Hypertension aggravates glomerular dysfunction with oxidative stress in a rat model of diabetic nephropathy

Nimbidiol protects from renal injury by alleviating redox imbalance in diabetic mice

Introduction

Chronic hyperglycemia-induced oxidative stress plays a crucial role in the development of diabetic nephropathy (DN). Moreover, adverse extracellular matrix (ECM) accumulation elevates renal resistive index leading to progressive worsening of the pathology in DN. Nimbidiol is an alpha-glucosidase inhibitor, isolated from the medicinal plant, 'neem' (Azadirachta indica) and reported as a promising anti-diabetic compound. Previously, a myriad of studies demonstrated an anti-oxidative property of a broad-spectrum neem-extracts in various diseases including diabetes. Our recent study has shown that Nimbidiol protects diabetic mice from fibrotic renal dysfunction in part by mitigating adverse ECM accumulation. However, the precise mechanism remains poorly understood.

Methods

The present study aimed to investigate whether Nimbidiol ameliorates renal injury by reducing oxidative stress in type-1 diabetes. To test the hypothesis, wild-type (C57BL/6J) and diabetic Akita (C57BL/6-Ins2Akita/J) mice aged 10-14 weeks were used to treat with saline or Nimbidiol (400 μg kg-1 day-1) for 8 weeks.

Results

Diabetic mice showed elevated blood pressure, increased renal resistive index, and decreased renal vasculature compared to wild-type control. In diabetic kidney, reactive oxygen species and the expression levels of 4HNE, p22phox, Nox4, and ROMO1 were increased while GSH: GSSG, and the expression levels of SOD-1, SOD-2, and catalase were decreased. Further, eNOS, ACE2, Sirt1 and IL-10 were found to be downregulated while iNOS and IL-17 were upregulated in diabetic kidney. The changes were accompanied by elevated expression of the renal injury markers viz., lipocalin-2 and KIM-1 in diabetic kidney. Moreover, an upregulation of p-NF-κB and a downregulation of IkBα were observed in diabetic kidney compared to the control. Nimbidiol ameliorated these pathological changes in diabetic mice.

Conclusion

Altogether, the data of our study suggest that oxidative stress largely contributes to the diabetic renal injury, and Nimbidiol mitigates redox imbalance and thereby protects kidney in part by inhibiting NF-κB signaling pathway in type-1 diabetes.

Renoprotective effect of GLP-1 receptor agonist, liraglutide, in early-phase diabetic kidney disease in spontaneously diabetic Torii fatty rats

BACKGROUND

The aim of this study is to investigate the renoprotective effect of the GLP-1 receptor agonist, liraglutide, in early-phase diabetic kidney disease (DKD) using an animal model of type 2 diabetes with several metabolic disorders.

METHODS

Male 8-week-old spontaneously diabetic Torii (SDT) fatty rats (n = 19) were randomly assigned to three groups. The liraglutide group (n = 6) was injected subcutaneously with liraglutide. Another treatment group (n = 6) received subcutaneous insulin against hyperglycemia and hydralazine against hypertension for matching blood glucose levels and blood pressure with the liraglutide group. The control groups of SDT fatty (n = 7) and non-diabetic Sprague-Dawley rats (n = 7) were injected only with a vehicle.

RESULTS

The control group of SDT fatty rats exhibited hyperglycemia, obesity, hypertension, hyperlipidemia, glomerular sclerosis, and tubulointerstitial injury with high urinary albumin and L-FABP levels. Liraglutide treatment reduced body weight, food intake, blood glucose and blood pressure levels, as well as ameliorated renal pathologic findings with lower urinary albumin and L-FABP levels. Liraglutide increased expressions of phosphorylated (p)-eNOS and p-AMPK in glomeruli, downregulated renal expression of p-mTOR, and increased renal expressions of LC3B-II, suggesting activation of autophagy. However, these effects were not caused by the treatments with insulin and hydralazine, despite comparable levels of hyperglycemia and hypertension to those achieved with liraglutide treatment.

CONCLUSIONS

Liraglutide may exert a renoprotective effect via prevention of glomerular endothelial abnormality and preservation of autophagy in early-phase DKD, independent of blood glucose, and blood pressure levels.

Urinary NGAL and RBP Are Biomarkers of Normoalbuminuric Renal Insufficiency in Type 2 Diabetes Mellitus

Objectives

As a screening index of diabetic kidney disease (DKD), urinary albumin/creatine ratio (UACR) is commonly used. However, approximately 23.3%-56.6% of DKD patients with estimated glomerular filtration rate (eGFR) < 60 ml/min per 1.73 m² are normoalbuminuric. Thus, urinary biomarkers of nonalbuminuric renal insufficiency in type 2 diabetes mellitus (T2DM) patients are urgently needed.

Methods

This cross-sectional study enrolled 209 T2DM patients with normoalbuminuria whose diabetes duration was more than 5 years. The patients were classified into two groups, NO-CKD (eGFR ≥ 60 ml/min per 1.73 m², n = 165) and NA-DKD (eGFR < 60 ml/min per 1.73 m², n = 44). Levels of urinary neutrophil gelatinase-associated lipocalin (NGAL), retinol-binding protein (RBP), plasminogen activator inhibitor-1 (PAI-1), vascular cell adhesion molecule-1 (VCAM-1), and E-cadherin were detected, and their correlations with eGFR, plasma TNF-α, IL-6, endothelin-1 (ET-1), and 8-hydroxydeoxyguanosine (8-OHdG) were assessed.

Results

Among patients with renal insufficiency, 26.0% was normoalbuminuric. Compared to the NO-CKD group, the NA-DKD group was older with lower hemoglobin (HB) levels and higher systolic blood pressure (SBP), plasma TNF-α, IL-6, and 8-OHdG levels. Logistic regression analysis suggested that age, TNF-α, and 8-OHdG were independent risk factors for nonalbuminuric renal insufficiency. Compared to the NO-CKD group, the NA-DKD group exhibited significant increases in urinary NGAL and RBP levels but not PAI-1, VCAM-1, and E-cadherin. Urinary NGAL and RBP both correlated negatively with eGFR and positively with plasma IL-6 and 8-OHdG. Multiple linear regression indicated NGAL (β = -0.287, p = 0.008) and RBP (β = -44.545, p < 0.001) were independently correlated with eGFR.

Conclusion

Age, plasma TNF-α, and 8-OHdG are independent risk factors for renal insufficiency in T2DM patients with normoalbuminuria. Urinary NGAL and RBP can serve as noninvasive biomarkers of normoalbuminuric renal insufficiency in T2DM.

Diabetes downregulates renal adenosine A2A receptors in an experimental model of hypertension

Studies on diabetic nephropathy rarely take into account that the co-existence of diabetes and hypertension is frequent and further aggravates the prognosis of renal dysfunction. Adenosine can activate four subtypes of adenosine receptors (A₁, A_2A, A_2B and A₃) and has been implicated in diabetic nephropathy. However, it is not known if, in hypertensive conditions, diabetes alters the presence/distribution profile of renal adenosine receptors. The aim of this work was to describe the presence/distribution profile of the four adenosine receptors in six renal structures (superficial/deep glomeruli, proximal/distal tubules, loop of Henle, collecting tubule) of the hypertensive kidney and to evaluate whether it is altered by diabetes. Immunoreactivities against the adenosine receptors were analyzed in six renal structures from spontaneously hypertensive rats (SHR, the control group) and from SHR rats with diabetes induced by streptozotocyin (SHR-STZ group). Data showed, for the first time, that all adenosine receptors were present in the kidney of SHR rats, although the distribution pattern was specific for each adenosine receptor subtype. Also, induction of diabetes in the SHR was associated with downregulation of adenosine A_2A receptors, which might be relevant for the development of hypertensive diabetic nephropathy. This study highlights the adenosine A_2A receptors as a potential target to explore to prevent and/or treat early diabetes-induced hyperfiltration, at least in hypertensive conditions.

Amelioration of Diabetes-Induced Diabetic Nephropathy by Aloe vera: Implication of Oxidative Stress and Hyperlipidemia

This study investigated the effect of Aloe vera in diabetes-induced nephropathy in rats. As diabetes-associated hyperlipidemia and oxidative stress have been implicated in the pathogenesis of diabetic nephropathy, we evaluated the protective effect of whole leaf extract of Aloe vera on the basis of its hypolipidemic and antioxidative property. Aloe vera (300 mg/kg orally) has been noted to possess renoprotective effect in experimental diabetic nephropathy. However, its mechanism is not fully understood. Rats were administered streptozotocin (STZ) (55 mg/kg intraperitoneally once) to induce experimental diabetes mellitus. The development of diabetic nephropathy was assessed biochemically and histologically. In addition, the diabetes-induced lipid profile and renal oxidative stress were assessed. The single administration of STZ produced diabetes, which induced renal oxidative stress, altered the lipid profile, and subsequently produced nephropathy in eight weeks by increasing serum creatinine, blood urea nitrogen, proteinuria, and glomerular damage. Treatment with Aloe vera (300 mg/kg/day orally) was noted to be more effective against the diabetes-induced nephropathy and renal oxidative stress as compared to lisinopril (1 mg/kg/day orally), a reference agent. It may be concluded that diabetes-induced oxidative stress and lipid alterations may be accountable for the induction of nephropathy in diabetic rats. The treatment with Aloe vera (300 mg/kg/day orally) may have prevented the development of diabetes-induced nephropathy by reducing lipid alteration, decreasing renal oxidative stress, and providing direct renoprotective action.

Nitric oxide production by glomerular podocytes

Nitric Oxide (NO), a potent vasodilator and vital signaling molecule, has been shown to contribute to the regulation of glomerular ultrafiltration. However, whether changes in NO occur in podocytes during the pathogenesis of salt-sensitive hypertension has not yet been thoroughly examined. We showed here that podocytes produce NO, and further hypothesized that hypertensive animals would exhibit reduced NO production in these cells in response to various paracrine factors, which might contribute to the damage of glomeruli filtration barrier and development of proteinuria. To test this, we isolated glomeruli from the kidneys of Dahl salt-sensitive (SS) rats fed a low salt (LS; 0.4% NaCl) or high salt (HS; 4% NaCl, 3 weeks) diets and loaded podocytes with either a combination of NO and Ca²⁺ fluorophores (DAF-FM and Fura Red, respectively) or DAF-FM alone. Changes in fluorescence were observed with confocal microscopy in response to adenosine triphosphate (ATP), angiotensin II (Ang II), and hydrogen peroxide (H₂O₂). Application of Ang II resulted in activation of both NO and intracellular calcium ([Ca²⁺]_i) transients. In contrast, ATP promoted [Ca²⁺]_i transients, but did not have any effects on NO production. SS rats fed a HS diet for 3 weeks demonstrated impaired NO production: the response to Ang II or H₂O₂ in podocytes of glomeruli isolated from SS rats fed a HS diet was significantly reduced compared to rats fed a LS diet. Therefore, glomerular podocytes from hypertensive rats showed a diminished NO release in response to Ang II or oxidative stress, suggesting that podocytic NO signaling is dysfunctional in this condition and likely contributes to the development of kidney injury.

Combined effect of hydrogen sulphide donor and losartan in experimental diabetic nephropathy in rats

Background

Diabetic nephropathy (DN) is one of the complex complications of Diabetes Mellitus (DM). The present study has been designed to examine protective role of hydrogen Sulphide (H₂S) donor against streptozotocin (STZ) -induced behavioral, oxidative abnormalities and its DN like symptoms in rats.

Methods

For the induction of DN single intraperitoneal administration of STZ (45 mg/kg) was given till third week. Behavioral parameters were measured on 1st, 7th, 21st and 42nd days and biochemical parameters were performed on 42nd day. All the drug treatments [NaHS (10 & 30 μmol/kg i.p), DL-propargylglycine (10 mg/kg i.p), standard drug- Losartan (5 mg/kg p.o)] were given for 3 weeks staring from 21st day after the STZ injection.

Results

Three weeks treatment with sodium hydrosulphide (NaHS) (10 and 30 μmol/kg i.p,) significantly attenuated the behavioral and biochemical abnormalities in STZ-treated animals. DL-propargylglycine (10 mg/kg i.p) pretreatment with sub-effective dose of NaHS (30 μmol/kg i.p) significantly reversed the protective effect of NaHS. However, combination of both NaHS (30 μmol/kg i.p) and standard drug losartan (5 mg/kg p.o) potentiated their effects as compared to their effect alone.

Conclusion

The results of the present study suggest that H₂S treatment showed significant improvement in behavioral and biochemical abnormalities induced by STZ administration. Thus H₂S represents a target of treatment to prevent the progression of complications by DN.

Flavonoid rich fraction of Punica granatum improves early diabetic nephropathy by ameliorating proteinuria and disturbed glucose homeostasis in experimental animals

CONTEXT

Different parts of Punica granatum Linn. (Punicaceae) are traditionally used as renal protective agents in the Indian system of medicine. However, there is paucity of information regarding its role in diabetic nephropathy.

OBJECTIVE

The present study investigates the nephroprotective potential of flavonoid-rich fraction of P. granatum leaves in streptozotocin (STZ)-induced early diabetic nephropathy in experimental animals.

MATERIALS AND METHODS

Experimental diabetic nephropathy was induced in Wistar rats by single intraperitonial injection of STZ (65 mg/kg) dissolved in ice cold citrophosphate buffer (pH 4.3). After induction rats were divided into five groups (6 normal; 24 diabetic) and administered with glibenclamide (5 mg/kg) and three dose levels of flavonoid-rich fraction of P. granatum leaves (PGFF), i.e. 50, 100, and 200 mg/kg body weight/day for 28 d. Fasting blood glucose, lipid profile, serum albumin, serum total protein, serum creatinine, blood urea nitrogen (BUN) glycosylated hemoglobin, and biomarkers of kidney oxidative stress were assessed at the end of the treatment period. Urine was analyzed for the measurement of total protein, albumin, and creatinine clearance. Kidney sections were subjected to histopathological study.

RESULTS

Daily oral administration of variable dose levels of PGFF for 28 d normalized various biochemical, metabolic, and histopathological changes in the diabetic rats. PGFF significantly (p < 0.01 and p < 0.05) improved the glycemic status and renal function in diabetic rats as compared with diabetic control rats.

DISCUSSION AND CONCLUSION

The results of our study thus prove the protective effect of PGFF in early diabetic nephropathy by ameliorating proteinuria and disturbed glucose homeostasis in experimental animals.

Combination therapy with an angiotensin-converting-enzyme inhibitor and an angiotensin II receptor antagonist ameliorates microinflammation and oxidative stress in patients with diabetic nephropathy

Aims/Introduction

Recent studies have pointed to the effectiveness of combination therapy with an angiotensin‐converting‐enzyme inhibitor (ACEI) and an angiotensin receptor blocker (ARB) for diabetic nephropathy. However, some controversy over this combination treatment remains and the mechanisms underlying its renoprotective effects have not been fully clarified. Therefore, we compared the renoprotective effects of imidapril (ACEI) and losartan (ARB) combination therapy with losartan monotherapy in patients with diabetic nephropathy. We also compared the anti‐inflammatory and anti‐oxidative stress effects of these two treatments.

Materials and Methods

A total of 32 Japanese patients with type 2 diabetes and nephropathy were enrolled. Patients were randomized to either 100 mg/day losartan (n = 16) or 50 mg/day losartan plus 5 mg/day imidapril (n = 16). We evaluated clinical parameters, serum concentrations of high‐sensitivity C‐reactive protein (hs‐CRP), soluble intercellular adhesion molecule‐1 (sICAM‐1), interleukin‐18 (IL‐18) and monocyte chemotactic protein‐1 (MCP‐1), and the urinary concentrations of IL‐18, MCP‐1 and 8‐hydroxy‐2′‐deoxyguanosine (8‐OHdG) at 24 and 48 weeks after starting treatment.

Results

Blood pressure was not significantly different between the two groups. The serum levels of hs‐CRP, sICAM‐1 and IL‐18, as well as urinary excretion of albumin, IL‐18 and 8‐OHdG decreased significantly in the combination therapy group at 48 weeks. The percent decreases in serum IL‐18 concentrations and urinary IL‐18 and 8‐OHdG were significantly greater in the combination therapy group than in the monotherapy group.

Conclusions

Combination therapy with an ACEI and an ARB could be beneficial for treating diabetic nephropathy through its anti‐inflammatory and anti‐oxidative stress effects.

Preventive effects of syngeneic bone marrow transplantation on diabetic nephropathy in mice

Treatment with autologous bone marrow transplantation (ABMT) can change the natural history of diabetes in patients with new-onset Type 1 diabetes (T1D). Effects of syngeneic bone marrow transplantation (syn-BMT) on diabetic nephropathy were studied in streptozotocin-induced diabetic mice. Diabetic mice received sibling's bone marrow on days 3, 10, 20, or 40 after T1D onset, respectively. Renal pathology, levels of oxidative stress, and the expressions of angiotensinogen (AGT), monocyte chemoattractant protein-1 (MCP-1) and transforming growth factor beta 1 (Tgf-beta1) mRNA were investigated. Treatment with syn-BMT when disease was early-onset reduced mesangial area expansion and kidney enlargement; besides, if it is given on day 10, syn-BMT attenuated glomerular hypertrophy. Oxidative stress factors such as catalase (CAT) and superoxide radical anion O(2-) (O(2-)) were markedly maintained by syn-BMT compared to mice without treatment. In diabetic mice without treatment, renal AGT and MCP-1 mRNA were increased, while they were effectively suppressed by syn-BMT. But it showed no changes or even increment in Tgf-beta1 mRNA after syn-BMT. Syn-BMT, if applied when disease was early-onset, ameliorated diabetic renal injury. These preventive effects could be partly via maintaining oxidative stress and expression of AGT and MCP-1 in kidney in streptozotocin-diabetic mice.

Antenatal glucocorticoid therapy increase cardiac alpha-enolase levels in fetus and neonate rats

AIMS

Antenatal glucocorticoid therapy has been shown to prevent acute diseases including infant respiratory distress syndrome and reduce mortality, although little is known about the effects on cardiac function-related proteins in the fetus or neonate. We investigated whether cardiac function-related proteins were altered in cardiac tissues of fetuses and neonates born to pregnant rats treated by glucocorticoid.

MAIN METHODS

Dexamethasone (DEX) was administered to pregnant rats for 2 days on day 17 and 18 or day 19 and 20 of gestation to simulate antenatal DEX therapy, and cardiac tissues of 19- and 21-day fetuses and 1-, 3-, and 5-day neonates were analyzed using a proteomic technique with liquid chromatography-mass spectrometry/mass spectrometry.

KEY FINDINGS

The identified five proteins; alpha-enolase, creatine kinase-M type, beta-tubulin, troponin T, and ATP synthase beta-chain, were significantly increased in fetal cardiac tissues with DEX administration. We observed that significant increase of alpha-enolase in the 19-day fetuses by DEX using Western blotting and immunohistochemistry. ATP and cAMP levels were also increased in the fetal heart tissue. In addition, pyruvate levels were significantly increased in the fetus groups by DEX.

SIGNIFICANCE

These results suggest that increased alpha-enolase may contribute to acceleration of glycolysis in the preterm heart.

Protective effects of antioxidant-fortified diet on renal function and metabolic profile in obese Zucker rat

Oxidative stress contributes to the pathophysiology of type 2 diabetes mellitus and its complications, including nephropathy. The current study was designed to test the hypothesis that a diet fortified with antioxidants would be beneficial to delay or prevent the progression of this disease. Male and female Zucker fa/fa rats were fed a control or an antioxidant (AO)-fortified diet starting at 4 weeks of age. Metabolic parameters, renal function, and renal histopathology were analyzed at 6, 13, and 20 weeks of age. Females on the AO diet had significantly lower blood glucose at 6 and 13 weeks, less severe renal pathology at 20 weeks, and higher glomerular filtration rates (GFR) at 20 weeks than age-matched females on the regular diet (P < 0.05). Metabolic parameters including blood glucose, insulin resistance, and serum cholesterol, and mean arterial pressure (MAP), worsened with age in both males and females, as expected. GFR decreased and renal pathology also became more severe with age. Finally, females on the AO diet had higher GFRs and lower MAP at 20 weeks than males on the same diet. This may denote a protective effect of the AO diet in females, but not in males. These findings may have implications for the role of antioxidants as therapy in humans with T2DM.

Ameliorative effect of combination of benfotiamine and fenofibrate in diabetes-induced vascular endothelial dysfunction and nephropathy in the rat

The study has been designed to investigate the effect of benfotiamine and fenofibrate in diabetes-induced experimental vascular endothelial dysfunction (VED) and nephropathy. The single administration of streptozotocin (STZ) (50 mg/kg, i.p.) produced diabetes, which was noted to develop VED and nephropathy in 8 weeks. The diabetes produced VED by attenuating acetylcholine-induced endothelium dependent relaxation, impairing the integrity of vascular endothelium, decreasing serum nitrite/nitrate concentration and increasing serum TBARS and aortic superoxide anion generation. Further, diabetes altered the lipid profile by increasing the serum cholesterol, triglycerides and decreasing the high density lipoprotein. The nephropathy was noted to be developed in the diabetic rat that was assessed in terms of increase in serum creatinine, blood urea, proteinuria, and glomerular damage. The benfotiamine (70 mg/kg, p.o.) and fenofibrate (32 mg/kg, p.o.) or lisinopril (1 mg/kg, p.o., a standard agent) treatments were started in diabetic rats after 1 week of STZ administration and continued for 7 weeks. The treatment with benfotiamine and fenofibrate either alone or in combination attenuated diabetes-induced VED and nephropathy. In addition, the combination of benfotiamine and fenofibrate was noted to be more effective in attenuating the diabetes-induced VED and nephropathy when compared to treatment with either drug alone or lisinopril. Treatment with fenofibrate normalizes the altered lipid profile in diabetic rats, whereas benfotiamine treatment has no effect on lipid alteration in diabetic rats. It may be concluded that diabetes-induced oxidative stress, lipids alteration, and consequent development of VED may be responsible for the induction of nephropathy in diabetic rats. Concurrent administration of benfotiamine and fenofibrate may provide synergistic benefits in preventing the development of diabetes-induced nephropathy by reducing the oxidative stress and lipid alteration, preventing the VED and subsequently improving the renal function.

Renal and metabolic effects of tempol in obese ZSF1 rats--distinct role for superoxide and hydrogen peroxide in diabetic renal injury

Oxidative stress, that is, overproduction of reactive oxygen species and reduced antioxidant system activity, is implicated in the pathogenesis of diabetic complications; and therefore, superoxide dismutase (SOD) mimetic tempol should be protective in diabetic kidney. However, the effects of tempol in metabolic syndrome-associated renal injury have not been thoroughly examined. In this study, we examined the effects of 9 weeks of treatment with tempol on metabolic status, renal oxidative stress, and kidney function and structure in obese, diabetic, hypertensive ZSF(1) rats and their nondiabetic, hypertensive, lean littermates. The obese rats had significantly reduced total SOD and catalase activity, increased peroxidase activity and lipid peroxidation, and higher level of protein oxidation in renal cortical tissue compared with their lean littermates. These changes were accompanied by renal injury (proteinuria; reduced excretory function; and markedly increased glomerular and interstitial inflammation, proliferation, and collagen IV synthesis). Tempol treatment slightly increased total SOD activity, significantly reduced lipid peroxidation and peroxidase activity, but had no effect on catalase and protein oxidation. Tempol had no effects on blood pressure, renal hemodynamics and excretory function, and proteinuria in obese rats, yet improved insulin sensitivity and reduced renal inflammatory, proliferative, and fibrotic changes. Because tempol possesses no catalase activity and, in diabetes, not only SOD but also catalase is inhibited, it is possible that the toxicity of hydrogen peroxide (H(2)O(2)) remains unaltered under tempol treatment. This study suggests that superoxide and H(2)O(2) may have distinct roles in the pathogenesis of diabetic renal injury, with superoxide mainly being involved in inflammatory, proliferative, and fibrotic changes, and H(2)O(2) in glomerular hemodynamics and proteinuria.

Maternal nicotine exposure increases oxidative stress in the offspring

Fetal and neonatal nicotine exposure causes beta-cell apoptosis and loss of beta-cell mass, but the underlying mechanisms are unknown. The goal of this study was to determine whether maternally derived nicotine can act via the pancreatic nicotinic acetylcholine receptor (nAChR) during fetal and neonatal development to induce oxidative stress in the pancreas. Female Wistar rats were given saline or nicotine (1 mg/kg/day) via subcutaneous injection for 2 weeks prior to mating until weaning (postnatal day 21). In male offspring, nAChR subunit mRNA expression was characterized in the developing pancreas and various oxidative stress markers were measured at weaning following saline and nicotine exposure. The nAChR subunits alpha2-alpha4, alpha6, alpha7, and beta2-beta4 were present in the pancreas during development. Fetal and neonatal exposure to nicotine significantly increased pancreatic GPx-1 and MnSOD protein expression, as well as islet ROS production. Furthermore, protein carbonyl formation was higher in nicotine-exposed offspring relative to controls, particularly within the mitochondrial fraction. There was also a nonsignificant trend toward higher serum 8-isoPG levels. These data suggest that beta-cell apoptosis in the fetal and neonatal pancreas may be the result of a direct effect of nicotine via its receptor and that this effect may be mediated through increased oxidative stress.

PPAR-alpha agonist fenofibrate induces renal CYP enzymes and reduces blood pressure and glomerular hypertrophy in Zucker diabetic fatty rats

We have previously shown that fenofibrate, a peroxisome proliferator-activated receptor-alpha activator, increases renal cytochrome P450 (CYP)-derived eicosanoids and improves endothelial function in pre-diabetic obese rats. The present study was designed to explore the efficacy of fenofibrate on blood pressure and renal injury in the advanced stage of type-2 diabetes. 26-week-old male Zucker diabetic fatty rats (ZDF) were fed fenofibrate (100 mg/kg/day) for 6 weeks. Chronic treatment with fenofibrate normalized systolic blood pressure and reduced glomerular size by 19% in diabetic rats. Western blot and fluorescent immunostaining revealed that the over-expression of collagen type IV and alpha-smooth muscle actin was significantly attenuated in the kidney of fenofibrate-treated ZDF (F-ZDF) rats. In addition, fenofibrate administration dramatically decreased the cyclin D1 protein level in the kidney of diabetic rats. In contrast, renal CYP2C23 and CYP4A proteins were significantly increased in F-ZDF rats. These fenofibrate effects were observed in the absence of significant changes in glucose, insulin or lipid levels. Taken together, our results demonstrate that fenofibrate may lower blood pressure and attenuate glomerular hypertrophy and collagen accumulation through the downregulation of cyclin D1 and upregulation of CYP monooxygenases in the late stage of type-2 diabetes.

Fasudil attenuates sympathetic nervous activity in the adrenal medulla of spontaneously hypertensive rats

We investigated the effects of fasudil, a Rho kinase inhibitor, on hypertension in spontaneously hypertensive rats and on the catecholamine synthetic pathway. Ten-week-old male SHR and Wistar-Kyoto rats were administered fasudil (10 mg/kg/day s.c.) for 4 days. Systolic blood pressure was measured using the tail-cuff method. Catecholamine levels were measured with high-performance liquid chromatography-ECD methods. Tyrosine hydroxylase protein levels were measured in Western blot analysis. The tyrosine hydroxylase mRNA level was measured using real-time PCR methods. Fasudil significantly decreased systolic blood pressure in spontaneously hypertensive rats, but not in Wistar-Kyoto rats. Fasudil also significantly decreased catecholamine, tyrosine hydroxylase protein, and tyrosine hydroxylase mRNA levels in the adrenal medulla of spontaneously hypertensive rats. These results suggest that the depressor effects of fasudil on hypertension in spontaneously hypertensive rats may be related to inhibition of the catecholamine synthetic pathway.