Effects of mycophenolate mofetil on cisplatin-induced renal dysfunction in rats

Evaluation of nefrotoxicity by tacrolimus and micophenolate mofetil associated with kidney ischemia and reperfusion: experimental study in rats

OBJECTIVE

to evaluate the renal toxicity caused by tacrolimus and mycophenolate mofetil (MMF) in a single kidney ischemia and reperfusion model.

METHOD

experimental study using Wistar rats, submitted to right nephrectomy and left renal ischemia for 20 minutes, separated into groups in the postoperative period (PO): 1) Control (nonoperated); 2) Sham (operated, without PO drug); 3) TAC0.1, TAC1 and TAC10, tacrolimus administered PO at doses of 0.1mg/kg, 1mg/kg and 10mg/kg via gavage, respectively; 4) MMF, administered mycophenolate mofetil 20mg/kg; 5) MMF/TAC1 and MMF/TAC0.5, with an association of mycophenolate mofetil 20mg/kg and tacrolimus 1mg/kg and 0.5mg/kg, respectively. They were killed on the 14th PO and the kidney was removed for tissue oxidative stress analysis, by the dosage of reduced glutathione (GSH), lipoperoxidation (LPO) and protein carbonylation (PCO), and histological analysis by glomerular stereology (Glomerular volume density, Numerical density glomerular and mean glomerular volume). Renal function was evaluated by the measurement of serum creatinine and urea.

RESULTS

both drugs caused alterations in renal function, and the toxicity of tacrolimus was dose-dependent. Subacute toxicity did not show significant glomerular histological changes, and there was renal and compensatory glomerular hypertrophy in all groups except TAC10.

CONCLUSION

Both drugs cause changes in renal function. Glomerular morphometry and stereology showed negative interference of immunosuppressants during compensatory glomerular hypertrophy.

Avaliação da nefrotoxicidade pelo tacrolimus e micofenolato mofetil associados à isquemia e reperfusão renal: estudo experimental em ratos

RESUMO Objetivo: avaliar a toxicidade renal causada pelo tacrolimus e micofenolato mofetil (MMF) em um modelo de isquemia e reperfusão de rim único. Método: estudo experimental utilizando ratos Wistar, submetidos á nefrectomia direita e isquemia renal esquerda por 20 minutos, separados em grupos no pós- operatório (PO): 1) Controle (não operados); 2) Sham (operados, sem droga PO); 3) TAC0.1, TAC1 e TAC10, administrado tacrolimus no PO nas doses 0,1mg/kg, 1mg/kg e 10mg/kg via gavagem, respectivamentae; 4) MMF, administrado micofenolato mofetil 20mg/kg; 5) MMF/TAC1 e MMF/TAC0.5, com associação de micofenolato mofetil 20mg/kg e tacrolimus 1mg/kg e 0,5mg/kg, respectivamente. Foram mortos no 14º PO e retirado rim para análise do estresse oxidativo tecidual, pela dosagem de glutationa reduzida (GSH), lipoperoxidação (LPO) e carbonilação de proteínas (PCO), e análise histológica por estereologia glomerular (Densidade de volume glomerular, Densidade numérica glomerular e Volume glomerular médio). Foi avaliada função renal pela dosagem de creatinina e uréia séricas. Resultados: ambas drogas provocaram alteração na função renal, sendo a toxicidade do tacrolimus dosedependente. A toxicidade subaguda não mostrou alterações histológicas glomerulares significativas, sendo que houve hipertrofia renal e glomerular compensatória em todos os grupos exceto em TAC10. Conclusão: Ambas drogas provocam alteração na função renal. A morfometria e a estereologia glomerular mostraram interferência negativa dos imunossupressores durante a hipertrofia glomerular compensatória..

Renoprotective Effects of a New Free Radical Scavenger, XH-003, against Cisplatin-Induced Nephrotoxicity

Acute renal injury has an incidence of 25%–30% in patients with tumors who are treated with cisplatin and in patients for whom no specific drugs are available for treatment. Amifostine is the only FDA-approved chemoprotective drug; however, its clinical application is limited because of side effects. The small-molecule antioxidant XH-003, an acute radiation syndrome- (ARS-) protective drug independently developed in our laboratory, with 100% intellectual property rights, overcomes the side effects of amifostine but retains its high efficacy. In this study, XH-003 showed a chemoprotective effect similar to that of amifostine. A mechanistic study showed that XH-003 could significantly reduce cisplatin-induced increases in serum creatinine and urea nitrogen, increase the activity of antioxidant enzymes (SOD, CAT, and GSH-Px), reduce oxidative stress and tissue inflammation, and alleviate renal tissue damage by blocking the activity of the mitochondrial apoptosis pathway. Most importantly, XH-003 could reduce the accumulation of cisplatin in renal tissue by regulating the expression of proteins involved in cisplatin uptake and excretion, such as organic cation transporter 2 and MRP2. Moreover, in an in vivo xenotransplantation model, XH-003 did not interfere with the antitumor effect of cisplatin. These data provide strong evidence that the ARS-protective agent has a great potential for protecting against chemotherapy-induced toxicity. Thus, XH-003 can be considered in antitumor therapy.

Protective effects of dioscin against cisplatin-induced nephrotoxicity via the microRNA-34a/sirtuin 1 signalling pathway

BACKGROUND AND PURPOSE

Dioscin exhibits a range of pharmacological actions but little is known of its effects on cisplatin (CDDP)-induced nephrotoxicity. Here, we have assessed the effects and the possible mechanisms of dioscin against CDDP-induced nephrotoxicity.

EXPERIMENTAL APPROACH

We used an in vivo model of CDDP-induced nephrotoxicity in rats and mice and, in vitro, cultures of NRK-52E and HK-2 cells. The dual luciferase reporter assay was used to demonstrate modulation, by dioscin, of the targeting of sirtuin 1 (Sirt1) by microRNA (miR)-34a. Molecular docking assays were used to analyse the effects of dioscin with Sirt1, Keap1 and NF-κB.

KEY RESULTS

Dioscin attenuated cell damage in vitro and decreased renal injury in rats and mice, treated with CDDP. In terms of mechanisms, dioscin reversed CDDP-induced up-regulation of miR-34a and thus up-regulated Sirt1 levels. In addition, dioscin altered levels of haem oxygenase 1, glutathione-cysteine ligase subunits (GCLC, GCLM) and Keap1, along with increased nuclear translocation of Nrf2, thus decreasing oxidative stress. Also, dioscin affected levels of AP-1, COX-2, HMGB1, IκB-α, IL-1β, IL-6 and TNF-α and decreased the ratio of acetylated NF-κB and normal NF-κB, to suppress inflammation. From molecular docking assays, dioscin directly bound to Sirt1, Keap1 and NF-κBp65 by hydrogen bonding and/or hydrophobic interactions.

CONCLUSIONS AND IMPLICATIONS

Our results have linked CDDP-induced nephrotoxicity and the miR-34a/Sirt1 signalling pathway, which was modulated by dioscin. This natural product could be developed as a new candidate to alleviate CDDP-induced renal injury.

TNF-α, IL-6 and IL-10 expressions, responsible for disparity in action of curcumin against cisplatin-induced nephrotoxicity in rats

Cisplatin is a regularly employed effective chemotherapeutic agent for the treatment of many types of cancer. The main drawback of cisplatin treatment is kidney toxicity which affects 25-35% of treated patients. Many mechanisms are believed to be involved in this kidney damage, but inflammation plays a significant role in this event. Curcumin is a polyphenol and has antioxidant and anti-inflammatory effects. The purpose of this study was to determine the protective effects of curcumin on cisplatin-induced nephrotoxicity. Female rats were randomly divided into 5 groups: control, curcumin, cisplatin, curcumin plus cisplatin (pre-treatment group) and cisplatin plus curcumin (post-treatment group). Rats were given cisplatin (7.5 mg/kg body weight) with or without curcumin treatment (120 mg/kg body weight). Blood urea nitrogen (BUN), creatinine, albumin, tumour necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, IL-8, IL-10 expressions and histological changes were determined on the 5th day after cisplatin injection. Acute kidney damage was evident by increased BUN and creatinine levels. In addition, cisplatin showed a marked pro-inflammatory response as revealed by a significant increase in the tissue levels of TNF-α, IL-6, IL-8 and decrease in the IL-10 level. Pre-treatment of curcumin reduced cisplatin-induced nephrotoxicity which was clearly evident from the reduced BUN, creatinine, TNF-α, IL-6 and IL-8 levels and increased albumin and IL-10 levels. Additionally, these findings were also supported by histopathology of the kidneys. In contrast, post-treatment of curcumin failed to cut down the expression of inflammatory markers substantially and also neglected to increase the expression of IL-10. The disparity in the action of curcumin after pre- and post-treatment with cisplatin-induced nephrotoxicity was due to the inability of post-treatment to reduce TNF-α & IL-6, besides to show a concurrent rise in IL-10 expression in renal tissues.

Amniotic Fluid-Derived Mesenchymal Stem Cells Cut Short the Acuteness of Cisplatin-Induced Nephrotoxicity in Sprague-Dawley Rats

BACKGROUND AND OBJECTIVES

Cisplatin is a nephrotoxic chemotherapeutic agent. So, preventive measures worth to be evaluated. Human amniotic fluid stem cells (hAFSCs) in prevention or amelioration of cisplatin-induced acute kidney injury (AKI) in Sprague-Dawley rates have been tested.

METHODS

80 Sprague-Dawley rats (250~300 g) were used and divided into 4 major groups, 20 rats each. Group I: Saline-injected group. Group II: Cisplatin-injected group (5 mg/kg I.P). Group III: Cisplatin-injected and hAFSCs-treated group (5×10⁶ hAFSCs I.V. one day after cisplatin administration). Group IV: Cisplatin-injected and culture media-treated group. Each major group was further divided into 4 equal subgroups according to the timing of sacrifice; 4, 7, 11 and 30 days post-cisplatin injection. Renal function tests were done. Kidney tissue homogenate oxidative stress parameters malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione (GSH) were determined. Histopathological scoring systems for active injury, regenerative and chronic changes were analyzed separately.

RESULTS

hAFSCs characterization and differentiation was proved. Cisplatin injection resulted in a significant increase in serum creatinine and MDA and decrease in SOD, GSH and creatinine clearance. These changes were attenuated early by day 4 with the use of hAFSCs. Cisplatin injection induced tubular necrosis, atrophy, inflammatory cells infiltration and fibrosis. The use of hAFSCs was associated with significantly lowered injury score at day 4, 7, 11 and 30 with marked regenerative changes starting from day 4.

CONCLUSION

hAFSCs have both a protective and regenerative activities largely through an antioxidant activity. This activity cut short the acuteness of cisplatin nephrotoxicity.

Physalis alkekengi and Alhagi maurorum ameliorate the side effect of cisplatin-induced nephrotoxicity

Cisplatin is frequently being used for the treatment of different tumors, although the application of this agent is associated with nephrotoxicity. Here, we explored the antioxidant and anti-inflammatory activities of Physalis alkekengi and Alhagi maurorum; 400 mg kg(-1) per day P. alkekengi and 100 mg kg(-1) per day A. maurorum were administered in rats, orally for 10 days after a single dose of 7 mg kg(-1) intraperitoneal cisplatin. The concentrations of creatinine, urea-nitrogen, and relative and absolute excretion of sodium/potassium were evaluated before/after therapy. Levels of malondialdehyde (MDA) and ferric-reducing antioxidant power (FRAP) were measured to assess the oxidative stress induced by cisplatin. Moreover, tissues sections were used for histological analyses and evaluation of the degree of tissue damage. Cisplatin increased serum levels of creatinine and urea-nitrogen, relative/absolute excretion of sodium/potassium, and MDA, whereas decreased FRAP level. Interestingly, P. alkekengi or A. maurorum were able to reduce the level of the renal function markers as well as the levels of sodium/potassium. This effect was more pronounced by P. alkekengi. Moreover, cisplatin induced pathological damage in kidney, whereas treatment with these agents improved this condition. Our findings demonstrate the potential therapeutic impact of P. alkekengi and A. maurorum for improving cisplatin-induced nephrotoxicity, supporting further investigations on the novel potential clinical application of these agents for patients being treated with cisplatin to ameliorate cisplatin-induced nephrotoxicity.

Protective effect of mycophenolate mofetil against nephrotoxicity and hepatotoxicity induced by tacrolimus in Wistar rats

Tacrolimus (TAC), a calcineurin inhibitor (CNI), is clinically used as an immunosuppressive agent in the transplant recipient; however, the use of TAC is greatly limited by its nephrotoxicity and hepatotoxicity. Mycophenolate mofetil (MMF), an inhibitor of the purine synthesis, has been used in combination with many immunosuppressive drugs such as TAC. The association TAC/MMF was used in organ transplantation to increase the efficiency and reduce acute rejection rates, but the effects of MMF on TAC-induced kidney and liver injuries are still not well investigated. The aims of this study are to explore whether MMF co-administration with TAC has a renoprotective and hepatoprotective effect against TAC-induced renal and hepatic injuries and to check the implication of oxidative stress in the MMF's possible protective effect. Our results showed that MMF (at 50 mg kg(-1) body weight (b.w.)) restored creatinine, in addition to increased AST and ALT levels by TAC (at 60 mg kg(-1) b.w.). Furthermore, MMF decreased DNA damage induced by TAC in the kidney and liver of rats as assessed by comet assay. This renoprotective and hepatoprotective effect of MMF was associated with an antioxidant effect. In fact, MMF co-treatment with TAC decreased oxidative damage induced by TAC. It reduced malondialdehyde (MDA) and protein carbonyl (PC) levels as well as catalase and superoxide dismutase (SOD) activities. We conclude that the co-administration MMF with TAC protect liver and kidney against TAC toxicity via an antioxidant process.

Tacrolimus and mycophenolate mofetil associations

Gastrointestinal risk factors after organ transplantation are prevalent, due to the chronic use of immunosuppressant. The immunosuppressive drugs such as tacrolimus/mycophenolate mofetil (TAC/MMF) association are the most commonly used therapy. TAC and MMF have been implicated in gastrotoxicity, but their direct effects, alone and combined, on intestinal cells are not completely elucidated. This study investigated the effect of TAC and MMF alone and combined on human colon carcinoma cells. Our results demonstrated that TAC and MMF individually inhibit clearly cells proliferation, enhanced free radicals, lipid peroxidation production, induced DNA lesions and reduced mitochondrial membrane potential. In this study, we also showed that the two molecules TAC and MMF combined at high concentrations amplified the cell damage. Furthermore, the TAC (5 µM) prevented cell death induced by MMF (half maximal inhibitory concentration (IC50)). Also, MMF (50 µM) induced cytoprotection in HCT116 cells against TAC (IC50) toxicity. Our findings provide additional evidence that oxidative damage is the major contribution of TAC and MMF combined toxicities. In fact, MMF and TAC exert a gastroprotective effect by modulating reactive oxygen species production. These data underscore the pleiotropic effect of TAC and MMF on HCT116 cells that play a preventive and critical role on intestinal function.

Metabolomics in nephrotoxicity

Nephrotoxicity or renal toxicity can be a result of hemodynamic changes, direct injury to cells and tissue, inflammatory tissue injury, and/or obstruction of renal excretion. Nephrotoxicity is frequently induced by a wide spectrum of therapeutic drugs and environ mental pollutants. Knowledge of the complex molecular and pathophysiologic mechanisms leading to nephrotoxicity remains limited, in part, by research that historically focused on single or relatively few risk markers. As such, current kidney injury biomarkers are inadequate in terms of sensitivity and specificity. In contrast, metabolomics enables screening of a vast array of metabolites simultaneously using NMR and MS to assess their role in nephrotoxicity development and progression. A more comprehensive understanding of these biochemical pathways would also provide valuable insight to disease mechanisms critical for drug development and treatment.

Renal denervation restores the baroreflex control of renal sympathetic nerve activity and heart rate in Wistar-Kyoto rats with cisplatin-induced renal failure

AIM

There is evidence that in chronic renal failure, the sympathetic nervous system is activated. This study investigated the role of the renal innervation in suppressing high- and low-pressure baroreflex control of renal sympathetic nerve activity and heart rate in cisplatin-induced renal failure.

METHODS

Renal failure was induced using cisplatin (5 mg kg(-1) , i.p.) and the rats used 7 days later. Groups of rats were anaesthetized and prepared for measurement of renal sympathetic nerve activity and heart rate. Acute unilateral or bilateral renal denervation was performed, and renal sympathetic nerve activity and heart rate baroreflex gain curves were generated while the cardiopulmonary receptors were stimulated using an acute saline volume load.

RESULTS

Cisplatin administration reduced (P < 0.05) glomerular filtration rate by 27%, increased sodium fractional excretions fourfold, plasma creatinine and kidney index by 39 and 30% respectively, (all P < 0.05) compared with control rats. In the renal failure rats, baroreflex sensitivity for renal sympathetic nerve activity and heart rate was reduced (P < 0.05) by 29% and 27% (both P < 0.05) compared with control animals. Bilateral, but not unilateral, renal denervation restored baroreflex sensitivity to normal values. Volume expansion reduced (P < 0.05) renal sympathetic nerve activity by 34% in control rats, but remained unchanged in the renal failure rats. Unilateral and bilateral renal denervation progressively restored the volume expansion induced renal sympathoinhibition to control values.

CONCLUSION

These findings reveal a significant role of the renal sensory innervation in cisplatin-damaged kidneys which blunt the normal baroreflex control of renal sympathetic nerve activity.

Neuroimaging, biochemical and cellular evidence of protection by mycophenolate mofetil on middle cerebral artery occlusion induced injury in rats

Stroke is a major cause of mortality and disability worldwide. Presently, recombinant tissue plasminogen activator is the only approved drug for the management of acute ischemic stroke. However, it has limitations like narrow therapeutic window and increased risk of intracranial hemorrhage. In previous studies, immunosuppressive agents such as cyclosporine A and tacrolimus have shown neuroprotection by improving neurological functions and infarct volume in models of ischemic stroke. Therefore, the present study was designed to evaluate the effect of mycophenolate mofetil (MMF) on the cerebral ischemic injury in the middle cerebral artery occlusion (MCAo) model in rats. MCAo was carried out in male Wistar rats by inserting an intraluminal thread. One hour after MCAo, the animals were treated with MMF (50, 100, 200mg/kg, i.p.). Reperfusion was done after 2h of occlusion. Thirty minutes after reperfusion, animals were subjected to diffusion-weighted magnetic resonance imaging for assessment of neuroprotective effect of MMF. Twenty four hours after MCAo, motor performance was assessed and the animals were euthanized for estimation of brain malondialdehyde, glutathione, myeloperoxidase and nitric oxide levels. The effect of MMF on apoptosis was also evaluated. MMF significantly attenuated the percent infarct area, apparent diffusion coefficient and signal intensity as compared to a vehicle treated group. Treatment with MMF prevented the motor impairment and significantly reversed the changes in levels of malondialdehyde, glutathione, myeloperoxidase and nitric oxide. MMF treatment significantly reduced the apoptosis. Data of the present study indicate neuroprotective effect of MMF in the experimental model of ischemic stroke.

Evidence of an anti-inflammatory effect of mycophenolate mofetil in a murine model of pleurisy

A promising therapeutic approach to reducing inflammation is to inhibit the production of proinflammatory cytokines (e.g., tumor necrosis factor alpha [TNF-α], interleukin 1 beta [IL-1β], vascular endothelial growth factor alpha (VEGF-α), and, as shown more recently, interleukin-17 [IL-17]). In the present study, the authors have demonstrated the anti-inflammatory effects of mycophenolate mofetil (MMF) in in vivo experiments and have investigated the mechanism of action underlying those effects. Oral administration of MMF significantly inhibited leukocyte influx during the first (4 hours) and second (48 hours) phases of inflammation in a mouse model of pleurisy caused by carrageenan (P < .01). As expected, MMF suppressed protein levels of TNF-α, IL-1β, VEGF-α, and IL-17A (P < .01). This inhibitory effect was due to down-regulation of mRNA expression for these proinflammatory cytokines (P < .01). These results provide evidence of MMF-mediated inhibition of proinflammatory cytokines, and these anti-inflammatory effects are assumed to result mainly from the inhibition of the synthesis and release of TNF-α, IL-1β, VEGF-α, and IL-17A from activated leukocytes. These findings suggest that MMF might be an applicable therapeutic in the regulation of the inflammatory response-a response in which the humoral system plays a pivotal role.

Antioxidant effects of mycophenolate mofetil in a murine pleurisy model

Generation of oxidative stress induced by reactive oxygen species (ROS) and nitrogen (RNS) is believed to be a primary factor in the etiology of various inflammatory diseases. Although, the process of generation of oxygen species is a physiological event, in the inflammatory process this event is increased and produces large amounts of reactive species that leads to lipid peroxidation and to cell death. Mycophenolate mofetil (MMF) is a drug effective in protecting against chronic allograft failure and recently was introduced as an alternative for the treatment of various inflammatory diseases such as glomerulopathies, systemic lupus erythematosus and systemic vasculitis. Based on studies of the anti-inflammatory effect of MMF the aim of this study was to evaluate the effects of MMF on the inhibition of leukocytes and exudation, as well as myeloperoxidase and some antioxidant enzyme activities using carrageenan-induced pleurisy in mice. Our results showed that MMF significantly decreased leukocyte influx (P<0.01), exudation (P<0.01), superoxide dismutase (P<0.05), catalase (P<0.05), glutathione peroxidase (P<0.01), glutathione S-transferase (P<0.01) activities, levels of lipid peroxidation (P<0.05), as well as myeloperoxidase activity (P<0.05) on both phases (4h and 48h) of the inflammatory response induced by carrageenan into the mice pleural cavity. In conclusion, the anti-inflammatory effect of MMF may be, at least in part, via inhibition of ROS and/or NRS overgeneration, and consequently, attenuating the related oxidative stress.

Experimental models for nephropathy

Nephropathy is a leading cause of morbidity and mortality and its prevalence is continuously increasing in industrialised nations. Nephropathy is characterised to varying degrees by nodular glomerulosclerosis, glomerular basement membrane thickness and mesangial expansion, leading to a decline in glomerular filtration rate, persistent elevated albuminuria, elevated arterial blood pressure and fluid retention. Hyperglycaemia, hyperlipidaemia and hypertension are considered to be the major risk factors implicated in the progression of nephropathy.Various signalling systems, such as vasoconstrictor peptides, inflammatory mediators, growth factors and adhesion molecules, are involved in the pathogenesis of nephropathy.At present, no promising therapy is available to treat patients with nephropathy due to lack of understanding of signalling culprits involved in the pathogenesis of nephropathy. Animal models are being developed to better understand the disease pathogenesis and develop drugs for nephropathy. In the present review, we have discussed various animal models for nephropathy, which may open vistas for developing new drugs to treat nephropathy.

Influence of combined hypertension and renal failure on functional alpha(1)-adrenoceptor subtypes in the rat kidney

BACKGROUND AND PURPOSE

This study investigated whether the alpha(1)-adrenoceptor responsiveness of the renal vasculature was altered in the state of hypertension combined with renal failure.

EXPERIMENTAL APPROACH

Male spontaneously hypertensive rats (SHR) received cisplatin (5 mg kg(-1) i.p.) to induce renal failure. Seven days later, the rats were anaesthetized and the reductions in renal blood flow (RBF) to electrical renal nerve stimulation (RNS) and intrarenal administration of three adrenoceptor agonists (noradrenaline, phenylephrine and methoxamine) were determined before and after amlodipine, 5-methylurapidil, chloroethylclonidine or BMY 7378.

KEY RESULTS

In renal failure SHR (RFSHR), RBF and creatinine clearance were significantly reduced (approximately 70%), while urine output and fractional sodium excretion were four and twenty-fold higher, respectively, compared to SHR. Vasoconstrictions induced by RNS or the adrenoceptor agonists were greater in RFSHR than SHR, and these responses were blunted by 5-methylurapidil, BMY 7378 and amlodipine in the SHR, while chloroethylclonidine had no effect. In the RFSHR, all renal vasoconstrictions were reduced by amlodipine and BMY 7378 but 5-methylurapidil attenuated those caused by RNS, noradrenaline and methoxamine while those to phenylephrine were enhanced. Chloroethylclonidine potentiated renal vasoconstrictor responses to methoxamine and phenylephrine but not RNS or noradrenaline in RFSHR.

CONCLUSIONS AND IMPLICATIONS

These findings suggest alpha(1A)- and alpha(1D)-adrenoceptors mediated the renal vasoconstrictor responses in SHR and RFSHR. In the RFSHR, other alpha(1)-adrenoceptor subtypes, for example, alpha(1B)-adrenoceptors appeared to play a greater role.

Reversal of cisplatin-induced carnitine deficiency and energy starvation by propionyl-L-carnitine in rat kidney tissues

1. The present study examined whether propionyl-L-carnitine (PLC) could prevent the development of cisplatin (CDDP)-induced acute renal failure in rats. 2. Forty adult male Wistar albino rats were divided into four groups. Rats in the first group were injected daily with normal saline (2.5 mL/kg, i.p.) for 10 consecutive days, whereas the second group received PLC (250 mg/kg, i.p.) for 10 consecutive days. Animals in the third group were injected daily with normal saline for 5 consecutive days before and after a single dose of CDDP (7 mg/kg, i.p.). Rats in the fourth group received a combination of PLC (250 mg/kg, i.p.) for 5 consecutive days before and after a single dose of CDDP (7 mg/kg, i.p.). On Day 6 following CDDP treatment, animals were killed and serum and kidneys were isolated for analysis. 3. Injection of CDDP resulted in a significant increase in serum creatinine, blood urea nitrogen (BUN), thiobarbituric acid-reactive substances (TBARS) and total nitrate/nitrite (NO(x)), as well as a significant decrease in reduced glutathione (GSH), total carnitine, ATP and ATP/ADP in kidney tissues. 4. Administration of PLC significantly attenuated the nephrotoxic effects of CDDP, manifested as normalization of the CDDP-induced increase in serum creatinine, BUN, TBARS and NO(x) and the CDDP-induced decrease in total carnitine, GSH, ATP and ATP/ADP in kidney tissues. 5. Histopathological examination of kidney tissues from CDDP-treated rats showed severe nephrotoxicity, in which 50-75% of glomeruli and renal tubules exhibited massive degenerative changes. Interestingly, administration of PLC to CDDP-treated rats resulted in a significant improvement in glomeruli and renal tubules, in which less than 25% of glomeruli and renal tubules exhibited focal necrosis. 6. Data from the present study suggest that PLC prevents the development of CDDP-induced acute renal injury by a mechanism related, at least in part, to the ability of PLC to increase intracellular carnitine content, with a consequent improvement in mitochondrial oxidative phosphorylation and energy production, as well as its ability to decrease oxidative stress. This will open new perspectives for the use of PLC in the treatment of renal diseases associated with or secondary to carnitine deficiency.

Alpha1B-adrenoceptors mediate adrenergically-induced renal vasoconstrictions in rats with renal impairment

AIM

This study examined whether alpha1B-adrenoceptors are involved in mediating adrenergically-induced renal vasoconstrictor responses in rats with pathophysiological and normal physiological states.

METHODS

Male Wistar Kyoto and spontaneously hypertensive rats were induced with acute renal failure or experimental early diabetic nephropathy by cisplatin or streptozotocin, respectively. Cisplatin-induced renal failure was confirmed by impaired renal function and pronounced tubular damage. Experimental early diabetic nephropathy was confirmed by hyperglycemia, changes in physiological parameters, and renal function. The hemodynamic study was conducted on anesthetized rats after 7 d of cisplatin (renal failure) and 4 weeks of streptozotocin (experimental early diabetic nephropathy).

RESULTS

In the rats with renal failure and experimental early diabetic nephropathy, there were marked reductions in their baseline renal blood flow (P<0.01). The baseline mean arterial blood pressure was either unaltered or lower (all P>0.05) in the renal failure and experimental early diabetic nephropathy rats, respectively, as compared to their non-renal failure and non-diabetic nephropathy controls. In the rats with renal impairment, chloroethylclonidine caused either accentuation or attenuation (all P<0.01) of the renal vasoconstrictor responses elicited by the adrenergic stimuli. However, in the non-renal failure and in the non-diabetic nephropathy rats, chloroethylclonidine did not cause any alteration in such responses (P>0.05).

CONCLUSION

This study demonstrated the presence of functional alpha1B-adrenoceptors that mediated the adrenergically-induced renal vasoconstrictions in rats with renal impairment, but not in rats with normal renal function.

Effect of curcumin on inflammation and oxidative stress in cisplatin-induced experimental nephrotoxicity

Nephrotoxicity is a major complication and a dose limiting factor for cisplatin therapy. Recent evidence suggests that inflammation and oxidative stress may contribute to the pathogenesis of cisplatin-induced acute renal failure. Curcumin is claimed to be a potent anti-inflammatory and antioxidant agent. The present study was performed to explore the effect of curcumin against cisplatin-induced experimental nephrotoxicity. Curcumin in the dosages of 15, 30, and 60 mg kg(-1) was administered 2 days before and 3 days after cisplatin administration. Renal injury was assessed by measuring serum creatinine, blood urea nitrogen, creatinine, urea clearance, and serum nitrite levels. Renal oxidative stress was assessed by determining renal malondialdehyde levels, reduced glutathione levels and enzymatic activities of superoxide dismutase and catalase. Systemic inflammation was assessed by tumor necrosis factor-alpha (TNF-alpha) levels. A single dose of cisplatin resulted in marked inflammation (486% rise in TNF-alpha level) and oxidative stress and significantly deranged renal functions as well as renal morphology. The serum TNF-alpha level was markedly reduced in curcumin-treated rats. Curcumin treatment significantly and dose-dependently restored renal function, reduced lipid peroxidation, and enhanced the levels of reduced glutathione and activities of superoxide dismutase and catalase. The present study demonstrates that curcumin has a protective effect on cisplatin-induced experimental nephrotoxicity, and this effect is attributed to its direct anti-inflammatory and strong antioxidant profile. Hence, curcumin has a strong potential to be used as a therapeutic adjuvant in cisplatin nephrotoxicity.

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.