Differential effects of dietary flavonoids on adipogenesis.

PROPOSE: Obesity is a fast growing epidemic worldwide. During obesity, the increase in adipose tissue mass arise from two different mechanisms, namely, hyperplasia and hypertrophy. Hyperplasia which is the increase in adipocyte number is characteristic of severe obese patients. Recently, there has been much interest in targeting adipogenesis as therapeutic strategy against obesity. Flavonoids have been shown to regulate several pathways and affect a number of molecular targets during specific stages of adipocyte development. METHODS: Presently, we provide a review of key studies evaluating the effects of dietary flavonoids in different stages of adipocyte development with a particular emphasis on the investigations that explore the underlying mechanisms of action of these compounds in human or animal cell lines as well as animal models. RESULTS: Flavonoids have been shown to regulate several pathways and affect a number of molecular targets during specific stages of adipocyte development. Although most of the studies reveal anti-adipogenic effect of flavonoids, some flavonoids demonstrated proadipogenic effect in mesenchymal stem cells or preadipocytes. CONCLUSION: The anti-adipogenic effect of flavonoids is mainly via their effect on regulation of several pathways such as induction of apoptosis, suppression of key adipogenic transcription factors, activation of AMPK and Wnt pathways, inhibition of clonal expansion, and cell-cycle arrest.

Effect of pioglitazone on vasopressor responses to adrenergic agonists and angiotensin II in diabetic and non-diabetic spontaneously hypertensive rats.

Pioglitazone, peroxisome proliferator-activated receptor (PPAR-γ) agonist, is a therapeutic drug for diabetes. Present study investigated the interaction between PPAR-γ and alpha adrenoceptors in modulating vasopressor responses to Angiotensin II (Ang II) and adrenergic agonists, in diabetic & non-diabetic Spontaneously Hypertensive Rats (SHRs). Diabetes was induced with an i.p injection of streptozotocin (40 mg/kg) in two groups (STZ-CON, STZ-PIO), whereas two groups remained non diabetic (ND-CO, ND-PIO). One diabetic and non-diabetic group received Pioglitazone (10mg/kg) orally for 21 days. On day 28, the animals were anaesthetized with sodium pentobarbitone (60mg/kg) and prepared for measurement of systemic haemodynamics. Basal mean arterial pressure of STZ-CON was higher than ND-CON, whereas following pioglitazone treatment, MAP was lower compared to respective controls. MAP responses to i.v administration of NA, PE, ME and ANG II were significantly lower in diabetic SHRs: STZ-CON vs ND-CON (35%). Pioglitazone significantly decreased responses to NA, PE, ME and ANG II in ND-PIO versus ND-CON by 63%. Responses to NA and ANG II were significantly attenuated in STZ-PIO vs. ND-PIO (40%). PPAR-γ regulates systemic hemodynamic in diabetic model and cross-talk relationship exists between PPAR-γ and α1-adrenoceptors, ANG II in systemic vasculature of SHRs.

Effect of edaravone in diabetes mellitus-induced nephropathy in rats.

Edaravone, a synthetic-free radical scavenger, has been reported to reduce ischemia-reperfusion-induced renal injury by improving tubular cell function, and lowering serum creatinine and renal vascular resistance. The present study investigated the effect of edaravone in diabetes mellitus-induced nephropathy in rats. A single administration of streptozotocin (STZ, 55 mg/kg, i.p.) was employed to induce diabetes mellitus in rats. The STZ-administered diabetic rats were allowed for 10 weeks to develop nephropathy. Mean body weight, lipid alteration, renal functional and histopathology were analysed. Diabetic rats developed nephropathy as evidenced by a significant increase in serum creatinine and urea, and marked renal histopathological abnormalities like glomerulosclerosis and tubular cell degeneration. The kidney weight to body weight ratio was increased. Moreover, diabetic rats showed lipid alteration as evidenced by a signifi cant increase in serum triglycerides and decrease in serum high-density lipoproteins. Edaravone (10 mg/kg, i.p., last 4-weeks) treatment markedly prevented the development of nephropathy in diabetic rats by reducing serum creatinine and urea and preventing renal structural abnormalities. In addition, its treatment, without significantly altering the elevated glucose level in diabetic rats, prevented diabetes mellitus-induced lipid alteration by reducing serum triglycerides and increasing serum high-density lipoproteins. Interestingly, the renoprotective effect of edaravone was comparable to that of lisinopril (5 mg/kg, p.o, 4 weeks, standard drug). Edaravone prevented renal structural and functional abnormalities and lipid alteration associated with experimental diabetes mellitus. Edaravone has a potential to prevent nephropathy without showing an anti-diabetic action, implicating its direct renoprotection in diabetic rats.

Antioxidant and pro-oxidant effects of oil palm (Elaeis guineensis) leaves extract in experimental diabetic nephropathy: a duration-dependent outcome.

BACKGROUND: Catechins-rich oil palm (Elaeis guineensis) leaves extract (OPLE) is known to have antioxidant activity. Several polyphenolic compounds reported as antioxidants such as quercetin, catechins and gallic acid have been highlighted to have pro-oxidant activity at high doses. Therefore, the present study was conducted to investigate the antioxidant and pro-oxidant effects of chronically administering high dose of OPLE (1000 mg kg⁻¹) in an animal model of diabetic nephropathy (DN). METHODS: Animal body weight, indexes of glycaemia, renal function and morphology were assessed in diabetic animals with and without OPLE (1000 mg kg⁻¹) for 4 and 12 weeks respectively. Oxidative stress was quantified by measuring levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG), lipid peroxides (LPO) and reduced glutathione (GSH). Transforming growth factor-beta1 (TGF-ß1), a key mediator of extracellular matrix accumulation, was analysed in plasma. The mechanisms of OPLE action were evaluated by assessing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits (p22phox and p67phox) expression. RESULTS: Oral administration with high dose of catechins-rich OPLE (1000 mg kg⁻¹) to STZ-induced diabetic rats for 4 weeks attenuated renal dysfunction (hyperfiltration, proteinuria) and development of glomerulosclerosis and tubulointerstitial fibrosis, features that are associated with DN. Suppression of increases in oxidative stress markers (8-OHdG, LPO) and the fibrotic cytokine, TGF-ß1 was observed. OPLE also reduced renal expression of NADPH oxidase subunits p22phox and p67phox. In contrast and surprisingly, identical dose of OPLE when administered to diabetic animals for 12 weeks caused worsening of renal dysfunction, histopathology in addition to further elevation of oxidative stress marker (LPO) and TGF-ß1. These unfavourable effects of prolonged treatment with 1000 mg kg⁻¹ OPLE were accompanied by increase expression of one of the NADPH oxidase subunits, p22phox. CONCLUSION: Our study indicates that chronic administration of 1000 mg kg-1 OPLE exerts both antioxidant and pro-oxidant effects in DN depending on the duration of treatment. The present study also reveals that the antioxidant/pro-oxidant effects of OPLE are in part, due to modulation of NADPH activity.

The effect of high-fructose intake on the vasopressor response to angiotensin II and adrenergic agonists in Sprague-Dawley rats.

Effect of losartan was assessed on systemic haemodynamic responses to angiotensin II (Ang II) and adrenergic agonists in the model of high-fructose-fed rat. Twenty-four Sprague-Dawley (SD) rats were fed for 8 weeks either 20% fructose solution (FFR) or tap water (C) ad libitum. FFR or C group received losartan (10mg/kg/day p.o.) for 1 week at the end of feeding period (FFR-L and L) respectively, then the vasopressor responses to Ang II, noradrenaline (NA), phenylephrine (PE) and methoxamine (ME) were determined. The responses (%) to NA, PE, ME and Ang II in FFR were lower (P<0.05) than C (FFR vs. C; 22±2 vs. 32±2, 30±3 vs. 40±3, 9±1 vs. 13±1, 10±1 vs. 17±1) respectively. L group had blunted (P<0.05) responses to NA, PE, ME and Ang II compared to C (L vs. C; 26±2 vs. 32±2, 30±3 vs. 40±3, 7±0.7 vs. 13±1, 5±0.4 vs. 17±1) respectively. FFR-L group had aggravated (P<0.05) response to NA and ME, but blunted response to Ang II compared to FFR (FFR-L vs. FFR; 39±3 vs. 22±2, 11±1 vs. 9±1, 3±0.4 vs. 10±1) respectively. Fructose intake for 8 weeks results in smaller vasopressor response to adrenergic agonists and Ang II. Data also demonstrated an important role played by Ang II in the control of systemic haemodynamics in FFR and point to its interaction with adrenergic neurotransmission.

Chronic Administration of Oil Palm (Elaeis guineensis) Leaves Extract Attenuates Hyperglycaemic-Induced Oxidative Stress and Improves Renal Histopathology and Function in Experimental Diabetes.

Oil palm (Elaeis guineensis) leaves extract (OPLE) has antioxidant properties and because oxidative stress contributes to the pathogenesis of diabetic nephropathy (DN), we tested the hypothesis that OPLE prevents diabetes renal oxidative stress, attenuating injury. Sprague-Dawley rats received OPLE (200 and 500 mg kg(-1)) for 4 and 12 weeks after diabetes induction (streptozotocin 60 mg kg(-1)). Blood glucose level, body and kidney weights, urine flow rate (UFR), glomerular filtration rate (GFR), and proteinuria were assessed. Oxidative stress variables such as 8-hydroxy-2'-deoxyguanosine (8-OHdG), glutathione (GSH), and lipid peroxides (LPO) were quantified. Renal morphology was analysed, and plasma transforming growth factor-beta1 (TGF-ß1) was measured. Diabetic rats demonstrated increase in blood glucose and decreased body and increased kidney weights. Renal dysfunction (proteinuria, elevations in UFR and GFR) was observed in association with increases in LPO, 8-OHdG, and TGF-ß1 and a decrease in GSH. Histological evaluation of diabetic kidney demonstrated glomerulosclerosis and tubulointerstitial fibrosis. OPLE attenuated renal dysfunction, improved oxidative stress markers, and reduced renal pathology in diabetic animals. These results suggest OPLE improves renal dysfunction and pathology in diabetes by reducing oxidative stress; furthermore, the protective effect of OPLE against renal damage in diabetes depends on the dose of OPLE as well as progression of DN.

Exogenous hydrogen sulfide (H2S) reduces blood pressure and prevents the progression of diabetic nephropathy in spontaneously hypertensive rats.

The coexistence of hypertension and diabetes results in the rapid development of nephropathy. Hydrogen sulfide (H2S) is claimed to control the vascular and renal functions. This study tested the hypothesis that exogenous H2S lowers the blood pressure and decreases the progression of nephropathy in spontaneously hypertensive rats (SHR) that were diabetic. Eighteen SHR were divided into three groups: SHR, SHR diabetic, and SHR diabetic treated with a group of Wistar-Kyoto rats serving as normotensive nondiabetic control. Diabetes was induced with streptozotocin (STZ) in two groups and one diabetic group received sodium hydrosulfide (NaHS), a H2S donor for 5 weeks. Blood pressure was measured in conscious and anesthetized states and renal cortical blood perfusion in acute studies. Plasma and urinary H2S levels, creatinine concentrations, and electrolytes were measured on three different occasions throughout the 35-day period. Diabetic SHR had higher blood pressure, lower plasma and urinary H2S levels, and renal dysfunction as evidenced by increased plasma creatinine, creatinine clearance, and decreased urinary sodium-to-potassium ratio and renal cortical blood perfusion. NaHS reduced blood pressure, increased H2S levels in plasma and urinary excretion, and reversed the STZ-induced renal dysfunction. The findings of this study suggest that the administration of exogenous H2S lowers the blood pressure and confers protection against the progression of STZ-induced nephropathy in SHR.

Clinical characteristics, cytokine profiles and plasma IgE in adults with asthma.

Asthma is a disease with complicated network of inflammatory responses of cytokines and ImmunoglobulinE (IgE). The aim of this study was to explore the clinical characteristics, cytokine profile and plasma IgE in the Malaysian population. This is a cross-sectional study involving physician-diagnosed asthma patients (n = 287) recruited from the Chest Clinic, University of Malaya Medical Centre (UMMC). Blood (8 mL) was taken after consent was obtained. The peripheral blood leucocytes (PBL) were cultured in presence of a mitogen for 72 h to quantify cytokines [Interleukin-5(IL-5), Interleukin-9 (IL-9), Interleukin-12 Beta (IL-12ꞵ) and granulocyte-macrophage colony-stimulating factor (GM-CSF)] and plasma was used to quantify IgE levels with commercial ELISA kits. Results were compared against the same biomarkers in healthy subjects (n = 203). In addition, the amount of the biomarkers in the asthma patients were compared with their disease severity and clinical characteristics. Statistical tests in the SPSS software (Mann-Whitney U test and the Kruskal Wallis) were used to compare cytokine production and plasma IgE levels. The mean plasma IgE level was markedly higher (p < 0.0001) in asthmatics compared to controls. There were higher levels of IL-5, IL-9, IL-12ꞵ and GM-CSF (p < 0.0001) produced by cultured PBL from asthma patients compared to controls. However, our results did not expose a significant association between these cytokine levels and severity and clinical symptoms of asthma. However, there was a marked association between asthma severity and blood lymphocyte count [ꭓ2(2) = 6.745, p < 0.05]. These findings support the roles played by cytokines and IgE in the airway inflammation in asthma. The findings of this study provide new information about inflammatory cytokines in Malaysian asthma patients.

Renal Nano-drug delivery for acute kidney Injury: Current status and future perspectives.

Acute kidney injury (AKI) causes considerable morbidity and mortality, particularly in the case of post-cardiac infarction or kidney transplantation; however, the site-specific accumulation of small molecule reno-protective agents for AKI has often proved ineffective due to dynamic fluid and solute excretion and non-selectivity, which impedes therapeutic efficacy. This article reviews the current status and future trajectories of renal nanomedicine research for AKI management from pharmacological and clinical perspectives, with a particular focus on appraising nanosized drug carrier (NDC) use for the delivery of reno-protective agents of different pharmacological classes and the effectiveness of NDCs in improving renal tissue targeting selectivity and efficacy of said agents. This review reveals the critical shift in the role of the small molecule reno-protective agents in AKI pharmacotherapy - from prophylaxis to treatment - when using NDCs for delivery to the kidney. We also highlight the need to identify the accumulation sites of NDCs carrying reno-protective agents in renal tissues during in vivo assessments and detail the less-explored pharmacological classes of reno-protective agents whose efficacies may be improved via NDC-based delivery. We conclude the paper by outlining the challenges and future perspectives of NDC-based reno-protective agent delivery for better clinical management of AKI.

Exposure to High-Fat Style Diet Induced Renal and Liver Structural Changes, Lipid Accumulation and Inflammation in Intact and Ovariectomized Female Rats.

PURPOSE: We hypothesized that low estrogen levels aggravate obesity-related complications. Diet-induced obesity can cause distinct pathologies, including impaired glucose tolerance, inflammation, and organ injury that leads to fatty liver and chronic kidney diseases. To test this hypothesis, ovariectomized (OVX) rats were fed a high-fat style diet (HFSD), and we examined structural changes and inflammatory response in the kidney and liver. METHODS: Sprague-Dawley female rats were ovariectomized or sham-operated and divided into four groups: sham-operated rats fed a normal diet (ND); ovariectomized rats fed a normal diet (OVX-ND); sham-operated rats fed a HFSD; ovariectomized rats fed a high-fat style diet (OVX-HFSD). Mean blood pressure and fasting blood glucose were measured on weeks 0 and 10. The rats were sacrificed 10 weeks after initiation of ND or HFSD, the kidney and liver were harvested for histological, immunohistochemical and immunofluorescence studies. RESULTS: HFSD-fed rats presented a significantly greater adiposity index compared to their ND counterparts. Liver index, fasting blood glucose and mean blood pressure was increased in OVX-HFSD rats compared to HFSD rats at study terminal. Histological and morphometric studies showed focal interstitial mononuclear cell infiltration in the kidney of HFSD rats with mesangial expansion being greater in the OVX-HFSD rats. Both HFSD fed groups showed increased expressions of renal inflammatory markers, namely TNF-alpha, IL-6 and MCP-1, and infiltrating M1 macrophages with some influence of ovarian hormonal status. HFSD-feeding also caused hepatocellular steatosis which was aggravated in ovariectomized rats fed the same diet. Furthermore, hepatocellular ballooning was observed only in the OVX-HFSD rats. Similarly, HFSD-fed rats showed increased expressions of the inflammatory markers and M1 macrophage infiltration in the liver; however, only IL-6 expression was magnified in the OVX-HFSD. CONCLUSION: Our data suggest that some of the structural changes and inflammatory response in the kidney and liver of rats fed a HFSD are exacerbated by ovariectomy.

Comparison of high-fat style diet-induced dysregulation of baroreflex control of renal sympathetic nerve activity in intact and ovariectomized female rats: Renal sympathetic nerve activity in high-fat style diet fed intact and ovariectomized female rats.

IMPACT STATEMENT: Over activation of renal sensory nerve in obesity blunts the normal regulation of renal sympathetic nerve activity. To date, there is no investigation that has been carried out on baroreflex regulation of renal sympathetic nerve activity in obese ovarian hormones deprived rat model, and the effect of renal denervation on the baroreflex regulation of renal sympathetic nerve activity. Thus, we investigated the role of renal innervation on baroreflex regulation of renal sympathetic nerve activity in obese intact and ovariectomized female rats. Our data demonstrated that in obese states, the impaired baroreflex control is indistinguishable between ovarian hormones deprived and non-deprived states. This study will be of substantial interest to researchers working on the impact of diet-induced hypertension in pre- and postmenopausal women. This study provides insight into health risks amongst obese women regardless of their ovarian hormonal status and may be integrated in preventive health strategies.

Functional subtypes of renal alpha1-adrenoceptor in spontaneously hypertensive rats with streptozotocin-induced experimental diabetic nephropathy.

AIM: This study investigated the impact of hypertension combined with diabetic nephropathy on rat renal alpha(1)-adrenoceptor subtype composition. METHODS: In streptozotocin-induced diabetic spontaneously hypertensive rats (SHR), diabetic nephropathy developed as reflected by increased kidney index, plasma creatinine, albumin excretion, creatinine clearance and fractional excretion of Na(+) (all p < 0.05). Renal vasoconstrictions caused by electrical stimulation of renal nerves and intrarenally administered noradrenaline (alpha-adrenoceptor agonist), phenylephrine (alpha(1)-adrenoceptor agonist) and methoxamine (alpha(1A)-adrenoceptor agonist) were determined in the presence and absence of intrarenally administered amlodipine (Ca(2+) channel blocker), 5-methylurapidil (alpha(1A)-adrenoceptor antagonist), chloroethylclonidine (alpha(1B)-adrenoceptor antagonist) and BMY 7378 (alpha(1D)-adrenoceptor antagonist). RESULTS: In diabetic nephropathy SHR, there was a significant (all p < 0.05) attenuation of all adrenergically induced vasoconstrictor responses in the antagonists, except chloroethylclonidine, which caused a significant (all p < 0.05) enhancement of the responses. CONCLUSION: The data demonstrated that there was a functional coexistence of alpha(1A)- and alpha(1D)-adrenoceptors in the renal vasculature of SHR irrespective of the presence of diabetic nephropathy. However, there was a minor contribution of pre-synaptic alpha-adrenoceptors to the adrenergically mediated vasoconstrictor responses in the diabetic nephropathy SHR.

Withaferin A inhibits adipogenesis in 3T3-F442A cell line, improves insulin sensitivity and promotes weight loss in high fat diet-induced obese mice.

The increased prevalence of obesity and associated insulin resistance calls for effective therapeutic treatment of metabolic diseases. The current PPARγ-targeting antidiabetic drugs have undesirable side effects. The present study investigated the anti-diabetic and anti-obesity effects of withaferin A (WFA) in diet-induced obese (DIO) C57BL/6J mice and also the anti-adipogenic effect of WFA in differentiating 3T3- F442A cells. DIO mice were treated with WFA (6 mg/kg) or rosiglitazone (10 mg/kg) for 8 weeks. At the end of the treatment period, metabolic profile, liver function and inflammatory parameters were obtained. Expression of selective genes controlling insulin signaling, inflammation, adipogenesis, energy expenditure and PPARγ phosphorylation-regulated genes in epididymal fats were analyzed. Furthermore, the anti-adipogenic effect of WFA was evaluated in 3T3- F442A cell line. WFA treatment prevented weight gain without affecting food or caloric intake in DIO mice. WFA-treated group also exhibited lower epididymal and mesenteric fat pad mass, an improvement in lipid profile and hepatic steatosis and a reduction in serum inflammatory cytokines. Insulin resistance was reduced as shown by an improvement in glucose and insulin tolerance and serum adiponectin. WFA treatment upregulated selective insulin signaling (insr, irs1, slc2a4 and pi3k) and PPARγ phosphorylation-regulated (car3, selenbp1, aplp2, txnip, and adipoq) genes, downregulated inflammatory (tnf-α and il-6) genes and altered energy expenditure controlling (tph2 and adrb3) genes. In 3T3- F442A cell line, withaferin A inhibited adipogenesis as indicated by a decrease in lipid accumulation in differentiating adipocytes and protein expression of PPARγ and C/EBPα. The effect of rosiglitazone on physiological and lipid profiles, insulin resistance, some genes expression and differentiating adipocytes were markedly different. Our data suggest that WFA is a promising therapeutic agent for both diabetes and obesity.

Functional subtypes of renal alpha1-adrenoceptor in diabetic and non-diabetic 2K1C Goldblatt renovascular hypertension.

AIM: This study investigates the subtypes of the alpha1-adrenoceptor mediating the adrenergically-induced renal vasoconstrictor responses in streptozotocin-induced diabetic and non-diabetic 2-kidney one clip (2K1C) Goldblatt hypertensive rats. METHODS: The renal blood flow responses to renal nerve stimulation, noradrenaline, phenylephrine, and methoxamine were measured in the absence and presence of nitrendipine, 5-methylurapidil, chloroethylclonidine and BMY 7378. RESULTS: The renal vasoconstrictor responses were markedly attenuated by nitrendipine and 5- methylurapidil in the diabetic rats (all P< 0.05). In the non-diabetic rats, these responses were markedly attenuated by nitrendipine, 5-methylurapidil, and BMY 7378 (all P< 0.05). In both experimental groups, chloroethylclonidine markedly accentuated the renal vasoconstrictions caused by all the adrenergic stimuli (all P< 0.05). CONCLUSION: These observations indicate that alpha 1A-adrenoceptor subtypes play a major role in mediating adrenergically-induced renal vasoconstriction in the diabetic 2K1C Goldblatt hypertensive rats. In the non-diabetic 2K1C Goldblatt hypertensive rats, contributions of alpha 1A and alpha 1D-adrenoceptor subtypes were proposed. Apart from post-synaptic alpha 1-adrenoceptors, both in the diabetic and non-diabetic 2K1C Goldblatt hypertensive rats, the potential involvement of presynaptic alpha 1- adrenoceptors is also suggested.

Effect of TGF-beta1 antisense oligodeoxynucleotide on renal function in chronic renal failure rats.

AIM: The aim of the present study was to investigate the effectiveness of transforming growth factor (TGF)-beta1 antisense oligodeoxynucleotides (ODN) in ameliorating deteriorated kidney function in rats with puromycin-induced chronic renal failure (CRF). METHODS: Saline, puromycin, puromycin+TGF-beta1 antisense ODN or puromycin+scrambled ODN were administered to unilaterally nephrectomized rats. Renal hemodynamic and excretory measurements were taken in the anaesthetized rats that had undergone surgical procedure. RESULTS: It was observed that in the CRF rats, there was a marked reduction in the renal blood flow (RBF), glomerular filtration rate (GFR), severe proteinuria, and almost 6-fold increased fractional excretion of sodium (FE Na+) as compared to that in the control rats (all P<0.05). It was further observed that in the CRF rats, the treatment with TGF-beta1 antisense, but not scrambled ODN, markedly attenuated the reduction of RBF, GFR, and proteinuria and markedly prevented the increase of the FE Na+ (all P<0.05). In addition, the renal hypertrophy in the CRF group (P<0.05 vs non-renal failure control) was markedly attenuated after treatment with TGF-1 antisense ODN (P<0.05). Focal segmental glomerulosclerosis was evident only in the untreated and scrambled ODN-treated CRF groups. An interesting observation of this study was that in the CRF rats, although there was marked attenuating and preventive effects of the TGF-beta1 antisense ODN on the deteriorated renal functions, the antisense treatment did not cause any marked change in the renal expression of TGF-beta1 at the protein level. CONCLUSION: Collectively, the data obtained suggests that TGF-beta1 antisense ODN possesses beneficial effects in puromycininduced chronic renal failure and that the deterioration in morphology and impaired renal function in this pathological state is in part dependent upon the action of TGF-beta1 within the kidney.

Cisplatin-induced nephrotoxicity causes altered renal hemodynamics in Wistar Kyoto and spontaneously hypertensive rats: role of augmented renal alpha-adrenergic responsiveness.

The pathogenesis of cisplatin-induced renal failure is related to reduced renal blood flow due to severe tubular damage and enhanced renovascular resistance. It is also known that alpha(1)-adrenoceptors, the major subtype of alpha-adrenoceptors in renal vasculature play the pivotal role in regulating renal hemodynamics. With this background, we have hypothesized that the altered renal hemodynamics and enhanced renovascular resistance in cisplatin-induced renal failure might be caused by the altered alpha-adrenergic responsiveness with a possible involvement of alpha(1)-adrenoceptors in the renal vasculature. In a unique experimental approach with anesthetized rats, this study has therefore examined if there is any shift in the renovascular responsiveness to renal nerve stimulation and a series of alpha-adrenergic agonists in Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats with cisplatin-induced renal failure in comparison with their body weight-matched normal controls. Thirty-two male rats of both WKY (n=16) and SHR (n=16) origin with body weight 236+/-7.9 g received cisplatin (5mg/kg i.p.). The renal failure was confirmed in terms of significantly reduced renal blood flow, reduced creatinine clearance, increased fractional excretion of sodium, increased kidney index (all P<0.05) and tubular damage. After 7 days of cisplatin, the overnight fasted rats were anesthetized (sodium pentobarbitone, 60 mg/kg i.p.) and renal vasoconstrictor experiments were done. The changes in the vasoconstrictor responses were determined in terms of reductions in renal blood flow caused by electrical renal nerve stimulation or intrarenal administration of noradrenaline, phenylephrine and methoxamine. It was observed that in the cisplatin-treated renal failure WKY and SHR rats there were significant (all P<0.05) reductions in the renal blood flow along with significantly (P<0.05) higher renal adrenergic responsiveness as compared with their non-renal failure controls. The data showed that in the renal failure WKY and SHR rats, the altered renal hemodynamics might be caused by an augmented renal adrenergic responsiveness. The results obtained further led us to suggest that the augmented renal adrenergic responsiveness in the cisplatin-induced renal failure rats were possibly mediated by the alpha(1)-adrenoceptors.

Renal targeting potential of a polymeric drug carrier, poly-l-glutamic acid, in normal and diabetic rats.

BACKGROUND AND PURPOSE: Poly-l-glutamic acid (PG) has been used widely as a carrier to deliver anticancer chemotherapeutics. This study evaluates PG as a selective renal drug carrier. EXPERIMENTAL APPROACH: 3H-deoxycytidine-labeled PGs (17 or 41 kDa) and 3H-deoxycytidine were administered intravenously to normal rats and streptozotocin-induced diabetic rats. The biodistribution of these compounds was determined over 24 h. Accumulation of PG in normal kidneys was also tracked using 5-(aminoacetamido) fluorescein (fluoresceinyl glycine amide)-labeled PG (PG-AF). To evaluate the potential of PGs in ferrying renal protective anti-oxidative stress compounds, the model drug 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF) was conjugated to 41 kDa PG to form PG-AEBSF. PG-AEBSF was then characterized and evaluated for intracellular anti-oxidative stress efficacy (relative to free AEBSF). RESULTS: In the normal rat kidneys, 17 kDa radiolabeled PG (PG-Tr) presents a 7-fold higher, while 41 kDa PG-Tr shows a 15-fold higher renal accumulation than the free radiolabel after 24 h post injection. The accumulation of PG-AF was primarily found in the renal tubular tissues at 2 and 6 h after an intravenous administration. In the diabetic (oxidative stress-induced) kidneys, 41 kDa PG-Tr showed the greatest renal accumulation of 8-fold higher than the free compound 24 h post dose. Meanwhile, the synthesized PG-AEBSF was found to inhibit intracellular nicotinamide adenine dinucleotide phosphate oxidase (a reactive oxygen species generator) at an efficiency that is comparable to that of free AEBSF. This indicates the preservation of the anti-oxidative stress properties of AEBSF in the conjugated state. CONCLUSION/IMPLICATIONS: The favorable accumulation property of 41 kDa PG in normal and oxidative stress-induced kidneys, along with its capabilities in conserving the pharmacological properties of the conjugated renal protective drugs, supports its role as a potential renal targeting drug carrier.

Withaferin A protects against palmitic acid-induced endothelial insulin resistance and dysfunction through suppression of oxidative stress and inflammation.

Activation of inflammatory pathways via reactive oxygen species (ROS) by free fatty acids (FFA) in obesity gives rise to insulin resistance and endothelial dysfunction. Withaferin A (WA), possesses both antioxidant and anti-inflammatory properties and therefore would be a good strategy to suppress palmitic acid (PA)-induced oxidative stress and inflammation and hence, insulin resistance and dysfunction in the endothelium. Effect of WA on PA-induced insulin resistance in human umbilical vein endothelial cells (HUVECs) was determined by evaluating insulin signaling mechanisms whilst effect of this drug on PA-induced endothelial dysfunction was determined in acetylcholine-mediated relaxation in isolated rat aortic preparations. WA significantly inhibited ROS production and inflammation induced by PA. Furthermore, WA significantly decreased TNF-α and IL-6 production in endothelial cells by specifically suppressing IKKß/NF-κß phosphorylation. WA inhibited inflammation-stimulated IRS-1 serine phosphorylation and improved the impaired insulin PI3-K signaling, and restored the decreased nitric oxide (NO) production triggered by PA. WA also decreased endothelin-1 and plasminogen activator inhibitor type-1 levels, and restored the impaired endothelium-mediated vasodilation in isolated aortic preparations. These findings suggest that WA inhibited both ROS production and inflammation to restore impaired insulin resistance in cultured endothelial cells and improve endothelial dysfunction in rat aortic rings.

Renin-Angiotensin System Gene Variants and Type 2 Diabetes Mellitus: Influence of Angiotensinogen.

Genome-wide association studies (GWAS) have been successfully used to call for variants associated with diseases including type 2 diabetes mellitus (T2DM). However, some variants are not included in the GWAS to avoid penalty in multiple hypothetic testing. Thus, candidate gene approach is still useful even at GWAS era. This study attempted to assess whether genetic variations in the renin-angiotensin system (RAS) and their gene interactions are associated with T2DM risk. We genotyped 290 T2DM patients and 267 controls using three genes of the RAS, namely, angiotensin converting enzyme (ACE), angiotensinogen (AGT), and angiotensin II type 1 receptor (AGTR1). There were significant differences in allele frequencies between cases and controls for AGT variants (P = 0.05) but not for ACE and AGTR1. Haplotype TCG of the AGT was associated with increased risk of T2DM (OR 1.92, 95% CI 1.15-3.20, permuted P = 0.012); however, no evidence of significant gene-gene interactions was seen. Nonetheless, our analysis revealed that the associations of the AGT variants with T2DM were independently associated. Thus, this study suggests that genetic variants of the RAS can modestly influence the T2DM risk.

Interaction between irbesartan, peroxisome proliferator-activated receptor (PPAR-γ), and adiponectin in the regulation of blood pressure and renal function in spontaneously hypertensive rats.

Adiponectin exerts vasodilatory effects. Irbesartan, an angiotensin receptor blocker, possesses partial peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist activity and increases circulating adiponectin. This study explored the effect of irbesartan alone and in combination with adiponectin on blood pressure, renal hemodynamic excretory function, and vasoactive responses to angiotensin II and adrenergic agonists in spontaneously hypertensive rat (SHR). Irbesartan was given orally (30 mg/kg/day) for 28 days and adiponectin intraperitoneally (2.5 µg/kg/day) for last 7 days. Groups of SHR received either irbesartan or adiponectin or in combination. A group of Wistar Kyoto rats (WKY) served as controls. Metabolic data and plasma samples were taken on days 0, 21, and 28. In acute studies, the renal vasoconstrictor actions of angiotensin II (ANGII), noradrenaline (NA), phenylephrine (PE), and methoxamine (ME) were determined. SHR control rats had a higher mean blood pressure than the WKY (132 ± 7 vs. 98 ± 2 mmHg), lower plasma and urinary adiponectin, creatinine clearance, urine flow rate and sodium excretion, and oxidative stress markers compared to WKY (all P < 0.05) which were progressively normalized by the individual drug treatments and to a greater extent by combined treatment. Responses to intrarenal administration of NA, PE, ME, and ANGII were larger in SHR (P < 0.05) than WKY by 20-25 %. Irbesartan enhanced (P < 0.05) responses to NA and PE, while adiponectin blunted responses to all vasoconstrictors (all P < 0.05). Combined treatment in SHR further decreased the renal vascular responses to ANGII. These findings suggest that an interactive relationship may exist between PPAR-γ, alpha adrenoceptors, and ANGII in the renal vasculature of the SHR.