Cisplatin-induced lipid peroxidation and decrease of gluconeogenesis in rat kidney cortex: different effects of antioxidants and radical scavengers

Xanthorrhizol has a potential to attenuate the high dose cisplatin-induced nephrotoxicity in mice

Cisplatin is a widely used anticancer drug, but it can produce undesirable side effects such as nephrotoxicity. The present study investigated the effect of xanthorrhizol isolated from Curcuma xanthorrhiza Roxb. (Zingiberaceae) on cisplatin-induced nephrotoxicity in mice. A single dose of cisplatin (45 mg/kg, i.p.) significantly elevated the levels of blood urea nitrogen, serum creatinine, and the kidney to body weight ratio, but the pretreatment of xanthorrhizol (200 mg/kg/day, per os) for 4 days significantly attenuated the cisplatin-induced nephrotoxicity. The preventive effect of xanthorrhizol was more efficacious than that of curcumin with the same amount (200 mg/kg). However, this effect seemed not to be related with the ability of xanthorrhizol to regulate the DNA-binding activities of transcription factors such as nuclear factor-kappaB (NF-kappaB) and activator protein 1 (AP-1). This is first time the preventive effect of xanthorrhizol on cisplatin-induced nephrotoxicity has been demonstrated, and these data suggest that the administration of xanthorrhizol is a promising approach in the treatment of nephrotoxicity caused by cisplatin.

Effect of oral administration of Arabic gum on cisplatin-induced nephrotoxicity in rats

It has been recently postulated from our laboratory that Arabic gum (AG) offers a protective effect in the kidney of rats against nephrotoxicity induced by gentamicin via inhibiting lipid peroxidation. It has also recently shown a powerful antioxidant effect through scavenging superoxide anions. In this study we utilized a rat model of cisplatin (CP)-induced nephrotoxicity to determine its peak time following (1, 2, 5, and 7 days) of a single CP (7.5 mg/kg, i.p.) injection. Also, a possible protective effect of cotreatment with AG (7.5 g/kg/day p.o.) on CP-induced nephrotoxicity was investigated. Biochemical as well as histological assessments were carried out. CP-induced nephrotoxicity was manifested by significant elevations of the functional parameters blood urea, serum creatinine, and kidney/body weight ratio. Maximum toxic effects of CP were observed 5 days after its injection, while it started after day 1 in the biochemical parameters, such as glutathione depletion in the kidney tissue with concomitant increases in lipid peroxides and platinum content. Additionally, severe necrosis and desquamation of tubular epithelial cells in renal cortex as well as interstitial nephritis were observed after 5 days in CP-treated animals. Five days after AG cotreatment with CP did not protect the kidney from the damaging effects of CP. However, it significantly reduced CP-induced lipid peroxidation. These findings suggest that lipid peroxidation is not the main cause of CP-induced nephrotoxicity but it is rather more dependent on other factors such as platinum disposition in renal interstitial tubules.

Antioxidantes da dieta como inibidores da nefrotoxicidade induzida pelo antitumoral cisplatina

A cisplatina é uma droga antineoplásica altamente efetiva contra vários tipos de cânceres humanos, tais como tumores do testículo e ovário, câncer da cabeça e pescoço e câncer do pulmão. Entretanto, a nefrotoxicidade é um dos principais efeitos colaterais da terapia com a cisplatina. A gravidade da nefrotoxicidade induzida pela cisplatina está relacionada com a concentração de platina nos rins. As evidências mostram que a nefrotoxicidade induzida pela cisplatina é atribuída ao dano oxidativo resultante da geração de radicais livres, e que a administração de antioxidantes é eficiente na inibição destes efeitos colaterais. Uma abordagem alternativa para proteger os roedores dos efeitos colaterais da cisplatina é o uso de conhecidos antioxidantes da dieta. Alguns estudos têm sido realizados para diminuir a peroxidação lipídica e os efeitos citotóxicos induzidos pela cisplatina, com o emprego de antioxidantes da dieta, tais como, selenito de sódio, vitaminas C e E, curcumina e o carotenóide bixina. Nós sugerimos que aqueles antioxidantes da dieta têm efeito nefroprotetor, e que os mecanismos antioxidantes destes compostos deveriam ser explorados durante a quimioterapia com a cisplatina.

The Effect of Eriobotrya japonica Seed Extract on Oxidative Stress in Adriamycin-Induced Nephropathy in Rats

Eriobotrya japonica has been used as a medicinal plant for a long time, and its leaves are known to have many physiological actions such as anti-inflammatory, antitussive, and expectoran. In contrast, Eriobotrya japonica seeds are only known to contain amygdalin, and almost no investigations of its pharmacological action have been performed. Moreover, some anticancer agents such as adriamycin cause renal disorders as an adverse effect, and the mechanism of the adverse effect is considered to involve oxidative stress. We have reported that Eriobotrya japonica seed extract has an inhibitory effect on liver disorders. In this study, we prepared a 70% ethanol extract of Eriobotrya japonica seeds and administered the extract to rats with renal disorder induced by a single administration of 7 mg/kg body weight adriamycin, and investigated the usefulness of the extract. Increases in indices of renal function, plasma urea nitrogen, were significantly inhibited in rats treated with the Eriobotrya japonica extract compared to rats treated with tap water. In addition, the renal tissue level of reduced glutathione was significantly high in rats that ingested the extract, while the lipid peroxide levels in plasma and renal tissue were significantly low. However, no effect on renal tissue antioxidative enzymes was observed, suggesting that Eriobotrya japonica seed extract has direct antioxidative action. Based on these findings, Eriobotrya japonica seed extract may be effective in reducing the oxidative stress of adriamycin-induced renal disorder. Therefore, ingestion of Eriobotrya japonica seed extract may contribute to a reduction of the adverse effects of adriamycin.

The Protective Effects of Acetylsalicylic Acid on Free Radical Production in Cisplatin Induced Nephrotoxicity: An Experimental Rat Model

Cisplatin-induced nephrotoxicity is closely associated with an increase in lipid peroxidation. In several previous reports it was claimed that acetylsalicylic acid (ASA) shows its therapeutic potential as a free radical scavenger. The aim of the study was to investigate effects of ASA on cisplatin induced nephrotoxicity in an experimental rat model. Control animals (n:7) were administered 1 mL saline solution intraperitoneal (i.p.). Cisplatin group (n:7) was treated with a single dose of cisplatin i.p. (6 mg/kg), ASA group (n:7) was treated with i.p. (2.5 mg/kg) per day during the study, cisplatin plus ASA group (n:7) was administered single dose cisplatin i.p. (6 mg/kg) plus ASA (2.5 mg/kg) during 5 days. At the end of the study, Catalase (CAT), Glutathione Peroxidase (GSH-Px), Superoxide Dismutase (SOD), Nitric Oxide Synthase (NOS) enzymes activities and Malondialdehyde (MDA), Antioxidant Potential (AOP) levels were measured in both erythrocytes and renal tissues. Urea and creatinine levels and renal tissue necrosis in cisplatin plus ASA group were significantly lower than cisplatin group (p = 0.000, p = 0.014, p = 0.015). SODr activities and MDAr levels of cisplatin plus ASA group were also significantly lower than cisplatin group (p = 0.000, p = 0.029). These results show that cisplatin and ASA combination decreases the levels of urea and creatinine, reduces necrosis and improves antioxidant enzyme activities, MDA and AOP in rat kidney.

Protection against cisplatin-induced nephrotoxicity by Cu(II)2(3,5-diisopropylsalicylate)4

The ability of Cu(II)(2)(3,5-diisopropylsalicylate)(4), CuDIPS, which exhibits superoxide dismutase (SOD)-like activity, to prevent cisplatin-induced nephrotoxicity was examined in rats. Rats were divided into four groups and treated as follows: (i) vehicle control; (ii) cisplatin (16 mg/kg, intraperitoneally); (iii) CuDIPS (10 mg/kg, intraperitoneally); and (iv) cisplatin plus CuDIPS. Rats were sacrificed 3 days post-treatment. Cisplatin alone resulted in significantly increased plasma creatinine and urea. Administration of 10 mg/kg CuDIPS prevented the cisplatin-induced elevation of plasma creatinine and urea and protected against kidney damage. Relative to controls, rats that received cisplatin treatment displayed a decrease of reduced glutathione (GSH) and elevated platinum and thiobarbituric acid reactive substances (TBARS) levels in the kidney. In comparison with controls, activities of antioxidant enzymes (SOD, CAT, GSH-Px and GSH-Rd) were also reduced in the kidney of rats treated with cisplatin. Administration of 10 mg/kg CuDIPS prevented cisplatin-induced alterations in renal platinum, GSH, TBARS, and antioxidant enzyme activities. This study suggests that the protection offered by CuDIPS against cisplatin-induced nephrotoxicity is partly related to maintenance of renal antioxidant systems.

Differential roles of hydrogen peroxide and hydroxyl radical in cisplatin-induced cell death in renal proximal tubular epithelial cells

Reactive oxygen species (ROS) have been suggested as important mediators of cisplatin-induced acute renal failure in vivo. However, our previous studies have shown that cisplatin-induced cell death in vitro could not be prevented by scavengers of hydrogen peroxide and hydroxyl radical in rabbit renal cortical slices. This discrepancy may be attributed to differential roles of ROS in necrotic and apoptotic cell death. We therefore examined, in this study, the roles of ROS in necrosis and apoptosis induced by cisplatin in primary cultured rabbit proximal tubule. Cisplatin induced necrosis at high concentrations over a few hours and apoptosis at much lower concentrations over longer periods. Necrosis induced by high concentration of cisplatin was prevented by a cell-permeable superoxide scavenger (tiron), hydrogen peroxide scavengers (catalase and pyruvate), and antioxidants (Trolox and deferoxamine), whereas hydroxyl radical scavengers (dimethythiourea and thiourea) did not affect the cisplatin-induced necrosis. However, apoptosis induced by lower concentration of cisplatin was partially prevented by tiron and hydroxyl radical scavengers but not by hydrogen peroxide scavengers and antioxidants. Cisplatin-induced apoptosis was mediated by the signaling pathway that is associated with cytochrome c release from mitochondria and caspase-3 activation. These effects were prevented by tiron and dimethylthiourea but not by catalase. Dimethylthiourea produced a significant protection against cisplatin-induced acute renal failure, and the effect was associated with an inhibition of apoptosis. These results suggest that hydrogen peroxide is involved in the cisplatin-induced necrosis, whereas hydroxyl radical is responsible for the cisplatin-induced apoptosis. The protective effects of hydroxyl radical scavengers are associated with an inhibition of cytochrome c release and caspase activation.

L-arginine ameliorates kidney function and urinary bladder sensitivity in experimentally-induced renal dysfunction in rats

Effects of L-arginine and NG-nitro-L-arginine methyl ester (L-NAME) on the renal dysfunction that is induced by cisplatin (CDDP) were investigated. A single dose of CDDP (7.5 mg/kg i.p.) induced renotoxicity, which was manifested by increasing the sensitivity of isolated urinary bladder rings to acetylcholine (ACh), together with a significant elevation of serum urea and creatinine, and a severe decrease in serum albumin. Moreover, renal dysfunction was further confirmed by a significant decrease of enzyme activities, such as glutathione peroxidase, GSH-Px (E.C 1.11.1.9), catalase (E.C 1.11.1.6), as well as a significant increase in lipid peroxides that were measured as malondialdhyde (MDA) in kidney tissue homogenates. The administration of L-arginine (70 mg/kg/d p.o in drinking water 5 d before and 5 d after the CDDP injection) significantly ameliorated the renotoxic effects of CDDP, as judged by restoring the normal responses of isolated bladder rings to Ach, and also by an improvement in a range of renal function indices, which included serum urea and creatinine concentrations and kidney weight. In addition, L-arginine prevents the rise of MDA, as well as a reduction of GSH-Px and catalase activities in kidney tissues homogenates. On the other hand, the administration of L-NAME (4 mg/kg/d p.o) resulted in no protection against renal dysfunction that was induced by CDDP treatment. The findings of this study suggest that L-arginine can attenuate kidney injury that is produced by CDDP treatment. In addition, L-arginine may be a beneficial remedy for CDDP-induced renal toxicity, and could be used to improve the therapeutic index of CDDP.

Arrest of apoptosis in auditory neurons: implications for sensorineural preservation in cochlear implantation

HYPOTHESIS

The JNK/c-Jun cell death pathway is a major pathway responsible for the loss of oxidative stress-damaged auditory neurons.

BACKGROUND

Implantation of patients with residual hearing accentuates the need to preserve functioning sensorineural elements. Although some auditory function may survive electrode insertion, the probability of initiating an ongoing loss of auditory neurons and hair cells is unknown. Cochlear implantation can potentially generate oxidative stress, which can initiate the cell death of both auditory neurons and hair cells.

METHODS

Dissociated cell cultures of P4 rat auditory neurons identified the apoptotic pathway initiated by oxidative stress insults (e.g., loss of trophic factor support) and characterized this pathway by arresting translation of pathway-specific mRNA with antisense oligonucleotide treatment and with the use of pathway specific inhibitors. The presence or absence of apoptosis-specific protein and changes in the level of neuronal survival measured the efficacy of these interventional strategies.

RESULTS

These in vitro studies identified the JNK/c-Jun cascade as a major initiator of apoptosis of auditory neurons in response to oxidative stress. Neurons pretreated with c-jun antisense oligonucleotide and exposed to high levels of oxidative stress were rescued from apoptosis, whereas neurons in treatment control cultures died. Treatment of oxidative-stressed cultures with either curcumin, a MAPKKK pathway inhibitor, or PD-098059, a MEK1 inhibitor, blocked loss of neurons via the JNK/c-Jun apoptotic pathway.

CONCLUSION

Blocking the JNK/c-Jun cell death pathway is a feasible approach to treating oxidative stress-induced apoptosis within the cochlea and may have application as an otoprotective strategy during cochlear implantation.

Pharmacologic Manipulation of the Labyrinth with Novel and Traditional Agents Delivered to the Inner Ear

We describe the methodology and rationale behind the delivery of therapeutic medicines to the inner ear. The inner ear has long been impervious to pharmacologic manipulation. This is most likely the result of a protective mechanism called the blood-labyrinth barrier, whose function closely resembles that of the blood-brain barrier. This protective barrier impedes the clinician's ability to treat inner ear diseases with systemically administered medications. Since 1935, otolaryngologists have attempted to manipulate the inner ear with transtympanically injected medicines. Success has varied widely, but medicinal ablation of vestibular function can be achieved in this manner. Unfortunately, the auditory system is also at great risk from any medicine that is delivered to the inner ear via the middle ear. Over the past 10 years, significant improvements in drug delivery have allowed for more “titratable” treatment, which has reduced (but not eliminated) the risk of permanent hearing loss. In this article, we discuss both novel and time-tested methods of delivering medicines to the inner ear. We also review the classes of medications that alter inner ear function and the attendant risks of such treatments.

Possible involvement of oxidative stress in cisplatin-induced apoptosis in LLC-PK1 cells

Use of cisplatin, a chemotherapeutic agent, is associated with toxicity as a significant number of patients develop a decline in renal function. The mechanisms by which cisplatin produces renal injury are not well understood. It has been suggested that free radical-catalyzed lipid peroxidation can induce apoptosis or necrosis leading to renal injury. This study examined whether low concentrations of cisplatin induce apoptosis in LLC-PK1 cells and whether caspases 1, 2, 3, 8, and 9 are activated during this event. Our results show a dose- and time-dependent induction of apoptosis by micromolar concentrations of cisplatin. Expression of oncogenes c-myc and p53 was induced, and except for caspase 1, all the other caspases tested were activated. Z-VAD, the broad-spectrum inhibitor of caspases, prevented caspase activation and apoptosis, but not c-myc and p53 induction. On the other hand, N-acetylcysteine prevented cisplatin-induced apoptosis as well as c-myc induction but not p53 induction. The antioxidant trolox also prevented cisplatin-induced apoptosis. The results suggest that antioxidants and caspase inhibitors may alleviate cisplatin-associated nephrotoxicity.

Melatonin prevents the increase in hydroxyl radical-spin trap adduct formation caused by the addition of cisplatin in vitro

We studied the generation of reactive oxygen species (ROS) caused by cisplatin administration and the preventive effect of melatonin, the main secretory product of the pineal gland, on the reaction in vitro using electron spin resonance spectroscopy. Cisplatin induced generation of the hydroxyl radical (OH*) in phosphate buffer in pH 7.4 as a dose-dependent manner. However, OH* was not generated in phosphate buffer containing chloride ions at concentration exceeding 120 mM. The induction of OH. production by cisplatin was completely inhibited by the addition of melatonin, but not by the addition of 6-hydroxymelatonin, which is a hepatic metabolite of melatonin. Furthermore, melatonin was the most effective agent for preventing of OH* formation among various well-known antioxidants including mannitol and reduced glutathione. These results indicate that melatonin may scavenge OH. directly and thereby prevent renal tissue damage caused by OH* produced in response to cisplatin treatment.

Effect of 6-hydroxydopamine on gluconeogenesis in the rat renal cortex

1. In the present study, the effects of 6-hydroxydopamine (6-OHDA) on renal gluconeogenesis were investigated in vitro using rat renal cortical slices. Cisplatin, a known nephrotoxin, was used as a positive control. The working hypothesis for the present study was that 6-OHDA, as a reactive oxygen species-producing agent, could inhibit renal gluconeogenesis. 2. 6-Hydroxydopamine is used for chemical sympathectomy because it selectively destroys adrenergic nerve endings. Long-term use of levodopa causes a variety of side-effects in parkinsonian patients. 6-Hydroxydopamine has been reported to be present in the urine of parkinsonian patients on levodopa medication. The renal toxicity of endogenously formed 6-OHDA is a matter of concern in these patients. 3. In one series of experiments, renal cortical slices were incubated for 60 min in medium containing 0.5, 1.0, 2.08, 5.15, 10.30 or 20.60 mg/mL 6-OHDA at 37 degrees C under a 100% O2 atmosphere. In another series of experiments, renal cortical slices were incubated in medium containing 10.30 mg/mL 6-OHDA for 15, 30, 45, 60, 90 or 120 min or in 6-OHDA-free medium. 4. In a second series of experiments, renal cortical slices were incubated for 60 min in medium containing 0.25, 0.50, 0.75, 1.0, 1.25 or 1.50 mg/mL cisplatin at 37 degrees C under a 100% O2 atmosphere. In another set of experiments, renal cortical slices were incubated in medium containing 1 mg/mL cisplatin for 15, 30, 45, 60, 90 or 120 min or in a cisplatin-free medium. 5. The results of the studies in which slices were incubated in 6-OHDA-containing media indicate that 6-OHDA induced a time- and concentration-dependent decrease in renal gluconeogenesis. Therefore, 6-OHDA causes functional injury of renal proximal tubule cells responsible for renal gluconeogenesis, thus leading to nephrotoxicity.

Protective effect of procaine hydrochloride on cisplatin-induced alterations in rat kidney

Efforts have been made to reduce the undesirable side effects of cisplatin, mainly nephro- and neurotoxicity, but their reduction is usually accompanied by a concomitant inhibition of antitumor activity. The local anesthetic procaine hydrochloride (P.HCl) improves the therapeutic index of cisplatin not only by the reduction of its nephro- and hemotoxicity, but also by an increase of its antitumor activity. We therefore investigated the effects of a combined treatment of cisplatin and P.HCl on rat kidneys and compared this to kidneys from rats treated with a toxic dose of cisplatin or P.HCl alone. Treatment with a saline solution was used as control. Dehydrogenase activities [succinate dehydrogenase (SDH) and NADPH diaphorase reaction demonstrating nitric oxide synthase (NOS/NADPHd)] and phosphatase activities [K -nitrophenyl phosphatase (K pNPPase), alkaline phosphatase (AlPase) and acid phosphatase (AcPase)] were studied on cryostatic sections of kidneys from controls and treated rats. Evidence of heavy morphological damage and altered AlPase and AcPase activities induced by cisplatin were observed in the S3 segment of the proximal tubules. In addition, SDH and K pNPPase activities showed some changes in the distal tubule cells. The NOS/NADPHd activity in macula densa was drastically reduced. Combined treatment of cisplatin and P.HCl greatly attenuated morphological alterations of the rat kidney and reduced the changes in enzyme activities, except for NOS/NADPHd activity, compared to the cisplatin-treated group of animals. The study indicates that, in cisplatin-induced nephrotoxicity, a significant role is played by enzyme activities, in particular K pNPPase and NOS/NADPHd, and that P.HCl can mitigate the nephrotoxicity of cisplatin, possibly by influencing some enzyme activities involved in important renal metabolic pathways.

Physiological and pharmacological concentrations of melatonin protect against cisplatin-induced acute renal injury

Cisplatin [cis-diaminedichloroplatinum(II), CDDP] is a widely used antineoplastic drug. However, it has major side-effects such as acute tubular necrosis (ATN). There are a number of studies concerning the role of reactive oxygen radical species in the pathophysiology of CDDP-dependent ATN. Several antioxidant agents have been reported to prevent this side-effect but there is no study regarding the protective action of either physiological or pharmacological concentrations of melatonin. Melatonin, the chief secretory product of the pineal gland, is a direct free radical scavenger and indirect antioxidant. We investigated the effects of melatonin on CDDP-induced changes of renal malondialdehyde (MDA), a lipid peroxidation product, and blood urea nitrogen (BUN) and serum creatine (Cr). The morphological changes in kidney were also examined using light microscopy. The rats were divided into two groups: pinealectomized (Px) and sham-operated (non-Px). Both CDDP and melatonin were administered to all groups. MDA levels were found to be higher in Px than non-Px animals. CDDP administration to Px or non-Px rats increased renal MDA levels and melatonin administration either before or after CDDP injection caused significant decreases in MDA in kidney compared with those in rats treated with CDDP alone. Serum levels of BUN and Cr did not change as a result of any treatment. Morphological tubule damage because of CDDP was more severe in the renal cortex than in the medulla. The damage to the kidney induced by CDDP was reversed by melatonin. The results show that pharmacological and physiological concentrations of melatonin reduce CDDP-induced renal injury.

Protection by a radical scavenger edaravone against cisplatin-induced nephrotoxicity in rats

Acute renal failure is a dose-limiting factor of cisplatin chemotherapy. Here, we show the protective effect of edaravone, a recently developed radical scavenger for clinical use, against cisplatin-induced renal dysfunction in rats. A marked increase in blood urea nitrogen and creatinine in serum, and histological changes including vacuolation, necrosis and protein casts were observed in proximal renal tubules at the fourth day after cisplatin injection (5-10 mg/kg). Repeated injection of edaravone (1-10 mg/kg, i.v. twice a day for 3 days) reversed the cisplatin-induced elevation of blood urea nitrogen and creatinine, and morphological changes in a dose-dependent manner. In particular, the protective effect of edaravone was almost complete at 10 mg/kg. Moreover, the compound was still fully effective, when it was administered only at the second day after cisplatin injection. On the other hand, the glutathione content in renal tissues lowered at the fourth day after cisplatin injection, which was reversed by the late treatment with edaravone. These findings suggest that the clinically available radical scavenger edaravone is potentially useful for the prevention of cisplatin-induced renal toxicity.

N-acetylcysteine as salvage therapy in cisplatin nephrotoxicity

N-acetylcysteine (NAC) repletes intracellular stores of reduced glutathione and may be a scavenger of oxygen free radicals. We report a 52-year-old female who developed acute renal insufficiency after administration of one dose of 150 mg of cisplatin for treatment of squamous cell cancer of the esophagus. Her blood urea nitrogen and creatinine rose from 12 and 0.7 mg/dL, respectively, to 24 and 1.8 mg/dL on day 5 after cisplatin. On that day the patient was begun on NAC, starting with a loading dose of 140-mg/kg-body weight followed by 70mg/kg every 4h for 4 days. Two days after starting NAC her renal function began to improve, and although she failed to complete a full course of the drug, by day 10 her serum creatinine had fallen to 0.8 mg/dL. A previous report showed that N-acetylcysteine might reverse cisplatin-induced renal toxicity. Our case supports this hypothesis.

Specificity of resistance to oxidative stress

Two clonal nerve-like cell lines derived from HT22 and PC12 have been selected for resistance to glutamate toxicity and amyloid toxicity, respectively. In the following experiments it was asked if these cell lines show cross-resistance toward amyloid beta peptide (Abeta) and glutamate as well as toward a variety of additional neurotoxins. Conversely, it was determined if inhibitors of oxytosis, a well-defined oxidative stress pathway, also protect cells from the neurotoxins. It is shown that both glutamate and amyloid resistant cells are cross resistant to most of the other toxins or toxic conditions, while inhibitors of oxytosis protect from glutathione and cystine depletion and H2O2 toxicity, but not from the toxic effects of nitric oxide, rotenone, arsenite or cisplatin. It is concluded that while there is a great deal of cross-resistance to neurotoxins, the components of the cell death pathway which has been defined for oxytosis are not used by many of the neurotoxins.

Protective effect of aminoguanidine against nephrotoxicity induced by cisplatin in normal rats

The effect of aminoguanidine (AG) on nephrotoxicity induced by cisplatin (CDDP) was investigated. A single dose of CDDP (7.5 mg/kg i.p.) induced nephrotoxicity, manifested biochemically by a significant elevation in serum urea, creatinine and a severe decrease in serum albumin. Moreover, marked increases in kidney weight, urine volume and urinary excretion of albumin were observed. Nephrotoxicity was further confirmed by a significant decrease in glutathione-S-transferase (GST, E.C. 2.5.1.18), glutathione peroxidase (GSH-Px, E.C. 1.11.1.9) and catalase (E.C. 1.11.1.6) and a significant increase in lipid peroxides measured as malondialdhyde (MDA) in kidney homogenates. Administration of AG (100 mg/kg per day p.o.) in drinking water 5 days before and 5 days after CDDP injection produced a significant protection against nephrotoxicity induced by CDDP. The amelioration of nephrotoxicity was evidenced by significant reductions in serum urea and creatinine concentrations. In addition, AG tended to normalize decreased levels of serum albumin. Urine volume, urinary excretions of albumin and GST and kidney weight were significantly decreased. Moreover, AG prevented the rise of MDA and the reduction of GST and GSH-Px activities in the kidney. These results suggest that AG has a protective effect on nephrotoxicity induced by CDDP and it may therefore improve the therapeutic index of CDDP.

Carboplatin induces less apoptosis in the cochlea of guinea pigs than cisplatin

BACKGROUND

Cisplatin (CDDP) is known to cause inner ear damage while carboplatin (CBDCA) induces less ototoxicity than CDDP. We examined apoptotic changes in the cochlea of guinea pigs after injection of CDDP or CBDCA using immunohistochemical and electrophysiological techniques.

METHODS

Three days after the injection of each solution, the cochleas were immunohistochemically examined for the presence of fragments of single-stranded DNA (ssDNA). The auditory brain stem response was recorded before and three days after the injection.

RESULTS

We detected fragments of ssDNA in the stria vascularis and the spiral ligament of the CDDP-treated cochlea. In this group, the threshold of the auditory brainstem response was significantly elevated, however, in the CBDCA group, no apparent change of the threshold was detected. In the CBDCA group, fragments of ssDNA were detected in the stria vascularis and the spiral ligament. The number of cells that stained positive for ssDNA, was less than that in the CDDP group.

CONCLUSIONS

Our findings indicate that CBDCA induces less apoptosis than CDDP and that this phenomenon contributes to the ototoxicity of CDDP.

Salicylate protects hearing and kidney function from cisplatin toxicity without compromising its oncolytic action

Salicylate has recently been demonstrated to protect against the auditory and vestibular side effects of aminoglycoside antibiotics. Similarities in the toxic mechanisms suggest salicylate as a treatment strategy to prevent the ototoxic side effects of cisplatin (CDDP). We first tested protection of the inner ear in Wistar rats receiving a single infusion of 16 mg CDDP/kg body weight with or without treatment with 100 mg/kg salicylate (bid) for 5 days beginning one day before the CDDP infusion. Cisplatin induced a threshold shift of more than 30 dB (at 14 kHz; measured by auditory evoked brain stem response) that was significantly reduced by salicylate. We then examined the protective potential of salicylate on the cochlea, peripheral nerves, and kidney in a rat model of breast cancer--Fisher344 rats implanted with highly metastatic MTLn3 breast cancer cells. Animals received 3 x 5 mg CDDP/kg (given every third day), and salicylate was administered at 100 mg/kg (bid) from 2 days before to 3 days after CDDP treatment. Salicylate significantly attenuated the CDDP-induced threshold shift from approximately 20 dB (at 16 and 24 kHz) to approximately 5 dB, and drastically reduced the loss of cochlear outer hair cells. Likewise, salicylate protected kidney function (measured as plasma blood urea nitrogen and creatinine levels) from CDDP toxicity. Protection of nerve conduction velocities of both sensory and motor nerves was minimal. The chemotherapeutic efficacy of CDDP on suppression of tumor mass and cancer cell metastasis remained unaffected by salicylate. The results suggest that administration of salicylate may become the basis of an effective therapeutic intervention against the ototoxic and nephrotoxic side effects associated with CDDP chemotherapy.

BGP-15 - a novel poly(ADP-ribose) polymerase inhibitor - protects against nephrotoxicity of cisplatin without compromising its antitumor activity

Nephrotoxicity is one of the major dose limiting side effects of cisplatin chemotherapy. The antitumor and toxic effects are mediated in part by different mechanisms, thus, permitting a selective inhibition of certain side effects. The influence of O-(3-piperidino-2-hydroxy-1-propyl)nicotinic amidoxime (BGP-15) - a poly(ADP-ribose) polymerase (PARP) inhibitor - on the nephrotoxicity and antitumor efficacy of cisplatin has been evaluated in experimental models. BGP-15 either blocked or significantly reduced (60-90% in 100-200 mg/kg oral dose) cisplatin induced increase in serum urea and creatinine level in mice and rats and prevented the structural degeneration of the kidney, as well. The nephroprotective effect of BGP-15 treatment was revealed also in living mice by MRI analysis manifesting in the lack of oedema which otherwise developed as a result of cisplatin treatment. The protective effect was accompanied by inhibition of cisplatin-induced poly-ADP-ribosylation and by the restoration of the disturbed energy metabolism. The preservation of ATP level in the kidney was demonstrated in vivo by localized NMR spectroscopy. BGP-15 decreased cisplatin-induced ROS production in rat kidney mitochondria and improved the antioxidant status of the kidney in mice with cisplatin-induced nephropathy. In rat kidney, cisplatin caused a decrease in the level of Bcl-x, a mitochondrial protective protein, and this was normalized by BGP-15 treatment. On the other hand, BGP-15 did not inhibit the antitumor efficacy of cisplatin in cell culture and in transplantable solid tumors of mice. Treatment with BGP-15 increased the mean survival time of cisplatin-treated P-388 leukemia bearing mice from 13 to 19 days. PARP inhibitors have been demonstrated to diminish the consequences of free radical-induced damage, and this is related to the chemoprotective effect of BGP-15, a novel PARP inhibitor. Based on these results, we propose that BGP-15 represents a novel, non-thiol chemoprotective agent.

Cisplatin induces acute renal failure by impairing antioxidant system in guinea pigs: effects of antioxidant supplementation on the cisplatin nephrotoxicity

This study aims to investigate the role of oxidants in cisplatin-induced nephrotoxicity. Cisplatin was administered intraperitoneally (i.p.) in a single dose (5 mg/kg) and guinea pigs were killed either after 24 h or 7 days. The same experiment was performed using animals treated with vitamins C and E combination and a natural antioxidant extract (SARMEX). The kidneys were then removed to be used in the analyses. Blood samples were also obtained from the animals to be used in routine biochemical assays. Twenty-four hours after treatment there was a significant decrease in the renal activities of total superoxide scavenger activity (TSSA), superoxide dismutase (SOD) and catalase (CAT) accompanied by a rise in malondialdehyde (MDA) levels. After 7 days, the fall in kidney enzymatic activities was far greater, while the increase in blood urea (BUN) and creatinine (CRE) was marked. Treatment with antioxidants causes significant increases in renal TSSA (7 day), non-enzymatic superoxide scavenger activity (NSSA) (24 h and 7 day) and SOD (7 day) activities, does not change glutathione peroxidase (GSH-Px) activity and decreases renal MDA (24 h and 7 day), blood BUN (7 day) and CRE (7 day) levels. Our results suggest that cisplatin treatment impairs both enzymatic and non-enzymatic antioxidant systems and causes peroxidation in the renal tissue, which leads to kidney failure. Antioxidant supplementation strengthens the renal antioxidant system, eliminates oxidation reactions, and prevents cisplatin-induced kidney failure.

Role of ginsenoside-Rd in cisplatin-induced renal injury: special reference to DNA fragmentation

DNA of LLC-PK(1) cells cultured with cisplatin was fragmented to produce low-molecular-weight structures. Agarose gel electrophoresis of the DNA revealed a ladder pattern characteristic of apoptosis, indicating the induction of apoptosis by cisplatin. However, the degree of apoptosis was lower in cells cultured with cisplatin in the presence of ginsenoside-Rd, and this was accompanied by suppressed leakage of lactic dehydrogenase into the culture medium. The ladder pattern was detected on electrophoresis of DNA in renal tissue samples obtained from rats given an intravenous injection of cisplatin. Such DNA fragmentation was less conspicuous in rats given ginsenoside-Rd orally for 30 days prior to cisplatin administration. Significant suppression of the DNA fragmentation was also demonstrated by densitometry, and measurement of urea nitrogen and creatinine in blood also showed a marked decrease in their respective levels in rats administered ginsenoside-Rd. The present findings suggest that ginsenoside-Rd ameliorates cisplatin-induced renal injury, a process in which apoptosis plays a central role, and thereby causes restoration of the renal function.

Glutathione content is correlated with the sensitivity of lines of PC12 cells to cisplatin without a corresponding change in the accumulation of platinum

A study of the involvement of glutathione (GSH) in cellular resistance to cisplatin was performed using methylmercury-resistant sublines (PC12/TM series) of the PC12 line of rat pheochromocytoma cells. The seven clonal sublines of PC12 cells (PC12/TM, PC12/TM2, PC12/TM5, PC12/TM11, PC12/TM15, PC12/TM23, PC12/TM26) used in the study had intracellular levels of GSH that ranged from 8.7-39.9 nmol/mg protein. The intracellular level of GSH was significantly correlated (p < 0.01, r = 0.87) with the sensitivity to cisplatin of PC12 cells and the seven sublines. Among the seven sublines, PC12/TM cells contained the highest concentration of GSH and were the most resistant to cisplatin. Treatment of PC12/TM cells with L-buthionine-SR-sulfoximine, which reduced the level of GSH to that in the parental PC12 cells, significantly reduced the resistance of the cells to cisplatin. The amount of platinum accumulated by resistant PC12/TM cells after treatment with cisplatin was higher than that by sensitive PC12 cells. These results suggest that the intracellular level of GSH might be directly involved in the resistance to cisplatin of these cell lines. However, a high intracellular concentration of GSH does not appear to contribute to a decrease in the accumulation of cisplatin in these cells.

Targeting superoxide dismutase to renal proximal tubule cells inhibits nephrotoxicity of cisplatin and increases the survival of cancer-bearing mice

Because cis-diamminedichloroplatinum(II) (cisplatin) which generates reactive oxygen species induces renal dysfunction, administration of a large dose for killing cancer cells is highly limited. We recently synthesized a cationic superoxide dismutase (SOD) (hexamethylenediamine-conjugated SOD, AH-SOD) which rapidly accumulates in renal proximal tubule cells and inhibits oxidative injury of the kidney. Treatment of Ehrlich ascites tumor cells (EATC)-bearing mice with cisplatin sufficient for killing tumor cells increased their motality. The motality of cisplatin-treated EATC-bearing mice was markedly decreased by AH-SOD. These results suggest that targeting SOD to renal proximal tubule cells might permit the administration of high doses of cisplatin and related anticancer agents without causing renal injury.

Salviae radix extract prevents cisplatin-induced acute renal failure in rabbits

The present study was carried out to determine if salviae radix extract (SRE) exerts a beneficial effect against cisplatin-induced renal failure in rabbits. Rabbits were pretreated with SRE orally for 7 days, followed by cisplatin injection (5 mg/kg i.p.). Cisplatin injection caused a reduction in GFR, which was accompanied by an increase in serum creatinine levels. The fractional Na+ excretion was increased by cisplatin injection. PAH uptake by renal cortical slices was inhibited by the administration of cisplatin. Such changes were prevented by SRE pretreatment. Cisplatin injection increased lipid peroxidation, which was prevented by SRE pretreatment. The protective effect of SRE was supported by morphological studies. Cisplatin injection reduced renal blood flow that was not affected by SRE pretreatment. Cisplatin treatment in vitro in renal cortical slices increased LDH release and lipid peroxidation, which were prevented by 0.05% SRE. These results indicate that lipid peroxidation plays a critical role in cisplatin-induced acute renal failure. SRE exerts a protective effect against renal cell injury induced by cisplatin, and its effect may be attributed to its antioxidant action. However, the underlying mechanism by which SRE has antioxidant action remains to be defined.

L-n-acetyl-cysteine protection against cisplatin-induced auditory neuronal and hair cell toxicity

OBJECTIVES

The aim of this study is to determine the efficacy of L-N-acetyl-cysteine (L-NAC) as a protectant for inner ear auditory sensory cells against the toxic effects of cisplatin.

STUDY DESIGN

Prospective laboratory study of the otoprotective effect of L-NAC on auditory neurons and hair cells in vitro.

METHODS

The study has two arms. The first arm evaluated the neuroprotective effect of L-NAC on early postpartum auditory ganglion cell cultures. Two culture media were used. The two media differed in that one of them was enhanced by the addition of neurotrophins (neurotrophin type 3 and brain-derived neurotrophic factor) and a growth factor (transforming growth factor-beta1). Then the survival of cisplatin-treated auditory neurons was studied before and after pretreatment with protective levels of L-NAC. The second arm of the study evaluated the effect of L-NAC on cisplatin damage initiated to auditory hair cells. Early-postpartum organ of Corti explants were grown in culture. Their rate of survival was studied after exposure to toxic levels of cisplatin. Then, survival of cisplatin-damaged hair cells was studied after they were pretreated with L-NAC.

RESULTS

Pretreatment of cultures with L-NAC protected both auditory neurons and hair cells from the effects of exposure to toxic levels of cisplatin. This observed otoprotective effect was dose dependent.

CONCLUSIONS

Our in vitro studies have demonstrated that L-NAC protected both auditory neurons and hair cells from the toxic effects of cisplatin. Because it protects both of these inner ear structures, L-NAC may be potentially useful in protecting hearing, in general, from cisplatin-induced damage. In addition, L-NAC has low systemic and mucosal toxicity. It also has a low molecular weight that may allow it to readily cross the round window membrane. All these characteristics make it potentially suitable for transtympanic application for the prevention of the ototoxicity of cisplatin in vivo.

Antioxidant action of bixin against cisplatin-induced chromosome aberrations and lipid peroxidation in rats

Cisplatin is one of the most active cytotoxic agents in the treatment of cancer, but has serious side effects, inducing nephrotoxicity and chromosome aberrations. In this study we evaluated the role of the carotenoid bixin on cisplatin-induced oxidative stress in Wistar rats through three markers of oxidative damage: chromosome aberrations, glutathione depletion and lipid peroxidation. The animals were divided into six treatment groups with six rats in each (n= 6). The dose of cisplatin (5.0 mg kg(-1)body wt.) was injected i.p. and bixin (2.5 or 5.0 mg kg(-1)body wt.) was given by gavage at 48, 24 h and 10 min before the cisplatin injection. The treatment with the highest dose of bixin resulted in a statistically significant reduction, by about 33%, in cisplatin-induced abnormal metaphases (P< 0.05). A single dose of cisplatin enhanced the formation of lipid peroxides in 29% and resulted in a 29% depletion in renal glutathione 24 h after cisplatin administration (P< 0.05). The pretreatment with bixin reduced the total number of chromosome aberrations, inhibited the increase in lipid peroxidation, and inhibited renal glutathione depletion induced by cisplatin. Since the pretreatment with bixin alone was safe, under the present experimental conditions, the results suggest that bixin may have future clinical application after further studies.

Differential vulnerability of basal and apical hair cells is based on intrinsic susceptibility to free radicals

The base of the cochlea is more vulnerable to trauma than the apex as seen in the pattern of hair cell damage by cisplatin or aminoglycosides. The differential vulnerability is maintained in organotypic cultures exposed directly to these drugs, suggesting there may be an intrinsic difference in sensitivity to damage along the cochlear spiral. We therefore investigated the survival capacity of isolated outer hair cells and strips dissected from different turns of the guinea pig organ of Corti in short-term culture. Cells were stained with fluorescent indicators of viable or dead cells, calcein-AM and ethidium homodimer. After 5 h at room temperature, up to 90% of outer hair cells from the apex survived, but less than 30% from the base. In contrast, basal inner hair cells remained viable, and supporting cells survived for at least 20 h. The difference in survival capacity between basal and apical outer hair cells coincided with a significantly lower level of the antioxidant glutathione in basal outer hair cells compared with apical outer hair cells. This suggested that basal outer hair cells may be more vulnerable to free-radical damage than apical outer hair cells. The survival of basal outer hair cells was significantly improved by addition of the radical scavengers n-acetyl cysteine, p-phenylenediamine, glutathione, mannitol or salicylate. The protection by antioxidants implies that the accelerated death of basal outer hair cells is due to free-radical damage. The results support an intrinsic susceptibility to free radicals that differs among cochlear cell populations. This differential provides a rational explanation for base-to-apex gradients observed in various forms of cochlear pathology.

Targeting Superoxide Dismutase to Renal Proximal Tubule Cells Inhibits Mitochondrial Injury and Renal Dysfunction Induced by Cisplatin

We recently reported the synthesis of a cationic superoxide dismutase (SOD) derivative (AH-SOD) that rapidly and selectively accumulates in and around proximal tubule cells and effectively dismutes superoxide radicals in situ. The present study revealed that administration of cis-diamminedichloroplatinum(II)-elicited oxidative stress in renal mitochondria, decreased the renal expression of Bcl-x, released cytochrome c from mitochondria to cytosol, and induced apoptosis and renal dysfunction by a mechanism that was inhibited by AH-SOD. These results suggest that targeting SOD to proximal tubule cells protects renal function and permits the administration of fairly high doses of nephrotoxic anticancer agents, such as cisplatin, without causing renal injury.

Effects of the antioxidants curcumin or selenium on cisplatin-induced nephrotoxicity and lipid peroxidation in rats

A large number of natural products and dietary components have been evaluated as potential chemoprotective agents. In the present investigation we report the effects of pre-treatment with two dietary antioxidants, curcumin (8 mg kg-1 body wt.) or selenium (1 mg kg-1 body wt.), on cisplatin-induced lipid peroxidation and nephrotoxicity in Wistar rats. Adult male rats were divided into six treatment and control groups of six rats each. The animals were pre-treated by gavage with two doses of each antioxidant, one dose 24 h and the second 10 min before cisplatin intraperitoneal injection (5 mg kg-1 body wt.). The rats were killed 3 days after cisplatin injection and serum, urine and kidney were isolated and analysed. Cisplatin administration resulted in significant reduction of body weight and higher urinary volumes were observed in all groups treated with this antitumor drug (P< 0.05). The animals treated with cisplatin showed a depletion of renal glutathione, increased lipid peroxidation, and an increase in serum creatinine levels (P< 0.05). The administration of curcumin or selenium alone did not increase lipid peroxidation compared to the control group (P> 0.05). Three days after curcumin or selenium plus cisplatin treatments, the renal damage induced by cisplatin did not recover at a significant statistically level. This study suggests that the natural antioxidants curcumin or selenium did not offer protection against cisplatin-induced nephrotoxicity and lipid peroxidation in adult Wistar rats.

Renal toxicity caused by cisplatinum in glutathione-depleted metallothionein-null mice

To elucidate the protective role of metallothionein (MT) and glutathione (GSH) in renal toxicity caused by cisplatinum (cis-DDP), we examined the sensitivity of GSH-depleted MT-null mice to the renal toxicity of cis-DDP. Blood urea nitrogen and creatinine values in the serum, and histopathological change in the kidney were utilized as indicators of nephrotoxicity caused by cis-DDP. Although cis-DDP exerted renal toxicity in MT-null mice and wild-type mice, the toxicity was more conspicuous in the MT-null mice than in the wild-type mice. Moreover, renal toxicity caused by cis-DDP was enhanced significantly by a decrease in the renal GSH level by buthionine sulfoximine (BSO) pretreatment in both kinds of mice. The cis-DDP-caused nephrotoxicity that was enhanced by BSO-mediated GSH depletion was much more severe in the MT-null mice than in the wild-type mice. However, preadministration of zinc sulfate cancelled the BSO-enhanced, cis-DDP-dependent renal toxicity in the wild-type mice, but not in the MT-null mice. In the present study, we found that MT and GSH play an important, cooperative role in detoxification of severe kidney damage caused by cis-DDP. Moreover, the renal MT preinduced by zinc could protect mice from cis-DDP nephrotoxicity enhanced by GSH depletion.

The protective effect of melatonin on cisplatin nephrotoxicity

Regarding the mechanisms of cisplatin (CP) nephrotoxicity, several hypotheses have been put forward, among which oxidative stress (including depletion of glutathione and production of lipid peroxide) is noticeable. This investigation elucidates the role of the antioxidant system in CP-induced nephrotoxicity and the nephroprotection by melatonin. Balb/c mice were injected i.p. with: 1) vehicle control; 2) a single dose of 6.5 mg/kg cisplatin, CP group; 3) melatonin in a dose of 10 mg/kg for 5 days after CP injection, CP-M group; 4) melatonin (10 mg/kg) for 5 days before and after CP injection, M-CP-M group; 5) melatonin in a dose of 10 mg/kg for 5 days, M group. Mice were sacrificed 5 days after CP injection to determine blood urea nitrogen (BUN) and serum creatinine. Renal lipid peroxidation (LP) and glutathione (GSH) levels were evaluated in kidney homogenates. Cisplatin administration resulted in increased LP, BUN and serum creatinine levels and decreased GSH levels, whereas melatonin reversed these effects. Morphological kidney damage was apparent in the CP group. Mentioned degeneration was moderate in the CP-M group, whereas morphological findings of the M-CP-M group implied a well preserved kidney tissue. When M was administered alone, it didn't cause any significant change in biochemical parameters. Both C and M groups exhibited similar biochemical and morphological findings in light and transmission electron microscope observation. In conclusion, the present study suggests that melatonin may be of therapeutic benefit when used with CP.

The effect of thymol and its derivatives on reactions generating reactive oxygen species

The effects of thymol (TOH), thymoquinone (TQ) and dithymoquinone (TQ2) on the reactions generating reactive oxygen species (ROS) such as superoxide anion radical (O2*-), hydroxyl radical (HO*) and singlet oxygen (1O2) were tested using the chemiluminescence (CL) and spectrophotometry methods. All tested compounds acted as scavengers of various ROS. The rate constant of 1O2-dimols quenching by thymol was calculated.

Nitric oxide synthase inhibitor reduces the apoptotic change in the cisplatin-treated cochlea of guinea pigs

Cisplatin is known to cause inner ear damage. The role of nitric oxide (NO) in the cochlea of the guinea pigs after injections of cisplatin or a combination of cisplatin and NO synthase (NOS) inhibitor [N(G)-nitro-L-arginine methyl ester (L-NAME)] i.p. was examined by means of immunohistochemistry. Three days after injection, the cochleas were examined immunohistochemically for single-stranded DNA (ssDNA). We found that ssDNA was expressed in the stria vascularis and spiral ganglion cells of the cisplatin-treated cochlea. In the L-NAME/cisplatin-treated cochlea, the number of cells that exhibited positive staining for ssDNA was markedly reduced. High NO levels lead to inner ear dysfunction under pathological conditions. Our results indicate that NO mediates the ototoxicity of cisplatin.

Prevention of nephrotoxicity of cisplatin by repeated oral administration of ebselen in rats

The ability of ebselen, which exhibits glutathione peroxidase (GSH-Px)-like activity, to prevent cisplatin (CDDP)-induced nephrotoxicity was examined in rats. CDDP (6 mg/kg [20 micromol/kg] body weight) was injected intraperitoneally. In subgroups, daily ebselen doses of 2.75 (10 micromol), 5.5 (20 micromol), or 11.0 mg (40 micromol)/kg body weight were administrated orally 1 hour prior to CDDP treatment. Treatment with CDDP alone resulted in significantly increased plasma creatinine (Cr) and blood urea nitrogen (BUN) levels. Repeated administration of 5.5 and 11.0 mg/kg ebselen prevented the CDDP-induced elevation of plasma Cr and BUN levels and protected against kidney damage. Relative to controls, rat that received CDDP treatment displayed a decreased ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG), an indicator directly related to oxidative stress, and elevated malondialdehyde (MDA) levels in the kidney. In comparison with controls, activity of GSH-Px activity, which antioxidant enzyme, was also reduced in the kidney of rats treated with CDDP. Repeated administration of 5.5 or 11.0 mg/kg ebselen prevented CDDP-induced alteration of GSH/GSSG ratios, MDA levels, and GSH-Px activity; however, no protection against CDDP was observed with administration of 2.75 mg/kg ebselen. Effective protection of CDDP-induced nephrotoxicity with ebselen was observed only when the molar amount of each daily ebselen treatment equaled or exceeded

A randomized trial comparing the nephrotoxicity of cisplatin/ifosfamide-based combination chemotherapy with or without amifostine in patients with solid tumors

This study evaluates the degree of kidney damage during cisplatin/ifosfamide-based combination chemotherapy and its possible prevention by amifostine. Thirty-one patients with solid tumors stratified according to pretreatment were randomized to receive VIP- or TIP-chemotherapy with or without amifostine (910 mg/m2) given as a short infusion prior to cisplatin. Chemotherapy consisted of cisplatin (50 mg/m2), ifosfamide (4 g/m2) and either etoposide (500 mg/m2) (= VIP) or paclitaxel (175 mg/m2) (= TIP) repeated at 3 weekly intervals. For all patients the glomerular filtration rate (GFR) measured by creatinine-clearance, serum creatinine, electrolytes and differential urinary protein/enzyme excretion were determined prior to, during and after each cycle. A total of 62 cycles of chemotherapy were evaluable. In the amifostine-group GFR was fully maintained after application of two cycles of chemotherapy, whereas in the control group a > 30%-reduction of median GFR (108 to 80 ml/min) was observed (p < 0.001). Patients receiving amifostine had a lower degree of high molecular weight proteins excretion indicating less glomerular damage. In both groups significant increases of tubular marker profiles peaking at day 3 after chemotherapy were observed with a nearly complete reversibility of these changes prior to the next chemotherapy cycle. The number of patients with low magnesium serum levels during treatment was 17% after amifostine application versus 69% in control patients. The results seem to indicate that treatment with amifostine can preserve GFR after application of two cisplatin/ifosfamide-based chemotherapy cycles. This may be advantageous if repetitive cycles of chemotherapy or subsequent administration of high dose chemotherapy is planned.

Nitric oxide synthase inhibitor suppresses the ototoxic side effect of cisplatin in guinea pigs

Cisplatin is known to cause inner ear damage (ototoxicity). The role of inducible nitric oxide synthase (iNOS) in the cochlea of guinea pigs after injections of cisplatin or a combination of cisplatin and NOS inhibitor (NG-nitro-L-arginine methyl ester, L-NAME) i.p. was examined electro-and immunohistochemically. The auditory brain stem responses (ABR) were measured prior to injection and 3 days after the injection. Three days after injection, the cochleas were examined immunohistochemically for iNOS. We found that iNOS was expressed in the cisplatin- and L-NAME/ cisplatin-treated cochlea. The threshold shift of ABR was significant in the cisplatin group, whereas it was decreased in the L-NAME/cisplatin group. iNOS catalyzed high NO levels lead to inner ear dysfunction. Our results indicate that iNOS mediates the ototoxicity of cisplatin.

Protective effects of vitamin c against cisplatin-induced nephrotoxicity and lipid peroxidation in adult rats: a dose-dependent study

Cisplatin is one of the most active cytotoxic agents in the treatment of cancer, but its clinical use is associated with nephrotoxicity. In the present study we report the effects of different amounts of vitamin C (50, 100 or 200 mg kg(-1)body wt.) in rat kidneys treated with cisplatin (5 mg kg(-1)body wt.), using single doses of both compounds. Cisplatin administration induced lipid peroxidation which was accompanied by a decrease in renal glutathione level in animals killed 7 days after treatments. Furthermore, an increase in serum creatinine has been observed. Treatment of animals with vitamin C 10 min prior to the cisplatin inhibited cisplatin-mediated damage. Seven days after vitamin C plus cisplatin treatments, the depleted level of glutathione and changes in the creatinine clearance recovered to significant levels (P<0.05). Similarly, the enhanced serum creatinine levels which are indicative of renal injury showed a significant reduction (P<0.05) with the three doses of vitamin C tested. The protective effect of vitamin C was dose-dependent. The results suggest that vitamin C is an effective chemoprotective agent against nephrotoxicity induced by the antitumoral cisplatin in Wistar adult rats.

The role of ginsenoside-Rd in cisplatin-induced acute renal failure

Ginsenoside-Rd has been proved to decrease the severity of renal injury induced by cisplatin, in which proximal urinaferous tubules represent the main site of injury. When ginsenoside-Rd was given orally at a dose of 1 or 5 mg/kg body weight/day for 30 consecutive days prior to cisplatin injection, the activities of the antioxidation enzymes superoxide dismutase and catalase were higher, while malondialdehyde levels in serum and renal tissue were lower in the treated rats than in the controls. The levels of urea nitrogen and creatinine in serum were decreased in rats given ginsenoside-Rd. Decreased urinary levels of glucose, sodium and potassium reflected a protective action against the renal dysfunction caused by cisplatin. In addition, it was demonstrated that ginsenoside-Rd affected cultured proximal tubule cells exposed to cisplatin.

Expression of heat shock protein 72 in rat cochlea with cisplatin-induced acute ototoxicity

Cisplatin ototoxicity is known to involve mainly the organ of Corti. Outer hair cells (OHCs). especially in the basal turn, are preferentially involved. One possible mechanism of ototoxicity might be alteration of the antioxidant system causing an increase in free radicals. It has been demonstrated that heat shock proteins (HSPs), which are believed to protect cells by dissolving and refolding misfolded or denatured protein are induced by various form of stress. HSP is also demonstrated to be induced by free radicals. The purpose of this study was to evaluate HSP 72 induction in cochlea following cisplatin injection in the animal model. Sprague-Dawley (SD) rats were injected intraperitoneally with normal saline as control or cisplatin at a dose of 5, 10 or 20 mg/kg. Cochleae were harvested 1, 3, 6 and 12 h after injection and compared with those of controls. Immunocytochemical study with surface preparation and Western blotting were performed to investigate the expression of HSP 72. Auditory brainstem response (ABR) was also recorded to assess functional change according to the dosage of cisplatin and duration after injection. In the 5 and 10 mg/kg groups, immunostaining for HSP 72 in the OHCs reached a plateau level at 3 h, which was maintained until 12 h after injection. The amount of immunoreactive OHCs in the 20 mg/kg group was smaller than those in 5 and 10 mg/kg groups and declined after 6 h. The bands for HSP 72 became less intense as the cisplatin dosage increased from 5 to 10 and 20 mg/kg in Western blotting. The change in ABR threshold was small in the 5 and 10 mg/kg groups and a marked change in threshold was observed in the 20 mg/kg group. Detection of HSP 72 after cisplatin injection could confirm the OHCs as one of the major injured cells in the cochlea. With a lethal dosage of cisplatin (20 mg/kg), HSP 72 expression was less prominent and declined after 6 h.

PREVENTION OF CISPLATIN-INDUCED NEPHROTOXICITY BY METHIMAZOLE

Nephrotoxicity is a dose-limiting factor in the use of cisplatin against solid tumours. Methimazole, an antithyroid drug containing a free SH group, has a nephroprotective potential against chemically-induced nephrotoxicity. We tried to explore the nephrotoxic effect of the experimentally therapeutic dose of cisplatin (7 mg kg(-1), i.p.), particularly on the nuclear level of kidney cells in male albino rats, as well as the possible protective effect of methimazole. Furthermore, the drug interaction regarding the oncolytic effect of cisplatin was examined in Ehrlich ascites carcinoma (EAC)-bearing mice. A single dose of cisplatin caused kidney damage, 6 days after injection, manifested by 219% increase in serum creatinine, 384% increase in blood urea nitrogen and 170% increase in kidney content of lipid peroxides. Kidney DNA showed clear fragmentations detected by gel electrophoresis. However, kidney reduced glutathione was unchanged at that time period. Histological examination of kidney confirmed the toxic effect of cisplatin. Methimazole (40 mg kg(-1), i.p., 30 min before cisplatin injection) significantly protected the kidney from the nephrotoxic effect of cisplatin as judged from the biochemical parameters investigated as well as the histopathological examination. On the other hand, the survival data in EAC-bearing mice treated with both drugs indicated the persistence of an effective cytotoxic action. This study points to a promising use of this combination and necessitates further experimental and clinical studies. 2000 Academic Press@p$hr Copyright 2000 Academic Press.

Protection and spontaneous recovery from cisplatin-induced hearing loss

Cisplatin [cis-diamminechloroplatinum(II)] has proved itself as a potent antineoplastic agent. However, nephrotoxicity, neurotoxicity, gastrointestinal toxicity, myelosuppression, and ototoxicity interfere with its therapeutical efficacy. Forced diuresis reduces nephrotoxicity, effectively leaving neurotoxicity and ototoxicity as the major side effects of concern, and gastrointestinal toxicity and myelosuppression as the secondary side effects. So far, attempts to reduce these side effects by developing equally potent platinum analogs have been unsuccessful. Some success has been achieved, however, by co-treatment with protective agents. Nearly all these agents are sulfur- or sulfhydryl-containing compounds (thio compounds), known as antioxidants and potent heavy metal chelators. These thio compounds may provide protection from cisplatin toxicity either (1) by direct interaction between the cisplatin and the thio moiety, (2) by displacing platinum from its site of toxic action, (3) by preventing platinum from interfering with superoxide dismutase, or (4) by scavenging of cisplatin-induced free radicals. In particular the first two protective mechanisms bear the risk of reducing the antineoplastic activity of cisplatin. Since nephrotoxicity can be controlled effectively by forced diuresis, a more specific approach of coping with ototoxicity by focusing on protection at the sensorineural level was chosen. Being familiar with the neuro-protective and neurotrophic properties of ACTH-related neuropeptides, specifically against cisplatin-induced peripheral neuropathies, it was judged expedient to test for a possible otoprotective action of these neuropeptides. The results were positive, although tainted with high interanimal variability. When testing for the possibility that the neuropeptides would merely delay cisplatin-induced ototoxicity rather than reduce it, it was discovered in control series without neuropeptide co-treatment that the ear can recover spontaneously from cisplatin-induced hearing loss. This was found both electrophysiologically and in outer hair cell (OHC) counts. Although these preliminary findings require further investigation, they strongly suggest that spontaneous recovery of cochlear injury can occur in the mature mammalian cochlea. Moreover, the otoprotective action of the ACTH-related neuropeptides suggests that it may be possible to stimulate recovery from acute hearing loss using neuropeptides.

Oxidant mechanisms in toxic acute renal failure

Over the last decade, there is accumulating evidence for a role of reactive oxygen metabolites in the pathogenesis of a variety of renal diseases, including gentamicin, glycerol, cisplatin, and cyclosporine A models of toxic acute renal failure. Gentamicin has been shown both in in vitro and in vivo studies to enhance the generation of reactive oxygen metabolites. Iron is important in models of tissue injury, presumably because it is capable of catalyzing free-radical formation. Gentamicin has been shown to cause release of iron from renal cortical mitochondria. Scavengers of reactive oxygen metabolites as well as iron chelators provide protection in gentamicin-induced nephrotoxicity. In glycerol-induced acute renal failure, an animal model of rhabdomyolysis, there is enhanced generation of hydrogen peroxide, and scavengers of reactive oxygen metabolites and iron chelators provide protection. Although the dogma is that the myoglobin is the source of iron, recent studies suggest that cytochrome P450 may be an important source of iron in this model. In addition, there are marked alterations in antioxidant defenses, such as glutathione, as well as changes in heme oxygenase. Several recent in vitro and in vivo studies indicate an important role of reactive oxygen metabolites in cisplatin-induced nephrotoxicity. Thus, catalytic iron is increased both in vitro and in vivo by cisplatin, and iron chelators as well as hydroxyl radical scavengers have been shown to be protective. Recent studies indicate that cytochrome P450 may also be an important source of the catalytic iron in cisplatin nephrotoxicity. Cyclosporine A has been shown to enhance generation of hydrogen peroxide in vitro and enhance lipid peroxidation in vitro and in vivo. Antioxidants have been shown to be protective in cyclosporine A nephrotoxicity. This collective body of evidence suggests an important role for reactive oxygen metabolites in toxic acute renal failure and may provide therapeutic opportunities of preventing or treating acute renal failure in humans.

Protection against cis-diamminedichloroplatinum-induced nephrotoxicity by 2,3-dimercaptosuccinic acid in rats

The present study was designed to examine the usefulness of 2,3-dimercaptosuccinic acid (DMSA) for the purpose of reducing cis-diamminedichloroplatinum (DDP)-induced nephrotoxicity and effective clinical use of DDP and safe. The effectiveness of DMSA on the DDP-excretion in rat kidney was observed by measuring the platinum concentration using Atomic Absorption Instrument. Co-administration of DMSA (1.0 or 2.0 mmol/kg) 1 hour after DDP injection (20 mumol/kg) showed more decrease in the platinum concentration than that immediately after DDP injection. The alleviating effect of DMSA on DDP toxicity was evaluated by lipid peroxidation, enzymatic antioxidants, and glutathione levels. The administration of DDP alone caused a significant increase in lipid peroxidation and significant decreases in enzymatic antioxidants and glutathione levels in the kidney. Co-administration of DMSA (2.0 mmol/kg) 1 hour after DDP injection showed the most effective reduction of these enzymatic damages caused by DDP. These findings suggested that the co-administration of DMSA (2.0 mmol/kg) 1 hour after DDP injection leads DDP to effective excrete from renal tissue and suppresses the lipid peroxide reaction and results in reduction of nephrotoxicity.

Effects of green tea tannin on cisplatin-induced nephropathy in LLC-PK1 cells and rats

A study was conducted to clarify whether green tea tannin ameliorated cisplatin-induced renal injury in terms of lactate dehydrogenase and malondialdehyde leakage from a renal epithelial cell line, swine-derived LLC-PK1 cells in culture. Green tea tannin was shown to suppress the cytotoxicity of cisplatin, the suppressive effect increasing with the dose of green tea tannin. The effect of cisplatin was then investigated in rats given green tea tannin for 40 days before cisplatin administration and in control rats given no green tea tannin. In control rats, blood, urinary and renal parameters and the activities of antioxidative enzymes in renal tissue deviated from the normal range, indicating dysfunction of the kidneys. In contrast, rats given green tea tannin showed decreased blood levels of urea nitrogen and creatinine, and decreased urinary levels of protein and glucose, reflecting less damage to the kidney. In this group, the activity of catalase in the renal tissue was increased, while the level of malondialdehyde was decreased, suggesting the involvement of radicals in the normalizing of kidney function. Based on the evidence available it appeared that green tea tannin eliminated oxidative stress and was beneficial to renal function.

Possible involvement of thioredoxin reductase as well as thioredoxin in cellular sensitivity to cis-diamminedichloroplatinum (II)

The thioredoxin (TRX) system, composed of nicotinamide adenine dinucleotide phosphate (reduced form), TRX, and TRX reductase (TRXR), has multiple biologic functions via thiol-mediated redox control. In this study, we investigated the relationship between intracellular TRXR levels and cellular sensitivity to cis-diamminedichloroplatinum (II) (CDDP). HeLa, a human cervical carcinoma cell line, cultured with CDDP showed a time- and dose-dependent reduction of intracellular TRXR activity, which was well correlated with the decrease in cell viability after exposure to CDDP. In a cell-free system, CDDP was found to directly inactivate the reduced form of purified human TRXR. The CDDP-resistant variants of HeLa cells, established by continuous exposure to CDDP, exhibited an increased expression and activity of TRXR as well as TRX compared with the parental cells. In addition, sodium selenate, an inhibitor of TRXR, was found to increase the susceptibility to CDDP in the CDDP-resistant cells. Moreover, the HeLa cells transfected with an antisense TRXR RNA expression vector to reduce the intracellular enzyme activity displayed an enhanced sensitivity to CDDP. Taken together with previous reports on TRX, these results indicate the possible involvement of TRXR as well as TRX in the cellular sensitivity and resistance to CDDP.

Reduced sensitivity of HeLa cells to cis-platinum by simultaneous overexpression of copper, zinc-superoxide dismutase and catalase

The overexpression of catalase or Cu,Zn-superoxide dismutase (Cu,Zn-SOD) did not affect the sensitivity of HeLa cells to cis-platinum. However, the cytotoxicity of cis-platinum was depressed significantly by the simultaneous overexpression of catalase and Cu,Zn-SOD. We concluded that cis-platinum accelerated the generation of superoxide anion in the cells, and the superoxide anion produced was converted into H2O by the cooperative roles of catalase and Cu,Zn-SOD.