Renal Failure In Rats Research Articles

Pyridoxamine ameliorates the effects of advanced glycation end products on subtotal nephrectomy induced chronic renal failure rats

Advanced glycation end products (AGEs) contribute to the pathogenesis of renal diseases and have become a new therapeutic target for treatment. Chronic renal failure (CRF) is the end-stage of chronic renal diseases and highly associated with increased incidence in cardiovascular complications, however, some of the pathogenesis has not yet been fully clarified. This study was designed to evaluate the therapeutic or preventive potential of pyridoxamine (PM) against CRF in a 5/6 subtotal nephrectomy rat model. Significant and beneficial contributions to body weight, cardiovascular parameters, clearances of creatinine and BUN and AGEs reduction were observed in CRF rats receiving PM for 8weeks. PM supplementation might be considered as one of pharmacological strategies for preventing AGE-related pathologies and early stages of renal damage. Prospective trials are needed to elucidate a potential role for PM in adjunctive therapy and to confirm the adequate amount on cardiovascular and renal outcomes in CRF.

Cytotoxic and renoprotective flavonoid glycosides from Horwoodia dicksoniae

Three flavonoid glycosides and one aglycone were isolated from the ethanol extract (EE) ofHorwoodia dicksoniae (Brassicaceae), for the first time, and their structures were established from negative ESI-MS, 1H-, 13C-NMR and DEPT as luteolin 7-O-β-D-glucopyranoside (1), luteolin 6-C-β-D-galactopyranoside (2), apigenin 6-C-β-D-galactopyranoside (3) and luteolin (4). The SRB cytotoxicity assay was used to investigate the antitumor activity of the EE, Compounds 1, 2 and 4. Compound 1 showed the highest cytotoxic activity against the three human cell lines, including HEP-G2, HCT-116 and MCF-7 (IC50 = 10.7, 9.3 and 9.9 µg/ml, respectively), compared with doxorubicin as reference drug. Compound 4 showed selective antitumor activity against the colon cell line (IC50 = 9.5 µg/ml). The present investigation also demonstrates the protective effect of Compounds 1, 2 and 4 with strong antioxidant potential, in glycerol-induced myoglobinuric acute renal failure in rats. Moreover, all tested compounds separately attenuated renal dysfunction, and restored the oxidant balance by decreasing renal MDA levels, increasing the activity of the depleted renal antioxidant enzymes, and the non enzymatic antioxidant GSH. They also, decreased the elevated serum inflammatory marker (TNF-α), and ameliorated apoptotic kidney damage by reduction in caspase-3 activity. Taken together, 1 was found to be the most biologically active compound. Key words: Rhabdomyolysis, glycerol, acute renal failure, flavone glycosides, cytotoxicity.

Therapeutic potential of 7,8-dimethoxycoumarin on cisplatin- and ischemia/reperfusion injury-induced acute renal failure in rats

This study was designed to investigate the role of 7,8-dimethoxycoumarin on cisplatin- and ischemia/reperfusion (I/R)-induced acute renal failure in rats. Acute renal failure was induced in rats by administration of a single dose of cisplatin (CP) (6 mg/kg, intraperitoneally on day 6) and occlusion of the left renal artery for 45 min (I) and opened for the next 24 h (R). The drug samples of 7,8-dimethoxycoumarin (DMC, 50, 75, and 100 mg/kg) and cyclosporin A (50 μM/kg) were administered orally for six consecutive days. Administration of a single dose of cisplatin and I/R event has significantly raised blood urea nitrogen and creatinine, N-acetyl beta-D: -glucosaminidase, and thiobarbituric acid reactive substances but decreased FrNa, creatinine clearance, reduced glutathione (GSH), mitochondrial cytochrome c oxidase, and adenosine triphosphate levels. Further, pretreatment of DMC (50, 75, and 100 mg/kg, p.o., for six consecutive days) has ameliorated the CP- and I/R-induced biochemical and histopathological changes in a dose-dependent manner. Furthermore, 75 and 100 mg/kg of 7,8-dimethoxycoumarin has shown to possess the significant renoprotective effect similar to that of the cyclosporin A-treated group which served as positive control. Based on the results of the present study, it has been concluded that 7,8-dimethoxycoumarin protects the kidney against the CP and I/R injury via antioxidant, anti-inflammatory, and inactivation of mitochondrial permeability transition pore opening.

Effect of gum Arabic on oxidative stress and inflammation in adenine–induced chronic renal failure in rats

Inflammation and oxidative stress are known to be involved in the pathogenesis of chronic kidney disease in humans, and in surgically‐induced chronic renal failure (CRF) in rats. Evidence for the involvement of these processes in adenine‐induced CRF in rats is lacking. The aim of this work was to study the role of inflammation and oxidative stress in adenine‐induced CRF, and the effect thereon of the purported nephroprotective agent gum arabic (GA). Rats were divided into four groups and treated for 4 weeks as follows: control, adenine in the feed (0.75%, w/w), GA in drinking water (15%,w/v) and adenine + GA, as before. Urine, blood and kidneys were collected from the rats at the end of the treatment for analysis of conventional renal function tests (plasma creatinine and urea concentration and urinary NAG activity). In addition, the concentrations of several pro‐inflammatory cytokines and indices of oxidative stress, renal apoptosis, superoxide formation and DNA double strand break frequency detected with immunohistochemistry for γ‐H2AX were also conducted in the kidney tissue, plasma and urine. Adenine (0.75% in the feed for 4 weeks) caused significant increases (P < 0.001) in the concentrations of urea and creatinine in plasma, significantly decreased the creatinine clearance (P < 0.01) and induced significant increases in the concentration of the measured inflammatory mediators. Treatment with GA significantly ameliorated these actions, suggesting that the mechanism of the reported salutary effect of GA in adenine‐induced CRF is associated with mitigation of the adenine‐induced inflammation and generation of free radicals.

COMPARSION BETWEEN RENOPROTECTIVE EFFECTS OF CARVEDILOL AND LISINOPRIL IN L-NAME-TREATED RATS

Aim The present study compared the renoprotective effects of curative and prophylactic doses of carvedilol and lisinopril in L-NAME treated rats. Material and methods Rats were divided into seven groups: the first and second (normal control and hypertensive control) groups received distilled water and L-NAME (L-nitro argentine methyl ester, 50 mg/kg per day), respectively, for eight weeks. The third and fourth groups received L–NAME (50mg/kg per day) in combination with a prophylactic dose of carvedilol (15mg/kg per day) or lisinopril (20mg/kg per day), respectively, for eight weeks. The fifth, sixth and seventh groups received L-NAME (50mg/kg per day) for eight weeks, followed by curative doses of carvedilol (30mg/kg per day), lisinopril (40mg/kg per day) or carvedilol (15mg/kg per day) in combination with lisinopril (20mg/kg per day), respectively, for five weeks. The drugs were administered by gastric gavage. Results During prophylactic therapy, carvedilol and lisinopril decreased L-NAME induced rise in systolic blood pressure (SBP) and serum creatinine levels. Furthermore, both drugs improved microalbuminuria and renal histopathological changes and increased serum nitric oxide (sNO). During curative therapy, carvedilol improved microalbuminuria and renal histopathological changes. lisinopril or the combination of carvedilol and lisinopril improved all L-NAME induced changes. The combination improved renal histopathological changes more significantly than each individual drug. Conclusion carvedilol and lisinopril have prophylactic and curative renoprotective effects in L-NAME treated rats. Carvedilol has similar effectiveness as the converting enzyme inhibitor, lisinopril, in reducing the hypertension, proteinuria and glomerulosclerosis associated with L-NAME induced chronic hypertensive renal failure in rats making chronic renal disease as a therapeutic target for this drug. Moreover, a combination of both drugs at half the therapeutic doses significantly ameliorated hypertension-induced renal damage and improved renal functions, indicating the role of this low-dose combination as an effective therapeutic option if a multi-anti-hypertensive regimen is desirable.

Preventive effects of hyperbaric oxygen treatment on glycerol-induced myoglobinuric acute renal failure in rats

Myoglobinuric acute renal failure (ARF) is a uremic syndrome caused by traumatic or non-traumatic skeletal muscle breakdown and intracellular elements that are released into the bloodstream. We hypothesized that hyperbaric oxygen (HBO) therapy could be beneficial in the treatment of myoglobinuric ARF caused by rhabdomyolysis. A total of 32 rats were used in the study. The rats were divided into four groups: control, control+hyperbaric oxygen (control+HBO), ARF, and ARF+hyperbaric oxygen (ARF+HBO). Glycerol (8 ml/kg) was injected into the hind legs of each of the rats in ARF and ARF+HBO groups. 2.5 atmospheric absolute HBO was applied to the rats in the control+HBO and ARF+HBO groups for 90 min on two consecutive days. Plasma urea, creatinine, sodium, potassium, calcium, aspartate aminotransferase, alanine aminotransferase, lactic dehydrogenase, creatinine kinase and urine creatinine and sodium were examined. Creatinine clearance and fractional sodium excretion could then be calculated. Superoxide dismutase, catalase, glutathione and malondialdehyde (MDA) levels were assessed in renal tissue. Tissue samples were evaluated by Hematoxylin-eosin, PCNA and TUNEL staining histopathologically. MDA levels were found to be significantly decreased whereas SOD and CAT were twofold higher in the ARF+HBO group compared to the ARF group. Renal function tests were ameliorated by HBO therapy. Semiquantitative evaluation of histopathological findings indicated that necrosis and cast formation was decreased by HBO therapy and TUNEL staining showed that apoptosis was inhibited. PCNA staining showed that HBO therapy did not increase regeneration. Ultimately, we conclude that, in accordance with our hypothesis, HBO could be beneficial in the treatment of myoglobinuric ARF.

Repeated Topical Application of para-Phenylenediamine Induces Renal Histopathological Changes in Rats.

Hemolytic anemia and rhabdomyolysis have been often reported to be an adverse effect of drug- and chemical-induced toxicity both in experimental and real-life scenario. para-Phenylenediamine (PPD) is a derivative of para-nitroaniline and has been found as an ingredient of almost all hair dye formulations in varying concentrations from 2% to 4% w/v. Earlier studies have reported that the accidental oral ingestion of PPD in humans can lead to acute renal failure because of rhabdomyolysis. In the present investigation, we have tested the chronic topical application of PPD and its effect on the renal histology of Sprague-Dawley rats. The experiment provides clear evidence that topically applied PPD induces hemolytic anemia as evident from the decrease in the total RBC count, packed cell volume, and hemoglobin content apart from rhabdomyolysis which subsequently causes acute renal failure in rats.

Recombinant human erythropoietin reduces rhabdomyolysis-induced acute renal failure in rats

BackgroundRhabdomyolysis is one of the causes of acute renal failure. Erythropoietin (EPO) has been found to interact with its receptor (EPO-R) expressed in a large variety of non-haematopoietic tissues to induce a range of pleiotropic cytoprotective actions. In this study, we used recombinant human erythropoietin (rhEPO) to study the effects on the glycerol-induced rhabdomyolysis with acute renal failure in rats. MethodsTwenty-four rats were divided into three groups as glycerol group, glycerol+EPO group and normal saline+EPO group. Rhabdomyolysis was induced by intramuscular injection of 10mlkg−1 50% glycerol in rats. Ten minutes later, the rats received an intravenous injection of rhEPO (300Ukg−1). Biochemical substances, including haemoglobin, blood urea nitrogen (BUN), creatinine (Cre), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) and creatine phosphokinase (CPK), were measured at 0, 1, 3, 6, 9, 12, 18, 24 and 48h. Rats were sacrificed 48h later after glycerol administration and the kidneys were removed immediately for pathology and immunohistochemistry (IHC). ResultsIntramuscular injection of glycerol significantly increased blood BUN, Cre, GOT, GPT and CPK levels and induced severe histopathologic damage in the kidneys. Nuclear factor-κB (NF-κB) and inducible nitric oxide synthase (iNOS) were increased and E-cadherin was decreased after glycerol administration, as detected by IHC in the kidneys. Post-treatment with rhEPO decreased blood BUN, Cre, GOT, GPT and CPK levels, decreased markers of kidney injury and suppressed the release of NF-κB and iNOS after rhabdomyolysis. ConclusionTreatment with rhEPO suppressed the activities of NF-κB and iNOS, decreased BUN, Cre, GOT, GPT and CPK levels, and decreased the markers of kidney injury after rhabdomyolysis. These actions ameliorated rhabdomyolysis-induced acute renal failure in rats.

Effects of the anti-ulcer agents ecabet sodium, cimetidine and sucralfate on acetylsalicylic acid-induced gastric mucosal damage deteriorated by renal failure in rats.

Renal failure including post-renal transplantation increases the susceptibility of the upper gastrointestinal mucosa to injury. The aim of this study was to confirm the influence of renal failure on gastric mucosal barrier and the protective effect of various anti-ulcer agents in rats. Renal failure (RF) was induced by 45-min left renal artery clamping and right-uninephrectomy. Four days after surgery, gastric mucosal lesions were induced by intragastric administration of acetylsalicylic acid (ASA, CAS 50-78-2) (100 mg/kg). Anti-ulcer agents were given orally 30 min before ASA administration. RF induced moderate gastric mucosal damages, but significantly worsened the ASA-induced gastric lesions. Ecabet sodium (CAS 86408-72-2) and cimetidine (CAS 51481-61-9) significantly inhibited ASA-induced gastric lesions in RF rats, whereas sucralfate (CAS 54182-58-0) tended to inhibit it. ASA and all of these anti-ulcer agents had no effect on the serum creatinine and blood urea nitrogen levels increased by RF. The gastric mucosa of RF rats is more susceptible to damage induced by ASA. Ecabet and cimetidine potently inhibited gastric lesions in RF rats suggesting its utility for the gastric mucosal damage in patients with RF including post-renal transplant.

Pharmacokinetics Characterization of Liposomal Amphotericin B: Investigation of Clearance Process and Drug Interaction Potential

AmBisome, a liposomal formulation of amphotericin B (CAS 1397-89-3, L-AMB), shows different pharmacokinetics from the conventional formulation, amphotericin B deoxycholate (D-AMB). To characterize the clearance process of L-AMB, the form in which it exists in rat plasma, pharmacokinetics in hepatic or renal failure rats, cellular distribution in rat liver, and placental and milk transfer in rat were investigated. Furthermore, to predict the drug-drug interaction, in vitro metabolism of amphotericin B (AMB) by rat, dog and human liver S9 fraction, and effects of L-AMB on drug-metabolizing enzyme systems were investigated. L-AMB was found to exist stably as a liposomal form in rat plasma without any notable transfer to milk or fetus in rats. After administration to hepatic failure rats, the CLtot of AMB decreased to 1/4 and the Vdss decreased to 1/8 compared with the control rat case. In contrast, after administration to renal failure rats, plasma AUC of AMB did not significantly change compared with sham-operated rats. These data suggest that hepatic clearance is the main determinant of the CLtot for L-AMB. In rat liver, L-AMB was distributed mainly to non-parenchymal cells. In the in vitro metabolism study using liver S9 fraction, no metabolite peaks were observed. After repeated administration of L-AMB to rats, there was no change in parameters related to the drug-metabolising enzyme system in liver microsomes. These data demonstrate that clinically significant metabolism-based drug interaction with L-AMB should be less likely.

Altered disposition of drugs in acute renal failure rat models: drug development strategies and perspectives

In the evolving paradigm of drug development it is a reasonable strategy to avoid and/or anticipate potential risks in drug development for select drugs by performing in vitro and/or preclinical studies in appropriate animal models. The availability of acute renal failure (ARF) rat models provides an opportunity to explore the pharmacokinetic disposition of drugs and associated metabolites in conditions that mimic the pathophysiology of the disease in humans. Such studies may help in drug(s) selection for development, differentiating certain drug classes, and/or arriving at a dose strategy decision in the clinic. Scores of compounds, belonging to various therapeutic areas, have undergone pharmacokinetic investigations in ARF models induced by uranyl nitrate (CAS 10102-06-4), glycerol (CAS 56-81-5), cisplatin (CAS 15663-27-1) or gentamicin (CAS 1403-66-3) in rats. The published pharmacokinetic disposition data has unequivocally suggested that ARF conditions leads to decreased renal elimination of the drug and associated metabolites; however, the influence on the overall body clearance is dependent on the propensity of the contribution of renal versus non-renal mechanisms of elimination. In the case studies assembled for this review, 52.5% of the drugs showed an increased drug exposure, 35% of the drugs showed a decreased drug exposure and 12.5% of the drugs showed no altered exposure, in ARF rat models relative to control rats. Interestingly, ARF can have an overall impact on drug absorption, distribution, metabolism, local transport and biliary excretion. Hence, the overall pharmacokinetic disposition may have to be interpreted with caution during ARF since there is the potential for competiting pathways to co-exist. For instance, due to reduced renal elimination as a result of kidney insult caused by ARF, compensatory biliary excretion mechanism may occur. Alternatively, intestinal and/or hepatic enzymatic expression level may go up to facilitate enhanced metabolism. However, there may be instances where uraemic toxins floating in the circulation may block the metabolism and/ or may also retard the absorption process. This review covers: 1) an illustration of a number of case studies providing tabulated information on the key altered pharmacokinetic parameters observed in ARF and the hypothesized mechanistic explanation; 2) a comprehensive description of altered absorption, distribution, metabolism, excretion and efflux transport related changes observed during ARF; 3) a general framework for drug development strategies and 4) a succinct discussion on the overall perspectives of the applicability of ARF rat models.

Serum metabonomics study of adenine-induced chronic renal failure in rats by ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

An ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC Q-TOF MS) metabonomics approach was employed to study the serum metabolic profiling of adenine-induced chronic renal failure (CRF) rats. Acquired data were subjected to principal component analysis (PCA) for differentiating the CRF and the normal control groups. Potential biomarkers were screened by using S-plot and were identified by the accurate mass, isotopic pattern and MS/MS fragments information obtained from UPLC Q-TOF MS analysis. Significant differences in the serum level of creatinine, amino acids and LysoPCs were observed, indicating the perturbations of amino acid metabolism and phospholipid metabolism in adenine-induced CRF rats. This research proved that metabonomics is a promising tool for disease research.

Effect of Human Umbilical Cord Blood Progenitor Cells Versus Mononuclear Cells on Acute Renal Failure Rat Model

Acute renal failure (ARF) resulting from ischemic or toxic insults remains a major health care problem because of its grave prognosis and the limited effectiveness of available treatment modalities. Current treatment options for ARF are limited to supportive measures and preventive strategies, none of which have been definitively shown to alter mortality. To assess the ability of human umbilical cord blood CD34(+) (HUCB CD34(+)) cells and mononuclear (HUCB MNC) cells to improve renal function of nephrotoxic kidney. ARF was induced in 30 rats by glycerol. After 24 hours, ARF was confirmed by increased blood urea nitrogen (BUN), serum urea and creatinine levels. The rats were divided into 3 groups, group one included 10 rats treated with HUCB CD34(+) cells, group two included 10 rats treated with HUCB MNC and group three included 10 rats treated with normal saline. Five rats were included in the study as a normal control group. Serial measurement of BUN, serum urea and creatinine levels were done every three days throughout the study. To proof homing of HUCB CD34(+) into renal tissue, Y chromosome detection in renal tissue was carried out using Real time polymerase chain reaction (PCR) technique. Four days after the therapy, the renal function of CD34(+) and MNC treated rats improved in comparison to saline treated rats. After 2 weeks of therapy and at the end of the study (28 days), ANOVA test revealed that, there was significant difference between the four studied groups (P=.000). Y chromosomes were detected in kidneys of CD34(+) treated rats and MNC treated rats. HUCB CD34(+) cells and HUCB MNC improve renal function of nephrotoxic kidney with superiority to the HUCB MNC.

Asymmetric dimethylarginine may mediate increased heat pain threshold in experimental chronic kidney disease

Thermal sensitivity in uraemia is decreased. Non-selective synthetic nitric oxide synthase (NOS) inhibitors significantly attenuate thermal hyperalgesia in preclinical models. The aim of our study was to evaluate the effect of experimental uraemia, which is associated with an increase of the endogenous NOS inhibitor asymmetric dimethylarginine (ADMA), on thermal sensitivity in rats. Furthermore, we intended to study the effect of chronic ADMA infusion alone on thermal sensitivity. Male Sprague-Dawley rats (n = 54), 10 weeks old, weight 370-430 g, were randomly assigned to three groups receiving either (i) isotonic saline or (ii) ADMA via osmotic mini pumps or (iii) underwent 5/6 nephrectomy (Nx). After 14 days, 50% of all animals from all groups underwent thermal sensitivity testing and terminal blood draw. After 28 days, the remaining animals underwent the same procedures. Thermal sensitivity examination was performed by the hot-plate test, measuring time from heat exposition to first paw licking or jumping of the animal. While the median [interquartile range] latency time between heat exposition to first paw licking or jumping of the animal in the NaCl infusion group remained unchanged between Day 14 (8.4 [6.75-11.50] s) and Day 28 (7.35 [6.10-7.90] s) both, ADMA infusion and 5/6 nephrectomy tended to increase the thermal pain threshold at Day 14 (9.25 [6.55-12.18] s) and (9.50 [5.8 ± 11.0] s), respectively, compared to NaCl on Day 14 (8.4 [6.75-11.50] s). This difference became statistical significant at Day 28 where the median latency time in the ADMA group (13.10 [11.85-15.95] s) and in the 5/6 Nx group (13.50 [10.85-17.55] s) were significantly higher than in the NaCl group (7.35 [6.10-7.90] s). Induction of progressive renal failure in rats by 5/6 nephrectomy, which is accompanied by a marked increase of the serum levels of the endogenous NOS inhibitor ADMA, leads to a significantly increased heat pain threshold at 28 days. The sole infusion of ADMA into healthy rats leads to the same increase in heat pain threshold.

ENOS gene delivery prevents hypertension and reduces renal failure and injury in rats with reduced renal mass

Impaired nitric oxide (NO) release in chronic renal failure has been implicated in the pathogenesis of hypertension and the progression of renal insufficiency. We investigated whether gene delivery of the endothelial NO synthase (eNOS) improves NO release and reduces blood pressure and renal failure and injury in rats with reduced renal mass. Renal failure was induced by renal artery branches ligation. Two weeks later, rats with renal failure were divided into three groups and received an intravenous injection of the vehicle or the adenovirus that expresses eNOS or β-galactosidase (β-gal). Systolic blood pressure, renal parameters and histopathology were assessed at Week 4 after gene delivery. At the end of the study, systolic blood pressures, serum creatinine, proteinuria, urinary endothelin-1 (ET-1) excretion and renal cortex ET-1 levels were increased, whereas plasma and urine NO(2)/NO(3) were reduced in renal failure rats as compared to normal controls. Renal injury comprised blood vessel media hypertrophy, focal and segmental glomerular sclerosis, tubular atrophy and interstitial fibrosis. Gene delivery of eNOS, but not β-gal, prevented an increase in systolic blood pressure and proteinuria, and a reduction in plasma and urine NO(2)/NO(3). eNOS gene delivery also reduced a rise in serum creatinine, urinary ET-1 excretion and renal cortex ET-1 levels, and the renal vascular, glomerular and tubular injury. This study indicates that eNOS gene delivery in rats with renal failure improves NO release, which likely prevents the aggravation of hypertension and slows down the progression of renal failure and injury.

Characterization of bioactive compounds and ameliorative effects of Ceratonia siliqua leaf extract against CCl4 induced hepatic oxidative damage and renal failure in rats

Ceratonia siliqua is a typical Mediterranean plant, mainly used in food and Tunisian traditional folk medicine. Among the tested extracts, the ethyl acetate fraction (EACs) exhibited the highest total phenolic and flavonoids content. The antioxidant activity in vitro systems showed a more significant potent free radical scavenging activity of this extract than other analysis fractions. The HPLC finger print of EACs active extract showed the presence of six phenolic compounds. The in vivo results showed that oral administration of CCl4 enhanced levels of hepatic and renal markers (ALT, AST, ALP, LDH, γ-GT, urea and creatinine) in the serum of experimental animals. It also increased the oxidative stress markers resulting in increased levels of the lipid peroxidation with a concomitant decrease in the levels of enzymatic antioxidants (SOD, CAT, GPx) in both liver and kidney. The pre-treatment of experimental rats with 250mg/kg (BW) of the EACs, by intraperitoneal injection for 8days, prevented CCl4 induced disorders in the levels of hepatic and kidney markers. The biochemical changes were in accordance with histopathological observations suggesting a marked hepatoprotective and nephroprotective effect of the EACs extract.

Acquired resistance to rechallenge injury in rats that recovered from mild renal damage induced by uranyl acetate: accelerated proliferation and hepatocyte growth factor/c-Met axis

Rats that recovered from mild proximal tubule (PT) injury without renal dysfunction by subtoxic insult, developed partial resistance to subsequent nephrotoxic insult. This partial resistance was associated with reduced renal dysfunction and accelerated PT cell proliferation compared with vehicle treatment as the first insult. Here we assessed the role and potential mechanisms of accelerated PT proliferation in this acquired resistance model. Rats at 14days after recovering from prior mild renal damage induced by 0.2mg/kg uranyl acetate (UA) (subtoxic dose) were rechallenged with 4mg/kg UA (nephrotoxic dose) to establish the acquired resistance model. Cell cycle was inhibited by colchicine to examine the contribution of accelerated PT cell proliferation evaluated by in vivo bromodeoxyuridine (BrdU) labeling on acquired resistance to subsequent nephrotoxic insult. Hepatocyte growth factor (HGF)/c-Met axis and other related factors of cell cycle were analyzed. The acquired resistance to rechallenge injury with nephrotoxic dose of UA in rats recovered from mild renal injury was associated with an earlier increase in BrdU-positive PT cells, accelerated upregulation of HGF mRNA, c-Met mRNA/protein, cyclin D1, phospho-Rb and an earlier phenotypic change of PT cells. Colchicine inhibited PT cell proliferation, reduced the upregulated cyclin D1 and phospho-Rb in the kidney, completely abolishing acquired resistance. Cell cycle progression with upregulated renal HGF/c-Met axis may contribute to the accelerated recovery from acute renal failure in rats that recovered from prior mild renal damage, followed by nephrotoxic insult, resulting in partial acquired resistance.

Vascular Calcification Is Associated with Cortical Bone Loss in Chronic Renal Failure Rats with and without Ovariectomy: The Calcification Paradox

Background: Increased bone loss has been associated with the development of vascular calcification in patients with chronic renal failure (CRF). In this study, the effect of impaired bone metabolism on aortic calcifications was investigated in uremic rats with or without ovariectomy. Methods: CRF was induced by administration of a 0.75% adenine/2.5% protein diet for 4 weeks. In one group, osteoporosis was induced by ovariectomy (CRF-OVX), while the other group underwent a sham-operation instead (CRF). A third group consisted of ovariectomized rats with normal renal function (OVX). At regular time intervals throughout the study, bone status and aortic calcifications were evaluated by in vivo micro-CT. At sacrifice after 6 weeks of CRF, bone histomorphometry was performed and vascular calcification was assessed by bulk calcium analysis and Von Kossa staining. Results: Renal function was significantly impaired in the CRF-OVX and CRF groups. Trabecular bone loss was seen in all groups. In the CRF-OVX and CRF groups, trabecular bone density was restored after adenine withdrawal, which coincided with cortical bone loss and the development of medial calcifications in the aorta. No significant differences with regard to the degree of aortic calcifications were seen between the two CRF groups. Neither cortical bone loss nor calcifications were seen in the OVX group. Cortical bone loss significantly correlated with the severity of vascular calcification in the CRF-OVX and CRF groups, but no associations with trabecular bone changes were found. Conclusions: Cortical rather than trabecular bone loss is associated with the process of calcification in rats with adenine- induced CRF.

A study on the protective effect of bone marrow derived mesenchymal stem cells on chronic renal failure in rats

Chronic renal failure (CRF) is a common disease with high morbidity and mortality. The inadequacy of current treatment modalities and insufficiency of donor organs for cadaveric transplantation have driven a search for improved methods of dealing with renal failure. This raises the concept of cell-based therapy using mesenchymal stem cells (MSCs). The purpose of this work is to evaluate the effect of MSCs in rats with CRF and to detect the level of B-cell lymphoma 2 (Bcl-2) and basic fibroblast growth factor (bFGF) as possible antiapoptotic and anti-inflammatory paracrine mediators of MSCs action. This study was carried on female albino rats, which were divided into 3 groups, control group, CRF group and CRF/MSCs group. MSCs were derived from bone marrow of male albino rats and were characterized morphologically and by RT-PCR for CD29. Serum urea, creatinine, Na, K, systolic blood pressure and 24-hour urinary albumin were estimated for all groups, Y-chromosome gene (Sry) was detected by PCR in renal tissue. Also Bcl-2 and bFGF were examined by RT-PCR in renal tissue of all studied groups and the kidney was examined pathologically. The results of this work showed that CRF rats receiving MSCs showed significantly lowered serum urea, creatinine and urinary albumin levels compared to the CRF group. Also improvement of serum Na and K was observed in CRF/MSCs group compared to CRF group. As regard Bcl-2 and bFGF they were highly expressed in renal tissue of CRF/MSCs group compared to the CRF group. The (Sry) gene was detected by PCR in the renal tissue of CRF/MSCs group. These results demonstrate a potential of MSCs to ameliorate the kidney function in rats with CRF possibly through the antiapoptotic and anti-inflammatory paracrine mediators of MSCs.

NF-κB plays an important role in indoxyl sulfate-induced cellular senescence, fibrotic gene expression, and inhibition of proliferation in proximal tubular cells

We previously demonstrated that indoxyl sulfate induces senescence and dysfunction of proximal tubular cells by activating p53 expression. However, little is known about the role of nuclear factor (NF)-κB in these processes. The present study examines whether activation (phosphorylation) of NF-κB by indoxyl sulfate promotes senescence and dysfunction in human proximal tubular cells (HK-2 cells). Indoxyl sulfate induced phosphorylation of NF-κB p65 on Ser-276, which was suppressed by N-acetylcysteine, an antioxidant. Furthermore, indoxyl sulfate induced NF-κB p65 expression. Inhibitors of NF-κB (pyrrolidine dithiocarbamate and isohelenin) and NF-κB p65 small interfering RNA (siRNA) suppressed indoxyl sulfate-induced senescence-associated β-galactosidase activity and expression of p53, transforming growth factor (TGF)-β1, and α-smoothe muscle actin (SMA). The induction of p53 expression and p53 promoter activity by indoxyl sulfate were inhibited by pifithrin-α, p-nitro, an inhibitor of p53, whereas p53-transfected cells showed enhanced p53 promoter activity. NF-κB inhibitors suppressed indoxyl sulfate-induced p21 expression, whereas NF-κB p65 siRNA enhanced its expression. NF-κB inhibitors partially alleviated indoxyl sulfate-induced inhibition of cellular proliferation. NF-κB p65 siRNA-transfected cells showed less proliferation in the presence of indoxyl sulfate than control cells. Phosphorylated NF-κB p65 was expressed and colocalized with p53, p21, β-galactosidase, TGF-β1, and α-SMA in the kidneys of chronic renal failure (CRF) rats. AST-120, which reduces serum indoxyl sulfate level, suppressed their expression in the CRF rat kidneys. Taken together, NF-κB plays an important role in indoxyl sulfate-induced cellular senescence, fibrotic gene expression, and inhibition of proliferation in proximal tubular cells. More notably, indoxyl sulfate accelerates proximal tubular cell senescence with progression of CRF through reactive oxygen species-NF-κB-p53 pathway.