponin I (TnI) and troponin T that all have important roles in regulating CB dynamics and contractility of the myocardium. Our aim was to examine if chronic ROCK inhibition prevents impaired CB dynamics and LV dysfunction in a rat model of early diabetes, and whether these changes are associated with changes in myofilament phosphorylation state.

METHODS

Seven days post-diabetes induction (65 mg/kg ip, streptozotocin), diabetic rats received the ROCK inhibitor, fasudil (10 mg/kg/day ip) or vehicle for 14 days. Rats underwent cardiac catheterization to assess LV function simultaneous with X-ray diffraction using synchrotron radiation to assess in situ CB dynamics.

RESULTS

Compared to controls, diabetic rats developed mild systolic and diastolic dysfunction, which was attenuated by fasudil. End-diastolic and systolic myosin proximity to actin filaments were significantly reduced in diabetic rats (P < 0.05). In all rats there was an inverse correlation between ROCK1 expression and the extension of myosin CB in diastole, with the lowest ROCK expression in control and fasudil-treated diabetic rats. In diabetic and fasudil-treated diabetic rats changes in relative phosphorylation of TnI and MyBP-C were not significant from controls.

CONCLUSIONS

Our results demonstrate a clear role for ROCK in the development of LV dysfunction and impaired CB dynamics in early DCM.

Beneficial role of tamoxifen in isoproterenol-induced myocardial infarction

ER-α and ER-β agonist 17β-estradiol is reported to attenuate cardiac hypertrophy. Tamoxifen is a selective estrogen receptor modulator. Hence, the objective of this study was to investigate the effects of tamoxifen in myocardial infarction. For this, tamoxifen was administered to Sprague–Dawley rats for 1–14 days, and isoproterenol (ISO) (100 mg·(kg body mass)−1·day−1) was administered subcutaneously on the 13th and 14th days of the study in order to induce myocardial infarction, after which, various biochemical, cardiac, and morphometric parameters were evaluated. ISO produced significant dyslipidemia, hypertension, bradycardia, oxidative stress, and an increase in serum cardiac markers. Treatment with tamoxifen significantly controlled dyslipidemia, hypertension, bradycardia, oxidative stress, and reduced serum cardiac markers. The ISO control rats exhibited significant increases in the infarct size of the left ventricle (LV), LV cavity area, cardiac and LV hypertrophic indices, LV-wall thickness, cardiomyocyte diameter, and area. Treatment with tamoxifen significantly reduced infarction as well as hypertrophic and morphometric parameters. ISO also produced significant increases in the LV collagen level, decreases in Na+K+ATPase activity, and a reduction in the rate of pressure development and decay, which were prevented by tamoxifen treatment. The protective effect of tamoxifen on myocardial infarct was further confirmed by histopathological examination. Our data thus suggest that tamoxifen exerts beneficial effects in ISO-induced myocardial infarction.

Combination of telmisartan with cisplatin controls oral cancer cachexia in rats

The objective of the present investigation was to study the effect of combination of telmisartan with cisplatin in oral cancer cachexia induced by applying 0.5% 4-nitroquinoline-1-oxide (4-NQO) in propylene glycol to tongue, thrice a week for 8 weeks. From 8th to 22nd week, cisplatin (0.23 mg/kg, i.v.) was administered once in three weeks and telmisartan (5 mg/kg/day, p.o.) was administered daily. 4-NQO produced significant decrease in food intake, body weight, hyperglycemia, dyslipidemia, hypertension, and bradycardia, worsened hemodyanamics, increased cachexia markers like insulin, C-reactive protein, and interleukin-6, and increased tumor markers like lactate dehydrogenase and γ-glutamyl transferase.Treatment with combination of telmisartan with cisplatin produced significant increase in food intake and body weight and controlled hyperglycaemia and dyslipidemia, preserved hemodynamic function, and decreased the cachexia markers while cisplatin alone did not produce any increase in food intake and body weight. Further, the combination of telmisartan with cisplatin significantly reduced tumor marker levels. Combination of telmisartan with cisplatin prevented 4-NQO induced oxidative stress, hyperplasia and hyperkeratosis, premalignant dysplasia, and invasive squamous cell carcinoma in the tongue. Our data suggests that combination of telmisartan with cisplatin treatment is beneficial in controlling cancer cachexia. Telmisartan can be used as an add-on therapy with cisplatin or other traditional chemotherapeutic agents.

Downregulation of the cardiotrophin-1 gene expression by valsartan and spironolactone in hypertrophied heart rats in vivo and rat cardiomyocyte H9c2 cell line in vitro: a novel mechanism of cardioprotection

The incidence, prevalence, and hospitalization rates associated with heart failure (HF) are projected to increase substantially in the world. Among all medications used clinically to treat HF, valsartan (VAL) and spironolactone (SPL) have been shown to reduce morbidity and mortality. Recently, a novel cardiac gene cardiotrophin-1 (CT-1) has been shown to play a crucial role in the pathogenesis of HF. However, the ability of VAL and SPL to modulate the expression of CT-1 has not been investigated yet. Therefore, healthy and isoproterenol (ISO)-induced hypertrophy adult male Wistar albino rats were treated with either VAL or SPL for 14 days. Thereafter, cardiac markers of cardiotoxicity and hypertrophy, creatine kinase, heart weight/body weight ratio, and atrial natriuretic peptide mRNA levels were measured. In addition, CT-1 mRNA and protein levels were determined by real-time polymerase chain reaction and Western blot analysis. Our results showed that the increases in all HF markers, creatine kinase, heart weight/body weight ratio, and atrial natriuretic peptide mRNA levels in ISO-treated rats were significantly restored to their normal levels by VAL and SPL. In addition, induction of cardiac hypertrophy by ISO caused remarkable induction in CT-1 mRNA and protein expression levels by approximately 3.5- and 3-fold, respectively. Importantly, VAL and SPL significantly decreased the induction of CT-1 gene at the mRNA and protein levels in heart hypertrophied rats. On the other hand, treatment of cardiac-derived rat myoblast H9c2 cells with VAL and SPL significantly decreased angiotensin II-induced CT-1 mRNA levels through transcriptional mechanism, as demonstrated by the effect of transcription inhibitor, actinomycin D. In conclusion, VAL and SPL exhibited their cardioprotective effect through inhibiting the expression of CT-1 gene in cardiac hypertrophied rats.

Aldosterone antagonists in monotherapy are protective against streptozotocin-induced diabetic nephropathy in rats

Angiotensin converting enzyme inhibitors (ACEi) and angiotensin II receptor blockers (ARB) are the standard clinical therapy of diabetic nephropathy (DN), while aldosterone antagonists are only used as adjuncts. Previously in experimental DN we showed that Na/K ATPase (NKA) is mislocated and angiotensin II leads to superimposed renal progression. Here we investigated the monotherapeutic effect of aldosterone blockers on the progression of DN and renal NKA alteration in comparison to ACEi and ARBs. Streptozotocin-diabetic rats developing DN were treated with aldosterone antagonists; ACEi and ARB. Renal function, morphology, protein level and tubular localization of NKA were analyzed. To evaluate the effect of high glucose per se; HK-2 proximal tubular cells were cultured in normal or high concentration of glucose and treated with the same agents. Aldosterone antagonists were the most effective in ameliorating functional and structural kidney damage and they normalized diabetes induced bradycardia and weight loss. Aldosterone blockers also prevented hyperglycemia and diabetes induced increase in NKA protein level and enzyme mislocation. A monotherapy with aldosterone antagonists might be as, or more effective than ACEi or ARBs in the prevention of STZ-induced DN. Furthermore the alteration of the NKA could represent a novel pathophysiological feature of DN and might serve as an additional target of aldosterone blockers.