Cisplatin-induced changes in adenine nucleotides in rat kidney slices: amelioration by tiopronin and procaine

The protective role of tiopronin in cisplatin ototoxicity in Wistar rats

The purpose of this study was to evaluate cisplatin-induced ototoxicity and the protective effects of tiopronin. Twenty-four adult Wistar rats served as subjects and were divided into three groups. Eight rats receiving only saline (group A) were used as controls. Eight rats received cisplatin (2 mg/kg) injections (group B) and eight rats received cisplatin and tiopronin (300 mg/kg) (group C) for 8 consecutive days. Both ears of all animals were tested by DPOAE before treatment and on the 4th and 9th days. Seventy-two hours after the final recording session, all animals were killed, and the left cochleas were prepared for electron microscopy and analysed. DPOAE responses were significantly reduced in group B compared to controls (p<0.05). When tiopronin was added, DPOAE responses were significantly increased compared to those obtained with the administration of cisplatin alone (p<0.05). The cochleogram showed that tiopronin had a significant protective effect in the basal half and in the lower half of the middle turn. We conclude that tiopronin, a drug effective in protecting against cisplatin nephrotoxicity, is also effective in protecting against cisplatin ototoxicity.

Effects of adenine on the pituitary-gonad axis in newborns rats

The present study was undertaken to investigate effects of the adenine on the hypothalamus-pituitary-gonad axis and changes in blood hormone concentration such as FSH, LH, progesterone and estrogen in newborn female rats. Adenine is a common organic base and its concentration variations caused by foods, has various effects on the body metabolic systems. In present study, fifty newborns rats were used divided into five groups, of 10s, including control I, control II which received solvent (normal saline) only and three experimental groups which received 50, 100 and 200 mg body weight adenine respectively. All the animals were kept under same condition with plenty food and water and treated Intra Peritoneally (IP) during days 2-16 after birth. At the end of experiment, all the animals were weighed, their ovaries were removed and blood samples were taken for hormone analysis. The results showed that dose dependent adenine solution significantly reduced the body and ovarian weight on 30 and 70 days after birth. In addition adenine led into no significant difference in concentration of FSH and LH in the experimental groups relative to the control on 30th day of life. But on the 70th day, the levels of these hormones raised significantly in the experimental groups. Furthermore, the adenine solution significantly increased the levels of progesterone and estrogen hormones in the experimental groups relative to the control on the 30th day, while decreased their concentration significantly on the 70th day. This situation has close similarities to metabolic disorders present in human caused by excessive use of adenine. High amounts consumption of adenine in can lead into hormone abnormality, weight loss and metabolic anomalies.

Agents ameliorating or augmenting the nephrotoxicity of cisplatin and other platinum compounds: a review of some recent research

Cisplatin (cis-diamminedichloroplatinum (II)) is an effective agent against various solid tumours. Despite its effectiveness, the dose of cisplatin that can be administered is limited by its nephrotoxicity. Hundreds of platinum compounds (e.g. carboplatin, oxaliplatin, nedaplatin and the liposomal form lipoplatin) have been tested over the last two decades in order to improve the effectiveness and to lessen the toxicity of cisplatin. Several agents have been tested to see whether they could ameliorate or augment the nephrotoxicity of platinum drugs. This review summarizes these studies and the possible mechanisms of actions of these agents. The agents that have been shown to ameliorate experimental cisplatin nephrotoxicity include antioxidants (e.g. melatonin, vitamin E, selenium, and many others), modulators of nitric oxide (e.g. zinc histidine complex), agents interfering with metabolic pathways of cisplatin (e.g. procaine HCL), diuretics (e.g. furosemide and mannitol), and cytoprotective and antiapoptotic agents (e.g. amifostine and erythropoietin). Only few of these agents have been tested in humans. Those agents that have been shown to augment cisplatin nephrotoxicity include nitric oxide synthase inhibitors, spironolactone, gemcitabine and others. Combining these agents with cisplatin should be avoided.

Fructose-1,6 diphosphate as a protective agent for experimental ischemic acute renal failure

Cold ischemia time is a risk factor for the development of acute renal failure in the immediate post-transplant period. In this study, we aimed to determine if intravenous fructose-1,6-diphosphate (FDP), given before nephrectomy, attenuates renal cell injury in a cold ischemia model. Male adult Wistar rats were subjected to infusion of either FDP 350 mg/kg (group F, n=6), an equal volume of 0.9% NaCl (group S, n=6), an equal volume/osmolality of mannitol (group M, n=6) or no infusion (group C, n=7). Kidneys were then perfused in situ with Collins solution and nephrectomy was performed. Other kidney slices were stored in Collins solution at 4 degrees C. Adenosine triphosphate (ATP) levels and lactate dehydrogenase (LDH) release were examined at 0, 24, 48 and 72 h. Other slices, obtained after 50 min immersion in Collins solution at 37 degrees C, were frozen for characterization of cytoskeletal preservation using phalloidin-FITC staining. Apical fluorescence intensity of proximal tubule cells, indicative of the F-actin concentration, was measured in a fluorescence microscope interfaced with computer image analysis system. Adenosine triphosphate levels, after up to 72 h of tissue incubation, were higher (P<0.05) in the FDP group when compared to other groups. In addition, LDH release was smaller (P<0.0001) in the FDP group. The F-actin concentration of proximal tubule cells cells was greater in the FDP group (P<0.0001). Results indicate that FDP is a useful tool to increase tissue viability in a rat kidney subjected to cold ischemia, by maintaining ATP cell content, decreasing LDH release and preventing microfilament disruption of proximal tubule cells.

Cytochrome P450 2E1 null mice provide novel protection against cisplatin-induced nephrotoxicity and apoptosis

BACKGROUND

Reactive oxygen metabolites (ROM) are important mediators of cisplatin-induced nephrotoxicity and apoptosis. The site and source of generation of these metabolites are not well defined. Cytochrome P450 (CYP) are heme-containing enzymes that can generate ROM during the oxidative metabolism of exogenous and endogenous compounds. CYP2E1 was identified and localized to the kidney proximal tubule. There is evidence to suggest that CYP2E1 is involved in the generation of ROM.

METHODS

The current study was performed utilizing CYP2e1 null mice (CYP2e1-/-). Cisplatin nephrotoxicity was induced in mice by single intraperitoneal injection of cisplatin and animals were sacrificed 72 hours later. Renal function was assessed and various biochemical tests were performed, including histologic studies.

RESULTS

CYP2e1-/- demonstrated marked functional and histologic protection against cisplatin-induced renal injury. Incubation of CYP2e1-/- kidney slices with cisplatin resulted in significant decrease in the generation of ROM and attenuation of cytotoxicity as compared to that of wild-type mice (CYP2e1+/+). Cisplatin-induced apoptosis was also markedly reduced in the CYP2e1-/- mice. Direct incubation of cisplatin with the microsomes isolated from CYP2e1-/- kidney cortex produced significant decrease in the generation of hydrogen peroxide, catalytic iron content, and hydroxyl radical formation compared to CYP2e1+/+ microsomes.

CONCLUSION

Our results thus demonstrate a pivotal role of CYP2E1 in cisplatin-induced nephrotoxicity and apoptosis. We postulate that the interaction of cisplatin with CYP2E1 results in the generation of ROM that causes renal injury and initiates apoptosis.

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.